QT学习 之 三维饼图绘制

void aaq::paintEvent( QPaintEvent* ev )
{
    QPainter painter(this);
    // 去除画笔
    painter.setPen(Qt::NoPen);
    // 设置反锯齿
    painter.setRenderHint(QPainter::Antialiasing);

    //******************************************** 圆饼图 *****************************************//
    if(1)
    {
        // 顶层圆面
        QRectF rect_top(10.0, 20.0, 280.0, 160.0);
        // 底层圆面
        QRectF rect_bottom(10.0, 60.0, 280.0, 160.0);
        // 中间矩形
        QRectF rect_midd(10.0, 100.0, 280.0, 40.0);

        // 扇形起始角度
        int startAngle = 230 * 16;
        // 扇形覆盖范围
        int spanAngle = 60 * 16;

        painter.setBrush(QColor(97,35,35,255));
        // 绘制底层圆面
        painter.drawEllipse(rect_bottom);
        // 绘制中间矩形
        painter.drawRect(rect_midd);

        painter.setBrush(QColor(Qt::darkYellow));
        // 绘制底层扇形
        painter.drawPie(rect_bottom, startAngle, spanAngle);

        // 扇形的弦与弧的交点
        double pi = 3.1415926;
        double dx1 = rect_top.width() * 0.5 * cos(230 * pi / 180);
        double dy1 = rect_top.height() * 0.5 * sin(230 * pi / 180);

        double dx2 = rect_top.width() * 0.5 * cos(290 * pi / 180);
        double dy2 = rect_top.height() * 0.5 * sin(290 * pi / 180);


        // 求交点的坐标值
        QPointF posBackCenter = QPointF(rect_top.center());
        double dX1 = posBackCenter.x() + dx1 + 0.5;
        double dY1 = posBackCenter.y() - dy1 + 0.5;

        double dX2 = posBackCenter.x() + dx2 + 0.5;
        double dY2 = posBackCenter.y() - dy2 + 0.5;

        // 记录交点
        QPointF topLeft = QPointF(dX1, dY1);
        QPointF bottomRight = QPointF(dX2, dY2) + QPointF(0,40);
        QPointF bottomLeft = topLeft + QPointF(0,40);
        painter.setBrush(QColor(Qt::darkYellow));

        // 绘制连接扇形的区域
        QPolygonF path;
        path << topLeft << QPointF(dX2,dY2) << bottomRight << bottomLeft;
        painter.drawPolygon(path);

        // 绘制顶层圆面
        painter.setBrush(QColor(156,56,56,255));
        painter.drawEllipse(rect_top);

        // 绘制顶层扇形
        painter.setBrush(QColor(Qt::yellow));
        painter.drawPie(rect_top, startAngle, spanAngle);
    }

    QWidget::paintEvent(ev);
}