一起看代码来玩玩QT之06EventFilter (事件过滤)

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filter : 过滤

notify: 通知

MyApplication.h

#ifndef MYAPPLICATION_H#define MYAPPLICATION_H#include <QApplication>class MyApplication : public QApplication{    Q_OBJECTpublic:    MyApplication(int argc, char*argv[]):QApplication(argc, argv)    {}    bool notify(QObject *, QEvent *);signals:public slots:};#endif // MYAPPLICATION_H

MyApplication.cpp

#include "MyApplication.h"#include <QEvent>#include <QDebug>bool MyApplication::notify(QObject *o, QEvent *e){    if(this->topLevelWidgets().count()>0)    {        QWidget* mainWnd = this->topLevelWidgets().at(0);        if(o==(QObject*)mainWnd && e->type() == QEvent::MouseButtonPress)        {            // do ...            qDebug() << "mainwnd is clicked";        }    }    return QApplication::notify(o, e);}

MyWidget.h

#ifndef MYWIDGET_H#define MYWIDGET_H#include <QWidget>#include <QPushButton>class MyWidget : public QWidget{    Q_OBJECTpublic:    explicit MyWidget(QWidget *parent = 0);    QPushButton* _button;    bool eventFilter(QObject *, QEvent *);    bool event(QEvent *);signals:public slots:};#endif // MYWIDGET_H

MyWidget.cpp

#include "MyWidget.h"#include <QPushButton>#include <QEvent>#include "MyApplication.h"#include <QDebug>#include <QApplication>MyWidget::MyWidget(QWidget *parent) :    QWidget(parent){    QPushButton* button;    button = new QPushButton("This button", this);    connect(button, SIGNAL(clicked()), this, SLOT(close()));    _button = button;    /* button给自己安装了一个消息过滤器，那么经过button的消息，都先要调用它的过滤器的eventFilter函数 */    button->installEventFilter(this);}bool MyWidget::eventFilter(QObject *o, QEvent *e){#if 0    if(o == (QObject*)_button &&(                e->type() == QEvent::MouseButtonRelease ||                e->type() == QEvent::MouseButtonDblClick ||                e->type() == QEvent::MouseButtonPress))    {        return true;    }#endif    return QWidget::eventFilter(o, e);}bool MyWidget::event(QEvent *e){    if(e->type() == QEvent::User)    {        qDebug() << "User event is comming";    }    return QWidget::event(e);}int main(int argc, char* argv[]){    MyApplication app(argc, argv);    MyWidget w;    w.show();    // 发送一个Event给MyWidget    qDebug() << "begin send";    app.postEvent(&w, new QEvent(QEvent::User));    qDebug() << "end send";   // app.sendEvent(&w, )    return app.exec();}

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