Qt之文本编辑（一）

Qt之文本编辑（一）

文档名称	Qt之文本编辑（一）
创建时间	2012-9-12
修改时间	2012-9-12
创建人	Baifx
简介（收获）	设置字体字号、文本排序对齐

一、设置字体、字号等格式属性。

【应用场景描述】在编辑框中输入一段文字，用鼠标选取文字，修改工具栏上的字体、字号大小、加粗、斜体等属性，选取的文字即发生相应的变化。

【基本概念】在编写包含格式设置的文本编辑程序时，经常用到的Qt类有：QTextEdit、QTextDocument、QTextCharFormat、QTextCursor、QTextBlock、QTextList、QTextFrame、QTextTable、QTextBlockFormat、QTextListFormat、QTextFrameFormat、QTextTableFormat等。刚看到如此多的相关类可能会感到有些混乱，但只要弄清了它们之间的关系，运用起来就会非常方便，Qt已经为用户完成了几乎所有与编辑有关的具体工作，我们所要做的就是运用合适的类，调用合适的函数接口。

首先，任何一个文本编辑器的程序都要用到QTextEdit作为输入文本的容器，在它里面输入的可编辑文本由QTextDocument作为载体，而QTextBlock、QTextList、QTextFrame等则用来表示QTextDocument的元素，也可理解为QTextDocument的不同表现形式，可能为字符串、段落、列表、表格或是图片等。每种元素都有自己的格式，这些格式则用QTextCharFormat、QTextBlockFormat、QTextListFormat、QTextFrameFormat等类来描述与实现。例如，QTextBlockFormat类对应于QTextBlock类，QTextBlock类用于表示一块文本，一般可以理解为一个段落，但并不只指段落，QTextBlockFormat类则用于表示这一块文本的格式，如缩进值、与四边的边距等。各类之间的划分与关系可用下图进行描述：





从上图可知，QTextCursor类是一个非常重要也经常会用到的类，它用于表示编辑文本中的光标。这个类提供了对QTextDocument文档的修改接口，所有对文档格式的修改，说到底都与光标有关，如改变字符的格式，指的是改变光标处字符的格式；改变段落的格式，指的是改变光标所在段落的格式，因此，QTextCursor类在文档编辑类程序中有着重要的作用，所有对QTextDocument的修改能够通过QTextCursor类实现。

【继承关系】





【实例】





fontset.h代码：

class FontSet : public QMainWindow

{

Q_OBJECT

public:

FontSet(QWidget *parent = 0, Qt::WFlags flags = 0);

~FontSet();

protected slots:

void slotFont( QString f );

void slotSize( QString num );

void slotBold();

void slotItalic();

void slotUnder();

void slotColor();

void slotCurrentFormatChanged( const QTextCharFormat & fmt );

private:

void mergeFormat( QTextCharFormat fmt );

private:

QLabel * pLabel1;

QLabel * pLabel2;

QFontComboBox * pFontBox;

QComboBox * pSizeBox;

QToolButton * pBoldBtn;

QToolButton * pItalicBtn;

QToolButton * pUnderBtn;

QToolButton * pColorBtn;

QTextEdit * pText;

};

fontset.cpp代码：

FontSet::FontSet(QWidget *parent, Qt::WFlags flags)

: QMainWindow(parent, flags)

{

setWindowTitle( tr( "Font" ) );

pText = new QTextEdit( tr( "ajglkajdkgnakjfdsklaj" ), this );

setCentralWidget( pText );

QToolBar * pToolBar = addToolBar( "Font" );

//字体

pLabel1 = new QLabel( tr( "ZiTi:" ) );

pFontBox = new QFontComboBox();

pFontBox->setFontFilters( QFontComboBox::ScalableFonts );

pToolBar->addWidget( pLabel1 );

pToolBar->addWidget( pFontBox );

//字号

pLabel2 = new QLabel( tr( "ZiHao:" ) );

pSizeBox = new QComboBox();

pToolBar->addWidget( pLabel2 );

pToolBar->addWidget( pSizeBox );

QFontDatabase db;

foreach( int nSize, db.standardSizes() )

pSizeBox->addItem( QString::number( nSize ) );

pToolBar->addSeparator();

//加粗、斜体、下划线、颜色

pBoldBtn = new QToolButton();

pBoldBtn->setIcon( QIcon( ".//Resources//bold.png" ) );

pBoldBtn->setCheckable( true );

pToolBar->addWidget( pBoldBtn );

pItalicBtn = new QToolButton();

pItalicBtn->setIcon( QIcon( ".//Resources//italic.png" ) );

pItalicBtn->setCheckable( true );

pToolBar->addWidget( pItalicBtn );

pUnderBtn = new QToolButton();

pUnderBtn->setIcon( QIcon( ".//Resources//underline.png" ) );

pUnderBtn->setCheckable( true );

pToolBar->addWidget( pUnderBtn );

pToolBar->addSeparator();

pColorBtn = new QToolButton();

pColorBtn->setIcon( QIcon( ".//Resources//color.png" ) );

pToolBar->addWidget( pColorBtn );

//连接信号与槽函数

connect( pFontBox, SIGNAL( activated( QString ) ), this, SLOT( slotFont( QString ) ) );

connect( pSizeBox, SIGNAL( activated( QString ) ), this, SLOT( slotSize( QString ) ) );

connect( pBoldBtn, SIGNAL( clicked() ), this, SLOT( slotBold() ) );

connect( pItalicBtn, SIGNAL( clicked() ), this, SLOT( slotItalic() ) );

connect( pUnderBtn, SIGNAL( clicked() ), this, SLOT( slotUnder() ) );

connect( pColorBtn, SIGNAL( clicked() ), this, SLOT( slotColor() ) );

connect( pText, SIGNAL( currentCharFormatChanged( const QTextCharFormat & ) ), this, SLOT( slotCurrentFormatChanged( const QTextCharFormat& ) ) );

}

FontSet::~FontSet()

{

}

void FontSet::slotFont( QString f )

{

QTextCharFormat fmt;

fmt.setFontFamily( f );

mergeFormat( fmt );

}

void FontSet::slotSize( QString num )

{

QTextCharFormat fmt;

fmt.setFontPointSize( num.toFloat() );

mergeFormat( fmt );

}

void FontSet::slotBold()

{

QTextCharFormat fmt;

fmt.setFontWeight( pBoldBtn->isChecked() ? QFont::Bold : QFont::Normal );

mergeFormat( fmt );

//pText->mergeCurrentCharFormat( fmt );

}

void FontSet::slotItalic()

{

QTextCharFormat fmt;

fmt.setFontItalic( pItalicBtn->isChecked() );

mergeFormat( fmt );

}

void FontSet::slotUnder()

{

QTextCharFormat fmt;

fmt.setFontUnderline( pUnderBtn->isChecked() );

mergeFormat( fmt );

}

void FontSet::slotColor()

{

QColor color = QColorDialog::getColor( Qt::red, this );

if ( color.isValid() )

{

QTextCharFormat fmt;

fmt.setForeground( color );

mergeFormat( fmt );

}

}

/*当光标所在处的字符格式发生变化时调用，函数根据新的字符格式把工具栏上的各个格式控件的显示更新*/

void FontSet::slotCurrentFormatChanged( const QTextCharFormat & fmt )

{

pFontBox->setCurrentIndex( pFontBox->findText( fmt.fontFamily() ) );

pSizeBox->setCurrentIndex( pSizeBox->findText( QString::number( fmt.fontPointSize() ) ) );

pBoldBtn->setChecked( fmt.font().bold() );

pItalicBtn->setChecked( fmt.fontItalic() );

pUnderBtn->setChecked( fmt.fontUnderline() );

}

/*设置光标的选区，使格式作用于选区内的字符，若没有选区则作用于光标所在处的字符*/

void FontSet::mergeFormat( QTextCharFormat fmt )

{

QTextCursor cursor = pText->textCursor();

if ( !cursor.hasSelection() )

cursor.select( QTextCursor::WordUnderCursor );

cursor.mergeCharFormat( fmt );

pText->mergeCurrentCharFormat( fmt );

}

二、设置文本排序及对齐

QTextListFormat主要用于描述文本排序的格式，它主要包括两个基本属性，一个味QTextListFormat::style，表示文本采用哪种排序方式；另一种为QTextListFormat::indent，表示排序后的缩进值。因此，要实现文本排序的功能只需设置好QTextListFormat的这两个属性，并把整个格式通过QTextCursor类应用到文本中即可。





【实例】





listalign.h代码：

class listAlign : public QMainWindow

{

Q_OBJECT

public:

listAlign(QWidget *parent = 0, Qt::WFlags flags = 0);

~listAlign();

protected slots:

void slotAlignment( QAction * );

void slotList( int );

void slotCursorPositionChanged();

private:

QTextEdit * pText;

QLabel * pLabel;

QComboBox * pListBox;

QAction * pLeftAction;

QAction * pRightAction;

QAction * pCenterAction;

QAction * pJustifyAction;

QAction * pRedoAction;

QAction * pUndoAction;

};

listalign.cpp代码：

listAlign::listAlign(QWidget *parent, Qt::WFlags flags)

: QMainWindow(parent, flags)

{

QFont f( "ZYSong18030", 12 );

setFont( f );

setWindowTitle( tr( "List&Alignment" ) );

QToolBar * pToolBar = addToolBar( "List" );

pLabel = new QLabel( tr( "List:" ) );

pListBox = new QComboBox( pToolBar );

pListBox->addItem( tr( "Standard" ) );

pListBox->addItem( tr( "Bullet List (Disc)" ) );

pListBox->addItem( tr( "Bullet List (Circle)" ) );

pListBox->addItem( tr( "Bullet List (Square)" ) );

pListBox->addItem( tr( "Ordered List (Decimal)" ) );

pListBox->addItem( tr( "Ordered List (Alpha lower)" ) );

pListBox->addItem( tr( "Ordered List (Alpha upper)" ) );

pToolBar->addWidget( pLabel );

pToolBar->addWidget( pListBox );

pToolBar->addSeparator();

QActionGroup * pActGrp = new QActionGroup( this );

pLeftAction = new QAction( QIcon( ".//Resources//left.png" ), tr( "left" ), pActGrp );

pLeftAction->setCheckable( true );

pCenterAction = new QAction( QIcon( ".//Resources//center.png" ), tr( "center" ), pActGrp );

pCenterAction->setCheckable( true );

pJustifyAction = new QAction( QIcon( ".//Resources//justify.png" ), tr( "justify" ), pActGrp );

pJustifyAction->setCheckable( true );

pRightAction = new QAction( QIcon( ".//Resources//right.png" ), tr( "right" ), pActGrp );

pRightAction->setCheckable( true );

pToolBar->addActions( pActGrp->actions() );

QToolBar * pEditBar = addToolBar( "Edit" );

pUndoAction = new QAction( QIcon( ".//Resources//undo.png" ), tr( "undo" ), this );

pEditBar->addAction( pUndoAction );

pRedoAction = new QAction( QIcon( ".//Resources//redo.png" ), tr( "redo" ), this );

pEditBar->addAction( pRedoAction );

pText = new QTextEdit( this );

pText->setFocus();

setCentralWidget( pText );

connect( pListBox, SIGNAL( activated( int) ), this, SLOT( slotList( int ) ) );

connect( pActGrp, SIGNAL( triggered( QAction * ) ), this, SLOT( slotAlignment( QAction * ) ) );

connect( pRedoAction, SIGNAL( triggered() ), pText, SLOT( redo() ) );

connect( pUndoAction, SIGNAL( triggered() ), pText, SLOT( undo() ) );

connect( pText->document(), SIGNAL( redoAvailable( bool ) ), pRedoAction, SLOT( setEnabled( bool ) ) );

connect( pText->document(), SIGNAL( undoAvailable( bool ) ), pUndoAction, SLOT( setEnabled( bool ) ) );

connect( pText, SIGNAL( cursorPositionChanged() ), this, SLOT( slotCursorPositionChanged() ) );

}

listAlign::~listAlign()

{

}

void listAlign::slotAlignment( QAction * act )

{

if ( act == pLeftAction )

pText->setAlignment( Qt::AlignLeft );

if ( act == pCenterAction )

pText->setAlignment( Qt::AlignCenter );

if ( act == pJustifyAction )

pText->setAlignment( Qt::AlignJustify );

if ( act == pRightAction )

pText->setAlignment( Qt::AlignRight );

}

void listAlign::slotList( int index )

{

QTextCursor cursor = pText->textCursor();

if ( index != 0 )

{

QTextListFormat::Style style = QTextListFormat::ListDisc;

switch ( index )

{

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;

}

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 listAlign::slotCursorPositionChanged()

{

if ( pText->alignment() == Qt::AlignLeft)

pLeftAction->setChecked(true);

if (pText->alignment() == Qt::AlignCenter)

pCenterAction->setChecked(true);

if (pText->alignment() == Qt::AlignJustify)

pJustifyAction->setChecked(true);

if (pText->alignment() == Qt::AlignRight)

pRightAction->setChecked(true);

}