flutter_flutter/engine/platform/fonts/Font.h

/*
 * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
 *           (C) 2000 Antti Koivisto (koivisto@kde.org)
 *           (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2003, 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Holger Hans Peter Freyther
 *
 * 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_FONT_H_
#define SKY_ENGINE_PLATFORM_FONTS_FONT_H_

#include "sky/engine/platform/PlatformExport.h"
#include "sky/engine/platform/fonts/FontDescription.h"
#include "sky/engine/platform/fonts/FontFallbackList.h"
#include "sky/engine/platform/fonts/SimpleFontData.h"
#include "sky/engine/platform/fonts/TextBlob.h"
#include "sky/engine/platform/text/TextDirection.h"
#include "sky/engine/platform/text/TextPath.h"
#include "sky/engine/wtf/HashMap.h"
#include "sky/engine/wtf/HashSet.h"
#include "sky/engine/wtf/MathExtras.h"
#include "sky/engine/wtf/unicode/CharacterNames.h"

// "X11/X.h" defines Complex to 0 and conflicts
// with Complex value in CodePath enum.
#ifdef Complex
#undef Complex
#endif

class SkTextBlob;
struct SkPoint;

namespace blink {

class FloatPoint;
class FloatRect;
class FontData;
class FontMetrics;
class FontSelector;
class GlyphBuffer;
class GraphicsContext;
class TextRun;
struct TextRunPaintInfo;

struct GlyphData;

struct GlyphOverflow {
    GlyphOverflow()
        : left(0)
        , right(0)
        , top(0)
        , bottom(0)
        , computeBounds(false)
    {
    }

    bool isZero() const
    {
        return !left && !right && !top && !bottom;
    }

    int left;
    int right;
    int top;
    int bottom;
    bool computeBounds;
};


class PLATFORM_EXPORT Font {
public:
    Font();
    Font(const FontDescription&);
    ~Font();

    Font(const Font&);
    Font& operator=(const Font&);

    bool operator==(const Font& other) const;
    bool operator!=(const Font& other) const { return !(*this == other); }

    const FontDescription& fontDescription() const { return m_fontDescription; }

    void update(PassRefPtr<FontSelector>) const;

    enum CustomFontNotReadyAction { DoNotPaintIfFontNotReady, UseFallbackIfFontNotReady };
    void drawText(GraphicsContext*, const TextRunPaintInfo&, const FloatPoint&) const;
    float drawUncachedText(GraphicsContext*, const TextRunPaintInfo&, const FloatPoint&, CustomFontNotReadyAction) const;
    void drawEmphasisMarks(GraphicsContext*, const TextRunPaintInfo&, const AtomicString& mark, const FloatPoint&) const;

    float width(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
    float width(const TextRun&, int& charsConsumed, Glyph& glyphId) const;

    int offsetForPosition(const TextRun&, float position, bool includePartialGlyphs) const;
    FloatRect selectionRectForText(const TextRun&, const FloatPoint&, int h, int from = 0, int to = -1, bool accountForGlyphBounds = false) const;

    bool isFixedPitch() const;

    // Metrics that we query the FontFallbackList for.
    const FontMetrics& fontMetrics() const { return primaryFont()->fontMetrics(); }
    float spaceWidth() const { return primaryFont()->spaceWidth() + fontDescription().letterSpacing(); }
    float tabWidth(const SimpleFontData&, unsigned tabSize, float position) const;
    float tabWidth(unsigned tabSize, float position) const { return tabWidth(*primaryFont(), tabSize, position); }

    int emphasisMarkAscent(const AtomicString&) const;
    int emphasisMarkDescent(const AtomicString&) const;
    int emphasisMarkHeight(const AtomicString&) const;

    const SimpleFontData* primaryFont() const;
    const FontData* fontDataAt(unsigned) const;
    inline GlyphData glyphDataForCharacter(UChar32 c, bool mirror, FontDataVariant variant = AutoVariant) const
    {
        return glyphDataAndPageForCharacter(c, mirror, variant).first;
    }
    std::pair<GlyphData, GlyphPage*> glyphDataAndPageForCharacter(UChar32, bool mirror, FontDataVariant = AutoVariant) const;
    bool primaryFontHasGlyphForCharacter(UChar32) const;

    CodePath codePath(const TextRun&) const;

private:
    enum ForTextEmphasisOrNot { NotForTextEmphasis, ForTextEmphasis };

    // Returns the initial in-stream advance.
    float buildGlyphBuffer(const TextRunPaintInfo&, GlyphBuffer&, ForTextEmphasisOrNot = NotForTextEmphasis) const;
    PassTextBlobPtr buildTextBlob(const GlyphBuffer&, float initialAdvance, const FloatRect& bounds) const;
    void drawGlyphs(GraphicsContext*, const SimpleFontData*, const GlyphBuffer&, unsigned from, unsigned numGlyphs, const FloatPoint&, const FloatRect& textRect) const;
    void drawTextBlob(GraphicsContext*, const SkTextBlob*, const SkPoint& origin) const;
    float drawGlyphBuffer(GraphicsContext*, const TextRunPaintInfo&, const GlyphBuffer&, const FloatPoint&) const;
    void drawEmphasisMarks(GraphicsContext*, const TextRunPaintInfo&, const GlyphBuffer&, const AtomicString&, const FloatPoint&) const;
    float floatWidthForSimpleText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, IntRectExtent* glyphBounds = 0) const;
    int offsetForPositionForSimpleText(const TextRun&, float position, bool includePartialGlyphs) const;
    FloatRect selectionRectForSimpleText(const TextRun&, const FloatPoint&, int h, int from, int to, bool accountForGlyphBounds) const;

    bool getEmphasisMarkGlyphData(const AtomicString&, GlyphData&) const;

    float floatWidthForComplexText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts, IntRectExtent* glyphBounds) const;
    int offsetForPositionForComplexText(const TextRun&, float position, bool includePartialGlyphs) const;
    FloatRect selectionRectForComplexText(const TextRun&, const FloatPoint&, int h, int from, int to) const;

    friend struct WidthIterator;

public:
    // Useful for debugging the different font rendering code paths.
    static void setCodePath(CodePath);
    static CodePath codePath();
    static CodePath s_codePath;

    FontSelector* fontSelector() const;

    FontFallbackList* fontList() const { return m_fontFallbackList.get(); }

    void willUseFontData(UChar32) const;

    static FloatRect pixelSnappedSelectionRect(float fromX, float toX, float y, float height);
private:
    bool loadingCustomFonts() const
    {
        return m_fontFallbackList && m_fontFallbackList->loadingCustomFonts();
    }

    bool shouldSkipDrawing() const
    {
        return m_fontFallbackList && m_fontFallbackList->shouldSkipDrawing();
    }

    FontDescription m_fontDescription;
    mutable RefPtr<FontFallbackList> m_fontFallbackList;
};

inline Font::~Font()
{
}

inline const SimpleFontData* Font::primaryFont() const
{
    ASSERT(m_fontFallbackList);
    return m_fontFallbackList->primarySimpleFontData(m_fontDescription);
}

inline const FontData* Font::fontDataAt(unsigned index) const
{
    ASSERT(m_fontFallbackList);
    return m_fontFallbackList->fontDataAt(m_fontDescription, index);
}

inline bool Font::isFixedPitch() const
{
    ASSERT(m_fontFallbackList);
    return m_fontFallbackList->isFixedPitch(m_fontDescription);
}

inline FontSelector* Font::fontSelector() const
{
    return m_fontFallbackList ? m_fontFallbackList->fontSelector() : 0;
}

inline float Font::tabWidth(const SimpleFontData& fontData, unsigned tabSize, float position) const
{
    if (!tabSize)
        return fontDescription().letterSpacing();
    float tabWidth = tabSize * fontData.spaceWidth() + fontDescription().letterSpacing();
    return tabWidth - fmodf(position, tabWidth);
}

} // namespace blink

#endif  // SKY_ENGINE_PLATFORM_FONTS_FONT_H_