include/freetype/internal/ftcalc.h

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftcalc.h                                                               */
   4 /*                                                                         */
   5 /*    Arithmetic computations (specification).                             */
   6 /*                                                                         */
   7 /*  Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009 by       */
   8 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
   9 /*                                                                         */
  10 /*  This file is part of the FreeType project, and may only be used,       */
  11 /*  modified, and distributed under the terms of the FreeType project      */
  12 /*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
  13 /*  this file you indicate that you have read the license and              */
  14 /*  understand and accept it fully.                                        */
  15 /*                                                                         */
  16 /***************************************************************************/
  17
  18
  19 #ifndef __FTCALC_H__
  20 #define __FTCALC_H__
  21
  22
  23 #include <ft2build.h>
  24 #include FT_FREETYPE_H
  25
  26
  27 FT_BEGIN_HEADER
  28
  29
  30   /*************************************************************************/
  31   /*                                                                       */
  32   /* <Function>                                                            */
  33   /*    FT_FixedSqrt                                                       */
  34   /*                                                                       */
  35   /* <Description>                                                         */
  36   /*    Computes the square root of a 16.16 fixed point value.             */
  37   /*                                                                       */
  38   /* <Input>                                                               */
  39   /*    x :: The value to compute the root for.                            */
  40   /*                                                                       */
  41   /* <Return>                                                              */
  42   /*    The result of `sqrt(x)'.                                           */
  43   /*                                                                       */
  44   /* <Note>                                                                */
  45   /*    This function is not very fast.                                    */
  46   /*                                                                       */
  47   FT_BASE( FT_Int32 )
  48   FT_SqrtFixed( FT_Int32  x );
  49
  50
  51 #ifdef FT_CONFIG_OPTION_OLD_INTERNALS
  52
  53   /*************************************************************************/
  54   /*                                                                       */
  55   /* <Function>                                                            */
  56   /*    FT_Sqrt32                                                          */
  57   /*                                                                       */
  58   /* <Description>                                                         */
  59   /*    Computes the square root of an Int32 integer (which will be        */
  60   /*    handled as an unsigned long value).                                */
  61   /*                                                                       */
  62   /* <Input>                                                               */
  63   /*    x :: The value to compute the root for.                            */
  64   /*                                                                       */
  65   /* <Return>                                                              */
  66   /*    The result of `sqrt(x)'.                                           */
  67   /*                                                                       */
  68   FT_EXPORT( FT_Int32 )
  69   FT_Sqrt32( FT_Int32  x );
  70
  71 #endif /* FT_CONFIG_OPTION_OLD_INTERNALS */
  72
  73
  74   /*************************************************************************/
  75   /*                                                                       */
  76   /* FT_MulDiv() and FT_MulFix() are declared in freetype.h.               */
  77   /*                                                                       */
  78   /*************************************************************************/
  79
  80
  81 #ifdef TT_USE_BYTECODE_INTERPRETER
  82
  83   /*************************************************************************/
  84   /*                                                                       */
  85   /* <Function>                                                            */
  86   /*    FT_MulDiv_No_Round                                                 */
  87   /*                                                                       */
  88   /* <Description>                                                         */
  89   /*    A very simple function used to perform the computation `(a*b)/c'   */
  90   /*    (without rounding) with maximal accuracy (it uses a 64-bit         */
  91   /*    intermediate integer whenever necessary).                          */
  92   /*                                                                       */
  93   /*    This function isn't necessarily as fast as some processor specific */
  94   /*    operations, but is at least completely portable.                   */
  95   /*                                                                       */
  96   /* <Input>                                                               */
  97   /*    a :: The first multiplier.                                         */
  98   /*    b :: The second multiplier.                                        */
  99   /*    c :: The divisor.                                                  */
 100   /*                                                                       */
 101   /* <Return>                                                              */
 102   /*    The result of `(a*b)/c'.  This function never traps when trying to */
 103   /*    divide by zero; it simply returns `MaxInt' or `MinInt' depending   */
 104   /*    on the signs of `a' and `b'.                                       */
 105   /*                                                                       */
 106   FT_BASE( FT_Long )
 107   FT_MulDiv_No_Round( FT_Long  a,
 108                       FT_Long  b,
 109                       FT_Long  c );
 110
 111 #endif /* TT_USE_BYTECODE_INTERPRETER */
 112
 113
 114   /*
 115    *  A variant of FT_Matrix_Multiply which scales its result afterwards.
 116    *  The idea is that both `a' and `b' are scaled by factors of 10 so that
 117    *  the values are as precise as possible to get a correct result during
 118    *  the 64bit multiplication.  Let `sa' and `sb' be the scaling factors of
 119    *  `a' and `b', respectively, then the scaling factor of the result is
 120    *  `sa*sb'.
 121    */
 122   FT_BASE( void )
 123   FT_Matrix_Multiply_Scaled( const FT_Matrix*  a,
 124                              FT_Matrix        *b,
 125                              FT_Long           scaling );
 126
 127
 128   /*
 129    *  A variant of FT_Vector_Transform.  See comments for
 130    *  FT_Matrix_Multiply_Scaled.
 131    */
 132
 133   FT_BASE( void )
 134   FT_Vector_Transform_Scaled( FT_Vector*        vector,
 135                               const FT_Matrix*  matrix,
 136                               FT_Long           scaling );
 137
 138
 139   /*
 140    *  Return -1, 0, or +1, depending on the orientation of a given corner.
 141    *  We use the Cartesian coordinate system, with positive vertical values
 142    *  going upwards.  The function returns +1 if the corner turns to the
 143    *  left, -1 to the right, and 0 for undecidable cases.
 144    */
 145   FT_BASE( FT_Int )
 146   ft_corner_orientation( FT_Pos  in_x,
 147                          FT_Pos  in_y,
 148                          FT_Pos  out_x,
 149                          FT_Pos  out_y );
 150
 151   /*
 152    *  Return TRUE if a corner is flat or nearly flat.  This is equivalent to
 153    *  saying that the angle difference between the `in' and `out' vectors is
 154    *  very small.
 155    */
 156   FT_BASE( FT_Int )
 157   ft_corner_is_flat( FT_Pos  in_x,
 158                      FT_Pos  in_y,
 159                      FT_Pos  out_x,
 160                      FT_Pos  out_y );
 161
 162
 163 #define INT_TO_F26DOT6( x )    ( (FT_Long)(x) << 6  )
 164 #define INT_TO_F2DOT14( x )    ( (FT_Long)(x) << 14 )
 165 #define INT_TO_FIXED( x )      ( (FT_Long)(x) << 16 )
 166 #define F2DOT14_TO_FIXED( x )  ( (FT_Long)(x) << 2  )
 167 #define FLOAT_TO_FIXED( x )    ( (FT_Long)( x * 65536.0 ) )
 168 #define FIXED_TO_INT( x )      ( FT_RoundFix( x ) >> 16 )
 169
 170 #define ROUND_F26DOT6( x )     ( x >= 0 ? (    ( (x) + 32 ) & -64 )     \
 171                                         : ( -( ( 32 - (x) ) & -64 ) ) )
 172
 173
 174 FT_END_HEADER
 175
 176 #endif /* __FTCALC_H__ */
 177
 178
 179 /* END */