一起看代码来玩玩QT之06EventFilter (事件过滤)

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我是靠谱客的博主清爽芹菜，最近开发中收集的这篇文章主要介绍一起看代码来玩玩QT之06EventFilter (事件过滤)，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

filter : 过滤

notify: 通知

MyApplication.h

#ifndef MYAPPLICATION_H
#define MYAPPLICATION_H

#include <QApplication>

class MyApplication : public QApplication
{
    Q_OBJECT
public:

    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_OBJECT
public:
    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();
}