LibWeb: Store computed SVG path data/transforms in LayoutState

MacDue · kalenikaliaksandr · commit dc9cb449b1fb · 2023-10-30T19:44:54.000+01:00
This removes the awkward hack to recompute the layout transform at paint
time, and makes it possible for path sizes to be computed during layout.

For example, it's possible to use relative units in SVG shapes (e.g.
&lt;rect&gt;), which can be resolved during layout, but would be hard to
resolve again during painting.
diff --git a/Tests/LibWeb/Ref/reference/simple-svg-mask-ref.html b/Tests/LibWeb/Ref/reference/simple-svg-mask-ref.html
@@ -1,4 +1,4 @@
-<svg width="200" viewBox="-10 -10 120 120">
+<svg width="120" viewBox="-10 -10 120 120">
   <rect x="-10" y="-10" width="120" height="120" fill="blue" />
   <rect x="50" y="10" width="40" height="80" fill="red"  />
 </svg>
diff --git a/Tests/LibWeb/Ref/simple-svg-mask.html b/Tests/LibWeb/Ref/simple-svg-mask.html
@@ -1,5 +1,5 @@
 <link rel="match" href="reference/simple-svg-mask-ref.html" />
-<svg width="200" viewBox="-10 -10 120 120">
+<svg width="120" viewBox="-10 -10 120 120">
   <mask id="myMask">
     <!-- Everything under a white pixel will be visible -->
     <rect x="0" y="0" width="100" height="100" fill="white" />
diff --git a/Tests/LibWeb/Ref/svg-alpha-mask.html b/Tests/LibWeb/Ref/svg-alpha-mask.html
@@ -1,5 +1,5 @@
 <link rel="match" href="reference/simple-svg-mask-ref.html" />
-<svg width="200" viewBox="-10 -10 120 120">
+<svg width="120" viewBox="-10 -10 120 120">
   <defs>
     <mask id="myMask" style="mask-type:alpha">
       <!-- Everything solid pixel (alpha=255) will be visible -->
diff --git a/Tests/LibWeb/Ref/svg-mask-in-defs.html b/Tests/LibWeb/Ref/svg-mask-in-defs.html
@@ -1,5 +1,5 @@
 <link rel="match" href="reference/simple-svg-mask-ref.html" />
-<svg width="200" viewBox="-10 -10 120 120">
+<svg width="120" viewBox="-10 -10 120 120">
   <defs>
     <mask id="myMask">
       <!-- Everything under a white pixel will be visible -->
diff --git a/Tests/LibWeb/Ref/svg-mask-maskUnits-userSpaceOnUse.html b/Tests/LibWeb/Ref/svg-mask-maskUnits-userSpaceOnUse.html
@@ -1,5 +1,5 @@
 <link rel="match" href="reference/simple-svg-mask-ref.html" />
-<svg width="200" viewBox="-10 -10 120 120">
+<svg width="120" viewBox="-10 -10 120 120">
   <defs>
     <mask id="myMask" maskUnits="userSpaceOnUse">
       <!-- Everything under a white pixel will be visible -->
diff --git a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
@@ -265,6 +265,11 @@ void LayoutState::commit(Box& root)
                 paintable_with_lines.set_line_boxes(move(used_values.line_boxes));
                 paintables_with_lines.append(paintable_with_lines);
             }
+
+            if (used_values.svg_path_data().has_value() && is<Painting::SVGGeometryPaintable>(paintable_box)) {
+                auto& svg_geometry_paintable = static_cast<Painting::SVGGeometryPaintable&>(paintable_box);
+                svg_geometry_paintable.set_path_data(move(*used_values.svg_path_data()));
+            }
         }
     }
 
diff --git a/Userland/Libraries/LibWeb/Layout/LayoutState.h b/Userland/Libraries/LibWeb/Layout/LayoutState.h
@@ -11,6 +11,7 @@
 #include <LibWeb/Layout/Box.h>
 #include <LibWeb/Layout/LineBox.h>
 #include <LibWeb/Painting/PaintableBox.h>
+#include <LibWeb/Painting/SVGGeometryPaintable.h>
 
 namespace Web::Layout {
 
@@ -123,6 +124,9 @@ struct LayoutState {
         void set_table_cell_coordinates(Painting::PaintableBox::TableCellCoordinates const& table_cell_coordinates) { m_table_cell_coordinates = table_cell_coordinates; }
         auto const& table_cell_coordinates() const { return m_table_cell_coordinates; }
 
+        void set_svg_path_data(Painting::SVGGeometryPaintable::PathData const& svg_path_data) { m_svg_path_data = svg_path_data; }
+        auto& svg_path_data() const { return m_svg_path_data; }
+
     private:
         AvailableSize available_width_inside() const;
         AvailableSize available_height_inside() const;
@@ -146,6 +150,8 @@ struct LayoutState {
 
         Optional<Painting::PaintableBox::BordersDataWithElementKind> m_override_borders_data;
         Optional<Painting::PaintableBox::TableCellCoordinates> m_table_cell_coordinates;
+
+        Optional<Painting::SVGGeometryPaintable::PathData> m_svg_path_data;
     };
 
     // Commits the used values produced by layout and builds a paintable tree.
diff --git a/Userland/Libraries/LibWeb/Layout/SVGFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/SVGFormattingContext.cpp
@@ -173,7 +173,8 @@ void SVGFormattingContext::run(Box const& box, LayoutMode layout_mode, Available
             auto& dom_node = const_cast<SVGGeometryBox&>(geometry_box).dom_node();
 
             auto& path = dom_node.get_path();
-            auto path_transform = dom_node.get_transform();
+            auto svg_transform = dom_node.get_transform();
+            Gfx::AffineTransform viewbox_transform;
 
             double viewbox_scale = 1;
             auto maybe_view_box = dom_node.view_box();
@@ -190,18 +191,21 @@ void SVGFormattingContext::run(Box const& box, LayoutMode layout_mode, Available
 
                 // The initial value for preserveAspectRatio is xMidYMid meet.
                 auto preserve_aspect_ratio = svg_svg_element.preserve_aspect_ratio().value_or(SVG::PreserveAspectRatio {});
-                auto viewbox_transform = scale_and_align_viewbox_content(preserve_aspect_ratio, view_box, { scale_width, scale_height }, svg_box_state);
-                path_transform = Gfx::AffineTransform {}.translate(viewbox_transform.offset.to_type<float>()).scale(viewbox_transform.scale_factor, viewbox_transform.scale_factor).translate({ -view_box.min_x, -view_box.min_y }).multiply(path_transform);
-                viewbox_scale = viewbox_transform.scale_factor;
+                auto viewbox_offset_and_scale = scale_and_align_viewbox_content(preserve_aspect_ratio, view_box, { scale_width, scale_height }, svg_box_state);
+                viewbox_transform = Gfx::AffineTransform {}.translate(viewbox_offset_and_scale.offset.to_type<float>()).scale(viewbox_offset_and_scale.scale_factor, viewbox_offset_and_scale.scale_factor).translate({ -view_box.min_x, -view_box.min_y });
+
+                viewbox_scale = viewbox_offset_and_scale.scale_factor;
             }
 
             // Stroke increases the path's size by stroke_width/2 per side.
+            auto path_transform = Gfx::AffineTransform {}.multiply(viewbox_transform).multiply(svg_transform);
             auto path_bounding_box = path_transform.map(path.bounding_box()).to_type<CSSPixels>();
             CSSPixels stroke_width = CSSPixels::nearest_value_for(static_cast<double>(geometry_box.dom_node().visible_stroke_width()) * viewbox_scale);
             path_bounding_box.inflate(stroke_width, stroke_width);
             geometry_box_state.set_content_offset(path_bounding_box.top_left());
             geometry_box_state.set_content_width(path_bounding_box.width());
             geometry_box_state.set_content_height(path_bounding_box.height());
+            geometry_box_state.set_svg_path_data(Painting::SVGGeometryPaintable::PathData(path, viewbox_transform, svg_transform));
         } else if (is<SVGSVGBox>(descendant)) {
             SVGFormattingContext nested_context(m_state, static_cast<SVGSVGBox const&>(descendant), this);
             nested_context.run(static_cast<SVGSVGBox const&>(descendant), layout_mode, available_space);
diff --git a/Userland/Libraries/LibWeb/Layout/SVGGeometryBox.cpp b/Userland/Libraries/LibWeb/Layout/SVGGeometryBox.cpp
@@ -17,43 +17,6 @@ SVGGeometryBox::SVGGeometryBox(DOM::Document& document, SVG::SVGGeometryElement&
 {
 }
 
-CSSPixelPoint SVGGeometryBox::viewbox_origin() const
-{
-    auto* svg_box = dom_node().shadow_including_first_ancestor_of_type<SVG::SVGSVGElement>();
-    if (!svg_box || !svg_box->view_box().has_value())
-        return { 0, 0 };
-    return { svg_box->view_box().value().min_x, svg_box->view_box().value().min_y };
-}
-
-Optional<Gfx::AffineTransform> SVGGeometryBox::layout_transform(Gfx::AffineTransform additional_svg_transform) const
-{
-    auto& geometry_element = dom_node();
-    auto transform = geometry_element.get_transform();
-    auto* svg_box = geometry_element.shadow_including_first_ancestor_of_type<SVG::SVGSVGElement>();
-    double scaling = 1;
-    auto origin = viewbox_origin().to_type<float>();
-    Gfx::FloatPoint paint_offset = {};
-    if (svg_box && geometry_element.view_box().has_value()) {
-        // Note: SVGFormattingContext has already done the scaling based on the viewbox,
-        // we now have to derive what it was from the original bounding box size.
-        // FIXME: It would be nice if we could store the transform from layout somewhere, so we don't have to solve for it here.
-        auto original_bounding_box = Gfx::AffineTransform {}.translate(-origin).multiply(transform).map(const_cast<SVG::SVGGeometryElement&>(geometry_element).get_path().bounding_box());
-        float stroke_width = geometry_element.visible_stroke_width();
-        original_bounding_box.inflate(stroke_width, stroke_width);
-        // If the transform (or path) results in a empty box we can't display this.
-        if (original_bounding_box.is_empty())
-            return {};
-        auto scaled_width = paintable_box()->content_width().to_double();
-        auto scaled_height = paintable_box()->content_height().to_double();
-        scaling = min(scaled_width / static_cast<double>(original_bounding_box.width()), scaled_height / static_cast<double>(original_bounding_box.height()));
-        auto scaled_bounding_box = original_bounding_box.scaled(scaling, scaling);
-        paint_offset = (paintable_box()->absolute_rect().location() - svg_box->paintable_box()->absolute_rect().location()).to_type<float>() - scaled_bounding_box.location();
-    }
-    // Note: The "additional_svg_transform" is applied during mask painting to transform the mask element to match its target.
-    // It has to be applied while still in the SVG coordinate space.
-    return Gfx::AffineTransform {}.translate(paint_offset).scale(scaling, scaling).translate(-origin).multiply(additional_svg_transform).multiply(transform);
-}
-
 JS::GCPtr<Painting::Paintable> SVGGeometryBox::create_paintable() const
 {
     return Painting::SVGGeometryPaintable::create(*this);
diff --git a/Userland/Libraries/LibWeb/Layout/SVGGeometryBox.h b/Userland/Libraries/LibWeb/Layout/SVGGeometryBox.h
@@ -22,13 +22,9 @@ class SVGGeometryBox final : public SVGGraphicsBox {
     SVG::SVGGeometryElement& dom_node() { return static_cast<SVG::SVGGeometryElement&>(SVGGraphicsBox::dom_node()); }
     SVG::SVGGeometryElement const& dom_node() const { return static_cast<SVG::SVGGeometryElement const&>(SVGGraphicsBox::dom_node()); }
 
-    Optional<Gfx::AffineTransform> layout_transform(Gfx::AffineTransform additional_svg_transform) const;
-
     virtual JS::GCPtr<Painting::Paintable> create_paintable() const override;
 
 private:
-    CSSPixelPoint viewbox_origin() const;
-
     virtual bool is_svg_geometry_box() const final { return true; }
 };
 
diff --git a/Userland/Libraries/LibWeb/Painting/SVGGeometryPaintable.cpp b/Userland/Libraries/LibWeb/Painting/SVGGeometryPaintable.cpp
@@ -30,15 +30,11 @@ Layout::SVGGeometryBox const& SVGGeometryPaintable::layout_box() const
 Optional<HitTestResult> SVGGeometryPaintable::hit_test(CSSPixelPoint position, HitTestType type) const
 {
     auto result = SVGGraphicsPaintable::hit_test(position, type);
-    if (!result.has_value())
+    if (!result.has_value() || !path_data().has_value())
+        return {};
+    auto transformed_bounding_box = path_data()->svg_to_css_pixels_transform().map_to_quad(path_data()->computed_path().bounding_box());
+    if (!transformed_bounding_box.contains(position.to_type<float>()))
         return {};
-    auto& geometry_element = layout_box().dom_node();
-    if (auto transform = layout_box().layout_transform({}); transform.has_value()) {
-        auto transformed_bounding_box = transform->map_to_quad(
-            const_cast<SVG::SVGGeometryElement&>(geometry_element).get_path().bounding_box());
-        if (!transformed_bounding_box.contains(position.to_type<float>()))
-            return {};
-    }
     return result;
 }
 
@@ -56,7 +52,7 @@ static Gfx::Painter::WindingRule to_gfx_winding_rule(SVG::FillRule fill_rule)
 
 void SVGGeometryPaintable::paint(PaintContext& context, PaintPhase phase) const
 {
-    if (!is_visible())
+    if (!is_visible() || !path_data().has_value())
         return;
 
     SVGGraphicsPaintable::paint(context, phase);
@@ -73,17 +69,10 @@ void SVGGeometryPaintable::paint(PaintContext& context, PaintPhase phase) const
     RecordingPainterStateSaver save_painter { context.painter() };
 
     auto offset = context.floored_device_point(svg_element_rect.location()).to_type<int>().to_type<float>();
-
     auto maybe_view_box = geometry_element.view_box();
 
-    auto transform = layout_box().layout_transform(context.svg_transform());
-    if (!transform.has_value())
-        return;
-
-    auto css_scale = context.device_pixels_per_css_pixel();
-    auto paint_transform = Gfx::AffineTransform {}.scale(css_scale, css_scale).multiply(*transform);
-    auto const& original_path = const_cast<SVG::SVGGeometryElement&>(geometry_element).get_path();
-    Gfx::Path path = original_path.copy_transformed(paint_transform);
+    auto paint_transform = path_data()->svg_to_device_pixels_transform(context, context.svg_transform());
+    Gfx::Path path = path_data()->computed_path().copy_transformed(paint_transform);
 
     // Fills are computed as though all subpaths are closed (https://svgwg.org/svg2-draft/painting.html#FillProperties)
     auto closed_path = [&] {
@@ -106,7 +95,7 @@ void SVGGeometryPaintable::paint(PaintContext& context, PaintPhase phase) const
 
     SVG::SVGPaintContext paint_context {
         .viewport = svg_viewport,
-        .path_bounding_box = original_path.bounding_box(),
+        .path_bounding_box = path_data()->computed_path().bounding_box(),
         .transform = paint_transform
     };
 
diff --git a/Userland/Libraries/LibWeb/Painting/SVGGeometryPaintable.h b/Userland/Libraries/LibWeb/Painting/SVGGeometryPaintable.h
@@ -15,6 +15,41 @@ class SVGGeometryPaintable final : public SVGGraphicsPaintable {
     JS_CELL(SVGGeometryPaintable, SVGGraphicsPaintable);
 
 public:
+    class PathData {
+    public:
+        PathData(Gfx::Path path, Gfx::AffineTransform svg_to_viewbox_transform, Gfx::AffineTransform svg_transform)
+            : m_computed_path(move(path))
+            , m_svg_to_viewbox_transform(svg_to_viewbox_transform)
+            , m_svg_transform(svg_transform)
+        {
+        }
+
+        Gfx::Path const& computed_path() const { return m_computed_path; }
+
+        Gfx::AffineTransform const& svg_to_viewbox_transform() const { return m_svg_to_viewbox_transform; }
+
+        Gfx::AffineTransform const& svg_transform() const { return m_svg_transform; }
+
+        Gfx::AffineTransform svg_to_css_pixels_transform(
+            Optional<Gfx::AffineTransform const&> additional_svg_transform = {}) const
+        {
+            return Gfx::AffineTransform {}.multiply(svg_to_viewbox_transform()).multiply(additional_svg_transform.value_or(Gfx::AffineTransform {})).multiply(svg_transform());
+        }
+
+        Gfx::AffineTransform svg_to_device_pixels_transform(
+            PaintContext const& context,
+            Gfx::AffineTransform const& additional_svg_transform) const
+        {
+            auto css_scale = context.device_pixels_per_css_pixel();
+            return Gfx::AffineTransform {}.scale({ css_scale, css_scale }).multiply(svg_to_css_pixels_transform(additional_svg_transform));
+        }
+
+    private:
+        Gfx::Path m_computed_path;
+        Gfx::AffineTransform m_svg_to_viewbox_transform;
+        Gfx::AffineTransform m_svg_transform;
+    };
+
     static JS::NonnullGCPtr<SVGGeometryPaintable> create(Layout::SVGGeometryBox const&);
 
     virtual Optional<HitTestResult> hit_test(CSSPixelPoint, HitTestType) const override;
@@ -23,8 +58,17 @@ class SVGGeometryPaintable final : public SVGGraphicsPaintable {
 
     Layout::SVGGeometryBox const& layout_box() const;
 
+    void set_path_data(PathData path_data)
+    {
+        m_path_data = move(path_data);
+    }
+
+    Optional<PathData> const& path_data() const { return m_path_data; }
+
 protected:
     SVGGeometryPaintable(Layout::SVGGeometryBox const&);
+
+    Optional<PathData> m_path_data = {};
 };
 
 }

Original file line number	Diff line number	Diff line change
`@@ -265,6 +265,11 @@ void LayoutState::commit(Box& root)`
`265`	`265`	`paintable_with_lines.set_line_boxes(move(used_values.line_boxes));`
`266`	`266`	`paintables_with_lines.append(paintable_with_lines);`
`267`	`267`	`}`
	`268`	`+`
	`269`	`+ if (used_values.svg_path_data().has_value() && is<Painting::SVGGeometryPaintable>(paintable_box)) {`
	`270`	`+ auto& svg_geometry_paintable = static_cast<Painting::SVGGeometryPaintable&>(paintable_box);`
	`271`	`+ svg_geometry_paintable.set_path_data(move(*used_values.svg_path_data()));`
	`272`	`+ }`
`268`	`273`	`}`
`269`	`274`	`}`
`270`	`275`