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 /* * Copyright 2016 Google Inc. * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #ifndef SkColorSpaceXformPriv_DEFINED #define SkColorSpaceXformPriv_DEFINED #include "SkColorSpaceXform.h" #include "SkHalf.h" #include "SkSRGB.h" #define SkCSXformPrintfDefined 0 #define SkCSXformPrintf(...) // Interpolating lookup in a variably sized table. static inline float interp_lut(float input, const float* table, int tableSize) { float index = input * (tableSize - 1); float diff = index - sk_float_floor2int(index); return table[(int) sk_float_floor2int(index)] * (1.0f - diff) + table[(int) sk_float_ceil2int(index)] * diff; } // Expand range from 0-1 to 0-255, then convert. static inline uint8_t clamp_normalized_float_to_byte(float v) { // The ordering of the logic is a little strange here in order // to make sure we convert NaNs to 0. v = v * 255.0f; if (v >= 254.5f) { return 255; } else if (v >= 0.5f) { return (uint8_t) (v + 0.5f); } else { return 0; } } static inline float clamp_0_1(float v) { // The ordering of the logic is a little strange here in order // to make sure we convert NaNs to 0. if (v >= 1.0f) { return 1.0f; } else if (v >= 0.0f) { return v; } else { return 0.0f; } } /** * Invert table lookup. Ex: what indices corresponds to the input values? * This will have strange results when the table is not increasing. * But any sane gamma function will be increasing. * @param outTableFloat Destination table for float (0-1) results. Can be nullptr if not wanted. * @param outTableByte Destination table for byte (0-255) results. Can be nullptr if not wanted. * @param outTableSize Number of elements in |outTableFloat| or |outTableBytes| * @param inTable The source table to invert * @param inTableSize The number of elements in |inTable| */ static inline void invert_table_gamma(float* outTableFloat, uint8_t* outTableByte, int outTableSize, const float* inTable, int inTableSize) { // should never have a gamma table this small anyway, 0/1 are either not allowed // or imply a non-table gamma such as linear/exponential SkASSERT(inTableSize >= 2); int inIndex = 1; for (int outIndex = 0; outIndex < outTableSize; ++outIndex) { const float input = outIndex / (outTableSize - 1.0f); while (inIndex < inTableSize - 1 && inTable[inIndex] < input) { ++inIndex; } const float diff = input - inTable[inIndex - 1]; const float distance = inTable[inIndex] - inTable[inIndex - 1]; const float normalizedIndex = (inIndex - 1) + diff / distance; const float index = normalizedIndex / (inTableSize - 1); if (outTableByte) { outTableByte[outIndex] = clamp_normalized_float_to_byte(index); } if (outTableFloat) { outTableFloat[outIndex] = clamp_0_1(index); } } } static inline SkColorSpaceXform::ColorFormat select_xform_format(SkColorType colorType) { switch (colorType) { case kRGBA_8888_SkColorType: return SkColorSpaceXform::kRGBA_8888_ColorFormat; case kBGRA_8888_SkColorType: return SkColorSpaceXform::kBGRA_8888_ColorFormat; case kRGBA_F16_SkColorType: return SkColorSpaceXform::kRGBA_F16_ColorFormat; case kRGB_565_SkColorType: return SkColorSpaceXform::kBGR_565_ColorFormat; default: SkASSERT(false); return SkColorSpaceXform::kRGBA_8888_ColorFormat; } } #endif