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List:       koffice-devel
Subject:    Re: Caching of shapes
From:       Thomas Zander <zander () kde ! org>
Date:       2007-10-30 16:05:51
Message-ID: 200710301705.51563.zander () kde ! org
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On Tuesday 30 October 2007 16:40:30 Johannes Simon wrote:
> Am Dienstag, den 30.10.2007, 10:54 +0100 schrieb Thomas Zander:
> > This leads to some questions;
> > * does the chart shape optimize redrawing?
> > This means;
> >   o only call update() for the areas that need it (i.e use the QRectF
> > arg)
>
> The chart shape currently doesn't have an update(QRectF) method. At what
> point, other than shape-internally, is that function used?

Sure you do, its a method on the KoShape class.


> > * Will this be useful for shapes other then the chart shape, painting
> > text turned out to be fast enough and painting a krita shape is already
> > cached internally (etc), so a shape should be able to turn it off for
> > sure. But I just want to check if its worth it for shapes other then the
> > kchart one.
>
> Neither the text shape, nor a simple eclipse path shape, nor any other
> shape repaints at an acceptable speed at zoom levels of >=200%. 

Interresting, on my 2 years old laptop I have no problems with painting speed 
at all (and this laptop makes Krita crawl).
How do you define 'acceptable speed' ?

> I'm not sure if we need a KoRepaintManager. In KoShape, there's
> basically four things we need:
>  * a pixmap

That can't work, a shape holds the data for any number of views, and naturally 
you don't want a 2000% zoomed pixmap to be painted on a 15% zoomed view.  So 
the pixmap has to be cached outside of the shape.  Which is what the repaint 
manager was there for.

>  * a method that marks this cache as invalid

That is exactly what the old one already did; it marked it invalid as soon as 
the user called one of the KoShape::update() methods.

>  * a paint() function that paints the pixmap onto the screen, and
> updates it if requested
>  * and an optional method that disables caching

So, I agree on your approach in general lines.  But I still think you should 
look at the repaintManager since those ideas at one point have been coded 
into that some time ago :)
-- 
Thomas Zander

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