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Diffstat (limited to 'core/SkScalar.h')
| -rw-r--r-- | core/SkScalar.h | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/core/SkScalar.h b/core/SkScalar.h new file mode 100644 index 0000000..2dd7a62 --- /dev/null +++ b/core/SkScalar.h @@ -0,0 +1,341 @@ + +/* + * Copyright 2006 The Android Open Source Project + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + + +#ifndef SkScalar_DEFINED +#define SkScalar_DEFINED + +#include "SkFixed.h" +#include "SkFloatingPoint.h" + +/** \file SkScalar.h + + Types and macros for the data type SkScalar. This is the fractional numeric type + that, depending on the compile-time flag SK_SCALAR_IS_FLOAT, may be implemented + either as an IEEE float, or as a 16.16 SkFixed. The macros in this file are written + to allow the calling code to manipulate SkScalar values without knowing which representation + is in effect. +*/ + +#ifdef SK_SCALAR_IS_FLOAT + + /** SkScalar is our type for fractional values and coordinates. Depending on + compile configurations, it is either represented as an IEEE float, or + as a 16.16 fixed point integer. + */ + typedef float SkScalar; + + /** SK_Scalar1 is defined to be 1.0 represented as an SkScalar + */ + #define SK_Scalar1 (1.0f) + /** SK_Scalar1 is defined to be 1/2 represented as an SkScalar + */ + #define SK_ScalarHalf (0.5f) + /** SK_ScalarInfinity is defined to be infinity as an SkScalar + */ + #define SK_ScalarInfinity SK_FloatInfinity + /** SK_ScalarNegativeInfinity is defined to be negative infinity as an SkScalar + */ + #define SK_ScalarNegativeInfinity SK_FloatNegativeInfinity + /** SK_ScalarMax is defined to be the largest value representable as an SkScalar + */ + #define SK_ScalarMax (3.402823466e+38f) + /** SK_ScalarMin is defined to be the smallest value representable as an SkScalar + */ + #define SK_ScalarMin (-SK_ScalarMax) + /** SK_ScalarNaN is defined to be 'Not a Number' as an SkScalar + */ + #define SK_ScalarNaN SK_FloatNaN + /** SkScalarIsNaN(n) returns true if argument is not a number + */ + static inline bool SkScalarIsNaN(float x) { return x != x; } + + /** Returns true if x is not NaN and not infinite */ + static inline bool SkScalarIsFinite(float x) { + // We rely on the following behavior of infinities and nans + // 0 * finite --> 0 + // 0 * infinity --> NaN + // 0 * NaN --> NaN + float prod = x * 0; + // At this point, prod will either be NaN or 0 + // Therefore we can return (prod == prod) or (0 == prod). + return prod == prod; + } + + /** SkIntToScalar(n) returns its integer argument as an SkScalar + */ + #define SkIntToScalar(n) ((float)(n)) + /** SkFixedToScalar(n) returns its SkFixed argument as an SkScalar + */ + #define SkFixedToScalar(x) SkFixedToFloat(x) + /** SkScalarToFixed(n) returns its SkScalar argument as an SkFixed + */ + #define SkScalarToFixed(x) SkFloatToFixed(x) + + #define SkScalarToFloat(n) (n) + #define SkFloatToScalar(n) (n) + + #define SkScalarToDouble(n) (double)(n) + #define SkDoubleToScalar(n) (float)(n) + + /** SkScalarFraction(x) returns the signed fractional part of the argument + */ + #define SkScalarFraction(x) sk_float_mod(x, 1.0f) + + #define SkScalarFloorToScalar(x) sk_float_floor(x) + #define SkScalarCeilToScalar(x) sk_float_ceil(x) + #define SkScalarRoundToScalar(x) sk_float_floor((x) + 0.5f) + + #define SkScalarFloorToInt(x) sk_float_floor2int(x) + #define SkScalarCeilToInt(x) sk_float_ceil2int(x) + #define SkScalarRoundToInt(x) sk_float_round2int(x) + #define SkScalarTruncToInt(x) static_cast<int>(x) + + /** Returns the absolute value of the specified SkScalar + */ + #define SkScalarAbs(x) sk_float_abs(x) + /** Return x with the sign of y + */ + #define SkScalarCopySign(x, y) sk_float_copysign(x, y) + /** Returns the value pinned between 0 and max inclusive + */ + inline SkScalar SkScalarClampMax(SkScalar x, SkScalar max) { + return x < 0 ? 0 : x > max ? max : x; + } + /** Returns the value pinned between min and max inclusive + */ + inline SkScalar SkScalarPin(SkScalar x, SkScalar min, SkScalar max) { + return x < min ? min : x > max ? max : x; + } + /** Returns the specified SkScalar squared (x*x) + */ + inline SkScalar SkScalarSquare(SkScalar x) { return x * x; } + /** Returns the product of two SkScalars + */ + #define SkScalarMul(a, b) ((float)(a) * (b)) + /** Returns the product of two SkScalars plus a third SkScalar + */ + #define SkScalarMulAdd(a, b, c) ((float)(a) * (b) + (c)) + /** Returns the product of a SkScalar and an int rounded to the nearest integer value + */ + #define SkScalarMulRound(a, b) SkScalarRound((float)(a) * (b)) + /** Returns the product of a SkScalar and an int promoted to the next larger int + */ + #define SkScalarMulCeil(a, b) SkScalarCeil((float)(a) * (b)) + /** Returns the product of a SkScalar and an int truncated to the next smaller int + */ + #define SkScalarMulFloor(a, b) SkScalarFloor((float)(a) * (b)) + /** Returns the quotient of two SkScalars (a/b) + */ + #define SkScalarDiv(a, b) ((float)(a) / (b)) + /** Returns the mod of two SkScalars (a mod b) + */ + #define SkScalarMod(x,y) sk_float_mod(x,y) + /** Returns the product of the first two arguments, divided by the third argument + */ + #define SkScalarMulDiv(a, b, c) ((float)(a) * (b) / (c)) + /** Returns the multiplicative inverse of the SkScalar (1/x) + */ + #define SkScalarInvert(x) (SK_Scalar1 / (x)) + #define SkScalarFastInvert(x) (SK_Scalar1 / (x)) + /** Returns the square root of the SkScalar + */ + #define SkScalarSqrt(x) sk_float_sqrt(x) + /** Returns b to the e + */ + #define SkScalarPow(b, e) sk_float_pow(b, e) + /** Returns the average of two SkScalars (a+b)/2 + */ + #define SkScalarAve(a, b) (((a) + (b)) * 0.5f) + /** Returns the geometric mean of two SkScalars + */ + #define SkScalarMean(a, b) sk_float_sqrt((float)(a) * (b)) + /** Returns one half of the specified SkScalar + */ + #define SkScalarHalf(a) ((a) * 0.5f) + + #define SK_ScalarSqrt2 1.41421356f + #define SK_ScalarPI 3.14159265f + #define SK_ScalarTanPIOver8 0.414213562f + #define SK_ScalarRoot2Over2 0.707106781f + + #define SkDegreesToRadians(degrees) ((degrees) * (SK_ScalarPI / 180)) + float SkScalarSinCos(SkScalar radians, SkScalar* cosValue); + #define SkScalarSin(radians) (float)sk_float_sin(radians) + #define SkScalarCos(radians) (float)sk_float_cos(radians) + #define SkScalarTan(radians) (float)sk_float_tan(radians) + #define SkScalarASin(val) (float)sk_float_asin(val) + #define SkScalarACos(val) (float)sk_float_acos(val) + #define SkScalarATan2(y, x) (float)sk_float_atan2(y,x) + #define SkScalarExp(x) (float)sk_float_exp(x) + #define SkScalarLog(x) (float)sk_float_log(x) + + inline SkScalar SkMaxScalar(SkScalar a, SkScalar b) { return a > b ? a : b; } + inline SkScalar SkMinScalar(SkScalar a, SkScalar b) { return a < b ? a : b; } + + static inline bool SkScalarIsInt(SkScalar x) { + return x == (float)(int)x; + } +#else + typedef SkFixed SkScalar; + + #define SK_Scalar1 SK_Fixed1 + #define SK_ScalarHalf SK_FixedHalf + #define SK_ScalarInfinity SK_FixedMax + #define SK_ScalarNegativeInfinity SK_FixedMin + #define SK_ScalarMax SK_FixedMax + #define SK_ScalarMin SK_FixedMin + #define SK_ScalarNaN SK_FixedNaN + #define SkScalarIsNaN(x) ((x) == SK_FixedNaN) + #define SkScalarIsFinite(x) ((x) != SK_FixedNaN) + + #define SkIntToScalar(n) SkIntToFixed(n) + #define SkFixedToScalar(x) (x) + #define SkScalarToFixed(x) (x) + #define SkScalarToFloat(n) SkFixedToFloat(n) + #define SkFloatToScalar(n) SkFloatToFixed(n) + + #define SkScalarToDouble(n) SkFixedToDouble(n) + #define SkDoubleToScalar(n) SkDoubleToFixed(n) + #define SkScalarFraction(x) SkFixedFraction(x) + + #define SkScalarFloorToScalar(x) SkFixedFloorToFixed(x) + #define SkScalarCeilToScalar(x) SkFixedCeilToFixed(x) + #define SkScalarRoundToScalar(x) SkFixedRoundToFixed(x) + + #define SkScalarFloorToInt(x) SkFixedFloorToInt(x) + #define SkScalarCeilToInt(x) SkFixedCeilToInt(x) + #define SkScalarRoundToInt(x) SkFixedRoundToInt(x) + #define SkScalarTruncToInt(x) (((x) < 0) ? SkScalarCeilToInt(x) : SkScalarFloorToInt(x)) + + #define SkScalarAbs(x) SkFixedAbs(x) + #define SkScalarCopySign(x, y) SkCopySign32(x, y) + #define SkScalarClampMax(x, max) SkClampMax(x, max) + #define SkScalarPin(x, min, max) SkPin32(x, min, max) + #define SkScalarSquare(x) SkFixedSquare(x) + #define SkScalarMul(a, b) SkFixedMul(a, b) + #define SkScalarMulAdd(a, b, c) SkFixedMulAdd(a, b, c) + #define SkScalarMulRound(a, b) SkFixedMulCommon(a, b, SK_FixedHalf) + #define SkScalarMulCeil(a, b) SkFixedMulCommon(a, b, SK_Fixed1 - 1) + #define SkScalarMulFloor(a, b) SkFixedMulCommon(a, b, 0) + #define SkScalarDiv(a, b) SkFixedDiv(a, b) + #define SkScalarMod(a, b) SkFixedMod(a, b) + #define SkScalarMulDiv(a, b, c) SkMulDiv(a, b, c) + #define SkScalarInvert(x) SkFixedInvert(x) + #define SkScalarFastInvert(x) SkFixedFastInvert(x) + #define SkScalarSqrt(x) SkFixedSqrt(x) + #define SkScalarAve(a, b) SkFixedAve(a, b) + #define SkScalarMean(a, b) SkFixedMean(a, b) + #define SkScalarHalf(a) ((a) >> 1) + + #define SK_ScalarSqrt2 SK_FixedSqrt2 + #define SK_ScalarPI SK_FixedPI + #define SK_ScalarTanPIOver8 SK_FixedTanPIOver8 + #define SK_ScalarRoot2Over2 SK_FixedRoot2Over2 + + #define SkDegreesToRadians(degrees) SkFractMul(degrees, SK_FractPIOver180) + #define SkScalarSinCos(radians, cosPtr) SkFixedSinCos(radians, cosPtr) + #define SkScalarSin(radians) SkFixedSin(radians) + #define SkScalarCos(radians) SkFixedCos(radians) + #define SkScalarTan(val) SkFixedTan(val) + #define SkScalarASin(val) SkFixedASin(val) + #define SkScalarACos(val) SkFixedACos(val) + #define SkScalarATan2(y, x) SkFixedATan2(y,x) + #define SkScalarExp(x) SkFixedExp(x) + #define SkScalarLog(x) SkFixedLog(x) + + #define SkMaxScalar(a, b) SkMax32(a, b) + #define SkMinScalar(a, b) SkMin32(a, b) + + static inline bool SkScalarIsInt(SkFixed x) { + return 0 == (x & 0xffff); + } +#endif + +// DEPRECATED : use ToInt or ToScalar variant +#define SkScalarFloor(x) SkScalarFloorToInt(x) +#define SkScalarCeil(x) SkScalarCeilToInt(x) +#define SkScalarRound(x) SkScalarRoundToInt(x) + +/** + * Returns -1 || 0 || 1 depending on the sign of value: + * -1 if x < 0 + * 0 if x == 0 + * 1 if x > 0 + */ +static inline int SkScalarSignAsInt(SkScalar x) { + return x < 0 ? -1 : (x > 0); +} + +// Scalar result version of above +static inline SkScalar SkScalarSignAsScalar(SkScalar x) { + return x < 0 ? -SK_Scalar1 : ((x > 0) ? SK_Scalar1 : 0); +} + +#define SK_ScalarNearlyZero (SK_Scalar1 / (1 << 12)) + +static inline bool SkScalarNearlyZero(SkScalar x, + SkScalar tolerance = SK_ScalarNearlyZero) { + SkASSERT(tolerance >= 0); + return SkScalarAbs(x) <= tolerance; +} + +static inline bool SkScalarNearlyEqual(SkScalar x, SkScalar y, + SkScalar tolerance = SK_ScalarNearlyZero) { + SkASSERT(tolerance >= 0); + return SkScalarAbs(x-y) <= tolerance; +} + +/** Linearly interpolate between A and B, based on t. + If t is 0, return A + If t is 1, return B + else interpolate. + t must be [0..SK_Scalar1] +*/ +static inline SkScalar SkScalarInterp(SkScalar A, SkScalar B, SkScalar t) { + SkASSERT(t >= 0 && t <= SK_Scalar1); + return A + SkScalarMul(B - A, t); +} + +static inline SkScalar SkScalarLog2(SkScalar x) { + static const SkScalar log2_conversion_factor = SkScalarDiv(1, SkScalarLog(2)); + + return SkScalarMul(SkScalarLog(x), log2_conversion_factor); +} + +/** Interpolate along the function described by (keys[length], values[length]) + for the passed searchKey. SearchKeys outside the range keys[0]-keys[Length] + clamp to the min or max value. This function was inspired by a desire + to change the multiplier for thickness in fakeBold; therefore it assumes + the number of pairs (length) will be small, and a linear search is used. + Repeated keys are allowed for discontinuous functions (so long as keys is + monotonically increasing), and if key is the value of a repeated scalar in + keys, the first one will be used. However, that may change if a binary + search is used. +*/ +SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[], + const SkScalar values[], int length); + +/* + * Helper to compare an array of scalars. + */ +static inline bool SkScalarsEqual(const SkScalar a[], const SkScalar b[], int n) { +#ifdef SK_SCALAR_IS_FLOAT + SkASSERT(n >= 0); + for (int i = 0; i < n; ++i) { + if (a[i] != b[i]) { + return false; + } + } + return true; +#else + return 0 == memcmp(a, b, n * sizeof(SkScalar)); +#endif +} + +#endif |