ftraster.c

Qt/Embedded是一个多平台的C++图形用户界面应用程序框架

/***************************************************************************/
/*                                                                         */
/*  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.                                        */
/*                                                                         */
/***************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* The `raster' component implements FreeType's scan-line converter, the */
  /* one used to generate bitmaps and pixmaps from vectorial outline       */
  /* descriptions.                                                         */
  /*                                                                       */
  /* It has been rewritten entirely for FreeType 2.0, in order to become   */
  /* completely independent of the rest of the library.  It should now be  */
  /* possible to include it more easily in all kinds of libraries and      */
  /* applications, which do not necessarily need the font engines and API. */
  /*                                                                       */
  /* This version contains the following features:                         */
  /*                                                                       */
  /* - Support for third-order Bezier arcs.                                */
  /*                                                                       */
  /* - Improved performance of the 5-levels anti-aliasing algorithm.       */
  /*                                                                       */
  /* - 17-levels anti-aliasing for smoother curves, though the difference  */
  /*   isn't always noticeable, depending on your palette.                 */
  /*                                                                       */
  /* - An API to decompose a raster outline into a path (i.e., into a      */
  /*   a series of segments and arcs).                                     */
  /*                                                                       */
  /* Planned additions:                                                    */
  /*                                                                       */
  /* - Getting rid of the second pass for horizontal drop-out detection.   */
  /*   I've got a few ideas, but I'll have to experiment in Pascal with    */
  /*   them.  to avoid damaging of the rendering of glyphs at small sizes. */
  /*                                                                       */
  /* - Adding a `composition' callback, which should be invoked during     */
  /*   anti-aliased rendering.  In short, it will allow line-by-line       */
  /*   composition (i.e., transparencies, etc.) of the output in a fairly  */
  /*   portable way.  Of course, a single sweep is required there.         */
  /*                                                                       */
  /*************************************************************************/


#include <ftraster.h>
#ifndef _STANDALONE_
#include <ftconfig.h>
#endif

#ifndef EXPORT_FUNC
#define EXPORT_FUNC  /* nothing */
#endif

#undef  FT_COMPONENT
#define FT_COMPONENT  trace_raster

#ifdef _STANDALONE_

  /*************************************************************************/
  /*                                                                       */
  /* The following defines are used when the raster is compiled as a       */
  /* stand-alone object.  Each of them is commented, and you're free to    */
  /* toggle them to suit your needs.                                       */
  /*                                                                       */
  /*************************************************************************/

  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_INT_IS_32                                                   */
  /*                                                                       */
  /*   Set this configuration macro to the unsigned type which has 32      */
  /*   bits.                                                               */
  /*                                                                       */
#define FT_RASTER_INT_IS_32


  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_OPTION_ANTI_ALIAS                                           */
  /*                                                                       */
  /*   Define this configuration macro if you want to support              */
  /*   anti-aliasing.                                                      */
  /*                                                                       */
#define FT_RASTER_OPTION_ANTI_ALIAS


  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_OPTION_CONIC_BEZIERS                                        */
  /*                                                                       */
  /*   Define this configuration macro if your source outlines contain     */
  /*   second-order Bezier arcs.  Typically, these are TrueType outlines.  */
  /*                                                                       */
#define FT_RASTER_CONIC_BEZIERS


  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_OPTION_CUBIC_BEZIERS                                        */
  /*                                                                       */
  /*   Define this configuration macro if your source outlines contain     */
  /*   third-order Bezier arcs.  Typically, these are Type1 outlines.      */
  /*                                                                       */
#define FT_RASTER_CUBIC_BEZIERS


  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_ANTI_ALIAS_5                                                */
  /*                                                                       */
  /*   Define this configuration macro if you want to enable the 5-grays   */
  /*   anti-aliasing mode.  Ignored if FT_RASTER_OPTION_ANTI_ALIAS isn't   */
  /*   defined.                                                            */
  /*                                                                       */
#define FT_RASTER_ANTI_ALIAS_5


  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_ANTI_ALIAS_17                                               */
  /*                                                                       */
  /*   Define this configuration macro if you want to enable the 17-grays  */
  /*   anti-aliasing mode.  Ignored if FT_RASTER_OPTION_ANTI_ALIAS isn't   */
  /*   defined.                                                            */
  /*                                                                       */
/* #define FT_RASTER_ANTI_ALIAS_17 */


  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_LITTLE_ENDIAN                                               */
  /* FT_RASTER_BIG_ENDIAN                                                  */
  /*                                                                       */
  /*   The default anti-alias routines are processor-independent, but      */
  /*   slow.  Define one of these macros to suit your own system, and      */
  /*   enjoy greatly improved rendering speed.                             */
  /*                                                                       */

/* #define FT_RASTER_LITTLE_ENDIAN */
/* #define FT_RASTER_BIG_ENDIAN    */

  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_CONSTANT_PRECISION                                          */
  /*                                                                       */
  /*   Define this configuration macro if you want to use a constant       */
  /*   precision for the internal sub-pixel coordinates. Otherwise, the    */
  /*   precision is either 64 or 1024 units per pixel, depending on the    */
  /*   outline's "high_precision" flag..                                   */
  /*                                                                       */
  /*   This results in a speed boost, but the macro can be undefined if    */
  /*   it results in rendering errors (mainly changed drop-outs)..         */
  /*                                                                       */
#define FT_RASTER_CONSTANT_PRECISION


  /*************************************************************************/
  /*                                                                       */
  /* FT_PRECISION_BITS                                                     */
  /*                                                                       */
  /*   When the macro FT_RASTER_CONSTANT_PRECISION is defined, this        */
  /*   constant holds the number of bits used for the internal sub-pixels  */
  /*                                                                       */
  /*   This number should be at least 6, but use at least 8 if you         */
  /*   intend to generate small glyph images (use 6 for a printer, for     */
  /*   example..)                                                          */
  /*                                                                       */
#define FT_PRECISION_BITS 8


  /*************************************************************************/
  /*                                                                       */
  /* FT_DYNAMIC_BEZIER_STEPS                                               */
  /*                                                                       */
  /*   Set this macro to enable the bezier decomposition to be             */
  /*   dynamically computed. This is interesting when the precision is     */
  /*   constant, as it speeds things a bit while keeping a very good       */
  /*   accuracy on the bezier intersections..                              */
  /*                                                                       */
#define FT_DYNAMIC_BEZIER_STEPS


#else /* _STANDALONE_ */

#include <freetype.h>
#include <ftconfig.h>

  /*************************************************************************/
  /*                                                                       */
  /* The following defines are used when the raster is compiled within the */
  /* FreeType base layer.  Don't change these unless you really know what  */
  /* you're doing.                                                         */
  /*                                                                       */
  /*************************************************************************/


#ifdef FT_CONFIG_OPTION_ANTI_ALIAS
#define FT_RASTER_OPTION_ANTI_ALIAS
#endif

#define FT_RASTER_CONIC_BEZIERS
#define FT_RASTER_CUBIC_BEZIERS

#define FT_RASTER_ANTI_ALIAS_5
/* #define  FT_RASTER_ANTI_ALIAS_17 */

#ifdef FT_CONFIG_OPTION_LITTLE_ENDIAN
#define FT_RASTER_LITTLE_ENDIAN
#endif

#ifdef FT_CONFIG_OPTION_BIG_ENDIAN
#define FT_RASTER_BIG_ENDIAN
#endif

#define FT_RASTER_CONSTANT_PRECISION
#define FT_DYNAMIC_BEZIER_STEPS
#define FT_PRECISION_BITS    8

#endif /* _STANDALONE_ */


/* to keep the compiler happy */
#ifndef PTRACE2
#define PTRACE2(x)  /*void*/
#endif

  /*************************************************************************/
  /*                                                                       */
  /* FT_RASTER_ANY_ENDIAN indicates that no endianess was defined by one   */
  /* of the configuration macros.                                          */
  /*                                                                       */
#if !defined( FT_RASTER_LITTLE_ENDIAN ) && !defined( FT_RASTER_BIG_ENDIAN )
#define FT_RASTER_ANY_ENDIAN
#endif


  /*************************************************************************/
  /*                                                                       */
  /* The rasterizer is a very general purpose component.  Please leave the */
  /* following redefinitions here (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 UNUSED
#define UNUSED( arg )  ( (void)(arg) )
#endif


#undef  FAILURE
#define FAILURE  TRUE

#undef  SUCCESS
#define SUCCESS  FALSE

#ifndef ABS
#define ABS(x)  ( (x) < 0 ? -(x) : (x) )
#endif

  /*************************************************************************/
  /*                                                                       */
  /* Please don't touch the following macros. Their importance is          */
  /* historical to FreeType, but they have some nice effects, like getting */
  /* rid of all `->' symbols when accessing the raster object (replacing   */
  /* them with a simple `.').                                              */
  /*                                                                       */
  /*************************************************************************/

  /* used in function signatures to define the _first_ argument */
#define RAS_ARG_  FT_Raster  raster,
#define RAS_ARG   FT_Raster  raster

  /* used to call a function within this component, first parameter */
#define RAS_VAR_  raster,
#define RAS_VAR   raster

  /* used to access the current raster object, with a `.' instead of a */
  /* `->'                                                              */
#define ras       (*raster)


  /*************************************************************************/
  /*                                                                       */
  /* Error codes returned by the scan-line converter/raster.               */
  /*                                                                       */
#define ErrRaster_Ok                     0
#define ErrRaster_Uninitialized_Object   1
#define ErrRaster_Overflow               2
#define ErrRaster_Negative_Height        3
#define ErrRaster_Invalid_Outline        4
#define ErrRaster_Invalid_Map            5
#define ErrRaster_AntiAlias_Unsupported  6
#define ErrRaster_Invalid_Pool           7
#define ErrRaster_Unimplemented          8