summaryrefslogblamecommitdiff
path: root/src/static_libs/freetype/sw_ft_raster.c
blob: b2d96aaf2ff034c548dd401d142d9dfe177c5f7e (plain) (tree)
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234








































































                                                                             



                                  

























                                                                           

                                                         


                                                                             







































































































                                                                      
                     























































                                                                         







                                                                     







































































                                                                                  

                  








































                                                    
                         































































































































































































                                                                             




                                     

                                                                             
                                                                             




                                                                             

                                       

 



                         

                                   


                                                      
 

                      
 

                                   
 


                                                                   
     

                                         
     
                       
     



















                                                                  
     
                                                              
     


                                        
 
 



                                                                       
       

                                                                          
         











































                                                                           

         

                                           

     




                                               



                       

   





























































































































































































































































































































































































































































































































                                                                                                            














































                                                                           



















                                                             

























                                                             











                                                                         







                                                                            




























                                                                         





                                                                           






                                                                             








                                                        


             



























































































































































                                                                             



















                                                   



                                                          
                                                                             
 
                            
 





                                                                 















                                                             













                                                            
                                                    



                                  
                                   
                           
                           






                                                                      


























                                                                         


                              












                                                   
/***************************************************************************/
/*                                                                         */
/*  ftgrays.c                                                              */
/*                                                                         */
/*    A new `perfect' anti-aliasing renderer (body).                       */
/*                                                                         */
/*  Copyright 2000-2003, 2005-2014 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 is a new anti-aliasing scan-converter for FreeType 2.  The       */
  /* algorithm used here is _very_ different from the one in the standard  */
  /* `ftraster' module.  Actually, `ftgrays' computes the _exact_          */
  /* coverage of the outline on each pixel cell.                           */
  /*                                                                       */
  /* It is based on ideas that I initially found in Raph Levien's          */
  /* excellent LibArt graphics library (see http://www.levien.com/libart   */
  /* for more information, though the web pages do not tell anything       */
  /* about the renderer; you'll have to dive into the source code to       */
  /* understand how it works).                                             */
  /*                                                                       */
  /* Note, however, that this is a _very_ different implementation         */
  /* compared to Raph's.  Coverage information is stored in a very         */
  /* different way, and I don't use sorted vector paths.  Also, it doesn't */
  /* use floating point values.                                            */
  /*                                                                       */
  /* This renderer has the following advantages:                           */
  /*                                                                       */
  /* - It doesn't need an intermediate bitmap.  Instead, one can supply a  */
  /*   callback function that will be called by the renderer to draw gray  */
  /*   spans on any target surface.  You can thus do direct composition on */
  /*   any kind of bitmap, provided that you give the renderer the right   */
  /*   callback.                                                           */
  /*                                                                       */
  /* - A perfect anti-aliaser, i.e., it computes the _exact_ coverage on   */
  /*   each pixel cell.                                                    */
  /*                                                                       */
  /* - It performs a single pass on the outline (the `standard' FT2        */
  /*   renderer makes two passes).                                         */
  /*                                                                       */
  /* - It can easily be modified to render to _any_ number of gray levels  */
  /*   cheaply.                                                            */
  /*                                                                       */
  /* - For small (< 20) pixel sizes, it is faster than the standard        */
  /*   renderer.                                                           */
  /*                                                                       */
  /*************************************************************************/


#include "sw_ft_raster.h"
#include "sw_ft_math.h"

  /* Auxiliary macros for token concatenation. */
#define SW_FT_ERR_XCAT( x, y )  x ## y
#define SW_FT_ERR_CAT( x, y )   SW_FT_ERR_XCAT( x, y )

#define SW_FT_BEGIN_STMNT  do {
#define SW_FT_END_STMNT    } while ( 0 )


#include <stddef.h>
#include <string.h>
#include <setjmp.h>
#include <limits.h>
#define SW_FT_UINT_MAX   UINT_MAX
#define SW_FT_INT_MAX    INT_MAX
#define SW_FT_ULONG_MAX  ULONG_MAX
#define SW_FT_CHAR_BIT   CHAR_BIT

#define ft_memset   memset

#define ft_setjmp   setjmp
#define ft_longjmp  longjmp
#define ft_jmp_buf  jmp_buf

typedef ptrdiff_t  SW_FT_PtrDist;


#define ErrRaster_Invalid_Mode      -2
#define ErrRaster_Invalid_Outline   -1
#define ErrRaster_Invalid_Argument  -3
#define ErrRaster_Memory_Overflow   -4

#define SW_FT_BEGIN_HEADER
#define SW_FT_END_HEADER


  /* This macro is used to indicate that a function parameter is unused. */
  /* Its purpose is simply to reduce compiler warnings.  Note also that  */
  /* simply defining it as `(void)x' doesn't avoid warnings with certain */
  /* ANSI compilers (e.g. LCC).                                          */
#define SW_FT_UNUSED( x )  (x) = (x)


#define SW_FT_THROW( e )   SW_FT_ERR_CAT( ErrRaster_, e )

  /* The size in bytes of the render pool used by the scan-line converter  */
  /* to do all of its work.                                                */
#define SW_FT_RENDER_POOL_SIZE  16384L

typedef int
(*SW_FT_Outline_MoveToFunc)( const SW_FT_Vector*  to,
                          void*             user );

#define SW_FT_Outline_MoveTo_Func  SW_FT_Outline_MoveToFunc

typedef int
(*SW_FT_Outline_LineToFunc)( const SW_FT_Vector*  to,
                          void*             user );

#define SW_FT_Outline_LineTo_Func  SW_FT_Outline_LineToFunc


typedef int
(*SW_FT_Outline_ConicToFunc)( const SW_FT_Vector*  control,
                           const SW_FT_Vector*  to,
                           void*             user );

#define SW_FT_Outline_ConicTo_Func  SW_FT_Outline_ConicToFunc

typedef int
(*SW_FT_Outline_CubicToFunc)( const SW_FT_Vector*  control1,
                           const SW_FT_Vector*  control2,
                           const SW_FT_Vector*  to,
                           void*             user );

#define SW_FT_Outline_CubicTo_Func  SW_FT_Outline_CubicToFunc

typedef struct  SW_FT_Outline_Funcs_
{
  SW_FT_Outline_MoveToFunc   move_to;
  SW_FT_Outline_LineToFunc   line_to;
  SW_FT_Outline_ConicToFunc  conic_to;
  SW_FT_Outline_CubicToFunc  cubic_to;

  int                        shift;
  SW_FT_Pos                  delta;

} SW_FT_Outline_Funcs;



#define SW_FT_DEFINE_OUTLINE_FUNCS( class_,               \
                                 move_to_, line_to_,   \
                                 conic_to_, cubic_to_, \
                                 shift_, delta_ )      \
          static const SW_FT_Outline_Funcs class_ =       \
          {                                            \
            move_to_,                                  \
            line_to_,                                  \
            conic_to_,                                 \
            cubic_to_,                                 \
            shift_,                                    \
            delta_                                     \
         };

#define SW_FT_DEFINE_RASTER_FUNCS( class_,                        \
                                raster_new_, raster_reset_,       \
                                raster_render_,                   \
                                raster_done_ )                    \
          const SW_FT_Raster_Funcs class_ =                       \
          {                                                       \
            raster_new_,                                          \
            raster_reset_,                                        \
            raster_render_,                                       \
            raster_done_                                          \
         };


#ifndef SW_FT_MEM_SET
#define SW_FT_MEM_SET( d, s, c )  ft_memset( d, s, c )
#endif

#ifndef SW_FT_MEM_ZERO
#define SW_FT_MEM_ZERO( dest, count )  SW_FT_MEM_SET( dest, 0, count )
#endif

  /* as usual, for the speed hungry :-) */

#undef RAS_ARG
#undef RAS_ARG_
#undef RAS_VAR
#undef RAS_VAR_

#ifndef SW_FT_STATIC_RASTER

#define RAS_ARG   gray_PWorker  worker
#define RAS_ARG_  gray_PWorker  worker,

#define RAS_VAR   worker
#define RAS_VAR_  worker,

#else /* SW_FT_STATIC_RASTER */

#define RAS_ARG   /* empty */
#define RAS_ARG_  /* empty */
#define RAS_VAR   /* empty */
#define RAS_VAR_  /* empty */

#endif /* SW_FT_STATIC_RASTER */


  /* must be at least 6 bits! */
#define PIXEL_BITS  8

#undef FLOOR
#undef CEILING
#undef TRUNC
#undef SCALED

#define ONE_PIXEL       ( 1L << PIXEL_BITS )
#define PIXEL_MASK      ( -1L << PIXEL_BITS )
#define TRUNC( x )      ( (TCoord)( (x) >> PIXEL_BITS ) )
#define SUBPIXELS( x )  ( (TPos)(x) << PIXEL_BITS )
#define FLOOR( x )      ( (x) & -ONE_PIXEL )
#define CEILING( x )    ( ( (x) + ONE_PIXEL - 1 ) & -ONE_PIXEL )
#define ROUND( x )      ( ( (x) + ONE_PIXEL / 2 ) & -ONE_PIXEL )

#if PIXEL_BITS >= 6
#define UPSCALE( x )    ( (x) << ( PIXEL_BITS - 6 ) )
#define DOWNSCALE( x )  ( (x) >> ( PIXEL_BITS - 6 ) )
#else
#define UPSCALE( x )    ( (x) >> ( 6 - PIXEL_BITS ) )
#define DOWNSCALE( x )  ( (x) << ( 6 - PIXEL_BITS ) )
#endif


  /* Compute `dividend / divisor' and return both its quotient and     */
  /* remainder, cast to a specific type.  This macro also ensures that */
  /* the remainder is always positive.                                 */
#define SW_FT_DIV_MOD( type, dividend, divisor, quotient, remainder ) \
  SW_FT_BEGIN_STMNT                                                   \
    (quotient)  = (type)( (dividend) / (divisor) );                \
    (remainder) = (type)( (dividend) % (divisor) );                \
    if ( (remainder) < 0 )                                         \
    {                                                              \
      (quotient)--;                                                \
      (remainder) += (type)(divisor);                              \
    }                                                              \
  SW_FT_END_STMNT

#ifdef  __arm__
  /* Work around a bug specific to GCC which make the compiler fail to */
  /* optimize a division and modulo operation on the same parameters   */
  /* into a single call to `__aeabi_idivmod'.  See                     */
  /*                                                                   */
  /*  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43721                */
#undef SW_FT_DIV_MOD
#define SW_FT_DIV_MOD( type, dividend, divisor, quotient, remainder ) \
  SW_FT_BEGIN_STMNT                                                   \
    (quotient)  = (type)( (dividend) / (divisor) );                \
    (remainder) = (type)( (dividend) - (quotient) * (divisor) );   \
    if ( (remainder) < 0 )                                         \
    {                                                              \
      (quotient)--;                                                \
      (remainder) += (type)(divisor);                              \
    }                                                              \
  SW_FT_END_STMNT
#endif /* __arm__ */

  /* These macros speed up repetitive divisions by replacing them */
  /* with multiplications and right shifts.                       */ 
#define SW_FT_UDIVPREP( b )                                       \
  long  b ## _r = (long)( SW_FT_ULONG_MAX >> PIXEL_BITS ) / ( b )
#define SW_FT_UDIV( a, b )                                        \
  ( ( (unsigned long)( a ) * (unsigned long)( b ## _r ) ) >>   \
    ( sizeof( long ) * SW_FT_CHAR_BIT - PIXEL_BITS ) )


  /*************************************************************************/
  /*                                                                       */
  /*   TYPE DEFINITIONS                                                    */
  /*                                                                       */

  /* don't change the following types to SW_FT_Int or SW_FT_Pos, since we might */
  /* need to define them to "float" or "double" when experimenting with   */
  /* new algorithms                                                       */

  typedef long  TCoord;   /* integer scanline/pixel coordinate */
  typedef long  TPos;     /* sub-pixel coordinate              */

  /* determine the type used to store cell areas.  This normally takes at */
  /* least PIXEL_BITS*2 + 1 bits.  On 16-bit systems, we need to use      */
  /* `long' instead of `int', otherwise bad things happen                 */

#if PIXEL_BITS <= 7

  typedef int  TArea;

#else /* PIXEL_BITS >= 8 */

  /* approximately determine the size of integers using an ANSI-C header */
#if SW_FT_UINT_MAX == 0xFFFFU
  typedef long  TArea;
#else
  typedef int   TArea;
#endif

#endif /* PIXEL_BITS >= 8 */


  /* maximum number of gray spans in a call to the span callback */
#define SW_FT_MAX_GRAY_SPANS  256


  typedef struct TCell_*  PCell;

  typedef struct  TCell_
  {
    TPos    x;     /* same with gray_TWorker.ex    */
    TCoord  cover; /* same with gray_TWorker.cover */
    TArea   area;
    PCell   next;

  } TCell;


#if defined( _MSC_VER )      /* Visual C++ (and Intel C++) */
  /* We disable the warning `structure was padded due to   */
  /* __declspec(align())' in order to compile cleanly with */
  /* the maximum level of warnings.                        */
#pragma warning( push )
#pragma warning( disable : 4324 )
#endif /* _MSC_VER */

  typedef struct  gray_TWorker_
  {
    TCoord  ex, ey;
    TPos    min_ex, max_ex;
    TPos    min_ey, max_ey;
    TPos    count_ex, count_ey;

    TArea   area;
    TCoord  cover;
    int     invalid;

    PCell       cells;
    SW_FT_PtrDist  max_cells;
    SW_FT_PtrDist  num_cells;

    TPos    x,  y;


    SW_FT_Vector   bez_stack[32 * 3 + 1];
    int         lev_stack[32];

    SW_FT_Outline  outline;
    SW_FT_BBox     clip_box;

    SW_FT_Span     gray_spans[SW_FT_MAX_GRAY_SPANS];
    int         num_gray_spans;

    SW_FT_Raster_Span_Func  render_span;
    void*                render_span_data;
    int                  span_y;

    int  band_size;
    int  band_shoot;

    ft_jmp_buf  jump_buffer;

    void*       buffer;
    long        buffer_size;

    PCell*     ycells;
    TPos       ycount;

  } gray_TWorker, *gray_PWorker;

#if defined( _MSC_VER )
#pragma warning( pop )
#endif


#ifndef SW_FT_STATIC_RASTER
#define ras  (*worker)
#else
  static gray_TWorker  ras;
#endif


  typedef struct gray_TRaster_
  {
    void*         memory;

  } gray_TRaster, *gray_PRaster;



  /*************************************************************************/
  /*                                                                       */
  /* Initialize the cells table.                                           */
  /*                                                                       */
  static void
  gray_init_cells( RAS_ARG_ void*  buffer,
                   long            byte_size )
  {
    ras.buffer      = buffer;
    ras.buffer_size = byte_size;

    ras.ycells      = (PCell*) buffer;
    ras.cells       = NULL;
    ras.max_cells   = 0;
    ras.num_cells   = 0;
    ras.area        = 0;
    ras.cover       = 0;
    ras.invalid     = 1;
  }


  /*************************************************************************/
  /*                                                                       */
  /* Compute the outline bounding box.                                     */
  /*                                                                       */
  static void
  gray_compute_cbox( RAS_ARG )
  {
    SW_FT_Outline*  outline = &ras.outline;
    SW_FT_Vector*   vec     = outline->points;
    SW_FT_Vector*   limit   = vec + outline->n_points;


    if ( outline->n_points <= 0 )
    {
      ras.min_ex = ras.max_ex = 0;
      ras.min_ey = ras.max_ey = 0;
      return;
    }

    ras.min_ex = ras.max_ex = vec->x;
    ras.min_ey = ras.max_ey = vec->y;

    vec++;

    for ( ; vec < limit; vec++ )
    {
      TPos  x = vec->x;
      TPos  y = vec->y;


      if ( x < ras.min_ex ) ras.min_ex = x;
      if ( x > ras.max_ex ) ras.max_ex = x;
      if ( y < ras.min_ey ) ras.min_ey = y;
      if ( y > ras.max_ey ) ras.max_ey = y;
    }

    /* truncate the bounding box to integer pixels */
    ras.min_ex = ras.min_ex >> 6;
    ras.min_ey = ras.min_ey >> 6;
    ras.max_ex = ( ras.max_ex + 63 ) >> 6;
    ras.max_ey = ( ras.max_ey + 63 ) >> 6;
  }


  /*************************************************************************/
  /*                                                                       */
  /* Record the current cell in the table.                                 */
  /*                                                                       */
  static PCell
  gray_find_cell( RAS_ARG )
  {
    PCell  *pcell, cell;
    TPos    x = ras.ex;


    if ( x > ras.count_ex )
      x = ras.count_ex;

    pcell = &ras.ycells[ras.ey];
    for (;;)
    {
      cell = *pcell;
      if ( cell == NULL || cell->x > x )
        break;

      if ( cell->x == x )
        goto Exit;

      pcell = &cell->next;
    }

    if ( ras.num_cells >= ras.max_cells )
      ft_longjmp( ras.jump_buffer, 1 );

    cell        = ras.cells + ras.num_cells++;
    cell->x     = x;
    cell->area  = 0;
    cell->cover = 0;

    cell->next  = *pcell;
    *pcell      = cell;

  Exit:
    return cell;
  }


  static void
  gray_record_cell( RAS_ARG )
  {
    if ( ras.area | ras.cover )
    {
      PCell  cell = gray_find_cell( RAS_VAR );


      cell->area  += ras.area;
      cell->cover += ras.cover;
    }
  }


  /*************************************************************************/
  /*                                                                       */
  /* Set the current cell to a new position.                               */
  /*                                                                       */
  static void
  gray_set_cell( RAS_ARG_ TCoord  ex,
                          TCoord  ey )
  {
    /* Move the cell pointer to a new position.  We set the `invalid'      */
    /* flag to indicate that the cell isn't part of those we're interested */
    /* in during the render phase.  This means that:                       */
    /*                                                                     */
    /* . the new vertical position must be within min_ey..max_ey-1.        */
    /* . the new horizontal position must be strictly less than max_ex     */
    /*                                                                     */
    /* Note that if a cell is to the left of the clipping region, it is    */
    /* actually set to the (min_ex-1) horizontal position.                 */

    /* All cells that are on the left of the clipping region go to the */
    /* min_ex - 1 horizontal position.                                 */
    ey -= ras.min_ey;

    if ( ex > ras.max_ex )
      ex = ras.max_ex;

    ex -= ras.min_ex;
    if ( ex < 0 )
      ex = -1;

    /* are we moving to a different cell ? */
    if ( ex != ras.ex || ey != ras.ey )
    {
      /* record the current one if it is valid */
      if ( !ras.invalid )
        gray_record_cell( RAS_VAR );

      ras.area  = 0;
      ras.cover = 0;
      ras.ex    = ex;
      ras.ey    = ey;
    }

    ras.invalid = ( (unsigned)ey >= (unsigned)ras.count_ey ||
                              ex >= ras.count_ex           );
  }


  /*************************************************************************/
  /*                                                                       */
  /* Start a new contour at a given cell.                                  */
  /*                                                                       */
  static void
  gray_start_cell( RAS_ARG_ TCoord  ex,
                            TCoord  ey )
  {
    if ( ex > ras.max_ex )
      ex = (TCoord)( ras.max_ex );

    if ( ex < ras.min_ex )
      ex = (TCoord)( ras.min_ex - 1 );

    ras.area    = 0;
    ras.cover   = 0;
    ras.ex      = ex - ras.min_ex;
    ras.ey      = ey - ras.min_ey;
    ras.invalid = 0;

    gray_set_cell( RAS_VAR_ ex, ey );
  }

  /*************************************************************************/
  /*                                                                       */
  /* Render a straight line across multiple cells in any direction.        */
  /*                                                                       */
  static void
  gray_render_line( RAS_ARG_ TPos  to_x,
                             TPos  to_y )
  {
    TPos    dx, dy, fx1, fy1, fx2, fy2;
    TCoord  ex1, ex2, ey1, ey2;


    ex1 = TRUNC( ras.x );
    ex2 = TRUNC( to_x );
    ey1 = TRUNC( ras.y );
    ey2 = TRUNC( to_y );

    /* perform vertical clipping */
    if ( ( ey1 >= ras.max_ey && ey2 >= ras.max_ey ) ||
         ( ey1 <  ras.min_ey && ey2 <  ras.min_ey ) )
      goto End;

    dx = to_x - ras.x;
    dy = to_y - ras.y;

    fx1 = ras.x - SUBPIXELS( ex1 );
    fy1 = ras.y - SUBPIXELS( ey1 );

    if ( ex1 == ex2 && ey1 == ey2 )       /* inside one cell */
      ;
    else if ( dy == 0 ) /* ex1 != ex2 */  /* any horizontal line */
    {
      ex1 = ex2;
      gray_set_cell( RAS_VAR_ ex1, ey1 );
    }
    else if ( dx == 0 )
    {
      if ( dy > 0 )                       /* vertical line up */
        do
        {
          fy2 = ONE_PIXEL;
          ras.cover += ( fy2 - fy1 );
          ras.area  += ( fy2 - fy1 ) * fx1 * 2;
          fy1 = 0;
          ey1++;
          gray_set_cell( RAS_VAR_ ex1, ey1 );
        } while ( ey1 != ey2 );
      else                                /* vertical line down */
        do
        {
          fy2 = 0;
          ras.cover += ( fy2 - fy1 );
          ras.area  += ( fy2 - fy1 ) * fx1 * 2;
          fy1 = ONE_PIXEL;
          ey1--;
          gray_set_cell( RAS_VAR_ ex1, ey1 );
        } while ( ey1 != ey2 );
    }
    else                                  /* any other line */
    {
      TArea  prod = dx * fy1 - dy * fx1;
      SW_FT_UDIVPREP( dx );
      SW_FT_UDIVPREP( dy );


      /* The fundamental value `prod' determines which side and the  */
      /* exact coordinate where the line exits current cell.  It is  */
      /* also easily updated when moving from one cell to the next.  */
      do
      {
        if      ( prod                                   <= 0 &&
                  prod - dx * ONE_PIXEL                  >  0 ) /* left */
        {
          fx2 = 0;
          fy2 = (TPos)SW_FT_UDIV( -prod, -dx );
          prod -= dy * ONE_PIXEL;
          ras.cover += ( fy2 - fy1 );
          ras.area  += ( fy2 - fy1 ) * ( fx1 + fx2 );
          fx1 = ONE_PIXEL;
          fy1 = fy2;
          ex1--;
        }
        else if ( prod - dx * ONE_PIXEL                  <= 0 &&
                  prod - dx * ONE_PIXEL + dy * ONE_PIXEL >  0 ) /* up */
        {
          prod -= dx * ONE_PIXEL;
          fx2 = (TPos)SW_FT_UDIV( -prod, dy );
          fy2 = ONE_PIXEL;
          ras.cover += ( fy2 - fy1 );
          ras.area  += ( fy2 - fy1 ) * ( fx1 + fx2 );
          fx1 = fx2;
          fy1 = 0;
          ey1++;
        }
        else if ( prod - dx * ONE_PIXEL + dy * ONE_PIXEL <= 0 &&
                  prod                  + dy * ONE_PIXEL >= 0 ) /* right */
        {
          prod += dy * ONE_PIXEL;
          fx2 = ONE_PIXEL;
          fy2 = (TPos)SW_FT_UDIV( prod, dx );
          ras.cover += ( fy2 - fy1 );
          ras.area  += ( fy2 - fy1 ) * ( fx1 + fx2 );
          fx1 = 0;
          fy1 = fy2;
          ex1++;
        }
        else /* ( prod                  + dy * ONE_PIXEL <  0 &&
                  prod                                   >  0 )    down */
        {
          fx2 = (TPos)SW_FT_UDIV( prod, -dy );
          fy2 = 0;
          prod += dx * ONE_PIXEL;
          ras.cover += ( fy2 - fy1 );
          ras.area  += ( fy2 - fy1 ) * ( fx1 + fx2 );
          fx1 = fx2;
          fy1 = ONE_PIXEL;
          ey1--;
        }

        gray_set_cell( RAS_VAR_ ex1, ey1 );
      } while ( ex1 != ex2 || ey1 != ey2 );
    }

    fx2 = to_x - SUBPIXELS( ex2 );
    fy2 = to_y - SUBPIXELS( ey2 );

    ras.cover += ( fy2 - fy1 );
    ras.area  += ( fy2 - fy1 ) * ( fx1 + fx2 );

  End:
    ras.x       = to_x;
    ras.y       = to_y;
  }

  static void
  gray_split_conic( SW_FT_Vector*  base )
  {
    TPos  a, b;


    base[4].x = base[2].x;
    b = base[1].x;
    a = base[3].x = ( base[2].x + b ) / 2;
    b = base[1].x = ( base[0].x + b ) / 2;
    base[2].x = ( a + b ) / 2;

    base[4].y = base[2].y;
    b = base[1].y;
    a = base[3].y = ( base[2].y + b ) / 2;
    b = base[1].y = ( base[0].y + b ) / 2;
    base[2].y = ( a + b ) / 2;
  }


  static void
  gray_render_conic( RAS_ARG_ const SW_FT_Vector*  control,
                              const SW_FT_Vector*  to )
  {
    TPos        dx, dy;
    TPos        min, max, y;
    int         top, level;
    int*        levels;
    SW_FT_Vector*  arc;


    levels = ras.lev_stack;

    arc      = ras.bez_stack;
    arc[0].x = UPSCALE( to->x );
    arc[0].y = UPSCALE( to->y );
    arc[1].x = UPSCALE( control->x );
    arc[1].y = UPSCALE( control->y );
    arc[2].x = ras.x;
    arc[2].y = ras.y;
    top      = 0;

    dx = SW_FT_ABS( arc[2].x + arc[0].x - 2 * arc[1].x );
    dy = SW_FT_ABS( arc[2].y + arc[0].y - 2 * arc[1].y );
    if ( dx < dy )
      dx = dy;

    if ( dx < ONE_PIXEL / 4 )
      goto Draw;

    /* short-cut the arc that crosses the current band */
    min = max = arc[0].y;

    y = arc[1].y;
    if ( y < min ) min = y;
    if ( y > max ) max = y;

    y = arc[2].y;
    if ( y < min ) min = y;
    if ( y > max ) max = y;

    if ( TRUNC( min ) >= ras.max_ey || TRUNC( max ) < ras.min_ey )
      goto Draw;

    level = 0;
    do
    {
      dx >>= 2;
      level++;
    } while ( dx > ONE_PIXEL / 4 );

    levels[0] = level;

    do
    {
      level = levels[top];
      if ( level > 0 )
      {
        gray_split_conic( arc );
        arc += 2;
        top++;
        levels[top] = levels[top - 1] = level - 1;
        continue;
      }

    Draw:
      gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );
      top--;
      arc -= 2;

    } while ( top >= 0 );
  }


  static void
  gray_split_cubic( SW_FT_Vector*  base )
  {
    TPos  a, b, c, d;


    base[6].x = base[3].x;
    c = base[1].x;
    d = base[2].x;
    base[1].x = a = ( base[0].x + c ) / 2;
    base[5].x = b = ( base[3].x + d ) / 2;
    c = ( c + d ) / 2;
    base[2].x = a = ( a + c ) / 2;
    base[4].x = b = ( b + c ) / 2;
    base[3].x = ( a + b ) / 2;

    base[6].y = base[3].y;
    c = base[1].y;
    d = base[2].y;
    base[1].y = a = ( base[0].y + c ) / 2;
    base[5].y = b = ( base[3].y + d ) / 2;
    c = ( c + d ) / 2;
    base[2].y = a = ( a + c ) / 2;
    base[4].y = b = ( b + c ) / 2;
    base[3].y = ( a + b ) / 2;
  }


  static void
  gray_render_cubic( RAS_ARG_ const SW_FT_Vector*  control1,
                              const SW_FT_Vector*  control2,
                              const SW_FT_Vector*  to )
  {
    SW_FT_Vector*  arc;
    TPos        min, max, y;


    arc      = ras.bez_stack;
    arc[0].x = UPSCALE( to->x );
    arc[0].y = UPSCALE( to->y );
    arc[1].x = UPSCALE( control2->x );
    arc[1].y = UPSCALE( control2->y );
    arc[2].x = UPSCALE( control1->x );
    arc[2].y = UPSCALE( control1->y );
    arc[3].x = ras.x;
    arc[3].y = ras.y;

    /* Short-cut the arc that crosses the current band. */
    min = max = arc[0].y;

    y = arc[1].y;
    if ( y < min )
      min = y;
    if ( y > max )
      max = y;

    y = arc[2].y;
    if ( y < min )
      min = y;
    if ( y > max )
      max = y;

    y = arc[3].y;
    if ( y < min )
      min = y;
    if ( y > max )
      max = y;

    if ( TRUNC( min ) >= ras.max_ey || TRUNC( max ) < ras.min_ey )
      goto Draw;

    for (;;)
    {
      /* Decide whether to split or draw. See `Rapid Termination          */
      /* Evaluation for Recursive Subdivision of Bezier Curves' by Thomas */
      /* F. Hain, at                                                      */
      /* http://www.cis.southalabama.edu/~hain/general/Publications/Bezier/Camera-ready%20CISST02%202.pdf */

      {
        TPos  dx, dy, dx_, dy_;
        TPos  dx1, dy1, dx2, dy2;
        TPos  L, s, s_limit;


        /* dx and dy are x and y components of the P0-P3 chord vector. */
        dx = dx_ = arc[3].x - arc[0].x;
        dy = dy_ = arc[3].y - arc[0].y;

        L = SW_FT_HYPOT( dx_, dy_ );

        /* Avoid possible arithmetic overflow below by splitting. */
        if ( L > 32767 )
          goto Split;

        /* Max deviation may be as much as (s/L) * 3/4 (if Hain's v = 1). */
        s_limit = L * (TPos)( ONE_PIXEL / 6 );

        /* s is L * the perpendicular distance from P1 to the line P0-P3. */
        dx1 = arc[1].x - arc[0].x;
        dy1 = arc[1].y - arc[0].y;
        s = SW_FT_ABS( dy * dx1 - dx * dy1 );

        if ( s > s_limit )
          goto Split;

        /* s is L * the perpendicular distance from P2 to the line P0-P3. */
        dx2 = arc[2].x - arc[0].x;
        dy2 = arc[2].y - arc[0].y;
        s = SW_FT_ABS( dy * dx2 - dx * dy2 );

        if ( s > s_limit )
          goto Split;

        /* Split super curvy segments where the off points are so far
           from the chord that the angles P0-P1-P3 or P0-P2-P3 become
           acute as detected by appropriate dot products. */
        if ( dx1 * ( dx1 - dx ) + dy1 * ( dy1 - dy ) > 0 ||
             dx2 * ( dx2 - dx ) + dy2 * ( dy2 - dy ) > 0 )
          goto Split;

        /* No reason to split. */
        goto Draw;
      }

    Split:
      gray_split_cubic( arc );
      arc += 3;
      continue;

    Draw:
      gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );

      if ( arc == ras.bez_stack )
        return;

      arc -= 3;
    }
  }


  static int
  gray_move_to( const SW_FT_Vector*  to,
                gray_PWorker      worker )
  {
    TPos  x, y;


    /* record current cell, if any */
    if ( !ras.invalid )
      gray_record_cell( RAS_VAR );

    /* start to a new position */
    x = UPSCALE( to->x );
    y = UPSCALE( to->y );

    gray_start_cell( RAS_VAR_ TRUNC( x ), TRUNC( y ) );

    worker->x = x;
    worker->y = y;
    return 0;
  }


  static int
  gray_line_to( const SW_FT_Vector*  to,
                gray_PWorker      worker )
  {
    gray_render_line( RAS_VAR_ UPSCALE( to->x ), UPSCALE( to->y ) );
    return 0;
  }


  static int
  gray_conic_to( const SW_FT_Vector*  control,
                 const SW_FT_Vector*  to,
                 gray_PWorker      worker )
  {
    gray_render_conic( RAS_VAR_ control, to );
    return 0;
  }


  static int
  gray_cubic_to( const SW_FT_Vector*  control1,
                 const SW_FT_Vector*  control2,
                 const SW_FT_Vector*  to,
                 gray_PWorker      worker )
  {
    gray_render_cubic( RAS_VAR_ control1, control2, to );
    return 0;
  }


  static void
  gray_hline( RAS_ARG_ TCoord  x,
                       TCoord  y,
                       TPos    area,
                       TCoord  acount )
  {
    int  coverage;


    /* compute the coverage line's coverage, depending on the    */
    /* outline fill rule                                         */
    /*                                                           */
    /* the coverage percentage is area/(PIXEL_BITS*PIXEL_BITS*2) */
    /*                                                           */
    coverage = (int)( area >> ( PIXEL_BITS * 2 + 1 - 8 ) );
                                                    /* use range 0..256 */
    if ( coverage < 0 )
      coverage = -coverage;

    if ( ras.outline.flags & SW_FT_OUTLINE_EVEN_ODD_FILL )
    {
      coverage &= 511;

      if ( coverage > 256 )
        coverage = 512 - coverage;
      else if ( coverage == 256 )
        coverage = 255;
    }
    else
    {
      /* normal non-zero winding rule */
      if ( coverage >= 256 )
        coverage = 255;
    }

    y += (TCoord)ras.min_ey;
    x += (TCoord)ras.min_ex;

    /* SW_FT_Span.x is a 16-bit short, so limit our coordinates appropriately */
    if ( x >= 32767 )
      x = 32767;

    /* SW_FT_Span.y is an integer, so limit our coordinates appropriately */
    if ( y >= SW_FT_INT_MAX )
      y = SW_FT_INT_MAX;

    if ( coverage )
    {
      SW_FT_Span*  span;
      int       count;


      /* see whether we can add this span to the current list */
      count = ras.num_gray_spans;
      span  = ras.gray_spans + count - 1;
      if ( count > 0                          &&
           ras.span_y == y                    &&
           (int)span->x + span->len == (int)x &&
           span->coverage == coverage         )
      {
        span->len = (unsigned short)( span->len + acount );
        return;
      }

      if ( count >= SW_FT_MAX_GRAY_SPANS )
      {
        if ( ras.render_span && count > 0 )
          ras.render_span(count, ras.gray_spans,
                           ras.render_span_data );

        #ifdef DEBUG_GRAYS

                if ( 1 )
                {
                  int  n;


                  fprintf( stderr, "count = %3d ", count );
                  span = ras.gray_spans;
                  for ( n = 0; n < count; n++, span++ )
                    fprintf( stderr, "[%d , %d..%d] : %d ",
                             span->y, span->x, span->x + span->len - 1, span->coverage );
                  fprintf( stderr, "\n" );
                }

        #endif /* DEBUG_GRAYS */

        ras.num_gray_spans = 0;
        //ras.span_y         = (int)y;

        span  = ras.gray_spans;
      }
      else
        span++;

      /* add a gray span to the current list */
      span->x        = (short)x;
      span->y        = (short)y;
      span->len      = (unsigned short)acount;
      span->coverage = (unsigned char)coverage;

      ras.num_gray_spans++;
    }
  }

  static void
  gray_sweep( RAS_ARG)
  {
    int  yindex;

    if ( ras.num_cells == 0 )
      return;

    ras.num_gray_spans = 0;

    for ( yindex = 0; yindex < ras.ycount; yindex++ )
    {
      PCell   cell  = ras.ycells[yindex];
      TCoord  cover = 0;
      TCoord  x     = 0;


      for ( ; cell != NULL; cell = cell->next )
      {
        TPos  area;


        if ( cell->x > x && cover != 0 )
          gray_hline( RAS_VAR_ x, yindex, cover * ( ONE_PIXEL * 2 ),
                      cell->x - x );

        cover += cell->cover;
        area   = cover * ( ONE_PIXEL * 2 ) - cell->area;

        if ( area != 0 && cell->x >= 0 )
          gray_hline( RAS_VAR_ cell->x, yindex, area, 1 );

        x = cell->x + 1;
      }

      if ( cover != 0 )
        gray_hline( RAS_VAR_ x, yindex, cover * ( ONE_PIXEL * 2 ),
                    ras.count_ex - x );
    }

    if ( ras.render_span && ras.num_gray_spans > 0 )
      ras.render_span(ras.num_gray_spans,
                       ras.gray_spans, ras.render_span_data );
  }


  /*************************************************************************/
  /*                                                                       */
  /*  The following function should only compile in stand-alone mode,      */
  /*  i.e., when building this component without the rest of FreeType.     */
  /*                                                                       */
  /*************************************************************************/

  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    SW_FT_Outline_Decompose                                               */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Walk over an outline's structure to decompose it into individual   */
  /*    segments and B├ęzier arcs.  This function is also able to emit      */
  /*    `move to' and `close to' operations to indicate the start and end  */
  /*    of new contours in the outline.                                    */
  /*                                                                       */
  /* <Input>                                                               */
  /*    outline        :: A pointer to the source target.                  */
  /*                                                                       */
  /*    func_interface :: A table of `emitters', i.e., function pointers   */
  /*                      called during decomposition to indicate path     */
  /*                      operations.                                      */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    user           :: A typeless pointer which is passed to each       */
  /*                      emitter during the decomposition.  It can be     */
  /*                      used to store the state during the               */
  /*                      decomposition.                                   */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Error code.  0 means success.                                      */
  /*                                                                       */
  static int
  SW_FT_Outline_Decompose( const SW_FT_Outline*        outline,
                        const SW_FT_Outline_Funcs*  func_interface,
                        void*                    user )
  {
#undef SCALED
#define SCALED( x )  ( ( (x) << shift ) - delta )

    SW_FT_Vector   v_last;
    SW_FT_Vector   v_control;
    SW_FT_Vector   v_start;

    SW_FT_Vector*  point;
    SW_FT_Vector*  limit;
    char*       tags;

    int         error;

    int   n;         /* index of contour in outline     */
    int   first;     /* index of first point in contour */
    char  tag;       /* current point's state           */

    int   shift;
    TPos  delta;


    if ( !outline || !func_interface )
      return SW_FT_THROW( Invalid_Argument );

    shift = func_interface->shift;
    delta = func_interface->delta;
    first = 0;

    for ( n = 0; n < outline->n_contours; n++ )
    {
      int  last;  /* index of last point in contour */


      last  = outline->contours[n];
      if ( last < 0 )
        goto Invalid_Outline;
      limit = outline->points + last;

      v_start   = outline->points[first];
      v_start.x = SCALED( v_start.x );
      v_start.y = SCALED( v_start.y );

      v_last   = outline->points[last];
      v_last.x = SCALED( v_last.x );
      v_last.y = SCALED( v_last.y );

      v_control = v_start;

      point = outline->points + first;
      tags  = outline->tags   + first;
      tag   = SW_FT_CURVE_TAG( tags[0] );

      /* A contour cannot start with a cubic control point! */
      if ( tag == SW_FT_CURVE_TAG_CUBIC )
        goto Invalid_Outline;

      /* check first point to determine origin */
      if ( tag == SW_FT_CURVE_TAG_CONIC )
      {
        /* first point is conic control.  Yes, this happens. */
        if ( SW_FT_CURVE_TAG( outline->tags[last] ) == SW_FT_CURVE_TAG_ON )
        {
          /* start at last point if it is on the curve */
          v_start = v_last;
          limit--;
        }
        else
        {
          /* if both first and last points are conic,         */
          /* start at their middle and record its position    */
          /* for closure                                      */
          v_start.x = ( v_start.x + v_last.x ) / 2;
          v_start.y = ( v_start.y + v_last.y ) / 2;

          v_last = v_start;
        }
        point--;
        tags--;
      }

      error = func_interface->move_to( &v_start, user );
      if ( error )
        goto Exit;

      while ( point < limit )
      {
        point++;
        tags++;

        tag = SW_FT_CURVE_TAG( tags[0] );
        switch ( tag )
        {
        case SW_FT_CURVE_TAG_ON:  /* emit a single line_to */
          {
            SW_FT_Vector  vec;


            vec.x = SCALED( point->x );
            vec.y = SCALED( point->y );

            error = func_interface->line_to( &vec, user );
            if ( error )
              goto Exit;
            continue;
          }

        case SW_FT_CURVE_TAG_CONIC:  /* consume conic arcs */
          v_control.x = SCALED( point->x );
          v_control.y = SCALED( point->y );

        Do_Conic:
          if ( point < limit )
          {
            SW_FT_Vector  vec;
            SW_FT_Vector  v_middle;


            point++;
            tags++;
            tag = SW_FT_CURVE_TAG( tags[0] );

            vec.x = SCALED( point->x );
            vec.y = SCALED( point->y );

            if ( tag == SW_FT_CURVE_TAG_ON )
            {
              error = func_interface->conic_to( &v_control, &vec, user );
              if ( error )
                goto Exit;
              continue;
            }

            if ( tag != SW_FT_CURVE_TAG_CONIC )
              goto Invalid_Outline;

            v_middle.x = ( v_control.x + vec.x ) / 2;
            v_middle.y = ( v_control.y + vec.y ) / 2;

            error = func_interface->conic_to( &v_control, &v_middle, user );
            if ( error )
              goto Exit;

            v_control = vec;
            goto Do_Conic;
          }

          error = func_interface->conic_to( &v_control, &v_start, user );
          goto Close;

        default:  /* SW_FT_CURVE_TAG_CUBIC */
          {
            SW_FT_Vector  vec1, vec2;


            if ( point + 1 > limit                             ||
                 SW_FT_CURVE_TAG( tags[1] ) != SW_FT_CURVE_TAG_CUBIC )
              goto Invalid_Outline;

            point += 2;
            tags  += 2;

            vec1.x = SCALED( point[-2].x );
            vec1.y = SCALED( point[-2].y );

            vec2.x = SCALED( point[-1].x );
            vec2.y = SCALED( point[-1].y );

            if ( point <= limit )
            {
              SW_FT_Vector  vec;


              vec.x = SCALED( point->x );
              vec.y = SCALED( point->y );

              error = func_interface->cubic_to( &vec1, &vec2, &vec, user );
              if ( error )
                goto Exit;
              continue;
            }

            error = func_interface->cubic_to( &vec1, &vec2, &v_start, user );
            goto Close;
          }
        }
      }

      /* close the contour with a line segment */
      error = func_interface->line_to( &v_start, user );

   Close:
      if ( error )
        goto Exit;

      first = last + 1;
    }

    return 0;

  Exit:
    return error;

  Invalid_Outline:
    return SW_FT_THROW( Invalid_Outline );
  }


  typedef struct  gray_TBand_
  {
    TPos  min, max;

  } gray_TBand;



  SW_FT_DEFINE_OUTLINE_FUNCS(func_interface,
      (SW_FT_Outline_MoveTo_Func) gray_move_to,
      (SW_FT_Outline_LineTo_Func) gray_line_to,
      (SW_FT_Outline_ConicTo_Func)gray_conic_to,
      (SW_FT_Outline_CubicTo_Func)gray_cubic_to,
      0,
      0
    )

  static int
  gray_convert_glyph_inner( RAS_ARG )
  {

    volatile int  error = 0;

    if ( ft_setjmp( ras.jump_buffer ) == 0 )
    {
      error = SW_FT_Outline_Decompose( &ras.outline, &func_interface, &ras );
      if ( !ras.invalid )
        gray_record_cell( RAS_VAR );
    }
    else
      error = SW_FT_THROW( Memory_Overflow );

    return error;
  }


  static int
  gray_convert_glyph( RAS_ARG )
  {
    gray_TBand            bands[40];
    gray_TBand* volatile  band;
    int volatile          n, num_bands;
    TPos volatile         min, max, max_y;
    SW_FT_BBox*              clip;


    /* Set up state in the raster object */
    gray_compute_cbox( RAS_VAR );

    /* clip to target bitmap, exit if nothing to do */
    clip = &ras.clip_box;

    if ( ras.max_ex <= clip->xMin || ras.min_ex >= clip->xMax ||
         ras.max_ey <= clip->yMin || ras.min_ey >= clip->yMax )
      return 0;

    if ( ras.min_ex < clip->xMin ) ras.min_ex = clip->xMin;
    if ( ras.min_ey < clip->yMin ) ras.min_ey = clip->yMin;

    if ( ras.max_ex > clip->xMax ) ras.max_ex = clip->xMax;
    if ( ras.max_ey > clip->yMax ) ras.max_ey = clip->yMax;

    ras.count_ex = ras.max_ex - ras.min_ex;
    ras.count_ey = ras.max_ey - ras.min_ey;

    /* set up vertical bands */
    num_bands = (int)( ( ras.max_ey - ras.min_ey ) / ras.band_size );
    if ( num_bands == 0 )
      num_bands = 1;
    if ( num_bands >= 39 )
      num_bands = 39;

    ras.band_shoot = 0;

    min   = ras.min_ey;
    max_y = ras.max_ey;

    for ( n = 0; n < num_bands; n++, min = max )
    {
      max = min + ras.band_size;
      if ( n == num_bands - 1 || max > max_y )
        max = max_y;

      bands[0].min = min;
      bands[0].max = max;
      band         = bands;

      while ( band >= bands )
      {
        TPos  bottom, top, middle;
        int   error;

        {
          PCell  cells_max;
          int    yindex;
          long   cell_start, cell_end, cell_mod;


          ras.ycells = (PCell*)ras.buffer;
          ras.ycount = band->max - band->min;

          cell_start = sizeof ( PCell ) * ras.ycount;
          cell_mod   = cell_start % sizeof ( TCell );
          if ( cell_mod > 0 )
            cell_start += sizeof ( TCell ) - cell_mod;

          cell_end  = ras.buffer_size;
          cell_end -= cell_end % sizeof ( TCell );

          cells_max = (PCell)( (char*)ras.buffer + cell_end );
          ras.cells = (PCell)( (char*)ras.buffer + cell_start );
          if ( ras.cells >= cells_max )
            goto ReduceBands;

          ras.max_cells = cells_max - ras.cells;
          if ( ras.max_cells < 2 )
            goto ReduceBands;

          for ( yindex = 0; yindex < ras.ycount; yindex++ )
            ras.ycells[yindex] = NULL;
        }

        ras.num_cells = 0;
        ras.invalid   = 1;
        ras.min_ey    = band->min;
        ras.max_ey    = band->max;
        ras.count_ey  = band->max - band->min;

        error = gray_convert_glyph_inner( RAS_VAR );

        if ( !error )
        {
          gray_sweep( RAS_VAR);
          band--;
          continue;
        }
        else if ( error != ErrRaster_Memory_Overflow )
          return 1;

      ReduceBands:
        /* render pool overflow; we will reduce the render band by half */
        bottom = band->min;
        top    = band->max;
        middle = bottom + ( ( top - bottom ) >> 1 );

        /* This is too complex for a single scanline; there must */
        /* be some problems.                                     */
        if ( middle == bottom )
        {
          return 1;
        }

        if ( bottom-top >= ras.band_size )
          ras.band_shoot++;

        band[1].min = bottom;
        band[1].max = middle;
        band[0].min = middle;
        band[0].max = top;
        band++;
      }
    }

    if ( ras.band_shoot > 8 && ras.band_size > 16 )
      ras.band_size = ras.band_size / 2;

    return 0;
  }

  static int
  gray_raster_render( gray_PRaster             raster,
                      const SW_FT_Raster_Params*  params )
  {
    const SW_FT_Outline*  outline     = (const SW_FT_Outline*)params->source;

    gray_TWorker  worker[1];

    TCell  buffer[SW_FT_RENDER_POOL_SIZE / sizeof ( TCell )];
    long   buffer_size = sizeof ( buffer );
    int    band_size   = (int)( buffer_size /
                                (long)( sizeof ( TCell ) * 8 ) );

    if ( !raster)
      return SW_FT_THROW( Invalid_Argument );

    if ( !outline )
      return SW_FT_THROW( Invalid_Outline );

    /* return immediately if the outline is empty */
    if ( outline->n_points == 0 || outline->n_contours <= 0 )
      return 0;

    if ( !outline->contours || !outline->points )
      return SW_FT_THROW( Invalid_Outline );

    if ( outline->n_points !=
           outline->contours[outline->n_contours - 1] + 1 )
      return SW_FT_THROW( Invalid_Outline );

    /* this version does not support monochrome rendering */
    if ( !( params->flags & SW_FT_RASTER_FLAG_AA ) )
      return SW_FT_THROW( Invalid_Mode );

    if ( params->flags & SW_FT_RASTER_FLAG_CLIP )
      ras.clip_box = params->clip_box;
    else
    {
      ras.clip_box.xMin = -32768L;
      ras.clip_box.yMin = -32768L;
      ras.clip_box.xMax =  32767L;
      ras.clip_box.yMax =  32767L;
    }

    gray_init_cells( RAS_VAR_ buffer, buffer_size );

    ras.outline        = *outline;
    ras.num_cells      = 0;
    ras.invalid        = 1;
    ras.band_size      = band_size;
    ras.num_gray_spans = 0;
    ras.span_y         = 0;

    ras.render_span      = (SW_FT_Raster_Span_Func)params->gray_spans;
    ras.render_span_data = params->user;

    return gray_convert_glyph( RAS_VAR );
  }

  /**** RASTER OBJECT CREATION: In stand-alone mode, we simply use *****/
  /****                         a static object.                   *****/

  static int
  gray_raster_new(SW_FT_Raster*  araster )
  {
    static gray_TRaster  the_raster;

    *araster = (SW_FT_Raster)&the_raster;
    SW_FT_MEM_ZERO( &the_raster, sizeof ( the_raster ) );

    return 0;
  }


  static void
  gray_raster_done( SW_FT_Raster  raster )
  {
    /* nothing */
    SW_FT_UNUSED( raster );
  }

  static void
  gray_raster_reset( SW_FT_Raster  raster,
                     char*      pool_base,
                     long       pool_size )
  {
    SW_FT_UNUSED( raster );
    SW_FT_UNUSED( pool_base );
    SW_FT_UNUSED( pool_size );
  }


  SW_FT_DEFINE_RASTER_FUNCS(sw_ft_grays_raster,

    (SW_FT_Raster_New_Func)     gray_raster_new,
    (SW_FT_Raster_Reset_Func)   gray_raster_reset,
    (SW_FT_Raster_Render_Func)  gray_raster_render,
    (SW_FT_Raster_Done_Func)    gray_raster_done
  )


/* END */