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/*
* Copyright (C) 2025 Samuel Weinig <sam@webkit.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <WebCore/AnimationUtilities.h>
#include <WebCore/StyleCalculationValue.h>
#include <WebCore/StyleLengthWrapper.h>
namespace WebCore {
namespace Style {
// MARK: - Blending
static constexpr size_t maximumBlendTreeDepth = 128;
template<typename T> struct LengthWrapperBlendingSupport {
static auto blendMixedSpecifiedTypes(const T& a, const T& b, const BlendingContext& context) -> T
{
ASSERT(a.isSpecified());
ASSERT(b.isSpecified());
auto copyCalculation = [](const T& value) -> Calculation::Child {
if (value.isPercent())
return Calculation::percentage(value.m_value.value());
if (value.isCalculated())
return value.m_value.protectedCalculationValue()->copyRoot();
ASSERT(value.isFixed());
return Calculation::dimension(value.m_value.value());
};
auto isTooDeepToBlendWithNode = [](const T& value) {
if (!value.isCalculated())
return false;
auto treeDepth = computeDepth(value.m_value.protectedCalculationValue()->tree());
return treeDepth > maximumBlendTreeDepth;
};
if (context.compositeOperation != CompositeOperation::Replace)
return typename T::Calc { Calculation::add(copyCalculation(a), copyCalculation(b)) };
auto isFixedZero = [](const T& value) {
ASSERT(value.isFixed() || value.isCalculated());
if (auto fixed = value.tryFixed())
return fixed->isZero();
return false;
};
if (!b.isCalculated() && !a.isPercent() && (context.progress == 1 || isFixedZero(a))) {
if (b.isPercent())
return Style::blend(typename T::Percentage { 0 }, typename T::Percentage { b.m_value.value() }, context);
return Style::blend(typename T::Fixed { 0 }, typename T::Fixed { b.m_value.value() }, context);
}
if (!a.isCalculated() && !b.isPercent() && (!context.progress || isFixedZero(b))) {
if (a.isPercent())
return Style::blend(typename T::Percentage { a.m_value.value() }, typename T::Percentage { 0 }, context);
return Style::blend(typename T::Fixed { a.m_value.value() }, typename T::Fixed { 0 }, context);
}
// Limit the tree depth generated by blending to avoid blowing up the stack in recursive functions.
if (isTooDeepToBlendWithNode(a) || isTooDeepToBlendWithNode(b))
return typename T::Calc { copyCalculation(b) };
return typename T::Calc { Calculation::blend(copyCalculation(a), copyCalculation(b), context.progress) };
}
};
template<LengthWrapperBaseDerived T> struct Blending<T> {
auto canBlend(const T& a, const T& b) -> bool
{
return a.hasSameType(b) || (a.isSpecified() && b.isSpecified());
}
auto requiresInterpolationForAccumulativeIteration(const T& a, const T& b) -> bool
{
return !a.hasSameType(b) || a.isCalculated() || b.isCalculated();
}
auto blend(const T& a, const T& b, const BlendingContext& context) -> T
{
if (!a.isSpecified() || !b.isSpecified())
return context.progress < 0.5 ? a : b;
if (a.isCalculated() || b.isCalculated() || !a.hasSameType(b))
return LengthWrapperBlendingSupport<T>::blendMixedSpecifiedTypes(a, b, context);
if (!context.progress && context.isReplace())
return a;
if (context.progress == 1 && context.isReplace())
return b;
auto resultType = b.m_value.type();
ASSERT(resultType == T::indexForPercentage || resultType == T::indexForFixed);
if (resultType == T::indexForPercentage) {
return Style::blend(
typename T::Percentage { a.m_value.value() },
typename T::Percentage { b.m_value.value() },
context
);
} else {
return Style::blend(
typename T::Fixed { a.m_value.value() },
typename T::Fixed { b.m_value.value() },
context
);
}
}
};
} // namespace Style
} // namespace WebCore
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