LibWeb: Update CRC2D .fillStyle and .strokeStyle to accept gradients

While doing add some structures to hold these new fill styles and
plumb them over to the painter.

Userland/Libraries/LibWeb/HTML/Canvas/CanvasFillStrokeStyles.h

@@ -2,6 +2,7 @@
  * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2023, MacDue <macdue@dueutil.tech>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -19,27 +20,39 @@ template<typename IncludingClass>
 class CanvasFillStrokeStyles {
 public:
     ~CanvasFillStrokeStyles() = default;
+    using FillOrStrokeStyleVariant = Variant<DeprecatedString, JS::Handle<CanvasGradient>>;
 
-    void set_fill_style(DeprecatedString style)
+    static CanvasState::FillOrStrokeStyle to_canvas_state_fill_or_stoke_style(auto const& style)
+    {
+        return style.visit(
+            [&](DeprecatedString const& string) -> CanvasState::FillOrStrokeStyle {
+                return Gfx::Color::from_string(string).value_or(Color::Black);
+            },
+            [&](JS::Handle<CanvasGradient> gradient) -> CanvasState::FillOrStrokeStyle {
+                return gradient;
+            });
+    }
+
+    void set_fill_style(FillOrStrokeStyleVariant style)
     {
         // FIXME: 2. If the given value is a CanvasPattern object that is marked as not origin-clean, then set this's origin-clean flag to false.
-        my_drawing_state().fill_style = Gfx::Color::from_string(style).value_or(Color::Black);
+        my_drawing_state().fill_style = to_canvas_state_fill_or_stoke_style(style);
     }
 
-    DeprecatedString fill_style() const
+    FillOrStrokeStyleVariant fill_style() const
     {
-        return my_drawing_state().fill_style.to_deprecated_string();
+        return my_drawing_state().fill_style.to_js_fill_or_stoke_style();
     }
 
-    void set_stroke_style(DeprecatedString style)
+    void set_stroke_style(FillOrStrokeStyleVariant style)
     {
         // FIXME: 2. If the given value is a CanvasPattern object that is marked as not origin-clean, then set this's origin-clean flag to false.
-        my_drawing_state().stroke_style = Gfx::Color::from_string(style).value_or(Color::Black);
+        my_drawing_state().stroke_style = to_canvas_state_fill_or_stoke_style(style);
     }
 
-    DeprecatedString stroke_style() const
+    FillOrStrokeStyleVariant stroke_style() const
     {
-        return my_drawing_state().stroke_style.to_deprecated_string();
+        return my_drawing_state().stroke_style.to_js_fill_or_stoke_style();
     }
 
     JS::NonnullGCPtr<CanvasGradient> create_radial_gradient(double x0, double y0, double r0, double x1, double y1, double r1)

Userland/Libraries/LibWeb/HTML/Canvas/CanvasFillStrokeStyles.idl

@@ -3,9 +3,9 @@
 // https://html.spec.whatwg.org/multipage/canvas.html#canvasfillstrokestyles
 interface mixin CanvasFillStrokeStyles {
     // FIXME: Should be `(DOMString or CanvasGradient or CanvasPattern)`
-    attribute DOMString strokeStyle;
+    attribute (DOMString or CanvasGradient) strokeStyle;
     // FIXME: Should be `(DOMString or CanvasGradient or CanvasPattern)`
-    attribute DOMString fillStyle;
+    attribute (DOMString or CanvasGradient) fillStyle;
     CanvasGradient createLinearGradient(double x0, double y0, double x1, double y1);
     CanvasGradient createRadialGradient(double x0, double y0, double r0, double x1, double y1, double r1);
     CanvasGradient createConicGradient(double startAngle, double x, double y);

Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.cpp

@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2023, MacDue <macdue@dueutil.tech>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -39,4 +40,21 @@ bool CanvasState::is_context_lost()
     return m_context_lost;
 }
 
+NonnullRefPtr<Gfx::PaintStyle> CanvasState::FillOrStrokeStyle::to_gfx_paint_style()
+{
+    VERIFY_NOT_REACHED();
+}
+
+Gfx::Color CanvasState::FillOrStrokeStyle::to_color_but_fixme_should_accept_any_paint_style() const
+{
+    return as_color().value_or(Gfx::Color::Black);
+}
+
+Optional<Gfx::Color> CanvasState::FillOrStrokeStyle::as_color() const
+{
+    if (auto* color = m_fill_or_stoke_style.get_pointer<Gfx::Color>())
+        return *color;
+    return {};
+}
+
 }

Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.h

@@ -1,14 +1,18 @@
 /*
  * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2023, MacDue <macdue@dueutil.tech>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
+#include <AK/Variant.h>
 #include <AK/Vector.h>
 #include <LibGfx/AffineTransform.h>
 #include <LibGfx/Color.h>
+#include <LibGfx/PaintStyle.h>
+#include <LibWeb/HTML/CanvasGradient.h>
 
 namespace Web::HTML {
 
@@ -22,11 +26,41 @@ public:
     void reset();
     bool is_context_lost();
 
+    using FillOrStrokeVariant = Variant<Gfx::Color, JS::Handle<CanvasGradient>>;
+
+    struct FillOrStrokeStyle {
+        FillOrStrokeStyle(Gfx::Color color)
+            : m_fill_or_stoke_style(color)
+        {
+        }
+
+        FillOrStrokeStyle(JS::Handle<CanvasGradient> gradient)
+            : m_fill_or_stoke_style(gradient)
+        {
+        }
+
+        NonnullRefPtr<Gfx::PaintStyle> to_gfx_paint_style();
+
+        Optional<Gfx::Color> as_color() const;
+        Gfx::Color to_color_but_fixme_should_accept_any_paint_style() const;
+
+        Variant<DeprecatedString, JS::Handle<CanvasGradient>> to_js_fill_or_stoke_style() const
+        {
+            if (auto* handle = m_fill_or_stoke_style.get_pointer<JS::Handle<CanvasGradient>>())
+                return *handle;
+            return m_fill_or_stoke_style.get<Gfx::Color>().to_deprecated_string();
+        }
+
+    private:
+        FillOrStrokeVariant m_fill_or_stoke_style;
+        RefPtr<Gfx::PaintStyle> m_color_fill_style { nullptr };
+    };
+
     // https://html.spec.whatwg.org/multipage/canvas.html#drawing-state
     struct DrawingState {
         Gfx::AffineTransform transform;
-        Gfx::Color fill_style { Gfx::Color::Black };
-        Gfx::Color stroke_style { Gfx::Color::Black };
+        FillOrStrokeStyle fill_style { Gfx::Color::Black };
+        FillOrStrokeStyle stroke_style { Gfx::Color::Black };
         float line_width { 1 };
     };
     DrawingState& drawing_state() { return m_drawing_state; }

Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp

@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2023, MacDue <macdue@dueutil.tech>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -73,7 +74,13 @@ void CanvasRenderingContext2D::fill_rect(float x, float y, float width, float he
     auto& drawing_state = this->drawing_state();
 
     auto rect = drawing_state.transform.map(Gfx::FloatRect(x, y, width, height));
-    painter->fill_rect(rect, drawing_state.fill_style);
+    auto color_fill = drawing_state.fill_style.as_color();
+    if (color_fill.has_value()) {
+        painter->fill_rect(rect, *color_fill);
+    } else {
+        // FIXME: This should use AntiAliasingPainter::fill_rect() too but that does not support FillPath yet.
+        painter->underlying_painter().fill_rect(rect.to_rounded<int>(), *drawing_state.fill_style.to_gfx_paint_style());
+    }
     did_draw(rect);
 }
 
@@ -109,7 +116,7 @@ void CanvasRenderingContext2D::stroke_rect(float x, float y, float width, float
     path.line_to(bottom_right);
     path.line_to(bottom_left);
     path.line_to(top_left);
-    painter->stroke_path(path, drawing_state.stroke_style, drawing_state.line_width);
+    painter->stroke_path(path, drawing_state.stroke_style.to_color_but_fixme_should_accept_any_paint_style(), drawing_state.line_width);
 
     did_draw(rect);
 }
@@ -211,7 +218,7 @@ void CanvasRenderingContext2D::fill_text(DeprecatedString const& text, float x,
 
     auto text_rect = Gfx::FloatRect(x, y, max_width.has_value() ? static_cast<float>(max_width.value()) : painter->font().width(text), painter->font().pixel_size());
     auto transformed_rect = drawing_state.transform.map(text_rect);
-    painter->draw_text(transformed_rect, text, Gfx::TextAlignment::TopLeft, drawing_state.fill_style);
+    painter->draw_text(transformed_rect, text, Gfx::TextAlignment::TopLeft, drawing_state.fill_style.to_color_but_fixme_should_accept_any_paint_style());
     did_draw(transformed_rect);
 }
 
@@ -234,7 +241,7 @@ void CanvasRenderingContext2D::stroke_internal(Gfx::Path const& path)
 
     auto& drawing_state = this->drawing_state();
 
-    painter->stroke_path(path, drawing_state.stroke_style, drawing_state.line_width);
+    painter->stroke_path(path, drawing_state.stroke_style.to_color_but_fixme_should_accept_any_paint_style(), drawing_state.line_width);
     did_draw(path.bounding_box());
 }
 
@@ -266,7 +273,7 @@ void CanvasRenderingContext2D::fill_internal(Gfx::Path& path, DeprecatedString c
     else
         dbgln("Unrecognized fillRule for CRC2D.fill() - this problem goes away once we pass an enum instead of a string");
 
-    painter->fill_path(path, drawing_state().fill_style, winding);
+    painter->fill_path(path, *drawing_state().fill_style.to_gfx_paint_style(), winding);
     did_draw(path.bounding_box());
 }