Source/WebCore/platform/graphics/GlyphPage.h

/*
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 * Copyright (C) Research In Motion Limited 2011. All rights reserved.
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 *     notice, this list of conditions and the following disclaimer. 
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 *     from this software without specific prior written permission. 
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#ifndef GlyphPage_h
#define GlyphPage_h

#include "Glyph.h"
#include <unicode/utypes.h>
#include <wtf/RefCounted.h>
#include <wtf/Ref.h>

namespace WebCore {

class Font;

// Holds the glyph index and the corresponding Font information for a given
// character.
struct GlyphData {
    GlyphData(Glyph glyph = 0, const Font* font = nullptr)
        : glyph(glyph)
        , font(font)
    {
    }

    bool isValid() const { return glyph || font; }

    Glyph glyph;
    const Font* font;
};

// A GlyphPage contains a fixed-size set of GlyphData mappings for a contiguous
// range of characters in the Unicode code space. GlyphPages are indexed
// starting from 0 and incrementing for each "size" number of glyphs.
class GlyphPage : public RefCounted<GlyphPage> {
public:
    static Ref<GlyphPage> create(const Font& font)
    {
        return adoptRef(*new GlyphPage(font));
    }

    ~GlyphPage()
    {
        --s_count;
    }

    static unsigned count() { return s_count; }

    static const unsigned size = 16;

    static unsigned sizeForPageNumber(unsigned) { return 16; }
    static unsigned indexForCodePoint(UChar32 c) { return c % size; }
    static unsigned pageNumberForCodePoint(UChar32 c) { return c / size; }
    static UChar32 startingCodePointInPageNumber(unsigned pageNumber) { return pageNumber * size; }
    static bool pageNumberIsUsedForArabic(unsigned pageNumber) { return startingCodePointInPageNumber(pageNumber) >= 0x600 && startingCodePointInPageNumber(pageNumber) + sizeForPageNumber(pageNumber) < 0x700; }

    GlyphData glyphDataForCharacter(UChar32 c) const
    {
        return glyphDataForIndex(indexForCodePoint(c));
    }

    Glyph glyphForCharacter(UChar32 c) const
    {
        return glyphForIndex(indexForCodePoint(c));
    }

    GlyphData glyphDataForIndex(unsigned index) const
    {
        Glyph glyph = glyphForIndex(index);
        return GlyphData(glyph, glyph ? &m_font : nullptr);
    }

    Glyph glyphForIndex(unsigned index) const
    {
        ASSERT_WITH_SECURITY_IMPLICATION(index < size);
        return m_glyphs[index];
    }

    // FIXME: Pages are immutable after initialization. This should be private.
    void setGlyphForIndex(unsigned index, Glyph glyph)
    {
        ASSERT_WITH_SECURITY_IMPLICATION(index < size);
        m_glyphs[index] = glyph;
    }

    const Font& font() const
    {
        return m_font;
    }

    // Implemented by the platform.
    bool fill(UChar* characterBuffer, unsigned bufferLength);

private:
    explicit GlyphPage(const Font& font)
        : m_font(font)
    {
        ++s_count;
    }

    const Font& m_font;
    Glyph m_glyphs[size] { };

    WEBCORE_EXPORT static unsigned s_count;
};

} // namespace WebCore

#endif // GlyphPage_h