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LibWeb: Resolve CSS transform properties during layout commit

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Now, instead of resolving "transform" and "transform-origin" during the
construction of the stacking context tree, we do so during the layout
commit.

This is part of a refactoring effort to make the paintable tree
independent from the layout tree.
This commit is contained in:
Aliaksandr Kalenik 2024-01-16 19:54:05 +01:00 • committed by Andreas Kling
parent aab3cd33f6
commit ef0c390b79
5 changed files with 57 additions and 42 deletions
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51
Userland/Libraries/LibWeb/Painting/StackingContext.cpp
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@ -33,8 +33,6 @@ static void paint_node(Paintable const& paintable, PaintContext& context, PaintP
StackingContext::StackingContext(Paintable& paintable, StackingContext* parent, size_t index_in_tree_order)
: m_paintable(paintable)
, m_transform(combine_transformations(paintable.computed_values().transformations()))
, m_transform_origin(compute_transform_origin())
, m_parent(parent)
, m_index_in_tree_order(index_in_tree_order)
{
@ -291,28 +289,13 @@ void StackingContext::paint_internal(PaintContext& context) const
}
}
Gfx::FloatMatrix4x4 StackingContext::combine_transformations(Vector<CSS::Transformation> const& transformations) const
{
// https://drafts.csswg.org/css-transforms-1/#WD20171130 says:
// "No transform on non-replaced inline boxes, table-column boxes, and table-column-group boxes."
// and https://www.w3.org/TR/css-transforms-2/ does not say anything about what to do with inline boxes.
auto matrix = Gfx::FloatMatrix4x4::identity();
if (paintable().is_paintable_box()) {
for (auto const& transform : transformations)
matrix = matrix * transform.to_matrix(paintable_box()).release_value();
return matrix;
}
return matrix;
}
// FIXME: This extracts the affine 2D part of the full transformation matrix.
// Use the whole matrix when we get better transformation support in LibGfx or use LibGL for drawing the bitmap
Gfx::AffineTransform StackingContext::affine_transform_matrix() const
{
return Gfx::extract_2d_affine_transform(m_transform);
if (paintable().is_paintable_box())
return Gfx::extract_2d_affine_transform(paintable_box().transform());
return Gfx::AffineTransform {};
}
static Gfx::FloatMatrix4x4 matrix_with_scaled_translation(Gfx::FloatMatrix4x4 matrix, float scale)
@ -342,14 +325,21 @@ void StackingContext::paint(PaintContext& context) const
VERIFY_NOT_REACHED();
}
auto transform_matrix = Gfx::FloatMatrix4x4::identity();
Gfx::FloatPoint transform_origin;
if (paintable().is_paintable_box()) {
transform_matrix = paintable_box().transform();
transform_origin = paintable_box().transform_origin().to_type<float>();
}
RecordingPainter::PushStackingContextParams push_stacking_context_params {
.opacity = opacity,
.is_fixed_position = paintable().is_fixed_position(),
.source_paintable_rect = source_paintable_rect,
.image_rendering = paintable().computed_values().image_rendering(),
.transform = {
.origin = transform_origin().scaled(to_device_pixels_scale),
.matrix = matrix_with_scaled_translation(transform_matrix(), to_device_pixels_scale),
.origin = transform_origin.scaled(to_device_pixels_scale),
.matrix = matrix_with_scaled_translation(transform_matrix, to_device_pixels_scale),
},
};
@ -374,19 +364,6 @@ void StackingContext::paint(PaintContext& context) const
context.recording_painter().pop_stacking_context();
}
Gfx::FloatPoint StackingContext::compute_transform_origin() const
{
if (!paintable().is_paintable_box())
return {};
auto style_value = paintable().computed_values().transform_origin();
// FIXME: respect transform-box property
auto reference_box = paintable_box().absolute_border_box_rect();
auto x = reference_box.left() + style_value.x.to_px(paintable().layout_node(), reference_box.width());
auto y = reference_box.top() + style_value.y.to_px(paintable().layout_node(), reference_box.height());
return { x.to_float(), y.to_float() };
}
template<typename Callback>
static TraversalDecision for_each_in_inclusive_subtree_within_same_stacking_context_in_reverse(Paintable const& paintable, Callback callback)
{
@ -420,7 +397,9 @@ Optional<HitTestResult> StackingContext::hit_test(CSSPixelPoint position, HitTes
if (!paintable().is_visible())
return {};
auto transform_origin = this->transform_origin().to_type<CSSPixels>();
CSSPixelPoint transform_origin { 0, 0 };
if (paintable().is_paintable_box())
transform_origin = paintable_box().transform_origin();
// NOTE: This CSSPixels -> Float -> CSSPixels conversion is because we can't AffineTransform::map() a CSSPixelPoint.
Gfx::FloatPoint offset_position {
(position.x() - transform_origin.x()).to_float(),