The first iteration of COW snapshotting always made an initial copy when
the snapshot was requested (and reused that copy until the surface was
modified). However, in a few circumstances we can avoid even that copy
so long as the surface is still alive and unmodified between the
snapshotting and its use. In order to do so, we need a new proxy surface
that can automatically perform the copy if the target should disappear
prior to use.
A subsurface is a region of another surface that may be used either to
restrict the writable area of a context or the readable extents of a
source. Whilst writing, access to the exterior of the subsurface is
prevented via clipping and when used as a source reads from the exterior
of the subsurface are governed via the extend mechanism of the pattern.
This is a simplified version of the wrapping surface where the target
surface is just a subsurface onto which we wish to draw the current
operation. In particular this is useful for the subsurface API as well
as fallbacks.
As a simple step to ensure that we do not inadvertently modify (or at least
generate compiler warns if we try) user data, mark the incoming style
and matrices as constant.
This test does various operations with a clear source surface with
various content types.
The idea is to make sure optimizations done when surface->is_clear ==
TRUE only happen in the proper cases.
By implicitly reference the target of the context instead, i.e.
this reduces the use of:
/target get (example.png) write-to-png pop
as a common idiom where the context is kept on the stack and the surface
forgotten.
Real applications that control their Drawable externally to Cairo are
'disadvantaged' by cairo-perf-trace when it creates a similar surface
for each new instance of the same Drawable. The difficulty in
maintaining one perf surface for every application surface is that the
traces do not track lifetimes for the application surfaces, so we would
just accumulate stale surfaces. The surface cache takes a different
approach and returns the same surface for each active Drawable, and
maintains a hold-over of the MRU 16 surfaces. This achieves 60-80% hit
rate with firefox, which is probably as good as can be expected.
Obviously for double-buffered applications we only every draw to freshly
created surfaces (and Gtk+ bypasses cairo to do the final copy -- the
ideal application would just use a push-group for double buffering, in
which case we would capture and replay the entire expose event).
To enable use of the surface cache whilst replaying use -c:
./cairo-perf-trace -c firefox-talos-gfx
An older variant of the fixes for moving the device transformation out
of the surface layer, but languished in a side branch. The only benefit
of this patch is that it avoids the copy where possible.
When the texture is GL_RGB, GL_CLAMP_TO_BORDER (EXTEND_NONE) fills the
border color alpha channel with 1, when the whole reason we were using
the border color was to get a color and alpha of 0. We're forced to
use GL_RGBA textures and do extra work to fill in the alpha channel of
them to 1 to get cairo's desired behavior.
This fixes a failure in rotate-image-surface-paint and 4 other
testcases. No performance difference in firefox-talos-gfx.
Hanno Meyer-Thurow reported in
http://bugs.freedesktop.org/show_bug.cgi?id=26063
[PATCH] various fixes to cairo-qt
a few issues related to _cairo_qt_surface_flush() where firefox was
crashing after being built to use cairo-qt.
This is an amalgam of those patches that hopefully address the issue.
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.
Jeff reported a regression found by Mozilla whereby a uniform gradient
was not being premultiplied on conversion to a solid pattern.
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.
Quartz doesn't try to approximate dash pattern even if they are well
beyond suface sampling frequency. Approximating dash patterns when their
density is too high avoids looping indefinitely in these degenerate cases.
Ultimately, we want all of our paths to use shaders when they are
exposed -- it brings us closer to GL 3.0 compatibility and it should
reduce the work that GL drivers have to do per operation to compute
the required hardware state.
The whole point of making the mask was to avoid overwriting one glyph
with the data from another. Whoops.
Fixes ft-show-glyphs-positioning, text-rotate, overlapping-glyphs,
clip-text.
Failing to do so meant that we might not re-bind the framebuffer to
the correct one if we didn't follow up surface creation with drawing
to it.
Fixes many testcases. Thanks to T. Zachary Laine for tracking down
that the current_target was the source of these issues.
Normally is_clear is cleared by the caller of one of the 5 basic
entrypoints, but in this temporary surface usage nobody else can do it
for us.
Fixes ft-show-glyphs-table, user-font-rescale, and select-font-face.
Bug 26010 - cairo_line_to optimizes away path segments
http://bugs.freedesktop.org/show_bug.cgi?id=26010
As exercised by path-stroke-twice, we incorrectly optimise away a line
segment if the path doubled back upon itself. This is very reminiscent
of the optimisation bug for replacing curve-to with line-to.
mpsuzuki spotted that the output stream for the subset was not being
destroyed on the error path - on closer inspection, it wasn't destroyed
along the normal path either and may never have been correctly
initialised to NULL on an earlier error.
Reported-by: mpsuzuki@hiroshima-u.ac.jp
The number of points in a triangle fan was miscomputed because
it was computing the number of line segments rather than points
in the fan. Now we include the final point of the fan correctly
in the count.
This fixes https://bugs.webkit.org/show_bug.cgi?id=33071 as
reported by Benjamin Otte. A derived test case was not added
to the cairo test suite since the bug is difficult to trigger in
a reliable way which causes visible results (as opposed to
silent heap corruption.)
The easiest way of triggering the bug is to stroke a line
using a large line width and round caps or joins.
We have a test case get-and-set which wants to see whatever it puts
into a cairo_t come back out again, but at the same time cairo-gstate
wants to range reduce the dash offset it's given to a sane range.
This patch changes the range reduction algorithm to always normalize
to a non-negative dash offset and not touch dash offsets which are
already in range.
