By moving negative affines to be treated like dihedrals, because they
also need support of the modelview, we can free up the affine branch for
doing work without it.
Not a big win I guess, but it makes scaling more efficient.
This allows handling them without ever needing to offscreen for losing
the clip, because the clip can always be transformed.
Also, all the optimizations keep working, like occlusion culling,
clears, and so on.
The main benefit of this work is the ability for offloading to now
handle dihedral transforms of the video buffer.
The other big advantage is that we can now start our rendering with a
dihedral transform from the compositor.
This category does a finer-grained categorization than
GskTransformCategory, but it is deliberatedly made to allow
easy backwards compatibility.
The reason for the categories is that they fit our renderers more
fine.
In particular, it allows implementing wl_output_transform support more
efficiently, thereby allowing rendering buffers the right way for
rotated phone screens or monitors.
The rectangles need to touch/overlap in both directions, otherwise
there's no coverage that covers both rectangles.
Test included.
Fixes rendering glitches in various apps when redrawing.
Fixes: #6849
... instead of init_draw(); add_node(); finish_node();
We hook into the infrastructure one step earlier and close to where the
default renderer_render() and renderer_render_texture() arrive in the
nodeprocessor.
Why is this relevant?
Because process() does occlusion culling.
TL;DR: offscreens do culling now
We import them as general, so they should be exported like that.
This was a longstanding issue that I never got around to fixing and I'm
touching this code anyway atm.
See commit 3aa6c27c26 for more details.
NULL disables clearing. We only implement this for GL as in Vulkan we'd
need to create different renderpasses with different attachment
descriptions and that would require more plumbing.
We need to check that the clip is inside the opaque region, not that the
opaque region is inside the clip.
Test included, using the only not that hits the fallback path with an
opaque region smaller than its bounds.
Sometimes container nodes contain lots of overlapping opaque items. In
that case we can use the container node itself as the first node even
though none of the children cover the whole paint area.
The use case for this is a grid of cells like in a terminal where all
the cells are opaque and we want to avoid drawing the background behind
them.
Due to the way the intermediate offscreen gets drawn, we might end up
with seams at the edges.
And I don't think it's worth spending more time on than saying "not
opaque".
Fixes the compare-render testsuite
New testcase included.
We want to operate with opacities, so it makes sense to have this radily
available.
And we're doing a walk over all children on creation anyway, so why not
just capture the rect there.
We want to be able to express opaque grids. This means that the app
provides either a row of columns of opaque nodes or a column of rows,
and then the containers will magically figure it out.
The main use case for this is terminals, which are uilt using cells. And
when there's a transparent background configured but the contents are
opaque, it'd be nice if we could figure that out.
Also remove the 80% requirement. It is rather arbitrary and while it
helps for some cases, the aforementioned grid would suffer.
Clip nodes often appear in the widget tree.
And the implementation can be trivial because of the sanity checks
already performed before calling the vfunc.
This is required because transform nodes appear everywhere.
We just exit for all transforms that can't transform the clip rect
losslessly. Both because they are rare and because we'd make the
coverage possibilities much lower.
Containers can walk the list of children back to front, trying to find
the topmost node that fully covers the viewport.
And then they can skip drawing all the nodes before that one.
Asks a node to add itself if it is fully covering the clip rectangle.
In that case, it is the first node that needs to be added.
If the node is not fully covering the clip, it should not draw itself,
because there might be stuff needing to be drawn below.
If a node adds itself, it should call gsk_gpu_render_pass_begin_op().
We find the first child that covers >80% of the container and return
that.
This is a nice speedup for the common case of a GtkWindow being covered
by a large opaque background.
It will fall apart for fancy themes that play with transparency or for
small windows because the shadow region gets too large.
But then we just scan the whole node tree.
We could think about adapting the 80% number, because that wasn't chosen
with any real scientific data behind it.
This takes both the vertical and horizontal rectangle that isn't
covering the rounded corners and intersects both with the child's opaque
rect.
And then it returns the larger of the two.
This means the small slices of a window near the left/right (or
top/bottom) will never be covered, but if we wanted that, we'd need to
use something else than a rectangle - either a region or actually a
rounded rect.
But that is a lot more expensive to implement.
We can in fact meet complex transforms here. Asserting that they
are simple doesn't make it so. Instead, simply bail out if a
transform is too complex; in this case we can't offload anyway,
so no need to walk the tree further.
Test included.
Fixes: #6824
We wanted premultiplied images in all cases anyway, and moving that
requirement means we can also move the caching code for re-caching
textures into the texture specific code.
This uses offscreens for every call to get_node_as_image().
This is useful both for benchmarking benefits of those implementations
as well as checking that the node-specific paths produce identical
results.
gsk_gpu_node_processor_ensure_image() was a weird amalgamation of stuff
withe weird required and disallowed flags.
Refactor it to make the two operations we actually do there more
explicit: Removing straight alpha and generating mipmaps.
This untangling is also desirable in the future when we also want to
handle colorstates here.
Always return premultiplied images.
2 fallback cases for clip and transform nodes did not require that. If
those cases turn out to be important, they can call
gsk_gpu_get_node_as_image() directly as that's the more flexible option.
Pass through to the child instead of offscreening.
I mainly implemented it for the assertion, because this might be a
sneaky way to introduce bugs without exhaustive checking that we don't
offload stuff that is offscreened.
No actual bugs that I'm aware of, so no tests.
Strictly defensive coding.
When getting a texture as image, we were always returning the texture
unconditionally.
However, we want to mipmap textures when the scale factor is too large,
and this code path did not do that.
The same codepath on the GL renderer doesn't do that either, so the test
is disabled for it.
The switch statement was ugly.
Plus, the code should be close to the add_node() vfunc implementation,
so they can be modified together.
See future commits for an example where this matters.
It didn't bring any noticable benefits and it isn't compatible with the
way we intend to do colorstate support.
And nobody seems to want to spend time on it, so let's get rid of it.
We can bring it back later if someone wants to work on it.
The new renderers don't support them due to the required complexity of
integrating them with Vulkan and the assumptions those nodes make about
the renderer (the GL renderer exports its internal APIs into the
GLShader).
There haven't been any complaints that I'm aware of since 4.14 was
released where the default renderer does not support the nodes, so usage
in public seems to be close to nonexistant.
The 2 uses I know of were workarounds about missing features in GTK that
have stopped since GTK now supports them:
1. GStreamer used in to do premultiplication when the old GL renderer
did not do so in hardware but on the CPU.
2. Adwaita used it for masking before the mask node wa added in 4.10.
I was watching the log in my terminal and nothing happened.
And I wasn't sure if that was because nothing was printed or because the
same thing was printed every few seconds.
Fix that by printing a timestamp, so that in a few seconds something
else will be printed.
Previously we tracked the dead pixels, but that meant we didn't know the
alive pixels (because there's also unused pixels never accounted for).
And we would free the current atlas randomly due to that.
Now we track if any pixels are alive, and if so, we never gc the current
atlas.
After 60s, we gc the atlas, too. This ensures that after that time, we
free all cache resources, so if an application gets moved to the
background, it will no longer use GPU resources. (Well, at least the
cache won't.)
Only if a non-stale item is in the cache do we consider the cache not
empty.
Once the cache is empty, the device frees it and stops running the
periodic GC.
This is for 3 reasons:
1. Separation of concerns
The device is meant to manage the Vulkan/GL device and check stuff
like image sizes.
Caching is not part of that.
2. Refcounting
Images etc want to reference the device, but the cache wants to
reference images. If the cache is the device, that's a refcycle.
3. Flexibility
It's now easier to implement >1 cache, say one per depth or one per
color state.
Keeping the GdkRGBA requires doing later conversions, which isn't
necessary if we just keep the already converted float[4].
It also prepares for future color states, where the color will need to
be converted using the colorstate.
Fill and stroke nodes were not reporting proper offscreen-for-opacity
and preferred depth.
This was unlikely to have been noticed as their child is usually a solid
color.
Despite my best effort, it seems impossible to make ci and local
builds agree on what font subsetter and fonts to use, so make this
opt-in for now: If you want to produce a node file with embedded
fonts, set GSK_SUBSET_FONTS=1.
The rendernode parser creates its own fontmap for the fonts that
we deserialize from blobs. But we were using the system fontconfig
configuration for it, leading to system fonts still being found.
This is bad, and causes test failures in ci. Try with an empty
fontconfig configuration instead.
Since GskTransform is immutable, a lot of the documented "methods" are
more like "functions", in the sense that they don't keep the instance
alive but rather consume it.
This is annotated with `(transfer full)`, but since these functions are
listed as methods, their first argument is not shown.
Instead, let's add a line to the docs of each consuming function that
clarifies this behavior.
Even if we disable font fallback, after adding Cantarell Regular
to the custom fontmap, fontconfig will helpfully synthesize
Cantarell Bold for us. So, just don't check for the font at all.
If there is a url, add it to the fontmap and leave it up to the
serializing code to ensure that we don't end up with duplicate
fonts.
The hb face is is a wrapper around the font file, which is what
we need to track here, since we want to subset and serialize each
used font file exactly once.
When serializing nodes, collect the glyphs that are used from
each font, subset the font to that set of glyphs, and embed it
into the node file. We are careful to preserve the glyph IDs,
so our text nodes transparently work with the subsettted fonts.
This way, we can simply duplicate the keys as separate pointers to store
the corresponding Vulkan handles so that we can safely hash them, as
Vulkan handles may or may not be pointers depending on the target
platform.
This will fix builds on 32-bit Windows at least.
This function does not use the standard __cdecl calling convention on
Windows, meaning using g_clear_pointer() on it directly will cause
crashes on 32-bit Windows. Just call it directly if the GLsync it uses
exists.
Switch symbolc icon drawing from color-matrix to mask nodes
make the performance of the iconscroll demo crater (from 60fps
to 10fps).
Apply the same optimization we already have for color-matrix
nodes when drawing mask nodes. This gets us back to 60fps.
Fixes: #6700
On Windows, gsize is a long long unsigned. The compiler complains about
that.
Use G_GSIZE_FORMAT which translates to %llu on Windows, %lu on most
platforms, and sometimes just %u on rare cases.
Due to rounding errors, it is possible after intersecting a lot of
rectangles to end up with a tiny size for an offscreen. And because we
allow an epsilon before ceil()ing to an integer (see commit afc7b46264
for details) it is now possible that we end up with a size of 0.
Avoid that by always enforcing a minimum size of 1px.
Test included
The test uses a different codepath to arrive at the same problem - it
specifies the small size instead of triggering it via rounding errors
and clipping like the original bug (and most likely the more common case
to encounter this problem.
Fixes#6656
Use a format of
[XXX] SYMBOL DETAILS
where SYMBOL indicates the offloading status:
🗙 - no offload
▲ - offload above, with background
△ - offload above, no background
▼ - offload below, with background
▽ - offload below, no background
The VK_IMAGE_LAYOUT_UNDEFINED layout means that the data hold by the
texture can be discarded, and we don't want to discard it. Because the
Vulkan spec is unclear (see [1] for a discussion), err on the side of
caution and use VK_IMAGE_LAYOUT_GENERAL.
Fixes import failures with WebKit.
[1] https://github.com/ValveSoftware/gamescope/issues/356
Spew a bit less per-frame. Unfortunately, we still spew for
every frame, and fixing that would require more extensive
refactoring to centralize all logging in gskoffload.c
The intent of this change to get wider testing and verify that the
Vulkan drivers we get to use in the wild are good enough for our
needs. If significant problems show up, we will revert this change
for 4.16.
The new preference order is vulkan > ngl > gl > cairo.
The gl renderer is still there because we need it to support gles2.
If you need to override the default renderer choice, you can
still use the GSK_RENDERER environment variable.
Fixes: #6537
Rename things so they make more sense. The dest/source naming got
a bit unclear when we added background into the mix. Now we're going
for:
source_rect - the texture region to display
texture_rect - dimensions of the subsurface showing the texture
background_rect - dimensions of the background subsurface
bounds - union of texture_rect and background_rect
Also use this opportunity to add some api docs.
Detect a black color node below the texture node and pass that
information to the subsurface, to take advange of the single-pixel
buffer optimization.
To make this work, we need to stop using the bounds of the subsurface
node for sizing the offload, and instead use either the clip or
the texture node for that.
Make it possible for subsurfaces to have a black background on a
secondary subsurface below the actual subsurface. Using a single-pixel
buffer for that background increases the changes that the compositor
will use direct scanout for the actual subsurface.
This changes the private subsurface API. All callers have been
updated to pass an empty background rect.
The compiler (gcc 13.2) thinks that `t` could be used uninitialised.
That’s obviously not the case, because there’s always going to be at
least one loop iteration due to the initial values of `t1` and `t2`.
Change the loop to a `do…while` to make that a bit clearer to the
compiler without making any functional changes to the code.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
The goal is to generate an offscreen at 1x scale.
When not ceil()ing the numbers the offscreen code would do it *and*
adjust the scale accordingly, so we'd end up with something like a
1.01x scale.
And that would cause the code to reenter this codepath with the goal to
generate an offscreen at 1x scale.
And indeed, this would lead to infinite recursion.
Tests included.
Fixes#6553
When we look for the texture to attach to the subsurface, keep
track of transforms we see along the way, and look at their scale
component to determine if the texture needs to be flipped.
We currently don't allow rotations here.
This fixes glarea rendering being upside-down when offloaded.
Allow to specify a D₂ transform when attaching a texture to a
subsurface, to handle flipped and rotated content. The Wayland
implementation handles these transforms by setting a buffer
transform on the subsurface.
All callers have been updated to pass GDK_TEXTURE_TRANSFORM_NORMAL.
This works better for cff fonts, where hinting is not as local as
what the autohinter does for ttf fonts, and it does not seem to
have negative effects.
Fixes: #6577Fixes: #6568
It turns out that we mispositioned glyphs with some cff fonts
when metrics hinting is off, and hinting is on. Since we don't
fully understand the interactions of these settings at this point,
lets preserve metrics hinting as it was on the font we got.
This at least gives folks a workaround for when they experience
clipped rendering with cff fonts: Turn on hint-metrics.
We forced hint metrics off here because it made Pango do some
creative wfh for hex boxes at small sizes, but I've dropped that
on the Pango side.
In a very particular situation, it could happen that our renderpass
reordering did not work out.
Consider this nesting of renderpasses (indentation indicates subpasses):
pass A
subpass of A
pass B
subpass of B
Out reordering code would reorder this as:
subpass of B
subpass of A
pass A
pass B
Which doesn't sound too bad, the subpasses happen before the passes
after all.
However, a subpass might be a pass that converts the image for a texture
stored in the texture cache and then updates the cached image.
If "subpass of A" is such a pass *and* if "subpass of B" then renders
with exactly this texture, then "subpass of B" will use the result of
"subpass of A" as a source.
The fix is to ensure that subpasses stay ordered, too.
The new order moves subpasses right before their parent pass, so the
order of the example now looks like:
subpass of A
pass A
subpass of B
pass B
The place where this would happen most common was when drawing thumbnail
images in Nautilus, the GTK filechooser or Fractal.
Those images are usually PNG files, which are straight alpha. They are then
drawn with a drop shadow, which requires an offscreen for drawing as
well as those images as premultipled sources, so lots of subpasses happen.
If there is then a redraw with a somewhat tricky subregion, then the
slicing of the region code could end up generating 2 passes that each draw
half of the thumbnail image - the first pass drawing the top half and the
second pass drawing the bottom half.
And due to the bug the bottom half would then be drawn from the
offscreen before the actual contents of the offscreen would be drawn,
leading to a corrupt bottom part of the image.
Test included.
Fixes: #6318
We write the buffers in small chunks, and we even sometimes read it. So
prefer it when it's cached.
Speeds up the text benchmarks by a factor of 3x on my dedicated GPU.
If glBufferStorage() is available, we can replace our usage of
glBufferSubData() with persistently mapped storage via
glMappedBufferRange().
This has 1 disadvantage:
1. It's not supported everywhere, it requires GL 4.4 or
GL_EXT_buffer_storage. But every GPU of the last 10 years should
implement it. So we check for it and keep the old code.
The old code can also be forced via GDK_GL_DISABLE=buffer-storage.
But it has 2 advantages:
1. It is what Vulkan does, so it unifies the two renderers' buffer
handling.
2. It is a significant performance boost in use cases with large vertex
buffers. Those are pretty rare, but do happen with lots of text at a
small font size. An example would be a small font in a maximized VTE
terminal or the overview in gnome-text-editor.
A custom benchmark tailored for this problem can be created with:
tests/rendernode-create-tests 1000000 text.node
This creates a node file called "text.node" that draws 1 million text
nodes.
(Creating that test takes a minute or so. A smaller number may be useful
on less powerful hardware than my Intel Tigerlake laptop.)
The difference can then be compared via:
tools/gtk4-rendernode-tool benchmark --runs=20 text.node
and
GDK_GL_DISABLE=buffer-storage tools/gtk4-rendernode-tool benchmark --runs=20 text.node
For my laptop, the difference is:
before: 1.1s
after: 0.8s
Related: !7021
It's not just unused, it's also wrong.
We are reading from the buffer when reallocating the vertex buffer
and memcpy()ing the old into the new buffer - at that point we read from
it.
When ops get allocated that use the same stats as the last op, put them
into the same ShaderOp. This reduces the number of ShaderOps we need to
record, which has 3 benefits:
1. It's less work when iterating over all the ops.
This isn't a big win, but it makes submit() and print() run a bit
faster.
2. We don't need to manage data per-op.
This is a large win because we don't need to ref/unref descriptors
as much anymore, and refcounting is visible on profiles.
3. We save memory.
This is a pretty big win because we iterate over ops a lot, and when
the array is large enough (I've managed to write testcases that makes
it grow to over 4GB) it kills all the caches and that's bad.
The main benefit of all this are glyphs, which used to emit 1 ShaderOp
per glyph and can now end up with 1 ShaderOp for multiple text nodes,
even if those text nodes use different fonts or colors - because they
can all share the same ColorizeOp.
With potentially multiple ops per ShaderOp, we may encounter situations
where 1 ShaderOp contains more ops than we want to merge. (With
GSK_GPU_SKIP=merge, we don't want to merge at all.)
So we still merge the ShaderOps (now unconditionally), but we then run
a loop that potentially splits the merged ops again - exactly at the
point we want to.
This way we can merge ops inside of ShaderOps and merge ShaderOps, but
still have the draw calls contain the exact number of ops we want.
This just introduces the variable and sets it to 1 everywhere.
The ultimate goal is to allow one ShaderOp to collect multiple ops into
one, thereby saving memory in the ops array and leading to faster
performance.
Instead of having renderer API to wait for any number of frames, just
have gsk_gpu_frame_wait() to wait for a single frame.
This unifies behavior on Vulkan and GL, because unlike Vulkan, GL does
not allow waiting for multiple fences.
To make up for it, we replace waiting for multiple frames with finding
the frame with the earliest timestamp and waiting for that one.
Also implement wait() for GL.
This copies the Vulkan idea of using a fence at the end of command
submission and waiting until it gets signaled before reusing the frame.
This frees up the GL driver from doing the work of making buffers etc
reusable and instead allocates new ones when they're still in use and is
a pretty massive performance win.
Most of the time, the image we get for the glyphs will be the
same (the atlas), so avoid adding it to the descriptor set over
and over, and check first if have to. This matches what the
pattern variant of this function already does.
Just initialize the rect directly. This matches better what the
pattern variant of this method does, and it also has the nice
side-effect of eliminating the handling of negative scales in
gsk_rect_scale, which we don't need here, since our scales are
always positive.
Make a single gsk_reload_font helper that can tweak both
scale and font options, so we can ensure that our scaled
font has hint-metrics turned off (pango pays attention to
hint metrics when sizing and rendering hex boxes, and that
hurts us.
This is a tricky topic, because it can make the clip bounds grow, so
previously we were trying to be careful.
However, this can cause perfectly trivial intersections to fail that are
caused by redraw diff regions.
And in the worst case, that means we offscreen in places where we
absolutely do not want to offscreen - in subtrees with subsurface nodes.
Fixes#6499
CLIP_TYPE_NONE is valid if the clip is implemented by the scissor rect.
We always have a scissor rect and there's no way to draw outside of it.
In theory that means we can reset the clip to NONE at any point we
wish if we know nodes are contained inside a certain pixel-aligned
rectangle we can clip.
In practice that's probably quite hard...
We were turning off hinting and subpixel positioning if the
transform isn't 2D affine. The idea behind this was that transforms
likely indicate animations, and for animations, this may reduce
jitter. But the heuristic of transform==animation is not very
reliable, and we pay for this with a jump from hinted to unhinted
at the beginning and end of it. Also, the heuristic does not even
work for the most relevant 'animation' we have today: scrolling.
So, lets drop this for now. We can revisit it later.
When getting the hinted version of fonts, they often come in sequentially.
This helps reduce overhead in many sequential gtk_text_node_new() on with
fractional scaling as you see from GtkSourceView.
Some maps are used for read only and do not require uploading contents
back to the GPU afterwards. In other cases, we can often upload less than
the fully allocated buffer size.
When transforming an empty clip, it stays empty.
Previously, we were setting it to CONTAINED, but that's wrong, because
the bounds are not contained in the clip, the clip is contained in the bounds.
This reverts part of commit a51c6aed47.
Related: !6692
When scaling a font or changing font options, we need to be
careful to preserve the dpi as well, otherwise the rendering
might leak out of the node bounds, leading to spectacular
glitches.
Fixes: #6508
Enforce the following rules:
- No hinting or subpixel positioning in transformed context
- glyph-align determines if we use integral or fractional
device pixel positions
- For hinting, always use an integral y position (the hinter
assumes integral positions, and only operates vertically).
When we get an unhinted font for text node extents, don't change
the antialiasing setting. It doesn't affect the extents we get
here, but if we later need an unhinted font for rendering, the
one we create this way will be the right one, so it will already
exist.
The goal is to fix all the context that influences the rendering
of text nodes in the node file. This will help with better font
testing.
The newly accepted properties are
hint-style: none/slight/full
antialias: none/gray
We are omitting font options and values that aren't supported
in GSK or have no influence on the rendering.
Note that these settings will get incorporated in the PangoFont
that gets set on the resulting text node.
Parser tests included.
We need precise bounds. And while hinting might shift the rendering
around from these bounds by a fraction of a pixel, we account for
this in the places where it matters: when determining diff regions,
when sizing offscreens, and when determining the size of atlas
regions for glyphs.
Add a function to change the cairo font options of a font to
to the given values while keeping everything else the same.
We use pango api for this if available.
Note that this is not a fully general api, but tailored to the
needs of GSK. We don't allow setting hint-metrics (because it
only influences layout, not rendering) or subpixel-mode (since
we don't have component alpha available).
This changes the approach we take to rendering glyphs in the
presence of a scale transform: Instead of scaling the extents
and rendering to an image surface with device scale, simply
create a scaled font and use it for extents and rendering.
This avoids clipping problems with scaling of extents in
the presence of hinting.
The pango code that is drawing hex boxes, invisible glyphs, etc,
is depending on the width being set in the PangoGlyphInfo. Once
we set that, everything falls into place.
Testcase included.
It is a bit annoying that one has to specify the glyph width
when specifying glyphs numerically for a text node, since this
information really is part of the font.
Make the parser more flexible, and allow to specify just the glyph
ids, without an explicit width. In this case, the width will be
determined from the font.
With this, glyphs can now be specified in any of the follwing
ways:
glyphs: "ABC"; (ASCII)
glyphs: 23, 45, 1001; (Glyph IDs)
glyphs: 23 10, 100 11.1; (Glyph IDs and advance widths)
glyphs: 23 10 1 2 color; (with offsets and flags)
Tests have been updated to cover these variants.
We were just assuming they were if the format matches.
Fixes crashes in Webkit where the external texture is actually a dmabuf
imported as an EGL image.
Avoids getting the scale wrong when due to a rounding error our
pixel-aligned rectangle is 5.000000003px big and we ceil() to 6px
and produce blurry output.
Fixes#6439
The code was written under the assumption that the corners of
the rounded rect are disjoint. If they aren't, there are a few
more cases to consider.
Fixes: #6440
We lost this when a bunch of rect code was inlined in
commit 36314f28e2, and as it turns out, that broke some
applications. So, bring it back.
Fixes: #6435
Fixes blurriness in shadows.
Not sure to do a proper test for this feature. Usually proper pixel
alignment is tested by drawing a crips line and checking that it is
indeed crisp. But we are testing the blur operation here...
Fixes#6380
This isn't really a useful thing in itself, because none of the callers
handle the NULL return.
But the resulting crash is easier to debug when it's a NULL image than
when add_node() is called on an uninitializes NodeProcessor.
In GSK the following pattern is used four times:
```
switch (self->filter)
{
default:
g_assert_not_reached ();
G_GNUC_FALLTHROUGH;
case GSK_GPU_BLIT_LINEAR:
filter = GL_LINEAR;
break;
case GSK_GPU_BLIT_NEAREST:
filter = GL_NEAREST;
break;
}
```
The G_GNUC_FALLTHROUGH macro is not required. When G_DISABLE_ASSERT
is defined the body of the `default` case is empty, thus there is
no need. When G_DISABLE_ASSERT is not defined the body of the `default`
case contains g_assert_not_reached() thus it won't fallthrough.
This resolves the following:
```
[221/1379] Compiling C object gsk/libgsk.a.p/gpu_gskgpublitop.c.o
[...]
error: fallthrough annotation in unreachable code [-Werror,-Wimplicit-fallthrough]
1 error generated.
```
This can be helpful to see that there is an enormous scale blowing
things up. We omit the matrix, since it is 16 floats that are hard
to interpret at a glance.
Unless the renderer has been explicitly selected via the
GSK_RENDERER environment variable, don't use it with llvmpipe.
It is important that we allow explicit setting to override
this, so we can continue to use ngl in ci, where we don't
have hw and want to test with llvmpipe.
This should address many of the "performance is terrible in
GNOME OS" complaints that are coming from people running in
VMs, etc.
