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| 1 /* |
| 2 * Copyright 2015 Google Inc. |
| 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 SkPx_DEFINED |
| 9 #define SkPx_DEFINED |
| 10 |
| 11 #include "SkTypes.h" |
| 12 #include "SkColorPriv.h" |
| 13 |
| 14 // We'll include one of src/opts/SkPx_{sse,neon,none}.h to define a type SkPx. |
| 15 // |
| 16 // SkPx represents up to SkPx::N 8888 pixels. It's agnostic to whether these |
| 17 // are SkColors or SkPMColors; it only assumes that alpha is the high byte. |
| 18 static_assert(SK_A32_SHIFT == 24, "For both SkColor and SkPMColor, alpha is alwa
ys the high byte."); |
| 19 // |
| 20 // SkPx::Alpha represents up to SkPx::N 8-bit values, usually coverage or alpha. |
| 21 // SkPx::Wide represents up to SkPx::N pixels with 16 bits per component. |
| 22 // |
| 23 // SkPx supports the following methods: |
| 24 // static SkPx Dup(uint32_t); |
| 25 // static SkPx Load(const uint32_t*); |
| 26 // static SkPx Load(const uint32_t*, int n); // where 0<n<SkPx::N |
| 27 // void store(uint32_t*) const; |
| 28 // void store(uint32_t*, int n) const; // where 0<n<SkPx::N |
| 29 // |
| 30 // Alpha alpha() const; // argb -> a |
| 31 // Wide widenLo() const; // argb -> 0a0r0g0b |
| 32 // Wide widenHi() const; // argb -> a0r0g0b0 |
| 33 // Wide widenLoHi() const; // argb -> aarrggbb |
| 34 // |
| 35 // SkPx operator+(const SkPx&) const; |
| 36 // SkPx operator-(const SkPx&) const; |
| 37 // SkPx saturatedAdd(const SkPx&) const; |
| 38 // |
| 39 // Wide operator*(const Alpha&) const; // argb * A -> (a*A)(r*A)(g*A)(b*A) |
| 40 // |
| 41 // // Fast approximate (px*a+127)/255. |
| 42 // // Never off by more than 1, and always correct when px or a is 0 or 255. |
| 43 // // We use the approximation (px*a+px)/256. |
| 44 // SkPx approxMulDiv255(const Alpha&) const; |
| 45 // |
| 46 // SkPx addAlpha(const Alpha&) const; // argb + A -> (a+A)rgb |
| 47 // |
| 48 // SkPx::Alpha supports the following methods: |
| 49 // static Alpha Dup(uint8_t); |
| 50 // static Alpha Load(const uint8_t*); |
| 51 // static Alpha Load(const uint8_t*, int n); // where 0<n<SkPx::N |
| 52 // |
| 53 // Alpha inv() const; // a -> 255-a |
| 54 // |
| 55 // SkPx::Wide supports the following methods: |
| 56 // Wide operator+(const Wide&); |
| 57 // Wide operator-(const Wide&); |
| 58 // Wide shl<int bits>(); |
| 59 // Wide shr<int bits>(); |
| 60 // |
| 61 // // Return the high byte of each component of (*this + o.widenLo()). |
| 62 // SkPx addNarrowHi(const SkPx& o); |
| 63 // |
| 64 // Methods left unwritten, but certainly to come: |
| 65 // SkPx SkPx::operator<(const SkPx&) const; |
| 66 // SkPx SkPx::thenElse(const SkPx& then, const SkPx& else) const; |
| 67 // Wide Wide::operator<(const Wide&) const; |
| 68 // Wide Wide::thenElse(const Wide& then, const Wide& else) const; |
| 69 // |
| 70 // SkPx Wide::div255() const; // Rounds, think (*this + 127) / 255. |
| 71 // |
| 72 // The different implementations of SkPx have complete freedom to choose |
| 73 // SkPx::N and how they represent SkPx, SkPx::Alpha, and SkPx::Wide. |
| 74 // |
| 75 // All observable math must remain identical. |
| 76 |
| 77 #if defined(SKNX_NO_SIMD) |
| 78 #include "../opts/SkPx_none.h" |
| 79 #else |
| 80 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 |
| 81 #include "../opts/SkPx_sse.h" |
| 82 #elif defined(SK_ARM_HAS_NEON) |
| 83 #include "../opts/SkPx_neon.h" |
| 84 #else |
| 85 #include "../opts/SkPx_none.h" |
| 86 #endif |
| 87 #endif |
| 88 |
| 89 #endif//SkPx_DEFINED |
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