[cairo] why cairo is so slow on Windows, is there any plan to improve cairo performance on Windows?

[Vladimir Vukicevic]

Note that the original author was referring to GDI+, not GDI -- GDI+ has 
full 2D API semantics, and is also not hardware accelerated anywhere. 
Cairo should always be at least as fast, and ideally faster, than GDI+; 
otherwise, that's a bug.

Is the issue that you're using the default filter, instead of setting 
the filter to FILTER_NEAREST, which is what I think GDI+ does?

     - Vlad

On 6/29/09 4:35 AM, Gerdus van Zyl wrote:
> The antialiasing has nothing to do with it. Rendering is normally fast
> when you have integer coordinates which with rotation you never have.
> Cairo works by falling back to it's own internal rendering if it can't
> get the correct output using the target backend (GDI). (which in this
> case is why it's slower than GDI)
>
> The cairo from the GTK website should be fine.
>
> Depending on what you are trying to render, caching the result in a
> long lived surface will help a lot. If you can describe what you are
> drawing we might be of more help.
>
> ~Gerdus
>
> On Mon, Jun 29, 2009 at 1:04 PM, Rainman Lee<rainman.lee at gmail.com>  wrote:
>> I do not need subpixel rendering, but I donot know how to disable it.
>> My test version is 1.8.6, and I got it from GTK web site.
>> Did you have tested cario_fill(a png) with rotation transforms from 0
>> to 360 degree?
>> It is very slow even if I set antialias with none.
>>
>> On Mon, Jun 29, 2009 at 4:38 PM, Gerdus van Zyl<gerdusvanzyl at gmail.com>  wrote:
>>> Nothing I know about. Firstly do you really need subpixel rendering?
>>>
>>> Where did you get your cairo? Newer versions are generally faster also
>>> check to see if it was compiled with SSE enhancement, etc.
>>>
>>> If the speed is a real problem you could always use GDI+ there are
>>> ways you can mix cairo and GDI rendering, though it won't be that
>>> easy.
>>>
>>> On Mon, Jun 29, 2009 at 6:48 AM, Rainman Lee<rainman.lee at gmail.com>  wrote:
>>>> Hi everyone,
>>>> I use cairo on windows for a while. I found that cairo was so slow
>>>> whenever fill a surface to another with scaling, rotating, or even a
>>>> non-integer translaton. I compared it with GDI+, which is at least 7
>>>> times faster than cairo :(
>>>>
>>>> It seems that if a source pixel can not map to a dest pixel which has
>>>> an integer coordinate, cairo will use a subpixel algorithm, and it
>>>> will terribly hurt the performance. I made a filling test, firstly by
>>>> a 0.5 pixel step horz translation transform, and a 1 pixel step horz
>>>> translation transform then, each of which looped 100 times. the first
>>>> case was extremely slow than the second one.
>>>>
>>>> Is there any idea to speed up cairo in this case? I tryed to set
>>>> antialias with none, but it had no effect.
>>>>
>>>> Thank you!
>>>>
>>>> Rainman.
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>>
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