18.QT-QPlainEdit 信号与槽

QPlainEdit编辑功能

Public Slots

void appendHtml ( const QString & html )
void appendPlainText ( const QString & text )
void centerCursor ()
void clear ()
void copy ()
void cut ()
void insertPlainText ( const QString & text )
void paste ()
void redo ()
void selectAll ()
void setPlainText ( const QString & text )
void undo ()

Signals

void blockCountChanged ( int newBlockCount );
//每当按下回车或者删除回车(更新字符块),则newBlockCount计数,并触发该信号, newBlockCount 默认为1void copyAvailable ( bool yes );
//选择某串文字时,则触发该信号,并设置yes为true,如果取消选择,也会触发该信号,设置 yes为falsevoid cursorPositionChanged ()
////每当光标的位置发生变化时，触发该信号void redoAvailable ( bool available );
//当文本框为空,则会触发该信号,并设置available为false,因为该文本框没有数据,所以无法重做
//当用户向空文本框输入数据时,同样也会触发该信号,设置available为true,表示可以实现重做void selectionChanged ();
//当鼠标点击文本框时,触发该信号void textChanged ();
//每当文档的内容发生变化时,则触发该信号,可以用来判断输入的字符是什么void undoAvailable ( bool available );
//当用户无法撤销时,便会触发该信号,并设置available为false
//当用户修改/写入文本框内容,便会触发该信号,并设置available为true,表示可以撤销

示例代码

Widget.h:

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QPlainTextEdit>
#include <QPushButton>
#include <QDebug>class Widget : public QWidget
{Q_OBJECTQPlainTextEdit edit;QPushButton* Undo;QPushButton*  Redo;QPushButton* Cut;QPushButton* Copy;QPushButton* Paste;QPushButton* all;QPushButton* clear;private slots:void       oncopyAvailable ( bool yes );void       onredoAvailable ( bool available );void       onundoAvailable ( bool available );
public:explicit Widget(QWidget *parent = 0);
};#endif

Widget.c:

#include "Widget.h"Widget::Widget(QWidget *parent) :QWidget(parent),edit(this)
{edit.setGeometry(0,0,280,300);Undo= new QPushButton("重做",this);Redo= new QPushButton("撤销",this);Cut= new QPushButton("剪切",this);Copy= new QPushButton("复制",this);Paste= new QPushButton("拷贝",this);all=  new QPushButton("全选",this);clear=  new QPushButton("删除",this);Undo->setGeometry(290,0,100,30);Redo->setGeometry(290,40,100,30);Cut->setGeometry(290,80,100,30);Copy->setGeometry(290,120,100,30);Paste->setGeometry(290,160,100,30);all->setGeometry(290,200,100,30);clear->setGeometry(290,240,100,30);Undo->setEnabled(false);Redo->setEnabled(false);Cut->setEnabled(false);Copy->setEnabled(false);/*设置按键与文本框槽的关系*/connect(Undo, SIGNAL(clicked()) , &edit ,SLOT(undo()));connect(Redo, SIGNAL(clicked()) ,  &edit ,SLOT(redo()));connect(Cut, SIGNAL(clicked()) ,    &edit ,SLOT(cut()));connect(Copy, SIGNAL(clicked()) ,    &edit ,SLOT(copy()));connect(Paste, SIGNAL(clicked()) ,    &edit ,SLOT(paste()));connect(all, SIGNAL(clicked()) ,  &edit ,SLOT(selectAll()));connect(clear, SIGNAL(clicked()) ,  &edit ,SLOT(clear()));/*设置文本框信号与槽函数的关系*/connect(&edit, SIGNAL(copyAvailable(bool)) , this ,SLOT(oncopyAvailable(bool)));connect(&edit, SIGNAL(redoAvailable(bool)) , this ,SLOT(onredoAvailable(bool)));connect(&edit, SIGNAL(undoAvailable(bool)) , this ,SLOT(onundoAvailable(bool)));connect(&edit, SIGNAL(selectionChanged()) , this ,SLOT(onselectionChanged()));}void    Widget::oncopyAvailable ( bool yes )
{Cut->setEnabled(yes);Copy->setEnabled(yes);
}void    Widget::onredoAvailable( bool available )
{Redo->setEnabled(available);
}void    Widget::onundoAvailable ( bool available )
{Undo->setEnabled(available);
}