Stop converting between CSS and device pixels as part of rendering - the
display list should be as simple as possible, so convert to DevicePixels
once when constructing the display list.
Per the CSS Overflow spec, overflow properties apply only to block
containers, flex containers, and grid containers — not SVG graphics
elements. Add an `is<SVGPaintable>` check in
`overflow_property_applies()` to return false for SVG inner elements
like `<g>`, `<rect>`, `<path>`.
This doesn't affect `<svg>` elements (which use `SVGSVGPaintable`, a
direct `PaintableBox` subclass) or `<foreignObject>` (which uses
`SVGForeignObjectPaintable`, a `PaintableWithLines` subclass) — both
correctly keep their overflow clips.
These rects are computed from immutable layout data but were
recomputed from scratch on every call, with the CSSPixels saturating
arithmetic showing up as a significant cost in profiles.
Cache them lazily alongside the existing m_absolute_rect cache.
This was 3.3% of CPU time while playing a YouTube video.
This means we don't need to include `FilterValueListStyleValue.h` in as
many places - reducing the rebuild from editing that file from 717 files
to 19.
When the mouse is dragged from inside a scrollable container to outside
of it, we now automatically scroll the container so the selection can be
extended. Scroll speed scales with the distance past the scrollport
edge, capped at a maximum. Edges close to the viewport boundary get a
wider activation zone so the speed ramp works predictably even when the
mouse has limited room to move.
The logic is encapsulated in AutoScrollHandler, which EventHandler
creates lazily on mouse selection start.
If the scrollbar was made to be invisible, it should no longer have a
size. This actually disables the scrollbar functionality - previously it
was only invisible, but still worked - and allows hit testing to pass
through to elements and fragments behind it.
When a sticky element was inside a position:fixed ancestor,
nearest_scroll_frame() would stop at the fixed boundary and return
nullptr. This caused precompute_sticky_constraints() to bail out,
leaving the sticky element at its normal flow position with no offset.
Replace direct ScrollFrame access via own_scroll_frame_offset() with
ScrollStateSnapshot-based lookup. This aligns compute_scrollbar_data()
with the rest of the painting/hit-testing pipeline, which uses snapshots
for consistent, thread-safe scroll state.
Compute the perspective matrix on the fly during visual context
assignment instead of caching it in PaintableBox. This reduces
PaintableBox's size and keeps the logic closer to where it's used.
Instead of computing and caching the transform matrix and transform
origin on PaintableBox during resolve_paint_properties(), compute them
inline during assign_accumulated_visual_contexts() where they are
actually consumed. This makes PaintableBox smaller by not wasting space
for properties that are only consumed during AccumulatedVisualContext
tree construction.
Precompute the geometric data needed for sticky positioning during
scroll frame assignment. This avoids walking the paintable tree to query
containing blocks and ancestor geometry during scroll state refresh,
which runs on every scroll event.
In PaintableBox::set_scroll_offset(), the code unconditionally
dereferenced dom_node() which returns null for pseudo-elements,
causing a crash when processing scroll events.
Now we check for pseudo-elements and use the generating element
as the scroll event target.
Previously, hit testing would return early for elements with
visibility: hidden, which prevented their visible children from being
hit. Now we traverse children even for hidden elements, allowing visible
descendants to be hit while still preventing the hidden elements
themselves from being hit.
The key changes:
- PaintableBox::hit_test() and PaintableWithLines::hit_test() no longer
return early for hidden elements, but still skip chrome hit testing
and the final hit result for them
- hit_test_fragments() now checks is_visible() on each fragment's
paintable to skip hidden text
This matches the CSS specification where visibility is inherited but
children can override it with visibility: visible.
Previously, both mask and clip-path were rendered to separate mutable
Gfx::Bitmap objects which forced CPU rasterization. They were then
combined using a CPU pixel-by-pixel operation before being returned
as an ImmutableBitmap.
Instead of including mask in the final bitmap as already rasterized
images, we now use display lists which opens opportunity to utilize
GPU if available.
Bitmap::apply_mask() and ApplyMaskBitmap display list command are no
longer used and have been removed.
This change adds border-radius awareness to hit testing in two places:
1. ClipData::contains() now uses BorderRadiiData::contains() to properly
check if a point is inside a rounded clip rect. This handles overflow
clips from ancestor elements that have border-radius.
2. PaintableBox::hit_test() now directly checks the element's own
border-radius before reporting a hit.
Effects (opacity, blend mode, filters) must be applied in the parent's
coordinate space, before the element's transform. Previously this was
handled by manually switching to the parent's visual context when
applying effects at paint time.
By adding EffectsData to AccumulatedVisualContext and positioning it
before TransformData in the chain, effects are now naturally applied in
the correct order during display list replay, eliminating the special
case in StackingContext::paint().
For SVG filters that can generate content from empty elements (feFlood,
feImage, feTurbulence), a transparent FillRect command is emitted to
trigger the filter through the same AVC pipeline.
This moves filter resolution from display list recording time to
resolve_paint_properties(), caching the resolved values in CSS pixels
on PaintableBox. Device pixel conversion is now deferred until paint
time via to_gfx_filter().
This follows the existing pattern used for other paint-only properties
like box shadows and border radii.
When paintable trees are preserved across relayouts, the paint
properties are re-resolved. If an element previously had a perspective
property but no longer does, the m_perspective_matrix needs to be
explicitly cleared, otherwise the stale value persists and produces
incorrect rendering.
Reuse existing paintables during relayout to reduce GC allocation
pressure. Each paintable subclass implements reset_for_relayout()
to clear state before reuse.
This method was initially introduced to calculate the total paint area
including effects like box-shadows that paint outside the border box.
It was used in StackingContext for sizing bitmaps when painting
elements with opacity or transforms, and later for clip-path bounds.
This functionality is no longer needed as stacking context painting
and clip-path handling have been refactored to use different
approaches (AccumulatedVisualContext now handles clip-path).
Remove the now-obsolete ClipFrame infrastructure:
- Delete ClipFrame.h and ClipFrame.cpp
- Remove assign_clip_frames() from ViewportPaintable
- Remove enclosing_clip_frame and own_clip_frame from PaintableBox
- Remove m_clip_state HashMap from ViewportPaintable
Clip handling is now fully managed through AccumulatedVisualContext
nodes with ClipData.
Integrate AccumulatedVisualContext with display list recording and
playback. This is the main commit of the refactoring that delivers the
architectural improvements enabled by AccumulatedVisualContext.
Recording changes:
Each display list command now stores a single
RefPtr<AccumulatedVisualContext> instead of separate scroll_frame_id
and ClipFrame. The recorder simply captures the current accumulated
context when appending commands.
The before_paint()/after_paint() hooks that pushed/popped scroll frame
IDs are replaced by directly setting accumulated_visual_context on the
recorder before painting each element.
Playback changes:
The display list player now uses LCA (Lowest Common Ancestor) based
traversal to switch between visual contexts efficiently. When
transitioning from context A to context B:
1. Find the LCA of A and B in the context tree
2. Pop (restore) states back to the LCA depth
3. Push (save + apply) states from LCA down to B
This approach minimizes redundant save/restore operations. For example,
when rendering siblings that share a common scroll container, the
player keeps that scroll state applied and only switches the divergent
parts of their context chains.
Key deletions:
- Remove translate_by() from all 45 display list commands - commands
are now immutable
- Remove transform/perspective fields from PushStackingContext -
transforms are tracked via AccumulatedVisualContext
- Remove push_scroll_frame_id()/pop_scroll_frame_id() from
DisplayListRecorder
- Remove before_paint()/after_paint() hooks from Paintable
- Merge ApplyOpacity, ApplyCompositeAndBlendingOperator, ApplyFilter
into single ApplyEffects command
Stacking context painting changes:
The StackingContext::paint() method is significantly simplified.
Instead of building a PushStackingContextParams struct with transform
matrices and pushing/popping stacking contexts, it now:
1. Sets the accumulated visual context (which already contains
transforms)
2. Applies effects (opacity, blend mode, filters) if needed
3. Applies clip path if needed
4. Paints the content
5. Restores state
The visual state management that was interleaved throughout the
painting code is now handled uniformly by the context tree.
Add ElementResizeAction to Page (maybe there's a better place). It's
just a mousemove delegate that updates styles on the target element.
Add ChromeMetrics for zoom-invariant chrome like scrollbar thumb
thickness, resize gripper size, paddings, etc. It's not user-stylable
but separates basic concerns in a way that a visually gifted
designer unlike myself can adjust to taste.
These values are pre-divided by zoom factor so that PaintableBox can
continue using device_pixels_per_css_pixel calls as normal.
The adjusted metrics are computed on demand from Page multiple times
per paint cycle, which is not ideal but avoids lifetime management and
atomics. Maybe someone with more surety about the painting flow control
can improve this, but it won't be a huge win. If profiling shows
this slowing paints, then Ladybird is in good shape.
Update PaintableBox to draw the resize gripper and deconflict
the scrollbars. Set apropriate cursors for scrollbars and gripper in
mousemove. We override EventHandler's cursor handling because nothing
should ever come between a man and his resize gripper.
Chrome metrics use the CSSPixels class. This is good because it's
broadly compatible but bad because they're actually different units
when zoom is not 1.0. If that's a problem, we could make a new type
or just use double.
A lot of our scrolling code is quite old, and doesn't match the spec,
but does use some similar names. This is quite confusing. In particular
`perform_scroll_of_viewport()` is not the same as the spec algorithm.
That algorithm is actually almost implemented in
`scroll_viewport_by_delta()`.
To clarify things, this commit makes a few changes:
- Rename perform_scroll_of_viewport() to
perform_scroll_of_viewport_scrolling_box(). This is a better match
for how we use this method, even if it's not actually a match for the
algorithm. (:yakbait:)
- Move `scroll_viewport_by_delta()`'s code into a new
`perform_a_scroll_of_the_viewport()` method, and make it take a
position like it should. `scroll_viewport_by_delta()` now calls it
with a calculated position.
I've avoided reusing the original `perform_scroll_of_viewport()` name to
avoid accidents.
This adds visit_edges(Cell::Visitor&) methods to various helper structs
that contain GC pointers, and makes sure they are called from owning
GC-heap-allocated objects as needed.
These were found by our Clang plugin after expanding its capabilities.
The added rules will be enforced by CI going forward.
The Transformation class wasn't really accomplishing anything. It still
had to store StyleValues, so it was basically the same as
TransformationStyleValue, with extra steps to convert from one to the
other. So... let's just use TransformationStyleValue instead!
Apart from moving code around, the behavior has changed a bit. We now
actually acknowledge unresolvable parameters and return an error when
we try to produce a matrix from them. Previously we just skipped over
them, which was pretty wrong. This gets us an extra pass in the
typed-om test.
We also get some slightly different results with our transform
serialization, because we're not converting to CSSPixels and back.
Instead of calculating the cursor rect separately, reuse
PaintableFragment::range_rect() and check for the selection state of
'None' where appropriate.
