Qt-- event mechanism (c)

Increase the number of small features in the main window of the Widget

1, click the left button to display the "haha" label in the upper left corner, right-click to display the "lala"

In widget.h added:

1 #include <QMouseEvent>
2 protected:
3     void mousePressEvent(QMouseEvent *);

In widget.cpp added:

1 void Widget::mousePressEvent(QMouseEvent *ev){
2     if(ev->button()==Qt::LeftButton){
3         ui->label->setText("haha");
4     }else if(ev->button()==Qt::RightButton){
5         ui->label->setText("lala");
6     }
7 }

2, the coordinates of the mouse click point is displayed in the label

 Only minor changes to the Widget :: mousePressEvent ():

1 void Widget::mousePressEvent(QMouseEvent *ev){
2     QPoint point=ev->pos();
3     if(ev->button()==Qt::LeftButton){
4         ui->label->setText(QString::asprintf("%d",point.x()));
5     }else if(ev->button()==Qt::RightButton){
6         ui->label->setText(QString::asprintf("%d",point.y()));
7     }
8 }

3, real-time display coordinates of the mouse position

Modify widget.cpp:

 1 Widget::Widget(QWidget *parent) :
 2     QWidget(parent),
 3     ui(new Ui::Widget)
 4 {
 5     ui->setupUi(this);
 6     this->setMouseTracking(true);
 7 }
 8 
 9 Widget::~Widget()
10 {
11     delete ui;
12 }
13 
14 void Widget::mouseMoveEvent(QMouseEvent *ev){
15     QPoint point=ev->pos();
16     ui->label->setText(QString::asprintf("坐标：%d %d",point.x(),point.y()));
17 }

• Line 6 is set to real-time tracking mouse, if not, we should hold the mouse while moving coordinate changes have
• Do not forget to declare mouseMoveEvent in widget.h in ()