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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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60
Userland/Libraries/LibWeb/SVG/SVGRadialGradientElement.cpp
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@ -52,13 +52,19 @@ void SVGRadialGradientElement::attribute_changed(FlyString const& name, Optional
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementFXAttribute
NumberPercentage SVGRadialGradientElement::start_circle_x() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return start_circle_x_impl(seen_gradients);
}
NumberPercentage SVGRadialGradientElement::start_circle_x_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_fx.has_value())
return *m_fx;
// If the element references an element that specifies a value for 'fx', then the value of 'fx' is
// inherited from the referenced element.
if (auto gradient = linked_radial_gradient())
return gradient->start_circle_x();
if (auto gradient = linked_radial_gradient(seen_gradients))
return gradient->start_circle_x_impl(seen_gradients);
// If attribute ‘fx’ is not specified, ‘fx’ will coincide with the presentational value of ‘cx’ for
// the element whether the value for 'cx' was inherited or not.
return end_circle_x();
@ -66,13 +72,19 @@ NumberPercentage SVGRadialGradientElement::start_circle_x() const
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementFYAttribute
NumberPercentage SVGRadialGradientElement::start_circle_y() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return start_circle_y_impl(seen_gradients);
}
NumberPercentage SVGRadialGradientElement::start_circle_y_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_fy.has_value())
return *m_fy;
// If the element references an element that specifies a value for 'fy', then the value of 'fy' is
// inherited from the referenced element.
if (auto gradient = linked_radial_gradient())
return gradient->start_circle_y();
if (auto gradient = linked_radial_gradient(seen_gradients))
return gradient->start_circle_y_impl(seen_gradients);
// If attribute ‘fy’ is not specified, ‘fy’ will coincide with the presentational value of ‘cy’ for
// the element whether the value for 'cy' was inherited or not.
return end_circle_y();
@ -80,46 +92,70 @@ NumberPercentage SVGRadialGradientElement::start_circle_y() const
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementFRAttribute
NumberPercentage SVGRadialGradientElement::start_circle_radius() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return start_circle_radius_impl(seen_gradients);
}
NumberPercentage SVGRadialGradientElement::start_circle_radius_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
// Note: A negative value is an error.
if (m_fr.has_value() && m_fr->value() >= 0)
return *m_fr;
// if the element references an element that specifies a value for 'fr', then the value of
// 'fr' is inherited from the referenced element.
if (auto gradient = linked_radial_gradient())
return gradient->start_circle_radius();
if (auto gradient = linked_radial_gradient(seen_gradients))
return gradient->start_circle_radius_impl(seen_gradients);
// If the attribute is not specified, the effect is as if a value of '0%' were specified.
return NumberPercentage::create_percentage(0);
}
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementCXAttribute
NumberPercentage SVGRadialGradientElement::end_circle_x() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return end_circle_x_impl(seen_gradients);
}
NumberPercentage SVGRadialGradientElement::end_circle_x_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_cx.has_value())
return *m_cx;
if (auto gradient = linked_radial_gradient())
return gradient->end_circle_x();
if (auto gradient = linked_radial_gradient(seen_gradients))
return gradient->end_circle_x_impl(seen_gradients);
return NumberPercentage::create_percentage(50);
}
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementCYAttribute
NumberPercentage SVGRadialGradientElement::end_circle_y() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return end_circle_y_impl(seen_gradients);
}
NumberPercentage SVGRadialGradientElement::end_circle_y_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
if (m_cy.has_value())
return *m_cy;
if (auto gradient = linked_radial_gradient())
return gradient->end_circle_y();
if (auto gradient = linked_radial_gradient(seen_gradients))
return gradient->end_circle_y_impl(seen_gradients);
return NumberPercentage::create_percentage(50);
}
// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementRAttribute
NumberPercentage SVGRadialGradientElement::end_circle_radius() const
{
HashTable<SVGGradientElement const*> seen_gradients;
return end_circle_radius_impl(seen_gradients);
}
NumberPercentage SVGRadialGradientElement::end_circle_radius_impl(HashTable<SVGGradientElement const*>& seen_gradients) const
{
// Note: A negative value is an error.
if (m_r.has_value() && m_r->value() >= 0)
return *m_r;
if (auto gradient = linked_radial_gradient())
return gradient->end_circle_radius();
if (auto gradient = linked_radial_gradient(seen_gradients))
return gradient->end_circle_radius_impl(seen_gradients);
return NumberPercentage::create_percentage(50);
}