LibWeb/Painting: Introduce PaintingCommandExecutor

Decoupling painting command executor from RecordingPainter allows to
introduce painters other than CPU Gfx::Painter :)

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -486,6 +486,7 @@ set(SOURCES
     Painting/PaintContext.cpp
     Painting/Paintable.cpp
     Painting/PaintableBox.cpp
+    Painting/PaintingCommandExecutorCPU.cpp
     Painting/ProgressPaintable.cpp
     Painting/RadioButtonPaintable.cpp
     Painting/RecordingPainter.cpp

Userland/Libraries/LibWeb/Painting/PaintingCommandExecutorCPU.cpp

@@ -0,0 +1,401 @@
+/*
+ * Copyright (c) 2023, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibGfx/Filters/StackBlurFilter.h>
+#include <LibGfx/StylePainter.h>
+#include <LibWeb/Painting/BorderRadiusCornerClipper.h>
+#include <LibWeb/Painting/FilterPainting.h>
+#include <LibWeb/Painting/PaintingCommandExecutorCPU.h>
+#include <LibWeb/Painting/RecordingPainter.h>
+#include <LibWeb/Painting/ShadowPainting.h>
+
+namespace Web::Painting {
+
+PaintingCommandExecutorCPU::PaintingCommandExecutorCPU(Gfx::Bitmap& bitmap)
+    : m_target_bitmap(bitmap)
+{
+    stacking_contexts.append({ Gfx::Painter(bitmap), {}, 1.0f });
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_text_run(Color const& color, Gfx::IntPoint const& baseline_start, String const& string, Gfx::Font const& font)
+{
+    auto& painter = this->painter();
+    painter.draw_text_run(baseline_start, Utf8View(string), font, color);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_text(Gfx::IntRect const& rect, String const& raw_text, Gfx::TextAlignment alignment, Color const& color, Gfx::TextElision elision, Gfx::TextWrapping wrapping, Optional<NonnullRefPtr<Gfx::Font>> const& font)
+{
+    auto& painter = this->painter();
+    if (font.has_value()) {
+        painter.draw_text(rect, raw_text, *font, alignment, color, elision, wrapping);
+    } else {
+        painter.draw_text(rect, raw_text, alignment, color, elision, wrapping);
+    }
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::fill_rect(Gfx::IntRect const& rect, Color const& color)
+{
+    auto& painter = this->painter();
+    painter.fill_rect(rect, color);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_scaled_bitmap(Gfx::IntRect const& dst_rect, Gfx::Bitmap const& bitmap, Gfx::IntRect const& src_rect, float opacity, Gfx::Painter::ScalingMode scaling_mode)
+{
+    auto& painter = this->painter();
+    painter.draw_scaled_bitmap(dst_rect, bitmap, src_rect, opacity, scaling_mode);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::set_clip_rect(Gfx::IntRect const& rect)
+{
+    auto& painter = this->painter();
+    painter.clear_clip_rect();
+    painter.add_clip_rect(rect);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::clear_clip_rect()
+{
+    auto& painter = this->painter();
+    painter.clear_clip_rect();
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::set_font(Gfx::Font const& font)
+{
+    auto& painter = this->painter();
+    painter.set_font(font);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::push_stacking_context(bool semitransparent_or_has_non_identity_transform, float opacity, Gfx::FloatRect const& source_rect, Gfx::FloatRect const& transformed_destination_rect, Gfx::IntPoint const& painter_location)
+{
+    auto& painter = this->painter();
+    if (semitransparent_or_has_non_identity_transform) {
+        auto destination_rect = transformed_destination_rect.to_rounded<int>();
+
+        // FIXME: We should find a way to scale the paintable, rather than paint into a separate bitmap,
+        // then scale it. This snippet now copies the background at the destination, then scales it down/up
+        // to the size of the source (which could add some artefacts, though just scaling the bitmap already does that).
+        // We need to copy the background at the destination because a bunch of our rendering effects now rely on
+        // being able to sample the painter (see border radii, shadows, filters, etc).
+        Gfx::FloatPoint destination_clipped_fixup {};
+        auto try_get_scaled_destination_bitmap = [&]() -> ErrorOr<NonnullRefPtr<Gfx::Bitmap>> {
+            Gfx::IntRect actual_destination_rect;
+            auto bitmap = TRY(painter.get_region_bitmap(destination_rect, Gfx::BitmapFormat::BGRA8888, actual_destination_rect));
+            // get_region_bitmap() may clip to a smaller region if the requested rect goes outside the painter, so we need to account for that.
+            destination_clipped_fixup = Gfx::FloatPoint { destination_rect.location() - actual_destination_rect.location() };
+            destination_rect = actual_destination_rect;
+            if (source_rect.size() != transformed_destination_rect.size()) {
+                auto sx = static_cast<float>(source_rect.width()) / transformed_destination_rect.width();
+                auto sy = static_cast<float>(source_rect.height()) / transformed_destination_rect.height();
+                bitmap = TRY(bitmap->scaled(sx, sy));
+                destination_clipped_fixup.scale_by(sx, sy);
+            }
+            return bitmap;
+        };
+
+        auto bitmap_or_error = try_get_scaled_destination_bitmap();
+        if (bitmap_or_error.is_error()) {
+            // NOTE: If the creation of the bitmap fails, we need to skip all painting commands that belong to this stacking context.
+            //       We don't interrupt the execution of painting commands because get_region_bitmap() returns an error if the requested
+            //       region is outside of the viewport (mmap fails to allocate a zero-size region), which means we can safely proceed
+            //       with execution of commands outside of this stacking context.
+            // FIXME: Change the get_region_bitmap() API to return ErrorOr<Optional<Bitmap>> and exit the execution of commands here
+            //        if we run out of memory.
+            return CommandResult::SkipStackingContext;
+        }
+        auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
+
+        Gfx::Painter stacking_context_painter(bitmap);
+
+        stacking_context_painter.translate(painter_location + destination_clipped_fixup.to_type<int>());
+
+        stacking_contexts.append(StackingContext {
+            .painter = stacking_context_painter,
+            .destination = destination_rect,
+            .opacity = opacity,
+        });
+    } else {
+        painter.save();
+    }
+
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::pop_stacking_context(bool semitransparent_or_has_non_identity_transform, Gfx::Painter::ScalingMode scaling_mode)
+{
+    if (semitransparent_or_has_non_identity_transform) {
+        auto stacking_context = stacking_contexts.take_last();
+        auto bitmap = stacking_context.painter.target();
+        auto destination_rect = stacking_context.destination;
+
+        if (destination_rect.size() == bitmap->size()) {
+            painter().blit(destination_rect.location(), *bitmap, bitmap->rect(), stacking_context.opacity);
+        } else {
+            painter().draw_scaled_bitmap(destination_rect, *bitmap, bitmap->rect(), stacking_context.opacity, scaling_mode);
+        }
+    } else {
+        painter().restore();
+    }
+
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::push_stacking_context_with_mask(Gfx::IntRect const& paint_rect)
+{
+    auto bitmap_or_error = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, paint_rect.size());
+    if (bitmap_or_error.is_error())
+        return CommandResult::Continue;
+    auto bitmap = bitmap_or_error.release_value();
+
+    Gfx::Painter stacking_context_painter(bitmap);
+
+    stacking_context_painter.translate(-paint_rect.location());
+
+    stacking_contexts.append(StackingContext {
+        .painter = stacking_context_painter,
+        .destination = {},
+        .opacity = 1,
+    });
+
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::pop_stacking_context_with_mask(Gfx::IntRect const& paint_rect, RefPtr<Gfx::Bitmap> const& mask_bitmap, Gfx::Bitmap::MaskKind mask_kind, float opacity)
+{
+    auto stacking_context = stacking_contexts.take_last();
+    auto bitmap = stacking_context.painter.target();
+    if (mask_bitmap)
+        bitmap->apply_mask(*mask_bitmap, mask_kind);
+    painter().blit(paint_rect.location(), *bitmap, bitmap->rect(), opacity);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_linear_gradient(Gfx::IntRect const& gradient_rect, Web::Painting::LinearGradientData const& linear_gradient_data)
+{
+    auto const& data = linear_gradient_data;
+    painter().fill_rect_with_linear_gradient(
+        gradient_rect, data.color_stops.list,
+        data.gradient_angle, data.color_stops.repeat_length);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_outer_box_shadow(PaintOuterBoxShadowParams const& outer_box_shadow_params)
+{
+    auto& painter = this->painter();
+    Web::Painting::paint_outer_box_shadow(painter, outer_box_shadow_params);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_inner_box_shadow(PaintOuterBoxShadowParams const& outer_box_shadow_params)
+{
+    auto& painter = this->painter();
+    Web::Painting::paint_inner_box_shadow(painter, outer_box_shadow_params);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_text_shadow(int blur_radius, Gfx::IntRect const& shadow_bounding_rect, Gfx::IntRect const& text_rect, String const& text, Gfx::Font const& font, Color const& color, int fragment_baseline, Gfx::IntPoint const& draw_location)
+{
+    // FIXME: Figure out the maximum bitmap size for all shadows and then allocate it once and reuse it?
+    auto maybe_shadow_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, shadow_bounding_rect.size());
+    if (maybe_shadow_bitmap.is_error()) {
+        dbgln("Unable to allocate temporary bitmap {} for text-shadow rendering: {}", shadow_bounding_rect.size(), maybe_shadow_bitmap.error());
+        return CommandResult::Continue;
+    }
+    auto shadow_bitmap = maybe_shadow_bitmap.release_value();
+
+    Gfx::Painter shadow_painter { *shadow_bitmap };
+    // FIXME: "Spread" the shadow somehow.
+    Gfx::IntPoint baseline_start(text_rect.x(), text_rect.y() + fragment_baseline);
+    shadow_painter.draw_text_run(baseline_start, Utf8View(text), font, color);
+
+    // Blur
+    Gfx::StackBlurFilter filter(*shadow_bitmap);
+    filter.process_rgba(blur_radius, color);
+
+    painter().blit(draw_location, *shadow_bitmap, shadow_bounding_rect);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::fill_rect_with_rounded_corners(Gfx::IntRect const& rect, Color const& color, Gfx::AntiAliasingPainter::CornerRadius const& top_left_radius, Gfx::AntiAliasingPainter::CornerRadius const& top_right_radius, Gfx::AntiAliasingPainter::CornerRadius const& bottom_left_radius, Gfx::AntiAliasingPainter::CornerRadius const& bottom_right_radius, Optional<Gfx::FloatPoint> const& aa_translation)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    if (aa_translation.has_value())
+        aa_painter.translate(*aa_translation);
+    aa_painter.fill_rect_with_rounded_corners(
+        rect,
+        color,
+        top_left_radius,
+        top_right_radius,
+        bottom_right_radius,
+        bottom_left_radius);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::fill_path_using_color(Gfx::Path const& path, Color const& color, Gfx::Painter::WindingRule winding_rule, Optional<Gfx::FloatPoint> const& aa_translation)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    if (aa_translation.has_value())
+        aa_painter.translate(*aa_translation);
+    aa_painter.fill_path(path, color, winding_rule);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::fill_path_using_paint_style(Gfx::Path const& path, Gfx::PaintStyle const& paint_style, Gfx::Painter::WindingRule winding_rule, float opacity, Optional<Gfx::FloatPoint> const& aa_translation)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    if (aa_translation.has_value())
+        aa_painter.translate(*aa_translation);
+    aa_painter.fill_path(path, paint_style, opacity, winding_rule);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::stroke_path_using_color(Gfx::Path const& path, Color const& color, float thickness, Optional<Gfx::FloatPoint> const& aa_translation)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    if (aa_translation.has_value())
+        aa_painter.translate(*aa_translation);
+    aa_painter.stroke_path(path, color, thickness);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::stroke_path_using_paint_style(Gfx::Path const& path, Gfx::PaintStyle const& paint_style, float thickness, float opacity, Optional<Gfx::FloatPoint> const& aa_translation)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    if (aa_translation.has_value())
+        aa_painter.translate(*aa_translation);
+    aa_painter.stroke_path(path, paint_style, thickness, opacity);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_ellipse(Gfx::IntRect const& rect, Color const& color, int thickness)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    aa_painter.draw_ellipse(rect, color, thickness);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::fill_ellipse(Gfx::IntRect const& rect, Color const& color, Gfx::AntiAliasingPainter::BlendMode blend_mode)
+{
+    Gfx::AntiAliasingPainter aa_painter(painter());
+    aa_painter.fill_ellipse(rect, color, blend_mode);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_line(Color const& color, Gfx::IntPoint const& from, Gfx::IntPoint const& to, int thickness, Gfx::Painter::LineStyle style, Color const& alternate_color)
+{
+    if (style == Gfx::Painter::LineStyle::Dotted) {
+        Gfx::AntiAliasingPainter aa_painter(painter());
+        aa_painter.draw_line(from, to, color, thickness, style, alternate_color);
+    } else {
+        painter().draw_line(from, to, color, thickness, style, alternate_color);
+    }
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_signed_distance_field(Gfx::IntRect const& rect, Color const& color, Gfx::GrayscaleBitmap const& sdf, float smoothing)
+{
+    painter().draw_signed_distance_field(rect, color, sdf, smoothing);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_progressbar(Gfx::IntRect const& frame_rect, Gfx::IntRect const& progress_rect, Palette const& palette, int min, int max, int value, StringView const& text)
+{
+    auto& painter = this->painter();
+    Gfx::StylePainter::paint_progressbar(painter, progress_rect, palette, min, max, value, text);
+    Gfx::StylePainter::paint_frame(painter, frame_rect, palette, Gfx::FrameStyle::RaisedBox);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_frame(Gfx::IntRect const& rect, Palette const& palette, Gfx::FrameStyle style)
+{
+    Gfx::StylePainter::paint_frame(painter(), rect, palette, style);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::apply_backdrop_filter(Gfx::IntRect const& backdrop_region, Web::CSS::ResolvedBackdropFilter const& backdrop_filter)
+{
+    auto& painter = this->painter();
+
+    // This performs the backdrop filter operation: https://drafts.fxtf.org/filter-effects-2/#backdrop-filter-operation
+
+    // Note: The region bitmap can be smaller than the backdrop_region if it's at the edge of canvas.
+    // Note: This is in DevicePixels, but we use an IntRect because `get_region_bitmap()` below writes to it.
+
+    // FIXME: Go through the steps to find the "Backdrop Root Image"
+    // https://drafts.fxtf.org/filter-effects-2/#BackdropRoot
+
+    // 1. Copy the Backdrop Root Image into a temporary buffer, such as a raster image. Call this buffer T’.
+    Gfx::IntRect actual_region {};
+    auto maybe_backdrop_bitmap = painter.get_region_bitmap(backdrop_region, Gfx::BitmapFormat::BGRA8888, actual_region);
+    if (actual_region.is_empty())
+        return CommandResult::Continue;
+    if (maybe_backdrop_bitmap.is_error()) {
+        dbgln("Failed get region bitmap for backdrop-filter");
+        return CommandResult::Continue;
+    }
+    auto backdrop_bitmap = maybe_backdrop_bitmap.release_value();
+
+    // 2. Apply the backdrop-filter’s filter operations to the entire contents of T'.
+    apply_filter_list(*backdrop_bitmap, backdrop_filter.filters);
+
+    // FIXME: 3. If element B has any transforms (between B and the Backdrop Root), apply the inverse of those transforms to the contents of T’.
+
+    // 4. Apply a clip to the contents of T’, using the border box of element B, including border-radius if specified. Note that the children of B are not considered for the sizing or location of this clip.
+    // FIXME: 5. Draw all of element B, including its background, border, and any children elements, into T’.
+    // FXIME: 6. If element B has any transforms, effects, or clips, apply those to T’.
+
+    // 7. Composite the contents of T’ into element B’s parent, using source-over compositing.
+    painter.blit(actual_region.location(), *backdrop_bitmap, backdrop_bitmap->rect());
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_rect(Gfx::IntRect const& rect, Color const& color, bool rough)
+{
+    painter().draw_rect(rect, color, rough);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_radial_gradient(Gfx::IntRect const& rect, Web::Painting::RadialGradientData const& radial_gradient_data, Gfx::IntPoint const& center, Gfx::IntSize const& size)
+{
+    painter().fill_rect_with_radial_gradient(rect, radial_gradient_data.color_stops.list, center, size, radial_gradient_data.color_stops.repeat_length);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::paint_conic_gradient(Gfx::IntRect const& rect, Web::Painting::ConicGradientData const& conic_gradient_data, Gfx::IntPoint const& position)
+{
+    painter().fill_rect_with_conic_gradient(rect, conic_gradient_data.color_stops.list, position, conic_gradient_data.start_angle, conic_gradient_data.color_stops.repeat_length);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::draw_triangle_wave(Gfx::IntPoint const& p1, Gfx::IntPoint const& p2, Color const& color, int amplitude, int thickness)
+{
+    painter().draw_triangle_wave(p1, p2, color, amplitude, thickness);
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::sample_under_corners(BorderRadiusCornerClipper& corner_clipper)
+{
+    corner_clipper.sample_under_corners(painter());
+    return CommandResult::Continue;
+}
+
+CommandResult PaintingCommandExecutorCPU::blit_corner_clipping(BorderRadiusCornerClipper& corner_clipper)
+{
+    corner_clipper.blit_corner_clipping(painter());
+    return CommandResult::Continue;
+}
+
+bool PaintingCommandExecutorCPU::would_be_fully_clipped_by_painter(Gfx::IntRect rect) const
+{
+    return !painter().clip_rect().intersects(rect.translated(painter().translation()));
+}
+
+}

Userland/Libraries/LibWeb/Painting/PaintingCommandExecutorCPU.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2023, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Painting/RecordingPainter.h>
+
+namespace Web::Painting {
+
+class PaintingCommandExecutorCPU : public PaintingCommandExecutor {
+public:
+    CommandResult draw_text_run(Color const&, Gfx::IntPoint const& baseline_start, String const& string, Gfx::Font const& font) override;
+    CommandResult draw_text(Gfx::IntRect const& rect, String const& raw_text, Gfx::TextAlignment alignment, Color const&, Gfx::TextElision, Gfx::TextWrapping, Optional<NonnullRefPtr<Gfx::Font>> const&) override;
+    CommandResult fill_rect(Gfx::IntRect const& rect, Color const&) override;
+    CommandResult draw_scaled_bitmap(Gfx::IntRect const& dst_rect, Gfx::Bitmap const& bitmap, Gfx::IntRect const& src_rect, float opacity, Gfx::Painter::ScalingMode scaling_mode) override;
+    CommandResult set_clip_rect(Gfx::IntRect const& rect) override;
+    CommandResult clear_clip_rect() override;
+    CommandResult set_font(Gfx::Font const&) override;
+    CommandResult push_stacking_context(bool semitransparent_or_has_non_identity_transform, float opacity, Gfx::FloatRect const& source_rect, Gfx::FloatRect const& transformed_destination_rect, Gfx::IntPoint const& painter_location) override;
+    CommandResult pop_stacking_context(bool semitransparent_or_has_non_identity_transform, Gfx::Painter::ScalingMode scaling_mode) override;
+    CommandResult push_stacking_context_with_mask(Gfx::IntRect const&) override;
+    CommandResult pop_stacking_context_with_mask(Gfx::IntRect const&, RefPtr<Gfx::Bitmap> const& mask_bitmap, Gfx::Bitmap::MaskKind mask_kind, float opacity) override;
+    CommandResult paint_linear_gradient(Gfx::IntRect const&, Web::Painting::LinearGradientData const&) override;
+    CommandResult paint_outer_box_shadow(PaintOuterBoxShadowParams const&) override;
+    CommandResult paint_inner_box_shadow(PaintOuterBoxShadowParams const&) override;
+    CommandResult paint_text_shadow(int blur_radius, Gfx::IntRect const& shadow_bounding_rect, Gfx::IntRect const& text_rect, String const& text, Gfx::Font const&, Color const&, int fragment_baseline, Gfx::IntPoint const& draw_location) override;
+    CommandResult fill_rect_with_rounded_corners(Gfx::IntRect const&, Color const&, Gfx::AntiAliasingPainter::CornerRadius const& top_left_radius, Gfx::AntiAliasingPainter::CornerRadius const& top_right_radius, Gfx::AntiAliasingPainter::CornerRadius const& bottom_left_radius, Gfx::AntiAliasingPainter::CornerRadius const& bottom_right_radius, Optional<Gfx::FloatPoint> const& aa_translation) override;
+    CommandResult fill_path_using_color(Gfx::Path const&, Color const&, Gfx::Painter::WindingRule winding_rule, Optional<Gfx::FloatPoint> const& aa_translation) override;
+    CommandResult fill_path_using_paint_style(Gfx::Path const&, Gfx::PaintStyle const& paint_style, Gfx::Painter::WindingRule winding_rule, float opacity, Optional<Gfx::FloatPoint> const& aa_translation) override;
+    CommandResult stroke_path_using_color(Gfx::Path const&, Color const& color, float thickness, Optional<Gfx::FloatPoint> const& aa_translation) override;
+    CommandResult stroke_path_using_paint_style(Gfx::Path const& path, Gfx::PaintStyle const& paint_style, float thickness, float opacity, Optional<Gfx::FloatPoint> const& aa_translation) override;
+    CommandResult draw_ellipse(Gfx::IntRect const& rect, Color const& color, int thickness) override;
+    CommandResult fill_ellipse(Gfx::IntRect const& rect, Color const& color, Gfx::AntiAliasingPainter::BlendMode blend_mode) override;
+    CommandResult draw_line(Color const&, Gfx::IntPoint const& from, Gfx::IntPoint const& to, int thickness, Gfx::Painter::LineStyle style, Color const& alternate_color) override;
+    CommandResult draw_signed_distance_field(Gfx::IntRect const& rect, Color const&, Gfx::GrayscaleBitmap const& sdf, float smoothing) override;
+    CommandResult paint_progressbar(Gfx::IntRect const& frame_rect, Gfx::IntRect const& progress_rect, Palette const& palette, int min, int max, int value, StringView const& text) override;
+    CommandResult paint_frame(Gfx::IntRect const& rect, Palette const&, Gfx::FrameStyle) override;
+    CommandResult apply_backdrop_filter(Gfx::IntRect const& backdrop_region, Web::CSS::ResolvedBackdropFilter const& backdrop_filter) override;
+    CommandResult draw_rect(Gfx::IntRect const& rect, Color const&, bool rough) override;
+    CommandResult paint_radial_gradient(Gfx::IntRect const& rect, Web::Painting::RadialGradientData const& radial_gradient_data, Gfx::IntPoint const& center, Gfx::IntSize const& size) override;
+    CommandResult paint_conic_gradient(Gfx::IntRect const& rect, Web::Painting::ConicGradientData const& conic_gradient_data, Gfx::IntPoint const& position) override;
+    CommandResult draw_triangle_wave(Gfx::IntPoint const& p1, Gfx::IntPoint const& p2, Color const&, int amplitude, int thickness) override;
+    CommandResult sample_under_corners(BorderRadiusCornerClipper&) override;
+    CommandResult blit_corner_clipping(BorderRadiusCornerClipper&) override;
+
+    bool would_be_fully_clipped_by_painter(Gfx::IntRect) const override;
+
+    PaintingCommandExecutorCPU(Gfx::Bitmap& bitmap);
+
+private:
+    Gfx::Bitmap& m_target_bitmap;
+
+    struct StackingContext {
+        Gfx::Painter painter;
+        Gfx::IntRect destination;
+        float opacity;
+    };
+
+    [[nodiscard]] Gfx::Painter const& painter() const { return stacking_contexts.last().painter; }
+    [[nodiscard]] Gfx::Painter& painter() { return stacking_contexts.last().painter; }
+
+    Vector<StackingContext> stacking_contexts;
+};
+
+}

Userland/Libraries/LibWeb/Painting/RecordingPainter.cpp

@@ -4,441 +4,26 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <LibGfx/Filters/StackBlurFilter.h>
-#include <LibGfx/StylePainter.h>
-#include <LibWeb/Painting/BorderRadiusCornerClipper.h>
-#include <LibWeb/Painting/FilterPainting.h>
 #include <LibWeb/Painting/RecordingPainter.h>
 #include <LibWeb/Painting/ShadowPainting.h>
 
 namespace Web::Painting {
 
-struct CommandExecutionState {
-    struct StackingContext {
-        Gfx::Painter painter;
-        Gfx::IntRect destination;
-        float opacity;
-    };
-
-    [[nodiscard]] Gfx::Painter const& painter() const { return stacking_contexts.last().painter; }
-    [[nodiscard]] Gfx::Painter& painter() { return stacking_contexts.last().painter; }
-
-    [[nodiscard]] bool would_be_fully_clipped_by_painter(Gfx::IntRect rect) const
-    {
-        return !painter().clip_rect().intersects(rect.translated(painter().translation()));
-    }
-
-    Vector<StackingContext> stacking_contexts;
-};
-
-CommandResult FillRectWithRoundedCorners::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    if (aa_translation.has_value())
-        aa_painter.translate(*aa_translation);
-    aa_painter.fill_rect_with_rounded_corners(
-        rect,
-        color,
-        top_left_radius,
-        top_right_radius,
-        bottom_right_radius,
-        bottom_left_radius);
-    return CommandResult::Continue;
-}
-
-CommandResult DrawText::execute(CommandExecutionState& state) const
-{
-    if (state.would_be_fully_clipped_by_painter(rect))
-        return CommandResult::Continue;
-    auto& painter = state.painter();
-    if (font.has_value()) {
-        painter.draw_text(rect, raw_text, *font, alignment, color, elision, wrapping);
-    } else {
-        painter.draw_text(rect, raw_text, alignment, color, elision, wrapping);
-    }
-    return CommandResult::Continue;
-}
-
-CommandResult DrawTextRun::execute(CommandExecutionState& state) const
-{
-    if (state.would_be_fully_clipped_by_painter(rect))
-        return CommandResult::Continue;
-    auto& painter = state.painter();
-    painter.draw_text_run(baseline_start, Utf8View(string), font, color);
-    return CommandResult::Continue;
-}
-
-CommandResult FillPathUsingColor::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    if (aa_translation.has_value())
-        aa_painter.translate(*aa_translation);
-    aa_painter.fill_path(path, color, winding_rule);
-    return CommandResult::Continue;
-}
-
-CommandResult FillPathUsingPaintStyle::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    if (aa_translation.has_value())
-        aa_painter.translate(*aa_translation);
-    aa_painter.fill_path(path, paint_style, opacity, winding_rule);
-    return CommandResult::Continue;
-}
-
-CommandResult StrokePathUsingColor::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    if (aa_translation.has_value())
-        aa_painter.translate(*aa_translation);
-    aa_painter.stroke_path(path, color, thickness);
-    return CommandResult::Continue;
-}
-
-CommandResult StrokePathUsingPaintStyle::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    if (aa_translation.has_value())
-        aa_painter.translate(*aa_translation);
-    aa_painter.stroke_path(path, paint_style, thickness, opacity);
-    return CommandResult::Continue;
-}
-
-CommandResult FillRect::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.fill_rect(rect, color);
-    return CommandResult::Continue;
-}
-
-CommandResult DrawScaledBitmap::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.draw_scaled_bitmap(dst_rect, bitmap, src_rect, opacity, scaling_mode);
-    return CommandResult::Continue;
-}
-
-CommandResult SetClipRect::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.clear_clip_rect();
-    painter.add_clip_rect(rect);
-    return CommandResult::Continue;
-}
-
-CommandResult ClearClipRect::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.clear_clip_rect();
-    return CommandResult::Continue;
-}
-
-CommandResult SetFont::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.set_font(font);
-    return CommandResult::Continue;
-}
-
-CommandResult PushStackingContext::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    if (semitransparent_or_has_non_identity_transform) {
-        auto destination_rect = transformed_destination_rect.to_rounded<int>();
-
-        // FIXME: We should find a way to scale the paintable, rather than paint into a separate bitmap,
-        // then scale it. This snippet now copies the background at the destination, then scales it down/up
-        // to the size of the source (which could add some artefacts, though just scaling the bitmap already does that).
-        // We need to copy the background at the destination because a bunch of our rendering effects now rely on
-        // being able to sample the painter (see border radii, shadows, filters, etc).
-        Gfx::FloatPoint destination_clipped_fixup {};
-        auto try_get_scaled_destination_bitmap = [&]() -> ErrorOr<NonnullRefPtr<Gfx::Bitmap>> {
-            Gfx::IntRect actual_destination_rect;
-            auto bitmap = TRY(painter.get_region_bitmap(destination_rect, Gfx::BitmapFormat::BGRA8888, actual_destination_rect));
-            // get_region_bitmap() may clip to a smaller region if the requested rect goes outside the painter, so we need to account for that.
-            destination_clipped_fixup = Gfx::FloatPoint { destination_rect.location() - actual_destination_rect.location() };
-            destination_rect = actual_destination_rect;
-            if (source_rect.size() != transformed_destination_rect.size()) {
-                auto sx = static_cast<float>(source_rect.width()) / transformed_destination_rect.width();
-                auto sy = static_cast<float>(source_rect.height()) / transformed_destination_rect.height();
-                bitmap = TRY(bitmap->scaled(sx, sy));
-                destination_clipped_fixup.scale_by(sx, sy);
-            }
-            return bitmap;
-        };
-
-        auto bitmap_or_error = try_get_scaled_destination_bitmap();
-        if (bitmap_or_error.is_error()) {
-            // NOTE: If the creation of the bitmap fails, we need to skip all painting commands that belong to this stacking context.
-            //       We don't interrupt the execution of painting commands because get_region_bitmap() returns an error if the requested
-            //       region is outside of the viewport (mmap fails to allocate a zero-size region), which means we can safely proceed
-            //       with execution of commands outside of this stacking context.
-            // FIXME: Change the get_region_bitmap() API to return ErrorOr<Optional<Bitmap>> and exit the execution of commands here
-            //        if we run out of memory.
-            return CommandResult::SkipStackingContext;
-        }
-        auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
-
-        Gfx::Painter stacking_context_painter(bitmap);
-
-        stacking_context_painter.translate(painter_location + destination_clipped_fixup.to_type<int>());
-
-        state.stacking_contexts.append(CommandExecutionState::StackingContext {
-            .painter = stacking_context_painter,
-            .destination = destination_rect,
-            .opacity = opacity,
-        });
-    } else {
-        state.painter().save();
-    }
-
-    return CommandResult::Continue;
-}
-
-CommandResult PopStackingContext::execute(CommandExecutionState& state) const
-{
-    if (semitransparent_or_has_non_identity_transform) {
-        auto stacking_context = state.stacking_contexts.take_last();
-        auto bitmap = stacking_context.painter.target();
-        auto destination_rect = stacking_context.destination;
-
-        if (destination_rect.size() == bitmap->size()) {
-            state.painter().blit(destination_rect.location(), *bitmap, bitmap->rect(), stacking_context.opacity);
-        } else {
-            state.painter().draw_scaled_bitmap(destination_rect, *bitmap, bitmap->rect(), stacking_context.opacity, scaling_mode);
-        }
-    } else {
-        state.painter().restore();
-    }
-
-    return CommandResult::Continue;
-}
-
-CommandResult PushStackingContextWithMask::execute(CommandExecutionState& state) const
-{
-    auto bitmap_or_error = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, paint_rect.size());
-    if (bitmap_or_error.is_error())
-        return CommandResult::Continue;
-    auto bitmap = bitmap_or_error.release_value();
-
-    Gfx::Painter stacking_context_painter(bitmap);
-
-    stacking_context_painter.translate(-paint_rect.location());
-
-    state.stacking_contexts.append(CommandExecutionState::StackingContext {
-        .painter = stacking_context_painter,
-        .destination = {},
-        .opacity = 1,
-    });
-
-    return CommandResult::Continue;
-}
-
-CommandResult PopStackingContextWithMask::execute(CommandExecutionState& state) const
-{
-    auto stacking_context = state.stacking_contexts.take_last();
-    auto bitmap = stacking_context.painter.target();
-    if (mask_bitmap)
-        bitmap->apply_mask(*mask_bitmap, mask_kind);
-    state.painter().blit(paint_rect.location(), *bitmap, bitmap->rect(), opacity);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintLinearGradient::execute(CommandExecutionState& state) const
-{
-    auto const& data = linear_gradient_data;
-    state.painter().fill_rect_with_linear_gradient(
-        gradient_rect, data.color_stops.list,
-        data.gradient_angle, data.color_stops.repeat_length);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintRadialGradient::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.fill_rect_with_radial_gradient(rect, radial_gradient_data.color_stops.list, center, size, radial_gradient_data.color_stops.repeat_length);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintConicGradient::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.fill_rect_with_conic_gradient(rect, conic_gradient_data.color_stops.list, position, conic_gradient_data.start_angle, conic_gradient_data.color_stops.repeat_length);
-    return CommandResult::Continue;
-}
-
 Gfx::IntRect PaintOuterBoxShadow::bounding_rect() const
 {
     return get_outer_box_shadow_bounding_rect(outer_box_shadow_params);
 }
 
-CommandResult PaintOuterBoxShadow::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    paint_outer_box_shadow(painter, outer_box_shadow_params);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintInnerBoxShadow::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    paint_inner_box_shadow(painter, outer_box_shadow_params);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintTextShadow::execute(CommandExecutionState& state) const
-{
-    // FIXME: Figure out the maximum bitmap size for all shadows and then allocate it once and reuse it?
-    auto maybe_shadow_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, shadow_bounding_rect.size());
-    if (maybe_shadow_bitmap.is_error()) {
-        dbgln("Unable to allocate temporary bitmap {} for text-shadow rendering: {}", shadow_bounding_rect.size(), maybe_shadow_bitmap.error());
-        return CommandResult::Continue;
-    }
-    auto shadow_bitmap = maybe_shadow_bitmap.release_value();
-
-    Gfx::Painter shadow_painter { *shadow_bitmap };
-    // FIXME: "Spread" the shadow somehow.
-    Gfx::IntPoint baseline_start(text_rect.x(), text_rect.y() + fragment_baseline);
-    shadow_painter.draw_text_run(baseline_start, Utf8View(text), font, color);
-
-    // Blur
-    Gfx::StackBlurFilter filter(*shadow_bitmap);
-    filter.process_rgba(blur_radius, color);
-
-    auto& painter = state.painter();
-    painter.blit(draw_location, *shadow_bitmap, shadow_bounding_rect);
-    return CommandResult::Continue;
-}
-
-CommandResult DrawEllipse::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    aa_painter.draw_ellipse(rect, color, thickness);
-    return CommandResult::Continue;
-}
-
-CommandResult FillElipse::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::AntiAliasingPainter aa_painter(painter);
-    aa_painter.fill_ellipse(rect, color, blend_mode);
-    return CommandResult::Continue;
-}
-
-CommandResult DrawLine::execute(CommandExecutionState& state) const
-{
-    if (style == Gfx::Painter::LineStyle::Dotted) {
-        Gfx::AntiAliasingPainter aa_painter(state.painter());
-        aa_painter.draw_line(from, to, color, thickness, style, alternate_color);
-    } else {
-        state.painter().draw_line(from, to, color, thickness, style, alternate_color);
-    }
-    return CommandResult::Continue;
-}
-
-CommandResult DrawSignedDistanceField::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.draw_signed_distance_field(rect, color, sdf, smoothing);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintProgressbar::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::StylePainter::paint_progressbar(painter, progress_rect, palette, min, max, value, text);
-    Gfx::StylePainter::paint_frame(painter, frame_rect, palette, Gfx::FrameStyle::RaisedBox);
-    return CommandResult::Continue;
-}
-
-CommandResult PaintFrame::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    Gfx::StylePainter::paint_frame(painter, rect, palette, style);
-    return CommandResult::Continue;
-}
-
-CommandResult ApplyBackdropFilter::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-
-    // This performs the backdrop filter operation: https://drafts.fxtf.org/filter-effects-2/#backdrop-filter-operation
-
-    // Note: The region bitmap can be smaller than the backdrop_region if it's at the edge of canvas.
-    // Note: This is in DevicePixels, but we use an IntRect because `get_region_bitmap()` below writes to it.
-
-    // FIXME: Go through the steps to find the "Backdrop Root Image"
-    // https://drafts.fxtf.org/filter-effects-2/#BackdropRoot
-
-    // 1. Copy the Backdrop Root Image into a temporary buffer, such as a raster image. Call this buffer T’.
-    Gfx::IntRect actual_region {};
-    auto maybe_backdrop_bitmap = painter.get_region_bitmap(backdrop_region, Gfx::BitmapFormat::BGRA8888, actual_region);
-    if (actual_region.is_empty())
-        return CommandResult::Continue;
-    if (maybe_backdrop_bitmap.is_error()) {
-        dbgln("Failed get region bitmap for backdrop-filter");
-        return CommandResult::Continue;
-    }
-    auto backdrop_bitmap = maybe_backdrop_bitmap.release_value();
-
-    // 2. Apply the backdrop-filter’s filter operations to the entire contents of T'.
-    apply_filter_list(*backdrop_bitmap, backdrop_filter.filters);
-
-    // FIXME: 3. If element B has any transforms (between B and the Backdrop Root), apply the inverse of those transforms to the contents of T’.
-
-    // 4. Apply a clip to the contents of T’, using the border box of element B, including border-radius if specified. Note that the children of B are not considered for the sizing or location of this clip.
-    // FIXME: 5. Draw all of element B, including its background, border, and any children elements, into T’.
-    // FXIME: 6. If element B has any transforms, effects, or clips, apply those to T’.
-
-    // 7. Composite the contents of T’ into element B’s parent, using source-over compositing.
-    painter.blit(actual_region.location(), *backdrop_bitmap, backdrop_bitmap->rect());
-    return CommandResult::Continue;
-}
-
-CommandResult DrawRect::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.draw_rect(rect, color, rough);
-    return CommandResult::Continue;
-}
-
-CommandResult DrawTriangleWave::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    painter.draw_triangle_wave(p1, p2, color, amplitude, thickness);
-    return CommandResult::Continue;
-}
-
 Gfx::IntRect SampleUnderCorners::bounding_rect() const
 {
     return corner_clipper->border_rect().to_type<int>();
 }
 
-CommandResult SampleUnderCorners::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    corner_clipper->sample_under_corners(painter);
-    return CommandResult::Continue;
-}
-
 Gfx::IntRect BlitCornerClipping::bounding_rect() const
 {
     return corner_clipper->border_rect().to_type<int>();
 }
 
-CommandResult BlitCornerClipping::execute(CommandExecutionState& state) const
-{
-    auto& painter = state.painter();
-    corner_clipper->blit_corner_clipping(painter);
-    return CommandResult::Continue;
-}
-
 void RecordingPainter::sample_under_corners(NonnullRefPtr<BorderRadiusCornerClipper> corner_clipper)
 {
     push_command(SampleUnderCorners { corner_clipper });
@@ -825,22 +410,117 @@ static Optional<Gfx::IntRect> command_bounding_rectangle(PaintingCommand const&
         });
 }
 
-void RecordingPainter::execute(Gfx::Bitmap& bitmap)
+void RecordingPainter::execute(PaintingCommandExecutor& executor)
 {
-    CommandExecutionState state;
-    state.stacking_contexts.append(CommandExecutionState::StackingContext {
-        .painter = Gfx::Painter(bitmap),
-        .destination = Gfx::IntRect { 0, 0, 0, 0 },
-        .opacity = 1,
-    });
-
     size_t next_command_index = 0;
     while (next_command_index < m_painting_commands.size()) {
         auto& command = m_painting_commands[next_command_index++];
         auto bounding_rect = command_bounding_rectangle(command);
-        if (bounding_rect.has_value() && state.would_be_fully_clipped_by_painter(*bounding_rect))
+        if (bounding_rect.has_value() && executor.would_be_fully_clipped_by_painter(*bounding_rect)) {
             continue;
-        auto result = command.visit([&](auto const& command) { return command.execute(state); });
+        }
+
+        auto result = command.visit(
+            [&](DrawTextRun const& command) {
+                return executor.draw_text_run(command.color, command.baseline_start, command.string, command.font);
+            },
+            [&](DrawText const& command) {
+                return executor.draw_text(command.rect, command.raw_text, command.alignment, command.color, command.elision, command.wrapping, command.font);
+            },
+            [&](FillRect const& command) {
+                return executor.fill_rect(command.rect, command.color);
+            },
+            [&](DrawScaledBitmap const& command) {
+                return executor.draw_scaled_bitmap(command.dst_rect, command.bitmap, command.src_rect, command.opacity, command.scaling_mode);
+            },
+            [&](SetClipRect const& command) {
+                return executor.set_clip_rect(command.rect);
+            },
+            [&](ClearClipRect const&) {
+                return executor.clear_clip_rect();
+            },
+            [&](SetFont const& command) {
+                return executor.set_font(command.font);
+            },
+            [&](PushStackingContext const& command) {
+                return executor.push_stacking_context(command.semitransparent_or_has_non_identity_transform, command.opacity, command.source_rect, command.transformed_destination_rect, command.painter_location);
+            },
+            [&](PopStackingContext const& command) {
+                return executor.pop_stacking_context(command.semitransparent_or_has_non_identity_transform, command.scaling_mode);
+            },
+            [&](PushStackingContextWithMask const& command) {
+                return executor.push_stacking_context_with_mask(command.paint_rect);
+            },
+            [&](PopStackingContextWithMask const& command) {
+                return executor.pop_stacking_context_with_mask(command.paint_rect, command.mask_bitmap, command.mask_kind, command.opacity);
+            },
+            [&](PaintLinearGradient const& command) {
+                return executor.paint_linear_gradient(command.gradient_rect, command.linear_gradient_data);
+            },
+            [&](PaintRadialGradient const& command) {
+                return executor.paint_radial_gradient(command.rect, command.radial_gradient_data, command.center, command.size);
+            },
+            [&](PaintConicGradient const& command) {
+                return executor.paint_conic_gradient(command.rect, command.conic_gradient_data, command.position);
+            },
+            [&](PaintOuterBoxShadow const& command) {
+                return executor.paint_outer_box_shadow(command.outer_box_shadow_params);
+            },
+            [&](PaintInnerBoxShadow const& command) {
+                return executor.paint_inner_box_shadow(command.outer_box_shadow_params);
+            },
+            [&](PaintTextShadow const& command) {
+                return executor.paint_text_shadow(command.blur_radius, command.shadow_bounding_rect, command.text_rect, command.text, command.font, command.color, command.fragment_baseline, command.draw_location);
+            },
+            [&](FillRectWithRoundedCorners const& command) {
+                return executor.fill_rect_with_rounded_corners(command.rect, command.color, command.top_left_radius, command.top_right_radius, command.bottom_left_radius, command.bottom_right_radius, command.aa_translation);
+            },
+            [&](FillPathUsingColor const& command) {
+                return executor.fill_path_using_color(command.path, command.color, command.winding_rule, command.aa_translation);
+            },
+            [&](FillPathUsingPaintStyle const& command) {
+                return executor.fill_path_using_paint_style(command.path, command.paint_style, command.winding_rule, command.opacity, command.aa_translation);
+            },
+            [&](StrokePathUsingColor const& command) {
+                return executor.stroke_path_using_color(command.path, command.color, command.thickness, command.aa_translation);
+            },
+            [&](StrokePathUsingPaintStyle const& command) {
+                return executor.stroke_path_using_paint_style(command.path, command.paint_style, command.thickness, command.opacity, command.aa_translation);
+            },
+            [&](DrawEllipse const& command) {
+                return executor.draw_ellipse(command.rect, command.color, command.thickness);
+            },
+            [&](FillElipse const& command) {
+                return executor.fill_ellipse(command.rect, command.color, command.blend_mode);
+            },
+            [&](DrawLine const& command) {
+                return executor.draw_line(command.color, command.from, command.to, command.thickness, command.style, command.alternate_color);
+            },
+            [&](DrawSignedDistanceField const& command) {
+                return executor.draw_signed_distance_field(command.rect, command.color, command.sdf, command.smoothing);
+            },
+            [&](PaintProgressbar const& command) {
+                return executor.paint_progressbar(command.frame_rect, command.progress_rect, command.palette, command.min, command.max, command.value, command.text);
+            },
+            [&](PaintFrame const& command) {
+                return executor.paint_frame(command.rect, command.palette, command.style);
+            },
+            [&](ApplyBackdropFilter const& command) {
+                return executor.apply_backdrop_filter(command.backdrop_region, command.backdrop_filter);
+            },
+            [&](DrawRect const& command) {
+                return executor.draw_rect(command.rect, command.color, command.rough);
+            },
+            [&](DrawTriangleWave const& command) {
+                return executor.draw_triangle_wave(command.p1, command.p2, command.color, command.amplitude, command.thickness);
+            },
+            [&](SampleUnderCorners const& command) {
+                return executor.sample_under_corners(command.corner_clipper);
+            },
+            [&](BlitCornerClipping const& command) {
+                return executor.blit_corner_clipping(command.corner_clipper);
+            });
+
         if (result == CommandResult::SkipStackingContext) {
             auto stacking_context_nesting_level = 1;
             while (next_command_index < m_painting_commands.size()) {
@@ -857,8 +537,6 @@ void RecordingPainter::execute(Gfx::Bitmap& bitmap)
             }
         }
     }
-
-    VERIFY(state.stacking_contexts.size() == 1);
 }
 
 }

Userland/Libraries/LibWeb/Painting/RecordingPainter.h

@@ -33,8 +33,6 @@
 
 namespace Web::Painting {
 
-struct CommandExecutionState;
-
 enum class CommandResult {
     Continue,
     SkipStackingContext,
@@ -48,7 +46,6 @@ struct DrawTextRun {
     Gfx::IntRect rect;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawText {
@@ -61,7 +58,6 @@ struct DrawText {
     Optional<NonnullRefPtr<Gfx::Font>> font {};
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct FillRect {
@@ -69,7 +65,6 @@ struct FillRect {
     Color color;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawScaledBitmap {
@@ -80,23 +75,16 @@ struct DrawScaledBitmap {
     Gfx::Painter::ScalingMode scaling_mode;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return dst_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct SetClipRect {
     Gfx::IntRect rect;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
-struct ClearClipRect {
+struct ClearClipRect { };
-    CommandResult execute(CommandExecutionState&) const;
-};
 
 struct SetFont {
     NonnullRefPtr<Gfx::Font> font;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PushStackingContext {
@@ -106,21 +94,15 @@ struct PushStackingContext {
     Gfx::FloatRect source_rect;
     Gfx::FloatRect transformed_destination_rect;
     Gfx::IntPoint painter_location;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PopStackingContext {
     bool semitransparent_or_has_non_identity_transform;
     Gfx::Painter::ScalingMode scaling_mode;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PushStackingContextWithMask {
     Gfx::IntRect paint_rect;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PopStackingContextWithMask {
@@ -128,8 +110,6 @@ struct PopStackingContextWithMask {
     RefPtr<Gfx::Bitmap> mask_bitmap;
     Gfx::Bitmap::MaskKind mask_kind;
     float opacity;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintLinearGradient {
@@ -137,20 +117,16 @@ struct PaintLinearGradient {
     LinearGradientData linear_gradient_data;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return gradient_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintOuterBoxShadow {
     PaintOuterBoxShadowParams outer_box_shadow_params;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const;
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintInnerBoxShadow {
     PaintOuterBoxShadowParams outer_box_shadow_params;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintTextShadow {
@@ -164,7 +140,6 @@ struct PaintTextShadow {
     Gfx::IntPoint draw_location;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return { draw_location, shadow_bounding_rect.size() }; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct FillRectWithRoundedCorners {
@@ -177,7 +152,6 @@ struct FillRectWithRoundedCorners {
     Optional<Gfx::FloatPoint> aa_translation {};
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct FillPathUsingColor {
@@ -188,7 +162,6 @@ struct FillPathUsingColor {
     Optional<Gfx::FloatPoint> aa_translation {};
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return path_bounding_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct FillPathUsingPaintStyle {
@@ -200,7 +173,6 @@ struct FillPathUsingPaintStyle {
     Optional<Gfx::FloatPoint> aa_translation {};
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return path_bounding_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct StrokePathUsingColor {
@@ -211,7 +183,6 @@ struct StrokePathUsingColor {
     Optional<Gfx::FloatPoint> aa_translation {};
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return path_bounding_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct StrokePathUsingPaintStyle {
@@ -223,7 +194,6 @@ struct StrokePathUsingPaintStyle {
     Optional<Gfx::FloatPoint> aa_translation {};
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return path_bounding_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawEllipse {
@@ -232,7 +202,6 @@ struct DrawEllipse {
     int thickness;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct FillElipse {
@@ -241,7 +210,6 @@ struct FillElipse {
     Gfx::AntiAliasingPainter::BlendMode blend_mode;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawLine {
@@ -251,8 +219,6 @@ struct DrawLine {
     int thickness;
     Gfx::Painter::LineStyle style;
     Color alternate_color;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawSignedDistanceField {
@@ -262,7 +228,6 @@ struct DrawSignedDistanceField {
     float smoothing;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintProgressbar {
@@ -275,7 +240,6 @@ struct PaintProgressbar {
     StringView text;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return frame_rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintFrame {
@@ -284,7 +248,6 @@ struct PaintFrame {
     Gfx::FrameStyle style;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct ApplyBackdropFilter {
@@ -293,7 +256,6 @@ struct ApplyBackdropFilter {
     CSS::ResolvedBackdropFilter backdrop_filter;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return backdrop_region; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawRect {
@@ -302,7 +264,6 @@ struct DrawRect {
     bool rough;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintRadialGradient {
@@ -312,7 +273,6 @@ struct PaintRadialGradient {
     Gfx::IntSize size;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct PaintConicGradient {
@@ -321,7 +281,6 @@ struct PaintConicGradient {
     Gfx::IntPoint position;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const { return rect; }
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct DrawTriangleWave {
@@ -330,22 +289,18 @@ struct DrawTriangleWave {
     Color color;
     int amplitude;
     int thickness;
-
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct SampleUnderCorners {
     NonnullRefPtr<BorderRadiusCornerClipper> corner_clipper;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const;
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 struct BlitCornerClipping {
     NonnullRefPtr<BorderRadiusCornerClipper> corner_clipper;
 
     [[nodiscard]] Gfx::IntRect bounding_rect() const;
-    [[nodiscard]] CommandResult execute(CommandExecutionState&) const;
 };
 
 using PaintingCommand = Variant<
@@ -383,6 +338,47 @@ using PaintingCommand = Variant<
     SampleUnderCorners,
     BlitCornerClipping>;
 
+class PaintingCommandExecutor {
+public:
+    virtual ~PaintingCommandExecutor() = default;
+
+    virtual CommandResult draw_text_run(Color const&, Gfx::IntPoint const& baseline_start, String const&, Gfx::Font const&) = 0;
+    virtual CommandResult draw_text(Gfx::IntRect const&, String const&, Gfx::TextAlignment alignment, Color const&, Gfx::TextElision, Gfx::TextWrapping, Optional<NonnullRefPtr<Gfx::Font>> const&) = 0;
+    virtual CommandResult fill_rect(Gfx::IntRect const&, Color const&) = 0;
+    virtual CommandResult draw_scaled_bitmap(Gfx::IntRect const& dst_rect, Gfx::Bitmap const& bitmap, Gfx::IntRect const& src_rect, float opacity, Gfx::Painter::ScalingMode scaling_mode) = 0;
+    virtual CommandResult set_clip_rect(Gfx::IntRect const& rect) = 0;
+    virtual CommandResult clear_clip_rect() = 0;
+    virtual CommandResult set_font(Gfx::Font const& font) = 0;
+    virtual CommandResult push_stacking_context(bool semitransparent_or_has_non_identity_transform, float opacity, Gfx::FloatRect const& source_rect, Gfx::FloatRect const& transformed_destination_rect, Gfx::IntPoint const& painter_location) = 0;
+    virtual CommandResult pop_stacking_context(bool semitransparent_or_has_non_identity_transform, Gfx::Painter::ScalingMode scaling_mode) = 0;
+    virtual CommandResult push_stacking_context_with_mask(Gfx::IntRect const& paint_rect) = 0;
+    virtual CommandResult pop_stacking_context_with_mask(Gfx::IntRect const& paint_rect, RefPtr<Gfx::Bitmap> const& mask_bitmap, Gfx::Bitmap::MaskKind mask_kind, float opacity) = 0;
+    virtual CommandResult paint_linear_gradient(Gfx::IntRect const&, LinearGradientData const&) = 0;
+    virtual CommandResult paint_radial_gradient(Gfx::IntRect const& rect, RadialGradientData const&, Gfx::IntPoint const& center, Gfx::IntSize const& size) = 0;
+    virtual CommandResult paint_conic_gradient(Gfx::IntRect const& rect, ConicGradientData const&, Gfx::IntPoint const& position) = 0;
+    virtual CommandResult paint_outer_box_shadow(PaintOuterBoxShadowParams const&) = 0;
+    virtual CommandResult paint_inner_box_shadow(PaintOuterBoxShadowParams const&) = 0;
+    virtual CommandResult paint_text_shadow(int blur_radius, Gfx::IntRect const& shadow_bounding_rect, Gfx::IntRect const& text_rect, String const&, Gfx::Font const&, Color const&, int fragment_baseline, Gfx::IntPoint const& draw_location) = 0;
+    virtual CommandResult fill_rect_with_rounded_corners(Gfx::IntRect const& rect, Color const& color, Gfx::AntiAliasingPainter::CornerRadius const& top_left_radius, Gfx::AntiAliasingPainter::CornerRadius const& top_right_radius, Gfx::AntiAliasingPainter::CornerRadius const& bottom_left_radius, Gfx::AntiAliasingPainter::CornerRadius const& bottom_right_radius, Optional<Gfx::FloatPoint> const& aa_translation) = 0;
+    virtual CommandResult fill_path_using_color(Gfx::Path const&, Color const& color, Gfx::Painter::WindingRule, Optional<Gfx::FloatPoint> const& aa_translation) = 0;
+    virtual CommandResult fill_path_using_paint_style(Gfx::Path const&, Gfx::PaintStyle const& paint_style, Gfx::Painter::WindingRule winding_rule, float opacity, Optional<Gfx::FloatPoint> const& aa_translation) = 0;
+    virtual CommandResult stroke_path_using_color(Gfx::Path const&, Color const& color, float thickness, Optional<Gfx::FloatPoint> const& aa_translation) = 0;
+    virtual CommandResult stroke_path_using_paint_style(Gfx::Path const&, Gfx::PaintStyle const& paint_style, float thickness, float opacity, Optional<Gfx::FloatPoint> const& aa_translation) = 0;
+    virtual CommandResult draw_ellipse(Gfx::IntRect const&, Color const&, int thickness) = 0;
+    virtual CommandResult fill_ellipse(Gfx::IntRect const&, Color const&, Gfx::AntiAliasingPainter::BlendMode blend_mode) = 0;
+    virtual CommandResult draw_line(Color const& color, Gfx::IntPoint const& from, Gfx::IntPoint const& to, int thickness, Gfx::Painter::LineStyle, Color const& alternate_color) = 0;
+    virtual CommandResult draw_signed_distance_field(Gfx::IntRect const& rect, Color const&, Gfx::GrayscaleBitmap const&, float smoothing) = 0;
+    virtual CommandResult paint_progressbar(Gfx::IntRect const& frame_rect, Gfx::IntRect const& progress_rect, Palette const& palette, int min, int max, int value, StringView const& text) = 0;
+    virtual CommandResult paint_frame(Gfx::IntRect const& rect, Palette const&, Gfx::FrameStyle) = 0;
+    virtual CommandResult apply_backdrop_filter(Gfx::IntRect const& backdrop_region, Web::CSS::ResolvedBackdropFilter const& backdrop_filter) = 0;
+    virtual CommandResult draw_rect(Gfx::IntRect const& rect, Color const&, bool rough) = 0;
+    virtual CommandResult draw_triangle_wave(Gfx::IntPoint const& p1, Gfx::IntPoint const& p2, Color const& color, int amplitude, int thickness) = 0;
+    virtual CommandResult sample_under_corners(BorderRadiusCornerClipper&) = 0;
+    virtual CommandResult blit_corner_clipping(BorderRadiusCornerClipper&) = 0;
+
+    virtual bool would_be_fully_clipped_by_painter(Gfx::IntRect) const = 0;
+};
+
 class RecordingPainter {
 public:
     void fill_rect(Gfx::IntRect const& rect, Color color);
@@ -490,7 +486,7 @@ public:
 
     void draw_triangle_wave(Gfx::IntPoint a_p1, Gfx::IntPoint a_p2, Color color, int amplitude, int thickness);
 
-    void execute(Gfx::Bitmap&);
+    void execute(PaintingCommandExecutor&);
 
     RecordingPainter()
     {

Userland/Libraries/LibWeb/Painting/SVGGraphicsPaintable.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <LibWeb/Layout/ImageBox.h>
+#include <LibWeb/Painting/PaintingCommandExecutorCPU.h>
 #include <LibWeb/Painting/SVGGraphicsPaintable.h>
 #include <LibWeb/Painting/StackingContext.h>
 #include <LibWeb/SVG/SVGMaskElement.h>
@@ -96,7 +97,8 @@ RefPtr<Gfx::Bitmap> SVGGraphicsPaintable::calculate_mask(PaintContext& context,
             auto paint_context = context.clone(painter);
             paint_context.set_svg_transform(graphics_element.get_transform());
             StackingContext::paint_node_as_stacking_context(mask_paintable, paint_context);
-            painter.execute(*mask_bitmap);
+            PaintingCommandExecutorCPU executor { *mask_bitmap };
+            painter.execute(executor);
         }
     }
     return mask_bitmap;

Userland/Libraries/LibWeb/SVG/SVGDecodedImageData.cpp

@@ -15,6 +15,7 @@
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Page/Page.h>
 #include <LibWeb/Painting/PaintContext.h>
+#include <LibWeb/Painting/PaintingCommandExecutorCPU.h>
 #include <LibWeb/Painting/ViewportPaintable.h>
 #include <LibWeb/SVG/SVGDecodedImageData.h>
 #include <LibWeb/SVG/SVGSVGElement.h>
@@ -111,7 +112,8 @@ void SVGDecodedImageData::render(Gfx::IntSize size) const
 
     m_document->paintable()->paint_all_phases(context);
 
-    recording_painter.execute(*m_bitmap);
+    Painting::PaintingCommandExecutorCPU executor { *m_bitmap };
+    recording_painter.execute(executor);
 }
 
 RefPtr<Gfx::Bitmap const> SVGDecodedImageData::bitmap(size_t, Gfx::IntSize size) const

Userland/Services/WebContent/PageHost.cpp

@@ -15,6 +15,7 @@
 #include <LibWeb/HTML/TraversableNavigable.h>
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Painting/PaintableBox.h>
+#include <LibWeb/Painting/PaintingCommandExecutorCPU.h>
 #include <LibWeb/Painting/ViewportPaintable.h>
 #include <LibWeb/Platform/Timer.h>
 #include <WebContent/WebContentClientEndpoint.h>
@@ -144,7 +145,8 @@ void PageHost::paint(Web::DevicePixelRect const& content_rect, Gfx::Bitmap& targ
     context.set_has_focus(m_has_focus);
     document->paintable()->paint_all_phases(context);
 
-    recording_painter.execute(target);
+    Web::Painting::PaintingCommandExecutorCPU painting_command_executor(target);
+    recording_painter.execute(painting_command_executor);
 }
 
 void PageHost::set_viewport_rect(Web::DevicePixelRect const& rect)