Source/WebCore/platform/graphics/transforms/PerspectiveTransformOperation.cpp

/*
 * Copyright (C) 2009 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
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 *
 * 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 COMPUTER, INC. OR
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#include "config.h"
#include "PerspectiveTransformOperation.h"

#include "AnimationUtilities.h"
#include <wtf/MathExtras.h>

using namespace std;

namespace WebCore {

PassRefPtr<TransformOperation> PerspectiveTransformOperation::blend(const TransformOperation* from, double progress, bool blendToIdentity)
{
    if (from && !from->isSameType(*this))
        return this;
    
    if (blendToIdentity) {
        double p = floatValueForLength(m_p, 1);
        p = WebCore::blend(p, 1.0, progress); // FIXME: this seems wrong. https://bugs.webkit.org/show_bug.cgi?id=52700
        return PerspectiveTransformOperation::create(Length(clampToPositiveInteger(p), Fixed));
    }
    
    const PerspectiveTransformOperation* fromOp = static_cast<const PerspectiveTransformOperation*>(from);
    Length fromP = fromOp ? fromOp->m_p : Length(m_p.type());
    Length toP = m_p;

    TransformationMatrix fromT;
    TransformationMatrix toT;
    fromT.applyPerspective(floatValueForLength(fromP, 1));
    toT.applyPerspective(floatValueForLength(toP, 1));
    toT.blend(fromT, progress);
    TransformationMatrix::DecomposedType decomp;
    toT.decompose(decomp);

    if (decomp.perspectiveZ) {
        double val = -1.0 / decomp.perspectiveZ;
        return PerspectiveTransformOperation::create(Length(clampToPositiveInteger(val), Fixed));
    }
    return PerspectiveTransformOperation::create(Length(0, Fixed));
}

} // namespace WebCore