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Qt-interest Archive, August 2007
QGraphicsItem rotate & paint

Message 1 in thread

Hi all...

I have a problem with QGraphicsItem: it seems that if I rotate the
coordinate systems, it takes more and more time to refresh the screen...
it this normal ? viewimage is re-evaluated elsewhere and only then
needed, so the paint function need only to draw it.

 thanks a lot,

        Giampaolo

---- sample code ----

void NShapeRaster::paint(QPainter *painter, const
QStyleOptionGraphicsItem *option, QWidget *widget)

{
   int w, h;
   qreal alfa;

   alfa = getRotation();
   w = viewimage.width();
   h = viewimage.height();

   painter->rotate(alfa);  <--- rotating slow down the refresh

   painter->drawImage(-w/2, -h/2, viewimage);
}


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