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ladybird/Libraries/LibWeb/CSS/Transformation.cpp
Jelle Raaijmakers 15fa6676b0 LibWeb: Simplify generation of perspective() matrix transform 
A value of `perspective(none)` should result in the identity matrix. But
instead of creating that identity matrix explicitly, just break and
default to the identity matrix at the bottom of this method.
2025-11-18 14:36:26 +01:00

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/*
* Copyright (c) 2020-2022, Andreas Kling <andreas@ladybird.org>
* Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
* Copyright (c) 2024-2025, Bastiaan van der Plaat <bastiaan.v.d.plaat@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "Transformation.h"
#include <LibWeb/Painting/PaintableBox.h>
namespace Web::CSS {
Transformation::Transformation(TransformFunction function, Vector<TransformValue>&& values)
: m_function(function)
, m_values(move(values))
{
}
ErrorOr<Gfx::FloatMatrix4x4> Transformation::to_matrix(Optional<Painting::PaintableBox const&> paintable_box) const
{
auto count = m_values.size();
auto value = [&](size_t index, CSSPixels const& reference_length = 0) -> ErrorOr<float> {
CalculationResolutionContext context {};
if (paintable_box.has_value())
context.length_resolution_context = Length::ResolutionContext::for_layout_node(paintable_box->layout_node());
return m_values[index].visit(
[&](CSS::AngleOrCalculated const& value) -> ErrorOr<float> {
if (!value.is_calculated())
return fmod(value.value().to_radians(), 2 * AK::Pi<double>);
if (auto resolved = value.resolved(context); resolved.has_value())
return fmod(resolved->to_radians(), 2 * AK::Pi<double>);
return Error::from_string_literal("Transform contains non absolute units");
},
[&](CSS::LengthPercentage const& value) -> ErrorOr<float> {
context.percentage_basis = Length::make_px(reference_length);
if (paintable_box.has_value())
return value.resolved(paintable_box->layout_node(), reference_length).to_px(paintable_box->layout_node()).to_float();
if (value.is_length()) {
if (auto const& length = value.length(); length.is_absolute())
return length.absolute_length_to_px().to_float();
}
if (value.is_calculated() && value.calculated()->resolves_to_length()) {
if (auto const& resolved = value.calculated()->resolve_length(context); resolved.has_value() && resolved->is_absolute())
return resolved->absolute_length_to_px().to_float();
}
return Error::from_string_literal("Transform contains non absolute units");
},
[&](CSS::NumberPercentage const& value) -> ErrorOr<float> {
if (value.is_number())
return value.number().value();
if (value.is_percentage())
return value.percentage().as_fraction();
if (value.is_calculated()) {
if (value.calculated()->resolves_to_number())
if (auto resolved_number = value.calculated()->resolve_number(context); resolved_number.has_value())
return resolved_number.value();
if (value.calculated()->resolves_to_percentage())
if (auto resolved_percentage = value.calculated()->resolve_percentage(context); resolved_percentage.has_value())
return resolved_percentage->as_fraction();
}
return Error::from_string_literal("Transform contains non absolute units");
});
};
CSSPixels width = 1;
CSSPixels height = 1;
if (paintable_box.has_value()) {
auto reference_box = paintable_box->transform_box_rect();
width = reference_box.width();
height = reference_box.height();
}
switch (m_function) {
case CSS::TransformFunction::Perspective:
// https://drafts.csswg.org/css-transforms-2/#funcdef-perspective
// Count is zero when null parameter
if (count == 1) {
auto distance = TRY(value(0));
// If the depth value is less than '1px', it must be treated as '1px' for the purpose of rendering, for
// computing the resolved value of 'transform', and when used as the endpoint of interpolation.
// Note: The intent of the above rules on values less than '1px' is that they cover the cases where
// the 'perspective()' function needs to be converted into a matrix.
if (distance < 1)
distance = 1;
return Gfx::FloatMatrix4x4(1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, -1 / distance, 1);
}
break;
case CSS::TransformFunction::Matrix:
if (count == 6)
return Gfx::FloatMatrix4x4(TRY(value(0)), TRY(value(2)), 0, TRY(value(4)),
TRY(value(1)), TRY(value(3)), 0, TRY(value(5)),
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::Matrix3d:
if (count == 16)
return Gfx::FloatMatrix4x4(TRY(value(0)), TRY(value(4)), TRY(value(8)), TRY(value(12)),
TRY(value(1)), TRY(value(5)), TRY(value(9)), TRY(value(13)),
TRY(value(2)), TRY(value(6)), TRY(value(10)), TRY(value(14)),
TRY(value(3)), TRY(value(7)), TRY(value(11)), TRY(value(15)));
break;
case CSS::TransformFunction::Translate:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, TRY(value(0, width)),
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
if (count == 2)
return Gfx::FloatMatrix4x4(1, 0, 0, TRY(value(0, width)),
0, 1, 0, TRY(value(1, height)),
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::Translate3d:
return Gfx::FloatMatrix4x4(1, 0, 0, TRY(value(0, width)),
0, 1, 0, TRY(value(1, height)),
0, 0, 1, TRY(value(2)),
0, 0, 0, 1);
case CSS::TransformFunction::TranslateX:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, TRY(value(0, width)),
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::TranslateY:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, 0,
0, 1, 0, TRY(value(0, height)),
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::TranslateZ:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, TRY(value(0)),
0, 0, 0, 1);
break;
case CSS::TransformFunction::Scale:
if (count == 1)
return Gfx::FloatMatrix4x4(TRY(value(0)), 0, 0, 0,
0, TRY(value(0)), 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
if (count == 2)
return Gfx::FloatMatrix4x4(TRY(value(0)), 0, 0, 0,
0, TRY(value(1)), 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::Scale3d:
if (count == 3)
return Gfx::FloatMatrix4x4(TRY(value(0)), 0, 0, 0,
0, TRY(value(1)), 0, 0,
0, 0, TRY(value(2)), 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::ScaleX:
if (count == 1)
return Gfx::FloatMatrix4x4(TRY(value(0)), 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::ScaleY:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, 0,
0, TRY(value(0)), 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::ScaleZ:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, 0,
0, 1, 0, 0,
0, 0, TRY(value(0)), 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::Rotate3d:
if (count == 4)
return Gfx::rotation_matrix({ TRY(value(0)), TRY(value(1)), TRY(value(2)) }, TRY(value(3)));
break;
case CSS::TransformFunction::RotateX:
if (count == 1)
return Gfx::rotation_matrix({ 1.0f, 0.0f, 0.0f }, TRY(value(0)));
break;
case CSS::TransformFunction::RotateY:
if (count == 1)
return Gfx::rotation_matrix({ 0.0f, 1.0f, 0.0f }, TRY(value(0)));
break;
case CSS::TransformFunction::Rotate:
case CSS::TransformFunction::RotateZ:
if (count == 1)
return Gfx::rotation_matrix({ 0.0f, 0.0f, 1.0f }, TRY(value(0)));
break;
case CSS::TransformFunction::Skew:
if (count == 1)
return Gfx::FloatMatrix4x4(1, tanf(TRY(value(0))), 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
if (count == 2)
return Gfx::FloatMatrix4x4(1, tanf(TRY(value(0))), 0, 0,
tanf(TRY(value(1))), 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::SkewX:
if (count == 1)
return Gfx::FloatMatrix4x4(1, tanf(TRY(value(0))), 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
case CSS::TransformFunction::SkewY:
if (count == 1)
return Gfx::FloatMatrix4x4(1, 0, 0, 0,
tanf(TRY(value(0))), 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1);
break;
}
dbgln_if(LIBWEB_CSS_DEBUG, "FIXME: Unhandled transformation function {} with {} arguments", to_string(m_function), m_values.size());
return Gfx::FloatMatrix4x4::identity();
}
}
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