LibWeb: Replace LibGfx gradient painting with new GradientPainting

Userland/Libraries/LibWeb/Painting/BackgroundPainting.cpp

@@ -12,47 +12,11 @@
 #include <LibWeb/Layout/Node.h>
 #include <LibWeb/Painting/BackgroundPainting.h>
 #include <LibWeb/Painting/BorderRadiusCornerClipper.h>
+#include <LibWeb/Painting/GradientPainting.h>
 #include <LibWeb/Painting/PaintContext.h>
 
 namespace Web::Painting {
 
-struct GfxGradient {
-    Gfx::Orientation orientation;
-    Gfx::Color color_a;
-    Gfx::Color color_b;
-};
-
-static Optional<GfxGradient> linear_gradient_to_gfx_gradient(CSS::LinearGradientStyleValue const& linear_gradient, Gfx::FloatRect const& background_rect)
-{
-    if (linear_gradient.color_stop_list().size() != 2)
-        return {};
-
-    auto angle = round_to<int>(linear_gradient.angle_degrees(background_rect));
-    auto color_a = linear_gradient.color_stop_list()[0].color_stop.color;
-    auto color_b = linear_gradient.color_stop_list()[1].color_stop.color;
-    auto orientation = [&]() -> Optional<Gfx::Orientation> {
-        switch (angle) {
-        case 0:
-            swap(color_a, color_b);
-            [[fallthrough]];
-        case 180:
-            return Gfx::Orientation::Vertical;
-        case 270:
-            swap(color_a, color_b);
-            [[fallthrough]];
-        case 90:
-            return Gfx::Orientation::Horizontal;
-        default:
-            return {};
-        }
-    }();
-
-    if (!orientation.has_value())
-        return {};
-
-    return GfxGradient { *orientation, color_a, color_b };
-};
-
 // https://www.w3.org/TR/css-backgrounds-3/#backgrounds
 void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMetrics const& layout_node, Gfx::FloatRect const& border_rect, Color background_color, Vector<CSS::BackgroundLayerData> const* background_layers, BorderRadiiData const& border_radii)
 {
@@ -134,13 +98,10 @@ void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMet
         ScopedCornerRadiusClip corner_clip { painter, clip_rect, clip_box.radii };
 
         if (layer.background_image->is_linear_gradient()) {
-            // FIXME: Paint non-orthogonal gradients, gradients with > 2 color stops, gradients with custom stop positions ...
             // FIXME: Support sizing and positioning rules with gradients.
             auto& linear_gradient = layer.background_image->as_linear_gradient();
-            auto gfx_gradient = linear_gradient_to_gfx_gradient(linear_gradient, border_box.rect);
-            if (gfx_gradient.has_value()) {
-                painter.fill_rect_with_gradient(gfx_gradient->orientation, border_box.rect.to_rounded<int>(), gfx_gradient->color_a, gfx_gradient->color_b);
-            }
+            auto data = resolve_linear_gradient_data(layout_node, border_box.rect, linear_gradient);
+            paint_linear_gradient(context, border_box.rect.to_rounded<int>(), data);
             continue;
         }