qt编程label显示图片，如何在图片上绘制相应图形呢？

1. 先定义一个 QPixmap，在通过QPainter进行绘画。

2. 例子如下：

   QPixmap pixmap(100, 100);
   

   QPainter paint(&pixmap);

   paint.drawLine(); // drawImage 等等各种draw开头的方法。

继承QLabel呗

#include
#include

Label::Label(QWidget *parent) :

QLabel(parent)
{

isRelease = true;

point = QPoint(0, 0);

setScaledContents(true);
}

void Label::mousePressEvent(QMouseEvent *e)
{

point = e->pos();

isRelease = false;

update();
}

void Label::mouseMoveEvent(QMouseEvent *e)
{

point = e->pos();

isRelease = false;

update();
}

void Label::mouseReleaseEvent(QMouseEvent *)
{

isRelease = true;

update();
}

void Label::paintEvent(QPaintEvent *)
{

QPainter painter(this);

painter.drawPixmap(rect(),QPixmap("../123.jpg"));

if(!isRelease)

painter.drawEllipse(point,20,20);
}