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LibWeb: Update hit_test for CSS Transforms

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This now also takes a FloatPoint instead of an IntPoint to avoid
excessive rounding when multiple transforms apply on top of each other.
This commit is contained in:
Simon Wanner 2022-03-18 01:32:50 +01:00 • committed by Andreas Kling
parent a2331e8dd3
commit 48efdaa8c4
7 changed files with 28 additions and 23 deletions
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21
Userland/Libraries/LibWeb/Painting/StackingContext.cpp
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@ -272,8 +272,13 @@ void StackingContext::paint(PaintContext& context) const
}
}
HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestType type) const
HitTestResult StackingContext::hit_test(Gfx::FloatPoint const& position, HitTestType type) const
{
// FIXME: Use the transform origin specified in CSS or SVG
auto transform_origin = m_box.paint_box()->absolute_position();
auto affine_transform = combine_transformations_2d(m_box.computed_values().transformations());
auto transformed_position = affine_transform.inverse().value_or({}).map(position - transform_origin) + transform_origin;
// NOTE: Hit testing basically happens in reverse painting order.
// https://www.w3.org/TR/CSS22/visuren.html#z-index
@ -282,7 +287,7 @@ HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestTy
auto const& child = *m_children[i];
if (child.m_box.computed_values().z_index().value_or(0) < 0)
break;
auto result = child.hit_test(position, type);
auto result = child.hit_test(transformed_position, type);
if (result.paintable)
return result;
}
@ -291,7 +296,7 @@ HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestTy
// 6. the child stacking contexts with stack level 0 and the positioned descendants with stack level 0.
m_box.for_each_in_subtree_of_type<Layout::Box>([&](Layout::Box const& box) {
if (box.is_positioned() && !box.paint_box()->stacking_context()) {
result = box.paint_box()->hit_test(position, type);
result = box.paint_box()->hit_test(transformed_position, type);
if (result.paintable)
return IterationDecision::Break;
}
@ -302,7 +307,7 @@ HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestTy
// 5. the in-flow, inline-level, non-positioned descendants, including inline tables and inline blocks.
if (m_box.children_are_inline() && is<Layout::BlockContainer>(m_box)) {
auto result = m_box.paint_box()->hit_test(position, type);
auto result = m_box.paint_box()->hit_test(transformed_position, type);
if (result.paintable)
return result;
}
@ -310,7 +315,7 @@ HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestTy
// 4. the non-positioned floats.
m_box.for_each_in_subtree_of_type<Layout::Box>([&](Layout::Box const& box) {
if (box.is_floating()) {
result = box.paint_box()->hit_test(position, type);
result = box.paint_box()->hit_test(transformed_position, type);
if (result.paintable)
return IterationDecision::Break;
}
@ -321,7 +326,7 @@ HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestTy
if (!m_box.children_are_inline()) {
m_box.for_each_in_subtree_of_type<Layout::Box>([&](Layout::Box const& box) {
if (!box.is_absolutely_positioned() && !box.is_floating()) {
result = box.paint_box()->hit_test(position, type);
result = box.paint_box()->hit_test(transformed_position, type);
if (result.paintable)
return IterationDecision::Break;
}
@ -336,13 +341,13 @@ HitTestResult StackingContext::hit_test(Gfx::IntPoint const& position, HitTestTy
auto const& child = *m_children[i];
if (child.m_box.computed_values().z_index().value_or(0) < 0)
break;
auto result = child.hit_test(position, type);
auto result = child.hit_test(transformed_position, type);
if (result.paintable)
return result;
}
// 1. the background and borders of the element forming the stacking context.
if (m_box.paint_box()->absolute_border_box_rect().contains(position.to_type<float>())) {
if (m_box.paint_box()->absolute_border_box_rect().contains(transformed_position)) {
return HitTestResult {
.paintable = m_box.paintable(),
};