ftxgpos.c

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/*******************************************************************
 *
 *  ftxgpos.c
 *
 *    TrueType Open GPOS table support.
 *
 *  Copyright 1996-2001 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.
 *
 ******************************************************************/

/* XXX There is *a lot* of duplicated code (cf. formats 7 and 8), but
       I don't care currently.  I believe that it would be possible to
       save about 50% of TTO code by carefully designing the structures,
       sharing as much as possible with extensive use of macros.  This
       is something for a volunteer :-)                                  */

#include "tttypes.h"
#include "tttags.h"
#include "ttload.h"
#include "ttextend.h"
#include "ttmemory.h"
#include "ttfile.h"

#include "ftxopen.h"
#include "ftxopenf.h"


  struct  GPOS_Instance_
  {
    TTO_GPOSHeader*  gpos;
    TT_Instance      instance;
    TT_Glyph         glyph;
    UShort           load_flags;  /* how the glyph should be loaded */
    TT_Bool          r2l;

    UShort           first;       /* the first glyph in a chain of
                                     cursive connections           */
    UShort           last;        /* the last valid glyph -- used
                                     with cursive positioning     */
    TT_Pos           anchor_x;    /* the coordinates of the anchor point */
    TT_Pos           anchor_y;    /* of the last valid glyph             */
  };

  typedef struct GPOS_Instance_  GPOS_Instance;


  static TT_Error  Do_Glyph_Lookup( GPOS_Instance*    gpi,
                                    UShort            lookup_index,
                                    TTO_GSUB_String*  in,
                                    TTO_GPOS_Data*    out,
                                    UShort            context_length,
                                    int               nesting_level );



  /**********************
   * Extension Functions
   **********************/

  /* the client application must replace this with something more
     meaningful if multiple master fonts are to be supported.     */

  static TT_Error  default_mmfunc( TT_Instance  instance,
                                   TT_UShort    metric_id,
                                   TT_Pos*      metric_value,
                                   void*        data )
  {
    return TTO_Err_No_MM_Interpreter;
  }


  static TT_Error  GPOS_Create( void*  ext,
                                PFace  face )
  {
    DEFINE_LOAD_LOCALS( face->stream );

    TTO_GPOSHeader*  gpos = (TTO_GPOSHeader*)ext;
    Long             table;


    /* by convention */

    if ( !gpos )
      return TT_Err_Ok;

    /* a null offset indicates that there is no GPOS table */

    gpos->offset = 0;

    /* we store the start offset and the size of the subtable */

    table = TT_LookUp_Table( face, TTAG_GPOS );
    if ( table < 0 )
      return TT_Err_Ok;             /* The table is optional */

    if ( FILE_Seek( face->dirTables[table].Offset ) ||
         ACCESS_Frame( 4L ) )
      return error;

    gpos->offset  = FILE_Pos() - 4L;    /* undo ACCESS_Frame() */
    gpos->Version = GET_ULong();

    FORGET_Frame();

    /* a default mmfunc() handler which just returns an error */

    gpos->mmfunc = default_mmfunc;

    /* the default glyph function is TT_Load_Glyph() */

    gpos->gfunc = TT_Load_Glyph;

    gpos->loaded = FALSE;

    return TT_Err_Ok;
  }


  static TT_Error  GPOS_Destroy( void*  ext,
                                 PFace  face )
  {
    TTO_GPOSHeader*  gpos = (TTO_GPOSHeader*)ext;


    /* by convention */

    if ( !gpos )
      return TT_Err_Ok;

    if ( gpos->loaded )
    {
      Free_LookupList( &gpos->LookupList, GPOS );
      Free_FeatureList( &gpos->FeatureList );
      Free_ScriptList( &gpos->ScriptList );
    }

    return TT_Err_Ok;
  }


  FT_EXPORT_FUNC( TT_Error )
  TT_Init_GPOS_Extension( TT_Engine  engine )
  {
    PEngine_Instance  _engine = HANDLE_Engine( engine );


    if ( !_engine )
      return TT_Err_Invalid_Engine;

    return  TT_Register_Extension( _engine,
                                   GPOS_ID,
                                   sizeof ( TTO_GPOSHeader ),
                                   GPOS_Create,
                                   GPOS_Destroy );
  }


  FT_EXPORT_FUNC( TT_Error )
  TT_Load_GPOS_Table( TT_Face          face,
                      TTO_GPOSHeader*  retptr,
                      TTO_GDEFHeader*  gdef )
  {
    ULong            cur_offset, new_offset, base_offset;

    UShort           i, num_lookups;
    TTO_GPOSHeader*  gpos;
    TTO_GDEFHeader*  gdef_reg;
    TTO_Lookup*      lo;

    PFace  faze = HANDLE_Face( face );
    DEFINE_ALL_LOCALS;


    if ( !retptr )
      return TT_Err_Invalid_Argument;

    if ( !faze )
      return TT_Err_Invalid_Face_Handle;

    error = TT_Extension_Get( faze, GPOS_ID, (void**)&gpos );
    if ( error )
      return error;

    if ( gpos->offset == 0 )
      return TT_Err_Table_Missing;      /* no GPOS table; nothing to do */

    /* now access stream */

    if ( USE_Stream( faze->stream, stream ) )
      return error;

    base_offset = gpos->offset;

    /* skip version */

    if ( FILE_Seek( base_offset + 4L ) ||
         ACCESS_Frame( 2L ) )
      return error;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_ScriptList( &gpos->ScriptList,
                                    faze ) ) != TT_Err_Ok )
      return error;
    (void)FILE_Seek( cur_offset );

    if ( ACCESS_Frame( 2L ) )
      goto Fail3;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_FeatureList( &gpos->FeatureList,
                                     faze ) ) != TT_Err_Ok )
      goto Fail3;
    (void)FILE_Seek( cur_offset );

    if ( ACCESS_Frame( 2L ) )
      goto Fail2;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_LookupList( &gpos->LookupList,
                                    faze, GPOS ) ) != TT_Err_Ok )
      goto Fail2;

    gpos->gdef = gdef;      /* can be NULL */

    /* We now check the LookupFlags for values larger than 0xFF to find
       out whether we need to load the `MarkAttachClassDef' field of the
       GDEF table -- this hack is necessary for OpenType 1.2 tables since
       the version field of the GDEF table hasn't been incremented.

       For constructed GDEF tables, we only load it if
       `MarkAttachClassDef_offset' is not zero (nevertheless, a build of
       a constructed mark attach table is not supported currently).       */

    if ( gdef &&
         gdef->MarkAttachClassDef_offset && !gdef->MarkAttachClassDef.loaded )
    {
      lo          = gpos->LookupList.Lookup;
      num_lookups = gpos->LookupList.LookupCount;

      for ( i = 0; i < num_lookups; i++ )
      {
        if ( lo[i].LookupFlag & IGNORE_SPECIAL_MARKS )
        {
          if ( FILE_Seek( gdef->MarkAttachClassDef_offset ) ||
               ACCESS_Frame( 2L ) )
            goto Fail1;

          new_offset = GET_UShort();

          FORGET_Frame();

          if ( !new_offset )
            return TTO_Err_Invalid_GDEF_SubTable;

          new_offset += gdef->offset;

          if ( FILE_Seek( new_offset ) ||
               ( error = Load_ClassDefinition( &gdef->MarkAttachClassDef,
                                               256, faze ) ) != TT_Err_Ok )
            goto Fail1;

          /* copy the class definition pointer into the extension structure */

          error = TT_Extension_Get( faze, GDEF_ID, (void**)&gdef_reg );
          if ( error )
            return error;

          *gdef_reg = *gdef;

          break;
        }
      }
    }

    gpos->loaded = TRUE;
    *retptr = *gpos;
    DONE_Stream( stream );

    return TT_Err_Ok;

  Fail1:
    Free_LookupList( &gpos->LookupList, GPOS );

  Fail2:
    Free_FeatureList( &gpos->FeatureList );

  Fail3:
    Free_ScriptList( &gpos->ScriptList );

    /* release stream */

    DONE_Stream( stream );

    return error;
  }



  /*****************************
   * SubTable related functions
   *****************************/

  /* shared tables */

  /* ValueRecord */

  /* There is a subtle difference in the specs between a `table' and a
     `record' -- offsets for device tables in ValueRecords are taken from
     the parent table and not the parent record.                          */

  static TT_Error  Load_ValueRecord( TTO_ValueRecord*  vr,
                                     UShort            format,
                                     ULong             base_offset,
                                     PFace             input )
  {
    DEFINE_LOAD_LOCALS( input->stream );

    ULong    cur_offset, new_offset;


    if ( format & HAVE_X_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->XPlacement = GET_Short();

      FORGET_Frame();
    }
    else
      vr->XPlacement = 0;

    if ( format & HAVE_Y_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->YPlacement = GET_Short();

      FORGET_Frame();
    }
    else
      vr->YPlacement = 0;

    if ( format & HAVE_X_ADVANCE )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->XAdvance = GET_Short();

      FORGET_Frame();
    }
    else
      vr->XAdvance = 0;

    if ( format & HAVE_Y_ADVANCE )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->YAdvance = GET_Short();

      FORGET_Frame();
    }
    else
      vr->YAdvance = 0;

    if ( format & HAVE_X_PLACEMENT_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->XPlacementDevice,
                                    input ) ) != TT_Err_Ok )
          return error;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty1;
    }
    else
    {
    empty1:
      vr->XPlacementDevice.StartSize  = 0;
      vr->XPlacementDevice.EndSize    = 0;
      vr->XPlacementDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_Y_PLACEMENT_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail3;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->YPlacementDevice,
                                    input ) ) != TT_Err_Ok )
          goto Fail3;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty2;
    }
    else
    {
    empty2:
      vr->YPlacementDevice.StartSize  = 0;
      vr->YPlacementDevice.EndSize    = 0;
      vr->YPlacementDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_X_ADVANCE_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail2;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->XAdvanceDevice,
                                    input ) ) != TT_Err_Ok )
          goto Fail2;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty3;
    }
    else
    {
    empty3:
      vr->XAdvanceDevice.StartSize  = 0;
      vr->XAdvanceDevice.EndSize    = 0;
      vr->XAdvanceDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_Y_ADVANCE_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail1;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->YAdvanceDevice,
                                    input ) ) != TT_Err_Ok )
          goto Fail1;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty4;
    }
    else
    {
    empty4:
      vr->YAdvanceDevice.StartSize  = 0;
      vr->YAdvanceDevice.EndSize    = 0;
      vr->YAdvanceDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_X_ID_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail1;

      vr->XIdPlacement = GET_UShort();

      FORGET_Frame();
    }
    else
      vr->XIdPlacement = 0;

    if ( format & HAVE_Y_ID_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail1;

      vr->YIdPlacement = GET_UShort();

      FORGET_Frame();
    }
    else
      vr->YIdPlacement = 0;