ttsbit0.c

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/***************************************************************************/
/*                                                                         */
/*  ttsbit0.c                                                              */
/*                                                                         */
/*    TrueType and OpenType embedded bitmap support (body).                */
/*    This is a heap-optimized version.                                    */
/*                                                                         */
/*  Copyright 2005, 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.                                        */
/*                                                                         */
/***************************************************************************/


/* This file is included by ttsbit.c */


#include <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_TRUETYPE_TAGS_H
#include "ttsbit.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_ttsbit


    static const FT_Frame_Field  tt_sbit_line_metrics_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_SBit_LineMetricsRec

      /* no FT_FRAME_START */
        FT_FRAME_CHAR( ascender ),
        FT_FRAME_CHAR( descender ),
        FT_FRAME_BYTE( max_width ),

        FT_FRAME_CHAR( caret_slope_numerator ),
        FT_FRAME_CHAR( caret_slope_denominator ),
        FT_FRAME_CHAR( caret_offset ),

        FT_FRAME_CHAR( min_origin_SB ),
        FT_FRAME_CHAR( min_advance_SB ),
        FT_FRAME_CHAR( max_before_BL ),
        FT_FRAME_CHAR( min_after_BL ),
        FT_FRAME_CHAR( pads[0] ),
        FT_FRAME_CHAR( pads[1] ),
      FT_FRAME_END
    };

    static const FT_Frame_Field  tt_strike_start_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_SBit_StrikeRec

      /* no FT_FRAME_START */
        FT_FRAME_ULONG( ranges_offset ),
        FT_FRAME_SKIP_LONG,
        FT_FRAME_ULONG( num_ranges ),
        FT_FRAME_ULONG( color_ref ),
      FT_FRAME_END
    };

    static const FT_Frame_Field  tt_strike_end_fields[] =
    {
      /* no FT_FRAME_START */
        FT_FRAME_USHORT( start_glyph ),
        FT_FRAME_USHORT( end_glyph ),
        FT_FRAME_BYTE  ( x_ppem ),
        FT_FRAME_BYTE  ( y_ppem ),
        FT_FRAME_BYTE  ( bit_depth ),
        FT_FRAME_CHAR  ( flags ),
      FT_FRAME_END
    };


  FT_LOCAL_DEF( FT_Error )
  tt_face_load_eblc( TT_Face    face,
                     FT_Stream  stream )
  {
    FT_Error   error  = SFNT_Err_Ok;
    FT_Fixed   version;
    FT_ULong   num_strikes, table_size;
    FT_Byte*   p;
    FT_Byte*   p_limit;
    FT_UInt    count;


    face->sbit_num_strikes = 0;

    /* this table is optional */
    error = face->goto_table( face, TTAG_EBLC, stream, &table_size );
    if ( error )
      error = face->goto_table( face, TTAG_bloc, stream, &table_size );
    if ( error )
      goto Exit;

    if ( table_size < 8 )
    {
      FT_ERROR(( "%s: table too short!\n", "tt_face_load_sbit_strikes" ));
      error = SFNT_Err_Invalid_File_Format;
      goto Exit;
    }

    if ( FT_FRAME_EXTRACT( table_size, face->sbit_table ) )
      goto Exit;

    face->sbit_table_size = table_size;

    p       = face->sbit_table;
    p_limit = p + table_size;

    version     = FT_NEXT_ULONG( p );
    num_strikes = FT_NEXT_ULONG( p );

    if ( version != 0x00020000UL || num_strikes >= 0x10000UL )
    {
      FT_ERROR(( "%s: invalid table version!\n",
                 "tt_face_load_sbit_strikes" ));
      error = SFNT_Err_Invalid_File_Format;
      goto Fail;
    }

    /*
     *  Count the number of strikes available in the table.  We are a bit
     *  paranoid there and don't trust the data.
     */
    count = (FT_UInt)num_strikes;
    if ( 8 + 48UL * count > table_size )
      count = (FT_UInt)( ( p_limit - p ) / 48 );

    face->sbit_num_strikes = count;

    FT_TRACE3(( "sbit_num_strikes: %u\n", count ));
  Exit:
    return error;

  Fail:
    FT_FRAME_RELEASE( face->sbit_table );
    face->sbit_table_size = 0;
    goto Exit;
  }


  FT_LOCAL_DEF( void )
  tt_face_free_eblc( TT_Face  face )
  {
    FT_Stream  stream = face->root.stream;


    FT_FRAME_RELEASE( face->sbit_table );
    face->sbit_table_size  = 0;
    face->sbit_num_strikes = 0;
  }


  FT_LOCAL_DEF( FT_Error )
  tt_face_set_sbit_strike( TT_Face          face,
                           FT_Size_Request  req,
                           FT_ULong*        astrike_index )
  {
    return FT_Match_Size( (FT_Face)face, req, 0, astrike_index );
  }


  FT_LOCAL_DEF( FT_Error )
  tt_face_load_strike_metrics( TT_Face           face,
                               FT_ULong          strike_index,
                               FT_Size_Metrics*  metrics )
  {
    FT_Byte*         strike;


    if ( strike_index >= (FT_ULong)face->sbit_num_strikes )
      return SFNT_Err_Invalid_Argument;

    strike = face->sbit_table + 8 + strike_index * 48;

    metrics->x_ppem = (FT_UShort)strike[44];
    metrics->y_ppem = (FT_UShort)strike[45];

    metrics->ascender  = (FT_Char)strike[16] << 6;  /* hori.ascender  */
    metrics->descender = (FT_Char)strike[17] << 6;  /* hori.descender */
    metrics->height    = metrics->ascender - metrics->descender;

    /* XXX: Is this correct? */
    metrics->max_advance = ( (FT_Char)strike[22] + /* min_origin_SB  */
                                      strike[18] + /* max_width      */
                             (FT_Char)strike[23]   /* min_advance_SB */
                                                 ) << 6;

    return SFNT_Err_Ok;
  }


  typedef struct
  {
    TT_Face          face;
    FT_Stream        stream;
    FT_Bitmap*       bitmap;
    TT_SBit_Metrics  metrics;
    FT_Bool          metrics_loaded;
    FT_Bool          bitmap_allocated;
    FT_Byte          bit_depth;

    FT_ULong         ebdt_start;
    FT_ULong         ebdt_size;

    FT_ULong         strike_index_array;
    FT_ULong         strike_index_count;
    FT_Byte*         eblc_base;
    FT_Byte*         eblc_limit;

  } TT_SBitDecoderRec, *TT_SBitDecoder;


  static FT_Error
  tt_sbit_decoder_init( TT_SBitDecoder       decoder,
                        TT_Face              face,
                        FT_ULong             strike_index,
                        TT_SBit_MetricsRec*  metrics )
  {
    FT_Error   error;
    FT_Stream  stream     = face->root.stream;
    FT_ULong   ebdt_size;


    error = face->goto_table( face, TTAG_EBDT, stream, &ebdt_size );
    if ( error )
      error = face->goto_table( face, TTAG_bdat, stream, &ebdt_size );
    if ( error )
      goto Exit;

    decoder->face    = face;
    decoder->stream  = stream;
    decoder->bitmap  = &face->root.glyph->bitmap;
    decoder->metrics = metrics;

    decoder->metrics_loaded   = 0;
    decoder->bitmap_allocated = 0;

    decoder->ebdt_start = FT_STREAM_POS();
    decoder->ebdt_size  = ebdt_size;

    decoder->eblc_base  = face->sbit_table;
    decoder->eblc_limit = face->sbit_table + face->sbit_table_size;

    /* now find the strike corresponding to the index */
    {
      FT_Byte*  p = decoder->eblc_base + 8 + 48 * strike_index;


      decoder->strike_index_array = FT_NEXT_ULONG( p );
      p                          += 4;
      decoder->strike_index_count = FT_NEXT_ULONG( p );
      p                          += 34;
      decoder->bit_depth          = *p;
    }

  Exit:
    return error;
  }


  static void
  tt_sbit_decoder_done( TT_SBitDecoder  decoder )
  {
    FT_UNUSED( decoder );
  }


  static FT_Error
  tt_sbit_decoder_alloc_bitmap( TT_SBitDecoder  decoder )
  {
    FT_Error    error = SFNT_Err_Ok;
    FT_UInt     width, height;
    FT_Bitmap*  map = decoder->bitmap;
    FT_Long     size;


    if ( !decoder->metrics_loaded )
    {
      error = SFNT_Err_Invalid_Argument;
      goto Exit;
    }

    width  = decoder->metrics->width;
    height = decoder->metrics->height;

    map->width = (int)width;
    map->rows  = (int)height;

    switch ( decoder->bit_depth )
    {
    case 1:
      map->pixel_mode = FT_PIXEL_MODE_MONO;
      map->pitch      = ( map->width + 7 ) >> 3;
      break;

    case 2:
      map->pixel_mode = FT_PIXEL_MODE_GRAY2;
      map->pitch      = ( map->width + 3 ) >> 2;
      break;

    case 4:
      map->pixel_mode = FT_PIXEL_MODE_GRAY4;
      map->pitch      = ( map->width + 1 ) >> 1;
      break;

    case 8:
      map->pixel_mode = FT_PIXEL_MODE_GRAY;
      map->pitch      = map->width;
      break;

    default:
      error = SFNT_Err_Invalid_File_Format;
      goto Exit;
    }

    size = map->rows * map->pitch;

    /* check that there is no empty image */
    if ( size == 0 )
      goto Exit;     /* exit successfully! */

    error = ft_glyphslot_alloc_bitmap( decoder->face->root.glyph, size );
    if ( error )
      goto Exit;

    decoder->bitmap_allocated = 1;

  Exit:
    return error;
  }


  static FT_Error
  tt_sbit_decoder_load_metrics( TT_SBitDecoder  decoder,
                                FT_Byte*       *pp,
                                FT_Byte*        limit,
                                FT_Bool         big )
  {
    FT_Byte*         p       = *pp;
    TT_SBit_Metrics  metrics = decoder->metrics;


    if ( p + 5 > limit )
      goto Fail;

    if ( !decoder->metrics_loaded )
    {
      metrics->height       = p[0];
      metrics->width        = p[1];
      metrics->horiBearingX = (FT_Char)p[2];
      metrics->horiBearingY = (FT_Char)p[3];
      metrics->horiAdvance  = p[4];
    }

    p += 5;
    if ( big )
    {
      if ( p + 3 > limit )
        goto Fail;

      if ( !decoder->metrics_loaded )
      {
        metrics->vertBearingX = (FT_Char)p[0];
        metrics->vertBearingY = (FT_Char)p[1];
        metrics->vertAdvance  = p[2];
      }

      p += 3;
    }

    decoder->metrics_loaded = 1;
    *pp = p;
    return 0;

  Fail:
    return SFNT_Err_Invalid_Argument;
  }


  /* forward declaration */
  static FT_Error
  tt_sbit_decoder_load_image( TT_SBitDecoder  decoder,
                              FT_UInt         glyph_index,
                              FT_Int          x_pos,
                              FT_Int          y_pos );

  typedef FT_Error  (*TT_SBitDecoder_LoadFunc)( TT_SBitDecoder  decoder,
                                                FT_Byte*        p,
                                                FT_Byte*        plimit,
                                                FT_Int          x_pos,
                                                FT_Int          y_pos );


  static FT_Error
  tt_sbit_decoder_load_byte_aligned( TT_SBitDecoder  decoder,
                                     FT_Byte*        p,
                                     FT_Byte*        limit,
                                     FT_Int          x_pos,
                                     FT_Int          y_pos )
  {
    FT_Error    error = SFNT_Err_Ok;
    FT_Byte*    line;
    FT_Int      bit_height, bit_width, pitch, width, height, h;
    FT_Bitmap*  bitmap;


    if ( !decoder->bitmap_allocated )
    {
      error = tt_sbit_decoder_alloc_bitmap( decoder );
      if ( error )
        goto Exit;
    }

    /* check that we can write the glyph into the bitmap */
    bitmap     = decoder->bitmap;
    bit_width  = bitmap->width;
    bit_height = bitmap->rows;
    pitch      = bitmap->pitch;
    line       = bitmap->buffer;

    width  = decoder->metrics->width;
    height = decoder->metrics->height;

    if ( x_pos < 0 || x_pos + width > bit_width   ||
         y_pos < 0 || y_pos + height > bit_height )
    {
      error = SFNT_Err_Invalid_File_Format;
      goto Exit;
    }

    if ( p + ( ( width + 7 ) >> 3 ) * height > limit )
    {
      error = SFNT_Err_Invalid_File_Format;
      goto Exit;
    }

    /* now do the blit */
    line  += y_pos * pitch + ( x_pos >> 3 );
    x_pos &= 7;

    if ( x_pos == 0 )  /* the easy one */
    {
      for ( h = height; h > 0; h--, line += pitch )
      {
        FT_Byte*  write = line;
        FT_Int    w;


        for ( w = width; w >= 8; w -= 8 )
        {
          write[0] = (FT_Byte)( write[0] | *p++ );
          write   += 1;
        }

        if ( w > 0 )
          write[0] = (FT_Byte)( write[0] | ( *p++ & ( 0xFF00U >> w ) ) );
      }
    }
    else  /* x_pos > 0 */
    {
      for ( h = height; h > 0; h--, line += pitch )
      {
        FT_Byte*  write = line;
        FT_Int    w;
        FT_UInt   wval = 0;