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LibWeb: Use DOM Selection instead of ad-hoc layout tree selection

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Before this patch, we were expressing the current selection as a range
between two points in the layout tree. This was a made-up concept I
called LayoutRange (2x LayoutPosition) and as it turns out, we don't
actually need it!

Instead, we can just use the Selection API from the Selection API spec.
This API expresses selection in terms of the DOM, and we already had
many of the building blocks implemented.

To ensure that selections get visually updated when the underlying Range
of an active Selection is programmatically manipulated, Range now has
an "associated Selection". If a range is updated while associated with
a selection, we recompute layout tree selection states and repaint the
page to make it user-visible.
This commit is contained in:
Andreas Kling 2023-01-11 19:48:53 +01:00
parent 1c4328902d
commit b79bc25a1f
9 changed files with 161 additions and 71 deletions
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76
Userland/Libraries/LibWeb/Layout/InitialContainingBlock.cpp
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@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/DOM/Range.h>
#include <LibWeb/Dump.h>
#include <LibWeb/Layout/InitialContainingBlock.h>
#include <LibWeb/Painting/PaintableBox.h>
@ -18,6 +19,11 @@ InitialContainingBlock::InitialContainingBlock(DOM::Document& document, NonnullR
InitialContainingBlock::~InitialContainingBlock() = default;
JS::GCPtr<Selection::Selection> InitialContainingBlock::selection() const
{
return const_cast<DOM::Document&>(document()).get_selection();
}
void InitialContainingBlock::build_stacking_context_tree_if_needed()
{
if (paint_box()->stacking_context())
@ -56,40 +62,52 @@ void InitialContainingBlock::paint_all_phases(PaintContext& context)
void InitialContainingBlock::recompute_selection_states()
{
SelectionState state = SelectionState::None;
auto selection = this->selection().normalized();
// 1. Start by resetting the selection state of all layout nodes to None.
for_each_in_inclusive_subtree([&](auto& layout_node) {
if (!selection.is_valid()) {
// Everything gets SelectionState::None.
} else if (&layout_node == selection.start().layout_node && &layout_node == selection.end().layout_node) {
state = SelectionState::StartAndEnd;
} else if (&layout_node == selection.start().layout_node) {
state = SelectionState::Start;
} else if (&layout_node == selection.end().layout_node) {
state = SelectionState::End;
} else {
if (state == SelectionState::Start)
state = SelectionState::Full;
else if (state == SelectionState::End || state == SelectionState::StartAndEnd)
state = SelectionState::None;
}
layout_node.set_selection_state(state);
layout_node.set_selection_state(SelectionState::None);
return IterationDecision::Continue;
});
}
void InitialContainingBlock::set_selection(LayoutRange const& selection)
{
m_selection = selection;
recompute_selection_states();
}
// 2. If there is no active Selection or selected Range, return.
auto selection = document().get_selection();
if (!selection)
return;
auto range = selection->range();
if (!range)
return;
void InitialContainingBlock::set_selection_end(LayoutPosition const& position)
{
m_selection.set_end(position);
recompute_selection_states();
auto* start_container = range->start_container();
auto* end_container = range->end_container();
// 3. If the selection starts and ends in the same text node, mark it as StartAndEnd and return.
if (start_container == end_container && is<DOM::Text>(*start_container)) {
if (auto* layout_node = start_container->layout_node()) {
layout_node->set_selection_state(SelectionState::StartAndEnd);
}
return;
}
// 4. Mark the selection start node as Start (if text) or Full (if anything else).
if (auto* layout_node = start_container->layout_node()) {
if (is<DOM::Text>(*start_container))
layout_node->set_selection_state(SelectionState::Start);
else
layout_node->set_selection_state(SelectionState::Full);
}
// 5. Mark the selection end node as End (if text) or Full (if anything else).
if (auto* layout_node = end_container->layout_node()) {
if (is<DOM::Text>(*end_container))
layout_node->set_selection_state(SelectionState::End);
else
layout_node->set_selection_state(SelectionState::Full);
}
// 6. Mark the nodes between start node and end node (in tree order) as Full.
for (auto* node = start_container->next_in_pre_order(); node && node != end_container; node = node->next_in_pre_order()) {
if (auto* layout_node = node->layout_node())
layout_node->set_selection_state(SelectionState::Full);
}
}
}