ttmtx.c

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/***************************************************************************/
/*                                                                         */
/*  ttmtx.c                                                                */
/*                                                                         */
/*    Load the metrics tables common to TTF and OTF fonts (body).          */
/*                                                                         */
/*  Copyright 2006, 2007 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.                                        */
/*                                                                         */
/***************************************************************************/


#include <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_TRUETYPE_TAGS_H
#include "ttmtx.h"

#include "sferrors.h"


  /*************************************************************************/
  /*                                                                       */
  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  /* messages during execution.                                            */
  /*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_ttmtx


  /*
   *  Unfortunately, we can't enable our memory optimizations if
   *  FT_CONFIG_OPTION_OLD_INTERNALS is defined.  This is because at least
   *  one rogue client (libXfont in the X.Org XServer) is directly accessing
   *  the metrics.
   */

  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_hmtx                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Load the `hmtx' or `vmtx' table into a face object.                */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face     :: A handle to the target face object.                    */
  /*                                                                       */
  /*    stream   :: The input stream.                                      */
  /*                                                                       */
  /*    vertical :: A boolean flag.  If set, load `vmtx'.                  */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
#if !defined FT_CONFIG_OPTION_OLD_INTERNALS

  FT_LOCAL_DEF( FT_Error )
  tt_face_load_hmtx( TT_Face    face,
                     FT_Stream  stream,
                     FT_Bool    vertical )
  {
    FT_Error   error;
    FT_ULong   tag, table_size;
    FT_ULong*  ptable_offset;
    FT_ULong*  ptable_size;


    if ( vertical )
    {
      tag           = TTAG_vmtx;
      ptable_offset = &face->vert_metrics_offset;
      ptable_size   = &face->vert_metrics_size;
    }
    else
    {
      tag           = TTAG_hmtx;
      ptable_offset = &face->horz_metrics_offset;
      ptable_size   = &face->horz_metrics_size;
    }

    error = face->goto_table( face, tag, stream, &table_size );
    if ( error )
      goto Fail;

    *ptable_size   = table_size;
    *ptable_offset = FT_STREAM_POS();

  Fail:
    return error;
  }

#else /* !OPTIMIZE_MEMORY || OLD_INTERNALS */

  FT_LOCAL_DEF( FT_Error )
  tt_face_load_hmtx( TT_Face    face,
                     FT_Stream  stream,
                     FT_Bool    vertical )
  {
    FT_Error   error;
    FT_Memory  memory = stream->memory;

    FT_ULong   table_len;
    FT_Long    num_shorts, num_longs, num_shorts_checked;

    TT_LongMetrics *   longs;
    TT_ShortMetrics**  shorts;
    FT_Byte*           p;


    if ( vertical )
    {
      error = face->goto_table( face, TTAG_vmtx, stream, &table_len );
      if ( error )
        goto Fail;

      num_longs = face->vertical.number_Of_VMetrics;
      if ( (FT_ULong)num_longs > table_len / 4 )
        num_longs = (FT_Long)(table_len / 4);

      face->vertical.number_Of_VMetrics = 0;

      longs  = (TT_LongMetrics *)&face->vertical.long_metrics;
      shorts = (TT_ShortMetrics**)&face->vertical.short_metrics;
    }
    else
    {
      error = face->goto_table( face, TTAG_hmtx, stream, &table_len );
      if ( error )
        goto Fail;

      num_longs = face->horizontal.number_Of_HMetrics;
      if ( (FT_ULong)num_longs > table_len / 4 )
        num_longs = (FT_Long)(table_len / 4);

      face->horizontal.number_Of_HMetrics = 0;

      longs  = (TT_LongMetrics *)&face->horizontal.long_metrics;
      shorts = (TT_ShortMetrics**)&face->horizontal.short_metrics;
    }

    /* never trust derived values */

    num_shorts         = face->max_profile.numGlyphs - num_longs;
    num_shorts_checked = ( table_len - num_longs * 4L ) / 2;

    if ( num_shorts < 0 )
    {
      FT_ERROR(( "%cmtx has more metrics than glyphs.\n" ));

      /* Adobe simply ignores this problem.  So we shall do the same. */
#if 0
      error = vertical ? SFNT_Err_Invalid_Vert_Metrics
                       : SFNT_Err_Invalid_Horiz_Metrics;
      goto Exit;
#else
      num_shorts = 0;
#endif
    }

    if ( FT_QNEW_ARRAY( *longs,  num_longs  ) ||
         FT_QNEW_ARRAY( *shorts, num_shorts ) )
      goto Fail;

    if ( FT_FRAME_ENTER( table_len ) )
      goto Fail;

    p = stream->cursor;

    {
      TT_LongMetrics  cur   = *longs;
      TT_LongMetrics  limit = cur + num_longs;


      for ( ; cur < limit; cur++ )
      {
        cur->advance = FT_NEXT_USHORT( p );
        cur->bearing = FT_NEXT_SHORT( p );
      }
    }

    /* do we have an inconsistent number of metric values? */
    {
      TT_ShortMetrics*  cur   = *shorts;
      TT_ShortMetrics*  limit = cur +
                                FT_MIN( num_shorts, num_shorts_checked );


      for ( ; cur < limit; cur++ )
        *cur = FT_NEXT_SHORT( p );

      /* We fill up the missing left side bearings with the     */
      /* last valid value.  Since this will occur for buggy CJK */
      /* fonts usually only, nothing serious will happen.       */
      if ( num_shorts > num_shorts_checked && num_shorts_checked > 0 )
      {
        FT_Short  val = (*shorts)[num_shorts_checked - 1];


        limit = *shorts + num_shorts;
        for ( ; cur < limit; cur++ )
          *cur = val;
      }
    }

    FT_FRAME_EXIT();

    if ( vertical )
      face->vertical.number_Of_VMetrics = (FT_UShort)num_longs;
    else
      face->horizontal.number_Of_HMetrics = (FT_UShort)num_longs;

  Fail:
    return error;
  }

#endif /* !OPTIMIZE_MEMORY || OLD_INTERNALS */