代码拉取完成,页面将自动刷新
<!DOCTYPE html>
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="content-type">
<title>ch07-02</title>
<link href="css/style.css" rel="stylesheet" type="text/css">
<link rel="stylesheet" href="thumbnailviewer.css" type="text/css">
<script src="thumbnailviewer.js" type="text/javascript">
/***********************************************
* Image Thumbnail Viewer Script- © Dynamic Drive (www.dynamicdrive.com)
* This notice must stay intact for legal use.
* Visit http://www.dynamicdrive.com/ for full source code
***********************************************/
</script> </head>
<body>
<div class="os1">7.2 基本文件读写QFile</div>
<br>
Qt 常见的文件读写类有三个 QFile、QTextStream 和 QDataStream,本节先概要介绍这三个文件读写类,然后详细介绍 QFile
类的内容,从 QFile 的基类讲起,介绍 QFile 关于文件属性、权限方面的函数和实际中常用的读写函数,最后通过两个例子展示 QFile
类的用法,第一个例子是读写 Unix/Linux 常见配置文件,解析文本形式的配置项和数值;第二个例子是读取 BMP
图片文件头,解析字节数组(结构体)形式的文件。<br>
<br>
<div class="os2">7.2.1 三个常用文件读写类概览</div>
<br>
QFile、QTextStream 和 QDataStream 三个类的关系可以用下图来说明:<br>
<center><img src="images/ch07/ch07-02-01.png" alt="fileIO"></center>
QFile 是基本的文件读写类,它的主要功能其实就是负责打开文件,虽然它自己有读写文件中字节、字节数组的函数,但是直接用 QFile
类的接口函数读写文件的情况是相对少见的,因为 QFile 的读写函数功能比较简单,就是面向字节数据进行读写。<br>
C++ 和 Qt 常用的类型比如 int、double、QString、QRect等,都不是简单 char * 和 char 类型,如果用 QFile
读写这些常用数据类型,要手动转成 char * 来读写,比较麻烦。<br>
<br>
Qt 更为常用的文件读写类是 QTextStream 和 QDataStream ,这两个类都有类似的构造函数,构造函数是以 QFile *
指针为参数,它们为 C++ 和 Qt 常用的数据类型读写操作做了封装,类似标准 C++ 的 iostream 和 fstream。使用
QTextStream 和 QDataStream 之前,要先定义 QFile 对象,打开指定文件,然后根据 QFile 对象指针构造高级的读写类
QTextStream 和 QDataStream 对象,然后就可以用输入输出流的操作符 >> 和 << 读写变量。<br>
<br>
QTextStream 专门用于读写文本形式的文件,并且自动对文本字符的本地化编码做转换,在简体中文 Windows 系统它默认按照 GBK
的中文编码读写文本文件,在 Unix/Linux 系统自动以 UTF-8 编码读写文本文件,所以几乎不需要操心文本字符编码的问题。<br>
<br>
QDataStream 是 Qt
独有的“串行化数据流”,可以用于文件读写和网络数据流读写。对于文件或网络数据的读写,可以自己定义数据结构体封装不同基本类型的数据,然后作为一个整体数据块读写,但
这种方式不通用,因为数据类型一旦变化,就得重新定义结构体,读写代码也要大幅度变动,效率很低。串行化数据流,就是对所有已知数据类型全部做格式封装,相当于全
自动打包成结构体(不需要人为定义)收发,只要在发送(写入)和接收(读取)时按照相同顺序填充即可,其他的都交给 Qt
库处理,程序员就不用管数据是如何打包解包的,如果数据类型变了,只需要修改写入和读取的两句代码,其他的都不需要调整。<br>
<br>
本节先介绍 QFile 类的功能,后面两大节介绍 QTextStream 和 QDataStream ,下面先看 QFile 类的继承关系,因为
QFile 的读写函数其实都封装在基类 QIODevice 里面。<br>
<br>
<div class="os2">7.2.2 QFile 类继承关系</div>
<br>
在 Qt 帮助文档里面,如果直接查询 QFile 帮助文档,看不到几个关于文件读写的函数,因为 Qt 将读写操作都封装在基类 QIODevice 里面:<br>
<center><img src="images/ch07/ch07-02-02.png" alt="QFile"></center>
QIODevice 类是对输入输入设备的抽象建模,涉及到读写的文件类 QFile 、网络收发QTcpSocket/QUdpSocket、进程输入输出
QProcess,都是从 QIODevice 类派生的。QIODevice
是非常重要的基类,以后讲到网络收发和进程类时还会再讲,本节主要关注与文件读写相关的接口函数。<br>
QFileDevice 是对文件设备的抽象,其实在 Unix 和 Linux 系统中所有东西都是文件设备,就连硬件设备也抽象成文件设备,比如
/dev/usb0 是代表 USB 设备的文件,QFileDevice 就是描述文件设备的类,QFileDevice 这一层基类的接口函数比较少,可以不
用管的。<br>
QFile 类就是本节的学习重点,随后慢慢讲解。一同从 QFileDevice 派生的还有个 QSaveFile ,这个保存文件类,就为了安全地保存文件
而设计的,因为程序运行时可能有 bug
导致崩溃,如果崩溃时正在写入文件,那么文件被改写了一部分,但又没修改完全,会导致原始文件的损坏。QSaveFile
就是为了解决文件的不安全读写,避免出现半吊子问题,QSaveFile 有两个重要函数:cancelWriting() 函数取消写入操作,commit()
提交所有写入操作,知道 QSaveFile 有这两个函数就差不多了,因为也没其他重要功能。QSaveFile
类不单独讲了,因为就那两个重要函数而已。下面开始学习 QFile 类。<br>
<br>
<div class="os2">7.2.3 QFile功能函数</div>
<br>
在多数情况下,QFile 都是配合 QTextStream 和 QDataStream 使用,当然也可以使用 QFile
自带的读写函数处理文件。QFile 不仅适合于普通的文件系统,而且对 Qt 程序内嵌的资源文件也是通用的,区别只是内嵌资源文件全是只读的。下面大致分几块
来介绍 QFile 的功能函数:<br>
<br>
(1)构造函数和打开函数<br>
QFile 通常在构造函数里指定需要打开的文件名:<br>
<div class="code"> QFile(const QString & name)</div>
<div class="code"> QFile(QObject * parent)</div>
<div class="code"> QFile(const QString & name, QObject
* parent)</div>
参数 name 就是需要打开的文件名,注意必须是实际的文件路径,不能是只有文件夹路径。parent
是父对象指针。对于第二个构造函数,没有指定文件名,必须在之后的代码里用如下函数设置文件名:<br>
<div class="code">void QFile::setFileName(const QString & name)</div>
设置了文件名之后才能打开文件进行读写。获取文件名就用 fileName() 函数,不单独列了。<br>
<br>
可以使用多种模式打开文件,比如只读模式、只写模式、读写模式等,最常用的打开函数为:<br>
<div class="code">bool QFile::open(OpenMode mode)</div>
OpenMode 枚举类型是在基类 QIODevice 定义的,有如下打开模式:<br>
<br>
<table class="tabel">
<tbody>
<tr class="d1">
<td style="width: 200px;" align="center"><b>OpenMode 枚举常量</b></td>
<td style="width: 200px;" align="center"><b>数值</b></td>
<td align="center"><b> 描述</b></td>
</tr>
<tr>
<td>QIODevice::NotOpen</td>
<td> 0x0000 </td>
<td> 用于表示设备或文件尚未打开。 </td>
</tr>
<tr class="d1">
<td>QIODevice::ReadOnly</td>
<td> 0x0001 </td>
<td> 按读取模式打开。 </td>
</tr>
<tr>
<td>QIODevice::WriteOnly</td>
<td> 0x0002 </td>
<td> 按写入模式打开,注意单独用这个模式会暗含Truncate。 </td>
</tr>
<tr class="d1">
<td>QIODevice::ReadWrite</td>
<td> ReadOnly | WriteOnly </td>
<td> 按读取和写入模式打开,既能读也能写。 </td>
</tr>
<tr>
<td>QIODevice::Append</td>
<td> 0x0004 </td>
<td> 按追加模式打开,文件以前存在的内容不会被覆盖,新数据从文件末尾开始写入。 </td>
</tr>
<tr class="d1">
<td>QIODevice::Truncate</td>
<td> 0x0008 </td>
<td> 强制清空文件里以前存的旧数据,新数据从零开始写入。 </td>
</tr>
<tr>
<td>QIODevice::Text</td>
<td> 0x0010 </td>
<td> 在读取时,把行尾结束符修改为 '\n'; 在写入时,把行尾结束符修改为本地系统换行风格,比如Windows文本换行是 "\r\n"
</td>
</tr>
<tr class="d1">
<td>QIODevice::Unbuffered</td>
<td> 0x0020 </td>
<td> 忽略缓冲区,直接读写设备或文件。除非是实时性很强的程序,否则用不到。 </td>
</tr>
</tbody>
</table>
<br>
文件读取时,常见组合如下面两句:<br>
<div class="code">file.open(QIODevice::ReadOnly); //以只读方式打
开文件</div>
<div class="code">file.open(QIODevice::ReadOnly |
QIODevice::Text); //确定是读取文本文件,并且自动把换行符修改为 '\n'</div>
注意以 QIODevice::Text 模式打开文件时,读写的数据不一定是原始数据,因为 QFile
自动把换行符做了转换,读取得到的缓冲区数据与原始文件是可能不一样的,比如 Windows 文本,换行符是 "\r\n" 两个字符,用
QIODevice::Text 读取时只会看到 '\n' 一个字符;写入时就反过来,代码写入一个 '\n',实际文件就是两个连续字符
"\r\n",所以要注意 QIODevice::Text 模式读写的不一定是原始数据。<br>
<br>
对于文件写入时,其常用打开模式如下:<br>
<div class="code">file.open(QIODevice::WriteOnly);
//以只写模式打开,这个模式暗含 Truncate,会清空旧数据</div>
<div class="code">file.open(QIODevice::WriteOnly |
QIODevice::Truncate); //只写模式,清空旧数据</div>
<div class="code">file.open(QIODevice::WriteOnly | QIODevice::Append);
//只写和追加模式,不会清空旧数据</div>
<br>
如果文件打开时既要读,又要写,那么建议用如下模式:<br>
<div class="code">file.open(QIODevice::ReadWrite);
//读写模式,旧数据不会清空,可以读出来</div>
<br>
文件打开之后,可以用从 QIODevice 继承来的读写函数操作文件,或者用 QFile 对象指针构造 QTextStream 或
QDataStream 来读写文件。<br>
<br>
除了上面最常用的打开函数,另外还有两个不太常用的打开函数:<br>
<div class="code">bool QFile::open(FILE * fh, OpenMode mode,
FileHandleFlags handleFlags = DontCloseHandle)</div>
<div class="code">bool QFile::open(int fd, OpenMode mode, FileHandleFlags
handleFlags = DontCloseHandle)</div>
上面第一个不常用打开函数可以打开标准输入流 stdin、标准输出流 stdout、标准错误流 stderr
,或者其他文件句柄(Windows系统中参数里的 fh 句柄必须以二进制模式打开,打开句柄时要带 'b' 模式)。最后的参数 handleFlags
一般就用不关闭的 DontCloseHandle 就可以了,如果希望 QFile 对象析构时自动关闭文件或流,那么可以用
QFileDevice::AutoCloseHandle 。<br>
<br>
对于 Windows 平台,如果希望在图形界面程序里面用标准的输入输出和错误流,那么必须在项目文件加一句:<br>
<div class="code">CONFIG += console</div>
<br>
上面第二个不常用 open() 函数是以 fd 文件描述符参数,与 C 语言里面的文件读写用到的文件描述符类似,如果 fd 为 0 是标准输入流,为 1
是标准输出流,为 2 是标准错误流。<br>
<br>
<span style="font-weight: bold;">open() 函数打开正确就返回 true,否则返回
fasle,注意判断该函数的返回值,然后再进行文件读写操作!</span><br>
<br>
(2)读写函数<br>
本小节主要介绍从 QIODevice 继承而来的读写函数,这些函数要在 QIODevice 类帮助文档才能找到。<br>
首先是简单的字节读写函数:<br>
<div class="code">bool QIODevice::getChar(char * c)</div>
参数指针 c 就是读取的一个字节将要存到的变量指针,程序员需要自己先定义一个 char 变量,把这个变量地址传递给 getChar()
函数,如果读取一字节成功就返回 true;如果之前已经到了文件末尾,没有字节可以读了,就返回 false。 getChar() 函数有一个逆操作函数:<br>
<div class="code">void QIODevice::ungetChar(char c)</div>
这个函数就是把之前读取的字节 c (这次是变量,不是指针)放回去,并且当前读取游标减一,还原到读取之前状态。注意,如果 c
字节不等于之前读取的字节数值,那么 ungetChar() 函数操作结果无法预知,<span style="font-weight: bold;">所
以不要使用 ungetChar() 函数修改文件!</span><br>
<br>
写入一个字节到文件中,应该使用函数:<br>
<div class="code">bool QIODevice::putChar(char c)</div>
这个函数会把字节 c 写入文件,并将文件游标加一。<br>
<br>
这里我们专门讲一下文件游标,文件在读写时,共同使用一个唯一的游标(QFile内部有),我们这里随便取个名字叫 pos(Position),这个 pos
在文件刚打开时一般处于文件开头位置:<br>
<center><img src="images/ch07/ch07-02-03.png" alt="pos0"></center>
说明一下,文件的大小是用 size() 函数获取的:<br>
<div class="code">qint64 QFile::size() const</div>
文件大小使用 qint64 类型变量保存的,也就是说 QFile 最大支持 2^63 - 1 == 9,223,372,036,854,775,807
字节的文件,所以不用操心 QFile 对大文件的支持特性。<br>
<br>
QFile 当前游标可以用函数获取:<br>
<div class="code">qint64 QFileDevice::pos() const</div>
<br>
对于按字节读取的函数 getChar() ,每调用一次,文件游标就加 1,如果连续调用了 N 次,游标 pos 就会移动到下图所示位置:<br>
<center><img src="images/ch07/ch07-02-04.png" alt="posN"></center>
之前介绍的 getChar()、putChar() ,如果读写正确都会使 pos 自动加 1,ungetChar() 函数如果操作正确,那么会使
pos 自动减一,这个游标都是 QFile 自动控制,一般不需要手动移动游标。<br>
<br>
我们对文件读取到一定程度,就会读到文件末尾位置,到达末尾之后就无法再读数据了,因为游标已经超出范围:<br>
<center><img src="images/ch07/ch07-02-05.png" alt="posEnd"></center>
QFile 基类有快捷函数判断文件游标是否已到达文件末尾:
<div class="code">bool QFileDevice::atEnd() const</div>
<br>
对于字节读取函数,文件游标是按一字节移动的,如果要读取大段数据块,那么可以使用下面的函数:<br>
<div class="code">qint64 QIODevice::read(char * data, qint64 maxSize)</div>
data 通常是程序员手动分配的缓冲区,比如 char *buff = new char[256];<br>
maxSize 就是最多读取的字节数目,一般是手动分配的缓冲区大小,比如 256。<br>
该函数返回值一般就是正确读取的字节数目,因为如果文件后面如果没有 256 字节,那么有几个字节读几个字节。<br>
如果 read() 函数在读取之前就到了文件末尾或者读取错误,那么返回值是 -1 。对于使用 QIODevice::WriteOnly
只写模式打开的文件,通常文件游标总是指向文件末尾,这时候调用 read() 没意义,所以 read() 返回值就是 -1。<br>
<br>
手动分配缓冲区其实是比较麻烦的事情,我们 Qt 原生态的读取函数应该用下面这个:<br>
<div class="code">QByteArray QIODevice::read(qint64 maxSize)</div>
这里的 read() 函数会把读取的字节数组存到 QByteArray 对象并返回,参数里的 maxSize 就是最多读取的字节数目。返回的
QByteArray 对象里面,可以用 QByteArray 自己的 QByteArray::size()
函数判断读了多少字节,如果文件后面没字节可读或读取错误,那么 QByteArray 尺寸就是 0 。<br>
<div class="code">QByteArray QIODevice::readAll()</div>
readAll() 函数看名字就知道,把文件的全部内容直接读取到 QByteArray 对象然后返回。<br>
另外还有两个更实用的读取行的函数:<br>
<div class="code">qint64 QIODevice::readLine(char * data, qint64 maxSize)</div>
<div class="code">QByteArray QIODevice::readLine(qint64 maxSize = 0)</div>
第一个 readLine() 是程序员手动分配缓冲区,第二个不需要手动分配缓冲区。<br>
readLine() 函数工作特性比较特殊,它是从文件或设备里面读取一行 ASCII 字符,最多读取 maxSize-1
字节,因为最后一个字节预留给字符串结尾NULL字符 。<br>
该函数返回值是真实读取的字节数目,如果读取出错或无数据可读就返回 -1。<br>
readLine() 总会在实际读取的字符串末尾会自动添加一个字符串终结符 0 。<br>
<br>
readLine() 会一直读取数据直到如下三个条件之一满足:<br>
① 第一个 '\n' 字符读取到缓冲区。<br>
② maxSize - 1 字节数已读取,最后一个字节预留给 0 。<br>
③ 文件或设备读取已经到末尾。<br>
对于第一个终止条件,真实读取到了 '\n' 字符,那么这个换行字符会填充到缓冲区里面;<br>
对于第二个和第三个终止条件,是没有读到 '\n' 字符,那么该函数不会自动添加换行符到末尾。<br>
还有一个特殊情况要注意,readLine() 函数会把 Windows 的文件换行风格 "\r\n" 自动替换改为 '\n' 。<br>
<br>
read() 和 readAll() 、readLine() 函数都会移动文件游标,具体是看真实读了多少字节。<br>
<br>
以上主要是读操作,写操作除了 putChar() ,还有如下三个写函数:<br>
<div class="code">qint64 QIODevice::write(const char * data, qint64
maxSize)</div>
data 就是缓冲区数据指针,maxSize 是最多写入的字节数。 返回值是真实写入的字节数,因为可能出现磁盘不够的情况。 如果返回值是
-1,那么可能是写入出错或者无写入权限。这个写函数不区分 data 缓冲区里面的 '\0' 字符和普通字符串字符,都一股脑写进去。
<div class="code">qint64 QIODevice::write(const char * data)</div>
这第二个函数参数没指定缓冲区大小,会将参数里的 data 当作 '\0' 结尾的普通字符串,写入该字符串。这个函数等价于下面这句代码:
<div class="code">... <br>
QIODevice::write(data, qstrlen(data));<br>
...</div>
第三个写函数其实更常用:
<div class="code">qint64 QIODevice::write(const QByteArray & byteArray)</div>
byteArray 里面有多少字节就写入多少,这个也是不区分 '\0' 字符和普通字符串字符,都一股脑写进去。<br>
写操作函数也都会移动文件游标 pos,具体是看实际写入了多少字节。<br>
<br>
一般我们都不需要手动控制文件游标 pos,但是如果有特殊情况,需要手动移游标,那么通过下面函数:<br>
<div class="code">bool QFileDevice::seek(qint64 pos)</div>
seek 函数如果成功移动游标,那么会返回 true,否则返回 false。最好不要用 seek 函数移动游标到超出文件尺寸的位置,这样会导致无法预料
的结果。<br>
<br>
如果希望设置文件尺寸,提前在磁盘上分配空间,可以用如下函数:<br>
<div class="code">bool QFile::resize(qint64 sz)</div>
参数 sz 就是新的文件大小,如果新大小比旧的大,那么新增空间内容是随机的,需要程序员以后手动填充数据。重置大小成功就返回 true,否则返回
false。<br>
<br>
文件打开和读写操作结束之后,就可以关闭文件:<br>
<div class="code">void QFileDevice::close()</div>
在写操作过程中,如果需要立即把 Qt 内部写缓冲区的数据写入磁盘,可以调用:<br>
<div class="code">bool QFileDevice::flush() //这个函数很少用到,文件
关闭时自动会执行 flush</div>
<br>
(3)文件属性和权限等函数<br>
QFile 有部分函数其实与 QFileInfo 类功能差不多,这里大致讲解一下,对于这部分操作,其实更建议用 QFileInfo 或 QDir
类来实现。<br>
<div class="code">bool QFile::copy(const QString & newName)</div>
把当前文件复制到新文件 newName,复制成功就返回 true,否咋返回 false。<br>
注意如果 newName 新文件之前已经存在,那么 copy() 函数返回 false,它不会覆盖旧文件。<br>
当复制文件时,源文件自动会被关闭,以后使用源文件最好再重新打开。<br>
<div class="code">bool QFile::exists() const</div>
判断当前文件是否存在。<br>
<div class="code">bool QFile::link(const QString & linkName)</div>
为当前文件创建一个新的快捷方式 linkName ,创建成功返回 true,创建失败返回 false。link()
函数也不会覆盖之前已存在的快捷方式。对于 Windows 系统,快捷方式名必须以 .lnk 结尾,否则会出错。<br>
<div class="code">bool QFile::remove()</div>
删除当前文件,删除之前文件会自动被关闭,然后删除。<br>
<div class="code">bool QFile::rename(const QString & newName)</div>
把当前文件重命名为新名字 newName,如果成功返回 true,失败返回 false。如果 newName
文件之前已存在,那么重命名会失败,旧文件不会被覆盖。文件重命名之前,该文件也会自动关闭。<br>
<div class="code">QString QFile::symLinkTarget() const</div>
如果当前文件是快捷方式文件,那么 symLinkTarget() 返回原始文件的完整路径文件名,否则返回空字符串。<br>
<br>
<div class="code">Permissions QFile::permissions() const</div>
<div class="code">bool QFile::setPermissions(Permissions permissions)</div>
获取和设置文件权限的函数,Permissions 枚举变量与 7.1.3 QFileInfo 类的权限枚举是一样的。<br>
<br>
(4)QFile 类静态函数<br>
有好几个静态函数与上面(3)里的函数重名,只是参数通常比上面同名函数多一个,多的参数是源文件名,这里就不列举了。<br>
静态函数里面,有三个与上面内容不重复的:<br>
<div class="code">QString QFile::decodeName(const QByteArray &
localFileName)</div>
<div class="code">QString QFile::decodeName(const char * localFileName)</div>
这两个文件名解码函数把操作系统本地化的路径文件名转为 Qt 标准的 QString 路径文件名(路径分隔符是 '/')。<br>
当然也有文件名编码函数:<br>
<div class="code">QByteArray QFile::encodeName(const QString &
fileName)</div>
这个函数把 Qt 标准的 QString 文件名编码称为操作系统本地化的路径文件名。<br>
关于 QFile 类的功能函数介绍到这,下面来看看示例。<br>
<br>
<div class="os2">7.2.4 Unix风格配置文件读写示例</div>
<br>
Unix 风格配置文件大概如下面这样:<br>
<div class="code">#Address<br>
ip = 192.168.100.100<br>
port = 1234<br>
hostname = mypc<br>
workgroup = ustc</div>
以井号 '#'
打头的行都是注释,可以忽略掉。对于正常的配置行,等号左边的配置项名称,右边是配置项的数值。本示例中,我们要做的事就是读取有效的配置行,并且在图形界面可以修
改配置并保存为新的配置文件。<br>
上面配置文件是比较简单的,就四个配置项,我们用相应的控件实现配置项的显示和修改,并提供“保存”按钮,将修改后配置存到新文件。<br>
<br>
我们打开 QtCreator,新建一个 Qt Widgets Application 项目,在新建项目的向导里填写:<br>
①项目名称 unixconfig,创建路径 D:\QtProjects\ch07,点击下一步;<br>
②套件选择里面选择全部套件,点击下一步;<br>
③基类选择 QWidget,点击下一步;<br>
④项目管理不修改,点击完成。<br>
建好项目之后,先在项目文件夹里新建一个记事本文件,命名为 testconf.txt,把上面示范的五行文本保存到testconf.txt
里面,程序运行时会 用到。<br>
<br>
现在回到 QtCreator,打开窗体 widget.ui 文件,进入设计模式,按照下图排布,拖入控件:<br>
<center><img src="images/ch07/ch07-02-06.png" alt="ui" width="800"></center>
注意图上是七行控件:<br>
第一行是:标签控件,文本为 "源文件";单行编辑器,对象名 lineEditSrcFile;按钮控件,文本 "浏览源",对象名
pushButtonBrowseSrc;按钮控件,文本 "加载配置",对象名 pushButtonLoad。<br>
第二行是:标签控件,文本为 "目的文件";单行编辑器,对象名 lineEditDstFile;按钮控件,文本 "浏览目的",对象名
pushButtonBrowseDst;按钮控件,文本 "保存配置",对象名 pushButtonSave。<br>
第三行,是一个水平线条控件,对象名 line。<br>
第四行,标签控件,文本为 "IP";单行编辑器,对象名 lineEditIP。<br>
第五行,标签控件,文本为 "Port";单行编辑器,对象名 lineEditPort。<br>
第六行,标签控件,文本为 "HostName";单行编辑器,对象名 lineEditHostName。<br>
第七行,标签控件,文本为 "WorkGroup";单行编辑器,对象名 lineEditWorkGroup。<br>
<br>
界面控件布局很简单,头两行按照水平布局器布局,末尾四行也是水平布局器,窗体的主布局器是垂直布局,得到如下图效果:<br>
<center><img src="images/ch07/ch07-02-07.png" alt="lay1" width="800"></center>
现在界面虽然布局好了,但是打头的标签控件宽度不一样,导致界面不太整齐。<br>
我们选中较宽的 "目的文件" 标签,宽度为 48,选中 "WorkGroup" 标签,宽度是 54,为了让界面更整齐,<span style="font-weight: bold;">我
们把打头的标签控件全部设置最小宽度为 60,留点余量,</span>这样就会得到下图效果:<br>
<center><img src="images/ch07/ch07-02-08.png" alt="lay2" width="800"></center>
这样控件和布局器就设置好了。下面分四次右击为四个按钮,右键菜单选择 "转到槽..." ,都添加 clicked() 信号对应的槽函数:<br>
<center><img src="images/ch07/ch07-02-09.png" alt="lay3"></center>
添加好槽函数之后,保存界面文件,关闭界面文件,回到 QtCreator 代码编辑模式。<br>
首先打开 widget.h 头文件,向里面添加一个新的私有函数,用于解析文本文件里的一行配置项:<br>
<div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;">
</span>WIDGET_H
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#define</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">WIDGET_H</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QWidget></span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">namespace</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">:</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">public</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">Q_OBJECT</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">public</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">explicit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QWidget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span>parent<span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">~</span><span style=" font-style:italic; color:#000000;">Widget</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">slots</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonBrowseSrc_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonLoad_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonBrowseDst_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonSave_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Ui</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//分析一行配置文本,设置到对应的控件里</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">AnalyzeOneLine</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">const</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&</span>baLine<span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#endif</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">WIDGET_H</span></pre>
</div>
最后的 AnalyzeOneLine() 就是新增的函数,其他代码都是 QtCreator 自动生成的。<br>
然后编辑 widget.cpp 文件,添加例子功能代码,先来看看头文件包含和构造函数:<br>
<div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;">
</span><span style=" color:#008000;">"widget.h"</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ui_widget.h"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QDebug></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMessageBox></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QRegExp></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QRegExpValidator></span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//正则表达式验证器,检验IP</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QIntValidator></span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//整数验证器,检验端口</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QFileDialog></span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//打开和保存文件对话框</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QFile></span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//读写文件</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">Widget</span><span style=" color:#000000;">(</span><span
style=" color:#800080;">QWidget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">*</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setupUi</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">);</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IPv4</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">正则表达式,注意</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"\\"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">就是一个反斜杠</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">re</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//新建正则表达式验证器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExpValidator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">reVali</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExpValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">re</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置给</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">lineEditIP</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditIP</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">reVali</span><span
style=" color:#000000;">);</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//新建整数验证器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QIntValidator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">intVali</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QIntValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">0</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">65535</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置给</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">lineEditPort</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditPort</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">intVali</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">Widget</span><span style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
包含的头文件里面,<QRegExp>和<QRegExpValidator> 是正则表达式和正则表达式验证器,用于校验 IPv4
输入,<QIntValidator> 是整数验证器,用于校验端口范围。<QFileDialog>
是文件对话框,用于获取打开或保存的文件名,<QFile> 是文件类。<br>
在构造函数里面,定义了一个 IPv4 正则表达式 re,注意之前 5.2.4 节 netparas
例子也用过这个表达式,当时编的正则表达式代码有点问题,因为其他脚本语言 "\" 不是转义字符,是原始的反斜杠,在 C++ 代码中的字符串,需要用
"\\" 替换 "\" 来表示字符串中的一个反斜杠字符。目前把正则表达式都矫正了,这回是对的了。<br>
<br>
在定义 re 之后,新建正则表达式验证器 reVali,并把验证器设置给 lineEditIP。<br>
接着新建整数验证器 intVali ,设置给 lineEditPort。<br>
构造函数新增的代码就是为了验证 IPv4 格式和端口范围。<br>
<br>
在我们要打开文件时,需要在文件系统里浏览找到这个文件,可以用类似下面的代码实现,就是 "浏览源" 按钮的槽函数:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonBrowseSrc_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取将要打开的文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strSrcName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QFileDialog</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">getOpenFileName</span><span style=" color:#000000;">(</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">this</span><span
style=" color:#000000;">,</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"打开配置文件"</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"."</span><span style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Text</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">files(*.txt);;All</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">files(*)"</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strSrcName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//空字符串不处理,返回</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置源文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditSrcFile</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strSrcName</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
这个函数里最关键的就是 QFileDialog::getOpenFileName() 静态函数,一般只需要设置该静态函数的四个参数:<br>
第一个参数是父窗口指针;第二个是弹出对话框的标题;第三个是弹出对话框默认的开始路径;第四个是文件扩展名过滤字符串。过滤字符串格式就如代码里显示的,多个过
滤器用双分号分隔,扩展名格式放在圆括号内部。<br>
如果找到文件名成功,该函数就会返回正常的文件名字符串,如果用户取消了对话框,那么返回空字符串。<br>
因此需要判断一下对话框的返回字符串是否为空,然后把非空字符串设置到界面的控件显示出来。<br>
<br>
接下来是 "加载配置" 按钮对应的槽函数代码:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonLoad_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取源文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strSrc</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditSrcFile</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strSrc</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">())</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//没设置文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义文件对象</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QFile</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileIn</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strSrc</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断是否正确打开</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileIn</span><span
style=" color:#000000;">.</span><span style=" font-style:italic; color:#000000;">open</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QIODevice</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">ReadOnly</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//打开错误</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"打开错误"</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"打开文件错误:"</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">fileIn</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">errorString</span><span style=" color:#000000;">());</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//不处理文件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读取并解析文件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileIn</span><span
style=" color:#000000;">.</span><span style=" font-style:italic; color:#000000;">atEnd</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读取一行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baLine</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">fileIn</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">readLine</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baLine</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">baLine</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//剔除字符串两端空白</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断是否为注释行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baLine</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">startsWith</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">'#'</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">continue</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//不处理注释行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//正常的设置行,分析这一行的配置项</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">AnalyzeOneLine</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">baLine</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//提示加载完毕</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"加载配置"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"加载配置项完毕!"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
这个槽函数先获取源文件名,判断是否为空,没有文件名就不处理。<br>
有文件名,就根据文件名定义文件类对象 fileIn,<br>
以 QIODevice::ReadOnly 模式打开文件,如果打开失败就报错并返回,<br>
错误信息可以用 fileIn.<span style="font-weight: bold;">errorString()</span> 函数获取。<br>
<br>
如果打开正确,就用 while 循环加载文件的每一行,直到文件结束。<br>
因为配置文件里面的文本行,两端可能有空白字符,先剔除掉两端空白字符,然后判断打头的字符是否为井号,<br>
如果是井号就跳过这个注释行。<br>
如果打头的不是井号,说明是有用的配置行,就调用 AnalyzeOneLine() 分析这一行配置。<br>
<br>
分析完配置文件所有行之后,我们用 QMessageBox::information() 提示已经加载完毕。<br>
<br>
在文本处理时,要注意用户可能输入的空白字符,通常需要把文本两端的空白字符剔除掉再进行后续的判断,QString 类和 QByteArray 类都有
trimmed() 函数实现剔除两端空白字符的功能。<br>
<br>
接着我们看看私有函数 AnalyzeOneLine() 的代码:<br>
<div class="code"><span style=" color:#008000;">//分析一行配置文本,设置到对应的控件里</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">AnalyzeOneLine</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">const</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&</span><span
style=" color:#000000;">baLine</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//按等号分隔</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QList</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QByteArray</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">list</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">baLine</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">split</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">'='</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">list</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">count</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">2</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//分隔之后没有配置值,无法设置</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//配置项名,剔除空格,变为统一的小写名称</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">optionName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">list</span><span style=" color:#000000;">[</span><span style=" color:#000080;">0</span><span
style=" color:#000000;">].</span><span style=" color:#000000;">trimmed</span><span
style=" color:#000000;">().</span><span style=" color:#000000;">toLower</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//配置项的值,只需要剔除空格</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">optionValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">list</span><span style=" color:#000000;">[</span><span style=" color:#000080;">1</span><span
style=" color:#000000;">].</span><span style=" color:#000000;">trimmed</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QString</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">fromLocal8Bit</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">optionValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断哪个配置项</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"ip"</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">optionName</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditIP</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"port"</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">optionName</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditPort</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"hostname"</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">optionName</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditHostName</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"workgroup"</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">optionName</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditWorkGroup</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//如果有其他不相关的配置项名不处理</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
配置文本的每一行都是等号分隔的,左边为配置项名,右边为配置项的数值。<br>
我们直接用 split() 函数切分就行了,切分之后得到列表 list。<br>
判断 list 是否把文本行切成了两段以上,如果少于两端,说明配置行内容不完整,配置项名或数值少了,就不处理。<br>
如果切分后,至少有两端文本,那么把 list[0] 剔除空白,并转为全小写字母,作为配置项名称,转成小写防止用户把配置项名写成大写字母导致与后面的判断不
匹配。<br>
再把 list[1] 剔除两端空白,并构造新的数值字符串 strValue ,用于界面显示。<br>
我们对配置项的名称进行判断,对于 "ip" 、"port"、"hostname"、"workgroup" 四个配置项名,匹配哪个就将数值字符串设置到对应
的控件里面。<br>
如果有不匹配的配置项名,这里没有处理,我们只处理想要的配置项。<br>
<br>
文件打开和加载的代码就是上面那么多。下面来看看如何保存新的配置文件。<br>
获取保存文件名的代码如下所示,就是 "浏览目的" 按钮的槽函数:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonBrowseDst_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取要保存的文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strDstName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QFileDialog</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">getSaveFileName</span><span style=" color:#000000;">(</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">this</span><span
style=" color:#000000;">,</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"保存配置文件"</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"."</span><span style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"Text</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">files(*.txt);;All</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">files(*)"</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strDstName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">())</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//空字符串不处理</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置要保存的文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditDstFile</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strDstName</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
获取保存文件名就用 QFileDialog::getSaveFileName()
静态函数,也是设置四个参数,与打开文件对话框非常类似。注意保存文件对话框会提示是否覆盖已存在的文件,而打开文件对话框总是选择已存在文件进行打开。一般保存文件对话
框都是用 户自己设置不存在的新文件名用于保存文件。<br>
获取到非空的保存文件名字符串之后,设置给 lineEditDstFile 控件显示。<br>
<br>
最后是实际保存各个配置项的函数,就是 "保存配置" 按钮对应的槽函数:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonSave_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取保存文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strSaveName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditDstFile</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取设置值</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditIP</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPort</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditPort</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strHostName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditHostName</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strWorkGroup</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditWorkGroup</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//如果字符串有空串就不写入</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strSaveName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPort</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strHostName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strWorkGroup</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"保存配置"</span><span style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"需要设置好保存文件名和所有配置项数值。"</span><span
style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义文件对象</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QFile</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strSaveName</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//打开</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">.</span><span style=" font-style:italic; color:#000000;">open</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QIODevice</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">WriteOnly</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">|</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QIODevice</span><span style=" color:#000000;">::</span><span
style=" color:#800080;">Truncate</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">|</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QIODevice</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Text</span><span
style=" color:#000000;">))</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"打开文件"</span><span style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"打开目的文件失败:"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">errorString</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//构造字节数组写入</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//ip</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ip</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strIP</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toLocal8Bit</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"\n"</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">write</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//port</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"port</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strPort</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toLocal8Bit</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"\n"</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">write</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//hostname</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"hostname</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strHostName</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toLocal8Bit</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"\n"</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">write</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//workgroup</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">行</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"workgroup</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strWorkGroup</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toLocal8Bit</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"\n"</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileOut</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">write</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//提示保存成功</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"保存配置"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"保存配置项成功!"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
这个槽函数先获取保存文件名和四个配置项的数值字符串,如果有空字符串就不保存,必须填好保存文件名和所有配置项才进行后面操作。<br>
根据保存文件名定义一个 文具类对象 fileOut,<br>
然后以 “写入、清空旧数据、文本” 三个模式同时打开文件,如果打开失败就提示错误消息 fileOut.errorString()。<br>
如果打开成功,就开始写入,定义临时字节数组 baTemp ,<br>
先构造 ip 配置行的前半截,然后把 strIP 转为本地化字符串,并附加上换行符,这样构造了一行配置文本,写入到新配置文件中。<br>
其他三个配置项的行类似构造,然后都写入到新配置文件中。<br>
写入时,换行符要自己添加,因为 write() 函数是不会自动添加换行符的。<br>
写完四行配置文本之后,用 QMessageBox::information() 提示保存配置成功。<br>
<br>
我们生成并运行例子,选择项目文件夹中的 testconf.txt 加载,得到如下图效果:
<center><img src="images/ch07/ch07-02-10.png" alt="run"></center>
保存配置功能这里不截图了,读者可以自己试试看。<br>
这第一个示例是按行读取文本文件,并分析配置项内容。下面第二个例子学习如何按字节块读取结构体形式的文件头。<br>
<br>
<div class="os2">7.2.5 BMP文件头解析示例</div>
<br>
BMP 是比较简单的图片文件,Windows 画图板默认就是以这种格式保存图片。在 MFC 和 Windows 编程的书籍里面有不少关于 BMP
文件头的介绍,这里简单介绍一下。BMP 文件的大致框架如下图所示:<br>
<center><img src="images/ch07/ch07-02-11.png" alt="bmp"></center>
我们本小节关注的就是打头的两个结构体 BMPFileHeader 和 BMPInfoHeader,后面颜色表和像素点数据就不读取了。<br>
其实所有的文件格式都是由各种各样的结构体组成,BMP 也是这样。BMP 文件首先以一个 BMPFileHeader 开始,共14字节,我们按照 Qt
风格,把 BMPFileHeader 定义如下:<br>
<div class="code">//定义文件头 BMPFileHeader,长度14字节<br>
struct BMPFileHeader<br>
{<br>
quint16 bfType; //文件类型,原始两字节 'BM'<br>
quint32 bfSize; //BMP图片文件大小<br>
quint16 bfReserved1; //保留字段1,数值为 0<br>
quint16 bfReserved2; //保留字段2,数值为 0<br>
quint32 bfOffBits;
//像素点数据起始位置,相对于 BMPFileHeader 的偏移量,以字节为单位<br>
};</div>
文件头两个字节就是 'B' 和 'M' ,对应的 bfType 短整形数值为 0x4D42
,读取文件的时候前面的字节会填充到低位字节,所以倒了一下。bfSize 就是图片文件的大小,其他三个字段我们本小节不关心。<br>
<br>
BMP文件第二个部分是图片信息头 BMPInfoHeader,我们把该结构体按 Qt 风格定义如下:<br>
<div class="code">//定义信息头 BMPInfoHeader,长度40字节<br>
struct BMPInfoHeader<br>
{<br>
quint32 biSize; //本结构体长度,占用字节数<br>
quint32 biWidth; //图片宽度,像素点数<br>
quint32 biHeight; //图片高度,像素点数<br>
quint16 biPlanes; //目标设备级别,数值为 1 (图层数或叫帧数)<br>
quint16 biBitCount; //每个像素点占用的位数,就是颜色深度 (位深度)<br>
quint32 biCompression; //是否压缩,一般为 0 不压缩<br>
quint32 biSizeImage;
//像素点数据总共占用的字节数,因为每行像素点数据末尾会按4字节对齐,对齐需要的字节数也算在内<br>
quint32 biXPelsPerMeter;//水平分辨率,像素点数每米(== 水平DPI *
39.3701)<br>
quint32 biYPelsPerMeter;//垂直分辨率,像素点数每米(== 垂直DPI *
39.3701)<br>
quint32 biClrUsed;
//颜色表中实际用到的颜色数目<br>
quint32 biClrImportant;//图片显示中重要颜色数目<br>
};</div>
这里面大部分字段比较专业,如果没学图像处理课程可能不太好理解,本小节主要关心图片宽度 biWidth、高度 biHeight、帧数
biPlanes、颜色深度 biBitCount、水平分辨率 biXPelsPerMeter、垂直分辨率
biYPelsPerMeter。我们例子程序解析之后的 BMP 头部信息大致与 Windows 系统对 BMP 文件属性的描述类似:<br>
<center><img src="images/ch07/ch07-02-12.png" alt="bmpattr"></center>
示例图片 logo.bmp 可以到网站目录里下载:<br>
<a href="https://lug.ustc.edu.cn/sites/qtguide/QtProjects/ch07/bmpheader/" target="new">
https://lug.ustc.edu.cn/sites/qtguide/QtProjects/ch07/bmpheader/ </a> <br>
<br>
下面开始这个例子,我们重新打开 QtCreator,新建一个 Qt Widgets Application 项目,在新建项目的向导里填写:<br>
①项目名称 bmpheader,创建路径 D:\QtProjects\ch07,点击下一步;<br>
②套件选择里面选择全部套件,点击下一步;<br>
③基类选择 QWidget,点击下一步;<br>
④项目管理不修改,点击完成。<br>
建好项目之后,打开窗体 widget.ui 文件,进入设计模式,把主窗体大小设置为 480*360 。<br>
然后按照下图排布,拖入三大行控件:<br>
<center><img src="images/ch07/ch07-02-13.png" alt="ui" width="800"></center>
第一行控件:标签控件,文本为 "文件名";单行编辑器,对象名为 lineEditName;按钮控件,文本为 "浏览",对象名为
pushButtonBrowse。第一行按照水平布局器布局。<br>
第二行控件:按钮控件,文本为 "显示图片",对象名为 pushButtonShowPic;水平弹簧条,对象名
horizontalSpacer;按钮控件,文本为 "读取头部",对象名为 pushButtonReadHeader。第二行控件也是按水平布局器布局。<br>
<br>
第三行控件按如下步骤拖动:<br>
① 拖一个 Scroll Area 滚动区域控件到左边,对象名默认为 scrollArea,把它拉大,占据左边大部分区域;<br>
② 拖一个标签控件到 scrollArea 控件内部,标签文本为 "显示图片区域",对象名为 labelShowPic;<br>
③ 拖一个 Text Browser 控件到右边空白区域,这个丰富文本浏览控件对象名默认为
textBrowser,这个文本浏览控件用于显示我们程序解析的 BMP 头部信息。<br>
<br>
第三行的控件就是这些,关于第三行布局,按下面来操作:<br>
● 点击选中 labelShowPic 标签,设置它的 sizePolicy 属性中水平策略和垂直策略都为 <span style="font-weight: bold;">Expanding</span>,
设置它的 alignment 属性为 水平的 <span style="font-weight: bold;">AlignHCenter </span>和
垂直的 <span style="font-weight: bold;">AlignVCenter</span>:<br>
<center><img src="images/ch07/ch07-02-14.png" alt="label" width="800"></center>
● 点击选中 scrollArea 控件,点击上面的水平布局按钮,这样是为滚动区域内部设置主布局器,滚动区域内的主布局器只有一个标签控件
labelShowPic,这个标签控件会填充满整个滚动区域。<br>
设置滚动区域内部主布局器之后,滚动区域会自动缩小,我们把滚动区域重新拉大,大概拉大成下图的样子,然后设置scrollArea 控件 sizePolicy
属性里面的水平伸展为 3,如下图所示:<br>
<center><img src="images/ch07/ch07-02-15.png" alt="scrollarea" width="800"></center>
● 点击选中右边的 textBrowser 控件,然后设置它的 sizePolicy 属性里面的水平伸展为 1 ,如下图所示:<br>
<center><img src="images/ch07/ch07-02-16.png" alt="textbrowser" width="800"></center>
● 按照上面的设置后,第三行的控件细节就配置好了,我们选中第三行的 scrollArea 和 textBrowser
,点击上面的水平布局按钮,进行水平布局,这时候滚动区域控件和文本浏览控件自动按照 3:1 比例分配水平空间:<br>
<center><img src="images/ch07/ch07-02-17.png" alt="lay3" width="800"></center>
● 我们点击主窗体的空白区域,只选中主窗体,而不选中任何控件,点击上面的垂直布局按钮,为主窗体设置主布局器:<br>
<center><img src="images/ch07/ch07-02-18.png" alt="mainlayout" width="800"></center>
<br>
按照上面设计好界面之后,为三个按钮都添加 clicked() 信号对应的槽函数:<br>
<center><img src="images/ch07/ch07-02-19.png" alt="slot"></center>
添加好三个槽函数之后,我们保存界面文件,关闭界面文件,回到 QtCreator 编辑模式。<br>
<br>
我们打开 widget.h 头文件,向其中添加结构体声明代码:<br>
<div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;">
</span>WIDGET_H
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#define</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">WIDGET_H</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QWidget></span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#008000;">//结构体都按</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">字节补齐,因为编译器默认按</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">4</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">字节补齐,导致</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">BMPFileHeader</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">长度</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">16,16是错的</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#pragma</span><span style=" color:#c0c0c0;"> </span>pack(1)</pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#008000;">//定义文件头</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">BMPFileHeader,长度14字节</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">struct</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">BMPFileHeader</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint16</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">bfType</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//文件类型,原始两字节</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">'BM'</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">bfSize</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//BMP图片文件大小</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint16</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">bfReserved1</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//保留字段1,数值为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">0</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint16</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">bfReserved2</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//保留字段2,数值为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">0</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">bfOffBits</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//像素点数据起始位置,相对于</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">BMPFileHeader</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">的偏移量,以字节为单位</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#008000;">//定义信息头</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">BMPInfoHeader,长度40字节</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">struct</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">BMPInfoHeader</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biSize</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//本结构体长度,占用字节数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biWidth</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//图片宽度,像素点数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biHeight</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//图片高度,像素点数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint16</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biPlanes</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//目标设备级别,数值为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">(图层数或叫帧数)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint16</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biBitCount</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//每个像素点占用的位数,就是颜色深度</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">(位深度)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biCompression</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//是否压缩,一般为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">0</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">不压缩</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biSizeImage</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//像素点数据总共占用的字节数,因为每行像素点数据末尾会按4字节对齐,对齐需要的字节数也算在内</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biXPelsPerMeter</span><span
style=" color:#000000;">;</span><span style=" color:#008000;">//水平分辨率,像素点数每米(==</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">水平DPI</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">*</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">39.3701)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biYPelsPerMeter</span><span
style=" color:#000000;">;</span><span style=" color:#008000;">//垂直分辨率,像素点数每米(==</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">垂直DPI</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">*</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">39.3701)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biClrUsed</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//颜色表中实际用到的颜色数目</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">quint32</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">biClrImportant</span><span
style=" color:#000000;">;</span><span style=" color:#008000;">//图片显示中重要颜色数目</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">namespace</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">:</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">public</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">Q_OBJECT</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">public</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">explicit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QWidget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span>parent<span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">~</span><span style=" font-style:italic; color:#000000;">Widget</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">slots</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonBrowse_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonShowPic_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonReadHeader_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Ui</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#endif</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">WIDGET_H</span></pre>
</div>
头文件后半部分是 Widget 类的代码,是自动生成的。我们主要看看前半截的结构体声明。在声明结构体之前,有一句代码:<br>
<div class="code">#pragma pack(1)</div>
这句代码的意思就是告知编译器对结构体里面的变量按 1 字节对齐,一般编译器默认是 4 字节对齐。4字节对齐导致 BMPFileHeader 里面的
bfType 占用 4 字节,然后这个结构体就变成 16 字节长度。16字节长度是错误的设定,因为真正的头部只有 14
字节,必须引入上面一句对齐调整代码,后面的文件头读写才会正常。<br>
<br>
BMPFileHeader 和 BMPInfoHeader 结构体声明照着上面代码抄就行了,具体含义不讲了,一般也就图像处理方面的课程才用到,这里就当它
们是一堆变量就行了。这两个结构体在 BMP 文件是顺序存放的,所以 BMP
文件结构是比较简单的,读者以后编程有可能遇到其他复杂文件格式,可能出现结构体嵌套、链接之类的,就比较麻烦了。<br>
<br>
接下来我们编辑 widget.cpp,添加功能代码,首先是头文件包含和构造函数:<br>
<div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;">
</span><span style=" color:#008000;">"widget.h"</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ui_widget.h"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QDebug></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMessageBox></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QFileDialog></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QFile></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QPixmap></span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">Widget</span><span style=" color:#000000;">(</span><span
style=" color:#800080;">QWidget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">*</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setupUi</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//打印结构体大小</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">qDebug</span><span
style=" color:#000000;">()<<</span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"BFH:</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">B"</span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">sizeof</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">BMPFileHeader</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">qDebug</span><span
style=" color:#000000;">()<<</span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"BIH:</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">B"</span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">sizeof</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">BMPInfoHeader</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">Widget</span><span style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
头文件 <QFileDialog> 是文件打开或保存的对话框,<QFile> 是文件类,<QPixmap>
是像素图的类,用于加载图片显示到标签控件。<br>
在构造函数里添加了的调试打印代码,打印两个结构体的字节数,程序运行时 BMPFileHeader 应该为 14 字节,BMPInfoHeader 应该为
40 字节。<br>
<br>
然后我们来看看 "浏览" 按钮对应的槽函数代码:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonBrowse_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取要打开的图片文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QFileDialog</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">getOpenFileName</span><span style=" color:#000000;">(</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">this</span><span
style=" color:#000000;">,</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"打开BMP"</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"."</span><span style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">Files(*.bmp);;All</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">Files(*)"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">())</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditName</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
这个槽函数代码比较简单,就调用 QFileDialog::getOpenFileName() 获取将要打开的文件名,获取到了非空文件名之后显示到
lineEditName 控件里面。<br>
<br>
接下来是 "显示图片" 按钮对应的槽函数代码:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonShowPic_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取图片文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//在</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">labelShowPic</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">标签控件显示图片</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">labelShowPic</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setPixmap</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QPixmap</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
这个槽函数先获取图片文件名 strName,如果文件名非空,那就把文件加载为 QPixmap 像素图,然后设置给 labelShowPic
标签控件,显示该图片。<br>
<br>
最后是 "读取头部" 按钮对应的槽函数代码:<br>
<div class="code"><span style=" color:#808000;">void</span><span style=" color:#c0c0c0;">
</span><span style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">on_pushButtonReadHeader_clicked</span><span style=" color:#000000;">()</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取图片文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditName</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//没文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//现在有文件名</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QFile</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileIn</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strName</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//只读模式打开</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileIn</span><span
style=" color:#000000;">.</span><span style=" font-style:italic; color:#000000;">open</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QIODevice</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">ReadOnly</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"打开文件"</span><span style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"打开文件失败:"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileIn</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">errorString</span><span
style=" color:#000000;">());</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//现在正确打开了</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">文件头</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">BMPFileHeader</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bfh</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">信息头</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">BMPInfoHeader</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bih</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读取</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">文件头和信息头</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">qint64</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nReadBFH</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">fileIn</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">read</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">(</span><span style=" color:#808000;">char</span><span style=" color:#000000;">*)&</span><span
style=" color:#000000;">bfh</span><span style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">sizeof</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">bfh</span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">qint64</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nReadBIH</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">fileIn</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">read</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">(</span><span style=" color:#808000;">char</span><span style=" color:#000000;">*)&</span><span
style=" color:#000000;">bih</span><span style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">sizeof</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">bih</span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断读取字节数对不对</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">(</span><span
style=" color:#000000;">nReadBFH</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;"><</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">sizeof</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">bfh</span><span style=" color:#000000;">))</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">||</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">(</span><span style=" color:#000000;">nReadBIH</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">sizeof</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">bih</span><span style=" color:#000000;">))</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">warning</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"读取</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP"</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"读取</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">头部失败,头部字节数不够!"</span><span
style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//字节数目够了,构造信息字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"文件名:%1\r\n\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">strName</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//开始判断</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bfh</span><span
style=" color:#000000;">.</span><span style=" color:#800000;">bfType</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0x4D42</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"类型:不是</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">图片\r\n"</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//是正常的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">图片</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"类型:是</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">BMP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">图片\r\n"</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读取</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">bih</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">里面的信息</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"宽度:%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bih</span><span style=" color:#000000;">.</span><span
style=" color:#800000;">biWidth</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"高度:%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bih</span><span style=" color:#000000;">.</span><span
style=" color:#800000;">biHeight</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"水平分辨率:%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">DPI\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">)(</span><span style=" color:#000000;">bih</span><span style=" color:#000000;">.</span><span
style=" color:#800000;">biXPelsPerMeter</span><span style=" color:#000000;">/</span><span
style=" color:#000080;">39.3701</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"垂直分辨率:%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">DPI\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">)(</span><span style=" color:#000000;">bih</span><span style=" color:#000000;">.</span><span
style=" color:#800000;">biYPelsPerMeter</span><span style=" color:#000000;">/</span><span
style=" color:#000080;">39.3701</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"颜色深度:%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">位\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bih</span><span style=" color:#000000;">.</span><span
style=" color:#800000;">biBitCount</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"帧数:%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">bih</span><span style=" color:#000000;">.</span><span style=" color:#800000;">biPlanes</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strTemp</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示信息串到</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">textBrowser</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
</div>
这个槽函数首先获取文件名,判断文件名是否为空。<br>
对于非空文件名,定义文件对象 fileIn,并以只读模式打开文件,如果打开失败就报错返回。<br>
在打开成功之后,定义 BMP 文件头 bfh 和信息头 bih,从文件中依次读取数据填充到这两个结构体中。<br>
然后判断读取的字节数目够不够,如果读取的字节数不够,说明文件格式出错,就报错返回。<br>
<br>
读取两个结构体对象 bfh 和 bih 字节数目够了,那进行下一步的判断:<br>
先判断 bfh.bfType 是否为 0x4D42,如果不是这个数值说明不是 BMP 图片文件,填充信息到 strInfo 。<br>
如果 bfh.bfType 是 0x4D42,说明这个文件是 BMP 格式的,我们开始逐个读取信息头 bih 里面的字段,<br>
对于宽度、高度、颜色深度、帧数直接用对应字段数值即可;<br>
水平和垂直分辨率比较特殊,BMP 里面单位是 像素点数每米,而操作系统里常见的是 DPI,是每英尺的点数。<br>
通常这两个单位转换就是把 BMP 里的分辨率数值除以 39.3701 ,就得到 DPI,代码里可以看到简单转换的过程。<br>
<br>
第二个例子的代码就是上面那么多,我们生成并运行例子,打开 logo.bmp ,点击 "显示图片" 和 "读取头部" 按钮,可以看到程序解析 BMP
头部结果:<br>
<center><img src="images/ch07/ch07-02-20.png" alt="run"></center>
读者可以把例子程序结果与 Windows 系统里面的 BMP 文件属性做对比。<br>
<br>
本节示例代码中 QFile 对象都没有调用过 close() 函数,因为这些 QFile
对象是在函数栈上分配的,函数调用结束时,文件对象会自动销毁,就在对象销毁时文件自动被关闭,不需要手动调用 close() 函数。<br>
关于 QFile 类的功能示范就到这里,我们下一节学习文本流 QTextStream 的用法。<br>
<br>
<br>
<br>
<table style="text-align: left; width: 100%;" border="0" cellpadding="2" cellspacing="2">
<tbody>
<tr>
<td style="width: 40%;">
<div style="text-align: center;"><a href="ch07-01.htm"><img class="pic"
style="width: 32px; height: 32px;" alt="prev" src="images/pics/prev.png"></a></div>
</td>
<td style="width: 20%;">
<div style="text-align: center;"><a href="contents.htm"><img class="pic"
style="width: 32px; height: 32px;" alt="contents" src="images/pics/contents.png"></a></div>
</td>
<td style="width: 40%;">
<div style="text-align: center;"><a href="ch07-03.htm"><img class="pic"
style="width: 32px; height: 32px;" alt="next" src="images/pics/next.png"></a></div>
</td>
</tr>
</tbody>
</table>
</body>
</html>
此处可能存在不合适展示的内容,页面不予展示。您可通过相关编辑功能自查并修改。
如您确认内容无涉及 不当用语 / 纯广告导流 / 暴力 / 低俗色情 / 侵权 / 盗版 / 虚假 / 无价值内容或违法国家有关法律法规的内容,可点击提交进行申诉,我们将尽快为您处理。