Re: Antialiasing rendering of pixbufs

[D M German <dmg uvic ca>]

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
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