Qt 渐变色条

/************************************************
 * Class: ColorWidget
 *
************************************************/
class ColorWidget : public QWidget
{
    Q_OBJECT
public:
    explicit ColorWidget(QWidget *parent = nullptr);

signals:

public slots:

private:
    void paintEvent(QPaintEvent *);
};

/************************************************
 * Class: ColorWidget
 *
************************************************/
ColorWidget::ColorWidget(QWidget *parent) : QWidget(parent)
{

}

void ColorWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing,true);
    QLinearGradient Linear(0,0,this->width(),this->height());        //垂直渐变

    Linear.setColorAt(0,Qt::red);
    Linear.setColorAt(0.33,Qt::yellow);
    Linear.setColorAt(0.46,Qt::green);
    Linear.setColorAt(1,Qt::blue);

    painter.setBrush(Linear);
    painter.setPen(Qt::transparent);
    painter.drawRect(0,0,this->width(),this->height());          //100,100 到200,200
}