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LibWeb: Use width & height to create fallback viewBox for SVG-as-image

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When embedding an SVG in an img element, if the external SVG's root
element has both width and height attributes, but no viewBox attribute,
we now create a fallback viewBox with "0 0 width height".

This appears to match the behavior of other browsers. Inspired by
discussion on Mozilla's bug tracker:
https://bugzilla.mozilla.org/show_bug.cgi?id=614649
This commit is contained in:
Andreas Kling 2023-06-20 09:39:14 +02:00
parent a0b4987e92
commit 9f24c1b34c
Notes: sideshowbarker 2024-07-17 00:57:24 +09:00
6 changed files with 66 additions and 2 deletions
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8
Tests/LibWeb/Layout/expected/svg/svg-as-image-implicit-viewbox.txt Normal file
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@ -0,0 +1,8 @@
Viewport <#document> at (0,0) content-size 800x600 children: not-inline
BlockContainer <html> at (0,0) content-size 800x116 [BFC] children: not-inline
BlockContainer <body> at (8,8) content-size 784x100 children: not-inline
ImageBox <img> at (8,8) content-size 50x100 children: not-inline
(SVG-as-image isolated context)
Viewport <#document> at (0,0) content-size 50x100 children: inline
SVGSVGBox <svg> at (0,0) content-size 50x100 [SVG] children: not-inline
SVGGeometryBox <rect> at (0,0) content-size 50x100 children: not-inline

1
Tests/LibWeb/Layout/input/svg/svg-as-image-implicit-viewbox.html Normal file
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@ -0,0 +1 @@
<!doctype html><img src="svg-without-viewbox.svg" style="display: block; width: 50px;">

1
Tests/LibWeb/Layout/input/svg/svg-without-viewbox.svg Normal file
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@ -0,0 +1 @@
<svg width="100" height="200" xmlns="http://www.w3.org/2000/svg"><rect x="0" y="0" width="100" height="200" fill="green" /></svg>
Side by side

After

Width:  |  Height:  |  Size: 129 B

2
Userland/Libraries/LibWeb/Layout/SVGFormattingContext.cpp
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@ -159,7 +159,7 @@ void SVGFormattingContext::run(Box const& box, LayoutMode layout_mode, Available
auto path_transform = dom_node.get_transform();
double viewbox_scale = 1;
auto& maybe_view_box = svg_svg_element.view_box();
auto maybe_view_box = svg_svg_element.view_box();
if (maybe_view_box.has_value()) {
// FIXME: This should allow just one of width or height to be specified.
// E.g. We should be able to layout <svg width="100%"> where height is unspecified/auto.

48
Userland/Libraries/LibWeb/SVG/SVGSVGElement.cpp
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@ -7,6 +7,7 @@
#include <LibWeb/CSS/Parser/Parser.h>
#include <LibWeb/CSS/StyleComputer.h>
#include <LibWeb/CSS/StyleValues/LengthStyleValue.h>
#include <LibWeb/CSS/StyleValues/PercentageStyleValue.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Event.h>
@ -77,6 +78,53 @@ void SVGSVGElement::parse_attribute(DeprecatedFlyString const& name, DeprecatedS
m_view_box = try_parse_view_box(value);
if (name.equals_ignoring_ascii_case(SVG::AttributeNames::preserveAspectRatio))
m_preserve_aspect_ratio = AttributeParser::parse_preserve_aspect_ratio(value);
if (name.equals_ignoring_ascii_case(SVG::AttributeNames::width) || name.equals_ignoring_ascii_case(SVG::AttributeNames::height))
update_fallback_view_box_for_svg_as_image();
}
void SVGSVGElement::update_fallback_view_box_for_svg_as_image()
{
// AD-HOC: This creates a fallback viewBox for SVGs used as images.
// If the <svg> element has width and height, but no viewBox,
// we fall back to a synthetic viewBox="0 0 width height".
Optional<double> width;
Optional<double> height;
auto width_attribute = attribute(SVG::AttributeNames::width);
auto parsing_context = CSS::Parser::ParsingContext { document() };
if (auto width_value = parse_css_value(parsing_context, attribute(Web::HTML::AttributeNames::width), CSS::PropertyID::Width).release_value_but_fixme_should_propagate_errors()) {
if (width_value->is_length() && width_value->as_length().length().is_absolute())
width = width_value->as_length().length().absolute_length_to_px().to_double();
}
auto height_attribute = attribute(SVG::AttributeNames::height);
if (auto height_value = parse_css_value(parsing_context, attribute(Web::HTML::AttributeNames::height), CSS::PropertyID::Height).release_value_but_fixme_should_propagate_errors()) {
if (height_value->is_length() && height_value->as_length().length().is_absolute())
height = height_value->as_length().length().absolute_length_to_px().to_double();
}
if (width.has_value() && height.has_value()) {
m_fallback_view_box_for_svg_as_image = ViewBox { 0, 0, width.value(), height.value() };
} else {
m_fallback_view_box_for_svg_as_image = {};
}
}
void SVGSVGElement::set_fallback_view_box_for_svg_as_image(Optional<ViewBox> view_box)
{
m_fallback_view_box_for_svg_as_image = view_box;
}
Optional<ViewBox> SVGSVGElement::view_box() const
{
if (m_view_box.has_value())
return m_view_box;
if (m_fallback_view_box_for_svg_as_image.has_value())
return m_fallback_view_box_for_svg_as_image;
return {};
}
}

8
Userland/Libraries/LibWeb/SVG/SVGSVGElement.h
View file

@ -24,9 +24,11 @@ public:
virtual bool requires_svg_container() const override { return false; }
virtual bool is_svg_container() const override { return true; }
Optional<ViewBox> const& view_box() const { return m_view_box; }
[[nodiscard]] Optional<ViewBox> view_box() const;
Optional<PreserveAspectRatio> const& preserve_aspect_ratio() const { return m_preserve_aspect_ratio; }
void set_fallback_view_box_for_svg_as_image(Optional<ViewBox>);
private:
SVGSVGElement(DOM::Document&, DOM::QualifiedName);
@ -36,8 +38,12 @@ private:
virtual void parse_attribute(DeprecatedFlyString const& name, DeprecatedString const& value) override;
void update_fallback_view_box_for_svg_as_image();
Optional<ViewBox> m_view_box;
Optional<PreserveAspectRatio> m_preserve_aspect_ratio;
Optional<ViewBox> m_fallback_view_box_for_svg_as_image;
};
}