ttsbit.c

qt-embedded-2.3.8.tar.gz源码

/***************************************************************************/
/*                                                                         */
/*  ttsbit.c                                                               */
/*                                                                         */
/*    TrueType and OpenType embedded bitmap support (body).                */
/*                                                                         */
/*  Copyright 1996-2000 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 <freetype/internal/ftdebug.h>
#include <freetype/internal/tterrors.h>
#include <freetype/internal/ftstream.h>
#include <freetype/tttags.h>


#ifdef FT_FLAT_COMPILE

#include "ttsbit.h"

#else

#include <sfnt/ttsbit.h>

#endif


  /*************************************************************************/
  /*                                                                       */
  /* 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


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    blit_sbit                                                          */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Blits a bitmap from an input stream into a given target.  Supports */
  /*    x and y offsets as well as byte padded lines.                      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    target      :: The target bitmap/pixmap.                           */
  /*                                                                       */
  /*    source      :: The input packed bitmap data.                       */
  /*                                                                       */
  /*    line_bits   :: The number of bits per line.                        */
  /*                                                                       */
  /*    byte_padded :: A flag which is true if lines are byte-padded.      */
  /*                                                                       */
  /*    x_offset    :: The horizontal offset.                              */
  /*                                                                       */
  /*    y_offset    :: The vertical offset.                                */
  /*                                                                       */
  /* <Note>                                                                */
  /*    IMPORTANT: The x and y offsets are relative to the top corner of   */
  /*               the target bitmap (unlike the normal TrueType           */
  /*               convention).  A positive y offset indicates a downwards */
  /*               direction!                                              */
  /*                                                                       */
  static
  void  blit_sbit( FT_Bitmap*  target,
                   FT_Byte*    source,
                   FT_Int      line_bits,
                   FT_Bool     byte_padded,
                   FT_Int      x_offset,
                   FT_Int      y_offset )
  {
    FT_Byte*   line_buff;
    FT_Int     line_incr;
    FT_Int     height;

    FT_UShort  acc;
    FT_Byte    loaded;


    /* first of all, compute starting write position */
    line_incr = target->pitch;
    line_buff = target->buffer;

    if ( line_incr < 0 )
      line_buff -= line_incr * ( target->rows - 1 );

    line_buff += ( x_offset >> 3 ) + y_offset * line_incr;

    /***********************************************************************/
    /*                                                                     */
    /* We use the extra-classic `accumulator' trick to extract the bits    */
    /* from the source byte stream.                                        */
    /*                                                                     */
    /* Namely, the variable `acc' is a 16-bit accumulator containing the   */
    /* last `loaded' bits from the input stream.  The bits are shifted to  */
    /* the upmost position in `acc'.                                       */
    /*                                                                     */
    /***********************************************************************/

    acc    = 0;  /* clear accumulator   */
    loaded = 0;  /* no bits were loaded */

    for ( height = target->rows; height > 0; height-- )
    {
      FT_Byte*  cur   = line_buff;    /* current write cursor          */
      FT_Int    count = line_bits;    /* # of bits to extract per line */
      FT_Byte   shift = x_offset & 7; /* current write shift           */
      FT_Byte   space = 8 - shift;


      /* first of all, read individual source bytes */
      if ( count >= 8 )
      {
        count -= 8;
        {
          do
          {
            FT_Byte  val;


            /* ensure that there are at least 8 bits in the accumulator */
            if ( loaded < 8 )
            {
              acc    |= (FT_UShort)*source++ << ( 8 - loaded );
              loaded += 8;
            }

            /* now write one byte */
            val = (FT_Byte)( acc >> 8 );
            if ( shift )
            {
              cur[0] |= val >> shift;
              cur[1] |= val << space;
            }
            else
              cur[0] |= val;

            cur++;
            acc   <<= 8;  /* remove bits from accumulator */
            loaded -= 8;
            count  -= 8;

          } while ( count >= 0 );
        }

        /* restore `count' to correct value */
        count += 8;
      }

      /* now write remaining bits (count < 8) */
      if ( count > 0 )
      {
        FT_Byte  val;


        /* ensure that there are at least `count' bits in the accumulator */
        if ( loaded < count )
        {
          acc    |= (FT_UShort)*source++ << ( 8 - loaded );
          loaded += 8;
        }

        /* now write remaining bits */
        val     = ( (FT_Byte)( acc >> 8 ) ) & ~( 0xFF >> count );
        cur[0] |= val >> shift;

        if ( count > space )
          cur[1] |= val << space;

        acc   <<= count;
        loaded -= count;
      }

      /* now, skip to next line */
      if ( byte_padded )
        acc = loaded = 0;   /* clear accumulator on byte-padded lines */

      line_buff += line_incr;
    }
  }


  const FT_Frame_Field  sbit_metrics_fields[] =
  {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_SBit_Metrics

    FT_FRAME_START( 8 ),
      FT_FRAME_BYTE( height ),
      FT_FRAME_BYTE( width ),

      FT_FRAME_CHAR( horiBearingX ),
      FT_FRAME_CHAR( horiBearingY ),
      FT_FRAME_BYTE( horiAdvance ),

      FT_FRAME_CHAR( vertBearingX ),
      FT_FRAME_CHAR( vertBearingY ),
      FT_FRAME_BYTE( vertAdvance ),
    FT_FRAME_END
  };


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_Load_SBit_Const_Metrics                                         */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the metrics for `EBLC' index tables format 2 and 5.          */
  /*                                                                       */
  /* <Input>                                                               */
  /*    range  :: The target range.                                        */
  /*                                                                       */
  /*    stream :: The input stream.                                        */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static
  FT_Error  Load_SBit_Const_Metrics( TT_SBit_Range*  range,
                                     FT_Stream       stream )
  {
    FT_Error  error;


    if ( READ_ULong( range->image_size ) )
      return error;

    return READ_Fields( sbit_metrics_fields, &range->metrics );
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_Load_SBit_Range_Codes                                           */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the range codes for `EBLC' index tables format 4 and 5.      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    range        :: The target range.                                  */
  /*                                                                       */
  /*    stream       :: The input stream.                                  */
  /*                                                                       */
  /*    load_offsets :: A flag whether to load the glyph offset table.     */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static
  FT_Error  Load_SBit_Range_Codes( TT_SBit_Range*  range,
                                   FT_Stream       stream,
                                   FT_Bool         load_offsets )
  {
    FT_Error   error;
    FT_ULong   count, n, size;
    FT_Memory  memory = stream->memory;


    if ( READ_ULong( count ) )
      goto Exit;

    range->num_glyphs = count;

    /* Allocate glyph offsets table if needed */
    if ( load_offsets )
    {
      if ( ALLOC_ARRAY( range->glyph_offsets, count, FT_ULong ) )
        goto Exit;

      size = count * 4L;
    }
    else
      size = count * 2L;

    /* Allocate glyph codes table and access frame */
    if ( ALLOC_ARRAY ( range->glyph_codes, count, FT_UShort ) ||
         ACCESS_Frame( size )                                 )
      goto Exit;

    for ( n = 0; n < count; n++ )
    {
      range->glyph_codes[n] = GET_UShort();

      if ( load_offsets )
        range->glyph_offsets[n] = (FT_ULong)range->image_offset +
                                  GET_UShort();
    }

    FORGET_Frame();

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_Load_SBit_Range                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads a given `EBLC' index/range table.                            */
  /*                                                                       */
  /* <Input>                                                               */
  /*    range  :: The target range.                                        */
  /*                                                                       */
  /*    stream :: The input stream.                                        */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static
  FT_Error  Load_SBit_Range( TT_SBit_Range*  range,
                             FT_Stream       stream )
  {
    FT_Error   error;
    FT_Memory  memory = stream->memory;


    switch( range->index_format )
    {
    case 1:   /* variable metrics with 4-byte offsets */
    case 3:   /* variable metrics with 2-byte offsets */
      {
        FT_ULong  num_glyphs, n;
        FT_Int    size_elem;
        FT_Bool   large = ( range->index_format == 1 );


        num_glyphs        = range->last_glyph - range->first_glyph + 1L;
        range->num_glyphs = num_glyphs;
        num_glyphs++;                       /* XXX: BEWARE - see spec */

        size_elem = large ? 4 : 2;

        if ( ALLOC_ARRAY( range->glyph_offsets,
                          num_glyphs, FT_ULong )    ||
             ACCESS_Frame( num_glyphs * size_elem ) )
          goto Exit;

        for ( n = 0; n < num_glyphs; n++ )
          range->glyph_offsets[n] = (FT_ULong)( range->image_offset +
                                                  ( large ? GET_ULong()
                                                          : GET_UShort() ) );
        FORGET_Frame();
      }
      break;

    case 2:   /* all glyphs have identical metrics */
      error = Load_SBit_Const_Metrics( range, stream );
      break;

    case 4:
      error = Load_SBit_Range_Codes( range, stream, 1 );
      break;

    case 5:
      error = Load_SBit_Const_Metrics( range, stream ) ||