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

[Rainman Lee]

Hi,
yes, I want users see an animation, not pictures, so I have to update
the screen as soon as possible.

Here is my test result:
kept my test code no change, the total elapsed time was 5652ms
replaced CAIRO_FORMAT_ARGB32 with CAIRO_FORMAT_RGB24, the total time was 4124ms
finally set the tarContext operator as CAIRO_OPERATOR_SOURCE, the
total time was 3892ms
I just wonder whether we should use a buffer surface, because without
it, the total time was only 2987ms, but still far behind GDI+, which
score is 1259ms...
Is there any possible to opitmize more ?

Thank you!

Rainman.



On Tue, Jun 30, 2009 at 12:36 PM, Vladimir Vukicevic<vladimir at pobox.com> wrote:
> On 6/29/09 8:34 PM, Rainman Lee wrote:
>>
>> I tried, it was more slower.....here is my test code
>>
>>        HDC hdc = GetDC(m_hWnd);
>>        RECT rcClient; GetClientRect(m_hWnd,&rcClient);
>>
>>        // create all drawing surfaces
>>        cairo_surface_t* srcSurface =
>> cairo_image_surface_create_from_png("ren.png");
>>        cairo_surface_t* bufSurface =
>> cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 1440, 900);
>
> Use CAIRO_FORMAT_RGB24 -- you don't need alpha, as your final surface won't
> have alpha.
>
>>        cairo_surface_t* tarSurface = cairo_win32_surface_create(hdc);
>>
>>        // create all drawing contexts
>>        cairo_t* bufContext = cairo_create(bufSurface);
>>        cairo_t* tarContext = cairo_create(tarSurface);
>>
>>        // create source pattern
>>        cairo_pattern_t* srcPattern =
>> cairo_pattern_create_for_surface(srcSurface);
>>        cairo_pattern_set_filter(srcPattern, CAIRO_FILTER_FAST);
>>
>>        // initialize the buffer context
>>        cairo_translate(bufContext, 600, 300);
>>        cairo_set_antialias(bufContext, CAIRO_ANTIALIAS_NONE);
>>
>>        double angle = M_PI / 180;
>>
>>        for (int i = 0; i<  360; i++)
>>        {
>>                // paint on the buffer
>>                cairo_rotate(bufContext, angle);
>>                cairo_set_source(bufContext, srcPattern);
>>                cairo_paint(bufContext);
>>
>>                // then fill the target with buffer
>>                // no rotation
>>                cairo_rectangle(tarContext, 0, 0, rcClient.right,
>> rcClient.bottom);
>>                cairo_set_source_surface(tarContext, bufSurface, 0, 0);
>>                cairo_fill(tarContext);
>
> Er, why are you drawing this inside the loop?  Or are you trying to animate
> the rotation as quickly as possible?
>
> Either way, you want to use cairo_set_operator(tarContext,
> CAIRO_OPERATOR_SOURCE) -- otherwise you get the default OVER, and will be
> doing alpha blending.
>
>>        }
>>
>>        // destroy the source pattern
>>        cairo_pattern_destroy(srcPattern);
>>
>>        // destroy all drawing contexts
>>        cairo_destroy(bufContext);
>>        cairo_destroy(tarContext);
>>
>>        // destory all drawing surfaces
>>        cairo_surface_destroy(srcSurface);
>>        cairo_surface_destroy(bufSurface);
>>        cairo_surface_destroy(tarSurface);
>>
>>
>>        ReleaseDC(m_hWnd, hdc);
>>
>> Is there any code I can optimize?
>
> Try those two changes and let me know how it goes.
>
>    - Vlad
>