Kdelibs and KIconEffect porting (was Re: Which styles to keep?)

[Mosfet]

Moving on from styles a little bit, (I'll let that thread run a little bit to 
make sure there is consensus), I was looking around kdelibs and seeing what 
else needs porting. 

Most of this looks rather easy, just changing calls like rotate, contrast, and 
blend to their equivalent in either QImage/QPainter or Blitz. This does mean 
I am going to have to make kdeui require Blitz, tho. I assume this is okay 
since it was the whole reason for putting it in kdesupport ;-)

The one exception to my "easy" statement, besides styles, is KIconEffect. 
Because this used to reside in kdecore, not ui, it has it's copies of all 
it's effects. Since it's now in kdeui there is no reason for this so I'd like 
to port all this to QPainter/Blitz instead of it using it's own copies of 
effects. It also has some effects written using QImage::pixel() and 
setPixel(). I'd like to rewrite these as scanline methods for RGB(A) and 
premultiplied images if that's it's okay.

The authors are listed as Geert Jansen and Torsten Rahn. Can one of you guys 
email me and let me know it's okay to hack this?

The other thing that comes to mind is dithering. I was under the mistaken 
impression that Qt diffused dithered when converting to 32->8bit with 
palette. Don't know why I thought this, says it just uses nearest color right 
in the docs and I checked the sources just to be sure.

That means we'll still need to keep the dither method somewhere if we want to 
support 8bpp displays. I can add it to Blitz for now if needed, or we can 
stick it somewhere in kdeui. Personally, I think it belongs in 
QImage::convertToFormat(). Converting to 8bit without error diffusion isn't 
all that useful :P