QMouseEvent下可以被重写的虚函数:

1.void mousePressEvent(QMouseEvent *event); //鼠标键被按下的事件.

2.void mouseReleaseEvent(QMouseEvent *event); //鼠标键被放开的事件.

3.void mouseMoveEvent(QMouseEvent *event); //按住鼠标键移动的事件.

4.void mouseDoubleClickEvent(QMouseEvent *event); //鼠标键被双击的事件.

QMouseEvent类中的重要函数:

1.QPoint pos(); //返回鼠标相对于父部件的坐标.

2.QPoint globalPos(); //返回鼠标的全局坐标.

3.QMouseButton button(); //返回鼠标被点击的键.

“c.cpp”下的代码:#include "c.h"c::c(QWidget *parent)

: QMainWindow(parent)

{

ui.setupUi(this);

}

c::~c()

{

}void c::mouseMoveEvent(QMouseEvent *event)

{    //保存鼠标移动的时候的尾坐标.

end = event->pos();    //用来重绘更新.可以理解为调用paintEvent函数，但不一定是立即调用的.在此程序中可以理解为:马上更新窗口上显示的图像.

update();

}void c::paintEvent(QPaintEvent *event)

{    //画一个矩形.

QPainter painter(this);

painter.setPen(Qt::red);

QRect temp(start, end);

painter.setBrush(Qt::green);

painter.drawRect(temp);

}void c::mouseReleaseEvent(QMouseEvent *event)

{    //当左键释放后，保存尾坐标.

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

{        this->end = event->pos();

update();

}

}void c::mousePressEvent(QMouseEvent *event)

{    //当左键被按下时，保存首坐标.并更新重绘.

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

{        //点击的时候定下初始位置.

this->start = event->pos();

}

}123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051

“c.h”的代码:#ifndef C_H#define C_H#include #include "ui_c.h"#include #include #include #include #include #include class c : public QMainWindow

{

Q_OBJECTpublic:    c(QWidget *parent = 0);

~c();protected:    void mouseMoveEvent(QMouseEvent *event);    void mouseReleaseEvent(QMouseEvent *event);    void mousePressEvent(QMouseEvent *event);    void paintEvent(QPaintEvent *event);private:

Ui::cClass ui;

QPoint start;

QPoint end;

};#endif // C_H1234567891011121314151617181920212223242526272829303132

最后是”main.cpp”下的代码:#include "c.h"#include int main(int argc, char *argv[])

{

QApplication a(argc, argv);

c w;

w.show();    return a.exec();

}