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 FT_FREETYPE_H 25 26 27 FT_BEGIN_HEADER 28 29 30 #if 0 31 32 /*************************************************************************/ 33 /* */ 34 /* <Function> */ 35 /* FT_SqrtFixed */ 36 /* */ 37 /* <Description> */ 38 /* Computes the square root of a 16.16 fixed-point value. */ 39 /* */ 40 /* <Input> */ 41 /* x :: The value to compute the root for. */ 42 /* */ 43 /* <Return> */ 44 /* The result of `sqrt(x)'. */ 45 /* */ 46 /* <Note> */ 47 /* This function is not very fast. */ 48 /* */ 49 FT_BASE( FT_Int32 ) 50 FT_SqrtFixed( FT_Int32 x ); 51 52 #endif /* 0 */ 53 54 55 /*************************************************************************/ 56 /* */ 57 /* FT_MulDiv() and FT_MulFix() are declared in freetype.h. */ 58 /* */ 59 /*************************************************************************/ 60 61 62 /*************************************************************************/ 63 /* */ 64 /* <Function> */ 65 /* FT_MulDiv_No_Round */ 66 /* */ 67 /* <Description> */ 68 /* A very simple function used to perform the computation `(a*b)/c' */ 69 /* (without rounding) with maximum accuracy (it uses a 64-bit */ 70 /* intermediate integer whenever necessary). */ 71 /* */ 72 /* This function isn't necessarily as fast as some processor specific */ 73 /* operations, but is at least completely portable. */ 74 /* */ 75 /* <Input> */ 76 /* a :: The first multiplier. */ 77 /* b :: The second multiplier. */ 78 /* c :: The divisor. */ 79 /* */ 80 /* <Return> */ 81 /* The result of `(a*b)/c'. This function never traps when trying to */ 82 /* divide by zero; it simply returns `MaxInt' or `MinInt' depending */ 83 /* on the signs of `a' and `b'. */ 84 /* */ 85 FT_BASE( FT_Long ) 86 FT_MulDiv_No_Round( FT_Long a, 87 FT_Long b, 88 FT_Long c ); 89 90 91 /* 92 * A variant of FT_Matrix_Multiply which scales its result afterwards. 93 * The idea is that both `a' and `b' are scaled by factors of 10 so that 94 * the values are as precise as possible to get a correct result during 95 * the 64bit multiplication. Let `sa' and `sb' be the scaling factors of 96 * `a' and `b', respectively, then the scaling factor of the result is 97 * `sa*sb'. 98 */ 99 FT_BASE( void ) 100 FT_Matrix_Multiply_Scaled( const FT_Matrix* a, 101 FT_Matrix *b, 102 FT_Long scaling ); 103 104 105 /* 106 * A variant of FT_Vector_Transform. See comments for 107 * FT_Matrix_Multiply_Scaled. 108 */ 109 FT_BASE( void ) 110 FT_Vector_Transform_Scaled( FT_Vector* vector, 111 const FT_Matrix* matrix, 112 FT_Long scaling ); 113 114 115 /* 116 * Return -1, 0, or +1, depending on the orientation of a given corner. 117 * We use the Cartesian coordinate system, with positive vertical values 118 * going upwards. The function returns +1 if the corner turns to the 119 * left, -1 to the right, and 0 for undecidable cases. 120 */ 121 FT_BASE( FT_Int ) 122 ft_corner_orientation( FT_Pos in_x, 123 FT_Pos in_y, 124 FT_Pos out_x, 125 FT_Pos out_y ); 126 127 /* 128 * Return TRUE if a corner is flat or nearly flat. This is equivalent to 129 * saying that the angle difference between the `in' and `out' vectors is 130 * very small. 131 */ 132 FT_BASE( FT_Int ) 133 ft_corner_is_flat( FT_Pos in_x, 134 FT_Pos in_y, 135 FT_Pos out_x, 136 FT_Pos out_y ); 137 138 139 /* 140 * Return the most significant bit index. 141 */ 142 FT_BASE( FT_Int ) 143 FT_MSB( FT_UInt32 z ); 144 145 146 /* 147 * Return sqrt(x*x+y*y), which is the same as `FT_Vector_Length' but uses 148 * two fixed-point arguments instead. 149 */ 150 FT_BASE( FT_Fixed ) 151 FT_Hypot( FT_Fixed x, 152 FT_Fixed y ); 153 154 155 #define INT_TO_F26DOT6( x ) ( (FT_Long)(x) << 6 ) 156 #define INT_TO_F2DOT14( x ) ( (FT_Long)(x) << 14 ) 157 #define INT_TO_FIXED( x ) ( (FT_Long)(x) << 16 ) 158 #define F2DOT14_TO_FIXED( x ) ( (FT_Long)(x) << 2 ) 159 #define FLOAT_TO_FIXED( x ) ( (FT_Long)( x * 65536.0 ) ) 160 #define FIXED_TO_INT( x ) ( FT_RoundFix( x ) >> 16 ) 161 162 #define ROUND_F26DOT6( x ) ( x >= 0 ? ( ( (x) + 32 ) & -64 ) \ 163 : ( -( ( 32 - (x) ) & -64 ) ) ) 164 165 166 FT_END_HEADER 167 168 #endif /* __FTCALC_H__ */ 169 170 171 /* END */ 172
