[cairo] Any plan to address the 32768px limit ?

[Uli Schlachter]

Hi,

Am 23.07.21 um 23:29 schrieb ChameleonScales:
[...]
> Is there any intention to change that in order to support larger images?

For me personally: Nope, I have no such intention.

> Otherwise could the source code be easily edited to make a custom build of Cairo with an increased limit?

Well, not easily, I guess. According to the comment next to the limit
[0], this limit exists because pixman has an API using a 16.16 format.
I don't know how much of the API exists in which version, but apparently
there are several fixed point formats in pixman [1]. However, searching
for e.g. "pixman_fixed_32" in pixman.h produces basically no hits while
pixman_fixed_t appears everywhere.

(IIRC cairo mostly uses a 24.8 format, but I am not entirely sure.)

So, I guess you first need to change pixman's API and then port cairo to
that new API.

Cheers,
Uli

[0]:
https://gitlab.freedesktop.org/cairo/cairo/-/blob/994eccefc0a778d291a8dbbb4143280b38a7ad80/src/cairo-image-surface.c#L58-62
[1]:
https://gitlab.freedesktop.org/pixman/pixman/-/blob/aaf59b0338fbd4b9142794254261f8d0a018b60c/pixman/pixman.h#L115-123

-- 
<alanc> I think someone had a Xprint version of glxgears at one point,
    but benchmarking how many GL pages you can print per second
    was deemed too silly to merge