[cairo-bugs] [Bug 20091] Polygon clipping to surface fails for large coordinate values, limitations of the API not documented.

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Wed Nov 8 22:07:08 UTC 2017


--- Comment #8 from Stefan <stef_sport_2002 at yahoo.it> ---
I found the same problem, this (undocumented) limitation on the coordinate
system severely limits the usability of the library for 'serious projects' like
CAD software. In-memory surfaces (like the ones created with
cairo_image_surface_create) have limitations on the coordinate system *well*
below the claimed (and already limited) 24.8 bit fixed point space. 
For example, the following:
   cairo_move_to(ctx, -200000., -200000.);
   cairo_line_to(ctx, 200000., 200000.);
clearly crossing the clip area will not be displayed.
Since in-memory surfaces are used for double buffering this limits the overall
manageable space, even if user coordinates for screen surfaces can go (maybe?)
up to +/- 8Mpixels.

It was really frustrating to discover that a 2D api with double precision
coordinates is internally restricted to 20.something bits.


You are receiving this mail because:
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cairographics.org/archives/cairo-bugs/attachments/20171108/48b241f1/attachment.html>

More information about the cairo-bugs mailing list