LibWeb: Implement basics for OffscreenCanvas

This implements the basic interface, classes and functions for OffscreenCanvas. Many are still stubbed out and have many FIXMEs in them, but it is a basic skeleton.
Author: https://github.com/Totto16 Commit: 2ad3ce5d37 Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3788 Reviewed-by: https://github.com/ADKaster ✅ Reviewed-by: https://github.com/tcl3
2025-08-12 19:19:30 +00:00 · 2025-03-07 00:19:45 +01:00 · 2025-03-07 00:19:45 +01:00 · 2ad3ce5d37 · 2025-06-30 15:47:43 +00:00
commit 2ad3ce5d37
parent 193ab3757b
14 changed files with 1094 additions and 4 deletions
--- a/Libraries/LibWeb/HTML/OffscreenCanvasRenderingContext2D.h
+++ b/Libraries/LibWeb/HTML/OffscreenCanvasRenderingContext2D.h
@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2025, Ladybird contributors
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Variant.h>
+#include <LibGfx/AffineTransform.h>
+#include <LibGfx/Color.h>
+#include <LibGfx/Forward.h>
+#include <LibGfx/Painter.h>
+#include <LibGfx/Path.h>
+#include <LibWeb/Bindings/PlatformObject.h>
+#include <LibWeb/DOM/EventTarget.h>
+#include <LibWeb/HTML/Canvas/CanvasCompositing.h>
+#include <LibWeb/HTML/Canvas/CanvasDrawImage.h>
+#include <LibWeb/HTML/Canvas/CanvasDrawPath.h>
+#include <LibWeb/HTML/Canvas/CanvasFillStrokeStyles.h>
+#include <LibWeb/HTML/Canvas/CanvasFilters.h>
+#include <LibWeb/HTML/Canvas/CanvasImageData.h>
+#include <LibWeb/HTML/Canvas/CanvasImageSmoothing.h>
+#include <LibWeb/HTML/Canvas/CanvasPath.h>
+#include <LibWeb/HTML/Canvas/CanvasPathDrawingStyles.h>
+#include <LibWeb/HTML/Canvas/CanvasRect.h>
+#include <LibWeb/HTML/Canvas/CanvasSettings.h>
+#include <LibWeb/HTML/Canvas/CanvasShadowStyles.h>
+#include <LibWeb/HTML/Canvas/CanvasState.h>
+#include <LibWeb/HTML/Canvas/CanvasText.h>
+#include <LibWeb/HTML/Canvas/CanvasTextDrawingStyles.h>
+#include <LibWeb/HTML/Canvas/CanvasTransform.h>
+#include <LibWeb/HTML/CanvasGradient.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
+#include <LibWeb/WebIDL/Types.h>
+
+namespace Web::HTML {
+
+class OffscreenCanvasRenderingContext2D : public Bindings::PlatformObject
+    , public CanvasState
+    , public CanvasTransform<OffscreenCanvasRenderingContext2D>
+    , public CanvasFillStrokeStyles<OffscreenCanvasRenderingContext2D>
+    , public CanvasShadowStyles<OffscreenCanvasRenderingContext2D>
+    , public CanvasFilters
+    , public CanvasRect
+    , public CanvasDrawPath
+    , public CanvasText
+    , public CanvasDrawImage
+    , public CanvasImageData
+    , public CanvasImageSmoothing
+    , public CanvasCompositing
+    , public CanvasSettings
+    , public CanvasPathDrawingStyles<OffscreenCanvasRenderingContext2D>
+    , public CanvasTextDrawingStyles<OffscreenCanvasRenderingContext2D, OffscreenCanvas>
+    , public CanvasPath
+
+{
+    WEB_PLATFORM_OBJECT(OffscreenCanvasRenderingContext2D, Bindings::PlatformObject);
+    GC_DECLARE_ALLOCATOR(OffscreenCanvasRenderingContext2D);
+
+public:
+    [[nodiscard]] static JS::ThrowCompletionOr<GC::Ref<OffscreenCanvasRenderingContext2D>> create(JS::Realm&, OffscreenCanvas&, JS::Value);
+    virtual ~OffscreenCanvasRenderingContext2D() override;
+
+    GC::Ref<OffscreenCanvas> canvas();
+
+    virtual void fill_rect(float x, float y, float width, float height) override;
+    virtual void stroke_rect(float x, float y, float width, float height) override;
+    virtual void clear_rect(float x, float y, float width, float height) override;
+
+    virtual WebIDL::ExceptionOr<void> draw_image_internal(CanvasImageSource const&, float source_x, float source_y, float source_width, float source_height, float destination_x, float destination_y, float destination_width, float destination_height) override;
+
+    virtual void begin_path() override;
+    virtual void stroke() override;
+    virtual void stroke(Path2D const& path) override;
+
+    virtual void fill_text(StringView, float x, float y, Optional<double> max_width) override;
+    virtual void stroke_text(StringView, float x, float y, Optional<double> max_width) override;
+
+    virtual void fill(StringView fill_rule) override;
+    virtual void fill(Path2D& path, StringView fill_rule) override;
+
+    virtual WebIDL::ExceptionOr<GC::Ref<ImageData>> create_image_data(int width, int height, Optional<ImageDataSettings> const& settings = {}) const override;
+    virtual WebIDL::ExceptionOr<GC::Ref<ImageData>> create_image_data(ImageData const& image_data) const override;
+    virtual WebIDL::ExceptionOr<GC::Ptr<ImageData>> get_image_data(int x, int y, int width, int height, Optional<ImageDataSettings> const& settings = {}) const override;
+    virtual void put_image_data(ImageData&, float x, float y) override;
+
+    virtual void reset_to_default_state() override;
+
+    virtual CanvasRenderingContext2DSettings get_context_attributes() const override { return m_context_attributes; }
+
+    virtual GC::Ref<TextMetrics> measure_text(StringView text) override;
+
+    virtual void clip(StringView fill_rule) override;
+    virtual void clip(Path2D& path, StringView fill_rule) override;
+
+    virtual bool is_point_in_path(double x, double y, StringView fill_rule) override;
+    virtual bool is_point_in_path(Path2D const& path, double x, double y, StringView fill_rule) override;
+
+    virtual bool image_smoothing_enabled() const override;
+    virtual void set_image_smoothing_enabled(bool) override;
+    virtual Bindings::ImageSmoothingQuality image_smoothing_quality() const override;
+    virtual void set_image_smoothing_quality(Bindings::ImageSmoothingQuality) override;
+
+    virtual float global_alpha() const override;
+    virtual void set_global_alpha(float) override;
+
+    virtual String global_composite_operation() const override;
+    virtual void set_global_composite_operation(String) override;
+
+    virtual String filter() const override;
+    virtual void set_filter(String) override;
+
+    virtual float shadow_offset_x() const override;
+    virtual void set_shadow_offset_x(float) override;
+    virtual float shadow_offset_y() const override;
+    virtual void set_shadow_offset_y(float) override;
+    virtual float shadow_blur() const override;
+    virtual void set_shadow_blur(float) override;
+    virtual String shadow_color() const override;
+    virtual void set_shadow_color(String) override;
+
+    OffscreenCanvas& canvas_element();
+    OffscreenCanvas const& canvas_element() const;
+
+    [[nodiscard]] Gfx::Painter* painter();
+
+    void set_size(Gfx::IntSize const&);
+
+private:
+    explicit OffscreenCanvasRenderingContext2D(JS::Realm&, OffscreenCanvas&, CanvasRenderingContext2DSettings);
+
+    virtual void initialize(JS::Realm&) override;
+    virtual void visit_edges(Cell::Visitor&) override;
+
+    virtual Gfx::Painter* painter_for_canvas_state() override
+    {
+        dbgln("(STUBBED) OffscreenCanvasRenderingContext2D::painter_for_canvas_state()");
+        return nullptr;
+    }
+    virtual Gfx::Path& path_for_canvas_state() override { return path(); }
+
+    GC::Ref<OffscreenCanvas> m_canvas;
+    Gfx::IntSize m_size;
+    CanvasRenderingContext2DSettings m_context_attributes;
+};
+
+}