This adds a new GPU accelerated backend for Cairo based on the Cogl 3D
graphics API.
This backend aims to support Cairo in a way that translates as naturally
as possible to using a GPU, it does not strive to compete with the
anti-aliasing quality of the image backend if it can't be done
efficiently using the GPU - raw performance isn't the only metric of
concern, so is power usage.
As an overview of how the backend works:
- fills are handled by tessellating paths into triangles
- the backend has an extra fill_rectangle drawing operation so we have
a fast-path for drawing rectangles which are so common.
- strokes are also tessellated into triangles.
- stroke and fill tessellations are cached to avoid the cpu overhead
of tessellation and cost of upload given that its common for apps to
re-draw the same path multiple times. The tessellations can survive
translations and rotations increasing the probability that they can be
re-used.
- sources and masks are handled using multi-texturing.
- clipping is handled with a scissor and the stencil buffer which
we're careful to only update when they really change.
- linear gradients are rendered to a 1d texture using a triangle
strip + interpolating color attributes. All cairo extend modes
are handled by corresponding texture sampler wrap modes without
needing programmable fragment processing.
- antialiasing should be handled using Cogl's multisampling API
XXX: This is a work in progress!!
TODO:
- handle at least basic radial gradients (No need to handle full
pdf semantics, since css, svg and canvas only allow radial gradients
defined as one circle + a point that must lie within the first
circle.) - currently we fall back to pixman for radial gradients.
- support glyph rendering with a decent glyph cache design. The
current plan is a per scaled-font growable cache texture + a
scratch cache for one-shot/short-lived glyphs.
- decide how to handle npot textures when lacking hardware support.
Current plan is to add a transparent border to npot textures and use
CLAMP_TO_EDGE for the default EXTEND_NONE semantics. For anything else
we can allocate a shadow npot texture and scale the original to fit
that so we can map extend modes to texture sampler modes.
Originally written by Vladimir Vukicevic to investigate using Skia for
Mozilla, it provides a nice integration with a rather interesting code
base. By hooking Skia underneath Cairo it allows us to directly compare
code paths... which is interesting.
[updated by Chris Wilson]
Use the DRM interface to h/w accelerate composition on image surfaces.
The purpose of the backend is simply to explore what such a hardware
interface might look like and what benefits we might expect. The
use case that might justify writing such custom backends are embedded
devices running a drm compositor like wayland - which would, for example,
allow one to write applications that seamlessly integrated accelerated,
dynamic, high quality 2D graphics using Cairo with advanced interaction
(e.g. smooth animations in the UI) driven by a clutter framework...
In this first step we introduce the fundamental wrapping of GEM for intel
and radeon chipsets, and, for comparison, gallium. No acceleration, all
we do is use buffer objects (that is use the kernel memory manager) to
allocate images and simply use the fallback mechanism. This provides a
suitable base to start writing chip specific drivers.
Based on the work by Øyvind Kolås and Pierre Tardy -- many thanks to
Pierre for pushing this backend for inclusion as well as testing and
reviewing my initial patch. And many more thanks to pippin for writing the
backend in the first place!
Hacked and chopped by myself into a suitable basis for a backend. Quite a
few issues remain open, but would seem to be ready for testing on suitable
hardware.
By moving the backend target definition out of the massive amlagamated
block in cairo-boilerplate.c and into each of the
cairo-boilerplate-backend.c, we make it much easier to add new targets as
the information need only be entered in a single file and not scattered
across three. However, updating the target interface means trawling across
all the files -- except given that I found it difficult maintaining the
single massive array I do not see this as an increase in the maintenance
burden.
Written by Vladimir Vukicevic to enable integration with Qt embedded
devices, this backend allows cairo code to target QPainter, and use
it as a source for other cairo backends.
This imports the sources from mozilla-central:
http://mxr.mozilla.org/mozilla-central/find?text=&kind=text&string=cairo-qpainter
renames them from cairo-qpainter to cairo-qt, and integrates the patch
by Oleg Romashin:
https://bugs.freedesktop.org/attachment.cgi?id=18953
And then attempts to restore 'make check' to full functionality.
However:
- C++ does not play well with the PLT symbol hiding, and leaks into the
global namespace. 'make check' fails at check-plt.sh
- Qt embeds a GUI into QApplication which it requires to construct any
QPainter drawable, i.e. used by the boilerplate to create a cairo-qt
surface, and this leaks fonts (cairo-ft-fonts no less) causing assertion
failures that all cairo objects are accounted for upon destruction.
[Updated by Chris Wilson]
Acked-by: Jeff Muizelaar <jeff@infidigm.net>
Acked-by: Carl Worth <cworth@cworth.org>
Felt like pulling the latest stuff, since I branched back in February.
Conflicts:
build/configure.ac.features
src/cairo.h
util/cairo-script/csi-replay.c
As suggested on the list, this splits the cairo-boilerplate-glitz.c
file in three separate files, one for each backend. Furthermore,
it fixes a few problems in compilation of the AGL backend test harness.
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.)
