使用渐变效果之前画出来的图是正常的添加渐变效果之后图片少了一块但是我加了复合模式后效果也是正常的,这是为什么呢
代码如下:
QPen pen;
pen.setWidth(1);
pen.setStyle(Qt::SolidLine);
pen.setColor(Qt::red);
painter.setPen(pen);
//设置渐变效果
QLinearGradient linearGrad(0,0,100,0);
linearGrad.setColorAt(0,Qt::yellow);
linearGrad.setColorAt(0.5,Qt::green);
linearGrad.setColorAt(1,Qt::blue);
linearGrad.setSpread(QGradient::PadSpread);
painter.setBrush(linearGrad);
painter.setCompositionMode(QPainter::CompositionMode_Difference);
for(int i=0;i<36;i++){
painter.drawEllipse(QPoint(50,0),50,50);
painter.rotate(10);
}