1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-18 05:55:07 +00:00
serenity/Userland/Libraries/LibWeb/Painting/ViewportPaintable.h
Aliaksandr Kalenik ac6b3c989d 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.
2023-12-30 11:10:24 +01:00

31 lines
701 B
C++

/*
* Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <LibWeb/Painting/PaintableBox.h>
namespace Web::Painting {
class ViewportPaintable final : public PaintableWithLines {
JS_CELL(ViewportPaintable, PaintableWithLines);
public:
static JS::NonnullGCPtr<ViewportPaintable> create(Layout::Viewport const&);
virtual ~ViewportPaintable() override;
void paint_all_phases(PaintContext&);
void build_stacking_context_tree_if_needed();
void collect_scroll_frames(PaintContext&) const;
private:
void build_stacking_context_tree();
explicit ViewportPaintable(Layout::Viewport const&);
};
}