1 void Widget::paintEvent(QPaintEvent *event) 2 { 3 Q_UNUSED(event); 4 5 QPainter painter(this); 6 7 painter.fillRect(this->rect(),QBrush(QColor(255,255,255))); 8 painter.setRenderHint(QPainter::Antialiasing);//抗锯齿 9 10 QLinearGradient gradient(0,0,this->width(),0); 11 gradient.setColorAt(0, Qt::red); 12 gradient.setColorAt(1, Qt::blue); 13 14 QBrush br(gradient); 15 painter.setBrush(br); 16 painter.drawEllipse(0,0,this->width()/3,this->height()/3); 17 18 painter.drawEllipse(this->width()/3,this->height()/3,this->width()/3,this->height()/3); 19 painter.drawEllipse(this->width()*2/3,this->height()*2/3,this->width()/3,this->height()/3); 20 }
以上代码中第10行形参为控制渐变方向，当x1=x2时为垂直渐变，当y1=y2时为水平渐变，以下两图分别展示水平渐变及垂直渐变效果
