ftcalc.h revision ee451cb395940862dad63c85adfe8f2fd55e864c 
1/***************************************************************************/
2/*                                                                         */
3/*  ftcalc.h                                                               */
4/*                                                                         */
5/*    Arithmetic computations (specification).                             */
6/*                                                                         */
7/*  Copyright 1996-2006, 2008, 2009, 2012-2013 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 "../freetype.h"
25
26
27FT_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  /*************************************************************************/
52  /*                                                                       */
53  /* FT_MulDiv() and FT_MulFix() are declared in freetype.h.               */
54  /*                                                                       */
55  /*************************************************************************/
56
57
58  /*************************************************************************/
59  /*                                                                       */
60  /* <Function>                                                            */
61  /*    FT_MulDiv_No_Round                                                 */
62  /*                                                                       */
63  /* <Description>                                                         */
64  /*    A very simple function used to perform the computation `(a*b)/c'   */
65  /*    (without rounding) with maximum accuracy (it uses a 64-bit         */
66  /*    intermediate integer whenever necessary).                          */
67  /*                                                                       */
68  /*    This function isn't necessarily as fast as some processor specific */
69  /*    operations, but is at least completely portable.                   */
70  /*                                                                       */
71  /* <Input>                                                               */
72  /*    a :: The first multiplier.                                         */
73  /*    b :: The second multiplier.                                        */
74  /*    c :: The divisor.                                                  */
75  /*                                                                       */
76  /* <Return>                                                              */
77  /*    The result of `(a*b)/c'.  This function never traps when trying to */
78  /*    divide by zero; it simply returns `MaxInt' or `MinInt' depending   */
79  /*    on the signs of `a' and `b'.                                       */
80  /*                                                                       */
81  FT_BASE( FT_Long )
82  FT_MulDiv_No_Round( FT_Long  a,
83                      FT_Long  b,
84                      FT_Long  c );
85
86
87  /*
88   *  A variant of FT_Matrix_Multiply which scales its result afterwards.
89   *  The idea is that both `a' and `b' are scaled by factors of 10 so that
90   *  the values are as precise as possible to get a correct result during
91   *  the 64bit multiplication.  Let `sa' and `sb' be the scaling factors of
92   *  `a' and `b', respectively, then the scaling factor of the result is
93   *  `sa*sb'.
94   */
95  FT_BASE( void )
96  FT_Matrix_Multiply_Scaled( const FT_Matrix*  a,
97                             FT_Matrix        *b,
98                             FT_Long           scaling );
99
100
101  /*
102   *  A variant of FT_Vector_Transform.  See comments for
103   *  FT_Matrix_Multiply_Scaled.
104   */
105  FT_BASE( void )
106  FT_Vector_Transform_Scaled( FT_Vector*        vector,
107                              const FT_Matrix*  matrix,
108                              FT_Long           scaling );
109
110
111  /*
112   *  Return -1, 0, or +1, depending on the orientation of a given corner.
113   *  We use the Cartesian coordinate system, with positive vertical values
114   *  going upwards.  The function returns +1 if the corner turns to the
115   *  left, -1 to the right, and 0 for undecidable cases.
116   */
117  FT_BASE( FT_Int )
118  ft_corner_orientation( FT_Pos  in_x,
119                         FT_Pos  in_y,
120                         FT_Pos  out_x,
121                         FT_Pos  out_y );
122
123  /*
124   *  Return TRUE if a corner is flat or nearly flat.  This is equivalent to
125   *  saying that the angle difference between the `in' and `out' vectors is
126   *  very small.
127   */
128  FT_BASE( FT_Int )
129  ft_corner_is_flat( FT_Pos  in_x,
130                     FT_Pos  in_y,
131                     FT_Pos  out_x,
132                     FT_Pos  out_y );
133
134
135  /*
136   *  Return the most significant bit index.
137   */
138  FT_BASE( FT_Int )
139  FT_MSB( FT_UInt32  z );
140
141
142  /*
143   *  Return sqrt(x*x+y*y), which is the same as `FT_Vector_Length' but uses
144   *  two fixed-point arguments instead.
145   */
146  FT_BASE( FT_Fixed )
147  FT_Hypot( FT_Fixed  x,
148            FT_Fixed  y );
149
150
151#define INT_TO_F26DOT6( x )    ( (FT_Long)(x) << 6  )
152#define INT_TO_F2DOT14( x )    ( (FT_Long)(x) << 14 )
153#define INT_TO_FIXED( x )      ( (FT_Long)(x) << 16 )
154#define F2DOT14_TO_FIXED( x )  ( (FT_Long)(x) << 2  )
155#define FLOAT_TO_FIXED( x )    ( (FT_Long)( x * 65536.0 ) )
156#define FIXED_TO_INT( x )      ( FT_RoundFix( x ) >> 16 )
157
158#define ROUND_F26DOT6( x )     ( x >= 0 ? (    ( (x) + 32 ) & -64 )     \
159                                        : ( -( ( 32 - (x) ) & -64 ) ) )
160
161
162FT_END_HEADER
163
164#endif /* __FTCALC_H__ */
165
166
167/* END */
168