sky/engine/platform/fonts/WidthIterator.h

/*
 * Copyright (C) 2003, 2006, 2008, 2011 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Holger Hans Peter Freyther
 * Copyright (C) 2014 Google Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef SKY_ENGINE_PLATFORM_FONTS_WIDTHITERATOR_H_
#define SKY_ENGINE_PLATFORM_FONTS_WIDTHITERATOR_H_

#include "sky/engine/platform/PlatformExport.h"
#include "sky/engine/platform/text/TextRun.h"
#include "sky/engine/wtf/HashSet.h"
#include "sky/engine/wtf/Vector.h"
#include "sky/engine/wtf/unicode/Unicode.h"

namespace blink {

class Font;
class GlyphBuffer;
class SimpleFontData;
class TextRun;
struct GlyphData;

struct PLATFORM_EXPORT WidthIterator {
    WTF_MAKE_FAST_ALLOCATED;
public:
    WidthIterator(const Font*, const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, bool accountForGlyphBounds = false, bool forTextEmphasis = false);

    unsigned advance(int to, GlyphBuffer* = 0);
    bool advanceOneCharacter(float& width);

    float maxGlyphBoundingBoxY() const { ASSERT(m_accountForGlyphBounds); return m_maxGlyphBoundingBoxY; }
    float minGlyphBoundingBoxY() const { ASSERT(m_accountForGlyphBounds); return m_minGlyphBoundingBoxY; }
    float firstGlyphOverflow() const { ASSERT(m_accountForGlyphBounds); return m_firstGlyphOverflow; }
    float lastGlyphOverflow() const { ASSERT(m_accountForGlyphBounds); return m_lastGlyphOverflow; }

    const TextRun& run() const { return m_run; }
    float runWidthSoFar() const { return m_runWidthSoFar; }

    const Font* m_font;

    const TextRun& m_run;

    unsigned m_currentCharacter;
    float m_runWidthSoFar;
    float m_expansion;
    float m_expansionPerOpportunity;
    bool m_isAfterExpansion;

private:
    struct CharacterData {
        UChar32 character;
        unsigned clusterLength;
        int characterOffset;
    };

    GlyphData glyphDataForCharacter(CharacterData&);
    float characterWidth(UChar32, const GlyphData&) const;
    void cacheFallbackFont(UChar32, const SimpleFontData*, const SimpleFontData* primaryFont);
    float adjustSpacing(float, const CharacterData&, const SimpleFontData&, GlyphBuffer*);
    void updateGlyphBounds(const GlyphData&, float width, bool firstCharacter);

    template <typename TextIterator>
    unsigned advanceInternal(TextIterator&, GlyphBuffer*);

    HashSet<const SimpleFontData*>* m_fallbackFonts;
    float m_maxGlyphBoundingBoxY;
    float m_minGlyphBoundingBoxY;
    float m_firstGlyphOverflow;
    float m_lastGlyphOverflow;

    bool m_accountForGlyphBounds : 1;
    bool m_forTextEmphasis : 1;
};

} // namespace blink

#endif  // SKY_ENGINE_PLATFORM_FONTS_WIDTHITERATOR_H_