C++ (Cpp) QGraphicsRectItem::rotation示例

示例#1

void MainWindow::resizeItem() {
for (int i = 0;  i < 10;  i++) {
    QGraphicsRectItem* theFrame = item1;
    QPointF P1(100 - (7.0 * i)/3.0, 50 -(5.0*i)/3.0);

    graphicsSheet->addPoint("P1", P1);
    graphicsSheet->addPoint("pos", theFrame->pos());

    QPointF P2i = QPointF(theFrame->rect().width(), theFrame->rect().height());
    QPointF P2 = theFrame->mapToScene(P2i);

    qDebug() << "P1:" << P1;
    qDebug() << "P2:" << P2;
    graphicsSheet->addPoint("P2", P2);

    QTransform t;
    t.rotate(-theFrame->rotation());
    t.translate(-P1.x(), -P1.y());

    QPointF P2t = t.map(P2);

//    qDebug() << "P2t:" << P2t;  // OK

/*************************/
    QPointF P3(P2t.x()/2, P2t.y()/2);
 //   qDebug() << "P3:" << P3;

    QTransform t2;
    t2.translate(P1.x(), P1.y());
    t2.rotate(theFrame->rotation());
    QPointF P3t = t2.map(P3);
////    qDebug() << "P3t:" << P3t;      // OK

    graphicsSheet->addPoint("P3t", P3t);

    QTransform t3;
    t3.translate(P3t.x(), P3t.y());
    t3.rotate(-theFrame->rotation());
    t3.translate(-(P3t.x()), -(P3t.y()));

    QPointF newPos = t3.map(P1);
    QSizeF newSize = QSizeF(P2t.x(), P2t.y());

    graphicsSheet->addPoint("newPos", newPos);

    RectItem* item1 = new RectItem(QRectF(newPos.x(), newPos.y(), newSize.width(), newSize.height()));
    qreal angle = 30;
    QPointF center2 = QPointF(item1->rect().width() / 2, item1->rect().height() / 2);
    item1->setTransformOriginPoint(center2);
    item1->setRotation(angle);
    graphicsSheet->scene()->addItem(item1);

}
}