代码如下
void MainWindow::paintEvent(QPaintEvent * qPEvent){
QPalette pal;
QPixmap backgroundPix;
QPainter painter(this);
backgroundPix.fill(QColor(0,0,0));
painter.drawLine(QPoint(0,0),QPoint(280,280));
painter.drawPixmap(0,0,100,100,backgroundPix);
}