Set color to a single point in Cairo

[Basile B. via Digitalmars-d-learn]

On Sunday, 20 December 2015 at 11:16:06 UTC, TheDGuy wrote:
> On Sunday, 20 December 2015 at 01:17:50 UTC, Basile B. wrote:
>> On Saturday, 19 December 2015 at 14:16:23 UTC, TheDGuy wrote:
>>> is it possible to set the color of a single pixel with Cairo?
>>
>> Not like you would do with a classic canvas (2d grid), because 
>> colors are applied with `cairo_fill()` and `cairo_stroke()` on 
>> a particular path.
>>
>> but you can define a path that represents a single pixel and 
>> fill it:
>>
>> ```
>> cairo_rectangle (cr, x, y, 1, 1); // 1 pix rectangle
>> cairo_set_source_rgba (cr, 0, 0, 0, 1); // color
>> cairo_fill (cr); // fill the rectangle with source rgba
>>
>> ```
>>
>> However cairo is node made to be used like this. The workflow 
>> is usually more based on stacked layers (1 layer = 1 path) 
>> with different filling, different transparency.
>
> Thanks for your answer,
>
> but a bit disappointing that cairo doesn't offer a real 
> "setPixel" function :(

Vectorial graphics are like that, they are at a higher level 
than, for, example, open GL. My experience with such libraries is 
a bit dusty (for example I made this when I was younger: 
http://4.bp.blogspot.com/-cmzQAHlaE50/TxcG3vEAA9I/AAAAAAAAQS0/qFxVLeo1JGU/s1600/GrainPlot%2Bv.2.4.jpg, here it plots some variable shape segments defined by x³-ax²+ax) but I clearly remember that you **never** need to draw a single pixel. A point is either part of the fill or of the border, I mean **always**.

However not that internaly cairo uses "pixman" but IDK if you can 
access it directly.
(see http://www.pixman.org/)