Previously we were using the cairo_fixed_t type which meant we've
historically only been using 16 bits of precision for these offsets,
and recently only 8 bits. Meanwhile, all manipulatons of offsets
have been in floating-point anyway, so we might as well store them
that way.
This change also prevents a rendering regression introduced with the
24.8->16.16 change betwen snapshots 1.5.10 and 1.5.12 .
This change affected gradient-rendering details for the clip-operator
and operator-source tests, so the corresponding reference images are
updated here.
The additional 8 bits of integer allows device space to be 256
times larger before applications need to start worrying about
any issues with overflow. So this should help in many cases.
And the loss of 8 bits of sub-pixel precision shouldn't cause
any harm at all---16 was really much more than necessary.
With this change the details of rasterization for several tests
are changed slightly, (particularly on arcs, for example), so
many reference images are updated here.
NOTE: This change is currently breaking get-path-extents for
ps/pdf/svg as well as push-group for ps. We do not yet know
the reasons for these new failures.
We update the test suite reference images where needed, (pdiff
avoided a few, but most still needed updating). We take advantage
of the need for new reference images to shrink some of the giant
tests to speed them up a bit.
This optimization provides a 2x improvement in linear gradient
generation performance (numbers from an x86 laptop):
image-rgb paint_linear_rgba_source-512 26.13 -> 11.13: 2.35x speedup
█▍
image-rgb paint_linear_rgba_source-256 6.47 -> 2.76: 2.34x speedup
█▍
image-rgba paint_linear_rgb_over-256 6.51 -> 2.86: 2.28x speedup
█▎
image-rgb paint_linear_rgba_over-512 28.62 -> 13.70: 2.09x speedup
█▏
image-rgba fill_linear_rgb_over-256 3.24 -> 1.94: 1.66x speedup
▋
image-rgb stroke_linear_rgba_over-256 5.68 -> 4.10: 1.39x speedup
▍
The previous change was in b62710d4f8
We just forgot to update the reference images at the time so there
have been false failure results in the test suite until now.
The commit that introduced this change is:
commit b104a79502
Author: Bertram Felgenhauer <int-e@gmx.de>
Date: Tue Jun 13 20:07:28 2006 -0400
Patch to fix pixman samping location bug (#2488).
Throw away old gradient code from within cairo-pattern.c in favor of using new support in pixman for gradients.
Update reference images for all tests involving gradients since the gradient output has changed slightly.
Replace cairo cache implementation (this code from cworth)
No more global glyph cache to clean up
Store glyphs in new per-scaled font caches which hold user-space metrics and device space bounding boxes
Refactor glyph drawing APIs so that the surface API is invoked directly from the gstate code.
Add path creation/destruction routines (to hold glyph paths)
New implementation of scaled fonts which uses per-scaled_font caches for glyphs and keeps user-space metrics, device-space bboxes along with glyph images and/or glyph paths.
Adapt to new scaled font API changes.
New cache and scaled_font APIs
Repond to bug fix in metrics computation for glyphs where y values were rounded up instead of down because of a sign difference between cairo and FreeType.
Reviewed by: otaylor, cworth
Use pointer comparison for coincident points to ensure a well-defined ordering, and avoid setting discard on both points. This fixes problems with my Mac's implementation of qsort. Final patch by Bertram Felgenhauer.
Update reference images after the change.
CLEAR and SOURCE are now bounded.
Assert that SOURCE and CLEAR aren't passed to these functions.
Assert that SOURCE and CLEAR aren't passed to these functions when there is a mask.
Do fixups for SOURCE and CLEAR as well as unbounded operators, since in the absence of a mask, we need SOURCE to work correctly (don't care about CLEAR)
_cairo_ft_font_show_glyphs) Consistently use CLEAR/TRANSPARENT (source doesn't matter) rather than SOURCE/TRANSPARENT when clearing rectangles.
src/cairo-xlib-surface.c src/cairo-surface.c: Use IN rather than SOURCE as an example of an unbounded operator in docs.
Remove CLEAR/SOURCE columns since they are no longer unbounded.
test/operator-clear.c test/operator-source Makefile.am: Add targetted tests of CLEAR/SOURCE.
