[cairo] API Shakeup: default matrix (axes and origin)

[Carl Worth]

On Sun, 27 Feb 2005 12:00:32 +0100, Øyvind Kolås wrote:
> The regular computer graphics way of describing a coordinate system
> only has the advantage of familiarity for people that are familiar
> with the memory layout used for linear frame buffers.

No, there's quite a bit more to it than that.

Every raster image format that I'm familiar with has Y down. As well
as almost every 2D graphics system that I've ever seen. Even SVG has
the same default coordinate system as cairo.

I think if you ask someone who has had to write a program that
simultaneously draws with GDK, (Y downwards), and libgnome-print, (Y
upwards), they'll tell you that libgnome-print is the one that feels
backwards. My survey results with this question are 100%, (though my
sample size is still only one).

> An even more extreme option, would be to place the origin in the
> middle of the surface. This will make some vectorial drawing simpler,
> but I have not put a large amount of thought into it.

Heh. I don't think that's a workable option, (in spite of the fact
that getting the direction of the Y axis is much more likely to put
some "ink" on the screen). This approach would just mean that nobody
is happy with the default matrix.

-Carl

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