The float version of many math functions were introduced in C99, and were
causing compile failure on systems like OS X. We now define them to their
double variant if __USE_ISOC99 is not defined. We may want to expand it later
to cover non-gcc compilers too, but since this is pdiff only, it's not really
important.
Previously we were defining a symbol INLINE and use that in one place, while
other places were using straight inline. With the AC_C_INLINE macro we can
just leave it to autoconf to correctly choose what inline should be defined
to.
The PS output for ft-text-vertical-layout-type3 looks correct, except for some
antialiasing mismatch. Ading ref image to fix this, and so, remove the test
from XFAIL.
We have tests for this (ft-text-vertical-*), but unfortunately they didn't
prevent the regression here because they have been marked XFAIL, since we didn't
quite fix them for PS.
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
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image-rgba paint_linear_rgb_over-256 6.51 -> 2.86: 2.28x speedup
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image-rgb paint_linear_rgba_over-512 28.62 -> 13.70: 2.09x speedup
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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
▍
I've given up on trying to preserve the old code formatting
for compatibility. We're not planning on augmenting the algorithm
itself, just integrating it into cairo. So I don't expect to
make changes that we'll be all that interested in pushing
upstream.
This is a slightly kinder interface that accepts cairo_image_surface_t
pointers rather than pointers to the raw image data and width, height,
stride. This brings us closer to hooking up the pdiff code.
In a manner similar to flattening in advance, we now extract the sub-
surface of interest (when testing with device offsets) before calling
into the buffer_diff functions. This allows these functions to accept
a single stride value once again instead of one for each of the three
images.
The old implementation was a very naive one that used to generate one XRender
glyph element per glyph. That is, position glyphs individually. This was
raised here:
http://lists.freedesktop.org/archives/cairo/2006-December/008835.html
The new implmentation is a free rewriting of the Xft logic, that is,
compressing glyphs with "natural" advance into elements, but with various
optimizations and improvements.
In short, it works like this: glyphs are looped over, skipping those that are
not desired, and computing offset from "current position". Whenever a glyph
has non-zero offsets from the current position, a new element should be
started. All these are used to compute the request size in the render
protocol. Whenever the request size may exceed the max request size, or at
the end, glyphs are flushed. For this to work, we now set non-zero glyph
advances when sending glyphs to the server.
Notable optimizations and improvements include:
- Reusing the input glyph array (with double glyph positions) as a working
array to compute glyph offsets.
- Reusing the input glyph array as the output glyph-index array to be passed
to XRender.
- Marking glyphs to be skipped as so, avoiding a copy of the glyph array,
which is what the old code was doing.
- Skip glyphs with positions "out-of-range". That is, those with positions
that would cause an overflow in Xrender's glyph offset calculations.
On my Fedora desktop on Pentium 4, and on a Nokia 770, it shows a 6% speedup on
the timetext test.
This is done in cairo_scaled_glyph_t->x/y_advance. The value is mostly useful
for raster backends, for example to set as default advance of a glyph, and
later on optimize glyph positionings that use the default advance.
