[Interest] double-buffering, quality drop

[Felix morack]

not sure how the graphicsitem comes into all of this, but no you cant draw
on it. you can draw on a QGraphicsWidget or you can derive from
QGraphicsItem and draw in its paint() method.

2015-02-03 23:47 GMT+01:00 Alexander Semke <Alexander.Semke at web.de>:

> 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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