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LibWeb: Account for scroll offset in hit-testing

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The hit-testing position is now shifted by the scroll offsets before
performing any checks for containment. This is implemented by assigning
each PaintableBox/InlinePaintable an offset corresponding to the scroll
frame in which it is contained. The non-scroll-adjusted position is
still passed down when recursing to children because the assigned
offset accumulated for nested scroll frames.

With this change, hit testing works in the Inspector.
Fixes https://github.com/SerenityOS/serenity/issues/22068
This commit is contained in:
Aliaksandr Kalenik 2024-01-29 06:28:17 +01:00 • committed by Andreas Kling
parent beb1c85b6b
commit 556679fedd
7 changed files with 81 additions and 10 deletions
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24
Userland/Libraries/LibWeb/Painting/PaintableBox.cpp
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@ -672,6 +672,10 @@ Layout::BlockContainer& PaintableWithLines::layout_box()
Optional<HitTestResult> PaintableBox::hit_test(CSSPixelPoint position, HitTestType type) const
{
auto position_adjusted_by_scroll_offset = position;
if (enclosing_scroll_frame_offset().has_value())
position_adjusted_by_scroll_offset.translate_by(-enclosing_scroll_frame_offset().value());
if (!is_visible())
return {};
@ -680,7 +684,7 @@ Optional<HitTestResult> PaintableBox::hit_test(CSSPixelPoint position, HitTestTy
return stacking_context()->hit_test(position, type);
}
if (!absolute_border_box_rect().contains(position.x(), position.y()))
if (!absolute_border_box_rect().contains(position_adjusted_by_scroll_offset.x(), position_adjusted_by_scroll_offset.y()))
return {};
for (auto* child = first_child(); child; child = child->next_sibling()) {
@ -700,6 +704,10 @@ Optional<HitTestResult> PaintableBox::hit_test(CSSPixelPoint position, HitTestTy
Optional<HitTestResult> PaintableWithLines::hit_test(CSSPixelPoint position, HitTestType type) const
{
auto position_adjusted_by_scroll_offset = position;
if (enclosing_scroll_frame_offset().has_value())
position_adjusted_by_scroll_offset.translate_by(-enclosing_scroll_frame_offset().value());
if (!layout_box().children_are_inline() || m_fragments.is_empty())
return PaintableBox::hit_test(position, type);
@ -717,10 +725,10 @@ Optional<HitTestResult> PaintableWithLines::hit_test(CSSPixelPoint position, Hit
if (fragment.paintable().stacking_context())
continue;
auto fragment_absolute_rect = fragment.absolute_rect();
if (fragment_absolute_rect.contains(position)) {
if (fragment_absolute_rect.contains(position_adjusted_by_scroll_offset)) {
if (auto result = fragment.paintable().hit_test(position, type); result.has_value())
return result;
return HitTestResult { const_cast<Paintable&>(fragment.paintable()), fragment.text_index_at(position.x()) };
return HitTestResult { const_cast<Paintable&>(fragment.paintable()), fragment.text_index_at(position_adjusted_by_scroll_offset.x()) };
}
// If we reached this point, the position is not within the fragment. However, the fragment start or end might be the place to place the cursor.
@ -728,11 +736,11 @@ Optional<HitTestResult> PaintableWithLines::hit_test(CSSPixelPoint position, Hit
// The best candidate is either the end of the line above, the beginning of the line below, or the beginning or end of the current line.
// We arbitrarily choose to consider the end of the line above and ignore the beginning of the line below.
// If we knew the direction of selection, we could make a better choice.
if (fragment_absolute_rect.bottom() - 1 <= position.y()) { // fully below the fragment
if (fragment_absolute_rect.bottom() - 1 <= position_adjusted_by_scroll_offset.y()) { // fully below the fragment
last_good_candidate = HitTestResult { const_cast<Paintable&>(fragment.paintable()), fragment.start() + fragment.length() };
} else if (fragment_absolute_rect.top() <= position.y()) { // vertically within the fragment
if (position.x() < fragment_absolute_rect.left()) { // left of the fragment
if (!last_good_candidate.has_value()) { // first fragment of the line
} else if (fragment_absolute_rect.top() <= position_adjusted_by_scroll_offset.y()) { // vertically within the fragment
if (position_adjusted_by_scroll_offset.x() < fragment_absolute_rect.left()) { // left of the fragment
if (!last_good_candidate.has_value()) { // first fragment of the line
last_good_candidate = HitTestResult { const_cast<Paintable&>(fragment.paintable()), fragment.start() };
}
} else { // right of the fragment
@ -743,7 +751,7 @@ Optional<HitTestResult> PaintableWithLines::hit_test(CSSPixelPoint position, Hit
if (type == HitTestType::TextCursor && last_good_candidate.has_value())
return last_good_candidate;
if (is_visible() && absolute_border_box_rect().contains(position.x(), position.y()))
if (is_visible() && absolute_border_box_rect().contains(position_adjusted_by_scroll_offset.x(), position_adjusted_by_scroll_offset.y()))
return HitTestResult { const_cast<PaintableWithLines&>(*this) };
return {};
}