ttgload.c

a very goog book

/***************************************************************************/
/*                                                                         */
/*  ttgload.c                                                              */
/*                                                                         */
/*    TrueType Glyph Loader (body).                                        */
/*                                                                         */
/*  Copyright 1996-2001, 2002 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_CALC_H
#include FT_INTERNAL_STREAM_H
#include FT_INTERNAL_SFNT_H
#include FT_TRUETYPE_TAGS_H
#include FT_OUTLINE_H

#include "ttgload.h"

#include "tterrors.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_ttgload


  /*************************************************************************/
  /*                                                                       */
  /* Composite font flags.                                                 */
  /*                                                                       */
#define ARGS_ARE_WORDS       0x001
#define ARGS_ARE_XY_VALUES   0x002
#define ROUND_XY_TO_GRID     0x004
#define WE_HAVE_A_SCALE      0x008
/* reserved                  0x010 */
#define MORE_COMPONENTS      0x020
#define WE_HAVE_AN_XY_SCALE  0x040
#define WE_HAVE_A_2X2        0x080
#define WE_HAVE_INSTR        0x100
#define USE_MY_METRICS       0x200



  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_Get_Metrics                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Returns the horizontal or vertical metrics in font units for a     */
  /*    given glyph.  The metrics are the left side bearing (resp. top     */
  /*    side bearing) and advance width (resp. advance height).            */
  /*                                                                       */
  /* <Input>                                                               */
  /*    header  :: A pointer to either the horizontal or vertical metrics  */
  /*               structure.                                              */
  /*                                                                       */
  /*    idx     :: The glyph index.                                        */
  /*                                                                       */
  /* <Output>                                                              */
  /*    bearing :: The bearing, either left side or top side.              */
  /*                                                                       */
  /*    advance :: The advance width resp. advance height.                 */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This function will much probably move to another component in the  */
  /*    near future, but I haven't decided which yet.                      */
  /*                                                                       */
  FT_LOCAL_DEF( void )
  TT_Get_Metrics( TT_HoriHeader*  header,
                  FT_UInt         idx,
                  FT_Short*       bearing,
                  FT_UShort*      advance )
  {
    TT_LongMetrics  longs_m;
    FT_UShort       k = header->number_Of_HMetrics;


    if ( idx < (FT_UInt)k )
    {
      longs_m  = (TT_LongMetrics )header->long_metrics + idx;
      *bearing = longs_m->bearing;
      *advance = longs_m->advance;
    }
    else
    {
      *bearing = ((TT_ShortMetrics*)header->short_metrics)[idx - k];
      *advance = ((TT_LongMetrics )header->long_metrics)[k - 1].advance;
    }
  }


  /*************************************************************************/
  /*                                                                       */
  /* Returns the horizontal metrics in font units for a given glyph.  If   */
  /* `check' is true, take care of monospaced fonts by returning the       */
  /* advance width maximum.                                                */
  /*                                                                       */
  static void
  Get_HMetrics( TT_Face     face,
                FT_UInt     idx,
                FT_Bool     check,
                FT_Short*   lsb,
                FT_UShort*  aw )
  {
    TT_Get_Metrics( &face->horizontal, idx, lsb, aw );

    if ( check && face->postscript.isFixedPitch )
      *aw = face->horizontal.advance_Width_Max;
  }


  /*************************************************************************/
  /*                                                                       */
  /* Returns the advance width table for a given pixel size if it is found */
  /* in the font's `hdmx' table (if any).                                  */
  /*                                                                       */
  static FT_Byte*
  Get_Advance_Widths( TT_Face    face,
                      FT_UShort  ppem )
  {
    FT_UShort  n;


    for ( n = 0; n < face->hdmx.num_records; n++ )
      if ( face->hdmx.records[n].ppem == ppem )
        return face->hdmx.records[n].widths;

    return NULL;
  }


#define cur_to_org( n, zone ) \
          FT_MEM_COPY( (zone)->org, (zone)->cur, (n) * sizeof ( FT_Vector ) )

#define org_to_cur( n, zone ) \
          FT_MEM_COPY( (zone)->cur, (zone)->org, (n) * sizeof ( FT_Vector ) )


  /*************************************************************************/
  /*                                                                       */
  /* Translates an array of coordinates.                                   */
  /*                                                                       */
  static void
  translate_array( FT_UInt     n,
                   FT_Vector*  coords,
                   FT_Pos      delta_x,
                   FT_Pos      delta_y )
  {
    FT_UInt  k;


    if ( delta_x )
      for ( k = 0; k < n; k++ )
        coords[k].x += delta_x;

    if ( delta_y )
      for ( k = 0; k < n; k++ )
        coords[k].y += delta_y;
  }


  static void
  tt_prepare_zone( TT_GlyphZone  zone,
                   FT_GlyphLoad  load,
                   FT_UInt       start_point,
                   FT_UInt       start_contour )
  {
    zone->n_points   = (FT_UShort)( load->outline.n_points - start_point );
    zone->n_contours = (FT_Short) ( load->outline.n_contours - start_contour );
    zone->org        = load->extra_points + start_point;
    zone->cur        = load->outline.points + start_point;
    zone->tags       = (FT_Byte*)load->outline.tags + start_point;
    zone->contours   = (FT_UShort*)load->outline.contours + start_contour;
  }


#undef  IS_HINTED
#define IS_HINTED( flags )  ( ( flags & FT_LOAD_NO_HINTING ) == 0 )


  /*************************************************************************/
  /*                                                                       */
  /* The following functions are used by default with TrueType fonts.      */
  /* However, they can be replaced by alternatives if we need to support   */
  /* TrueType-compressed formats (like MicroType) in the future.           */
  /*                                                                       */
  /*************************************************************************/

  FT_CALLBACK_DEF( FT_Error )
  TT_Access_Glyph_Frame( TT_Loader  loader,
                         FT_UInt    glyph_index,
                         FT_ULong   offset,
                         FT_UInt    byte_count )
  {
    FT_Error   error;
    FT_Stream  stream = loader->stream;

    /* for non-debug mode */
    FT_UNUSED( glyph_index );


    FT_TRACE5(( "Glyph %ld\n", glyph_index ));

    /* the following line sets the `error' variable through macros! */
    if ( FT_STREAM_SEEK( offset ) || FT_FRAME_ENTER( byte_count ) )
      return error;

    return TT_Err_Ok;
  }


  FT_CALLBACK_DEF( void )
  TT_Forget_Glyph_Frame( TT_Loader  loader )
  {
    FT_Stream  stream = loader->stream;


    FT_FRAME_EXIT();
  }


  FT_CALLBACK_DEF( FT_Error )
  TT_Load_Glyph_Header( TT_Loader  loader )
  {
    FT_Stream  stream   = loader->stream;
    FT_Int     byte_len = loader->byte_len - 10;


    if ( byte_len < 0 )
      return TT_Err_Invalid_Outline;

    loader->n_contours = FT_GET_SHORT();

    loader->bbox.xMin = FT_GET_SHORT();
    loader->bbox.yMin = FT_GET_SHORT();
    loader->bbox.xMax = FT_GET_SHORT();
    loader->bbox.yMax = FT_GET_SHORT();

    FT_TRACE5(( "  # of contours: %d\n", loader->n_contours ));
    FT_TRACE5(( "  xMin: %4d  xMax: %4d\n", loader->bbox.xMin,
                                            loader->bbox.xMax ));
    FT_TRACE5(( "  yMin: %4d  yMax: %4d\n", loader->bbox.yMin,
                                            loader->bbox.yMax ));
    loader->byte_len = byte_len;

    return TT_Err_Ok;
  }


  FT_CALLBACK_DEF( FT_Error )
  TT_Load_Simple_Glyph( TT_Loader  load )
  {
    FT_Error        error;
    FT_Stream       stream     = load->stream;
    FT_GlyphLoader  gloader    = load->gloader;
    FT_Int          n_contours = load->n_contours;
    FT_Outline*     outline;
    TT_Face         face       = (TT_Face)load->face;
    TT_GlyphSlot    slot       = (TT_GlyphSlot)load->glyph;
    FT_UShort       n_ins;
    FT_Int          n, n_points;
    FT_Int          byte_len   = load->byte_len;


    /* reading the contours endpoints & number of points */
    {
      short*  cur   = gloader->current.outline.contours;
      short*  limit = cur + n_contours;


      /* check space for contours array + instructions count */
      byte_len -= 2 * ( n_contours + 1 );
      if ( byte_len < 0 )
        goto Invalid_Outline;

      for ( ; cur < limit; cur++ )
        cur[0] = FT_GET_USHORT();

      n_points = 0;
      if ( n_contours > 0 )
        n_points = cur[-1] + 1;

      error = FT_GlyphLoader_CheckPoints( gloader, n_points + 2, 0 );
      if ( error )
        goto Fail;

      /* we'd better check the contours table right now */
      outline = &gloader->current.outline;

      for ( cur = outline->contours + 1; cur < limit; cur++ )
        if ( cur[-1] >= cur[0] )
          goto Invalid_Outline;
    }

    /* reading the bytecode instructions */
    slot->control_len  = 0;
    slot->control_data = 0;

    n_ins = FT_GET_USHORT();

    FT_TRACE5(( "  Instructions size: %d\n", n_ins ));

    if ( n_ins > face->max_profile.maxSizeOfInstructions )
    {
      FT_TRACE0(( "TT_Load_Simple_Glyph: Too many instructions!\n" ));
      error = TT_Err_Too_Many_Hints;
      goto Fail;
    }

    byte_len -= n_ins;
    if ( byte_len < 0 )
    {
      FT_TRACE0(( "TT_Load_Simple_Glyph: Instruction count mismatch!\n" ));
      error = TT_Err_Too_Many_Hints;
      goto Fail;
    }

#ifdef TT_CONFIG_OPTION_BYTECODE_INTERPRETER

    if ( ( load->load_flags                        &
         ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING ) ) == 0 &&
           load->instructions )
    {
      slot->control_len  = n_ins;
      slot->control_data = load->instructions;

      FT_MEM_COPY( load->instructions, stream->cursor, n_ins );
    }

#endif /* TT_CONFIG_OPTION_BYTECODE_INTERPRETER */

    stream->cursor += n_ins;

    /* reading the point tags */
    {
      FT_Byte*  flag  = (FT_Byte*)outline->tags;
      FT_Byte*  limit = flag + n_points;
      FT_Byte   c, count;


      while ( flag < limit )
      {
        if ( --byte_len < 0 )
          goto Invalid_Outline;

        *flag++ = c = FT_GET_BYTE();
        if ( c & 8 )
        {
          if ( --byte_len < 0 )
            goto Invalid_Outline;

          count = FT_GET_BYTE();
          if ( flag + count > limit )
            goto Invalid_Outline;

          for ( ; count > 0; count-- )
            *flag++ = c;
        }
      }

      /* check that there is enough room to load the coordinates */
      for ( flag = (FT_Byte*)outline->tags; flag < limit; flag++ )
      {
        if ( *flag & 2 )
          byte_len -= 1;
        else if ( ( *flag & 16 ) == 0 )
          byte_len -= 2;

        if ( *flag & 4 )
          byte_len -= 1;
        else if ( ( *flag & 32 ) == 0 )
          byte_len -= 2;
      }

      if ( byte_len < 0 )
        goto Invalid_Outline;
    }

    /* reading the X coordinates */

    {
      FT_Vector*  vec   = outline->points;
      FT_Vector*  limit = vec + n_points;