一起看代码来玩玩QT之06Event

.h

#ifndef MYWIDGET_H#define MYWIDGET_H#include <QWidget>#include <QPushButton>#include <QLineEdit>class MyWidget : public QWidget{    Q_OBJECTpublic:    explicit MyWidget(QWidget *parent = 0);    /* widget's event handler (all event) */    bool event(QEvent *);    void mousePressEvent(QMouseEvent *);    void mouseReleaseEvent(QMouseEvent *);    void mouseMoveEvent(QMouseEvent *);    /* 不要用 */   // void mouseDoubleClickEvent(QMouseEvent *);    void keyPressEvent(QKeyEvent *);    void keyReleaseEvent(QKeyEvent *);    void closeEvent(QCloseEvent *); //   void showEvent(QShowEvent *); //   void hideEvent(QHideEvent *);    void paintEvent(QPaintEvent *);    QPushButton* button;    QLineEdit* edit;signals:public slots:    void slotButtonClicked();};#endif // MYWIDGET_H

.cpp

#include "MyWidget.h"#include <QApplication>#include <QEvent>#include <QDebug>#include <QMouseEvent>#include <QKeyEvent>#include <QVBoxLayout>#include <QPainter>MyWidget::MyWidget(QWidget *parent) :    QWidget(parent){//    QVBoxLayout* lay = new QVBoxLayout(this);    QVBoxLayout*lay =new QVBoxLayout();  //  this->setLayout(lay);#if 0    QPushButton* button2;    lay->addWidget(button = new QPushButton("OK", this));    lay->addWidget(button2 = new QPushButton("Button2"));    button->setDefault(true);    // 鼠标不需要按下，mouseMove就能得到调用    this->setMouseTracking(true);    connect(button2, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));    connect(button, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));#endif//    lay->addWidget(edit = new QLineEdit());//    connect(edit, SIGNAL(returnPressed()), this, SLOT(slotButtonClicked()));}void MyWidget::slotButtonClicked(){    QLineEdit* button = (QLineEdit*)sender();    qDebug() << button->text();}/* QApplication先得到->具体应该处理的窗口::event()->event()根据消息类型来调用具体的虚函数 *//* 1）可以重载具体的虚函数，来实现对消息的响应   2）可以重载event函数，用来处理或者截取消息 *//* 截取消息 */bool MyWidget::event(QEvent *ev){    // 鼠标消息被截断   // if(ev->type() == QEvent::MouseButtonPress)     //   return true;    ev->accept();    return QWidget::event(ev);}void MyWidget::closeEvent(QCloseEvent *){    qDebug() << "closeEvent";}void MyWidget::paintEvent(QPaintEvent *){    QPainter p(this);    p.drawLine(QPoint(0, 0), QPoint(100, 100));}void MyWidget::mousePressEvent(QMouseEvent *ev){#if 0    QPoint pt = ev->pos();    qDebug() << pt;    if(ev->button() == Qt::LeftButton)    {    }    if(ev->modifiers() == Qt::ShiftModifier)    {        qDebug() << "shift press";    }#endif    if(ev->button() == Qt::LeftButton)    {        if(ev->modifiers() == Qt::ControlModifier)        {            // handle with Control;            return;        }        // handle2 without control;    }    else    {    }}void MyWidget::mouseReleaseEvent(QMouseEvent *){}void MyWidget::mouseMoveEvent(QMouseEvent *){    static int i=0;    qDebug() << "mouse move"<< i++;}void MyWidget::keyPressEvent(QKeyEvent *ev){    ev->modifiers();    int key = ev->key();    qDebug() << key;    char a = key;    qDebug() << (char)a;}void MyWidget::keyReleaseEvent(QKeyEvent *){}int main(int argc, char* argv[]){    QApplication app(argc, argv);    MyWidget w;    w.show();    return app.exec();}