[Mono-winforms-list] MWF painting VERY slow compared to .NET

[Peter De Jager]

> Here are my results:
...

Thank you for looking into it. More or less the same picture, although your
Linux results are significantly faster than mine. Is this due to NLD vs.
FC4?

> My conclusions:
> * While we are a bit slower with our MWF dll, it's pretty 
> obvious that the bottleneck is not MWF, but the drawing code.

I don't know what is involved in optimising the drawing code, so I'm not
sure if this is good news or bad news ;-)

> * As someone just put it, I'd say it's pretty obvious that 
> Cairo "sucks donkey ass" when it comes to handling large 
> images. This is on Cairo 0.3.0 , which was absolutely not 
> optimized. Cairo is currently at version 0.5.0 and we have 
> someone who's moving our libgdplus to that newer version. 
> Once that is complete we can compare (and look into 
> optimizations on the cairo or our libgdiplus side) One caveat 
> here: It might be X itself that sucks donkey ass with large 
> images, maybe I find some time to test that tonight.

I paint bitmaps where possible since this is the .NET recommended approach
for speed. In the sample code the image is loaded only once and then
repeatedly painted, so I don't understand the slowdown (Cairo or X) in terms
of handling large images. I would have thought that it is purely a function
of the number of pixels being blitted to the screen (i.e. the drawing code).

Pete.