Paintable::display() was chasing through layout_node().display() which
goes through computed_values().display() on every call. Since display
never changes after the Paintable is constructed, cache it as a member
set in the constructor.
This was 1.6% of CPU time while playing a YouTube video.
Cache the result of the visibility+opacity check as a bit field
(m_visible) computed in resolve_paint_properties(), which already runs
before each paint when paint properties need updating.
This makes Paintable::is_visible() a simple inline bit field read
instead of chasing through layout_node->computed_values() every time.
This was 3.3% of CPU time while playing a YouTube video.
Previously, text selection always used the system highlight color. This
implements support for the ::selection pseudo-element's background-color
and color properties.
For form controls like <input> and <textarea>, the selection style is
looked up on the shadow host element, since the actual text lives inside
their shadow DOM.
The text painting logic has been refactored to split fragments into
styled spans (before selection, selected, after selection) so that each
portion can be rendered with its appropriate colors, taking care not to
allocate in 99%+ of fragment rendering cases.
Reuse existing paintables during relayout to reduce GC allocation
pressure. Each paintable subclass implements reset_for_relayout()
to clear state before reuse.
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.
...instead of reaching into DOM tree during hit-testing in order to
figure out if an element is inert. This is a part of the effert to make
possible running hit-testing solely based on data contained by the
paintable tree.
Before this change, we always updated paint-only properties for every
single paintable after layout or style changes.
This could get very expensive in large documents, so this patch makes
it something we can do partially based on "repaint" invalidations.
This cuts down time spent in paint-only property update when scrolling
https://imdb.com/ from 19% to 5%.
The overlay shown for the node hovered in the inspector is painted as
part of the normal tree traversal of all paintables. This works well in
most cases, but falls short in specific scenarios:
* If the hovered node or one of its ancestors establishes a stacking
context and there is another element that establishes a stacking
context close by or overlapping it, the overlay and especially the
tooltip can become partially hidden behind the second element. Ditto
for elements that act as if they established a stacking context.
* If the hovered node or one of its ancestors involves clipping, the
clip is applied to the overlay and espicially the tooltip. This can
cause them to be partially invisible.
* Similarly, if the hovered node or one of its ancestors has a defined
mask, the mask is applied to the overlay, often making it mostly
invisible.
* No overlays are shown for SVG nodes because they are painted
differently from HTML documents.
Some of these problems may be fixable with the current system. But some
seem like they fundamentally cannot work fully when the overlays are
painted as part of the regular tree traversal.
Instead we pull out painting the overlay as a separate pass executed
after the tree traversal. This way we ensure that the overlays are
always painted last and therefore on top of everything else. This also
makes sure that the overlays are unaffected by clips and masks. And
since overlay painting is independent from painting the actual elements,
it just works as well.
However we need to be careful, because we still need to apply some of
the steps of the tree traversal to get the correct result. Namely we
need to apply scroll offsets and transforms. To do so, we collect all
ancestors of the hovered node and apply those as if we were in the
normal tree traversal.
This reverts commit 7dc8062283.
This did not propagate correctly to paintables whose style was inherited
from an ancestor, causing rendering artifacts on https://linear.app/
PaintContext dates back to a time when display lists didn't exist and it
truly represented "paint context". Renaming it to better align with its
current role.
Before committing a new layout (and thus building a new paint tree)
we now go through both the old paint tree and the layout tree and detach
them from each other.
This is a little extra work, but it ensures that there are no lingering
references across the trees, which we were apparently accumulating in
some cases on Discord, causing GC leaks.
The faux position we created here is adjusted by the device pixel ratio
later on, which would invoke integer overflow on screens with a DPR
greater than 1.
Instead of creating special data for a mouse move event, let's just add
an explicit leave event handler.
6507d23 introduced a bug when snapshot for iframe is saved in
`PaintNestedDisplayList` and, since display lists are immutable, it's
not possible to update before the next repaint.
This change fixes the issue by moving `ScrollStateSnapshot` for
nested display lists from `PaintNestedDisplayList` to
`HashMap<NonnullRefPtr<DisplayList>, ScrollStateSnapshot>` that is
placed into pending rendering task, making it possible to update
snapshots for all display lists before the next repaint.
This change doesn't have a test because it's really hard to make a ref
test that will specifically check scenario when scroll offset of an
iframe is advanced after display list is cached. We already have
`Tests/LibWeb/Ref/input/scroll-iframe.html` but unfortunately it did
not catch this bug.
Fixes https://github.com/LadybirdBrowser/ladybird/issues/5486
Previously, we always applied the enclosing clip rectangle for all paint
phases except overlays, and the own clip rectangle for the background
and foreground phases. The problem is that applying a clip rectangle
means emitting an AddClipRect display list item for each clip rectangle
in the containing block. With this change, we choose whether to include
the own clip based on the paint phase and this way avoid emitting
AddClipRect for enclosing clip rectangles twice.
These were only used in SVGSVGPaintable to apply scroll frame id, which
is already handled by `before_paint()` and `after_paint()` hooks in
PaintableBox.
For every invocation of `::before_paint()` and `::after_paint()`, we
would reach into the node's computed values to determine its visibility.
Let's just do this once during construction of the paintable instead,
since this was showing up in profiles.
This patch adds a workaround for a Swift issue where boolean bitfields
with getters and setters in SWIFT_UNSAFE_REFERENCE types are improperly
imported, causing an ICE.
The `cursor` property accepts a list of possible cursors, which behave
as a fallback: We use whichever cursor is the first available one. This
is a little complicated because initially, any remote images have not
loaded, so we need to use the fallback standard cursor, and then switch
to another when it loads.
So, ComputedValues stores a Vector of cursors, and then in EventHandler
we scan down that list until we find a cursor that's ready for use.
The spec defines cursors as being `<url>`, but allows for `<image>`
instead. That includes functions like `linear-gradient()`.
This commit implements image cursors in the Qt UI, but not AppKit.
This reduces the number of `.cpp` files that need to be recompiled when
one of the below header files changes as follows:
CSS/ComputedProperties.h: 1113 -> 49
CSS/ComputedValues.h: 1120 -> 209
This reduces the number of `.cpp` files that need to be recompiled when
one of the below header files changes as follows:
Painting/Command.h: 1030 -> 61
Painting/DisplayList.h: 1030 -> 60
Painting/DisplayListRecorder.h: 557 -> 59
For example, in the following HTML:
```html
<label>
<input type="radio" name="fruit" value="apple" id="radio1">
<span class="box"></span>
</label>
```
When any descendant of a <label> element is clicked, a "click" event
must be dispatched on the <input> element nested within the <label>, in
addition to the "click" event dispatched on the clicked descendant.
Previously, this behavior was implemented only for text node descendants
by "overriding" the mouse event target using `mouse_event_target()` in
the TextPaintable. This approach was incorrect because it was limited to
text nodes, whereas the behavior should apply to any box. Moreover, the
"click" event for the input control must be dispatched *in addition* to
the event on the clicked element, rather than redirecting it.
For a while we used the wider Paintable type for stacking context,
because it was allowed to be created by InlinePaintable and
PaintableBox. Now, when InlinePaintable type is gone, we can use more
specific PaintableBox type for a stacking context.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
