做网站外包工作怎么样,杭州网络科技网站建设,学生做兼职哪个网站,呼市浩特网站建设外包公司Qt开发中#xff0c;经常重写event函数和具体的事件处理函数#xff0c;例如mousePressEvent、paintEvent等#xff0c;那么这些具体的事件处理函数是怎样被调用的呢#xff1f;答案是由继承自QObject的类中的event函数来处理事件分发。这里以间接继承自QWidget的派生类MyB…Qt开发中经常重写event函数和具体的事件处理函数例如mousePressEvent、paintEvent等那么这些具体的事件处理函数是怎样被调用的呢答案是由继承自QObject的类中的event函数来处理事件分发。这里以间接继承自QWidget的派生类MyButton举例说明。
MyButton.h
#ifndef MYBUTTON_H
#define MYBUTTON_H#include QPushButtonclass MyButton : public QPushButton
{Q_OBJECT
public:MyButton(QWidget *parent nullptr);~MyButton();protected:bool event(QEvent *e) override;void mousePressEvent(QMouseEvent *event) override;
};#endif // MYBUTTON_HMyButton.cpp
#include MyButton.h
#include QDebug
#include QEvent
#include QMouseEvent
MyButton::MyButton(QWidget *parent) : QPushButton(parent)
{}MyButton::~MyButton()
{}bool MyButton::event(QEvent *e)
{if (e-type() QEvent::MouseButtonPress){qDebug() __FUNCTION__ e-isAccepted();}return QPushButton::event(e);
}void MyButton::mousePressEvent(QMouseEvent *event)
{qDebug() __FUNCTION__ event-isAccepted();
}MainWindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include QMainWindownamespace Ui {
class MainWindow;
}class MainWindow : public QMainWindow
{Q_OBJECTpublic:explicit MainWindow(QWidget *parent nullptr);~MainWindow();protected:bool event(QEvent *e) override;void mousePressEvent(QMouseEvent *event) override;private:Ui::MainWindow *ui;
};#endif // MAINWINDOW_HMainWindow.cpp
#include MainWindow.h
#include ui_MainWindow.h
#include QDebug
#include QEvent
#include QMouseEventMainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{ui-setupUi(this);
}MainWindow::~MainWindow()
{delete ui;
}bool MainWindow::event(QEvent *e)
{if (e-type() QEvent::MouseButtonPress){qDebug() __FUNCTION__ e-isAccepted();}return QMainWindow::event(e);
}void MainWindow::mousePressEvent(QMouseEvent *event)
{qDebug() __FUNCTION__ event-isAccepted();
}运行结果正常
MyButton::event true
MyButton::mousePressEvent true// 若如下修改MyButton::mousePressEvent函数
void MyButton::mousePressEvent(QMouseEvent *event)
{qDebug() __FUNCTION__ event-isAccepted();event-ignore();
}
那么运行结果为该代码同时验证了上一篇文章所说的事件函数的传播
MyButton::event true
MyButton::mousePressEvent true
MainWindow::event true
MainWindow::mousePressEvent true可以看到QPushButton::event(e)函数里最终调用了具体事件处理函数mousePressEvent该函数是在QWidget类的event函数中进行分发的MyButton-QPushButton-QAbstractButton-QWidget层层调用event函数。
补充QWidget中event函数主要负责事件分发
bool QWidget::event(QEvent *event)
{Q_D(QWidget);// ignore mouse and key events when disabledif (!isEnabled()) {switch(event-type()) {case QEvent::TabletPress:case QEvent::TabletRelease:case QEvent::TabletMove:case QEvent::MouseButtonPress:case QEvent::MouseButtonRelease:case QEvent::MouseButtonDblClick:case QEvent::MouseMove:case QEvent::TouchBegin:case QEvent::TouchUpdate:case QEvent::TouchEnd:case QEvent::TouchCancel:case QEvent::ContextMenu:case QEvent::KeyPress:case QEvent::KeyRelease:
#if QT_CONFIG(wheelevent)case QEvent::Wheel:
#endifreturn false;default:break;}}switch (event-type()) {case QEvent::MouseMove:mouseMoveEvent((QMouseEvent*)event);break;case QEvent::MouseButtonPress:mousePressEvent((QMouseEvent*)event);break;case QEvent::MouseButtonRelease:mouseReleaseEvent((QMouseEvent*)event);break;case QEvent::MouseButtonDblClick:mouseDoubleClickEvent((QMouseEvent*)event);break;...default:return QObject::event(event);}return true;
}
