ftxgpos.h   [plain text]

/*******************************************************************
 *
 *  ftxgpos.h
 *
 *    TrueType Open GPOS table support
 *
 *  Copyright 1996-1999 by
 *  David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 *  This file is part of the FreeType project, and may only be used
 *  modified and distributed under the terms of the FreeType project
 *  license, LICENSE.TXT.  By continuing to use, modify, or distribute
 *  this file you indicate that you have read the license and
 *  understand and accept it fully.
 *
 ******************************************************************/

#ifndef FTXOPEN_H
#error "Don't include this file! Use ftxopen.h instead."
#endif

#ifndef FTXGPOS_H
#define FTXGPOS_H

#ifdef __cplusplus
extern "C" {
#endif

#define TTO_Err_Invalid_GPOS_SubTable_Format  0x1020
#define TTO_Err_Invalid_GPOS_SubTable         0x1021


/* Lookup types for glyph positioning */

#define GPOS_LOOKUP_SINGLE    1
#define GPOS_LOOKUP_PAIR      2
#define GPOS_LOOKUP_CURSIVE   3
#define GPOS_LOOKUP_MARKBASE  4
#define GPOS_LOOKUP_MARKLIG   5
#define GPOS_LOOKUP_MARKMARK  6
#define GPOS_LOOKUP_CONTEXT   7
#define GPOS_LOOKUP_CHAIN     8


  struct  TTO_GPOSHeader_
  {
    TT_Bool          loaded;
    TT_ULong         offset;

    TT_Fixed         Version;

    TTO_ScriptList   ScriptList;
    TTO_FeatureList  FeatureList;
    TTO_LookupList   LookupList;

    TTO_GDEFHeader*  gdef;
  };

  typedef struct TTO_GPOSHeader_  TTO_GPOSHeader;


  /* shared tables */

  struct  TTO_ValueRecord_
  {
    TT_Short    XPlacement;             /* horizontal adjustment for
                                           placement                      */
    TT_Short    YPlacement;             /* vertical adjustment for
                                           placement                      */
    TT_Short    XAdvance;               /* horizontal adjustment for
                                           advance                        */
    TT_Short    YAdvance;               /* vertical adjustment for
                                           advance                        */
    TTO_Device  XPlacementDevice;       /* device table for horizontal
                                           placement                      */
    TTO_Device  YPlacementDevice;       /* device table for vertical
                                           placement                      */
    TTO_Device  XAdvanceDevice;         /* device table for horizontal
                                           advance                        */
    TTO_Device  YAdvanceDevice;         /* device table for vertical
                                           advance                        */
    TT_UShort   XIdPlacement;           /* horizontal placement metric ID */
    TT_UShort   YIdPlacement;           /* vertical placement metric ID   */
    TT_UShort   XIdAdvance;             /* horizontal advance metric ID   */
    TT_UShort   YIdAdvance;             /* vertical advance metric ID     */
  };

  typedef struct TTO_ValueRecord_  TTO_ValueRecord;


/* Mask values to scan the value format of the ValueRecord structure.
   We always expand compressed ValueRecords of the font.              */

#define HAVE_X_PLACEMENT         0x0001
#define HAVE_Y_PLACEMENT         0x0002
#define HAVE_X_ADVANCE           0x0004
#define HAVE_Y_ADVANCE           0x0008
#define HAVE_X_PLACEMENT_DEVICE  0x0010
#define HAVE_Y_PLACEMENT_DEVICE  0x0020
#define HAVE_X_ADVANCE_DEVICE    0x0040
#define HAVE_Y_ADVANCE_DEVICE    0x0080
#define HAVE_X_ID_PLACEMENT      0x0100
#define HAVE_Y_ID_PLACEMENT      0x0200
#define HAVE_X_ID_ADVANCE        0x0400
#define HAVE_Y_ID_ADVANCE        0x0800


  struct  TTO_AnchorFormat1_
  {
    TT_Short   XCoordinate;             /* horizontal value */
    TT_Short   YCoordinate;             /* vertical value   */
  };

  typedef struct TTO_AnchorFormat1_  TTO_AnchorFormat1;


  struct  TTO_AnchorFormat2_
  {
    TT_Short   XCoordinate;             /* horizontal value             */
    TT_Short   YCoordinate;             /* vertical value               */
    TT_UShort  AnchorPoint;             /* index to glyph contour point */
  };

  typedef struct TTO_AnchorFormat2_  TTO_AnchorFormat2;


  struct  TTO_AnchorFormat3_
  {
    TT_Short    XCoordinate;            /* horizontal value              */
    TT_Short    YCoordinate;            /* vertical value                */
    TTO_Device  XDeviceTable;           /* device table for X coordinate */
    TTO_Device  YDeviceTable;           /* device table for Y coordinate */
  };

  typedef struct TTO_AnchorFormat3_  TTO_AnchorFormat3;


  struct  TTO_AnchorFormat4_
  {
    TT_UShort  XIdAnchor;               /* horizontal metric ID */
    TT_UShort  YIdAnchor;               /* vertical metric ID   */
  };

  typedef struct TTO_AnchorFormat4_  TTO_AnchorFormat4;


  struct  TTO_Anchor_
  {
    TT_UShort  PosFormat;               /* 1, 2, 3, or 4 -- 0 indicates
                                           that there is no Anchor table */

    union
    {
      TTO_AnchorFormat1  af1;
      TTO_AnchorFormat2  af2;
      TTO_AnchorFormat3  af3;
      TTO_AnchorFormat4  af4;
    } af;
  };

  typedef struct TTO_Anchor_  TTO_Anchor;


  struct  TTO_MarkRecord_
  {
    TT_UShort   Class;                  /* mark class   */
    TTO_Anchor  MarkAnchor;             /* anchor table */
  };

  typedef struct TTO_MarkRecord_  TTO_MarkRecord;


  struct  TTO_MarkArray_
  {
    TT_UShort        MarkCount;         /* number of MarkRecord tables */
    TTO_MarkRecord*  MarkRecord;        /* array of MarkRecord tables  */
  };

  typedef struct TTO_MarkArray_  TTO_MarkArray;


  /* LookupType 1 */

  struct  TTO_SinglePosFormat1_
  {
    TTO_ValueRecord  Value;             /* ValueRecord for all covered
                                           glyphs                      */
  };

  typedef struct TTO_SinglePosFormat1_  TTO_SinglePosFormat1;


  struct  TTO_SinglePosFormat2_
  {
    TT_UShort         ValueCount;       /* number of ValueRecord tables */
    TTO_ValueRecord*  Value;            /* array of ValueRecord tables  */
  };

  typedef struct TTO_SinglePosFormat2_  TTO_SinglePosFormat2;


  struct  TTO_SinglePos_
  {
    TT_UShort     PosFormat;            /* 1 or 2         */
    TTO_Coverage  Coverage;             /* Coverage table */

    TT_UShort     ValueFormat;          /* format of ValueRecord table */

    union
    {
      TTO_SinglePosFormat1  spf1;
      TTO_SinglePosFormat2  spf2;
    } spf;
  };

  typedef struct TTO_SinglePos_  TTO_SinglePos;


  /* LookupType 2 */

  struct  TTO_PairValueRecord_
  {
    TT_UShort        SecondGlyph;       /* glyph ID for second glyph  */
    TTO_ValueRecord  Value1;            /* pos. data for first glyph  */
    TTO_ValueRecord  Value2;            /* pos. data for second glyph */
  };

  typedef struct TTO_PairValueRecord_  TTO_PairValueRecord;


  struct  TTO_PairSet_
  {
    TT_UShort             PairValueCount;
                                        /* number of PairValueRecord tables */
    TTO_PairValueRecord*  PairValueRecord;
                                        /* array of PairValueRecord tables  */
  };

  typedef struct TTO_PairSet_  TTO_PairSet;


  struct  TTO_PairPosFormat1_
  {
    TT_UShort     PairSetCount;         /* number of PairSet tables    */
    TTO_PairSet*  PairSet;              /* array of PairSet tables     */
  };

  typedef struct TTO_PairPosFormat1_  TTO_PairPosFormat1;


  struct  TTO_Class2Record_
  {
    TTO_ValueRecord  Value1;            /* pos. data for first glyph  */
    TTO_ValueRecord  Value2;            /* pos. data for second glyph */
  };

  typedef struct TTO_Class2Record_  TTO_Class2Record;


  struct  TTO_Class1Record_
  {
    TTO_Class2Record*  Class2Record;    /* array of Class2Record tables */
  };

  typedef struct TTO_Class1Record_  TTO_Class1Record;


  struct TTO_PairPosFormat2_
  {
    TTO_ClassDefinition  ClassDef1;     /* class def. for first glyph     */
    TTO_ClassDefinition  ClassDef2;     /* class def. for second glyph    */
    TT_UShort            Class1Count;   /* number of classes in ClassDef1
                                           table                          */
    TT_UShort            Class2Count;   /* number of classes in ClassDef2
                                           table                          */
    TTO_Class1Record*    Class1Record;  /* array of Class1Record tables   */
  };

  typedef struct TTO_PairPosFormat2_  TTO_PairPosFormat2;


  struct  TTO_PairPos_
  {
    TT_UShort     PosFormat;            /* 1 or 2         */
    TTO_Coverage  Coverage;             /* Coverage table */
    TT_UShort     ValueFormat1;         /* format of ValueRecord table
                                           for first glyph             */
    TT_UShort     ValueFormat2;         /* format of ValueRecord table
                                           for second glyph            */

    union
    {
      TTO_PairPosFormat1  ppf1;
      TTO_PairPosFormat2  ppf2;
    } ppf;
  };

  typedef struct TTO_PairPos_  TTO_PairPos;


  /* LookupType 3 */

  struct TTO_EntryExitRecord_
  {
    TTO_Anchor  EntryAnchor;            /* entry Anchor table */
    TTO_Anchor  ExitAnchor;             /* exit Anchor table  */
  };


  typedef struct TTO_EntryExitRecord_  TTO_EntryExitRecord;

  struct  TTO_CursivePos_
  {
    TT_UShort             PosFormat;    /* always 1                         */
    TTO_Coverage          Coverage;     /* Coverage table                   */
    TT_UShort             EntryExitCount;
                                        /* number of EntryExitRecord tables */
    TTO_EntryExitRecord*  EntryExitRecord;
                                        /* array of EntryExitRecord tables  */
  };

  typedef struct TTO_CursivePos_  TTO_CursivePos;


  /* LookupType 4 */

  struct  TTO_BaseRecord_
  {
    TTO_Anchor*  BaseAnchor;            /* array of base glyph anchor
                                           tables                     */
  };

  typedef struct TTO_BaseRecord_  TTO_BaseRecord;


  struct  TTO_BaseArray_
  {
    TT_UShort        BaseCount;         /* number of BaseRecord tables */
    TTO_BaseRecord*  BaseRecord;        /* array of BaseRecord tables  */
  };

  typedef struct TTO_BaseArray_  TTO_BaseArray;


  struct  TTO_MarkBasePos_
  {
    TT_UShort      PosFormat;           /* always 1                  */
    TTO_Coverage   MarkCoverage;        /* mark glyph coverage table */
    TTO_Coverage   BaseCoverage;        /* base glyph coverage table */
    TT_UShort      ClassCount;          /* number of mark classes    */
    TTO_MarkArray  MarkArray;           /* mark array table          */
    TTO_BaseArray  BaseArray;           /* base array table          */
  };

  typedef struct TTO_MarkBasePos_  TTO_MarkBasePos;


  /* LookupType 5 */

  struct  TTO_ComponentRecord_
  {
    TTO_Anchor*  LigatureAnchor;        /* array of ligature glyph anchor
                                           tables                         */
  };

  typedef struct TTO_ComponentRecord_  TTO_ComponentRecord;


  struct  TTO_LigatureAttach_
  {
    TT_UShort             ComponentCount;
                                        /* number of ComponentRecord tables */
    TTO_ComponentRecord*  ComponentRecord;
                                        /* array of ComponentRecord tables  */
  };

  typedef struct TTO_LigatureAttach_  TTO_LigatureAttach;


  struct  TTO_LigatureArray_
  {
    TT_UShort            LigatureCount; /* number of LigatureAttach tables */
    TTO_LigatureAttach*  LigatureAttach;
                                        /* array of LigatureAttach tables  */
  };

  typedef struct TTO_LigatureArray_  TTO_LigatureArray;


  struct  TTO_MarkLigPos_
  {
    TT_UShort          PosFormat;       /* always 1                      */
    TTO_Coverage       MarkCoverage;    /* mark glyph coverage table     */
    TTO_Coverage       LigatureCoverage;
                                        /* ligature glyph coverage table */
    TT_UShort          ClassCount;      /* number of mark classes        */
    TTO_MarkArray      MarkArray;       /* mark array table              */
    TTO_LigatureArray  LigatureArray;   /* ligature array table          */
  };

  typedef struct TTO_MarkLigPos_  TTO_MarkLigPos;


  /* LookupType 6 */

  struct TTO_Mark2Record_
  {
    TTO_Anchor*  Mark2Anchor;           /* array of mark glyph anchor
                                           tables                     */
  };

  typedef struct TTO_Mark2Record_  TTO_Mark2Record;


  struct TTO_Mark2Array_
  {
    TT_UShort         Mark2Count;       /* number of Mark2Record tables */
    TTO_Mark2Record*  Mark2Record;      /* array of Mark2Record tables  */
  };

  typedef struct TTO_Mark2Array_  TTO_Mark2Array;


  struct TTO_MarkMarkPos_
  {
    TT_UShort       PosFormat;          /* always 1                         */
    TTO_Coverage    Mark1Coverage;      /* first mark glyph coverage table  */
    TTO_Coverage    Mark2Coverage;      /* second mark glyph coverave table */
    TT_UShort       ClassCount;         /* number of combining mark classes */
    TTO_MarkArray   Mark1Array;         /* MarkArray table for first mark   */
    TTO_Mark2Array  Mark2Array;         /* MarkArray table for second mark  */
  };

  typedef struct TTO_MarkMarkPos_  TTO_MarkMarkPos;


  /* needed by both lookup type 7 and 8 */

  struct  TTO_PosLookupRecord_
  {
    TT_UShort  SequenceIndex;           /* index into current
                                           glyph sequence               */
    TT_UShort  LookupListIndex;         /* Lookup to apply to that pos. */
  };

  typedef struct TTO_PosLookupRecord_  TTO_PosLookupRecord;


  /* LookupType 7 */

  struct  TTO_PosRule_
  {
    TT_UShort             GlyphCount;   /* total number of input glyphs     */
    TT_UShort             PosCount;     /* number of PosLookupRecord tables */
    TT_UShort*            Input;        /* array of input glyph IDs         */
    TTO_PosLookupRecord*  PosLookupRecord;
                                        /* array of PosLookupRecord tables  */
  };

  typedef struct TTO_PosRule_  TTO_PosRule;


  struct  TTO_PosRuleSet_
  {
    TT_UShort     PosRuleCount;         /* number of PosRule tables */
    TTO_PosRule*  PosRule;              /* array of PosRule tables  */
  };

  typedef struct TTO_PosRuleSet_  TTO_PosRuleSet;


  struct  TTO_ContextPosFormat1_
  {
    TTO_Coverage     Coverage;          /* Coverage table              */
    TT_UShort        PosRuleSetCount;   /* number of PosRuleSet tables */
    TTO_PosRuleSet*  PosRuleSet;        /* array of PosRuleSet tables  */
  };

  typedef struct TTO_ContextPosFormat1_  TTO_ContextPosFormat1;


  struct  TTO_PosClassRule_
  {
    TT_UShort             GlyphCount;   /* total number of context classes  */
    TT_UShort             PosCount;     /* number of PosLookupRecord tables */
    TT_UShort*            Class;        /* array of classes                 */
    TTO_PosLookupRecord*  PosLookupRecord;
                                        /* array of PosLookupRecord tables  */
  };

  typedef struct TTO_PosClassRule_  TTO_PosClassRule;


  struct  TTO_PosClassSet_
  {
    TT_UShort          PosClassRuleCount;
                                        /* number of PosClassRule tables */
    TTO_PosClassRule*  PosClassRule;    /* array of PosClassRule tables  */
  };

  typedef struct TTO_PosClassSet_  TTO_PosClassSet;


  /* The `MaxContextLength' field is not defined in the TTO specification
     but simplifies the implementation of this format.  It holds the
     maximal context length used in the context rules.                    */

  struct  TTO_ContextPosFormat2_
  {
    TT_UShort            MaxContextLength;
                                        /* maximal context length       */
    TTO_Coverage         Coverage;      /* Coverage table               */
    TTO_ClassDefinition  ClassDef;      /* ClassDef table               */
    TT_UShort            PosClassSetCount;
                                        /* number of PosClassSet tables */
    TTO_PosClassSet*     PosClassSet;   /* array of PosClassSet tables  */
  };

  typedef struct TTO_ContextPosFormat2_  TTO_ContextPosFormat2;


  struct  TTO_ContextPosFormat3_
  {
    TT_UShort             GlyphCount;   /* number of input glyphs           */
    TT_UShort             PosCount;     /* number of PosLookupRecord tables */
    TTO_Coverage*         Coverage;     /* array of Coverage tables         */
    TTO_PosLookupRecord*  PosLookupRecord;
                                        /* array of PosLookupRecord tables  */
  };

  typedef struct TTO_ContextPosFormat3_  TTO_ContextPosFormat3;


  struct  TTO_ContextPos_
  {
    TT_UShort  PosFormat;               /* 1, 2, or 3     */

    union
    {
      TTO_ContextPosFormat1  cpf1;
      TTO_ContextPosFormat2  cpf2;
      TTO_ContextPosFormat3  cpf3;
    } cpf;
  };

  typedef struct TTO_ContextPos_  TTO_ContextPos;


  /* LookupType 8 */

  struct  TTO_ChainPosRule_
  {
    TT_UShort             BacktrackGlyphCount;
                                        /* total number of backtrack glyphs */
    TT_UShort*            Backtrack;    /* array of backtrack glyph IDs     */
    TT_UShort             InputGlyphCount;
                                        /* total number of input glyphs     */
    TT_UShort*            Input;        /* array of input glyph IDs         */
    TT_UShort             LookaheadGlyphCount;
                                        /* total number of lookahead glyphs */
    TT_UShort*            Lookahead;    /* array of lookahead glyph IDs     */
    TT_UShort             PosCount;     /* number of PosLookupRecords       */
    TTO_PosLookupRecord*  PosLookupRecord;
                                        /* array of PosLookupRecords       */
  };

  typedef struct TTO_ChainPosRule_  TTO_ChainPosRule;


  struct  TTO_ChainPosRuleSet_
  {
    TT_UShort          ChainPosRuleCount;
                                        /* number of ChainPosRule tables */
    TTO_ChainPosRule*  ChainPosRule;    /* array of ChainPosRule tables  */
  };

  typedef struct TTO_ChainPosRuleSet_  TTO_ChainPosRuleSet;


  struct  TTO_ChainContextPosFormat1_
  {
    TTO_Coverage          Coverage;     /* Coverage table                   */
    TT_UShort             ChainPosRuleSetCount;
                                        /* number of ChainPosRuleSet tables */
    TTO_ChainPosRuleSet*  ChainPosRuleSet;
                                        /* array of ChainPosRuleSet tables  */
  };

  typedef struct TTO_ChainContextPosFormat1_  TTO_ChainContextPosFormat1;


  struct  TTO_ChainPosClassRule_
  {
    TT_UShort             BacktrackGlyphCount;
                                        /* total number of backtrack
                                           classes                         */
    TT_UShort*            Backtrack;    /* array of backtrack classes      */
    TT_UShort             InputGlyphCount;
                                        /* total number of context classes */
    TT_UShort*            Input;        /* array of context classes        */
    TT_UShort             LookaheadGlyphCount;
                                        /* total number of lookahead
                                           classes                         */
    TT_UShort*            Lookahead;    /* array of lookahead classes      */
    TT_UShort             PosCount;     /* number of PosLookupRecords      */
    TTO_PosLookupRecord*  PosLookupRecord;
                                        /* array of substitution lookups   */
  };

  typedef struct TTO_ChainPosClassRule_  TTO_ChainPosClassRule;


  struct  TTO_ChainPosClassSet_
  {
    TT_UShort               ChainPosClassRuleCount;
                                        /* number of ChainPosClassRule
                                           tables                      */
    TTO_ChainPosClassRule*  ChainPosClassRule;
                                        /* array of ChainPosClassRule
                                           tables                      */
  };

  typedef struct TTO_ChainPosClassSet_  TTO_ChainPosClassSet;


  /* The `MaxXXXLength' fields are not defined in the TTO specification
     but simplifies the implementation of this format.  It holds the
     maximal context length used in the specific context rules.         */

  struct  TTO_ChainContextPosFormat2_
  {
    TTO_Coverage           Coverage;    /* Coverage table             */

    TT_UShort              MaxBacktrackLength;
                                        /* maximal backtrack length   */
    TTO_ClassDefinition    BacktrackClassDef;
                                        /* BacktrackClassDef table    */
    TT_UShort              MaxInputLength;
                                        /* maximal input length       */
    TTO_ClassDefinition    InputClassDef;
                                        /* InputClassDef table        */
    TT_UShort              MaxLookaheadLength;
                                        /* maximal lookahead length   */
    TTO_ClassDefinition    LookaheadClassDef;
                                        /* LookaheadClassDef table    */

    TT_UShort              ChainPosClassSetCount;
                                        /* number of ChainPosClassSet
                                           tables                     */
    TTO_ChainPosClassSet*  ChainPosClassSet;
                                        /* array of ChainPosClassSet
                                           tables                     */
  };

  typedef struct TTO_ChainContextPosFormat2_  TTO_ChainContextPosFormat2;


  struct  TTO_ChainContextPosFormat3_
  {
    TT_UShort             BacktrackGlyphCount;
                                        /* number of backtrack glyphs    */
    TTO_Coverage*         BacktrackCoverage;
                                        /* array of backtrack Coverage
                                           tables                        */
    TT_UShort             InputGlyphCount;
                                        /* number of input glyphs        */
    TTO_Coverage*         InputCoverage;
                                        /* array of input coverage
                                           tables                        */
    TT_UShort             LookaheadGlyphCount;
                                        /* number of lookahead glyphs    */
    TTO_Coverage*         LookaheadCoverage;
                                        /* array of lookahead coverage
                                           tables                        */
    TT_UShort             PosCount;     /* number of PosLookupRecords    */
    TTO_PosLookupRecord*  PosLookupRecord;
                                        /* array of substitution lookups */
  };

  typedef struct TTO_ChainContextPosFormat3_  TTO_ChainContextPosFormat3;


  struct  TTO_ChainContextPos_
  {
    TT_UShort  PosFormat;             /* 1, 2, or 3 */

    union
    {
      TTO_ChainContextPosFormat1  ccpf1;
      TTO_ChainContextPosFormat2  ccpf2;
      TTO_ChainContextPosFormat3  ccpf3;
    } ccpf;
  };

  typedef struct TTO_ChainContextPos_  TTO_ChainContextPos;


  union  TTO_GPOS_SubTable_
  {
    TTO_SinglePos        single;
    TTO_PairPos          pair;
    TTO_CursivePos       cursive;
    TTO_MarkBasePos      markbase;
    TTO_MarkLigPos       marklig;
    TTO_MarkMarkPos      markmark;
    TTO_ContextPos       context;
    TTO_ChainContextPos  chain;
  };

  typedef union TTO_GPOS_SubTable_  TTO_GPOS_SubTable;


  /* finally, the GPOS API */

  EXPORT_DEF
  TT_Error  TT_Init_GPOS_Extension( TT_Engine  engine );

  EXPORT_DEF
  TT_Error  TT_Load_GPOS_Table( TT_Face          face,
                                TTO_GPOSHeader*  gpos,
                                TTO_GDEFHeader*  gdef );

  EXPORT_DEF
  TT_Error  TT_GPOS_Select_Script( TTO_GPOSHeader*  gpos,
                                   TT_ULong         script_tag,
                                   TT_UShort*       script_index );
  EXPORT_DEF
  TT_Error  TT_GPOS_Select_Language( TTO_GPOSHeader*  gpos,
                                     TT_ULong         language_tag,
                                     TT_UShort        script_index,
                                     TT_UShort*       language_index,
                                     TT_UShort*       req_feature_index );
  EXPORT_DEF
  TT_Error  TT_GPOS_Select_Feature( TTO_GPOSHeader*  gpos,
                                    TT_ULong         feature_tag,
                                    TT_UShort        script_index,
                                    TT_UShort        language_index,
                                    TT_UShort*       feature_index );

  EXPORT_DEF
  TT_Error  TT_GPOS_Query_Scripts( TTO_GPOSHeader*  gpos,
                                   TT_ULong**       script_tag_list );
  EXPORT_DEF
  TT_Error  TT_GPOS_Query_Languages( TTO_GPOSHeader*  gpos,
                                     TT_UShort        script_index,
                                     TT_ULong**       language_tag_list );
  EXPORT_DEF
  TT_Error  TT_GPOS_Query_Features( TTO_GPOSHeader*  gpos,
                                    TT_UShort        script_index,
                                    TT_UShort        language_index,
                                    TT_ULong**       feature_tag_list );

  EXPORT_DEF
  TT_Error  TT_GPOS_Add_Feature( TTO_GPOSHeader*  gpos,
                                 TT_UShort        feature_index,
                                 TT_UShort        property );
  EXPORT_DEF
  TT_Error  TT_GPOS_Clear_Features( TTO_GPOSHeader*  gpos );

#ifdef __cplusplus
}
#endif

#endif /* FTXGPOS_H */


/* END */