不知道自己是码农的二流码农！
分类： C/C++
2012-09-12 18:29:10
Qt之文本编辑（一）
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文档名称 |
Qt之文本编辑（一） |
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创建时间 |
2012-9-12 |
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修改时间 |
2012-9-12 |
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创建人 |
Baifx |
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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);
}
