Mipmapping for canvas. Ideas and comments.

Dmitry Kazakov dimula73 at gmail.com
Tue Jul 21 21:13:53 CEST 2009

>> 3) KisPresceledProjection::Private::prescaledQImage vs
>>   KisPresceledProjection::Private::prescaledQPixmap?
>> What is the difference and where are they mostly used?
> Pixmaps reside on the xserver and are fast to paint over and over again
> Images reside on the client and are good if you need to poke at the pixels or
> change it every time you display it
> An image will be converted to a pixmap internally before being drawn on
> your screen, and this conversion is usually quite expensive.

Does it mean that if we draw onto pixmap directly, the system will
work faster? And what are the looses of this approach?

> As to the levels and scaleX/scaleY. I think that the pyramid should just
> scale with a factor of 2 (in both x and y) for each step. You should then take
> the closest image and apply the scaleX/scaleY.

It's good idea, but i thought to store nearest zoomlevels that we got
from ~KoZoomController to eliminate scaling during requests at all. Is
it possible? And which scaling algos are better to use in such a case?
Do you know some books/articles to read about it?

Dmitry Kazakov

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