Hopefully reduce the occurrence of the confusion between the
premultiplied shorts in cairo_color_t and the non-premultiplied shorts
in cairo_color_stop_t.
The existence of the two separate types is debatable and open for
review.
color stops are not premultiplied so we need to handle them carefully
when comparing. The next step will be to make cairo_color_stop_t a
unique type to prevent this mistake again.
In order to reuse the original image as the pixman pattern, then the
entire operation must be wholly contained within the extents of the
image (including subsurfaces) and be reducible to an untransformed
REPEAT_NONE.
_gradient_is_opaque() previously returned TRUE for gradient with
no stops, triggering a false optimization in _cairo_gstate_mask().
Fixes test/gradient-zero-stops-mask
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Still an experimental backend, it's now a little too late to stabilise
for 1.10, but this should represent a major step forward in its feature
set and an attempt to catch up with all the bug fixes that have been
performed on xlib. Notably not tested yet (and expected to be broken)
are mixed-endian connections and low bitdepth servers (the dithering
support has not been copied over for instance). However, it seems robust
enough for daily use...
Of particular note in this update is that the xcb surface is now capable
of subverting the xlib surface through the ./configure --enable-xlib-xcb
option. This replaces the xlib surface with a proxy that forwards all
operations to an equivalent xcb surface whilst preserving the cairo-xlib
API that is required for compatibility with the existing applications,
for instance GTK+ and Mozilla. Also you can experiment with enabling a
DRM bypass, though you need to be extremely foolhardy to do so.
By preallocating in our data segment a couple of solid patterns for the
stock colours, it becomes more convenient when using those in surface
operations, such as when clearing.
Fixes: test/linear-uniform
https://bugzilla.mozilla.org/show_bug.cgi?id=539165
Bug 539165 - gradients with a single stop do not have their color
multiplied by the alpha.
As reported by Jeff Muizelaar, we regressed in 2d790daa as the
color-stops are not premultiplied and so could not be treated as an
ordinary cairo_color_t. Instead we have to create a intermediate
cairo_color_t from the original values in order for the
premultiplication to be performed.
If the pattern is for example a repeating 0x0 image, then treat it as
having zero extents.
This should workaround the bug presented here:
https://bugs.freedesktop.org/show_bug.cgi?id=24693
Attached PDF crashes evince with a Floating point exception
Within our code base we carried a few hacks to utilize the component
alpha capabilities of pixman, whilst not supporting the concept for our
own masks. Thus we were setting it upon the pixman_image_t that we
passed around through code that was blissfully unaware and indeed the
component-alpha property was forgotten (e.g. upgrading glyph masks).
The real issue is that without explicit support that a pattern carries
subpixel masking information, that information is lost when using that
pattern with composite. Again we can look at the example of compositing
a sub-pixel glyph mask onto a remote xlib surface for further failure.
Gah, that was a horrible mistake. It was a flawed hack to create Pixmaps
of the correct depth when cloning patterns for blitting to the xlib
backend. However, it had the nasty side-effect of discarding alpha when
targeting Window surfaces. The correct solution is to simply correct the
Pixmap of the desired depth and render a matching pattern onto the
surface - i.e. a reversal the current acquire -> clone. See the
forthcoming revised xcb backend on how I should have done it originally.
As noted in the comments we could also compute the pattern extents for
gradients with CAIRO_EXTEND_NONE under certain circumstances, i.e.
radial gradients and device axis aligned linear gradients.
Previously the pattern_acquire_surface routine only had to worry about
handling extend modes NONE or REPEAT and so the test for ! REPEAT
sufficed when what was actually intended was a test for NONE.
Handling clip as part of the surface state, as opposed to being part of
the operation state, is cumbersome and a hindrance to providing true proxy
surface support. For example, the clip must be copied from the surface
onto the fallback image, but this was forgotten causing undue hassle in
each backend. Another example is the contortion the meta surface
endures to ensure the clip is correctly recorded. By contrast passing the
clip along with the operation is quite simple and enables us to write
generic handlers for providing surface wrappers. (And in the future, we
should be able to write more esoteric wrappers, e.g. automatic 2x FSAA,
trivially.)
In brief, instead of the surface automatically applying the clip before
calling the backend, the backend can call into a generic helper to apply
clipping. For raster surfaces, clip regions are handled automatically as
part of the composite interface. For vector surfaces, a clip helper is
introduced to replay and callback into an intersect_clip_path() function
as necessary.
Whilst this is not primarily a performance related change (the change
should just move the computation of the clip from the moment it is applied
by the user to the moment it is required by the backend), it is important
to track any potential regression:
ppc:
Speedups
========
image-rgba evolution-20090607-0 1026085.22 0.18% -> 672972.07 0.77%: 1.52x speedup
▌
image-rgba evolution-20090618-0 680579.98 0.12% -> 573237.66 0.16%: 1.19x speedup
▎
image-rgba swfdec-fill-rate-4xaa-0 460296.92 0.36% -> 407464.63 0.42%: 1.13x speedup
▏
image-rgba swfdec-fill-rate-2xaa-0 128431.95 0.47% -> 115051.86 0.42%: 1.12x speedup
▏
Slowdowns
=========
image-rgba firefox-periodic-table-0 56837.61 0.78% -> 66055.17 3.20%: 1.09x slowdown
▏
Observe that patterns are not altered during an operation and so we are
safe to use the data from the original pattern without copying. (This is
enforced through the declaration that the backends operate on constant
patterns which are not allowed to be referenced or destroyed.)
Allow the caller to choose whether or not various conversions take place.
The first flag is used to disable the expansion of reflected patterns into a
repeating surface.
Some backends are quite constrained with surface sizes and so trigger
fallbacks when asked to clone large images. To avoid this we attempt
to trim ROIs (as these are often limited to the destination image, and
so can be accommodated by the hardware). This patch allows trimming
REPEAT sources both horizontally and vertically independently.
As an aide to tracking down the source of uninitialised reads, run
VALGRIND_CHECK_MEM_IS_DEFINED() over the contents of image surfaces at the
boundary between backends, e.g. upon setting a glyph image or acquiring
a source image.
Damian Frank noted
[http://lists.cairographics.org/archives/cairo/2009-May/017095.html]
a performance problem with an older XServer with an
unaccelerated composite - similar problems will be seen with non-XRender
servers which will trigger extraneous fallbacks. The problem he found was
that painting an ARGB32 image onto an RGB24 destination window (using
SOURCE) was going via the RENDER protocol and not core. He was able to
demonstrate that this could be worked around by declaring the pixel data as
an RGB24 image. The issue is that the image is uploaded into a temporary
pixmap of matching depth (i.e. 32 bit for ARGB32 and 24 bit for RGB23
data), however the core protocol can only blit between Drawables of
matching depth - so without the work-around the Drawables are mismatched
and we either need to use RENDER or fallback.
This patch adds a content mask to _cairo_surface_clone_similar() to
provide the extra bit of information to the backends for when it is
possible for them to drop channels from the clone. This is used by the
xlib backend to only create a 24 bit source when blitting to a Window.
Ensure that no assumptions are made that a small allocation will succeed
by manually injecting faults when we may be simply allocating from an
embedded memory pool.
The main advantage in manual fault injection is improved code coverage -
from within the test suite most allocations are handled by the embedded
memory pools.
Assert that the pattern is one of the four known types, and return an
error so that the compiler knows that the local variable can not be used
uninitialised.
A new meta-surface backend for serialising drawing operations to a
CairoScript file. The principal use (as currently envisaged) is to provide
a round-trip testing mechanism for CairoScript - i.e. we can generate
script files for every test in the suite and check that we can replay them
with perfect fidelity. (Obviously this does not provide complete coverage
of CairoScript's syntax, but should give reasonable coverage over the
operators.)
