QBrush之路径渐变画刷(Qt::BrushStyle::LinearGradientPattern)

void Widget::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event);

    QPainter painter(this);

    painter.fillRect(this->rect(),QBrush(QColor(255,255,255)));
    painter.setRenderHint(QPainter::Antialiasing);//抗锯齿

    QLinearGradient gradient(0,0,this->width(),0);
    gradient.setColorAt(0, Qt::red);
    gradient.setColorAt(1, Qt::blue);

    QBrush br(gradient);
    painter.setBrush(br);
    painter.drawEllipse(0,0,this->width()/3,this->height()/3);

    painter.drawEllipse(this->width()/3,this->height()/3,this->width()/3,this->height()/3);
    painter.drawEllipse(this->width()*2/3,this->height()*2/3,this->width()/3,this->height()/3);
}

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