LibWeb: Render SVG-as-image into an isolated top-level browsing context

In order to separate the SVG content from the rest of the engine, it
gets its very own Page, PageClient, top-level browsing context, etc.

Unfortunately, we do have to get the palette and CSS/device pixel ratios
from the host Page for now, maybe that's something we could refactor in
the future.

Note that this doesn't work visually yet, since we don't calculate the
intrinsic sizes & ratio for SVG images. That comes next. :^)

Userland/Libraries/LibWeb/HTML/HTMLImageElement.cpp

@@ -29,6 +29,7 @@
 #include <LibWeb/Loader/ResourceLoader.h>
 #include <LibWeb/Painting/PaintableBox.h>
 #include <LibWeb/Platform/ImageCodecPlugin.h>
+#include <LibWeb/SVG/SVGDecodedImageData.h>
 
 namespace Web::HTML {
 
@@ -545,6 +546,22 @@ void HTMLImageElement::handle_successful_fetch(AK::URL const& url_string, ImageR
         m_load_event_delayer.clear();
     };
 
+    // FIXME: Look at the MIME type instead!
+    bool is_svg_image = url_string.basename().ends_with(".svg"sv);
+
+    RefPtr<DecodedImageData> image_data;
+
+    if (is_svg_image) {
+        VERIFY(document().page());
+        auto result = SVG::SVGDecodedImageData::create(*document().page(), url_string, data);
+        if (result.is_error()) {
+            dbgln("Failed to decode SVG image: {}", result.error());
+            dispatch_event(DOM::Event::create(realm(), HTML::EventNames::error).release_value_but_fixme_should_propagate_errors());
+            return;
+        }
+
+        image_data = result.release_value();
+    } else {
         auto result = Web::Platform::ImageCodecPlugin::the().decode_image(data.bytes());
         if (!result.has_value()) {
             dispatch_event(DOM::Event::create(realm(), HTML::EventNames::error).release_value_but_fixme_should_propagate_errors());
@@ -558,8 +575,9 @@ void HTMLImageElement::handle_successful_fetch(AK::URL const& url_string, ImageR
                 .duration = static_cast<int>(frame.duration),
             });
         }
+        image_data = AnimatedBitmapDecodedImageData::create(move(frames), result.value().loop_count, result.value().is_animated).release_value_but_fixme_should_propagate_errors();
+    }
 
-    auto image_data = AnimatedBitmapDecodedImageData::create(move(frames), result.value().loop_count, result.value().is_animated).release_value_but_fixme_should_propagate_errors();
     image_request.set_image_data(image_data);
 
     ListOfAvailableImages::Key key;
@@ -580,7 +598,7 @@ void HTMLImageElement::handle_successful_fetch(AK::URL const& url_string, ImageR
     image_request.set_state(ImageRequest::State::CompletelyAvailable);
 
     // 3. Add the image to the list of available images using the key key, with the ignore higher-layer caching flag set.
-    document().list_of_available_images().add(key, image_data, true).release_value_but_fixme_should_propagate_errors();
+    document().list_of_available_images().add(key, *image_data, true).release_value_but_fixme_should_propagate_errors();
 
     // 4. Fire an event named load at the img element.
     dispatch_event(DOM::Event::create(realm(), HTML::EventNames::load).release_value_but_fixme_should_propagate_errors());

Userland/Libraries/LibWeb/SVG/SVGDecodedImageData.cpp

@@ -5,24 +5,114 @@
  */
 
 #include <LibGfx/Bitmap.h>
+#include <LibWeb/DOM/Document.h>
+#include <LibWeb/Dump.h>
+#include <LibWeb/Fetch/Infrastructure/HTTP/Responses.h>
+#include <LibWeb/HTML/BrowsingContext.h>
+#include <LibWeb/HTML/NavigationParams.h>
+#include <LibWeb/HTML/Parser/HTMLParser.h>
+#include <LibWeb/Layout/Viewport.h>
+#include <LibWeb/Painting/PaintContext.h>
 #include <LibWeb/SVG/SVGDecodedImageData.h>
+#include <LibWeb/SVG/SVGSVGElement.h>
 
 namespace Web::SVG {
 
-ErrorOr<NonnullRefPtr<SVGDecodedImageData>> SVGDecodedImageData::create(ByteBuffer)
+class SVGDecodedImageData::SVGPageClient final : public PageClient {
+public:
+    explicit SVGPageClient(Page& host_page)
+        : m_host_page(host_page)
     {
-    return adopt_nonnull_ref_or_enomem(new (nothrow) SVGDecodedImageData());
     }
 
-SVGDecodedImageData::SVGDecodedImageData()
+    virtual ~SVGPageClient() override = default;
+
+    Page& m_host_page;
+    Page* m_svg_page { nullptr };
+
+    virtual Page& page() override { return *m_svg_page; }
+    virtual Page const& page() const override { return *m_svg_page; }
+    virtual bool is_connection_open() const override { return false; }
+    virtual Gfx::Palette palette() const override { return m_host_page.client().palette(); }
+    virtual DevicePixelRect screen_rect() const override { return {}; }
+    virtual float device_pixels_per_css_pixel() const override { return m_host_page.client().device_pixels_per_css_pixel(); }
+    virtual CSS::PreferredColorScheme preferred_color_scheme() const override { return m_host_page.client().preferred_color_scheme(); }
+    virtual void request_file(FileRequest) override { }
+    virtual void paint(DevicePixelRect const&, Gfx::Bitmap&) override { }
+};
+
+ErrorOr<NonnullRefPtr<SVGDecodedImageData>> SVGDecodedImageData::create(Page& host_page, AK::URL const& url, ByteBuffer data)
+{
+    auto page_client = make<SVGPageClient>(host_page);
+    auto page = make<Page>(*page_client);
+    page_client->m_svg_page = page.ptr();
+    auto browsing_context = HTML::BrowsingContext::create_a_new_top_level_browsing_context(*page);
+    auto response = Fetch::Infrastructure::Response::create(browsing_context->vm());
+    response->url_list().append(url);
+    HTML::NavigationParams navigation_params {
+        .id = {},
+        .request = nullptr,
+        .response = response,
+        .origin = HTML::Origin {},
+        .policy_container = HTML::PolicyContainer {},
+        .final_sandboxing_flag_set = HTML::SandboxingFlagSet {},
+        .cross_origin_opener_policy = HTML::CrossOriginOpenerPolicy {},
+        .coop_enforcement_result = HTML::CrossOriginOpenerPolicyEnforcementResult {},
+        .reserved_environment = {},
+        .browsing_context = browsing_context,
+        .navigable = nullptr,
+    };
+    auto document = DOM::Document::create_and_initialize(DOM::Document::Type::HTML, "text/html", move(navigation_params)).release_value_but_fixme_should_propagate_errors();
+    browsing_context->set_active_document(document);
+
+    auto parser = HTML::HTMLParser::create_with_uncertain_encoding(document, data);
+    parser->run(document->url());
+
+    // Perform some DOM surgery to make the SVG root element be the first child of the Document.
+    // FIXME: This is a huge hack until we figure out how to actually parse separate SVG files.
+    auto* svg_root = document->body()->first_child_of_type<SVG::SVGSVGElement>();
+    svg_root->remove();
+    document->remove_all_children();
+
+    MUST(document->append_child(*svg_root));
+
+    return adopt_nonnull_ref_or_enomem(new (nothrow) SVGDecodedImageData(move(page), move(page_client), move(document), move(svg_root)));
+}
+
+SVGDecodedImageData::SVGDecodedImageData(NonnullOwnPtr<Page> page, NonnullOwnPtr<SVGPageClient> page_client, JS::Handle<DOM::Document> document, JS::Handle<SVG::SVGSVGElement> root_element)
+    : m_page(move(page))
+    , m_page_client(move(page_client))
+    , m_document(move(document))
+    , m_root_element(move(root_element))
 {
 }
 
 SVGDecodedImageData::~SVGDecodedImageData() = default;
 
-RefPtr<Gfx::Bitmap const> SVGDecodedImageData::bitmap(size_t, Gfx::IntSize) const
+void SVGDecodedImageData::render(Gfx::IntSize size) const
 {
+    m_document->browsing_context()->set_viewport_rect({ 0, 0, size.width(), size.height() });
+    m_document->update_layout();
+
+    dump_tree(*m_document->layout_node());
+
+    Gfx::Painter painter(*m_bitmap);
+    PaintContext context(painter, m_page_client->palette(), m_page_client->device_pixels_per_css_pixel());
+
+    m_document->layout_node()->paint_all_phases(context);
+}
+
+RefPtr<Gfx::Bitmap const> SVGDecodedImageData::bitmap(size_t, Gfx::IntSize size) const
+{
+    if (size.is_empty())
         return nullptr;
+
+    if (m_bitmap && m_bitmap->size() == size)
+        return m_bitmap;
+
+    m_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, size).release_value_but_fixme_should_propagate_errors();
+    render(size);
+    return m_bitmap;
 }
 
 Optional<CSSPixels> SVGDecodedImageData::intrinsic_width() const

Userland/Libraries/LibWeb/SVG/SVGDecodedImageData.h

@@ -12,7 +12,7 @@ namespace Web::SVG {
 
 class SVGDecodedImageData final : public HTML::DecodedImageData {
 public:
-    static ErrorOr<NonnullRefPtr<SVGDecodedImageData>> create(ByteBuffer encoded_svg);
+    static ErrorOr<NonnullRefPtr<SVGDecodedImageData>> create(Page&, AK::URL const&, ByteBuffer encoded_svg);
     virtual ~SVGDecodedImageData() override;
 
     virtual RefPtr<Gfx::Bitmap const> bitmap(size_t frame_index, Gfx::IntSize) const override;
@@ -28,7 +28,17 @@ public:
     virtual bool is_animated() const override { return false; }
 
 private:
-    SVGDecodedImageData();
+    class SVGPageClient;
+    SVGDecodedImageData(NonnullOwnPtr<Page>, NonnullOwnPtr<SVGPageClient>, JS::Handle<DOM::Document>, JS::Handle<SVG::SVGSVGElement>);
+
+    void render(Gfx::IntSize) const;
+    mutable RefPtr<Gfx::Bitmap> m_bitmap;
+
+    NonnullOwnPtr<Page> m_page;
+    NonnullOwnPtr<SVGPageClient> m_page_client;
+
+    JS::Handle<DOM::Document> m_document;
+    JS::Handle<SVG::SVGSVGElement> m_root_element;
 };
 
 }