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List:       koffice-devel
Subject:    Re: Painting on the QImage in QPainter Canvas
From:       Ariya Hidayat <ariya () kde ! org>
Date:       2009-08-15 7:17:06
Message-ID: ba035dd10908150017n44837125rff35e11ac8563915 () mail ! gmail ! com
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> This will repaint entire canvas, even in case we change only a tiny
> rect.

This can be remedied by using the updated rect only. Hint: the
argument to the paintEvent() is there for a reason, so check the
documentation on QPaintEvent.

> More that that, why do we need an additional temp object in a
> repaint chain?

I haven't seen Krita code, but the usual way to overcome this problem
is to have a persistent "scratch" QImage. Of course this QImage needs
to grow and shrink (but not aggressively) according to the said
updated rect.



-- 
Ariya Hidayat, Nokia
http://www.linkedin.com/in/ariyahidayat
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