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serenity/Userland/Libraries/LibWeb/Painting/ShadowPainting.cpp
Sam Atkins 10c6c77b5c LibWeb: Render multiple box-shadows
Because why not? :^)
2022-02-08 17:45:51 +01:00

62 lines
2.3 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021-2022, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibGfx/DisjointRectSet.h>
#include <LibGfx/Filters/FastBoxBlurFilter.h>
#include <LibGfx/Painter.h>
#include <LibWeb/Painting/PaintContext.h>
#include <LibWeb/Painting/ShadowPainting.h>
namespace Web::Painting {
void paint_box_shadow(PaintContext& context, Gfx::IntRect const& content_rect, Vector<BoxShadowData> const& box_shadow_layers)
{
if (box_shadow_layers.is_empty())
return;
// Note: Box-shadow layers are ordered front-to-back, so we paint them in reverse
for (int layer_index = box_shadow_layers.size() - 1; layer_index >= 0; layer_index--) {
auto& box_shadow_data = box_shadow_layers[layer_index];
Gfx::IntRect bitmap_rect = {
0,
0,
content_rect.width() + 4 * box_shadow_data.blur_radius,
content_rect.height() + 4 * box_shadow_data.blur_radius
};
Gfx::IntPoint blur_rect_position = {
content_rect.x() - 2 * box_shadow_data.blur_radius + box_shadow_data.offset_x,
content_rect.y() - 2 * box_shadow_data.blur_radius + box_shadow_data.offset_y
};
if (bitmap_rect.is_empty())
return;
auto bitmap_or_error = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, bitmap_rect.size());
if (bitmap_or_error.is_error()) {
dbgln("Unable to allocate temporary bitmap for box-shadow rendering: {}", bitmap_or_error.error());
return;
}
auto new_bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
Gfx::Painter painter(*new_bitmap);
painter.fill_rect({ { 2 * box_shadow_data.blur_radius, 2 * box_shadow_data.blur_radius }, content_rect.size() }, box_shadow_data.color);
Gfx::FastBoxBlurFilter filter(*new_bitmap);
filter.apply_three_passes(box_shadow_data.blur_radius);
Gfx::DisjointRectSet rect_set;
rect_set.add(bitmap_rect);
auto shattered = rect_set.shatter({ content_rect.location() - blur_rect_position, content_rect.size() });
for (auto& rect : shattered.rects())
context.painter().blit(rect.location() + blur_rect_position, *new_bitmap, rect);
}
}
}