GTKD Cairo get pixel color

[TheDGuy via Digitalmars-d-learn]

On Monday, 4 January 2016 at 19:27:48 UTC, Mike Wey wrote:
> I think you are looking for something like this.
>
> Context.getTarget will get you the surface the Context is 
> drawing to, this most likely isn't a ImageSurface.
> So you will need to create an pixbuf from the returned surface, 
> with the Pixbuf you can then get the raw pixel data using 
> getPixelsWithLength().
>
> ```
> import gdk.Pixbuf;
>
> bool drawCallback(Scoped!Context cr, Widget widget)
> {
>     GtkAllocation size;
>     Pixbuf surafce;
>
>     getAllocation(size);
>
>     //Draw something;
>
>     surface = getFromSurface(cr.getTarget(), 0, 0, size.width, 
> size.height);
>
>     ubyte[] data = cast(ubyte[])surface.getPixelsWithLength();
>
>     //Do somthing with data.
>
>     return true;
> }
> ```
>
> getPixelsWithLength has the wrong return type, which will 
> probably be fixed some time.

Thank you very much! But surface.getPixelsWithLength() only gives 
me an array with 16 fields (with a 256x256 DrawingArea)?

I also tried to save the Pixbuf with:

string[] options = ["quality"];
string[] opval = ["100"];
surface.savev("C:\\Users\\Standardbenutzer\\Desktop\test.jpeg", 
"jpeg", options, opval);

but i found absolutely NOTHING about the options or the option 
values i have to set, therefore i get an invalid argument 
exception :(