Zooming out a QGraphicsView is crashing

Question

I have a custom QGraphicsScene class that I want to scale when doing some mouse movements. The scaling works fine whenever the factor is >= 1.0. But when the factor is smaller than one, then it crashes because of (I believe a loop).
Here is the code handing the zoom and explaining the loop:

 void NodeScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
    {
// Start of function
        QPointF newCoord=event->scenePos();
        if (zooming) // Zooming only set to true when using right mouse button with Alt-key pressed
        {
            mainView->setTransformationAnchor(QGraphicsView::AnchorUnderMouse);

            // Scale the view / do the zoom

            if(newCoord.x()>lastMouseCoord.x())
            {
                // Zoom in
                mainView->scale(1.03f, 1.03f);

            }

            if(newCoord.x()<lastMouseCoord.x())
            {
                // Zoom out
                mainView->scale(0.97f, 0.97f); --> Goes back to start of function and then zooming out again and then start of function... etc... until crashing
            }

            lastMouseCoord=newCoord;

        }

    }

Any idea why zooming out is going to start of function immediately ? Thanks

score 0 · Accepted Answer · answered Oct 21 '15 at 08:09

0

I had to implement the initialization of a global variable before the zoomout function, and if this variable was initialized when entering the mouseMoveEvent, then I would directly exit the function.

answered Oct 21 '15 at 08:09

Laurent Crivello

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Zooming out a QGraphicsView is crashing

1 Answers1