Instead of carrying the display list for a mask in each command that
might potentially be affected by "background-clip: text", this change
introduces a new AddMask command that is applied once for all
background layers within one box.
The new AddMask command includes a rectangle for the mask destination
that is translated by the corresponding scroll offset.
Fixes https://github.com/LadybirdBrowser/ladybird/issues/857
Contrary to LibGfx, where corner clipping was implemented by sampling
and blitting pixels under corners into a temporary bitmap, Skia allows
us to simply apply a mask. As a result, we no longer need the
BlitCornerClipping command, which has become a no-op.
- SampleUnderCorners is renamed to AddRoundedRectClip
- The optimization that skipped unnecessary blit and sample commands has
been removed. However, this should not result in a performance
regression because Skia seems to perform mask rasterization lazily.
Before this change, "background-clip: text" was implemented by saving a
Vector<Gfx::Path> of all glyphs needed to paint a mask for the
background. The issue with this approach was that once glyphs were
extracted into vector paths, the glyph rasterization cache could no
longer be utilized.
With this change, all text required for mask painting is saved in a
nested display list and rasterized as a regular text.
With this change, instead of recording a display list item for each
instance of a repeated background, a new DrawRepeatedImmutableBitmap
type is used. This allows the painter to use optimized repeated image
painting and, when the GPU backend is used, avoid re-uploading the image
texture for each repetition.
Some screenshot tests are affected, but there are no visible
regressions.
https://null.com/games/chainstaff works a lof faster with this change.
Implements the same optimization we already have for DrawGlyphRun by
saving unscaled glyph run and scale factor in a painting command, which
allows to avoid copying of glyphs vector to apply scaling during
recording.
This change is a preparation before introducing Skia painter in an
upcoming change. It's needed because Skia does not have an API to
implement ClearClipRect command. It only allows to return previous
clip rect by popping from its internal state stack.
A bit more context: initially we had save and restore commands, but
their frequent use led to many reallocations of vector during painting
commands recording. To resolve this, we switched to SegmentedVector to
store commands list, which allows fast appends. Now, having many save
and restore commands no longer causes noticeable performance issue.
Before this change we were painting inner shadows lying outside of
viewport.
Improves painting performance on Github and Twitter where this command
is used a lot.
`Painting::paint_all_borders()` only uses `.draw_line()` for simple
borders and `.fill_path()` for more complex cases. These are both
already supported by the `RecordingPainter` so removing this command
simplifies the painting API.
Two test changes:
css-background-clip-text: Borders are now drawn via the AA painter
(which makes them closer to how they appear in other browsers).
corner-clip-inside-scrollable: Borders removed (does not change test)
due to imperceptible sub-pixel changes.
PaintFrame is not primitive painting command, we inherited from OS, that
is hard to replicate in GPU-painter or alternative CPU-painter API. We
should remove it as a part of refactoring towards simplifying recording
painter commands set.
Fixes: #23796
From https://drafts.csswg.org/css-backgrounds-4/#background-clip
"The background is painted within (clipped to) the intersection of the
border box and the geometry of the text in the element and its in-flow
and floated descendants"
This change implements it in the following way:
1. Traverse the descendants of the element, collecting the Gfx::Path of
glyphs into a vector.
2. The vector of collected paths is saved in the background painting
command.
3. The painting commands executor uses the list of glyphs to paint a
mask for background clipping.
Co-authored-by: Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
...to avoid allocating a copy of glyph run for painting commands. We
can't simply save pointers to a glyph run in layout/paintable tree
because it should be safe to deallocate layout and paintable trees
after painting commands are recorded, if in the future we decide to
move command execution to a separate thread.
Instead of allocating a new glyph run to scale glyph positions and
fonts, a scale factor could be encoded in a paint command and applied
later during command execution.
Instead of allocating a new glyph run solely to shift each glyph by the
painter's offset, this offset could be encoded in a paint command and
applied later during command execution.
Separating the recorder list from the painter will allow us to save it
for later execution without carrying along the painter's state. This
will be useful once we have a separate thread for executing painting
commands, to which we will have to transfer commands from the main
thread.
Preparation for https://github.com/SerenityOS/serenity/pull/23108
