ladybird/Userland/Libraries/LibWeb/Painting/SVGGraphicsPaintable.cpp
MacDue 163b6bb401 LibWeb: Special case SVG masks during layout
Rather than try to lay out masks normally, this updates the TreeBuilder
to create layout nodes for masks as a child of their user (i.e. the
masked element). This allows each use of a mask to be laid out
differently, which makes supporting `maskContentUnits=objectBoundingBox`
fairly easy.

The `SVGFormattingContext` is then updated to lay out masks last (as
their sizing may depend on their parent), and treats them like
viewports.

This is pretty ad-hoc, but the SVG specification does not give any
guidance on how to actually implement this.
2024-03-12 08:51:50 +01:00

88 lines
3.2 KiB
C++

/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Layout/ImageBox.h>
#include <LibWeb/Layout/SVGMaskBox.h>
#include <LibWeb/Painting/CommandExecutorCPU.h>
#include <LibWeb/Painting/SVGGraphicsPaintable.h>
#include <LibWeb/Painting/StackingContext.h>
#include <LibWeb/SVG/SVGMaskElement.h>
#include <LibWeb/SVG/SVGSVGElement.h>
namespace Web::Painting {
JS::NonnullGCPtr<SVGGraphicsPaintable> SVGGraphicsPaintable::create(Layout::SVGGraphicsBox const& layout_box)
{
return layout_box.heap().allocate_without_realm<SVGGraphicsPaintable>(layout_box);
}
SVGGraphicsPaintable::SVGGraphicsPaintable(Layout::SVGGraphicsBox const& layout_box)
: SVGPaintable(layout_box)
{
}
Layout::SVGGraphicsBox const& SVGGraphicsPaintable::layout_box() const
{
return static_cast<Layout::SVGGraphicsBox const&>(layout_node());
}
Optional<CSSPixelRect> SVGGraphicsPaintable::get_masking_area() const
{
auto const& graphics_element = verify_cast<SVG::SVGGraphicsElement const>(*dom_node());
auto* mask_box = graphics_element.layout_node()->first_child_of_type<Layout::SVGMaskBox>();
if (!mask_box)
return {};
return mask_box->dom_node().resolve_masking_area(mask_box->paintable_box()->absolute_border_box_rect());
}
static Gfx::Bitmap::MaskKind mask_type_to_gfx_mask_kind(CSS::MaskType mask_type)
{
switch (mask_type) {
case CSS::MaskType::Alpha:
return Gfx::Bitmap::MaskKind::Alpha;
case CSS::MaskType::Luminance:
return Gfx::Bitmap::MaskKind::Luminance;
default:
VERIFY_NOT_REACHED();
}
}
Optional<Gfx::Bitmap::MaskKind> SVGGraphicsPaintable::get_mask_type() const
{
auto const& graphics_element = verify_cast<SVG::SVGGraphicsElement const>(*dom_node());
auto mask = graphics_element.mask();
if (!mask)
return {};
return mask_type_to_gfx_mask_kind(mask->layout_node()->computed_values().mask_type());
}
RefPtr<Gfx::Bitmap> SVGGraphicsPaintable::calculate_mask(PaintContext& context, CSSPixelRect const& masking_area) const
{
auto const& graphics_element = verify_cast<SVG::SVGGraphicsElement const>(*dom_node());
auto* mask_box = graphics_element.layout_node()->first_child_of_type<Layout::SVGMaskBox>();
VERIFY(mask_box);
auto mask_rect = context.enclosing_device_rect(masking_area);
RefPtr<Gfx::Bitmap> mask_bitmap = {};
auto& mask_paintable = static_cast<PaintableBox const&>(*mask_box->paintable());
auto mask_bitmap_or_error = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, mask_rect.size().to_type<int>());
if (mask_bitmap_or_error.is_error())
return {};
mask_bitmap = mask_bitmap_or_error.release_value();
{
CommandList painting_commands;
RecordingPainter recording_painter(painting_commands);
recording_painter.translate(-mask_rect.location().to_type<int>());
auto paint_context = context.clone(recording_painter);
paint_context.set_svg_transform(graphics_element.get_transform());
StackingContext::paint_node_as_stacking_context(mask_paintable, paint_context);
CommandExecutorCPU executor { *mask_bitmap };
painting_commands.execute(executor);
}
return mask_bitmap;
}
}