QGraphicsView and QGraphicsItem: don´t scale item when scaling the view rect

Question

Hi, I am using Qt´s QGraphicsView- and QGraphicsItem-subclasses. is there a way to not scale the graphical representation of the item in the view when the view rectangle is changed, e.g. when zooming in. The default behaviour is that my items scale in relation to my view rectangle.

I would like to visualize 2d points which should be represented by a thin rectangle which should not scale when zooming in the view. See a typical 3d modelling software for reference where vertex points are always shown at the same size.

Thanks!

Answer 1

How about this:

#include <QtGui/QApplication>
#include <QtGui/QGraphicsScene>
#include <QtGui/QGraphicsView>
#include <QtGui/QGraphicsRectItem>

int main(int argc, char* argv[]) {
    QApplication app(argc, argv);
    QGraphicsScene scene;
    scene.addText("Hello, world!");
    QRect rect(50, 50, 100, 100);
    QGraphicsRectItem* recti = scene.addRect(rect);
    QGraphicsView view(&scene);

    // Set scale for the view
    view.scale(10.0, 5.0);

    // Set the inverse transformation for the item
    recti->setTransform(view.transform().inverted());

    view.show();
    return app.exec();
}

As you can see the text is scaled up but the rectangle is not. Note that this does not only prevent the scaling for the rectangle but and other transformation.

Answer 2

Set the item's flag QGraphicsItem::ItemIgnoresTransformations to true does not work for you?