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Emiliano Torres
Asked: 2020-06-01 06:39:46 +0800 CST 2020-06-01 06:39:46 +0800 CST

Rotate QGraphicsItem - Does not rotate about its center

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I'm trying to rotate a QGraphicsItem about its own center, so that its center doesn't move, it just rotates X degrees...I can't get it to happen, it changes places, as if the whole scene rotates but the rest of the elements don't rotate ...but he rotates but not about his center. I leave the code to see if they give me a hand. Thanks a thousand.

QRectF rect;
rect = engine->boundingRect();
QPointF center = rect.center();
qreal angle = grade;
QTransform t;
t.translate(center.x(), center.y());
t.rotate(angle);
t.translate(-center.x(), -center.y());
engine->setPos(t.map(engine->pos()));
engine->setRotation(engine->rotation() + angle);

Engine is the QGraphicsItem that I want to rotate about its center...

c++

1 Answers

  1. Best Answer

    Thanks to the note from @Trauma, I leave you here how I solved my problem in case it helps someone. All of the code in the question I simply replaced with the following:

    engine->setTransformOriginPoint(engine->boundingRect().center());
engine->setRotation(engine->rotation() - grade);
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