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
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.
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
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).
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.
