path: root/Source/WebCore/platform/graphics/TextRun.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, 2011 Apple 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 TextRun_h
#define TextRun_h

#include "TextDirection.h"
#include <wtf/RefCounted.h>
#include <wtf/text/WTFString.h>

namespace WebCore {

class FloatPoint;
class FloatRect;
class Font;
class GraphicsContext;
class GlyphBuffer;
class SimpleFontData;
struct GlyphData;
struct WidthIterator;

class TextRun {
    WTF_MAKE_FAST_ALLOCATED;
public:
    enum ExpansionBehaviorFlags {
        ForbidTrailingExpansion = 0 << 0,
        AllowTrailingExpansion = 1 << 0,
        ForbidLeadingExpansion = 0 << 1,
        AllowLeadingExpansion = 1 << 1,
    };

    typedef unsigned ExpansionBehavior;

    enum RoundingHackFlags {
        NoRounding = 0,
        RunRounding = 1 << 0,
        WordRounding = 1 << 1,
    };

    typedef unsigned RoundingHacks;

#if PLATFORM(MAC)
    TextRun(const LChar* c, unsigned len, float xpos = 0, float expansion = 0, ExpansionBehavior expansionBehavior = AllowTrailingExpansion | ForbidLeadingExpansion, TextDirection direction = LTR, bool directionalOverride = false, bool characterScanForCodePath = true, RoundingHacks roundingHacks = RunRounding | WordRounding)
        : m_charactersLength(len)
        , m_len(len)
        , m_xpos(xpos)
#if ENABLE(SVG)
        , m_horizontalGlyphStretch(1)
#endif
        , m_expansion(expansion)
        , m_expansionBehavior(expansionBehavior)
        , m_is8Bit(true)
        , m_allowTabs(false)
        , m_direction(direction)
        , m_directionalOverride(directionalOverride)
        , m_characterScanForCodePath(characterScanForCodePath)
        , m_applyRunRounding((roundingHacks & RunRounding) && s_allowsRoundingHacks)
        , m_applyWordRounding((roundingHacks & WordRounding) && s_allowsRoundingHacks)
        , m_disableSpacing(false)
        , m_tabSize(0)
    {
        m_data.characters8 = c;
    }
#endif

    TextRun(const UChar* c, unsigned len, float xpos = 0, float expansion = 0, ExpansionBehavior expansionBehavior = AllowTrailingExpansion | ForbidLeadingExpansion, TextDirection direction = LTR, bool directionalOverride = false, bool characterScanForCodePath = true, RoundingHacks roundingHacks = RunRounding | WordRounding)
        : m_charactersLength(len)
        , m_len(len)
        , m_xpos(xpos)
#if ENABLE(SVG)
        , m_horizontalGlyphStretch(1)
#endif
        , m_expansion(expansion)
        , m_expansionBehavior(expansionBehavior)
        , m_is8Bit(false)
        , m_allowTabs(false)
        , m_direction(direction)
        , m_directionalOverride(directionalOverride)
        , m_characterScanForCodePath(characterScanForCodePath)
        , m_applyRunRounding((roundingHacks & RunRounding) && s_allowsRoundingHacks)
        , m_applyWordRounding((roundingHacks & WordRounding) && s_allowsRoundingHacks)
        , m_disableSpacing(false)
        , m_tabSize(0)
    {
        m_data.characters16 = c;
    }
    
    TextRun(const String& s, float xpos = 0, float expansion = 0, ExpansionBehavior expansionBehavior = AllowTrailingExpansion | ForbidLeadingExpansion, TextDirection direction = LTR, bool directionalOverride = false, bool characterScanForCodePath = true, RoundingHacks roundingHacks = RunRounding | WordRounding)
        : m_charactersLength(s.length())
        , m_len(s.length())
        , m_xpos(xpos)
#if ENABLE(SVG)
        , m_horizontalGlyphStretch(1)
#endif
        , m_expansion(expansion)
        , m_expansionBehavior(expansionBehavior)
        , m_allowTabs(false)
        , m_direction(direction)
        , m_directionalOverride(directionalOverride)
        , m_characterScanForCodePath(characterScanForCodePath)
        , m_applyRunRounding((roundingHacks & RunRounding) && s_allowsRoundingHacks)
        , m_applyWordRounding((roundingHacks & WordRounding) && s_allowsRoundingHacks)
        , m_disableSpacing(false)
        , m_tabSize(0)
    {
#if PLATFORM(MAC)
        if (m_charactersLength && s.is8Bit()) {
            m_data.characters16 = s.characters();
            m_is8Bit = false;
// FIXME: Change this to:
//          m_data.characters8 = s.characters8();
//          m_is8Bit = true;
// when other 8 bit rendering changes are landed.
        } else {
            m_data.characters16 = s.characters();
            m_is8Bit = false;
        }
#else
        m_data.characters16 = s.characters();
        m_is8Bit = false;
#endif
    }

    TextRun subRun(unsigned startOffset, unsigned length) const
    {
        ASSERT(startOffset < m_len);

        TextRun result = *this;

        if (is8Bit())
            result.setText(data8(startOffset), length);
        else
            result.setText(data16(startOffset), length);

        return result;
    }

    UChar operator[](unsigned i) const { ASSERT(i < m_len); return is8Bit() ? m_data.characters8[i] :m_data.characters16[i]; }
    const LChar* data8(unsigned i) const { ASSERT(i < m_len); ASSERT(is8Bit()); return &m_data.characters8[i]; }
    const UChar* data16(unsigned i) const { ASSERT(i < m_len); ASSERT(!is8Bit()); return &m_data.characters16[i]; }

    const LChar* characters8() const { ASSERT(is8Bit()); return m_data.characters8; }
    const UChar* characters16() const { ASSERT(!is8Bit()); return m_data.characters16; }
    
    bool is8Bit() const { return m_is8Bit; }
    int length() const { return m_len; }
    int charactersLength() const { return m_charactersLength; }

    void setText(const LChar* c, unsigned len) { m_data.characters8 = c; m_len = len; m_is8Bit = true;}
    void setText(const UChar* c, unsigned len) { m_data.characters16 = c; m_len = len; m_is8Bit = false;}
    void setCharactersLength(unsigned charactersLength) { m_charactersLength = charactersLength; }

#if ENABLE(SVG)
    float horizontalGlyphStretch() const { return m_horizontalGlyphStretch; }
    void setHorizontalGlyphStretch(float scale) { m_horizontalGlyphStretch = scale; }
#endif

    bool allowTabs() const { return m_allowTabs; }
    unsigned tabSize() const { return m_tabSize; }
    void setTabSize(bool, unsigned);

    float xPos() const { return m_xpos; }
    void setXPos(float xPos) { m_xpos = xPos; }
    float expansion() const { return m_expansion; }
    bool allowsLeadingExpansion() const { return m_expansionBehavior & AllowLeadingExpansion; }
    bool allowsTrailingExpansion() const { return m_expansionBehavior & AllowTrailingExpansion; }
    TextDirection direction() const { return static_cast<TextDirection>(m_direction); }
    bool rtl() const { return m_direction == RTL; }
    bool ltr() const { return m_direction == LTR; }
    bool directionalOverride() const { return m_directionalOverride; }
    bool characterScanForCodePath() const { return m_characterScanForCodePath; }
    bool applyRunRounding() const { return m_applyRunRounding; }
    bool applyWordRounding() const { return m_applyWordRounding; }
    bool spacingDisabled() const { return m_disableSpacing; }

    void disableSpacing() { m_disableSpacing = true; }
    void disableRoundingHacks() { m_applyRunRounding = m_applyWordRounding = false; }
    void setDirection(TextDirection direction) { m_direction = direction; }
    void setDirectionalOverride(bool override) { m_directionalOverride = override; }
    void setCharacterScanForCodePath(bool scan) { m_characterScanForCodePath = scan; }

    class RenderingContext : public RefCounted<RenderingContext> {
    public:
        virtual ~RenderingContext() { }

#if ENABLE(SVG_FONTS)
        virtual GlyphData glyphDataForCharacter(const Font&, const TextRun&, WidthIterator&, UChar32 character, bool mirror, int currentCharacter, unsigned& advanceLength) = 0;
        virtual void drawSVGGlyphs(GraphicsContext*, const TextRun&, const SimpleFontData*, const GlyphBuffer&, int from, int to, const FloatPoint&) const = 0;
        virtual float floatWidthUsingSVGFont(const Font&, const TextRun&, int& charsConsumed, String& glyphName) const = 0;
#endif
    };

    RenderingContext* renderingContext() const { return m_renderingContext.get(); }
    void setRenderingContext(PassRefPtr<RenderingContext> context) { m_renderingContext = context; }

    static void setAllowsRoundingHacks(bool);
    static bool allowsRoundingHacks();

private:
    static bool s_allowsRoundingHacks;

    union {
        const LChar* characters8;
        const UChar* characters16;
    } m_data;
    unsigned m_charactersLength; // Marks the end of the characters buffer. Default equals to m_len.
    unsigned m_len;

    // m_xpos is the x position relative to the left start of the text line, not relative to the left
    // start of the containing block. In the case of right alignment or center alignment, left start of
    // the text line is not the same as left start of the containing block.
    float m_xpos;  
#if ENABLE(SVG)
    float m_horizontalGlyphStretch;
#endif

    float m_expansion;
    ExpansionBehavior m_expansionBehavior : 2;
    unsigned m_is8Bit : 1;
    unsigned m_allowTabs : 1;
    unsigned m_direction : 1;
    unsigned m_directionalOverride : 1; // Was this direction set by an override character.
    unsigned m_characterScanForCodePath : 1;
    unsigned m_applyRunRounding : 1;
    unsigned m_applyWordRounding : 1;
    unsigned m_disableSpacing : 1;
    unsigned m_tabSize;
    RefPtr<RenderingContext> m_renderingContext;
};

inline void TextRun::setTabSize(bool allow, unsigned size)
{
    m_allowTabs = allow;
    m_tabSize = size;
}

}

#endif