[Interest] double-buffering, quality drop

Alexander Semke Alexander.Semke at web.de
Tue Feb 3 23:47:59 CET 2015


Am Dienstag, 3. Februar 2015, 11:36:55 schrieb Felix morack:
> we had a similar problem. We solved it by having the updatePixamp()
> function set a flag and doing the actual drawing the in paint() method, ie:
> [...]

This is what Michael also suggested. I tried it, the quality of the pixmap is 
much better now. But how can I switch between painting on a QPixmap und on 
QGraphicsItem?

Now I do in Curve::paint()

if (dirty) {
	painter->begin(m_pixmap);
	//drawing
	painter->end();
	dirty = false;
}

painter->begin(this); 
drawPixmap(boundingRectangle.topLeft(), m_pixmap);
painter->end();

The second begin()-call doesn't work here since QGraphicsItem is not derived 
from QPainterDevice. Did you also used QGraphicsItem?


-- 
Alexander



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