Whilst investigating:
Bug 31788: SVG <line> with y1 == y2 and both with fractional
part don't render
https://bugs.webkit.org/show_bug.cgi?id=31788
I found that it can be reduced to a no-op clip following a no-op stroke
or fill. These conditions are exercised here and are shown to be a bug
introduced in the 1.9.x development series.
Add some auxiliary functions to cairo-stroke-style to compute
properties of the dashed patterns (period, "on" coverage) and to
generate approximations when the dash pattern is sub-tolerance.
These functions are used in cairo-path-stroke to simplify dash
patterns stroked by cairo.
Fixes dash-infinite-loop
See http://bugs.freedesktop.org/show_bug.cgi?id=24702
The infinite loop problem in _cairo_stroker_dash_start is solved by
commit ee02f3484899527380df94c00f40da87f41660ea, so hitting that
problem is not possible anymore and dash-infinite stroke always
hit the memory intensive loops.
This reverts commit 29432d3d32.
The stroke offset was forced to be positive because stroking code
wants to be able to decrement it until it finds the first dash to be
drawn. This can lead to long (almost infinite) loops if the offset is
positive but huge compared to the total length of the dash pattern.
Computing the offset this way guarantees that it's always the smallest
non-negative equivalent offset.
When computing an equivalent offset, a wrong total dash length was
used when the dash elements were odd and more than 1.
Doubling the total dash length whenever they are odd is needed to
correctly compute the new offset.
Fixes dash-offset.
Remove the transformation code as it's useless and confusing.
The clipbox was transformed in a wrong way if the CTM
was not the base one, otherwise the transformation did nothing.
As long as _cairo_quartz_setup_fallback_source is only called
with the base CTM, no transformation needs to be performed on the
clipbox.
Patch by Robert O'Callahan, see Mozilla bug #507939.
Fallback on SATURATE (since quartz doesn't support it) and on
blending operators (to be implemented using CGContextSetBlendMode,
after its availability has been assessed).
Workaround the different behaviour of quartz operators on alpha
masks.
Fixes text in clip-operator and clip-text, blend modes in
extended-blend, extended-blend-alpha, saturate in operator,
operator-alpha and surface-pattern-operator.
Changes the output of operator-alpha-alpha, but to really fix it
pure-alpha surfaces needs to be treated as alpha masks and not as
greyscale images.
Surface sources were not respecting EXTEND_NONE when composited
because the part outside of the surface rectangle was not changed.
To correctly extend the source, it's sufficient to composite a
transparent rectangle with a hole in the region covered by the surface.
Fixes clip-unbounded and operator-source. Changes the output of
surface-pattern-operator.
Stroking was not fixed up correctly when the stroke trasform
was not the identity and when the stroked path was dashed.
Instead of building a mask image and clearing through it
(forgetting to use the CTM and the dash setting), the code now
simply fills the outside of the stroke with tranparent black.
Additionally this commit moves the CTM composition so that the invocation
of _cairo_quartz_setup_source is always done with the base CTM.
This commit changes the result of clip-stroke-unbounded (the clip
mask is now correctly aligned to the stroked path).
A8 images were cosidered grayscale, whereas they should behave like
transparency mask. They are now alpha-only images and the stride is
16-bytes aligned, as suggested.
Fixes alpha-similar and mask-transformed-similar. Makes the patterns
behave (as expected) as masks in surface-pattern-operator.
Affects the output of operator-alpha-alpha, but the result is not
correct because of wrong compositing.
CTM was changed and not restored when painting gradients.
Fixes the alignment of surface patterns in surface-pattern-operator.
Patch by Robert O'Callahan, see Mozilla bug #507939.
Enable "ld_preload" (DYLD_INSERT_LIBRARIES + DYLD_FORCE_FLAT_NAMESPACE)
and build cairo-trace as a library instead of a module to make it
work also on MacOS X.
Compositing of alpha-only sources is not throughly tested and
as a consequence the misbehaviour of some backends is not
shown by the test suite.
[ickle: Added XFAILs for pdf, ps, svg.]
Type 1 fonts embedded in PDF have the the encrypted portion in binary
but the existing check for binary only works for Type 1 fonts in PFB
format.
Add an additional check based on the first 4 characters of eexec data.
The Type 1 specification gurantees that at least one of the first 4
bytes of ciphertext is not an ASCII Hex character.
At the end of the private dictionary a new line is appended so that
the trailing zeros will not exceed 80 columns. In hex mode (used for
PS embedding) extra white space is harmless as it is ignored when
parsing the ascii hex encoded data. But in binary mode (used for PDF
embedding) the new line must not be added as it corrupts the binary
data.
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/419143
Both _cairo_xlib_call_close_display_hooks and _cairo_xlib_screen_destroy
invoke _cairo_xlib_screen_close_display, which frees all the cached
GCs, but (if HAS_ATOMIC_OPS is undefined) doesn't mark them as freed,
thus freeing them agin upon the second invocation.
The function _cairo_image_surface_create_for_content does not exist.
The correct name of the function is instead _cairo_image_surface_create_with_content.
When the reference point was tirggering _line_exceeds_16_16() and got
adjusted, the code failed to compute the srcX and srcY arguments for the
call to XRenderCompositeTrapezoids() correctly and caused the resulting
source image to be misaligned.
This test fills a slightly rotated surface slightly above the 0 line.
This hits some corner cases in the XRenderComposite path.
I discovered these issues while playing with video rendering onto the
canvas in HTML5 (both Webkit and Mozilla have this problem).
I used CAIRO_ANTIALIAS_NONE and a single-color source in the test to get
rid of aliasing issues in the output images. This makes some issues
slightly less visible, but still fails for all of them. If you want to
get a clearer view, disable it and use romedalen.png instead - it has
the same size as the red surface.
(At least) 3 bugs are at work here:
- if _line_exceeds_16_16() triggers for the reference point, the
source surface will be misaligned.
- the intel driver seems to have an off-by-one bug on my i945 when
positioning the source surface, causing black seams at the top
(not visible in the test unless using romedalen.png) and on the left
of the image.
- My Xvfb fails completely in picture up/download in the xlib-fallback
path.
Only the very first line-to following a move-to can have any
significance if degenerate whilst stroking, so skip all others.
In other words,
0 0 m 0 0 l stroke
produces a capped degenerate path (i.e a dot),
0 0 m 0 0 l 0 0 l stroke
produces the same degenerate stroke, and
0 0 m 0 0 l 1 0 l stroke
produce a horizontal line.
Malte Nuhn reported hitting an assertion:
cairo-path-stroke.c:1816: _cairo_rectilinear_stroker_line_to: Assertion `a->x == b->x || a->y == b->y' failed.
http://bugs.freedesktop.org/show_bug.cgi?id=24797
when stroking an apparently simple path:
0 8.626485 m
0 8.626485 l
5.208333 2.5 l
10.416667 2.5 l
15.625 2.5 l
20.833333 2.5 l
26.041667 2.5 l
31.25 2.5 l
36.458333 2.5 l
41.666667 2.5 l
46.875 2.5 l
52.083333 2.5 l
57.291667 2.5 l
62.5 2.5 l
67.708333 2.5 l
72.916667 2.5 l
78.125 2.5 l
83.333333 2.5 l
88.541667 2.5 l
93.75 2.5 l
98.958333 2.5 l
104.166667 2.5 l
109.375 2.5 l
114.583333 2.5 l
119.791667 2.5 l
125 2.5 l
stroke
which upon reduction becomes:
0.000000 8.625000 m 5.207031 2.500000 l 125.000000 2.500000 l stroke
The bug is that after spotting a repeated line-to we move the previous
end-point without reclassifying the path, hence we miss the
non-rectilinear step.
Bug 24730 -- New: misleading use cases in cairo_scaled_font_text_to_glyphs's docs
http://bugs.freedesktop.org/show_bug.cgi?id=24730
An apparent copy'n'paste error from the code which has to deal with
indirect pointers crept into the documentation for the same functions.
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.
Create a scratch surface that will be initialised as required for
internal use. External surfaces, i.e. those returned to the user, are
cleared as normal.
A nasty surprise whilst profiling is that performing redundant clear
operations is extremely painful. We can mitigate this somewhat by
tracking the cleared state of surfaces and skipping repeated attempts to
clear a surface.
