setMask的使用：遮罩

实现不规则窗体，鼠标右键窗体关闭窗口，左键长按可以拖动窗口

widget.h文件添加：

protected:void paintEvent(QPaintEvent *event);//画家事件void mousePressEvent(QMouseEvent *event);//鼠标点击事件void mouseMoveEvent(QMouseEvent *event);//鼠标移动事件QPoint point;//点位

widget.cpp中实现：

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter(this);QPixmap pixmap(":/image/456.png",0,Qt::AvoidDither|Qt::ThresholdDither|Qt::ThresholdAlphaDither);this->setMask(pixmap.mask());//需要添加头文件#include
}
void Widget::mousePressEvent(QMouseEvent *event)
{if(event->button()==Qt::RightButton)//右键点击  关闭窗口{close();}point=event->globalPos()-frameGeometry().topLeft();//获取差值event->accept();
}
void Widget::mouseMoveEvent(QMouseEvent *event)
{if(event->buttons()&Qt::LeftButton){move(event->globalPos()-point);event->accept();}}

QPixmap绘制图像：

QPixmap的底色默认为黑色，可以自己使用fill（）添加底色。

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter;QPixmap pixmap(200,200);//设置图片大小painter.begin(&pixmap);//给pixmap绘制painter.setPen(Qt::red);painter.setBrush(Qt::cyan);painter.drawRect(0,0,100,100);painter.drawEllipse(100,100,100,100);painter.end();painter.begin(this);painter.drawPixmap(100,100,pixmap);}

 QPicture

QPicture 类是一种绘制设备，用于记录和重播QPainter命令。QPicture与分辨率无关，即QPicture可以显示在不同的设备上

 QPicture绘制图形：

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter;QPicture picture;painter.begin(&picture);painter.drawRect(0,0,100,100);painter.drawEllipse(100,100,100,100);painter.end();painter.begin(this);painter.drawPicture(0,0,picture);}

 重播图片：

注意重播只能使用.pic文件

 先绘制一个图形，保存为.pic文件

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter;QPicture picture;painter.begin(&picture);painter.drawEllipse(100,100,100,100);painter.end();picture.save("D:/picture.pic");painter.begin(this);painter.drawPicture(0,0,picture);  
}

然后进行重播

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter;QPicture picture;picture.load("D:/picture.pic");painter.begin(this);painter.drawPicture(0,0,picture);
}

QBitmap

QBitmap 类是一种单色屏幕外绘画设备，主要用于创建自定义QCursor和QBrush对象、构造QRegion对象以及为像素图和小部件设置蒙版。

QBitmap绘制图形：

void Widget::paintEvent(QPaintEvent *event)
{QPainter painter;QBitmap bitmap(200,200);painter.begin(&bitmap);painter.setBrush(Qt::cyan);painter.drawRect(0,0,100,100);painter.end();painter.begin(this);painter.drawPixmap(0,0,bitmap);
}