学习重要的几个QWidget和QFrame子类

转自：http://blog.sina.com.cn/s/blog_825442790100x1ek.html

本文档包括，之前一些没有讲解的QWidget子类和QFrame子类，以及没有详细介绍的几个类，这里在拿出来再详细讲解一下！

编辑时间：2011年9月12日
更新时间：2011年9月14日
更新作者：
西南石油大学计算机科学学院
乐程软件工作室刘红

内容概述：
文档包括的内容包括，QTextEdit类、详细讲解！

 

一、QTextEdit类（及其兄弟类QPlainTextEdit、其子类）
1、对于这些类，主要是用来做文本编辑这一块的。
对于核心成熟的类，QTextEdit类，我们先来了解它的一些类成员：
几个类属性设置函数：
void setAcceptRichText ( bool accept )//设置是否显示富文本
void setAutoFormatting ( AutoFormatting features )
void setCurrentCharFormat ( const QTextCharFormat & format )
void setCursorWidth ( int width )
void setDocument ( QTextDocument * document )
void setDocumentTitle ( const QString & title )
void setExtraSelections ( const QList<ExtraSelection> & selections )
void setLineWrapColumnOrWidth ( int w )
void setLineWrapMode ( LineWrapMode mode )
void setOverwriteMode ( bool overwrite )
void setReadOnly ( bool ro )//设置是否可读
void setTabChangesFocus ( bool b )
void setTabStopWidth ( int width )
void setTextCursor ( const QTextCursor & cursor )
void setTextInteractionFlags ( Qt::TextInteractionFlags flags )
void setUndoRedoEnabled ( bool enable )
void setWordWrapMode ( QTextOption::WrapMode policy )
几个文本操作函数：//这是槽函数
void append ( const QString & text )
void clear ()
void copy ()
void cut ()
void insertHtml ( const QString & text )
void insertPlainText ( const QString & text )
void paste ()
void redo ()
void scrollToAnchor ( const QString & name )
void selectAll ()
void undo ()
几个文本设置函数：//这是槽函数
void setAlignment ( Qt::Alignment a )
void setCurrentFont ( const QFont & f )
void setFontFamily ( const QString & fontFamily )
void setFontItalic ( bool italic )
void setFontPointSize ( qreal s )
void setFontUnderline ( bool underline )
void setFontWeight ( int weight )
void setHtml ( const QString & text )
void setPlainText ( const QString & text )
void setText ( const QString & text )
void setTextBackgroundColor ( const QColor & c )
void setTextColor ( const QColor & c )
以下几个是信号函数：
Signals

void copyAvailable ( bool yes )
void currentCharFormatChanged ( const QTextCharFormat & f )
void cursorPositionChanged ()
void redoAvailable ( bool available )
void selectionChanged ()
void textChanged ()
void undoAvailable ( bool available )

2、我们再看看，Qt help里的一长段的描述：
Using QTextEdit as an Editor

All the information about using QTextEdit as a display widget also applies here.

The current char format's attributes are set with setFontItalic(), setFontWeight(), setFontUnderline(), setFontFamily(), setFontPointSize(), setTextColor() and setCurrentFont(). The current paragraph's alignment is set with setAlignment().

Selection of text is handled by the QTextCursor class, which provides functionality for creating selections, retrieving the text contents or deleting selections. You can retrieve the object that corresponds with the user-visible cursor using the textCursor() method. If you want to set a selection in QTextEdit just create one on a QTextCursor object and then make that cursor the visible cursor using setTextCursor(). The selection can be copied to the clipboard with copy(), or cut to the clipboard with cut(). The entire text can be selected using selectAll().

When the cursor is moved and the underlying formatting attributes change, the currentCharFormatChanged() signal is emitted to reflect the new attributes at the new cursor position.

QTextEdit holds a QTextDocument object which can be retrieved using the document() method. You can also set your own document object using setDocument(). QTextDocument emits a textChanged() signal if the text changes and it also provides a isModified() function which will return true if the text has been modified since it was either loaded or since the last call to setModified with false as argument. In addition it provides methods for undo and redo.

3、了解以上这些之后，我们就可以行动了。
我这里举四个例子，其中一个是我自己编写的。
示例1：我自己写的一个简单的例子.
【1】新建一个空工程，命名为addText，添加main.cpp文件，添加一个类MainWindow，继承于QTextEdit类。
【2】添加main.cpp文件代码如下：
#include <QApplication>
#include "mainwindow.h"

int main(int argc,char *argv[])
{
    QApplication app(argc,argv);
    MainWindow window;
    window.show();
    return app.exec();
}
【3】添加mainwindow.h文件中代码如下：
添加类定义中的代码：
public slots:
    void insertText();
private:
    QTextEdit *edit;
    QPushButton *button;
添加类声明：
QT_BEGIN_NAMESPACE
class QTextEdit;
class QPushButton;
QT_END_NAMESPACE

【4】添加mainwindow.cpp文件代码如下：
添加构造函数代码如下：
    edit = new QTextEdit;

    button = new QPushButton;
    button->setText(tr("liuhong"));
    connect(button,SIGNAL(clicked()),this,SLOT(insertText()));

    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(edit);
    layout->addWidget(button);
    setLayout(layout);
添加共有槽函数代码：
void MainWindow::insertText()
{
    edit->insertPlainText(button->text());
}
同时记得添加头文件：
#include <QtGui>

这是一个比较简单的例子，看懂没多大的困难，接下来的几个例子，可能看懂有一定的困难。

示例2：code editor
【1】新建一个空工程，命名为CodeEditor，添加main.cpp文件，添加CodeEditor类，继承于QPlainTextEdit类（和QTextEdit同属QAbstractScrollAre类）。

注：QAbstractScrollAre类是继承于QFrame类的。
【2】添加main.cpp文件的代码如下：
#include <QApplication>
#include "codeeditor.h"

int main(int argv, char **args)
{
    QApplication app(argv, args);

    CodeEditor editor;
    editor.setWindowTitle(QObject::tr("Code Editor Example"));
    editor.show();

    return app.exec();
}
【2】添加codeeditor.h文件中的类定义代码：
public:
    void lineNumberAreaPaintEvent(QPaintEvent *event);//绘画事件
    int lineNumberAreaWidth();//显示数字的区域大小

protected:
    void resizeEvent(QResizeEvent *event);//固定大小事件

private slots://私有槽函数
    void updateLineNumberAreaWidth(int newBlockCount);//更新显示数字区域的宽度
    void highlightCurrentLine();//高亮的行
    void updateLineNumberArea(const QRect &, int);//更新高亮区域

private:
    QWidget *lineNumberArea;//我们可以看出，显示数字的是一个QWidget类

记得同时添加类声明：
QT_BEGIN_NAMESPACE
class QPaintEvent;
class QResizeEvent;
class QSize;
class QWidget;
QT_END_NAMESPACE

这里我们还在这个类里，额外添加了一个类定义：
class LineNumberArea : public QWidget
{
public:
    LineNumberArea(CodeEditor *editor) : QWidget(editor) {
        codeEditor = editor;
    }

    QSize sizeHint() const {
        return QSize(codeEditor->lineNumberAreaWidth(), 0);
    }

protected:
    void paintEvent(QPaintEvent *event) {
        codeEditor->lineNumberAreaPaintEvent(event);
    }

private:
    CodeEditor *codeEditor;
};

【3】添加codeeditor.cpp文件代码如下：
添加构造函数代码如下：
    lineNumberArea = new LineNumberArea(this);//定义lineNumberArea对象

    connect(this, SIGNAL(blockCountChanged(int)), this, SLOT(updateLineNumberAreaWidth(int)));
    connect(this, SIGNAL(updateRequest(QRect,int)), this, SLOT(updateLineNumberArea(QRect,int)));
    connect(this, SIGNAL(cursorPositionChanged()), this, SLOT(highlightCurrentLine()));

    updateLineNumberAreaWidth(0);//开始设置为零
    highlightCurrentLine();//高亮第一行

//这里我们看到了，QPainTextEdit类的三个信号函数，blockCountChanged(int)，updateRequest(QRect,int)，cursorPositionChanged()。

添加其它函数代码如下：
int CodeEditor::lineNumberAreaWidth()
{
    int digits = 1;
    int max = qMax(1, blockCount());
    while (max >= 10) {
        max /= 10;
        ++digits;
    }

    int space = 3 + fontMetrics().width(QLatin1Char('9')) * digits;

    return space;
}

void CodeEditor::updateLineNumberAreaWidth(int )
{
    setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}

void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
    if (dy)
        lineNumberArea->scroll(0, dy);
    else
        lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());

    if (rect.contains(viewport()->rect()))
        updateLineNumberAreaWidth(0);
}

void CodeEditor::resizeEvent(QResizeEvent *e)
{
    QPlainTextEdit::resizeEvent(e);

    QRect cr = contentsRect();
    lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}

void CodeEditor::highlightCurrentLine()
{
    QList<QTextEdit::ExtraSelection> extraSelections;

    if (!isReadOnly()) {
        QTextEdit::ExtraSelection selection;
       
        QColor lineColor = QColor(Qt::yellow).lighter(160);

        selection.format.setBackground(lineColor);
        selection.format.setProperty(QTextFormat::FullWidthSelection, true);
        selection.cursor = textCursor();
        selection.cursor.clearSelection();
        extraSelections.append(selection);
    }

    setExtraSelections(extraSelections);
}

void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
    QPainter painter(lineNumberArea);//绘制lineNumberArea对象
    painter.fillRect(event->rect(), Qt::lightGray);//填充背景色为淡灰色

    QTextBlock block = firstVisibleBlock();
    int blockNumber = block.blockNumber();
    int top = (int) blockBoundingGeometry(block).translated(contentOffset()).top();
    int bottom = top + (int) blockBoundingRect(block).height();

    while (block.isValid() && top <= event->rect().bottom()) {
        if (block.isVisible() && bottom >= event->rect().top()) {
            QString number = QString::number(blockNumber + 1);
            painter.setPen(Qt::black);
            painter.drawText(0, top, lineNumberArea->width(), fontMetrics().height(),
                             Qt::AlignRight, number);
        }

        block = block.next();
        top = bottom;
        bottom = top + (int) blockBoundingRect(block).height();
        ++blockNumber;
    }
}

这里我是有点糊涂了，这是怎么一回事呢？？？
我不能做出解释，请教高手。

示例3：Text Edit Application
【1】新建一个空工程，添加main.cpp文件，添加一个类MainWindow类，继承于 QMainWindow类。
【2】添加main.cpp文件代码如下：
#include <QApplication>

#include "mainwindow.h"

int main(int argc, char *argv[])
{
    Q_INIT_RESOURCE(application);

    QApplication app(argc, argv);
    app.setOrganizationName("Trolltech");
    app.setApplicationName("Application Example");
    MainWindow mainWin;
    mainWin.show();
    return app.exec();
}
【3】添加资源，命名为images。添加特定的资源。
【4】添加mainwindow.h文件代码如下：
添加类定义代码如下：
protected:
    void closeEvent(QCloseEvent *event);

private slots:
    void newFile();
    void open();
    bool save();
    bool saveAs();
    void about();
    void documentWasModified();

private:
    void createActions();
    void createMenus();
    void createToolBars();
    void createStatusBar();

    void readSettings();
    void writeSettings();
    bool maybeSave();
    void loadFile(const QString &fileName);
    bool saveFile(const QString &fileName);
    void setCurrentFile(const QString &fileName);
    QString strippedName(const QString &fullFileName);

    QPlainTextEdit *textEdit;
    QString curFile;

    QMenu *fileMenu;
    QMenu *editMenu;
    QMenu *helpMenu;
    QToolBar *fileToolBar;
    QToolBar *editToolBar;
    QAction *newAct;
    QAction *openAct;
    QAction *saveAct;
    QAction *saveAsAct;
    QAction *exitAct;
    QAction *cutAct;
    QAction *copyAct;
    QAction *pasteAct;
    QAction *aboutAct;
    QAction *aboutQtAct;
添加类声明如下：
QT_BEGIN_NAMESPACE
class QAction;
class QMenu;
class QPlainTextEdit;
QT_END_NAMESPACE
【5】添加mainwindow.cpp文件中代码如下：
添加构造函数代码如下：
    textEdit = new QPlainTextEdit;
    setCentralWidget(textEdit);

    createActions();
    createMenus();
    createToolBars();
    createStatusBar();

    readSettings();

    connect(textEdit->document(), SIGNAL(contentsChanged()),
            this, SLOT(documentWasModified()));

    setCurrentFile("");
    setUnifiedTitleAndToolBarOnMac(true);
添加其它函数代码如下：
void MainWindow::closeEvent(QCloseEvent *event)
{
    if (maybeSave()) {
        writeSettings();
        event->accept();
    } else {
        event->ignore();
    }
}

void MainWindow::newFile()
{
    if (maybeSave()) {
        textEdit->clear();
        setCurrentFile("");
    }
}

void MainWindow::open()
{
    if (maybeSave()) {
        QString fileName = QFileDialog::getOpenFileName(this);
        if (!fileName.isEmpty())
            loadFile(fileName);
    }
}

bool MainWindow::save()
{
    if (curFile.isEmpty()) {
        return saveAs();
    } else {
        return saveFile(curFile);
    }
}

bool MainWindow::saveAs()
{
    QString fileName = QFileDialog::getSaveFileName(this);
    if (fileName.isEmpty())
        return false;

    return saveFile(fileName);
}

void MainWindow::about()
{
   QMessageBox::about(this, tr("About Application"),
            tr("The <b>Application</b> example demonstrates how to "
               "write modern GUI applications using Qt, with a menu bar, "
               "toolbars, and a status bar."));
}

void MainWindow::documentWasModified()
{
    setWindowModified(textEdit->document()->isModified());
}

void MainWindow::createActions()
{
    newAct = new QAction(QIcon(":/images/new.png"), tr("&New"), this);
    newAct->setShortcuts(QKeySequence::New);
    newAct->setStatusTip(tr("Create a new file"));
    connect(newAct, SIGNAL(triggered()), this, SLOT(newFile()));

    openAct = new QAction(QIcon(":/images/open.png"), tr("&Open..."), this);
    openAct->setShortcuts(QKeySequence::Open);
    openAct->setStatusTip(tr("Open an existing file"));
    connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

    saveAct = new QAction(QIcon(":/images/save.png"), tr("&Save"), this);
    saveAct->setShortcuts(QKeySequence::Save);
    saveAct->setStatusTip(tr("Save the document to disk"));
    connect(saveAct, SIGNAL(triggered()), this, SLOT(save()));

    saveAsAct = new QAction(tr("Save &As..."), this);
    saveAsAct->setShortcuts(QKeySequence::SaveAs);
    saveAsAct->setStatusTip(tr("Save the document under a new name"));
    connect(saveAsAct, SIGNAL(triggered()), this, SLOT(saveAs()));

    exitAct = new QAction(tr("E&xit"), this);
    exitAct->setShortcuts(QKeySequence::Quit);
    exitAct->setStatusTip(tr("Exit the application"));
    connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));

    cutAct = new QAction(QIcon(":/images/cut.png"), tr("Cu&t"), this);
    cutAct->setShortcuts(QKeySequence::Cut);
    cutAct->setStatusTip(tr("Cut the current selection's contents to the "
                            "clipboard"));
    connect(cutAct, SIGNAL(triggered()), textEdit, SLOT(cut()));

    copyAct = new QAction(QIcon(":/images/copy.png"), tr("&Copy"), this);
    copyAct->setShortcuts(QKeySequence::Copy);
    copyAct->setStatusTip(tr("Copy the current selection's contents to the "
                             "clipboard"));
    connect(copyAct, SIGNAL(triggered()), textEdit, SLOT(copy()));

    pasteAct = new QAction(QIcon(":/images/paste.png"), tr("&Paste"), this);
    pasteAct->setShortcuts(QKeySequence::Paste);
    pasteAct->setStatusTip(tr("Paste the clipboard's contents into the current "
                              "selection"));
    connect(pasteAct, SIGNAL(triggered()), textEdit, SLOT(paste()));

    aboutAct = new QAction(tr("&About"), this);
    aboutAct->setStatusTip(tr("Show the application's About box"));
    connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
    aboutQtAct = new QAction(tr("About &Qt"), this);
    aboutQtAct->setStatusTip(tr("Show the Qt library's About box"));
    connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
    cutAct->setEnabled(false);
    copyAct->setEnabled(false);
    connect(textEdit, SIGNAL(copyAvailable(bool)),
            cutAct, SLOT(setEnabled(bool)));
    connect(textEdit, SIGNAL(copyAvailable(bool)),
            copyAct, SLOT(setEnabled(bool)));
}

void MainWindow::createMenus()//创建菜单
{
    fileMenu = menuBar()->addMenu(tr("&File"));
    fileMenu->addAction(newAct);
    fileMenu->addAction(openAct);
    fileMenu->addAction(saveAct);
    fileMenu->addAction(saveAsAct);
    fileMenu->addSeparator();
    fileMenu->addAction(exitAct);

    editMenu = menuBar()->addMenu(tr("&Edit"));
    editMenu->addAction(cutAct);
    editMenu->addAction(copyAct);
    editMenu->addAction(pasteAct);

    menuBar()->addSeparator();

    helpMenu = menuBar()->addMenu(tr("&Help"));
    helpMenu->addAction(aboutAct);
    helpMenu->addAction(aboutQtAct);
}

void MainWindow::createToolBars()
{
    fileToolBar = addToolBar(tr("File"));
    fileToolBar->addAction(newAct);
    fileToolBar->addAction(openAct);
    fileToolBar->addAction(saveAct);

    editToolBar = addToolBar(tr("Edit"));
    editToolBar->addAction(cutAct);
    editToolBar->addAction(copyAct);
    editToolBar->addAction(pasteAct);
}

void MainWindow::createStatusBar()
{
    statusBar()->showMessage(tr("Ready"));
}

void MainWindow::readSettings()
{
    QSettings settings("Trolltech", "Application Example");
    QPoint pos = settings.value("pos", QPoint(200, 200)).toPoint();
    QSize size = settings.value("size", QSize(400, 400)).toSize();
    resize(size);
    move(pos);
}

void MainWindow::writeSettings()
{
    QSettings settings("Trolltech", "Application Example");
    settings.setValue("pos", pos());
    settings.setValue("size", size());
}

bool MainWindow::maybeSave()
{
    if (textEdit->document()->isModified()) {
        QMessageBox::StandardButton ret;
        ret = QMessageBox::warning(this, tr("Application"),
                     tr("The document has been modified.\n"
                        "Do you want to save your changes?"),
                     QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
        if (ret == QMessageBox::Save)
            return save();
        else if (ret == QMessageBox::Cancel)
            return false;
    }
    return true;
}

void MainWindow::loadFile(const QString &fileName)//载入文件
{
    QFile file(fileName);
    if (!file.open(QFile::ReadOnly | QFile::Text)) {
        QMessageBox::warning(this, tr("Application"),
                             tr("Cannot read file %1:\n%2.")
                             .arg(fileName)
                             .arg(file.errorString()));
        return;
    }

    QTextStream in(&file);
    QApplication::setOverrideCursor(Qt::WaitCursor);
    textEdit->setPlainText(in.readAll());
    QApplication::restoreOverrideCursor();

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File loaded"), 2000);
}

bool MainWindow::saveFile(const QString &fileName)//保存文件
{
    QFile file(fileName);
    if (!file.open(QFile::WriteOnly | QFile::Text)) {
        QMessageBox::warning(this, tr("Application"),
                             tr("Cannot write file %1:\n%2.")
                             .arg(fileName)
                             .arg(file.errorString()));
        return false;
    }

    QTextStream out(&file);
    QApplication::setOverrideCursor(Qt::WaitCursor);
    out << textEdit->toPlainText();
    QApplication::restoreOverrideCursor();

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File saved"), 2000);
    return true;
}

void MainWindow::setCurrentFile(const QString &fileName)
{
    curFile = fileName;
    textEdit->document()->setModified(false);
    setWindowModified(false);

    QString shownName = curFile;
    if (curFile.isEmpty())
        shownName = "untitled.txt";
    setWindowFilePath(shownName);
}

QString MainWindow::strippedName(const QString &fullFileName)//返回文件名
{
    return QFileInfo(fullFileName).fileName();
}

示例4：Syntax Highlighter
这是一个高级例子，用到一个非常靠前的类，继承于QObject的QSyntaxHighlighter。
【1】新建一个空工程，命名为SyntaxHighlighter，添加一个main.cpp文件，添加两个类，一个继承于QMainWindow类，一个继承于QSyntaxHighlighter，分别命名为MainWindow和Highlighter。
【2】添加main.cpp文件代码如下：
#include <QApplication>

#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MainWindow window;
    window.resize(640, 512);
    window.show();
    return app.exec();
}
【3】添加highlighter.h文件代码如下：
public:
    Highlighter(QTextDocument *parent = 0);

protected:
    void highlightBlock(const QString &text);

private:
    struct HighlightingRule
    {
        QRegExp pattern;
        QTextCharFormat format;
    };
    QVector<HighlightingRule> highlightingRules;

    QRegExp commentStartExpression;
    QRegExp commentEndExpression;

    QTextCharFormat keywordFormat;
    QTextCharFormat classFormat;
    QTextCharFormat singleLineCommentFormat;
    QTextCharFormat multiLineCommentFormat;
    QTextCharFormat quotationFormat;
    QTextCharFormat functionFormat;
添加类声明：
#include <QHash>
#include <QTextCharFormat>

QT_BEGIN_NAMESPACE
class QTextDocument;
QT_END_NAMESPACE
【4】添加highlighter.cpp文件中代码如下：
Highlighter::Highlighter(QTextDocument *parent)
    : QSyntaxHighlighter(parent)
{
    HighlightingRule rule;

    keywordFormat.setForeground(Qt::darkBlue);
    keywordFormat.setFontWeight(QFont::Bold);
    QStringList keywordPatterns;
    keywordPatterns << "\\bchar\\b" << "\\bclass\\b" << "\\bconst\\b"
                    << "\\bdouble\\b" << "\\benum\\b" << "\\bexplicit\\b"
                    << "\\bfriend\\b" << "\\binline\\b" << "\\bint\\b"
                    << "\\blong\\b" << "\\bnamespace\\b" << "\\boperator\\b"
                    << "\\bprivate\\b" << "\\bprotected\\b" << "\\bpublic\\b"
                    << "\\bshort\\b" << "\\bsignals\\b" << "\\bsigned\\b"
                    << "\\bslots\\b" << "\\bstatic\\b" << "\\bstruct\\b"
                    << "\\btemplate\\b" << "\\btypedef\\b" << "\\btypename\\b"
                    << "\\bunion\\b" << "\\bunsigned\\b" << "\\bvirtual\\b"
                    << "\\bvoid\\b" << "\\bvolatile\\b";
    foreach (const QString &pattern, keywordPatterns) {
        rule.pattern = QRegExp(pattern);
        rule.format = keywordFormat;
        highlightingRules.append(rule);
    }
    classFormat.setFontWeight(QFont::Bold);
    classFormat.setForeground(Qt::darkMagenta);
    rule.pattern = QRegExp("\\bQ[A-Za-z]+\\b");
    rule.format = classFormat;
    highlightingRules.append(rule);
    singleLineCommentFormat.setForeground(Qt::red);
    rule.pattern = QRegExp("//[^\n]*");
    rule.format = singleLineCommentFormat;
    highlightingRules.append(rule);

    multiLineCommentFormat.setForeground(Qt::red);
    quotationFormat.setForeground(Qt::darkGreen);
    rule.pattern = QRegExp("".*"");
    rule.format = quotationFormat;
    highlightingRules.append(rule);
    functionFormat.setFontItalic(true);
    functionFormat.setForeground(Qt::blue);
    rule.pattern = QRegExp("\\b[A-Za-z0-9_]+(?=\\()");
    rule.format = functionFormat;
    highlightingRules.append(rule);
    commentStartExpression = QRegExp("/\\*");
    commentEndExpression = QRegExp("\\*/");
}

void Highlighter::highlightBlock(const QString &text)
{
    foreach (const HighlightingRule &rule, highlightingRules) {
        QRegExp expression_r(rule.pattern);
        int index = expression.indexIn(text);
        while (index >= 0) {
            int length = expression.matchedLength();
            setFormat(index, length, rule.format);
            index = expression.indexIn(text, index + length);
        }
    }
    setCurrentBlockState(0);
    int startIndex = 0;
    if (previousBlockState() != 1)
        startIndex = commentStartExpression.indexIn(text);

    while (startIndex >= 0) {
        int endIndex = commentEndExpression.indexIn(text, startIndex);
        int commentLength;
        if (endIndex == -1) {
            setCurrentBlockState(1);
            commentLength = text.length() - startIndex;
        } else {
            commentLength = endIndex - startIndex
                            + commentEndExpression.matchedLength();
        }
        setFormat(startIndex, commentLength, multiLineCommentFormat);
        startIndex = commentStartExpression.indexIn(text, startIndex + commentLength);
    }
}
记得添加头文件：
#include <QtGui>
【4】添加mainwindow.h的代码如下：
添加类声明：
#include "highlighter.h"

QT_BEGIN_NAMESPACE
class QTextEdit;
QT_END_NAMESPACE
添加类定义代码如下：
public slots:
    void about();
    void newFile();
    void openFile(const QString &path = QString());

private:
    void setupEditor();
    void setupFileMenu();
    void setupHelpMenu();

    QTextEdit *editor;
    Highlighter *highlighter;
【5】添加mainwindow.cpp文件代码如下：
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    setupFileMenu();
    setupHelpMenu();
    setupEditor();

    setCentralWidget(editor);
    setWindowTitle(tr("Syntax Highlighter"));
}

void MainWindow::about()
{
    QMessageBox::about(this, tr("About Syntax Highlighter"),
                tr("<p>The <b>Syntax Highlighter</b> example shows how " \
                   "to perform simple syntax highlighting by subclassing " \
                   "the QSyntaxHighlighter class and describing " \
                   "highlighting rules using regular expressions.</p>"));
}

void MainWindow::newFile()
{
    editor->clear();
}

void MainWindow::openFile(const QString &path)
{
    QString fileName = path;

    if (fileName.isNull())
        fileName = QFileDialog::getOpenFileName(this,
            tr("Open File"), "", "C++ Files (*.cpp *.h)");

    if (!fileName.isEmpty()) {
        QFile file(fileName);
        if (file.open(QFile::ReadOnly | QFile::Text))
            editor->setPlainText(file.readAll());
    }
}

void MainWindow::setupEditor()
{
    QFont font;
    font.setFamily("Courier");
    font.setFixedPitch(true);
    font.setPointSize(10);

    editor = new QTextEdit;
    editor->setFont(font);

    highlighter = new Highlighter(editor->document());

    QFile file("mainwindow.h");
    if (file.open(QFile::ReadOnly | QFile::Text))
        editor->setPlainText(file.readAll());
}

void MainWindow::setupFileMenu()
{
    QMenu *fileMenu = new QMenu(tr("&File"), this);
    menuBar()->addMenu(fileMenu);

    fileMenu->addAction(tr("&New"), this, SLOT(newFile()),
                        QKeySequence::New);

    fileMenu->addAction(tr("&Open..."), this, SLOT(openFile()),
                        QKeySequence::Open);
                       
    fileMenu->addAction(tr("E&xit"), qApp, SLOT(quit()),
                        QKeySequence::Quit);
}

void MainWindow::setupHelpMenu()
{
    QMenu *helpMenu = new QMenu(tr("&Help"), this);
    menuBar()->addMenu(helpMenu);

    helpMenu->addAction(tr("&About"), this, SLOT(about()));
    helpMenu->addAction(tr("About &Qt"), qApp, SLOT(aboutQt()));
}

示例5：rich text
【1】新建一个空文件，命名为RichText，添加main.cpp文件，添加一个类TextEdit，继承于QMainWindow类。
这里我们添加的资源较多，请先记得添加资源。
【2】添加main.cpp文件中代码如下：
#include "textedit.h"
#include <QApplication>

int main( int argc, char ** argv )
{
    Q_INIT_RESOURCE(textedit);

    QApplication a( argc, argv );
    TextEdit mw;
    mw.resize( 700, 800 );
    mw.show();
    return a.exec();
}
【3】添加textedit.h文件中代码如下：
protected:
    virtual void closeEvent(QCloseEvent *e);

private:
    void setupFileActions();
    void setupEditActions();
    void setupTextActions();
    bool load(const QString &f);
    bool maybeSave();
    void setCurrentFileName(const QString &fileName);

private slots:
    void fileNew();
    void fileOpen();
    bool fileSave();
    bool fileSaveAs();
    void filePrint();
    void filePrintPreview();
    void filePrintPdf();

    void textBold();
    void textUnderline();
    void textItalic();
    void textFamily(const QString &f);
    void textSize(const QString &p);
    void textStyle(int styleIndex);
    void textColor();
    void textAlign(QAction *a);

    void currentCharFormatChanged(const QTextCharFormat &format);
    void cursorPositionChanged();

    void clipboardDataChanged();
    void about();
    void printPreview(QPrinter *);

private:
    void mergeFormatOnWordOrSelection(const QTextCharFormat &format);
    void fontChanged(const QFont &f);
    void colorChanged(const QColor &c);
    void alignmentChanged(Qt::Alignment a);

    QAction *actionSave,
        *actionTextBold,
        *actionTextUnderline,
        *actionTextItalic,
        *actionTextColor,
        *actionAlignLeft,
        *actionAlignCenter,
        *actionAlignRight,
        *actionAlignJustify,
        *actionUndo,
        *actionRedo,
        *actionCut,
        *actionCopy,
        *actionPaste;

    QComboBox *comboStyle;
    QFontComboBox *comboFont;
    QComboBox *comboSize;

    QToolBar *tb;
    QString fileName;
    QTextEdit *textEdit;
添加类声明：
#include <QMap>
#include <QPointer>

QT_FORWARD_DECLARE_CLASS(QAction)
QT_FORWARD_DECLARE_CLASS(QComboBox)
QT_FORWARD_DECLARE_CLASS(QFontComboBox)
QT_FORWARD_DECLARE_CLASS(QTextEdit)
QT_FORWARD_DECLARE_CLASS(QTextCharFormat)
QT_FORWARD_DECLARE_CLASS(QMenu)

【4】添加mainwindow.cpp文件代码如下：
添加类声明：
#include <QAction>
#include <QApplication>
#include <QClipboard>
#include <QColorDialog>
#include <QComboBox>
#include <QFontComboBox>
#include <QFile>
#include <QFileDialog>
#include <QFileInfo>
#include <QFontDatabase>
#include <QMenu>
#include <QMenuBar>
#include <QPrintDialog>
#include <QPrinter>
#include <QTextCodec>
#include <QTextEdit>
#include <QToolBar>
#include <QTextCursor>
#include <QTextDocumentWriter>
#include <QTextList>
#include <QtDebug>
#include <QCloseEvent>
#include <QMessageBox>
#include <QPrintPreviewDialog>
添加全局变量：
const QString rsrcPath = ":/images/mac";
const QString rsrcPath = ":/images/win";
添加构造函数代码：
    setToolButtonStyle(Qt::ToolButtonFollowStyle);
    setupFileActions();
    setupEditActions();
    setupTextActions();

    {
        QMenu *helpMenu = new QMenu(tr("Help"), this);
        menuBar()->addMenu(helpMenu);
        helpMenu->addAction(tr("About"), this, SLOT(about()));
        helpMenu->addAction(tr("About &Qt"), qApp, SLOT(aboutQt()));
    }

    textEdit = new QTextEdit(this);
    connect(textEdit, SIGNAL(currentCharFormatChanged(QTextCharFormat)),
            this, SLOT(currentCharFormatChanged(QTextCharFormat)));
    connect(textEdit, SIGNAL(cursorPositionChanged()),
            this, SLOT(cursorPositionChanged()));

    setCentralWidget(textEdit);
    textEdit->setFocus();
    setCurrentFileName(QString());

    fontChanged(textEdit->font());
    colorChanged(textEdit->textColor());
    alignmentChanged(textEdit->alignment());

    connect(textEdit->document(), SIGNAL(modificationChanged(bool)),
            actionSave, SLOT(setEnabled(bool)));
    connect(textEdit->document(), SIGNAL(modificationChanged(bool)),
            this, SLOT(setWindowModified(bool)));
    connect(textEdit->document(), SIGNAL(undoAvailable(bool)),
            actionUndo, SLOT(setEnabled(bool)));
    connect(textEdit->document(), SIGNAL(redoAvailable(bool)),
            actionRedo, SLOT(setEnabled(bool)));

    setWindowModified(textEdit->document()->isModified());
    actionSave->setEnabled(textEdit->document()->isModified());
    actionUndo->setEnabled(textEdit->document()->isUndoAvailable());
    actionRedo->setEnabled(textEdit->document()->isRedoAvailable());

    connect(actionUndo, SIGNAL(triggered()), textEdit, SLOT(undo()));
    connect(actionRedo, SIGNAL(triggered()), textEdit, SLOT(redo()));

    actionCut->setEnabled(false);
    actionCopy->setEnabled(false);

    connect(actionCut, SIGNAL(triggered()), textEdit, SLOT(cut()));
    connect(actionCopy, SIGNAL(triggered()), textEdit, SLOT(copy()));
    connect(actionPaste, SIGNAL(triggered()), textEdit, SLOT(paste()));

    connect(textEdit, SIGNAL(copyAvailable(bool)), actionCut, SLOT(setEnabled(bool)));
    connect(textEdit, SIGNAL(copyAvailable(bool)), actionCopy, SLOT(setEnabled(bool)));

#ifndef QT_NO_CLIPBOARD
    connect(QApplication::clipboard(), SIGNAL(dataChanged()), this, SLOT(clipboardDataChanged()));
#endif

    QString initialFile = ":/example.html";
    const QStringList args = QCoreApplication::arguments();
    if (args.count() == 2)
        initialFile = args.at(1);

    if (!load(initialFile))
        fileNew();
添加函数代码如下：
void TextEdit::closeEvent(QCloseEvent *e)
{
    if (maybeSave())
        e->accept();
    else
        e->ignore();
}

void TextEdit::setupFileActions()
{
    QToolBar *tb = new QToolBar(this);
    tb->setWindowTitle(tr("File Actions"));
    addToolBar(tb);

    QMenu *menu = new QMenu(tr("&File"), this);
    menuBar()->addMenu(menu);

    QAction *a;

    QIcon newIcon = QIcon::fromTheme("document-new", QIcon(rsrcPath + "/filenew.png"));
    a = new QAction( newIcon, tr("&New"), this);
    a->setPriority(QAction::LowPriority);
    a->setShortcut(QKeySequence::New);
    connect(a, SIGNAL(triggered()), this, SLOT(fileNew()));
    tb->addAction(a);
    menu->addAction(a);

    a = new QAction(QIcon::fromTheme("document-open", QIcon(rsrcPath + "/fileopen.png")),
                    tr("&Open..."), this);
    a->setShortcut(QKeySequence::Open);
    connect(a, SIGNAL(triggered()), this, SLOT(fileOpen()));
    tb->addAction(a);
    menu->addAction(a);

    menu->addSeparator();

    actionSave = a = new QAction(QIcon::fromTheme("document-save", QIcon(rsrcPath + "/filesave.png")),
                                 tr("&Save"), this);
    a->setShortcut(QKeySequence::Save);
    connect(a, SIGNAL(triggered()), this, SLOT(fileSave()));
    a->setEnabled(false);
    tb->addAction(a);
    menu->addAction(a);

    a = new QAction(tr("Save &As..."), this);
    a->setPriority(QAction::LowPriority);
    connect(a, SIGNAL(triggered()), this, SLOT(fileSaveAs()));
    menu->addAction(a);
    menu->addSeparator();

#ifndef QT_NO_PRINTER
    a = new QAction(QIcon::fromTheme("document-print", QIcon(rsrcPath + "/fileprint.png")),
                    tr("&Print..."), this);
    a->setPriority(QAction::LowPriority);   
    a->setShortcut(QKeySequence::Print);
    connect(a, SIGNAL(triggered()), this, SLOT(filePrint()));
    tb->addAction(a);
    menu->addAction(a);

    a = new QAction(QIcon::fromTheme("fileprint", QIcon(rsrcPath + "/fileprint.png")),
                    tr("Print Preview..."), this);
    connect(a, SIGNAL(triggered()), this, SLOT(filePrintPreview()));
    menu->addAction(a);

    a = new QAction(QIcon::fromTheme("exportpdf", QIcon(rsrcPath + "/exportpdf.png")),
    tr("&Export PDF..."), this);
    a->setPriority(QAction::LowPriority);
    a->setShortcut(Qt::CTRL + Qt::Key_D);
    connect(a, SIGNAL(triggered()), this, SLOT(filePrintPdf()));
    tb->addAction(a);
    menu->addAction(a);

    menu->addSeparator();
#endif

    a = new QAction(tr("&Quit"), this);
    a->setShortcut(Qt::CTRL + Qt::Key_Q);
    connect(a, SIGNAL(triggered()), this, SLOT(close()));
    menu->addAction(a);
}

void TextEdit::setupEditActions()
{
    QToolBar *tb = new QToolBar(this);
    tb->setWindowTitle(tr("Edit Actions"));
    addToolBar(tb);
    QMenu *menu = new QMenu(tr("&Edit"), this);
    menuBar()->addMenu(menu);

    QAction *a;
    a = actionUndo = new QAction(QIcon::fromTheme("edit-undo", QIcon(rsrcPath + "/editundo.png")),
                                              tr("&Undo"), this);
    a->setShortcut(QKeySequence::Undo);
    tb->addAction(a);
    menu->addAction(a);
    a = actionRedo = new QAction(QIcon::fromTheme("edit-redo", QIcon(rsrcPath + "/editredo.png")),
                                              tr("&Redo"), this);
    a->setPriority(QAction::LowPriority);
    a->setShortcut(QKeySequence::Redo);
    tb->addAction(a);
    menu->addAction(a);
    menu->addSeparator();
    a = actionCut = new QAction(QIcon::fromTheme("edit-cut", QIcon(rsrcPath + "/editcut.png")),
                                             tr("Cu&t"), this);
    a->setPriority(QAction::LowPriority);
    a->setShortcut(QKeySequence::Cut);
    tb->addAction(a);
    menu->addAction(a);
    a = actionCopy = new QAction(QIcon::fromTheme("edit-copy", QIcon(rsrcPath + "/editcopy.png")),
                                 tr("&Copy"), this);
    a->setPriority(QAction::LowPriority);
    a->setShortcut(QKeySequence::Copy);
    tb->addAction(a);
    menu->addAction(a);
    a = actionPaste = new QAction(QIcon::fromTheme("edit-paste", QIcon(rsrcPath + "/editpaste.png")),
                                  tr("&Paste"), this);
    a->setPriority(QAction::LowPriority);
    a->setShortcut(QKeySequence::Paste);
    tb->addAction(a);
    menu->addAction(a);
#ifndef QT_NO_CLIPBOARD
    actionPaste->setEnabled(!QApplication::clipboard()->text().isEmpty());
#endif
}

void TextEdit::setupTextActions()
{
    QToolBar *tb = new QToolBar(this);
    tb->setWindowTitle(tr("Format Actions"));
    addToolBar(tb);

    QMenu *menu = new QMenu(tr("F&ormat"), this);
    menuBar()->addMenu(menu);

    actionTextBold = new QAction(QIcon::fromTheme("format-text-bold", QIcon(rsrcPath + "/textbold.png")),
                                 tr("&Bold"), this);
    actionTextBold->setShortcut(Qt::CTRL + Qt::Key_B);
    actionTextBold->setPriority(QAction::LowPriority);
 QFont bold;
    bold.setBold(true);
    actionTextBold->setFont(bold);
    connect(actionTextBold, SIGNAL(triggered()), this, SLOT(textBold()));
    tb->addAction(actionTextBold);
    menu->addAction(actionTextBold);
    actionTextBold->setCheckable(true);

    actionTextItalic = new QAction(QIcon::fromTheme("format-text-italic", QIcon(rsrcPath + "/textitalic.png")),
                                   tr("&Italic"), this);
    actionTextItalic->setPriority(QAction::LowPriority);
    actionTextItalic->setShortcut(Qt::CTRL + Qt::Key_I);
    QFont italic;
    italic.setItalic(true);
    actionTextItalic->setFont(italic);
    connect(actionTextItalic, SIGNAL(triggered()), this, SLOT(textItalic()));
    tb->addAction(actionTextItalic);
    menu->addAction(actionTextItalic);
    actionTextItalic->setCheckable(true);

    actionTextUnderline = new QAction(QIcon::fromTheme("format-text-underline", QIcon(rsrcPath + "/textunder.png")),
                                      tr("&Underline"), this);
    actionTextUnderline->setShortcut(Qt::CTRL + Qt::Key_U);
    actionTextUnderline->setPriority(QAction::LowPriority);
    QFont underline;
    underline.setUnderline(true);
    actionTextUnderline->setFont(underline);
    connect(actionTextUnderline, SIGNAL(triggered()), this, SLOT(textUnderline()));
    tb->addAction(actionTextUnderline);
    menu->addAction(actionTextUnderline);
    actionTextUnderline->setCheckable(true);

    menu->addSeparator();

    QActionGroup *grp = new QActionGroup(this);
    connect(grp, SIGNAL(triggered(QAction*)), this, SLOT(textAlign(QAction*)));

    // Make sure the alignLeft  is always left of the alignRight
    if (QApplication::isLeftToRight()) {
        actionAlignLeft = new QAction(QIcon::fromTheme("format-justify-left", QIcon(rsrcPath + "/textleft.png")),
                                      tr("&Left"), grp);
        actionAlignCenter = new QAction(QIcon::fromTheme("format-justify-center", QIcon(rsrcPath + "/textcenter.png")), tr("C&enter"), grp);
        actionAlignRight = new QAction(QIcon::fromTheme("format-justify-right", QIcon(rsrcPath + "/textright.png")), tr("&Right"), grp);
    } else {
        actionAlignRight = new QAction(QIcon::fromTheme("format-justify-right", QIcon(rsrcPath + "/textright.png")), tr("&Right"), grp);
        actionAlignCenter = new QAction(QIcon::fromTheme("format-justify-center", QIcon(rsrcPath + "/textcenter.png")), tr("C&enter"), grp);
        actionAlignLeft = new QAction(QIcon::fromTheme("format-justify-left", QIcon(rsrcPath + "/textleft.png")), tr("&Left"), grp);
    }
    actionAlignJustify = new QAction(QIcon::fromTheme("format-justify-fill", QIcon(rsrcPath + "/textjustify.png")), tr("&Justify"), grp);

    actionAlignLeft->setShortcut(Qt::CTRL + Qt::Key_L);
    actionAlignLeft->setCheckable(true);
    actionAlignLeft->setPriority(QAction::LowPriority);
    actionAlignCenter->setShortcut(Qt::CTRL + Qt::Key_E);
    actionAlignCenter->setCheckable(true);
    actionAlignCenter->setPriority(QAction::LowPriority);
    actionAlignRight->setShortcut(Qt::CTRL + Qt::Key_R);
    actionAlignRight->setCheckable(true);
    actionAlignRight->setPriority(QAction::LowPriority);
    actionAlignJustify->setShortcut(Qt::CTRL + Qt::Key_J);
    actionAlignJustify->setCheckable(true);
    actionAlignJustify->setPriority(QAction::LowPriority);

    tb->addActions(grp->actions());
    menu->addActions(grp->actions());

    menu->addSeparator();

    QPixmap pix(16, 16);
    pix.fill(Qt::black);
    actionTextColor = new QAction(pix, tr("&Color..."), this);
    connect(actionTextColor, SIGNAL(triggered()), this, SLOT(textColor()));
    tb->addAction(actionTextColor);
    menu->addAction(actionTextColor);

    tb = new QToolBar(this);
    tb->setAllowedAreas(Qt::TopToolBarArea | Qt::BottomToolBarArea);
    tb->setWindowTitle(tr("Format Actions"));
    addToolBarBreak(Qt::TopToolBarArea);
    addToolBar(tb);

    comboStyle = new QComboBox(tb);
    tb->addWidget(comboStyle);
    comboStyle->addItem("Standard");
    comboStyle->addItem("Bullet List (Disc)");
    comboStyle->addItem("Bullet List (Circle)");
    comboStyle->addItem("Bullet List (Square)");
    comboStyle->addItem("Ordered List (Decimal)");
    comboStyle->addItem("Ordered List (Alpha lower)");
    comboStyle->addItem("Ordered List (Alpha upper)");
    comboStyle->addItem("Ordered List (Roman lower)");
    comboStyle->addItem("Ordered List (Roman upper)");
    connect(comboStyle, SIGNAL(activated(int)),
            this, SLOT(textStyle(int)));

    comboFont = new QFontComboBox(tb);
    tb->addWidget(comboFont);
    connect(comboFont, SIGNAL(activated(QString)),
            this, SLOT(textFamily(QString)));

    comboSize = new QComboBox(tb);
    comboSize->setObjectName("comboSize");
    tb->addWidget(comboSize);
    comboSize->setEditable(true);

    QFontDatabase db;
    foreach(int size, db.standardSizes())
        comboSize->addItem(QString::number(size));

    connect(comboSize, SIGNAL(activated(QString)),
            this, SLOT(textSize(QString)));
    comboSize->setCurrentIndex(comboSize->findText(QString::number(QApplication::font()
                                                                   .pointSize())));
}

bool TextEdit::load(const QString &f)
{
    if (!QFile::exists(f))
        return false;
    QFile file(f);
    if (!file.open(QFile::ReadOnly))
        return false;

    QByteArray data = file.readAll();
    QTextCodec *codec = Qt::codecForHtml(data);
    QString str = codec->toUnicode(data);
    if (Qt::mightBeRichText(str)) {
        textEdit->setHtml(str);
    } else {
        str = QString::fromLocal8Bit(data);
        textEdit->setPlainText(str);
    }

    setCurrentFileName(f);
    return true;
}

bool TextEdit::maybeSave()
{
    if (!textEdit->document()->isModified())
        return true;
    if (fileName.startsWith(QLatin1String(":/")))
        return true;
    QMessageBox::StandardButton ret;
    ret = QMessageBox::warning(this, tr("Application"),
                               tr("The document has been modified.\n"
                                  "Do you want to save your changes?"),
                               QMessageBox::Save | QMessageBox::Discard
                               | QMessageBox::Cancel);
    if (ret == QMessageBox::Save)
        return fileSave();
    else if (ret == QMessageBox::Cancel)
        return false;
    return true;
}

void TextEdit::setCurrentFileName(const QString &fileName)
{
    this->fileName = fileName;
    textEdit->document()->setModified(false);

    QString shownName;
    if (fileName.isEmpty())
        shownName = "untitled.txt";
    else
        shownName = QFileInfo(fileName).fileName();

    setWindowTitle(tr("%1[*] - %2").arg(shownName).arg(tr("Rich Text")));
    setWindowModified(false);
}

void TextEdit::fileNew()
{
    if (maybeSave()) {
        textEdit->clear();
        setCurrentFileName(QString());
    }
}

void TextEdit::fileOpen()
{
    QString fn = QFileDialog::getOpenFileName(this, tr("Open File..."),
                                              QString(), tr("HTML-Files (*.htm *.html);;All Files (*)"));
    if (!fn.isEmpty())
        load(fn);
}

bool TextEdit::fileSave()
{
    if (fileName.isEmpty())
        return fileSaveAs();

    QTextDocumentWriter writer(fileName);
    bool success = writer.write(textEdit->document());
    if (success)
        textEdit->document()->setModified(false);
    return success;
}

bool TextEdit::fileSaveAs()
{
    QString fn = QFileDialog::getSaveFileName(this, tr("Save as..."),
                                              QString(), tr("ODF files (*.odt);;HTML-Files (*.htm *.html);;All Files (*)"));
    if (fn.isEmpty())
        return false;
    if (! (fn.endsWith(".odt", Qt::CaseInsensitive) || fn.endsWith(".htm", Qt::CaseInsensitive) || fn.endsWith(".html", Qt::CaseInsensitive)) )
        fn += ".odt"; // default
    setCurrentFileName(fn);
    return fileSave();
}

void TextEdit::filePrint()
{
#ifndef QT_NO_PRINTER
    QPrinter printer(QPrinter::HighResolution);
    QPrintDialog *dlg = new QPrintDialog(&printer, this);
    if (textEdit->textCursor().hasSelection())
        dlg->addEnabledOption(QAbstractPrintDialog::PrintSelection);
    dlg->setWindowTitle(tr("Print Document"));
    if (dlg->exec() == QDialog::Accepted) {
        textEdit->print(&printer);
    }
    delete dlg;
#endif
}

void TextEdit::filePrintPreview()
{
#ifndef QT_NO_PRINTER
    QPrinter printer(QPrinter::HighResolution);
    QPrintPreviewDialog preview(&printer, this);
    connect(&preview, SIGNAL(paintRequested(QPrinter*)), SLOT(printPreview(QPrinter*)));
    preview.exec();
#endif
}

void TextEdit::printPreview(QPrinter *printer)
{
#ifdef QT_NO_PRINTER
    Q_UNUSED(printer);
#else
    textEdit->print(printer);
#endif
}

void TextEdit::filePrintPdf()
{
#ifndef QT_NO_PRINTER
//! [0]
    QString fileName = QFileDialog::getSaveFileName(this, "Export PDF",
                                                    QString(), "*.pdf");
    if (!fileName.isEmpty()) {
        if (QFileInfo(fileName).suffix().isEmpty())
            fileName.append(".pdf");
        QPrinter printer(QPrinter::HighResolution);
        printer.setOutputFormat(QPrinter::PdfFormat);
        printer.setOutputFileName(fileName);
        textEdit->document()->print(&printer);
    }
//! [0]
#endif
}

void TextEdit::textBold()
{
    QTextCharFormat fmt;
    fmt.setFontWeight(actionTextBold->isChecked() ? QFont::Bold : QFont::Normal);
    mergeFormatOnWordOrSelection(fmt);
}

void TextEdit::textUnderline()
{
    QTextCharFormat fmt;
    fmt.setFontUnderline(actionTextUnderline->isChecked());
    mergeFormatOnWordOrSelection(fmt);
}

void TextEdit::textItalic()
{
    QTextCharFormat fmt;
    fmt.setFontItalic(actionTextItalic->isChecked());
    mergeFormatOnWordOrSelection(fmt);
}

void TextEdit::textFamily(const QString &f)
{
    QTextCharFormat fmt;
    fmt.setFontFamily(f);
    mergeFormatOnWordOrSelection(fmt);
}

void TextEdit::textSize(const QString &p)
{
    qreal pointSize = p.toFloat();
    if (p.toFloat() > 0) {
        QTextCharFormat fmt;
        fmt.setFontPointSize(pointSize);
        mergeFormatOnWordOrSelection(fmt);
    }
}

void TextEdit::textStyle(int styleIndex)
{
    QTextCursor cursor = textEdit->textCursor();

    if (styleIndex != 0) {
        QTextListFormat::Style style = QTextListFormat::ListDisc;

        switch (styleIndex) {
            default:
            case 1:
                style = QTextListFormat::ListDisc;
                break;
            case 2:
                style = QTextListFormat::ListCircle;
                break;
            case 3:
                style = QTextListFormat::ListSquare;
                break;
            case 4:
                style = QTextListFormat::ListDecimal;
                break;
            case 5:
                style = QTextListFormat::ListLowerAlpha;
                break;
            case 6:
                style = QTextListFormat::ListUpperAlpha;
                break;
            case 7:
                style = QTextListFormat::ListLowerRoman;
                break;
            case 8:
                style = QTextListFormat::ListUpperRoman;
                break;
        }

        cursor.beginEditBlock();

        QTextBlockFormat blockFmt = cursor.blockFormat();

        QTextListFormat listFmt;

        if (cursor.currentList()) {
            listFmt = cursor.currentList()->format();
        } else {
            listFmt.setIndent(blockFmt.indent() + 1);
            blockFmt.setIndent(0);
            cursor.setBlockFormat(blockFmt);
        }

        listFmt.setStyle(style);

        cursor.createList(listFmt);

        cursor.endEditBlock();
    } else {
        // ####
        QTextBlockFormat bfmt;
        bfmt.setObjectIndex(-1);
        cursor.mergeBlockFormat(bfmt);
    }
}

void TextEdit::textColor()
{
    QColor col = QColorDialog::getColor(textEdit->textColor(), this);
    if (!col.isValid())
        return;
    QTextCharFormat fmt;
    fmt.setForeground(col);
    mergeFormatOnWordOrSelection(fmt);
    colorChanged(col);
}

void TextEdit::textAlign(QAction *a)
{
    if (a == actionAlignLeft)
        textEdit->setAlignment(Qt::AlignLeft | Qt::AlignAbsolute);
    else if (a == actionAlignCenter)
        textEdit->setAlignment(Qt::AlignHCenter);
    else if (a == actionAlignRight)
        textEdit->setAlignment(Qt::AlignRight | Qt::AlignAbsolute);
    else if (a == actionAlignJustify)
        textEdit->setAlignment(Qt::AlignJustify);
}

void TextEdit::currentCharFormatChanged(const QTextCharFormat &format)
{
    fontChanged(format.font());
    colorChanged(format.foreground().color());
}

void TextEdit::cursorPositionChanged()
{
    alignmentChanged(textEdit->alignment());
}

void TextEdit::clipboardDataChanged()
{
#ifndef QT_NO_CLIPBOARD
    actionPaste->setEnabled(!QApplication::clipboard()->text().isEmpty());
#endif
}

void TextEdit::about()
{
    QMessageBox::about(this, tr("About"), tr("This example demonstrates Qt's "
        "rich text editing facilities in action, providing an example "
        "document for you to experiment with."));
}

void TextEdit::mergeFormatOnWordOrSelection(const QTextCharFormat &format)
{
    QTextCursor cursor = textEdit->textCursor();
    if (!cursor.hasSelection())
        cursor.select(QTextCursor::WordUnderCursor);
    cursor.mergeCharFormat(format);
    textEdit->mergeCurrentCharFormat(format);
}

void TextEdit::fontChanged(const QFont &f)
{
    comboFont->setCurrentIndex(comboFont->findText(QFontInfo(f).family()));
    comboSize->setCurrentIndex(comboSize->findText(QString::number(f.pointSize())));
    actionTextBold->setChecked(f.bold());
    actionTextItalic->setChecked(f.italic());
    actionTextUnderline->setChecked(f.underline());
}

void TextEdit::colorChanged(const QColor &c)
{
    QPixmap pix(16, 16);
    pix.fill(c);
    actionTextColor->setIcon(pix);
}

void TextEdit::alignmentChanged(Qt::Alignment a)
{
    if (a & Qt::AlignLeft) {
        actionAlignLeft->setChecked(true);
    } else if (a & Qt::AlignHCenter) {
        actionAlignCenter->setChecked(true);
    } else if (a & Qt::AlignRight) {
        actionAlignRight->setChecked(true);
    } else if (a & Qt::AlignJustify) {
        actionAlignJustify->setChecked(true);
    }
}

示例6：Text Object
时间关系，暂无！

二、QSplashScreen类

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