krita overview

Patrick Julien freak at
Mon Oct 13 10:56:52 CEST 2003

On October 13, 2003 07:08 am, Boudewijn Rempt wrote:
> On Mon, 13 Oct 2003, Michael Thaler wrote:
> > I think the whole point about the dirty bool is to mark a tile as
> > modified if the tile is changed. If the screen is redrawn, only tiles
> > which are actually modified are redrawn. Just think about a freehand
> > tool that just sets a pixel. For every pixel, right now, all tiles
> > have to be redrawn. Since this implies a conversion from a QImage to
> > QPixmap which is supposed to be slow, it is really inefficient. If the
> > dirty-bool is set probably and the code that actually renders the
> > image to the screen, respects the dirty-bool of the tiles, it only
> > renders one tile at one time in the case of the freehand tool. It is
> > much more efficient (I wonder why a tile size of 64 x 64 is used here?
> > It would probably be better to use 32 x 32 or 16 x 16 tiles because
> > then, in the case of the freehand tool, less data has to be drawn to
> > the screen and for other tools, the overhead of more tiles is not that
> > big, isn't it?)
> Well, I did experiment with that, and if you look at the
> I sent you (I did attach that file, didn't I?), you'll see that I try to
> invalidate only the rect that's painted. When I added that, instead of
> invalidating the whole image, flicker decreased visibly, so I thought
> repainting only part of the canvas was already supported.

yep, it's supported

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