QT笔记 - QPainter 填充环形区域（甜甜圈）

以矩形为例：

    QPainter painter(this);
    // painter.setPen(Qt::blue);
    // painter.setFont(QFont("Arial",30));
    // painter.drawText(rect(),Qt::AlignCenter,"Hello Qt!!!");

    QRect rect = QRect(50, 50, 400, 400);
    QRect box = QRect(100, 100, 105, 63);
    QColor maskColor(255, 0, 0, 255);
    QColor fontColor(0, 139, 139, 255  );

    QPainterPath path;
    path.addRect(rect);//添加路径
    path.addRect(box); //添加路径
    QPainterPath subRect;
    subRect.addRect(box);
    path.subtracted(subRect);//减去路径及其所包含的区域

    painter.fillRect(box,fontColor);
    painter.fillPath(path, maskColor);