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SkScalar.h
1 /*
2  * Copyright 2006 The Android Open Source Project
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef SkScalar_DEFINED
9 #define SkScalar_DEFINED
10 
11 #include "../private/SkFloatingPoint.h"
12 
13 #undef SK_SCALAR_IS_FLOAT
14 #define SK_SCALAR_IS_FLOAT 1
15 
16 typedef float SkScalar;
17 
18 #define SK_Scalar1 1.0f
19 #define SK_ScalarHalf 0.5f
20 #define SK_ScalarSqrt2 1.41421356f
21 #define SK_ScalarPI 3.14159265f
22 #define SK_ScalarTanPIOver8 0.414213562f
23 #define SK_ScalarRoot2Over2 0.707106781f
24 #define SK_ScalarMax 3.402823466e+38f
25 #define SK_ScalarInfinity SK_FloatInfinity
26 #define SK_ScalarNegativeInfinity SK_FloatNegativeInfinity
27 #define SK_ScalarNaN SK_FloatNaN
28 
29 #define SkScalarFloorToScalar(x) sk_float_floor(x)
30 #define SkScalarCeilToScalar(x) sk_float_ceil(x)
31 #define SkScalarRoundToScalar(x) sk_float_floor((x) + 0.5f)
32 #define SkScalarTruncToScalar(x) sk_float_trunc(x)
33 
34 #define SkScalarFloorToInt(x) sk_float_floor2int(x)
35 #define SkScalarCeilToInt(x) sk_float_ceil2int(x)
36 #define SkScalarRoundToInt(x) sk_float_round2int(x)
37 
38 #define SkScalarAbs(x) sk_float_abs(x)
39 #define SkScalarCopySign(x, y) sk_float_copysign(x, y)
40 #define SkScalarMod(x, y) sk_float_mod(x,y)
41 #define SkScalarSqrt(x) sk_float_sqrt(x)
42 #define SkScalarPow(b, e) sk_float_pow(b, e)
43 
44 #define SkScalarSin(radians) (float)sk_float_sin(radians)
45 #define SkScalarCos(radians) (float)sk_float_cos(radians)
46 #define SkScalarTan(radians) (float)sk_float_tan(radians)
47 #define SkScalarASin(val) (float)sk_float_asin(val)
48 #define SkScalarACos(val) (float)sk_float_acos(val)
49 #define SkScalarATan2(y, x) (float)sk_float_atan2(y,x)
50 #define SkScalarExp(x) (float)sk_float_exp(x)
51 #define SkScalarLog(x) (float)sk_float_log(x)
52 #define SkScalarLog2(x) (float)sk_float_log2(x)
53 
55 
56 #define SkIntToScalar(x) static_cast<SkScalar>(x)
57 #define SkIntToFloat(x) static_cast<float>(x)
58 #define SkScalarTruncToInt(x) static_cast<int>(x)
59 
60 #define SkScalarToFloat(x) static_cast<float>(x)
61 #define SkFloatToScalar(x) static_cast<SkScalar>(x)
62 #define SkScalarToDouble(x) static_cast<double>(x)
63 #define SkDoubleToScalar(x) static_cast<SkScalar>(x)
64 
65 #define SK_ScalarMin (-SK_ScalarMax)
66 
67 static inline bool SkScalarIsNaN(SkScalar x) { return x != x; }
68 
71 static inline bool SkScalarIsFinite(SkScalar x) {
72  // We rely on the following behavior of infinities and nans
73  // 0 * finite --> 0
74  // 0 * infinity --> NaN
75  // 0 * NaN --> NaN
76  SkScalar prod = x * 0;
77  // At this point, prod will either be NaN or 0
78  return !SkScalarIsNaN(prod);
79 }
80 
81 static inline bool SkScalarsAreFinite(SkScalar a, SkScalar b) {
82  SkScalar prod = 0;
83  prod *= a;
84  prod *= b;
85  // At this point, prod will either be NaN or 0
86  return !SkScalarIsNaN(prod);
87 }
88 
89 static inline bool SkScalarsAreFinite(const SkScalar array[], int count) {
90  SkScalar prod = 0;
91  for (int i = 0; i < count; ++i) {
92  prod *= array[i];
93  }
94  // At this point, prod will either be NaN or 0
95  return !SkScalarIsNaN(prod);
96 }
97 
112 static inline int SkDScalarRoundToInt(SkScalar x) {
113  double xx = x;
114  xx += 0.5;
115  return (int)floor(xx);
116 }
117 
119 static inline SkScalar SkScalarFraction(SkScalar x) {
120  return x - SkScalarTruncToScalar(x);
121 }
122 
123 static inline SkScalar SkScalarClampMax(SkScalar x, SkScalar max) {
124  x = SkTMin(x, max);
125  x = SkTMax<SkScalar>(x, 0);
126  return x;
127 }
128 
129 static inline SkScalar SkScalarPin(SkScalar x, SkScalar min, SkScalar max) {
130  return SkTPin(x, min, max);
131 }
132 
133 SkScalar SkScalarSinCos(SkScalar radians, SkScalar* cosValue);
134 
135 static inline SkScalar SkScalarSquare(SkScalar x) { return x * x; }
136 
137 #define SkScalarInvert(x) (SK_Scalar1 / (x))
138 #define SkScalarFastInvert(x) (SK_Scalar1 / (x))
139 #define SkScalarAve(a, b) (((a) + (b)) * SK_ScalarHalf)
140 #define SkScalarHalf(a) ((a) * SK_ScalarHalf)
141 
142 #define SkDegreesToRadians(degrees) ((degrees) * (SK_ScalarPI / 180))
143 #define SkRadiansToDegrees(radians) ((radians) * (180 / SK_ScalarPI))
144 
145 static inline SkScalar SkMaxScalar(SkScalar a, SkScalar b) { return a > b ? a : b; }
146 static inline SkScalar SkMinScalar(SkScalar a, SkScalar b) { return a < b ? a : b; }
147 
148 static inline bool SkScalarIsInt(SkScalar x) {
149  return x == (SkScalar)(int)x;
150 }
151 
158 static inline int SkScalarSignAsInt(SkScalar x) {
159  return x < 0 ? -1 : (x > 0);
160 }
161 
162 // Scalar result version of above
163 static inline SkScalar SkScalarSignAsScalar(SkScalar x) {
164  return x < 0 ? -SK_Scalar1 : ((x > 0) ? SK_Scalar1 : 0);
165 }
166 
167 #define SK_ScalarNearlyZero (SK_Scalar1 / (1 << 12))
168 
169 static inline bool SkScalarNearlyZero(SkScalar x,
170  SkScalar tolerance = SK_ScalarNearlyZero) {
171  SkASSERT(tolerance >= 0);
172  return SkScalarAbs(x) <= tolerance;
173 }
174 
175 static inline bool SkScalarNearlyEqual(SkScalar x, SkScalar y,
176  SkScalar tolerance = SK_ScalarNearlyZero) {
177  SkASSERT(tolerance >= 0);
178  return SkScalarAbs(x-y) <= tolerance;
179 }
180 
187 static inline SkScalar SkScalarInterp(SkScalar A, SkScalar B, SkScalar t) {
188  SkASSERT(t >= 0 && t <= SK_Scalar1);
189  return A + (B - A) * t;
190 }
191 
202 SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],
203  const SkScalar values[], int length);
204 
205 /*
206  * Helper to compare an array of scalars.
207  */
208 static inline bool SkScalarsEqual(const SkScalar a[], const SkScalar b[], int n) {
209  SkASSERT(n >= 0);
210  for (int i = 0; i < n; ++i) {
211  if (a[i] != b[i]) {
212  return false;
213  }
214  }
215  return true;
216 }
217 
218 #endif