If creation fails, create an offscreen image instead and draw that as a
texture.
Because offscreens basically always succeed, we can pretty much assume
success everywhere - apart from pattern creation functions that also
create images, because they can run out of shader space.
Frames now carry a timestamp for when they are used.
This is mainly intended to attach timestamps to cached items (textures
or glyphs), but it could in theory also be used when profiling.
We use wallclock time here, not server time, because it's cheaper and
because we're more intereseted in the local machine we're rendering on.
Now we can extend the pattern creation easily - and we can add new
patterns quickly later.
Plus, we need to keep this file in sync with pattern.glsl and it's neat
when those 2 files reference only each other.
Because GL flips its shit sometimes (ie when it's the framebuffer),
pass the height of the target as the flip variable, so commands
that need to operate on the pixels can flip the y axis around this value.
This is again mostly a copy of the Vulkan renderer.
It's a bit awkward codewise with the new invalidation framework,
because we need to cache the previous values individually now,
but it's a lot more finegrained, and we don't emit globals multiple
times when clips are nested.
... and use it to initialize the "proper" projection matrix to use in
shaders.
The resulting viewport will go from top left (0,0) to bottom right
(width, height) and the z clipping plane will go from -10000 to 10000.
This heaves over an inital chunk of code from the Vulkan renderer to
execute shaders.
The only shader that exists for now is a shader that draws a single
texture.
We use that to replace the blit op we were doing before.
For now, it just renders using cairo, uploads the result to the GPU,
blits it onto the framebuffer and then is happy.
But it can do that using Vulkan and using GL (no idea which version).
The most important thing still missing is shaders.
It also has a bunch of copy/paste from the Vulkan renderer that isn't
used yet.
But I didn't want to rip it out and then try to copy it back later
We want to introduce a new one next.
Technically, this breaks API, because gsk_vulkan_renderer_new() is going
away, but practically, we're gonna bring it back once we introduce that
renderer in a few commits.
These are not usable outside of GTK, so lets not burden bindings
with them.
I'll keep the get_child() function exposed, since it is needed to
iterate over node trees containing subsurface nodes.
asan randomly failed when this almost correct code wasn't quite correct.
Hopefully this is the correct incantation to compute the size.
Related: glib#205
This is mostly untested and a result of reading the code.
The main effect here happens when a node was drawn that didn't start on
an integer boundary, which is very rare.
However, with specially crafted tests and when using fractional scaling,
this can happen.
This happened most often when clipping by the node bounds to restrict a
push_group() call. Enlarge that rectangle to fall on a pixel boundary.
Testcase included
The code was writing invalid memory, so this might not have always
crashed, but I did my best to write the test so it causes a SEGV.
Also included is a fix for the testsuite where the expected result was
wrong.
These 2 rectangles used to intersect fine:
0 0 50 50 / 50 0
0 0 50 50 / 0 50
But the computed result was:
0 0 50 50 / 50
which is not a valid rectangle, because the corners overlap.
Make sure such rectangles return NOT_REPRESENTABLE.
The above rectangle has been added to the testsuite.
