Qt对Html富文本支持的控件以及QLabel两种打开超链接的方式

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原创文章，欢迎转载。转载请注明：转载自 祥的博客

原文链接：https://blog.csdn.net/humanking7/article/details/80685893

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1.说明

Qt的文本窗体部件能够显示富文本，使用HTML4 标记。能够以这种方式显示富文本的窗体控件有： QTextDocument, 以及 QLabel and QTextEdit。

Qt’s text widgets are able to display rich text, specified using a subset of HTML4 markup. Widgets that use QTextDocument, such as QLabel and QTextEdit, are able to display rich text specified in this way.

2.演示

2.1. 代码

#include 
#include 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QString str;
    str = QString("
Hello Qt!
My CSDN blog: https://blog.csdn.net/humanking7 
");
    QLabel *lab = new QLabel(str);
    lab->setOpenExternalLinks(true);//如果没有这句，就只能通过linkActivated信号，连接到自定义槽函数中打开      
    lab->setWindowTitle("Test Html support");
    lab->show();

    return a.exec();
}

2.2. 关于打开超链接的两种方式说明

1. 简单方式，用Qt自带的setOpenExternalLinks(true)函数进行设置；
2. 用通过linkActivated信号，连接到自定义槽函数中打开超链接。

用第二种方式实现超链接[重新继承了一个QDialog类，在里面进行操作]：

文件1. main.cpp

#include 
#include "dlgShow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    dlgShow* w = new dlgShow();
    w->show();
    return a.exec();
}

文件2. dlgshow.h

#ifndef DLGSHOW_H
#define DLGSHOW_H

#include 
#include 
class dlgShow : public QDialog
{
    Q_OBJECT

public:
    dlgShow(QWidget *parent = 0);
    ~dlgShow();

protected slots:
    void openURL(QString url);
};

#endif // DLGSHOW_H

文件3. dlgshow.cpp

#include 
#include 
#include "dlgshow.h"

dlgShow::dlgShow(QWidget *parent)
    : QDialog(parent)
{   
    setWindowTitle("Dlg:Test Html support");//设置标题
    QString str;
    str = QString("
Hello Qt!
My CSDN blog: https://blog.csdn.net/humanking7 
");
    QLabel *lab = new QLabel(str, this);//添加label
    lab->show();
    //绑定超链接与信号槽
    connect(lab, SIGNAL(linkActivated(QString)), this, SLOT(openURL(QString)));

}

void dlgShow::openURL(QString url)
{//槽函数
    //打开对应url的网址
    QDesktopServices::openUrl(QUrl(url));
}

dlgShow::~dlgShow()
{

}

3.支持的标签 Tags

下表列出了Qt富文本引擎支持的Html标签：

Tag	Description	Comment
a	Anchor or link	Supports the href and name attributes.
address	Address
b	Bold
big	Larger font
blockquote	Indented paragraph
body	Document body	Supports the bgcolor attribute, which can be a Qt color name or a #RRGGBB color specification.
br	Line break
center	Centered paragraph
cite	Inline citation	Same as i.
code	Code	Same as tt.
dd	Definition data
dfn	Definition	Same as i.
div	Document division	Supports the standard block attributes.
dl	Definition list	Supports the standard block attributes.
dt	Definition term	Supports the standard block attributes.
em	Emphasized	Same as i.
font	Font size, family, and/or color	Supports the following attributes: size, face, and color (Qt color names or #RRGGBB).
h1	Level 1 heading	Supports the standard block attributes.
h2	Level 2 heading	Supports the standard block attributes.
h3	Level 3 heading	Supports the standard block attributes.
h4	Level 4 heading	Supports the standard block attributes.
h5	Level 5 heading	Supports the standard block attributes.
h6	Level 6 heading	Supports the standard block attributes.
head	Document header
hr	Horizontal line	Supports the width attribute, which can be specified as an absolute or relative (%) value.
html	HTML document
i	Italic
img	Image	Supports the src, source (for Qt 3 compatibility), width, and height attributes.
kbd	User-entered text
meta	Meta-information	If a text encoding is specified using the meta tag, it is picked up by Qt::codecForHtml(). Likewise, if an encoding is specified to QTextDocument::toHtml(), the encoding is stored using a meta tag, for example:
li	List item
nobr	Non-breakable text
ol	Ordered list	Supports the standard list attributes.
p	Paragraph	Left-aligned by default. Supports the standard block attributes.
pre	Preformated text
qt	Qt rich-text document	Synonym for html. Provided for compatibility with earlier versions of Qt.
s	Strikethrough
samp	Sample code	Same as tt.
small	Small font
span	Grouped elements
strong	Strong	Same as b.
sub	Subscript
sup	Superscript
table	Table	Supports the following attributes: border, bgcolor (Qt color names or #RRGGBB), cellspacing, cellpadding, width (absolute or relative), and height.
tbody	Table body	Does nothing.
td	Table data cell	Supports the standard table cell attributes.
tfoot	Table footer	Does nothing.
th	Table header cell	Supports the standard table cell attributes.
thead	Table header	If the thead tag is specified, it is used when printing tables that span multiple pages.
title	Document title	The value specified using the title tag is available through QTextDocument::metaInformation().
tr	Table row	Supports the bgcolor attribute, which can be a Qt color name or a #RRGGBB color specification.
tt	Typewrite font
u	Underlined
ul	Unordered list	Supports the standard list attributes.
var	Variable	Same as i.

4. 对CSS的支持

下表列出了Qt富文本引擎支持的css：

Property	Values	Description
background-color		Background color for elements
background-image		Background image for elements
color		Text foreground color
font-family		Font family name
font-size	[ small	medium
font-style	[ normal	italic
font-weight	[ normal	bold
text-decoration	none	[ underline
font	[ [ <’font-style’>
text-indent	px	First line text indentation in pixels
white-space	normal	pre
margin-top	px	Top paragraph margin in pixels
margin-bottom	px	Bottom paragraph margin in pixels
margin-left	px	Left paragraph margin in pixels
margin-right	px	Right paragraph margin in pixels
padding-top	px	Top table cell padding in pixels
padding-bottom	px	Bottom table cell padding in pixels
padding-left	px	Left table cell padding in pixels
padding-right	px	Right table cell padding in pixels
padding	px	Shorthand for setting all the padding properties at once.
vertical-align	baseline	sub
border-color		Border color for text tables.
border-style	none	dotted
background	[ <’background-color’>
page-break-before	[ auto	always ]
page-break-after	[ auto	always ]
float	[ left	right
text-transform	[ uppercase	lowercase ]
font-variant	small-caps	Perform the smallcaps transformation on the text prior to displaying it.
word-spacing	px	Specifies an alternate spacing between each word.

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