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QGraphicsPixmapItem is not correctly updated when the pixmap is big.



  • I am trying to do an application to work on some of my astrophotos.

    But I have issues with the display of the big pictures.

    This is done of a QMainWindow with a QMdiArea where every QMdiSubWindow contains a QGraphicsView which shows a QGraphicsScene which contains just one QGraphicsPixmapItem. I do some zoom on this picture.

    If I set the mouse other the picture (1600x1200) and play with the wheel of my mouse, this will change the zoom of the picture. In the output of the application I see that every call to the QGraphicsView::paintEvent() is followed by a call to QGraphicsPixmapItem::paint()

    But now if I open a bigger picture (6000x4000) and then I play with the wheel of the mouse, I see that not every call to QGraphicsView::paintEvent() is followed by a call to QGraphicsPixmapItem::paint() which of course makes the picture disappeared.

    Could you please tell me what is going on ? Why did the pixmap is not updated ? What is the relation with the size of the picture ?
    Is there a way to force the call to QGraphicsPixmapItem::paint() each time I go through QGraphicsView::paintEvent() ?


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