Re: Antialiasing rendering of pixbufs

[dmg <dmg uvic ca>]

I forgot to add. I have been fixing our code to make sure the pixbuf
is always placed in a pixel boundary, with respect to the top,corner
of the canvas.

My hypothesis for the blurring is that the scrolling seems  to place
it in an offset of the visible canvas that is a subpixel coordinate,
making it blurry.

what would you recommend is a way to fix this?

--daniel

On Tue, Oct 15, 2013 at 11:21 PM, dmg <dmg uvic ca> wrote:
> 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



-- 
--dmg

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