由于对当前项目需要绘制一个箭头控件，所以使用了QPainter和QPolygon来进行绘制，原理就是计算填充，下面贴出代码和效果图

这里简单介绍下QPolygon
QPolygon是继承自

QVector<QPoint>

那么可以很简单的理解为，他就是一个点的集合
所以由3个点就构成了一个箭头，当然更复杂的箭头大家可以自己去进行构建，由于我的项目需要的只是单纯箭头就展现如下代码，我还填充了一个矩形框作为背景。

void arrowWidget::paintEvent(QPaintEvent* event)
{
    QPainter painter(this);
    painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
    int cornerRadius = qMin(this->width(), this->height()) / 10; 

    
    QRect rect(10, 10, this->width() - 20, this->height() - 20); 
    painter.setPen(Qt::NoPen);
    painter.setBrush(QColor(85, 114, 128));  
    painter.drawRoundedRect(rect, cornerRadius, cornerRadius);   
    painter.setBrush(Qt::lightGray); 
    //drawcaricon(&painter);

    if (leftArrow)
        drawLeftArraow(&painter);
    else
        drawRightArrow(&painter);
}


void arrowWidget::drawLeftArraow(QPainter* painter)
{

    QPoint center(this->width() / 2, this->height() / 2);

    
    int arrowWidth = this->width() * 0.2; 
    int arrowHeight = this->height() * 0.2; 


    QPoint left(center.x() - arrowWidth, center.y());    
    QPoint top(center.x() + arrowWidth / 2, center.y() - arrowHeight); 
    QPoint bottom(center.x() + arrowWidth / 2, center.y() + arrowHeight);


    QPolygon arrow;
    arrow << left << top << bottom;

 
    painter->drawPolygon(arrow);
}

void arrowWidget::drawRightArrow(QPainter* painter)
{

    QPoint center(this->width() / 2, this->height() / 2);

   
    int arrowWidth = this->width() * 0.2; 
    int arrowHeight = this->height() * 0.2;


    QPoint right(center.x() + arrowWidth, center.y());   
    QPoint top(center.x() - arrowWidth / 2, center.y() - arrowHeight); 
    QPoint bottom(center.x() - arrowWidth / 2, center.y() + arrowHeight); 


    QPolygon arrow;
    arrow << right << top << bottom;

    painter->drawPolygon(arrow);
}

这是效果图，有需要其他操作的可以自己根据实际情况调整。