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FreeType on OpenGL ES (iPhone)

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24 Nov 2010CPOL4 min read 86.4K   3K   27  
Faster, smarter and better looking fonts rendered with OpenGL ES
/***************************************************************************/
/*                                                                         */
/*  ftbitmap.c                                                             */
/*                                                                         */
/*    FreeType utility functions for bitmaps (body).                       */
/*                                                                         */
/*  Copyright 2004, 2005, 2006, 2007, 2008, 2009 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_BITMAP_H
#include FT_IMAGE_H
#include FT_INTERNAL_OBJECTS_H


  static
  const FT_Bitmap  null_bitmap = { 0, 0, 0, 0, 0, 0, 0, 0 };


  /* documentation is in ftbitmap.h */

  FT_EXPORT_DEF( void )
  FT_Bitmap_New( FT_Bitmap  *abitmap )
  {
    *abitmap = null_bitmap;
  }


  /* documentation is in ftbitmap.h */

  FT_EXPORT_DEF( FT_Error )
  FT_Bitmap_Copy( FT_Library        library,
                  const FT_Bitmap  *source,
                  FT_Bitmap        *target)
  {
    FT_Memory  memory = library->memory;
    FT_Error   error  = FT_Err_Ok;
    FT_Int     pitch  = source->pitch;
    FT_ULong   size;


    if ( source == target )
      return FT_Err_Ok;

    if ( source->buffer == NULL )
    {
      *target = *source;

      return FT_Err_Ok;
    }

    if ( pitch < 0 )
      pitch = -pitch;
    size = (FT_ULong)( pitch * source->rows );

    if ( target->buffer )
    {
      FT_Int    target_pitch = target->pitch;
      FT_ULong  target_size;


      if ( target_pitch < 0  )
        target_pitch = -target_pitch;
      target_size = (FT_ULong)( target_pitch * target->rows );

      if ( target_size != size )
        (void)FT_QREALLOC( target->buffer, target_size, size );
    }
    else
      (void)FT_QALLOC( target->buffer, size );

    if ( !error )
    {
      unsigned char *p;


      p = target->buffer;
      *target = *source;
      target->buffer = p;

      FT_MEM_COPY( target->buffer, source->buffer, size );
    }

    return error;
  }


  static FT_Error
  ft_bitmap_assure_buffer( FT_Memory   memory,
                           FT_Bitmap*  bitmap,
                           FT_UInt     xpixels,
                           FT_UInt     ypixels )
  {
    FT_Error        error;
    int             pitch;
    int             new_pitch;
    FT_UInt         bpp;
    FT_Int          i, width, height;
    unsigned char*  buffer;


    width  = bitmap->width;
    height = bitmap->rows;
    pitch  = bitmap->pitch;
    if ( pitch < 0 )
      pitch = -pitch;

    switch ( bitmap->pixel_mode )
    {
    case FT_PIXEL_MODE_MONO:
      bpp       = 1;
      new_pitch = ( width + xpixels + 7 ) >> 3;
      break;
    case FT_PIXEL_MODE_GRAY2:
      bpp       = 2;
      new_pitch = ( width + xpixels + 3 ) >> 2;
      break;
    case FT_PIXEL_MODE_GRAY4:
      bpp       = 4;
      new_pitch = ( width + xpixels + 1 ) >> 1;
      break;
    case FT_PIXEL_MODE_GRAY:
    case FT_PIXEL_MODE_LCD:
    case FT_PIXEL_MODE_LCD_V:
      bpp       = 8;
      new_pitch = ( width + xpixels );
      break;
    default:
      return FT_Err_Invalid_Glyph_Format;
    }

    /* if no need to allocate memory */
    if ( ypixels == 0 && new_pitch <= pitch )
    {
      /* zero the padding */
      FT_Int  bit_width = pitch * 8;
      FT_Int  bit_last  = ( width + xpixels ) * bpp;


      if ( bit_last < bit_width )
      {
        FT_Byte*  line  = bitmap->buffer + ( bit_last >> 3 );
        FT_Byte*  end   = bitmap->buffer + pitch;
        FT_Int    shift = bit_last & 7;
        FT_UInt   mask  = 0xFF00U >> shift;
        FT_Int    count = height;


        for ( ; count > 0; count--, line += pitch, end += pitch )
        {
          FT_Byte*  write = line;


          if ( shift > 0 )
          {
            write[0] = (FT_Byte)( write[0] & mask );
            write++;
          }
          if ( write < end )
            FT_MEM_ZERO( write, end-write );
        }
      }

      return FT_Err_Ok;
    }

    if ( FT_QALLOC_MULT( buffer, new_pitch, bitmap->rows + ypixels ) )
      return error;

    if ( bitmap->pitch > 0 )
    {
      FT_Int  len = ( width * bpp + 7 ) >> 3;


      for ( i = 0; i < bitmap->rows; i++ )
        FT_MEM_COPY( buffer + new_pitch * ( ypixels + i ),
                     bitmap->buffer + pitch * i, len );
    }
    else
    {
      FT_Int  len = ( width * bpp + 7 ) >> 3;


      for ( i = 0; i < bitmap->rows; i++ )
        FT_MEM_COPY( buffer + new_pitch * i,
                     bitmap->buffer + pitch * i, len );
    }

    FT_FREE( bitmap->buffer );
    bitmap->buffer = buffer;

    if ( bitmap->pitch < 0 )
      new_pitch = -new_pitch;

    /* set pitch only, width and height are left untouched */
    bitmap->pitch = new_pitch;

    return FT_Err_Ok;
  }


  /* documentation is in ftbitmap.h */

  FT_EXPORT_DEF( FT_Error )
  FT_Bitmap_Embolden( FT_Library  library,
                      FT_Bitmap*  bitmap,
                      FT_Pos      xStrength,
                      FT_Pos      yStrength )
  {
    FT_Error        error;
    unsigned char*  p;
    FT_Int          i, x, y, pitch;
    FT_Int          xstr, ystr;


    if ( !library )
      return FT_Err_Invalid_Library_Handle;

    if ( !bitmap || !bitmap->buffer )
      return FT_Err_Invalid_Argument;

    if ( ( ( FT_PIX_ROUND( xStrength ) >> 6 ) > FT_INT_MAX ) ||
         ( ( FT_PIX_ROUND( yStrength ) >> 6 ) > FT_INT_MAX ) )
      return FT_Err_Invalid_Argument;
       
    xstr = (FT_Int)FT_PIX_ROUND( xStrength ) >> 6;
    ystr = (FT_Int)FT_PIX_ROUND( yStrength ) >> 6;

    if ( xstr == 0 && ystr == 0 )
      return FT_Err_Ok;
    else if ( xstr < 0 || ystr < 0 )
      return FT_Err_Invalid_Argument;

    switch ( bitmap->pixel_mode )
    {
    case FT_PIXEL_MODE_GRAY2:
    case FT_PIXEL_MODE_GRAY4:
      {
        FT_Bitmap  tmp;
        FT_Int     align;


        if ( bitmap->pixel_mode == FT_PIXEL_MODE_GRAY2 )
          align = ( bitmap->width + xstr + 3 ) / 4;
        else
          align = ( bitmap->width + xstr + 1 ) / 2;

        FT_Bitmap_New( &tmp );

        error = FT_Bitmap_Convert( library, bitmap, &tmp, align );
        if ( error )
          return error;

        FT_Bitmap_Done( library, bitmap );
        *bitmap = tmp;
      }
      break;

    case FT_PIXEL_MODE_MONO:
      if ( xstr > 8 )
        xstr = 8;
      break;

    case FT_PIXEL_MODE_LCD:
      xstr *= 3;
      break;

    case FT_PIXEL_MODE_LCD_V:
      ystr *= 3;
      break;
    }

    error = ft_bitmap_assure_buffer( library->memory, bitmap, xstr, ystr );
    if ( error )
      return error;

    pitch = bitmap->pitch;
    if ( pitch > 0 )
      p = bitmap->buffer + pitch * ystr;
    else
    {
      pitch = -pitch;
      p = bitmap->buffer + pitch * ( bitmap->rows - 1 );
    }

    /* for each row */
    for ( y = 0; y < bitmap->rows ; y++ )
    {
      /*
       * Horizontally:
       *
       * From the last pixel on, make each pixel or'ed with the
       * `xstr' pixels before it.
       */
      for ( x = pitch - 1; x >= 0; x-- )
      {
        unsigned char tmp;


        tmp = p[x];
        for ( i = 1; i <= xstr; i++ )
        {
          if ( bitmap->pixel_mode == FT_PIXEL_MODE_MONO )
          {
            p[x] |= tmp >> i;

            /* the maximum value of 8 for `xstr' comes from here */
            if ( x > 0 )
              p[x] |= p[x - 1] << ( 8 - i );

#if 0
            if ( p[x] == 0xff )
              break;
#endif
          }
          else
          {
            if ( x - i >= 0 )
            {
              if ( p[x] + p[x - i] > bitmap->num_grays - 1 )
              {
                p[x] = (unsigned char)(bitmap->num_grays - 1);
                break;
              }
              else
              {
                p[x] = (unsigned char)(p[x] + p[x-i]);
                if ( p[x] == bitmap->num_grays - 1 )
                  break;
              }
            }
            else
              break;
          }
        }
      }

      /*
       * Vertically:
       *
       * Make the above `ystr' rows or'ed with it.
       */
      for ( x = 1; x <= ystr; x++ )
      {
        unsigned char*  q;


        q = p - bitmap->pitch * x;
        for ( i = 0; i < pitch; i++ )
          q[i] |= p[i];
      }

      p += bitmap->pitch;
    }

    bitmap->width += xstr;
    bitmap->rows += ystr;

    return FT_Err_Ok;
  }


  /* documentation is in ftbitmap.h */

  FT_EXPORT_DEF( FT_Error )
  FT_Bitmap_Convert( FT_Library        library,
                     const FT_Bitmap  *source,
                     FT_Bitmap        *target,
                     FT_Int            alignment )
  {
    FT_Error   error = FT_Err_Ok;
    FT_Memory  memory;


    if ( !library )
      return FT_Err_Invalid_Library_Handle;

    memory = library->memory;

    switch ( source->pixel_mode )
    {
    case FT_PIXEL_MODE_MONO:
    case FT_PIXEL_MODE_GRAY:
    case FT_PIXEL_MODE_GRAY2:
    case FT_PIXEL_MODE_GRAY4:
    case FT_PIXEL_MODE_LCD:
    case FT_PIXEL_MODE_LCD_V:
      {
        FT_Int   pad;
        FT_Long  old_size;


        old_size = target->rows * target->pitch;
        if ( old_size < 0 )
          old_size = -old_size;

        target->pixel_mode = FT_PIXEL_MODE_GRAY;
        target->rows       = source->rows;
        target->width      = source->width;

        pad = 0;
        if ( alignment > 0 )
        {
          pad = source->width % alignment;
          if ( pad != 0 )
            pad = alignment - pad;
        }

        target->pitch = source->width + pad;

        if ( target->rows * target->pitch > old_size             &&
             FT_QREALLOC( target->buffer,
                          old_size, target->rows * target->pitch ) )
          return error;
      }
      break;

    default:
      error = FT_Err_Invalid_Argument;
    }

    switch ( source->pixel_mode )
    {
    case FT_PIXEL_MODE_MONO:
      {
        FT_Byte*  s = source->buffer;
        FT_Byte*  t = target->buffer;
        FT_Int    i;


        target->num_grays = 2;

        for ( i = source->rows; i > 0; i-- )
        {
          FT_Byte*  ss = s;
          FT_Byte*  tt = t;
          FT_Int    j;


          /* get the full bytes */
          for ( j = source->width >> 3; j > 0; j-- )
          {
            FT_Int  val = ss[0]; /* avoid a byte->int cast on each line */


            tt[0] = (FT_Byte)( ( val & 0x80 ) >> 7 );
            tt[1] = (FT_Byte)( ( val & 0x40 ) >> 6 );
            tt[2] = (FT_Byte)( ( val & 0x20 ) >> 5 );
            tt[3] = (FT_Byte)( ( val & 0x10 ) >> 4 );
            tt[4] = (FT_Byte)( ( val & 0x08 ) >> 3 );
            tt[5] = (FT_Byte)( ( val & 0x04 ) >> 2 );
            tt[6] = (FT_Byte)( ( val & 0x02 ) >> 1 );
            tt[7] = (FT_Byte)(   val & 0x01 );

            tt += 8;
            ss += 1;
          }

          /* get remaining pixels (if any) */
          j = source->width & 7;
          if ( j > 0 )
          {
            FT_Int  val = *ss;


            for ( ; j > 0; j-- )
            {
              tt[0] = (FT_Byte)( ( val & 0x80 ) >> 7);
              val <<= 1;
              tt   += 1;
            }
          }

          s += source->pitch;
          t += target->pitch;
        }
      }
      break;


    case FT_PIXEL_MODE_GRAY:
    case FT_PIXEL_MODE_LCD:
    case FT_PIXEL_MODE_LCD_V:
      {
        FT_Int    width   = source->width;
        FT_Byte*  s       = source->buffer;
        FT_Byte*  t       = target->buffer;
        FT_Int    s_pitch = source->pitch;
        FT_Int    t_pitch = target->pitch;
        FT_Int    i;


        target->num_grays = 256;

        for ( i = source->rows; i > 0; i-- )
        {
          FT_ARRAY_COPY( t, s, width );

          s += s_pitch;
          t += t_pitch;
        }
      }
      break;


    case FT_PIXEL_MODE_GRAY2:
      {
        FT_Byte*  s = source->buffer;
        FT_Byte*  t = target->buffer;
        FT_Int    i;


        target->num_grays = 4;

        for ( i = source->rows; i > 0; i-- )
        {
          FT_Byte*  ss = s;
          FT_Byte*  tt = t;
          FT_Int    j;


          /* get the full bytes */
          for ( j = source->width >> 2; j > 0; j-- )
          {
            FT_Int  val = ss[0];


            tt[0] = (FT_Byte)( ( val & 0xC0 ) >> 6 );
            tt[1] = (FT_Byte)( ( val & 0x30 ) >> 4 );
            tt[2] = (FT_Byte)( ( val & 0x0C ) >> 2 );
            tt[3] = (FT_Byte)( ( val & 0x03 ) );

            ss += 1;
            tt += 4;
          }

          j = source->width & 3;
          if ( j > 0 )
          {
            FT_Int  val = ss[0];


            for ( ; j > 0; j-- )
            {
              tt[0]  = (FT_Byte)( ( val & 0xC0 ) >> 6 );
              val  <<= 2;
              tt    += 1;
            }
          }

          s += source->pitch;
          t += target->pitch;
        }
      }
      break;


    case FT_PIXEL_MODE_GRAY4:
      {
        FT_Byte*  s = source->buffer;
        FT_Byte*  t = target->buffer;
        FT_Int    i;


        target->num_grays = 16;

        for ( i = source->rows; i > 0; i-- )
        {
          FT_Byte*  ss = s;
          FT_Byte*  tt = t;
          FT_Int    j;


          /* get the full bytes */
          for ( j = source->width >> 1; j > 0; j-- )
          {
            FT_Int  val = ss[0];


            tt[0] = (FT_Byte)( ( val & 0xF0 ) >> 4 );
            tt[1] = (FT_Byte)( ( val & 0x0F ) );

            ss += 1;
            tt += 2;
          }

          if ( source->width & 1 )
            tt[0] = (FT_Byte)( ( ss[0] & 0xF0 ) >> 4 );

          s += source->pitch;
          t += target->pitch;
        }
      }
      break;


    default:
      ;
    }

    return error;
  }


  /* documentation is in ftbitmap.h */

  FT_EXPORT_DEF( FT_Error )
  FT_GlyphSlot_Own_Bitmap( FT_GlyphSlot  slot )
  {
    if ( slot && slot->format == FT_GLYPH_FORMAT_BITMAP   &&
         !( slot->internal->flags & FT_GLYPH_OWN_BITMAP ) )
    {
      FT_Bitmap  bitmap;
      FT_Error   error;


      FT_Bitmap_New( &bitmap );
      error = FT_Bitmap_Copy( slot->library, &slot->bitmap, &bitmap );
      if ( error )
        return error;

      slot->bitmap = bitmap;
      slot->internal->flags |= FT_GLYPH_OWN_BITMAP;
    }

    return FT_Err_Ok;
  }


  /* documentation is in ftbitmap.h */

  FT_EXPORT_DEF( FT_Error )
  FT_Bitmap_Done( FT_Library  library,
                  FT_Bitmap  *bitmap )
  {
    FT_Memory  memory;


    if ( !library )
      return FT_Err_Invalid_Library_Handle;

    if ( !bitmap )
      return FT_Err_Invalid_Argument;

    memory = library->memory;

    FT_FREE( bitmap->buffer );
    *bitmap = null_bitmap;

    return FT_Err_Ok;
  }


/* END */

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer Astronautz
Spain Spain
After working in the software industry for many years, I've started my own games company that specialises in strategy games for mobile platforms.

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