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LibWeb: Handle reference cycles in SVG gradient linking

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Since SVG gradients can reference each other, we have to keep track of
visited gradients when traversing the link chain, or we will recurse
infinitely when there's a reference cycle.
This commit is contained in:
Andreas Kling 2024-03-10 12:18:09 +01:00
parent 1b8d8c7bbc
commit 2e0297d703
8 changed files with 155 additions and 36 deletions
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36
Userland/Libraries/LibWeb/SVG/SVGGradientElement.cpp
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@ -34,29 +34,47 @@ void SVGGradientElement::attribute_changed(FlyString const& name, Optional<Strin
}
GradientUnits SVGGradientElement::gradient_units() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return gradient_units_impl(seen_gradients);
}
GradientUnits SVGGradientElement::gradient_units_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_gradient_units.has_value())
return *m_gradient_units;
if (auto gradient = linked_gradient())
return gradient->gradient_units();
if (auto gradient = linked_gradient(seen_gradients))
return gradient->gradient_units_impl(seen_gradients);
return GradientUnits::ObjectBoundingBox;
}
SpreadMethod SVGGradientElement::spread_method() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return spread_method_impl(seen_gradients);
}
SpreadMethod SVGGradientElement::spread_method_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_spread_method.has_value())
return *m_spread_method;
if (auto gradient = linked_gradient())
return gradient->spread_method();
if (auto gradient = linked_gradient(seen_gradients))
return gradient->spread_method_impl(seen_gradients);
return SpreadMethod::Pad;
}
Optional<Gfx::AffineTransform> SVGGradientElement::gradient_transform() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return gradient_transform_impl(seen_gradients);
}
Optional<Gfx::AffineTransform> SVGGradientElement::gradient_transform_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_gradient_transform.has_value())
return m_gradient_transform;
if (auto gradient = linked_gradient())
return gradient->gradient_transform();
if (auto gradient = linked_gradient(seen_gradients))
return gradient->gradient_transform_impl(seen_gradients);
return {};
}
@ -89,7 +107,7 @@ void SVGGradientElement::add_color_stops(Gfx::SVGGradientPaintStyle& paint_style
});
}
JS::GCPtr<SVGGradientElement const> SVGGradientElement::linked_gradient() const
JS::GCPtr<SVGGradientElement const> SVGGradientElement::linked_gradient(HashTable<SVGGradientElement const*>& seen_gradients) const
{
// FIXME: This entire function is an ad-hoc hack!
// It can only resolve #<ids> in the same document.
@ -103,8 +121,12 @@ JS::GCPtr<SVGGradientElement const> SVGGradientElement::linked_gradient() const
auto element = document().get_element_by_id(id.value());
if (!element)
return {};
if (element == this)
return {};
if (!is<SVGGradientElement>(*element))
return {};
if (seen_gradients.set(&verify_cast<SVGGradientElement>(*element)) != AK::HashSetResult::InsertedNewEntry)
return {};
return &verify_cast<SVGGradientElement>(*element);
}
return {};