Re: Antialiasing rendering of pixbufs

[dmg <dmg uvic ca>]

Hi Damon

I think I found the reason. I thought I had made sure that the pixbufs
were placed exactly at a pixel boundary (converting position in canvas
coordinate to pixel, rounding the pixel, then back to canvas
coordinates).

they werent all of them. Now that I fix that it seems to have solved problem.

Sorry for the noise, and thanks for your help,

--daniel

On Wed, Oct 16, 2013 at 10:16 AM, D M German <dmg uvic ca> wrote:
> Hi Damon,
>
>  Damon> On Tue, 2013-10-15 at 23:27 -0700, dmg wrote:
>  >> 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?
>
>  Damon> I think GooCanvas only scrolls by integer numbers of pixels - it moves
>  Damon> around a child GdkWindow to do the scrolling, and that can only be done
>  Damon> in pixels.
>
>  Damon> So I'm not sure what is causing your problem. Both pictures look a bit
>  Damon> blurry to me. Maybe the image is being scaled a tiny bit accidentally?
>
> I thought so originally, so I exported the pixbuf and compared it
> against what is on the screen.
>
> Look at these files:
>
> http://turingmachine.org/~dmg/temp/goocanvas/
>
> original is the pixbuf that is to be rendered.
>
> before is the goocanvas with that pixbuf when it looks "blurry".
>
> after is the goocanvas with the pibxuf when it looks good.
>
> I made crops that show it more (see directory crops). The difference is
> subtle.
>
> The only difference between "before" and "after" is pressing the down key
> twice. I am almost certain we don't do anything when the down key is
> pressed.
>
> thanks again for any insight into this,
>
> --daniel
>
>
>  Damon> Damon
>
>
>
> --
> Daniel M. German                  "A coin symbolizes our free will"
>                                    El Zahír, Jorge Luis Borges
> http://turingmachine.org/
> http://silvernegative.com/
> dmg (at) uvic (dot) ca
> replace (at) with @ and (dot) with .



-- 
--dmg

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