Qt之在QGraphicsView中繪圖

#include <QPainter>
void MyView::paintEvent(QPaintEvent * event)
{
    qDebug("************MyView::paintEvent*****************");
   // QPainter painter;  //QWidget::paintEngine: Should no longer be called
    QPainter painter(this->viewport());  //關鍵這一句
    
    QLinearGradient ling(QPointF(70, 70), QPoint( 140, 140 ) );  //從起點到終點的漸變
    ling.setColorAt(0, Qt::blue);  //起點到中心要顯示的顏色
    ling.setColorAt(1, Qt::green);
    ling.setSpread( QGradient::PadSpread );   //默認顯示模式

    QBrush brush(ling);
    painter.setBrush(brush);
    painter.drawRect(0, 0, 200, 200);

    painter.end();
    QGraphicsView::paintEvent(event);
}