什么是qt鼠标事件

2017-05-05

大家了解qt鼠标事件吗?不知道的话跟着小编一起来学习了解qt鼠标事件吧。

qt鼠标事件大全

1、QMouseEvent中的坐标

QMouseEvent中保存了两个坐标,一个是全局坐标,当然另外一个是局部坐标。

全局坐标(globalPos())即是桌面屏幕坐标(screen coordinates),这个跟windows下的调用getCursorPos函数得到的结果一致。

局部坐标(pos())即是相对当前active widget的坐标,左上角坐标为(0, 0)。

补充一个公式:

this->mapFromGlobal(this->cursor().pos()) = event.pos()

2、鼠标跟踪

在qt中,鼠标跟踪对应函数mouseMoveEvent。但是,默认情况下他并不能如期象你想象的那样响应鼠标的移动。此时,你只需在合适的位置调用一下函数setMouseTracking(true)即可。

If mouse tracking is switched off, mouse move events only occur if a mouse button is pressed while the mouse is being moved.

If mouse tracking is switched on, mouse move events occur even if no mouse button is pressed.

默认情况下,mouseMoveEvent响应你按下鼠标的某个键(拖动,但不局限于左键拖动)的鼠标移动。

3、鼠标左键拖动和左键点击的判断

鼠标左键点击很容易判断,一般就是在重写mousePressEvent函数,示例如下:

void XXXWidget::mousePressEvent(QMouseEvent *event)

{

if(event->button() == Qt::LeftButton)

{

// todo ...

}

}

左键拖动的判断一般放在mouseMoveEvent函数中,但是你不能向上例一样来判断,因为该函数的event参数总是返回Qt::NoButton。你可以这样做:

void XXXWidget::mouseMoveEvent(QMouseEvent *event)

{

if(event->buttons() & Qt::LeftButton)

{

// todo ...

}

}

参考教材实例,增加了注释和新功能,方便大家交流学习

mouseevent.cpp

#include "mouseevent.h"

MouseEvent::MouseEvent( ):QMainWindow()

{

setWindowTitle(tr("Get Mouse Event"));

setCursor(Qt::CrossCursor); //设置鼠标为十字星

labelStatus = new QLabel();

labelStatus->setMinimumSize(500,20);

labelStatus->setFrameShape(QFrame::WinPanel);//设置标签形状

labelStatus->setFrameShadow(QFrame::Sunken); //设置标签阴影;

labelStatus->setText(tr("Mouse Position:"));

labelStatus -> setFixedWidth (100);

labelMousePos = new QLabel();

labelMousePos->setText(tr(""));

labelMousePos -> setFixedWidth (100);

statusBar()->addPermanentWidget(labelStatus);//给状态栏添加永久的部件

statusBar()->addPermanentWidget(labelMousePos);

this->setMouseTracking ( true);//自动跟踪鼠标(默认情况下,mouseMoveEvent响应你按下鼠标的某个键的鼠标移动。)

}

MouseEvent::~MouseEvent(){

}

void MouseEvent::mouseMoveEvent ( QMouseEvent * e )//鼠标移动事件响应

{

//1.获取局部鼠标位置

labelMousePos ->setText("("+QString::number(e->x())+","+QString::number(e->y())+")");

//2.获取全局鼠标位置

QPoint coursePoint;

coursePoint = QCursor::pos();//获取当前光标的位置

labelMousePos ->setText("("+QString::number(coursePoint.x())+","+QString::number(coursePoint.y())+")");

}

void MouseEvent::mousePressEvent ( QMouseEvent * e )//鼠标单击事件响应

{

QString str="("+QString::number(e->x())+","+QString::number(e->y())+")";

if(e->button()==Qt::LeftButton){

statusBar()->showMessage (tr("Mouse Left Button Pressed:")+str);//显示临时信息

}

else if(e->button()==Qt::RightButton){

statusBar()->showMessage (tr("Mouse Right Button Pressed:")+str);

}

else if(e->button()==Qt::MidButton){

statusBar()->showMessage (tr("Mouse Middle Button Pressed:")+str);

}

}

void MouseEvent::mouseDoubleClickEvent( QMouseEvent * e )//鼠标双击事件响应

{ QString str="("+QString::number(e->x())+","+QString::number(e->y())+")";

if(e->button()==Qt::LeftButton){

statusBar()->showMessage (tr("Mouse Left Button Double Clicked:")+str);

}

else if(e->button()==Qt::RightButton){

statusBar()->showMessage (tr("Mouse Right Button Double Clicked:")+str);

}

else if(e->button()==Qt::MidButton){

statusBar()->showMessage (tr("Mouse Middle Button Double Clicked:")+str);

}

}

void MouseEvent::mouseReleaseEvent ( QMouseEvent * e )//鼠标松开事件响应

{

QString str="("+QString::number(e->x())+","+QString::number(e->y())+")";

statusBar()->showMessage (tr("Mouser Released:")+str,3000);

}

mouseevent.h

#ifndef MOUSEEVENT_H

#define MOUSEEVENT_H

#include <QtGui>

class MouseEvent : public QMainWindow

{ Q_OBJECT

public:MouseEvent();

~MouseEvent();

private:

QLabel *labelStatus;

QLabel *labelMousePos;

protected :

void mouseMoveEvent ( QMouseEvent * e );

void mousePressEvent ( QMouseEvent * e );

void mouseReleaseEvent ( QMouseEvent * e );

void mouseDoubleClickEvent( QMouseEvent * e );

};

#endif

main.cpp

#include<QtGui/QApplication>

#include "mouseevent.h"

int main(int argc, char *argv[])

{

QApplication app(argc, argv);

MouseEvent w;w.show();

return app.exec();

}

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