[prev in list] [next in list] [prev in thread] [next in thread] 

List:       cairo
Subject:    Re: [cairo] problem with downscaling images
From:       Bill Spitzak <spitzak () thefoundry ! co ! uk>
Date:       2007-05-30 9:33:41
Message-ID: 465D44F5.7020605 () thefoundry ! co ! uk
[Download RAW message or body]

Behdad Esfahbod wrote:
> On Tue, 2007-05-29 at 14:14 -0400, Daniel Amelang wrote:
>> On 5/28/07, Vladimir Vukicevic <vladimir@pobox.com> wrote:
>>> The problem seems to be that pixman transformation matrices are 16.16
>>> fixed; thus the scaled offsets end up overflowing.
>> Carl has been threatening to make cairo fixeds 24.8. Maybe pixman
>> fixeds should also be made 24.8 when that happens.
>>
>> Dan Amelang
> 
> There should be a better fix possible in this case.  Not sure how
> exactly, maybe extract the integer part of the offset into a full int or
> something.

That may work very well, because a flag could also be kept that 
indicates whether the remaining matrix is the identity or not, and avoid 
the matrix mulitply in those cases.
_______________________________________________
cairo mailing list
cairo@cairographics.org
http://cairographics.org/cgi-bin/mailman/listinfo/cairo
[prev in list] [next in list] [prev in thread] [next in thread]