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);elsedrawRightArrow(&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。