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61 lines
3 KiB
C++
61 lines
3 KiB
C++
/*
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* Copyright (c) 2024, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibWeb/CSS/StyleInvalidation.h>
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#include <LibWeb/CSS/StyleProperties.h>
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namespace Web::CSS {
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RequiredInvalidationAfterStyleChange compute_property_invalidation(CSS::PropertyID property_id, RefPtr<CSSStyleValue const> const& old_value, RefPtr<CSSStyleValue const> const& new_value)
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{
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RequiredInvalidationAfterStyleChange invalidation;
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bool const property_value_changed = (!old_value || !new_value) || *old_value != *new_value;
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if (!property_value_changed)
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return invalidation;
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// NOTE: If the computed CSS display, content, or content-visibility property changes, we have to rebuild the entire layout tree.
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// In the future, we should figure out ways to rebuild a smaller part of the tree.
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if (AK::first_is_one_of(property_id, CSS::PropertyID::Display, CSS::PropertyID::Content, CSS::PropertyID::ContentVisibility)) {
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return RequiredInvalidationAfterStyleChange::full();
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}
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// NOTE: If one of the overflow properties change, we rebuild the entire layout tree.
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// This ensures that overflow propagation from root/body to viewport happens correctly.
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// In the future, we can make this invalidation narrower.
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if (property_id == CSS::PropertyID::OverflowX || property_id == CSS::PropertyID::OverflowY) {
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return RequiredInvalidationAfterStyleChange::full();
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}
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// OPTIMIZATION: Special handling for CSS `visibility`:
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if (property_id == CSS::PropertyID::Visibility) {
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// We don't need to relayout if the visibility changes from visible to hidden or vice versa. Only collapse requires relayout.
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if ((old_value && old_value->to_keyword() == CSS::Keyword::Collapse) != (new_value && new_value->to_keyword() == CSS::Keyword::Collapse))
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invalidation.relayout = true;
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// Of course, we still have to repaint on any visibility change.
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invalidation.repaint = true;
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} else if (CSS::property_affects_layout(property_id)) {
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invalidation.relayout = true;
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}
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if (property_id == CSS::PropertyID::Opacity && old_value && new_value) {
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// OPTIMIZATION: An element creates a stacking context when its opacity changes from 1 to less than 1
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// and stops to create one when opacity returns to 1. So stacking context tree rebuild is
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// not required for opacity changes within the range below 1.
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auto old_value_opacity = CSS::StyleProperties::resolve_opacity_value(*old_value);
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auto new_value_opacity = CSS::StyleProperties::resolve_opacity_value(*new_value);
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if (old_value_opacity != new_value_opacity && (old_value_opacity == 1 || new_value_opacity == 1)) {
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invalidation.rebuild_stacking_context_tree = true;
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}
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} else if (CSS::property_affects_stacking_context(property_id)) {
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invalidation.rebuild_stacking_context_tree = true;
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}
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invalidation.repaint = true;
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return invalidation;
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}
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}
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