GTKD Cairo get pixel color

[TheDGuy via Digitalmars-d-learn]

On Friday, 1 January 2016 at 19:32:40 UTC, Basile B. wrote:
> On Wednesday, 30 December 2015 at 23:20:23 UTC, Basile B. wrote:
>> On Wednesday, 30 December 2015 at 20:44:44 UTC, TheDGuy wrote:
>>> Hello,
>>>
>>> is there any way to get the pixel color of a single pixel by 
>>> x and y coordinates of a context?
>>
>> render to a png back buffer.
>>
>> see cairo_image_surface_create_for_data
>>
>> then you'll be able to access the data and, at the same time, 
>> to blit your buffer to screen.
>
>
> Actually I was thinking to a user defined buffer type:
>
> struct SurfaceBuffer
> {
>     void* data; // used as param to create the surface
>     Rgba[] opIndex(size_t index);
>     Rgba[][] scanline();
> }
>
> that you would pass as data in 
> cairo_image_surface_create_for_data().
>
> But gtk certainly has pitcure classes with the typical scanline 
> method and that you could use in 
> cairo_image_surface_create_for_data.

Ahm, i am not quite sure if you and [Mike Wey] talk about the 
same thing. And i posted the error message in my last post when i 
try to call "cairo_image_surface_create_for_data". I still don't 
know where i am able to call the function?