GTKD Cairo get pixel color

[TheDGuy via Digitalmars-d-learn]

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.

Thanks for your answer. But how do i access the function via the 
context?

It does not work like this:

class DW:DrawingArea{
	this(){
		addOnDraw(&drawCallback);
	}
	bool drawCallback(Scoped!Context cr, Widget widget){
		char[] c = new char[](256*256);
		auto val = 
cr.cairo_image_surface_create_for_data(c,cairo_format_t.CAIRO_FORMAT_ARGB32, 256,256, cairo.format_stride_for_width(cairo_format_t.CAIRO_FORMAT_ARGB32,256));
		return true;
	}
}
"no property 'cairo_image_surface_create_for_data' for type 
'Scoped'"