RenderMathMLBlock.h   [plain text]

/*
 * Copyright (C) 2010 Alex Milowski (alex@milowski.com). All rights reserved.
 * Copyright (C) 2012 David Barton (dbarton@mathscribe.com). 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
 *    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 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,
 * DATA, OR 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

#if ENABLE(MATHML)

#include "MathMLElement.h"
#include "MathMLStyle.h"
#include "RenderBlock.h"
#include "RenderTable.h"
#include "StyleInheritedData.h"

#define ENABLE_DEBUG_MATH_LAYOUT 0

namespace WebCore {

class RenderMathMLOperator;

class RenderMathMLBlock : public RenderBlock {
public:
    RenderMathMLBlock(Element&, RenderStyle&&);
    RenderMathMLBlock(Document&, RenderStyle&&);
    virtual ~RenderMathMLBlock();

    MathMLStyle* mathMLStyle() const { return const_cast<MathMLStyle*>(&m_mathMLStyle.get()); }

    bool isChildAllowed(const RenderObject&, const RenderStyle&) const override;

    // MathML defines an "embellished operator" as roughly an <mo> that may have subscripts,
    // superscripts, underscripts, overscripts, or a denominator (as in d/dx, where "d" is some
    // differential operator). The padding, precedence, and stretchiness of the base <mo> should
    // apply to the embellished operator as a whole. unembellishedOperator() checks for being an
    // embellished operator, and omits any embellishments.
    // FIXME: We don't yet handle all the cases in the MathML spec. See
    // https://bugs.webkit.org/show_bug.cgi?id=78617.
    virtual RenderMathMLOperator* unembellishedOperator() { return 0; }

    int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const override;

#if ENABLE(DEBUG_MATH_LAYOUT)
    virtual void paint(PaintInfo&, const LayoutPoint&);
#endif

protected:
    LayoutUnit ruleThicknessFallback() const
    {
        // This function returns a value for the default rule thickness (TeX's \xi_8) to be used as a fallback when we lack a MATH table.
        // This arbitrary value of 0.05em was used in early WebKit MathML implementations for the thickness of the fraction bars.
        // Note that Gecko has a slower but more accurate version that measures the thickness of U+00AF MACRON to be more accurate and otherwise fallback to some arbitrary value.
        return 0.05f * style().fontCascade().size();
    }

    LayoutUnit mathAxisHeight() const;
    LayoutUnit mirrorIfNeeded(LayoutUnit horizontalOffset, LayoutUnit boxWidth = 0) const;
    LayoutUnit mirrorIfNeeded(LayoutUnit horizontalOffset, const RenderBox& child) const { return mirrorIfNeeded(horizontalOffset, child.logicalWidth()); }

    static LayoutUnit ascentForChild(const RenderBox& child)
    {
        return child.firstLineBaseline().valueOr(child.logicalHeight());
    }

    void layoutBlock(bool relayoutChildren, LayoutUnit pageLogicalHeight = 0) override;

private:
    bool isRenderMathMLBlock() const final { return true; }
    const char* renderName() const override { return "RenderMathMLBlock"; }
    bool avoidsFloats() const final { return true; }
    bool canDropAnonymousBlockChild() const final { return false; }
    void layoutItems(bool relayoutChildren);

    Ref<MathMLStyle> m_mathMLStyle;
};

class RenderMathMLTable final : public RenderTable {
public:
    explicit RenderMathMLTable(Element& element, RenderStyle&& style)
        : RenderTable(element, WTFMove(style))
        , m_mathMLStyle(MathMLStyle::create())
    {
    }


    MathMLStyle* mathMLStyle() const { return const_cast<MathMLStyle*>(&m_mathMLStyle.get()); }

private:
    bool isRenderMathMLTable() const final { return true; }
    const char* renderName() const final { return "RenderMathMLTable"; }
    Optional<int> firstLineBaseline() const final;

    Ref<MathMLStyle> m_mathMLStyle;
};

// Parsing functions for MathML Length values
bool parseMathMLLength(const String&, LayoutUnit&, const RenderStyle*, bool allowNegative = true);
LayoutUnit toUserUnits(const MathMLElement::Length&, const RenderStyle&, const LayoutUnit& referenceValue);

} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderMathMLBlock, isRenderMathMLBlock())
SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderMathMLTable, isRenderMathMLTable())

#endif // ENABLE(MATHML)