LibWeb: Simplify outer box shadow's bounding box calculation

There is no need in the overly complicated OuterBoxShadowMetrics after
switching to use Skia for painting.

Userland/Libraries/LibWeb/Painting/Command.cpp

@@ -17,7 +17,13 @@ void DrawGlyphRun::translate_by(Gfx::IntPoint const& offset)
 
 Gfx::IntRect PaintOuterBoxShadow::bounding_rect() const
 {
-    return get_outer_box_shadow_bounding_rect(box_shadow_params);
+    auto shadow_rect = box_shadow_params.device_content_rect;
+    auto spread = box_shadow_params.blur_radius * 2 + box_shadow_params.spread_distance;
+    shadow_rect.inflate(spread, spread, spread, spread);
+    auto offset_x = box_shadow_params.offset_x;
+    auto offset_y = box_shadow_params.offset_y;
+    shadow_rect.translate_by(offset_x, offset_y);
+    return shadow_rect;
 }
 
 Gfx::IntRect PaintInnerBoxShadow::bounding_rect() const

Userland/Libraries/LibWeb/Painting/ShadowPainting.cpp

@@ -6,12 +6,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/NumericLimits.h>
 #include <LibGfx/DisjointRectSet.h>
-#include <LibGfx/Font/Font.h>
 #include <LibGfx/Painter.h>
-#include <LibWeb/Layout/LineBoxFragment.h>
-#include <LibWeb/Layout/Node.h>
 #include <LibWeb/Painting/BorderPainting.h>
 #include <LibWeb/Painting/BorderRadiusCornerClipper.h>
 #include <LibWeb/Painting/PaintBoxShadowParams.h>
@@ -21,238 +17,6 @@
 
 namespace Web::Painting {
 
-struct OuterBoxShadowMetrics {
-    Gfx::IntRect shadow_bitmap_rect;
-    Gfx::IntRect non_blurred_shadow_rect;
-    Gfx::IntRect inner_bounding_rect;
-    int blurred_edge_thickness;
-    int double_radius;
-    int blur_radius;
-
-    Gfx::IntRect top_left_corner_rect;
-    Gfx::IntRect top_right_corner_rect;
-    Gfx::IntRect bottom_right_corner_rect;
-    Gfx::IntRect bottom_left_corner_rect;
-
-    Gfx::IntPoint top_left_corner_blit_pos;
-    Gfx::IntPoint top_right_corner_blit_pos;
-    Gfx::IntPoint bottom_right_corner_blit_pos;
-    Gfx::IntPoint bottom_left_corner_blit_pos;
-
-    Gfx::IntSize top_left_corner_size;
-    Gfx::IntSize top_right_corner_size;
-    Gfx::IntSize bottom_right_corner_size;
-    Gfx::IntSize bottom_left_corner_size;
-
-    int left_start;
-    int top_start;
-    int right_start;
-    int bottom_start;
-
-    Gfx::IntRect left_edge_rect;
-    Gfx::IntRect right_edge_rect;
-    Gfx::IntRect top_edge_rect;
-    Gfx::IntRect bottom_edge_rect;
-
-    CornerRadius top_left_shadow_corner;
-    CornerRadius top_right_shadow_corner;
-    CornerRadius bottom_right_shadow_corner;
-    CornerRadius bottom_left_shadow_corner;
-};
-
-static OuterBoxShadowMetrics get_outer_box_shadow_configuration(PaintBoxShadowParams params)
-{
-    auto device_content_rect = params.device_content_rect;
-
-    auto top_left_corner = params.corner_radii.top_left;
-    auto top_right_corner = params.corner_radii.top_right;
-    auto bottom_right_corner = params.corner_radii.bottom_right;
-    auto bottom_left_corner = params.corner_radii.bottom_left;
-
-    auto offset_x = params.offset_x;
-    auto offset_y = params.offset_y;
-    auto blur_radius = params.blur_radius;
-    auto spread_distance = params.spread_distance;
-
-    // Our blur cannot handle radii over 255 so there's no point trying (255 is silly big anyway)
-    blur_radius = clamp(blur_radius, 0, 255);
-
-    auto top_left_shadow_corner = top_left_corner;
-    auto top_right_shadow_corner = top_right_corner;
-    auto bottom_right_shadow_corner = bottom_right_corner;
-    auto bottom_left_shadow_corner = bottom_left_corner;
-
-    auto spread_corner = [&](auto& corner) {
-        if (corner) {
-            corner.horizontal_radius += spread_distance;
-            corner.vertical_radius += spread_distance;
-        }
-    };
-
-    spread_corner(top_left_shadow_corner);
-    spread_corner(top_right_shadow_corner);
-    spread_corner(bottom_right_shadow_corner);
-    spread_corner(bottom_left_shadow_corner);
-
-    auto expansion = spread_distance - (blur_radius * 2);
-    Gfx::IntRect inner_bounding_rect = {
-        device_content_rect.x() + offset_x - expansion,
-        device_content_rect.y() + offset_y - expansion,
-        device_content_rect.width() + 2 * expansion,
-        device_content_rect.height() + 2 * expansion
-    };
-
-    // Calculating and blurring the box-shadow full size is expensive, and wasteful - aside from the corners,
-    // all vertical strips of the shadow are identical, and the same goes for horizontal ones.
-    // So instead, we generate a shadow bitmap that is just large enough to include the corners and 1px of
-    // non-corner, and then we repeatedly blit sections of it. This is similar to a NinePatch on Android.
-    auto double_radius = blur_radius * 2;
-    auto blurred_edge_thickness = blur_radius * 4;
-
-    auto default_corner_size = Gfx::IntSize { double_radius, double_radius };
-    auto top_left_corner_size = top_left_shadow_corner ? top_left_shadow_corner.as_rect().size() : default_corner_size;
-    auto top_right_corner_size = top_right_shadow_corner ? top_right_shadow_corner.as_rect().size() : default_corner_size;
-    auto bottom_left_corner_size = bottom_left_shadow_corner ? bottom_left_shadow_corner.as_rect().size() : default_corner_size;
-    auto bottom_right_corner_size = bottom_right_shadow_corner ? bottom_right_shadow_corner.as_rect().size() : default_corner_size;
-
-    auto non_blurred_shadow_rect = device_content_rect.inflated(spread_distance, spread_distance, spread_distance, spread_distance);
-
-    auto max_edge_width = non_blurred_shadow_rect.width() / 2;
-    auto max_edge_height = non_blurred_shadow_rect.height() / 2;
-    auto extra_edge_width = non_blurred_shadow_rect.width() % 2;
-    auto extra_edge_height = non_blurred_shadow_rect.height() % 2;
-
-    auto clip_corner_size = [&](auto& size, auto const& corner, int x_bonus = 0, int y_bonus = 0) {
-        auto max_x = max_edge_width + x_bonus;
-        auto max_y = max_edge_height + y_bonus;
-        auto min_x = max(corner.horizontal_radius, min(double_radius, max_x));
-        auto min_y = max(corner.vertical_radius, min(double_radius, max_y));
-        if (min_x <= max_x)
-            size.set_width(clamp(size.width(), min_x, max_x));
-        if (min_y <= max_y)
-            size.set_height(clamp(size.height(), min_y, max_y));
-    };
-
-    clip_corner_size(top_left_corner_size, top_left_corner, extra_edge_width, extra_edge_height);
-    clip_corner_size(top_right_corner_size, top_right_corner, 0, extra_edge_height);
-    clip_corner_size(bottom_left_corner_size, bottom_left_corner, extra_edge_width);
-    clip_corner_size(bottom_right_corner_size, bottom_right_corner);
-
-    auto shadow_bitmap_rect = Gfx::IntRect {
-        0, 0,
-        max(max(
-                top_left_corner_size.width() + top_right_corner_size.width(),
-                bottom_left_corner_size.width() + bottom_right_corner_size.width()),
-            max(top_left_corner_size.width() + bottom_right_corner_size.width(),
-                bottom_left_corner_size.width() + top_right_corner_size.width()))
-            + 1 + blurred_edge_thickness,
-        max(max(
-                top_left_corner_size.height() + bottom_left_corner_size.height(),
-                top_right_corner_size.height() + bottom_right_corner_size.height()),
-            max(top_left_corner_size.height() + bottom_right_corner_size.height(),
-                bottom_left_corner_size.height() + top_right_corner_size.height()))
-            + 1 + blurred_edge_thickness
-    };
-
-    auto top_left_corner_rect = Gfx::IntRect {
-        0, 0,
-        top_left_corner_size.width() + double_radius,
-        top_left_corner_size.height() + double_radius
-    };
-    auto top_right_corner_rect = Gfx::IntRect {
-        shadow_bitmap_rect.width() - (top_right_corner_size.width() + double_radius), 0,
-        top_right_corner_size.width() + double_radius,
-        top_right_corner_size.height() + double_radius
-    };
-    auto bottom_right_corner_rect = Gfx::IntRect {
-        shadow_bitmap_rect.width() - (bottom_right_corner_size.width() + double_radius),
-        shadow_bitmap_rect.height() - (bottom_right_corner_size.height() + double_radius),
-        bottom_right_corner_size.width() + double_radius,
-        bottom_right_corner_size.height() + double_radius
-    };
-    auto bottom_left_corner_rect = Gfx::IntRect {
-        0, shadow_bitmap_rect.height() - (bottom_left_corner_size.height() + double_radius),
-        bottom_left_corner_size.width() + double_radius,
-        bottom_left_corner_size.height() + double_radius
-    };
-
-    auto horizontal_edge_width = min(max_edge_height, double_radius) + double_radius;
-    auto vertical_edge_width = min(max_edge_width, double_radius) + double_radius;
-    auto horizontal_top_edge_width = min(max_edge_height + extra_edge_height, double_radius) + double_radius;
-    auto vertical_left_edge_width = min(max_edge_width + extra_edge_width, double_radius) + double_radius;
-
-    Gfx::IntRect left_edge_rect { 0, top_left_corner_rect.height(), vertical_left_edge_width, 1 };
-    Gfx::IntRect right_edge_rect { shadow_bitmap_rect.width() - vertical_edge_width, top_right_corner_rect.height(), vertical_edge_width, 1 };
-    Gfx::IntRect top_edge_rect { top_left_corner_rect.width(), 0, 1, horizontal_top_edge_width };
-    Gfx::IntRect bottom_edge_rect { bottom_left_corner_rect.width(), shadow_bitmap_rect.height() - horizontal_edge_width, 1, horizontal_edge_width };
-
-    auto left_start = inner_bounding_rect.left() - blurred_edge_thickness;
-    auto right_start = inner_bounding_rect.left() + inner_bounding_rect.width() + (blurred_edge_thickness - vertical_edge_width);
-    auto top_start = inner_bounding_rect.top() - blurred_edge_thickness;
-    auto bottom_start = inner_bounding_rect.top() + inner_bounding_rect.height() + (blurred_edge_thickness - horizontal_edge_width);
-
-    auto top_left_corner_blit_pos = inner_bounding_rect.top_left().translated(-blurred_edge_thickness, -blurred_edge_thickness);
-    auto top_right_corner_blit_pos = inner_bounding_rect.top_right().translated(-top_right_corner_size.width() + double_radius, -blurred_edge_thickness);
-    auto bottom_left_corner_blit_pos = inner_bounding_rect.bottom_left().translated(-blurred_edge_thickness, -bottom_left_corner_size.height() + double_radius);
-    auto bottom_right_corner_blit_pos = inner_bounding_rect.bottom_right().translated(-bottom_right_corner_size.width() + double_radius, -bottom_right_corner_size.height() + double_radius);
-
-    return OuterBoxShadowMetrics {
-        .shadow_bitmap_rect = shadow_bitmap_rect,
-        .non_blurred_shadow_rect = non_blurred_shadow_rect,
-        .inner_bounding_rect = inner_bounding_rect,
-        .blurred_edge_thickness = blurred_edge_thickness,
-        .double_radius = double_radius,
-        .blur_radius = blur_radius,
-
-        .top_left_corner_rect = top_left_corner_rect,
-        .top_right_corner_rect = top_right_corner_rect,
-        .bottom_right_corner_rect = bottom_right_corner_rect,
-        .bottom_left_corner_rect = bottom_left_corner_rect,
-
-        .top_left_corner_blit_pos = top_left_corner_blit_pos,
-        .top_right_corner_blit_pos = top_right_corner_blit_pos,
-        .bottom_right_corner_blit_pos = bottom_right_corner_blit_pos,
-        .bottom_left_corner_blit_pos = bottom_left_corner_blit_pos,
-
-        .top_left_corner_size = top_left_corner_size,
-        .top_right_corner_size = top_right_corner_size,
-        .bottom_right_corner_size = bottom_right_corner_size,
-        .bottom_left_corner_size = bottom_left_corner_size,
-
-        .left_start = left_start,
-        .top_start = top_start,
-        .right_start = right_start,
-        .bottom_start = bottom_start,
-
-        .left_edge_rect = left_edge_rect,
-        .right_edge_rect = right_edge_rect,
-        .top_edge_rect = top_edge_rect,
-        .bottom_edge_rect = bottom_edge_rect,
-
-        .top_left_shadow_corner = top_left_shadow_corner,
-        .top_right_shadow_corner = top_right_shadow_corner,
-        .bottom_right_shadow_corner = bottom_right_shadow_corner,
-        .bottom_left_shadow_corner = bottom_left_shadow_corner,
-    };
-}
-
-Gfx::IntRect get_outer_box_shadow_bounding_rect(PaintBoxShadowParams params)
-{
-    auto shadow_config = get_outer_box_shadow_configuration(params);
-
-    auto const& top_left_corner_blit_pos = shadow_config.top_left_corner_blit_pos;
-    auto const& top_right_corner_blit_pos = shadow_config.top_right_corner_blit_pos;
-    auto const& bottom_left_corner_blit_pos = shadow_config.bottom_left_corner_blit_pos;
-    auto const& top_right_corner_rect = shadow_config.top_right_corner_rect;
-    auto const& bottom_left_corner_rect = shadow_config.bottom_left_corner_rect;
-
-    return Gfx::IntRect {
-        top_left_corner_blit_pos,
-        { top_right_corner_blit_pos.x() - top_left_corner_blit_pos.x() + top_right_corner_rect.width(),
-            bottom_left_corner_blit_pos.y() - top_left_corner_blit_pos.y() + bottom_left_corner_rect.height() }
-    };
-}
-
 void paint_box_shadow(PaintContext& context,
     CSSPixelRect const& bordered_content_rect,
     CSSPixelRect const& borderless_content_rect,

Userland/Libraries/LibWeb/Painting/ShadowPainting.h

@@ -15,8 +15,6 @@
 
 namespace Web::Painting {
 
-Gfx::IntRect get_outer_box_shadow_bounding_rect(PaintBoxShadowParams params);
-
 void paint_box_shadow(
     PaintContext&,
     CSSPixelRect const& bordered_content_rect,