ftcalc.h revision a38fc482eeeb2c1929803c233835369dcf1b8781 
1/***************************************************************************/
2/*                                                                         */
3/*  ftcalc.h                                                               */
4/*                                                                         */
5/*    Arithmetic computations (specification).                             */
6/*                                                                         */
7/*  Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006, 2008 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
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#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
169#define ROUND_F26DOT6( x )     ( x >= 0 ? (    ( (x) + 32 ) & -64 )     \
170                                        : ( -( ( 32 - (x) ) & -64 ) ) )
171
172
173FT_END_HEADER
174
175#endif /* __FTCALC_H__ */
176
177
178/* END */
179