mirror of
https://github.com/RGBCube/serenity
synced 2025-07-26 04:37:44 +00:00
LibWeb: Apply scroll boxes offsets after painting commands recording
With this change, instead of applying scroll offsets during the recording of the painting command list, we do the following: 1. Collect all boxes with scrollable overflow into a PaintContext, each with an id and the total amount of scrolling offset accumulated from ancestor scrollable boxes. 2. During the recording phase assign a corresponding scroll_frame_id to each command that paints content within a scrollable box. 3. Before executing the recorded commands, translate each command that has a scroll_frame_id by the accumulated scroll offset. This approach has following advantages: - Implementing nested scrollables becomes much simpler, as the recording phase only requires the correct assignment of the nearest scrollable's scroll_frame_id, while the accumulated offset from ancestors is applied subsequently. - The recording of painting commands is not tied to a specific offset within scrollable boxes, which means in the future, it will be possible to update the scrolling offset and repaint without the need to re-record painting commands.
This commit is contained in:
parent
d3025668a4
commit
ac6b3c989d
12 changed files with 307 additions and 24 deletions
|
@ -57,4 +57,22 @@ void ViewportPaintable::paint_all_phases(PaintContext& context)
|
|||
stacking_context()->paint(context);
|
||||
}
|
||||
|
||||
void ViewportPaintable::collect_scroll_frames(PaintContext& context) const
|
||||
{
|
||||
i32 next_id = 0;
|
||||
for_each_in_subtree_of_type<PaintableBox>([&](auto const& paintable_box) {
|
||||
if (paintable_box.has_scrollable_overflow()) {
|
||||
auto offset = paintable_box.scroll_offset();
|
||||
auto ancestor = paintable_box.parent();
|
||||
while (ancestor) {
|
||||
if (ancestor->is_paintable_box() && static_cast<PaintableBox const*>(ancestor)->has_scrollable_overflow())
|
||||
offset.translate_by(static_cast<PaintableBox const*>(ancestor)->scroll_offset());
|
||||
ancestor = ancestor->parent();
|
||||
}
|
||||
context.scroll_frames().set(&paintable_box, { .id = next_id++, .offset = -offset });
|
||||
}
|
||||
return TraversalDecision::Continue;
|
||||
});
|
||||
}
|
||||
|
||||
}
|
||||
|
|
Loading…
Add table
Add a link
Reference in a new issue