ftraster.c

qt-embedded-2.3.8.tar.gz源码

/***************************************************************************/
/*                                                                         */
/*  ftraster.c                                                             */
/*                                                                         */
/*    The FreeType glyph rasterizer (body).                                */
/*                                                                         */
/*  Copyright 1996-2000 by                                                 */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/

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


#ifdef FT_FLAT_COMPILE
#  include "ftraster.h"
#else
#  include <raster/ftraster.h>
#endif
#include <freetype/internal/ftcalc.h>      /* for FT_MulDiv() only */


  /*************************************************************************/
  /*                                                                       */
  /* 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.          */
  /*                                                                       */
  /*   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 propertly.                                    */
  /*                                                                       */
  /*************************************************************************/


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

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

  /* The default render pool size in bytes */
#define RASTER_RENDER_POOL  8192

  /* undefine FT_RASTER_OPTION_ANTI_ALIASING if you do not want to support */
  /* 5-levels anti-aliasing                                                */
#ifdef FT_CONFIG_OPTION_5_GRAY_LEVELS
#define FT_RASTER_OPTION_ANTI_ALIASING
#endif

  /* 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 */
#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


#else /* _STANDALONE_ */


#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftdebug.h> /* for FT_TRACE() and FT_ERROR() */

#define Raster_Err_None         FT_Err_Ok
#define Raster_Err_Not_Ini      FT_Err_Raster_Uninitialized
#define Raster_Err_Overflow     FT_Err_Raster_Overflow
#define Raster_Err_Neg_Height   FT_Err_Raster_Negative_Height
#define Raster_Err_Invalid      FT_Err_Invalid_Outline
#define Raster_Err_Unsupported  FT_Err_Cannot_Render_Glyph


#endif /* _STANDALONE_ */


  /* 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 long   ULong;

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

  typedef struct  TPoint_
  {
    Long  x;
    Long  y;

  } TPoint;


  typedef enum  TFlow_
  {
    Flow_None = 0,
    Flow_Up   = 1,
    Flow_Down = -1

  } TFlow;


  /* States of each line, arc, and profile */
  typedef enum  TStates_
  {
    Unknown,
    Ascending,
    Descending,
    Flat

  } TStates;


  typedef struct TProfile_  TProfile;
  typedef TProfile*         PProfile;

  struct  TProfile_
  {
    FT_F26Dot6  X;           /* current coordinate during sweep        */
    PProfile    link;        /* link to next profile - various purpose */
    PLong       offset;      /* start of profile's data in render pool */
    Int         flow;        /* Profile orientation: Asc/Descending    */
    Long        height;      /* profile's height in scanlines          */
    Long        start;       /* profile's starting scanline            */

    UShort      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  TBand_
  {
    Short  y_min;   /* band's minimum */
    Short  y_max;   /* band's maximum */

  } TBand;


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


#ifdef TT_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 /* TT_STATIC_RASTER */


#define RAS_ARGS       TRaster_Instance*  raster,
#define RAS_ARG        TRaster_Instance*  raster

#define RAS_VARS       raster,
#define RAS_VAR        raster

#define FT_UNUSED_RASTER  FT_UNUSED( raster )


#endif /* TT_STATIC_RASTER */


  typedef struct TRaster_Instance_  TRaster_Instance;


  /* 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 */

#define FLOOR( x )    ( (x) & -ras.precision )
#define CEILING( x )  ( ( (x) + ras.precision - 1 ) & -ras.precision )