LibWeb: Introduce color-function-specific style values

Instead of CSSColorValue holding a Gfx::Color, make it an abstract class
with subclasses for each different color function, to match the Typed-OM
spec. This means moving the color calculations from the parsing code to
the `to_color()` method on the style value.

This lets us have calc() inside a color function, instead of having to
fully resolve the color at parse time. The canvas fillStyle tests have
been updated to reflect this.

The other test change is Screenshot/css-color-functions.html: previously
we produced slightly different colors for an alpha of 0.5 and one of
50%, and this incorrect behavior was baked into the test. So now it's
more correct. :^)
This commit is contained in:
Sam Atkins 2024-08-16 16:42:16 +01:00 committed by Sam Atkins
commit 3af6a69f1e
Notes: github-actions[bot] 2024-08-21 09:52:45 +00:00
24 changed files with 1108 additions and 496 deletions

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/*
* Copyright (c) 2024, Sam Atkins <sam@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "CSSOKLab.h"
#include <AK/TypeCasts.h>
#include <LibWeb/CSS/Serialize.h>
#include <LibWeb/CSS/StyleValues/CalculatedStyleValue.h>
#include <LibWeb/CSS/StyleValues/NumberStyleValue.h>
#include <LibWeb/CSS/StyleValues/PercentageStyleValue.h>
namespace Web::CSS {
Color CSSOKLab::to_color(Optional<Layout::NodeWithStyle const&>) const
{
auto const l_val = clamp(resolve_with_reference_value(m_properties.l, 1.0).value_or(0), 0, 1);
auto const a_val = resolve_with_reference_value(m_properties.a, 0.4).value_or(0);
auto const b_val = resolve_with_reference_value(m_properties.b, 0.4).value_or(0);
auto const alpha_val = resolve_alpha(m_properties.alpha).value_or(1);
return Color::from_oklab(l_val, a_val, b_val, alpha_val);
}
bool CSSOKLab::equals(CSSStyleValue const& other) const
{
if (type() != other.type())
return false;
auto const& other_color = other.as_color();
if (color_type() != other_color.color_type())
return false;
auto const& other_oklab = verify_cast<CSSOKLab>(other_color);
return m_properties == other_oklab.m_properties;
}
// https://www.w3.org/TR/css-color-4/#serializing-oklab-oklch
String CSSOKLab::to_string() const
{
// FIXME: Do this properly, taking unresolved calculated values into account.
return serialize_a_srgb_value(to_color({}));
}
}