/***************************************************************************/
/*                                                                         */
/*  ftraster.c                                                             */
/*                                                                         */
/*    The FreeType glyph rasterizer (body).                                */
/*                                                                         */
/*  Copyright 1996-2003, 2005, 2007-2012 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 can be compiled without the rest of the FreeType engine, by */
  /* defining the _STANDALONE_ macro when compiling it.  You also need to  */
  /* put the files `ftimage.h' and `ftmisc.h' into the $(incdir)           */
  /* directory.  Typically, you should do something like                   */
  /*                                                                       */
  /* - copy `src/raster/ftraster.c' (this file) to your current directory  */
  /*                                                                       */
  /* - copy `include/freetype/ftimage.h' and `src/raster/ftmisc.h'         */
  /*   to your current directory                                           */
  /*                                                                       */
  /* - compile `ftraster' with the _STANDALONE_ macro defined, as in       */
  /*                                                                       */
  /*     cc -c -D_STANDALONE_ ftraster.c                                   */
  /*                                                                       */
  /* The renderer can be initialized with a call to                        */
  /* `ft_standard_raster.raster_new'; a bitmap can be generated            */
  /* with a call to `ft_standard_raster.raster_render'.                    */
  /*                                                                       */
  /* See the comments and documentation in the file `ftimage.h' for more   */
  /* details on how the raster works.                                      */
  /*                                                                       */
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* This is a rewrite of the FreeType 1.x scan-line converter             */
  /*                                                                       */
  /*************************************************************************/

#ifdef _STANDALONE_

#define FT_CONFIG_STANDARD_LIBRARY_H  <stdlib.h>

#include <string.h>           /* for memset */

#include "ftmisc.h"
#include "ftimage.h"

#else /* !_STANDALONE_ */

#include <ft2build.h>
#include "ftraster.h"
#include FT_INTERNAL_CALC_H   /* for FT_MulDiv only */

#include "rastpic.h"

#endif /* !_STANDALONE_ */


  /*************************************************************************/
  /*                                                                       */
  /* A simple technical note on how the raster works                       */
  /* -----------------------------------------------                       */
  /*                                                                       */
  /*   Converting an outline into a bitmap is achieved in several steps:   */
  /*                                                                       */
  /*   1 - Decomposing the outline into successive `profiles'.  Each       */
  /*       profile is simply an array of scanline intersections on a given */
  /*       dimension.  A profile's main attributes are                     */
  /*                                                                       */
  /*       o its scanline position boundaries, i.e. `Ymin' and `Ymax'      */
  /*                                                                       */
  /*       o an array of intersection coordinates for each scanline        */
  /*         between `Ymin' and `Ymax'                                     */
  /*                                                                       */
  /*       o a direction, indicating whether it was built going `up' or    */
  /*         `down', as this is very important for filling rules           */
  /*                                                                       */
  /*       o its drop-out mode                                             */
  /*                                                                       */
  /*   2 - Sweeping the target map's scanlines in order to compute segment */
  /*       `spans' which are then filled.  Additionally, this pass         */
  /*       performs drop-out control.                                      */
  /*                                                                       */
  /*   The outline data is parsed during step 1 only.  The profiles are    */
  /*   built from the bottom of the render pool, used as a stack.  The     */
  /*   following graphics shows the profile list under construction:       */
  /*                                                                       */
  /*     __________________________________________________________ _ _    */
  /*    |         |                 |         |                 |          */
  /*    | profile | coordinates for | profile | coordinates for |-->       */
  /*    |    1    |  profile 1      |    2    |  profile 2      |-->       */
  /*    |_________|_________________|_________|_________________|__ _ _    */
  /*                                                                       */
  /*    ^                                                       ^          */
  /*    |                                                       |          */
  /* start of render pool                                      top         */
  /*                                                                       */
  /*   The top of the profile stack is kept in the `top' variable.         */
  /*                                                                       */
  /*   As you can see, a profile record is pushed on top of the render     */
  /*   pool, which is then followed by its coordinates/intersections.  If  */
  /*   a change of direction is detected in the outline, a new profile is  */
  /*   generated until the end of the outline.                             */
  /*                                                                       */
  /*   Note that when all profiles have been generated, the function       */
  /*   Finalize_Profile_Table() is used to record, for each profile, its   */
  /*   bottom-most scanline as well as the scanline above its upmost       */
  /*   boundary.  These positions are called `y-turns' because they (sort  */
  /*   of) correspond to local extrema.  They are stored in a sorted list  */
  /*   built from the top of the render pool as a downwards stack:         */
  /*                                                                       */
  /*      _ _ _______________________________________                      */
  /*                            |                    |                     */
  /*                         <--| sorted list of     |                     */
  /*                         <--|  extrema scanlines |                     */
  /*      _ _ __________________|____________________|                     */
  /*                                                                       */
  /*                            ^                    ^                     */
  /*                            |                    |                     */
  /*                         maxBuff           sizeBuff = end of pool      */
  /*                                                                       */
  /*   This list is later used during the sweep phase in order to          */
  /*   optimize performance (see technical note on the sweep below).       */
  /*                                                                       */
  /*   Of course, the raster detects whether the two stacks collide and    */
  /*   handles the situation properly.                                     */
  /*                                                                       */
  /*************************************************************************/


  /*************************************************************************/
  /*************************************************************************/
  /**                                                                     **/
  /**  CONFIGURATION MACROS                                               **/
  /**                                                                     **/
  /*************************************************************************/
  /*************************************************************************/

  /* define DEBUG_RASTER if you want to compile a debugging version */
/* #define DEBUG_RASTER */

  /* define FT_RASTER_OPTION_ANTI_ALIASING if you want to support */
  /* 5-levels anti-aliasing                                       */
/* #define FT_RASTER_OPTION_ANTI_ALIASING */

  /* The size of the two-lines intermediate bitmap used */
  /* for anti-aliasing, in bytes.                       */
#define RASTER_GRAY_LINES  2048


  /*************************************************************************/
  /*************************************************************************/
  /**                                                                     **/
  /**  OTHER MACROS (do not change)                                       **/
  /**                                                                     **/
  /*************************************************************************/
  /*************************************************************************/

  /*************************************************************************/
  /*                                                                       */
  /* 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_raster


#ifdef _STANDALONE_


  /* 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 FT_UNUSED( x )  (x) = (x)

  /* Disable the tracing mechanism for simplicity -- developers can      */
  /* activate it easily by redefining these two macros.                  */
#ifndef FT_ERROR
#define FT_ERROR( x )  do { } while ( 0 )     /* nothing */
#endif

#ifndef FT_TRACE
#define FT_TRACE( x )   do { } while ( 0 )    /* nothing */
#define FT_TRACE1( x )  do { } while ( 0 )    /* nothing */
#define FT_TRACE6( x )  do { } while ( 0 )    /* nothing */
#endif

#define Raster_Err_None          0
#define Raster_Err_Not_Ini      -1
#define Raster_Err_Overflow     -2
#define Raster_Err_Neg_Height   -3
#define Raster_Err_Invalid      -4
#define Raster_Err_Unsupported  -5

#define ft_memset  memset

#define FT_DEFINE_RASTER_FUNCS( class_, glyph_format_, raster_new_, \
                                raster_reset_, raster_set_mode_,    \
                                raster_render_, raster_done_ )      \
          const FT_Raster_Funcs class_ =                            \
          {                                                         \
            glyph_format_,                                          \
            raster_new_,                                            \
            raster_reset_,                                          \
            raster_set_mode_,                                       \
            raster_render_,                                         \
            raster_done_                                            \
         };

#else /* !_STANDALONE_ */


#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_DEBUG_H        /* for FT_TRACE() and FT_ERROR() */

#include "rasterrs.h"

#define Raster_Err_None         Raster_Err_Ok
#define Raster_Err_Not_Ini      Raster_Err_Raster_Uninitialized
#define Raster_Err_Overflow     Raster_Err_Raster_Overflow
#define Raster_Err_Neg_Height   Raster_Err_Raster_Negative_Height
#define Raster_Err_Invalid      Raster_Err_Invalid_Outline
#define Raster_Err_Unsupported  Raster_Err_Cannot_Render_Glyph


#endif /* !_STANDALONE_ */


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

#ifndef FT_MEM_ZERO
#define FT_MEM_ZERO( dest, count )  FT_MEM_SET( dest, 0, count )
#endif

  /* FMulDiv means `Fast MulDiv'; it is used in case where `b' is       */
  /* typically a small value and the result of a*b is known to fit into */
  /* 32 bits.                                                           */
#define FMulDiv( a, b, c )  ( (a) * (b) / (c) )

  /* On the other hand, SMulDiv means `Slow MulDiv', and is used typically */
  /* for clipping computations.  It simply uses the FT_MulDiv() function   */
  /* defined in `ftcalc.h'.                                                */
#define SMulDiv  FT_MulDiv

  /* The rasterizer is a very general purpose component; please leave */
  /* the following redefinitions there (you never know your target    */
  /* environment).                                                    */

#ifndef TRUE
#define TRUE   1
#endif

#ifndef FALSE
#define FALSE  0
#endif

#ifndef NULL
#define NULL  (void*)0
#endif

#ifndef SUCCESS
#define SUCCESS  0
#endif

#ifndef FAILURE
#define FAILURE  1
#endif


#define MaxBezier  32   /* The maximum number of stacked Bezier curves. */
                        /* Setting this constant to more than 32 is a   */
                        /* pure waste of space.                         */

#define Pixel_Bits  6   /* fractional bits of *input* coordinates */


  /*************************************************************************/
  /*************************************************************************/
  /**                                                                     **/
  /**  SIMPLE TYPE DECLARATIONS                                           **/
  /**                                                                     **/
  /*************************************************************************/
  /*************************************************************************/

  typedef int             Int;
  typedef unsigned int    UInt;
  typedef short           Short;
  typedef unsigned short  UShort, *PUShort;
  typedef long            Long, *PLong;

  typedef unsigned char   Byte, *PByte;
  typedef char            Bool;


  typedef union  Alignment_
  {
    long    l;
    void*   p;
    void  (*f)(void);

  } Alignment, *PAlignment;


  typedef struct  TPoint_
  {
    Long  x;
    Long  y;

  } TPoint;


  /* values for the `flags' bit field */
#define Flow_Up           0x8
#define Overshoot_Top     0x10
#define Overshoot_Bottom  0x20


  /* States of each line, arc, and profile */
  typedef enum  TStates_
  {
    Unknown_State,
    Ascending_State,
    Descending_State,
    Flat_State

  } TStates;


  typedef struct TProfile_  TProfile;
  typedef TProfile*         PProfile;

  struct  TProfile_
  {
    FT_F26Dot6  X;           /* current coordinate during sweep          */
    PProfile    link;        /* link to next profile (various purposes)  */
    PLong       offset;      /* start of profile's data in render pool   */
    unsigned    flags;       /* Bit 0-2: drop-out mode                   */
                             /* Bit 3: profile orientation (up/down)     */
                             /* Bit 4: is top profile?                   */
                             /* Bit 5: is bottom profile?                */
    long        height;      /* profile's height in scanlines            */
    long        start;       /* profile's starting scanline              */

    unsigned    countL;      /* number of lines to step before this      */
                             /* profile becomes drawable                 */

    PProfile    next;        /* next profile in same contour, used       */
                             /* during drop-out control                  */
  };

  typedef PProfile   TProfileList;
  typedef PProfile*  PProfileList;


  /* Simple record used to implement a stack of bands, required */
  /* by the sub-banding mechanism                               */
  typedef struct  black_TBand_
  {
    Short  y_min;   /* band's minimum */
    Short  y_max;   /* band's maximum */

  } black_TBand;


#define AlignProfileSize \
  ( ( sizeof ( TProfile ) + sizeof ( Alignment ) - 1 ) / sizeof ( long ) )


#undef RAS_ARG
#undef RAS_ARGS
#undef RAS_VAR
#undef RAS_VARS

#ifdef FT_STATIC_RASTER


#define RAS_ARGS       /* void */
#define RAS_ARG        /* void */

#define RAS_VARS       /* void */
#define RAS_VAR        /* void */

#define FT_UNUSED_RASTER  do { } while ( 0 )


#else /* !FT_STATIC_RASTER */


#define RAS_ARGS       black_PWorker  worker,
#define RAS_ARG        black_PWorker  worker

#define RAS_VARS       worker,
#define RAS_VAR        worker

#define FT_UNUSED_RASTER  FT_UNUSED( worker )


#endif /* !FT_STATIC_RASTER */


  typedef struct black_TWorker_  black_TWorker, *black_PWorker;


  /* prototypes used for sweep function dispatch */
  typedef void
  Function_Sweep_Init( RAS_ARGS Short*  min,
                                Short*  max );

  typedef void
  Function_Sweep_Span( RAS_ARGS Short       y,
                                FT_F26Dot6  x1,
                                FT_F26Dot6  x2,
                                PProfile    left,
                                PProfile    right );

  typedef void
  Function_Sweep_Step( RAS_ARG );


  /* NOTE: These operations are only valid on 2's complement processors */
#undef FLOOR
#undef CEILING
#undef TRUNC
#undef SCALED

#define FLOOR( x )    ( (x) & -ras.precision )
#define CEILING( x )  ( ( (x) + ras.precision - 1 ) & -ras.precision )
#define TRUNC( x )    ( (signed long)(x) >> ras.precision_bits )
#define FRAC( x )     ( (x) & ( ras.precision - 1 ) )
#define SCALED( x )   ( ( (x) << ras.scale_shift ) - ras.precision_half )

#define IS_BOTTOM_OVERSHOOT( x )  ( CEILING( x ) - x >= ras.precision_half )
#define IS_TOP_OVERSHOOT( x )     ( x - FLOOR( x ) >= ras.precision_half )

  /* The most used variables are positioned at the top of the structure. */
  /* Thus, their offset can be coded with less opcodes, resulting in a   */
  /* smaller executable.                                                 */

  struct  black_TWorker_
  {
    Int         precision_bits;     /* precision related variables         */
    Int         precision;
    Int         precision_half;
    Int         precision_shift;
    Int         precision_step;
    Int         precision_jitter;

    Int         scale_shift;        /* == precision_shift   for bitmaps    */
                                    /* == precision_shift+1 for pixmaps    */

    PLong       buff;               /* The profiles buffer                 */
    PLong       sizeBuff;           /* Render pool size                    */
    PLong       maxBuff;            /* Profiles buffer size                */
    PLong       top;                /* Current cursor in buffer            */

    FT_Error    error;

    Int         numTurns;           /* number of Y-turns in outline        */

    TPoint*     arc;                /* current Bezier arc pointer          */

    UShort      bWidth;             /* target bitmap width                 */
    PByte       bTarget;            /* target bitmap buffer                */
    PByte       gTarget;            /* target pixmap buffer                */

    Long        lastX, lastY;
    Long        minY, maxY;

    UShort      num_Profs;          /* current number of profiles          */

    Bool        fresh;              /* signals a fresh new profile which   */
                                    /* `start' field must be completed     */
    Bool        joint;              /* signals that the last arc ended     */
                                    /* exactly on a scanline.  Allows      */
                                    /* removal of doublets                 */
    PProfile    cProfile;           /* current profile                     */
    PProfile    fProfile;           /* head of linked list of profiles     */
    PProfile    gProfile;           /* contour's first profile in case     */
                                    /* of impact                           */

    TStates     state;              /* rendering state                     */

    FT_Bitmap   target;             /* description of target bit/pixmap    */
    FT_Outline  outline;

    Long        traceOfs;           /* current offset in target bitmap     */
    Long        traceG;             /* current offset in target pixmap     */

    Short       traceIncr;          /* sweep's increment in target bitmap  */

    Short       gray_min_x;         /* current min x during gray rendering */
    Short       gray_max_x;         /* current max x during gray rendering */

    /* dispatch variables */

    Function_Sweep_Init*  Proc_Sweep_Init;
    Function_Sweep_Span*  Proc_Sweep_Span;
    Function_Sweep_Span*  Proc_Sweep_Drop;
    Function_Sweep_Step*  Proc_Sweep_Step;

    Byte        dropOutControl;     /* current drop_out control method     */

    Bool        second_pass;        /* indicates whether a horizontal pass */
                                    /* should be performed to control      */
                                    /* drop-out accurately when calling    */
                                    /* Render_Glyph.  Note that there is   */
                                    /* no horizontal pass during gray      */
                                    /* rendering.                          */

    TPoint      arcs[3 * MaxBezier + 1]; /* The Bezier stack               */

    black_TBand  band_stack[16];    /* band stack used for sub-banding     */
    Int          band_top;          /* band stack top                      */

#ifdef FT_RASTER_OPTION_ANTI_ALIASING

    Byte*       grays;

    Byte        gray_lines[RASTER_GRAY_LINES];
                                /* Intermediate table used to render the   */
                                /* graylevels pixmaps.                     */
                                /* gray_lines is a buffer holding two      */
                                /* monochrome scanlines                    */

    Short       gray_width;     /* width in bytes of one monochrome        */
                                /* intermediate scanline of gray_lines.    */
                                /* Each gray pixel takes 2 bits long there */

                       /* The gray_lines must hold 2 lines, thus with size */
                       /* in bytes of at least `gray_width*2'.             */

#endif /* FT_RASTER_ANTI_ALIASING */

  };


  typedef struct  black_TRaster_
  {
    char*          buffer;
    long           buffer_size;
    void*          memory;
    black_PWorker  worker;
    Byte           grays[5];
    Short          gray_width;

  } black_TRaster, *black_PRaster;

#ifdef FT_STATIC_RASTER

  static black_TWorker  cur_ras;
#define ras  cur_ras

#else /* !FT_STATIC_RASTER */

#define ras  (*worker)

#endif /* !FT_STATIC_RASTER */


#ifdef FT_RASTER_OPTION_ANTI_ALIASING

  /* A lookup table used to quickly count set bits in four gray 2x2 */
  /* cells.  The values of the table have been produced with the    */
  /* following code:                                                */
  /*                                                                */
  /*   for ( i = 0; i < 256; i++ )                                  */
  /*   {                                                            */
  /*     l = 0;                                                     */
  /*     j = i;                                                     */
  /*                                                                */
  /*     for ( c = 0; c < 4; c++ )                                  */
  /*     {                                                          */
  /*       l <<= 4;                                                 */
  /*                                                                */
  /*       if ( j & 0x80 ) l++;                                     */
  /*       if ( j & 0x40 ) l++;                                     */
  /*                                                                */
  /*       j = ( j << 2 ) & 0xFF;                                   */
  /*     }                                                          */
  /*     printf( "0x%04X", l );                                     */
  /*   }                                                            */
  /*                                                                */

  static const short  count_table[256] =
  {
    0x0000, 0x0001, 0x0001, 0x0002, 0x0010, 0x0011, 0x0011, 0x0012,
    0x0010, 0x0011, 0x0011, 0x0012, 0x0020, 0x0021, 0x0021, 0x0022,
    0x0100, 0x0101, 0x0101, 0x0102, 0x0110, 0x0111, 0x0111, 0x0112,
    0x0110, 0x0111, 0x0111, 0x0112, 0x0120, 0x0121, 0x0121, 0x0122,
    0x0100, 0x0101, 0x0101, 0x0102, 0x0110, 0x0111, 0x0111, 0x0112,
    0x0110, 0x0111, 0x0111, 0x0112, 0x0120, 0x0121, 0x0121, 0x0122,
    0x0200, 0x0201, 0x0201, 0x0202, 0x0210, 0x0211, 0x0211, 0x0212,
    0x0210, 0x0211, 0x0211, 0x0212, 0x0220, 0x0221, 0x0221, 0x0222,
    0x1000, 0x1001, 0x1001, 0x1002, 0x1010, 0x1011, 0x1011, 0x1012,
    0x1010, 0x1011, 0x1011, 0x1012, 0x1020, 0x1021, 0x1021, 0x1022,
    0x1100, 0x1101, 0x1101, 0x1102, 0x1110, 0x1111, 0x1111, 0x1112,
    0x1110, 0x1111, 0x1111, 0x1112, 0x1120, 0x1121, 0x1121, 0x1122,
    0x1100, 0x1101, 0x1101, 0x1102, 0x1110, 0x1111, 0x1111, 0x1112,
    0x1110, 0x1111, 0x1111, 0x1112, 0x1120, 0x1121, 0x1121, 0x1122,
    0x1200, 0x1201, 0x1201, 0x1202, 0x1210, 0x1211, 0x1211, 0x1212,
    0x1210, 0x1211, 0x1211, 0x1212, 0x1220, 0x1221, 0x1221, 0x1222,
    0x1000, 0x1001, 0x1001, 0x1002, 0x1010, 0x1011, 0x1011, 0x1012,
    0x1010, 0x1011, 0x1011, 0x1012, 0x1020, 0x1021, 0x1021, 0x1022,
    0x1100, 0x1101, 0x1101, 0x1102, 0x1110, 0x1111, 0x1111, 0x1112,
    0x1110, 0x1111, 0x1111, 0x1112, 0x1120, 0x1121, 0x1121, 0x1122,
    0x1100, 0x1101, 0x1101, 0x1102, 0x1110, 0x1111, 0x1111, 0x1112,
    0x1110, 0x1111, 0x1111, 0x1112, 0x1120, 0x1121, 0x1121, 0x1122,
    0x1200, 0x1201, 0x1201, 0x1202, 0x1210, 0x1211, 0x1211, 0x1212,
    0x1210, 0x1211, 0x1211, 0x1212, 0x1220, 0x1221, 0x1221, 0x1222,
    0x2000, 0x2001, 0x2001, 0x2002, 0x2010, 0x2011, 0x2011, 0x2012,
    0x2010, 0x2011, 0x2011, 0x2012, 0x2020, 0x2021, 0x2021, 0x2022,
    0x2100, 0x2101, 0x2101, 0x2102, 0x2110, 0x2111, 0x2111, 0x2112,
    0x2110, 0x2111, 0x2111, 0x2112, 0x2120, 0x2121, 0x2121, 0x2122,
    0x2100, 0x2101, 0x2101, 0x2102, 0x2110, 0x2111, 0x2111, 0x2112,
    0x2110, 0x2111, 0x2111, 0x2112, 0x2120, 0x2121, 0x2121, 0x2122,
    0x2200, 0x2201, 0x2201, 0x2202, 0x2210, 0x2211, 0x2211, 0x2212,
    0x2210, 0x2211, 0x2211, 0x2212, 0x2220, 0x2221, 0x2221, 0x2222
  };

#endif /* FT_RASTER_OPTION_ANTI_ALIASING */



  /*************************************************************************/
  /*************************************************************************/
  /**                                                                     **/
  /**  PROFILES COMPUTATION                                               **/
  /**                                                                     **/
  /*************************************************************************/
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Set_High_Precision                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Set precision variables according to param flag.                   */
  /*                                                                       */
  /* <Input>                                                               */
  /*    High :: Set to True for high precision (typically for ppem < 18),  */
  /*            false otherwise.                                           */
  /*                                                                       */
  static void
  Set_High_Precision( RAS_ARGS Int  High )
  {
    /*
     * `precision_step' is used in `Bezier_Up' to decide when to split a
     * given y-monotonous Bezier arc that crosses a scanline before
     * approximating it as a straight segment.  The default value of 32 (for
     * low accuracy) corresponds to
     *
     *   32 / 64 == 0.5 pixels ,
     *
     * while for the high accuracy case we have
     *
     *   256/ (1 << 12) = 0.0625 pixels .
     *
     * `precision_jitter' is an epsilon threshold used in
     * `Vertical_Sweep_Span' to deal with small imperfections in the Bezier
     * decomposition (after all, we are working with approximations only);
     * it avoids switching on additional pixels which would cause artifacts
     * otherwise.
     *
     * The value of `precision_jitter' has been determined heuristically.
     *
     */

    if ( High )
    {
      ras.precision_bits   = 12;
      ras.precision_step   = 256;
      ras.precision_jitter = 30;
    }
    else
    {
      ras.precision_bits   = 6;
      ras.precision_step   = 32;
      ras.precision_jitter = 2;
    }

    FT_TRACE6(( "Set_High_Precision(%s)\n", High ? "true" : "false" ));

    ras.precision       = 1 << ras.precision_bits;
    ras.precision_half  = ras.precision / 2;
    ras.precision_shift = ras.precision_bits - Pixel_Bits;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    New_Profile                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Create a new profile in the render pool.                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    aState    :: The state/orientation of the new profile.             */
  /*                                                                       */
  /*    overshoot :: Whether the profile's unrounded start position        */
  /*                 differs by at least a half pixel.                     */
  /*                                                                       */
  /* <Return>                                                              */
  /*   SUCCESS on success.  FAILURE in case of overflow or of incoherent   */
  /*   profile.                                                            */
  /*                                                                       */
  static Bool
  New_Profile( RAS_ARGS TStates  aState,
                        Bool     overshoot )
  {
    if ( !ras.fProfile )
    {
      ras.cProfile  = (PProfile)ras.top;
      ras.fProfile  = ras.cProfile;
      ras.top      += AlignProfileSize;
    }

    if ( ras.top >= ras.maxBuff )
    {
      ras.error = Raster_Err_Overflow;
      return FAILURE;
    }

    ras.cProfile->flags  = 0;
    ras.cProfile->start  = 0;
    ras.cProfile->height = 0;
    ras.cProfile->offset = ras.top;
    ras.cProfile->link   = (PProfile)0;
    ras.cProfile->next   = (PProfile)0;
    ras.cProfile->flags  = ras.dropOutControl;

    switch ( aState )
    {
    case Ascending_State:
      ras.cProfile->flags |= Flow_Up;
      if ( overshoot )
        ras.cProfile->flags |= Overshoot_Bottom;

      FT_TRACE6(( "New ascending profile = %p\n", ras.cProfile ));
      break;

    case Descending_State:
      if ( overshoot )
        ras.cProfile->flags |= Overshoot_Top;
      FT_TRACE6(( "New descending profile = %p\n", ras.cProfile ));
      break;

    default:
      FT_ERROR(( "New_Profile: invalid profile direction\n" ));
      ras.error = Raster_Err_Invalid;
      return FAILURE;
    }

    if ( !ras.gProfile )
      ras.gProfile = ras.cProfile;

    ras.state = aState;
    ras.fresh = TRUE;
    ras.joint = FALSE;

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    End_Profile                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Finalize the current profile.                                      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    overshoot :: Whether the profile's unrounded end position differs  */
  /*                 by at least a half pixel.                             */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success.  FAILURE in case of overflow or incoherency.   */
  /*                                                                       */
  static Bool
  End_Profile( RAS_ARGS Bool  overshoot )
  {
    Long      h;
    PProfile  oldProfile;


    h = (Long)( ras.top - ras.cProfile->offset );

    if ( h < 0 )
    {
      FT_ERROR(( "End_Profile: negative height encountered\n" ));
      ras.error = Raster_Err_Neg_Height;
      return FAILURE;
    }

    if ( h > 0 )
    {
      FT_TRACE6(( "Ending profile %p, start = %ld, height = %ld\n",
                  ras.cProfile, ras.cProfile->start, h ));

      ras.cProfile->height = h;
      if ( overshoot )
      {
        if ( ras.cProfile->flags & Flow_Up )
          ras.cProfile->flags |= Overshoot_Top;
        else
          ras.cProfile->flags |= Overshoot_Bottom;
      }

      oldProfile   = ras.cProfile;
      ras.cProfile = (PProfile)ras.top;

      ras.top += AlignProfileSize;

      ras.cProfile->height = 0;
      ras.cProfile->offset = ras.top;

      oldProfile->next = ras.cProfile;
      ras.num_Profs++;
    }

    if ( ras.top >= ras.maxBuff )
    {
      FT_TRACE1(( "overflow in End_Profile\n" ));
      ras.error = Raster_Err_Overflow;
      return FAILURE;
    }

    ras.joint = FALSE;

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Insert_Y_Turn                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Insert a salient into the sorted list placed on top of the render  */
  /*    pool.                                                              */
  /*                                                                       */
  /* <Input>                                                               */
  /*    New y scanline position.                                           */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success.  FAILURE in case of overflow.                  */
  /*                                                                       */
  static Bool
  Insert_Y_Turn( RAS_ARGS Int  y )
  {
    PLong  y_turns;
    Int    y2, n;


    n       = ras.numTurns - 1;
    y_turns = ras.sizeBuff - ras.numTurns;

    /* look for first y value that is <= */
    while ( n >= 0 && y < y_turns[n] )
      n--;

    /* if it is <, simply insert it, ignore if == */
    if ( n >= 0 && y > y_turns[n] )
      while ( n >= 0 )
      {
        y2 = (Int)y_turns[n];
        y_turns[n] = y;
        y = y2;
        n--;
      }

    if ( n < 0 )
    {
      ras.maxBuff--;
      if ( ras.maxBuff <= ras.top )
      {
        ras.error = Raster_Err_Overflow;
        return FAILURE;
      }
      ras.numTurns++;
      ras.sizeBuff[-ras.numTurns] = y;
    }

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Finalize_Profile_Table                                             */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Adjust all links in the profiles list.                             */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success.  FAILURE in case of overflow.                  */
  /*                                                                       */
  static Bool
  Finalize_Profile_Table( RAS_ARG )
  {
    Int       bottom, top;
    UShort    n;
    PProfile  p;


    n = ras.num_Profs;
    p = ras.fProfile;

    if ( n > 1 && p )
    {
      while ( n > 0 )
      {
        if ( n > 1 )
          p->link = (PProfile)( p->offset + p->height );
        else
          p->link = NULL;

        if ( p->flags & Flow_Up )
        {
          bottom = (Int)p->start;
          top    = (Int)( p->start + p->height - 1 );
        }
        else
        {
          bottom     = (Int)( p->start - p->height + 1 );
          top        = (Int)p->start;
          p->start   = bottom;
          p->offset += p->height - 1;
        }

        if ( Insert_Y_Turn( RAS_VARS bottom )  ||
             Insert_Y_Turn( RAS_VARS top + 1 ) )
          return FAILURE;

        p = p->link;
        n--;
      }
    }
    else
      ras.fProfile = NULL;

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Split_Conic                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Subdivide one conic Bezier into two joint sub-arcs in the Bezier   */
  /*    stack.                                                             */
  /*                                                                       */
  /* <Input>                                                               */
  /*    None (subdivided Bezier is taken from the top of the stack).       */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This routine is the `beef' of this component.  It is  _the_ inner  */
  /*    loop that should be optimized to hell to get the best performance. */
  /*                                                                       */
  static void
  Split_Conic( TPoint*  base )
  {
    Long  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;

    /* hand optimized.  gcc doesn't seem to be too good at common      */
    /* expression substitution and instruction scheduling ;-)          */
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Split_Cubic                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Subdivide a third-order Bezier arc into two joint sub-arcs in the  */
  /*    Bezier stack.                                                      */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This routine is the `beef' of the component.  It is one of _the_   */
  /*    inner loops that should be optimized like hell to get the best     */
  /*    performance.                                                       */
  /*                                                                       */
  static void
  Split_Cubic( TPoint*  base )
  {
    Long  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 + 1 ) >> 1;
    base[5].x = b = ( base[3].x + d + 1 ) >> 1;
    c = ( c + d + 1 ) >> 1;
    base[2].x = a = ( a + c + 1 ) >> 1;
    base[4].x = b = ( b + c + 1 ) >> 1;
    base[3].x = ( a + b + 1 ) >> 1;

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


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Line_Up                                                            */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Compute the x-coordinates of an ascending line segment and store   */
  /*    them in the render pool.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    x1   :: The x-coordinate of the segment's start point.             */
  /*                                                                       */
  /*    y1   :: The y-coordinate of the segment's start point.             */
  /*                                                                       */
  /*    x2   :: The x-coordinate of the segment's end point.               */
  /*                                                                       */
  /*    y2   :: The y-coordinate of the segment's end point.               */
  /*                                                                       */
  /*    miny :: A lower vertical clipping bound value.                     */
  /*                                                                       */
  /*    maxy :: An upper vertical clipping bound value.                    */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success, FAILURE on render pool overflow.               */
  /*                                                                       */
  static Bool
  Line_Up( RAS_ARGS Long  x1,
                    Long  y1,
                    Long  x2,
                    Long  y2,
                    Long  miny,
                    Long  maxy )
  {
    Long   Dx, Dy;
    Int    e1, e2, f1, f2, size;     /* XXX: is `Short' sufficient? */
    Long   Ix, Rx, Ax;

    PLong  top;


    Dx = x2 - x1;
    Dy = y2 - y1;

    if ( Dy <= 0 || y2 < miny || y1 > maxy )
      return SUCCESS;

    if ( y1 < miny )
    {
      /* Take care: miny-y1 can be a very large value; we use     */
      /*            a slow MulDiv function to avoid clipping bugs */
      x1 += SMulDiv( Dx, miny - y1, Dy );
      e1  = (Int)TRUNC( miny );
      f1  = 0;
    }
    else
    {
      e1 = (Int)TRUNC( y1 );
      f1 = (Int)FRAC( y1 );
    }

    if ( y2 > maxy )
    {
      /* x2 += FMulDiv( Dx, maxy - y2, Dy );  UNNECESSARY */
      e2  = (Int)TRUNC( maxy );
      f2  = 0;
    }
    else
    {
      e2 = (Int)TRUNC( y2 );
      f2 = (Int)FRAC( y2 );
    }

    if ( f1 > 0 )
    {
      if ( e1 == e2 )
        return SUCCESS;
      else
      {
        x1 += SMulDiv( Dx, ras.precision - f1, Dy );
        e1 += 1;
      }
    }
    else
      if ( ras.joint )
      {
        ras.top--;
        ras.joint = FALSE;
      }

    ras.joint = (char)( f2 == 0 );

    if ( ras.fresh )
    {
      ras.cProfile->start = e1;
      ras.fresh           = FALSE;
    }

    size = e2 - e1 + 1;
    if ( ras.top + size >= ras.maxBuff )
    {
      ras.error = Raster_Err_Overflow;
      return FAILURE;
    }

    if ( Dx > 0 )
    {
      Ix = SMulDiv( ras.precision, Dx, Dy);
      Rx = ( ras.precision * Dx ) % Dy;
      Dx = 1;
    }
    else
    {
      Ix = SMulDiv( ras.precision, -Dx, Dy) * -1;
      Rx =    ( ras.precision * -Dx ) % Dy;
      Dx = -1;
    }

    Ax  = -Dy;
    top = ras.top;

    while ( size > 0 )
    {
      *top++ = x1;

      x1 += Ix;
      Ax += Rx;
      if ( Ax >= 0 )
      {
        Ax -= Dy;
        x1 += Dx;
      }
      size--;
    }

    ras.top = top;
    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Line_Down                                                          */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Compute the x-coordinates of an descending line segment and store  */
  /*    them in the render pool.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    x1   :: The x-coordinate of the segment's start point.             */
  /*                                                                       */
  /*    y1   :: The y-coordinate of the segment's start point.             */
  /*                                                                       */
  /*    x2   :: The x-coordinate of the segment's end point.               */
  /*                                                                       */
  /*    y2   :: The y-coordinate of the segment's end point.               */
  /*                                                                       */
  /*    miny :: A lower vertical clipping bound value.                     */
  /*                                                                       */
  /*    maxy :: An upper vertical clipping bound value.                    */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success, FAILURE on render pool overflow.               */
  /*                                                                       */
  static Bool
  Line_Down( RAS_ARGS Long  x1,
                      Long  y1,
                      Long  x2,
                      Long  y2,
                      Long  miny,
                      Long  maxy )
  {
    Bool  result, fresh;


    fresh  = ras.fresh;

    result = Line_Up( RAS_VARS x1, -y1, x2, -y2, -maxy, -miny…