Mipmapping for canvas. Ideas and comments.

[Matthew Woehlke]

Dmitry Kazakov wrote:
> The tile engine has already come  over to a quite stable state by this
> moment.  I  think today  i'll publish patches  for trunk.  So  now i'm
> publishing my ideas about mipmapping feature of viewing mechanism.
> 
> Well, mipmapping  could be added  in two parts  of krita: the  first -
> before actual merging and the second - after merging.
> 
> 
> * The first could be done  inside KisPaintDevice class and all merging
>  would be done with prescaled images.
> 
> Pros:
>      + we merge only small images, not fullsized big ones
>      + as a consequence, filter layers and masks are applied much
>        faster

Cons: filter layers will be wrong? Color filters, no, but how do you 
even attempt to apply a custom convolution filter to an input that is 
half resolution and expect to get anything even remotely correct? (Or do 
you decide per-filter if it can be applied to downsampled input? Would 
that even be possible?)

Consider especially that "filter layer" may in the future include 
debayer, which would be hideously, hideously broken by applying it to a 
downsampled input.

-- 
Matthew
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