19.QT-事件发送函数sendEvent()、postEvent()

bool QApplication::sendEvent ( QObject * receiver, QEvent * event ) ;
              // receiver:接收对象, event :要发送的event类型(比如:鼠标双击)
              //当有事件发送,将会调用receiver对象里的event()成员函数进行事件处理

void QApplication::postEvent ( QObject * receiver, QEvent * event ); 

#ifndef WIDGET_H

#define WIDGET_H

#include <QWidget>

#include <QtGui>

class Widget : public QWidget

{

    Q_OBJECT

private :

    QTextEdit edit;

    QPushButton bt;

 

private slots:

   void  onPushButton();

public:

    explicit Widget();

};

#endif // WIDGET_H

#include "widget.h"

Widget::Widget() :  edit(this),bt("Delete",this)
{
    edit.setGeometry(0,0,300,200);
    bt.setGeometry(310,20,48,32);
    connect(&bt, SIGNAL(clicked()), this, SLOT(onPushButton()));
}

void Widget::onPushButton()
{
     int  key = Qt::Key_Delete ;

     QKeyEvent EventPress(QEvent::KeyPress,key,Qt::NoModifier); 
     QApplication::sendEvent(&edit,&EventPress);   //发送键盘按下事件

     QKeyEvent EventRelease(QEvent::KeyRelease,key,Qt::NoModifier);
     QApplication::sendEvent(&edit,&EventRelease); //发送键盘松开事件
}

class StringEvent : public QEvent
{
public：
       static const Type = static_cast<Type>(QEvent::User+0x10);
       explicit QStringEvent();
      //... ...
}

QStringEvent::QStringEvent() :
    QEvent(TYPE)     //注册TYPE值
{
        //... ...
}

class QStringEvent : public QEvent
{
private:
    QString mstr;

public:
    const static Type TYPE = static_cast<Type>(QEvent::User+0x10);
    explicit QStringEvent(QString s);
    QString str();
};

QStringEvent::QStringEvent(QString s) :
    QEvent(TYPE)
{
    mstr = s;
}

QString QStringEvent::str()
{
    return mstr;
}

class Widget : public QWidget
{
private :
    QLabel  label;
    bool event( QEvent * e);
    bool eventFilter(QObject *obj, QEvent *event);

public:
    explicit Widget();
};


Widget::Widget() :  label(this)
{
    label.installEventFilter(this);
}

bool Widget::event( QEvent * e)
{
    if(e->type() == QEvent::MouseButtonPress)      
    {
        QMouseEvent *me = dynamic_cast<QMouseEvent* >(e);if(me->button() == Qt::LeftButton)         
        {
            QStringEvent event( QString("X坐标: %1  Y坐标: %2").arg(me->x()).arg(me->y()) );
            QApplication::sendEvent(&label,&event);         //发送自定义事件
        }
    }

   return QWidget::event(e);
}

bool Widget::eventFilter(QObject *obj, QEvent *event)
{
    QLabel *t = dynamic_cast<QLabel* >(obj);

    if(t && event->type()== QStringEvent::TYPE )
    {
        QStringEvent *str = dynamic_cast<QStringEvent* >(event);
        t->setText(str->str());
        t->adjustSize();
        return true;
    }

    return QWidget::eventFilter(obj,event);
}