Source/WebCore/rendering/mathml/MathMLStyle.cpp

/*
 * Copyright (C) 2016 Igalia S.L. All rights reserved.
 *
 * 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
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 * 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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#include "config.h"
#include "MathMLStyle.h"

#if ENABLE(MATHML)

#include "MathMLElement.h"
#include "MathMLNames.h"
#include "RenderMathMLBlock.h"
#include "RenderMathMLFraction.h"
#include "RenderMathMLMath.h"
#include "RenderMathMLRoot.h"
#include "RenderMathMLScripts.h"
#include "RenderMathMLToken.h"
#include "RenderMathMLUnderOver.h"

namespace WebCore {

using namespace MathMLNames;

Ref<MathMLStyle> MathMLStyle::create()
{
    return adoptRef(*new MathMLStyle());
}

const MathMLStyle* MathMLStyle::getMathMLStyle(RenderObject* renderer)
{
    // FIXME: Should we make RenderMathMLTable derive from RenderMathMLBlock in order to simplify this?
    if (is<RenderMathMLTable>(renderer))
        return &downcast<RenderMathMLTable>(*renderer).mathMLStyle();
    if (is<RenderMathMLBlock>(renderer))
        return &downcast<RenderMathMLBlock>(*renderer).mathMLStyle();
    return nullptr;
}

void MathMLStyle::resolveMathMLStyleTree(RenderObject* renderer)
{
    for (auto* child = renderer; child; child = child->nextInPreOrder(renderer)) {
        // FIXME: Should we make RenderMathMLTable derive from RenderMathMLBlock in order to simplify this?
        if (is<RenderMathMLTable>(child))
            downcast<RenderMathMLTable>(*child).mathMLStyle().resolveMathMLStyle(child);
        else if (is<RenderMathMLBlock>(child))
            downcast<RenderMathMLBlock>(*child).mathMLStyle().resolveMathMLStyle(child);
    }
}

RenderObject* MathMLStyle::getMathMLParentNode(RenderObject* renderer)
{
    auto* parentRenderer = renderer->parent();

    while (parentRenderer && !(is<RenderMathMLTable>(parentRenderer) || is<RenderMathMLBlock>(parentRenderer)))
        parentRenderer = parentRenderer->parent();

    return parentRenderer;
}

void MathMLStyle::updateStyleIfNeeded(RenderObject* renderer, bool oldDisplayStyle, MathMLElement::MathVariant oldMathVariant)
{
    // RenderMathMLFencedOperator does not support mathvariant or displaystyle transforms.
    // See https://bugs.webkit.org/show_bug.cgi?id=160509#c1.
    bool isNonAnonymousTokenElement = is<RenderMathMLToken>(renderer) && !renderer->isAnonymous();

    if (oldDisplayStyle != m_displayStyle) {
        renderer->setNeedsLayoutAndPrefWidthsRecalc();
        if (isNonAnonymousTokenElement)
            downcast<RenderMathMLToken>(renderer)->updateTokenContent();
        else if (is<RenderMathMLFraction>(renderer))
            downcast<RenderMathMLFraction>(renderer)->updateFromElement();
    }
    if (oldMathVariant != m_mathVariant) {
        if (isNonAnonymousTokenElement)
            downcast<RenderMathMLToken>(renderer)->updateTokenContent();
    }
}

void MathMLStyle::resolveMathMLStyle(RenderObject* renderer)
{
    ASSERT(renderer);

    bool oldDisplayStyle = m_displayStyle;
    MathMLElement::MathVariant oldMathVariant = m_mathVariant;
    auto* parentRenderer = getMathMLParentNode(renderer);
    const MathMLStyle* parentStyle = getMathMLStyle(parentRenderer);

    // By default, we just inherit the style from our parent.
    m_displayStyle = false;
    m_mathVariant = MathMLElement::MathVariant::None;
    if (parentStyle) {
        setDisplayStyle(parentStyle->displayStyle());
        setMathVariant(parentStyle->mathVariant());
    }

    // Early return for anonymous renderers.
    if (renderer->isAnonymous()) {
        updateStyleIfNeeded(renderer, oldDisplayStyle, oldMathVariant);
        return;
    }

    if (is<RenderMathMLMath>(renderer) || is<RenderMathMLTable>(renderer))
        m_displayStyle = false; // The default displaystyle of <math> and <mtable> is false.
    else if (parentRenderer) {
        if (is<RenderMathMLFraction>(parentRenderer))
            m_displayStyle = false; // <mfrac> sets displaystyle to false within its numerator and denominator.
        else if ((is<RenderMathMLRoot>(parentRenderer) && !parentRenderer->isRenderMathMLSquareRoot()) || is<RenderMathMLScripts>(parentRenderer) || is<RenderMathMLUnderOver>(parentRenderer)) {
            // <mroot>, <msub>, <msup>, <msubsup>, <mmultiscripts>, <munder>, <mover> and <munderover> elements set displaystyle to false within their scripts.
            auto* base = downcast<RenderBox>(parentRenderer)->firstChildBox();
            if (renderer != base)
                m_displayStyle = false;
        }
    }

    // The displaystyle and mathvariant attributes override the default behavior.
    auto* element = downcast<RenderElement>(renderer)->element();
    if (is<MathMLElement>(element)) {
        Optional<bool> displayStyle = downcast<MathMLElement>(element)->specifiedDisplayStyle();
        if (displayStyle)
            m_displayStyle = displayStyle.value();
        Optional<MathMLElement::MathVariant> mathVariant = downcast<MathMLElement>(element)->specifiedMathVariant();
        if (mathVariant)
            m_mathVariant = mathVariant.value();
    }
    updateStyleIfNeeded(renderer, oldDisplayStyle, oldMathVariant);
}

}

#endif // ENABLE(MATHML)