During the copy, allocation of the gradient may fail and so the callers
need to check for a pattern that returned in an error state. No callers
did so and in order to force all callers to check the error status,
the status return was added to _cairo_pattern_init_copy(). The early
error checking may appear redundant for an object with an embedded
structure, however it does fix an error where an uninitialised pattern
was being used:
==1922== Process terminating with default action of signal 11 (SIGSEGV)
==1922== Access not within mapped region at address 0x55555555
==1922== at 0x402CF6F: _cairo_array_index (cairo-array.c:208)
==1922== by 0x402D4F3: _cairo_user_data_array_fini (cairo-array.c:370)
==1922== by 0x4046464: _cairo_pattern_fini (cairo-pattern.c:188)
==1922== by 0x404992A: _cairo_meta_surface_paint (cairo-meta-surface.c:266)
==1922== by 0x403FCE0: _cairo_surface_paint (cairo-surface.c:1331)
==1922== by 0x405CB5E: _test_meta_surface_paint (test-meta-surface.c:195)
==1922== by 0x403FCE0: _cairo_surface_paint (cairo-surface.c:1331)
==1922== by 0x4032A60: _cairo_gstate_paint (cairo-gstate.c:822)
==1922== by 0x402B2D1: cairo_paint (cairo.c:1879)
==1922== by 0x804A4F7: draw (radial-gradient.c:73)
==1922== by 0x804AFA4: cairo_test_expecting (cairo-test.c:326)
==1922== by 0x804A57C: main (radial-gradient.c:109)
==1922== Injected fault at:
==1922== at 0x4020EA5: malloc (vg_replace_malloc.c:207)
==1922== by 0x404475C: _cairo_pattern_init_copy (cairo-pattern.c:136)
==1922== by 0x403F779: _cairo_surface_copy_pattern_for_destination (cairo-surface.c:2153)
==1922== by 0x403FCC1: _cairo_surface_paint (cairo-surface.c:1328)
==1922== by 0x405CB5E: _test_meta_surface_paint (test-meta-surface.c:195)
==1922== by 0x403FCE0: _cairo_surface_paint (cairo-surface.c:1331)
==1922== by 0x4032A60: _cairo_gstate_paint (cairo-gstate.c:822)
==1922== by 0x402B2D1: cairo_paint (cairo.c:1879)
==1922== by 0x804A4F7: draw (radial-gradient.c:73)
==1922== by 0x804AFA4: cairo_test_expecting (cairo-test.c:326)
==1922== by 0x804A57C: main (radial-gradient.c:109)
The design is for the user to create a cairo_font_options_t object with
cairo_font_options_create() and then is free to use it with any Cairo
operation. This requires us to check when we may be about to overwrite
the read-only nil object.
Simply return without writing to potentially read-only members of an
invalid pattern rather than assert. This is cleaner than tracking down
all the error paths that may call into cairo_pattern_transform()...
Check for an allocation failure during _cairo_analysis_surface_create()
and propagate to caller - where we discover that the callers themselves
missed the status checks...
_cairo_surface_create_similar_solid() may return an image surface,
should the backend not support the required content or should it
encounter an error whilst creating the surface. In those circumstances
we choose not to cache the fallback surface.
Original work by Jorn Baayen <jorn@openedhand.com>,
2715f20981
We use a small cache of size 16 for surfaces created for solid patterns.
This mainly helps with the X backends where we don't have to create a
pattern for every operation, so we save a lot on X traffic. Xft uses a
similar cache, so cairo's text rendering traffic with the xlib backend
now completely matches that of Xft.
The cache uses an static index variable, which itself acts like a cache of
size 1, remembering the most recently used solid pattern. So repeated
lookups for the same pattern hit immediately. If that fails, the cache is
searched linearly, and if that fails too, a new surface is created and a
random member of the cache is evicted.
A cached surface can only be reused if it is similar to the destination.
In order to check for similar surfaces a new test is introduced for the
backends to determine that the cached surface is as would be returned by
a _create_similar() call for the destination and content.
As surfaces are in general complex encapsulation of graphics state we
only return unshared cached surfaces and reset them (to clear any error
conditions and graphics state). In practice this makes little difference
to the efficacy of the cache during various benchmarks. However, in order
to transparently share solid surfaces it would be possible to implement a
COW scheme.
Cache hit rates: (hit same index + hit in cache) / lookups
cairo-perf: (42346 + 28480) / 159600 = 44.38%
gtk-theme-torturer: (3023 + 3502) / 6528 = 99.95%
gtk-perf: (8270 + 3190) / 21504 = 53.29%
This translates into a reduction of about 25% of the XRENDER traffic during
cairo-perf.
By deferring the issuing of the X requests to set the clip mask we can
theoretically avoid some redundant requests, but primarily we remove
another path where X requests are emitted.
Due to caching, destruction of X11 resources may occur outside of a
usable X11 context. To avoid this, we defer the destruction onto a work
queue which will be run the next time we try to use the X11 connection
on behalf of the user (at which point we must have a usable X11 context!)
or we are closing the Display.
Due to the nature of the reference counting, an X resource may be
destroyed later than anticipated and possibly from a different thread
than the original context. This becomes an issue for applications that
carefully manage their single X connection from a single thread and do
not use locking and are then suprised when cairo triggers X traffic when
performing work for a different part of the application in another thread.
Previously, we stored the per-display attributes inside a special
screen=NULL _cairo_xlib_screen_info_t. Now we keep track of known X
displays and store the screen information beneath the display structure
alongside the per-display hooks.
_cairo_pattern_acquire_surfaces() may substitute an image surface for
either the source or the mask should the backend not support creation
of similar scratch surfaces or an error occurs during creation. For
composition we require xlib surfaces and so we must trigger the
fallback path if this happens.
as now the mutex layer will define a generic CAIRO_MUTEX_FINALIZE()
whenever the implementation defines CAIRO_MUTEX_FINI(). In the
case of pthread however we don't need finalization as we don't
have any place to call it, and pthread_mutex_destroy() doesn't
do much anyway.
Previously cairo-mutex.c was abusing cairo-mutex-private.h by
defining CAIRO_MUTEX_DECLARE before including it, and
cairo-mutex-private.h was simply not overriding any available
CAIRO_MUTEX_DECLARE. This is not the way it should be.
cairo-mutex.c should instead define CAIRO_MUTEX_DECLARE and
include cairo-mutex-list-private.h for itself.
If we create the Pixmap whilst constructing a similar xlib surface, then
it our responsibility to free the Pixmap should we fail to allocate the
surface.
This fixes the problem reported by Dave Yeo that boilerplate wasn't building:
In file included from ../src/cairo-scaled-font-private.h:44,
from cairo-boilerplate.c:65:
../src/cairo-mutex-private.h:183: error: syntax error before "extern"
../src/cairo-mutex-private.h:184: error: syntax error before "void"
../src/cairo-mutex-private.h:185: error: syntax error before "void"
make[3]: *** [cairo-boilerplate.lo] Error 1
The WINVER macros need to be defined before including <windows.h>.
As a result of some recent include file rearranging, <windows.h>
was included indirectly before WINVER was defined.
It's quite simple to add a new _cairo_traps_limit call which installs
a box into the cairo_traps_t structure. Then at the time of
_cairo_traps_add we can discard any trapezoid that is wholly outside
the box and also clip any trapezoid that is partially outside the box.
We take advantage of this for both cairo_stroke and cairo_fill, (when
cairo is computing the trapezoids in cairo-surface-fallback.c). Note
that we explicitly do not do any clipping for cairo_stroke_extents,
cairo_fill_extents, cairo_in_stroke, or cairo_in_fill which are
defined to ignore clipping.
As seen by the long-lines perf case, this fix successfully works
around the bug in the X server where it creates overly large masks for
partially-outside-the-destination-surface trapezoids:
xlib-rgba long-lines-uncropped-100 545.84 -> 5.83: 93.09x speedup
██████████████████████████████████████████████
xlib-rgb long-lines-uncropped-100 554.74 -> 8.10: 69.04x speedup
██████████████████████████████████
Some PDF viewers forget the CTM when drawing gradient patterns
with SMasks. This patch works around these bugs by using the default
identity matrix for the CTM. All paths are transformed from
cairo to pdf coordinates before writing to the pdf file.
This allows for the surface acquired from the pattern to have the
same content. In particular, in a case such as cairo_paint_with_alpha
we can now acquire an A8 mask surface instead of an ARGB32 mask
surface which can be rendered much more efficiently. This results
in a 4x speedup when using the OVER operator with the recently
added paint-with-alpha test:
Speedups
========
image-rgb paint-with-alpha_image_rgb_over-256 2.25 -> 0.60: 4.45x speedup
███▌
It does slowdown the same test when using the SOURCE operator, but
I don't think we care. Performing SOURCE with a mask is already a very
slow operation, (hitting compositeGeneral), so the slowdown here is
likely from having to convert from A8 back to ARGB32 before the
generalized compositing. So if someone cares about this slowdown,
(though SOURCE with cairo_paint_with_alpha doesn't seem extremely
useful), they will probably be motivated enough to contribute a
customized compositing function to replace compositeGeneral in which
case this slowdown should go away:
image-rgba paint-with-alpha_image_rgb_source-256 3.84 -> 8.86%: 1.94x slowdown
█
With the introduction of the error callbacks for PNG, we have the
opportunity for the user to set a breakpoint (via _cairo_error) at the
point the error is first rasied.
