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LibWeb: Resolve and paint simple SVG masks

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This allows applying SVG <mask>s to elements. It is only implemented for
the simplest (and default) case:

	- mask-type = luminance
 	- maskContentUnits = maskContentUnits
 	- maskUnits = objectBoundingBox
	- Default masking area

It should be possible to extend to cover more cases. Though the layout
for maskContentUnits = objectBoundingBox will be tricky to figure out.
This commit is contained in:
MacDue 2023-09-10 14:10:55 +01:00 • committed by Andreas Kling
parent 650180811e
commit 909bcfe9a4
12 changed files with 123 additions and 17 deletions
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40
Userland/Libraries/LibWeb/Painting/SVGGraphicsPaintable.cpp
View file

@ -6,6 +6,7 @@
#include <LibWeb/Layout/ImageBox.h>
#include <LibWeb/Painting/SVGGraphicsPaintable.h>
#include <LibWeb/Painting/StackingContext.h>
#include <LibWeb/SVG/SVGMaskElement.h>
namespace Web::Painting {
@ -31,4 +32,43 @@ 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());
if (auto mask = graphics_element.mask())
return mask->resolve_masking_area(absolute_border_box_rect());
return {};
}
void SVGGraphicsPaintable::apply_mask(PaintContext& context, Gfx::Bitmap& target, CSSPixelRect const& masking_area) const
{
auto const& graphics_element = verify_cast<SVG::SVGGraphicsElement const>(*dom_node());
auto mask = graphics_element.mask();
VERIFY(mask);
if (mask->mask_content_units() != SVG::MaskContentUnits::UserSpaceOnUse) {
dbgln("SVG: maskContentUnits=objectBoundingBox is not supported");
return;
}
auto mask_rect = context.enclosing_device_rect(masking_area);
RefPtr<Gfx::Bitmap> mask_bitmap = {};
if (mask && mask->layout_node() && is<PaintableBox>(mask->layout_node()->paintable())) {
auto& mask_paintable = static_cast<PaintableBox const&>(*mask->layout_node()->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();
{
Gfx::Painter painter(*mask_bitmap);
painter.translate(-mask_rect.location().to_type<int>());
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);
}
}
// TODO: Follow mask-type attribute to select between alpha/luminance masks.
if (mask_bitmap)
target.apply_mask(*mask_bitmap, Gfx::Bitmap::MaskKind::Luminance);
return;
}
}