Antialiasing rendering of pixbufs

[dmg <dmg uvic ca>]

Hi Damon, everybody,

We have a bit of a challenge with subpixel antialising of pifbufs.

Let me explain what the problem is.

We render PDFs  into pixbufs exactly at the resolution we need.
The goo_canvas displays them without any antialiasing (ie. blurring)
if and only if the pixbuf is placed exactly in a pixel boundary.

The problem is when one scrolls. It appears as if the scrolling moves
the pixbuf into a subpixels location. This means that in some cases
the pixbuf appears slightly blurry. Keep scrolling, and the pixbuf is
nicely rendered again.

Here are two screenshots that show the problem:

This is the pixbuf when it is blurred:

http://turingmachine.org/~dmg/temp/before.png

and this is just after scrolling up with the keyboard. nothing has
been modified in the pixbuf.


http://turingmachine.org/~dmg/temp/after.png

Is there any way to force pixbufs to always be placed in pixel
boundaries to avoid the antialiasing effect?

thanks again for helping us. We are almost done with the porting!



-- 
--dmg

---
Daniel M. German
http://turingmachine.org