float components in xfermodes

src/core/SkPM4fPriv.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorPriv.h"
 #include "SkNx.h"
 
 static inline float get_alpha(const Sk4f& f4) {
     return f4.kth<SkPM4f::A>();
 }
 
 static inline Sk4f set_alpha(const Sk4f& f4, float alpha) {
     static_assert(3 == SkPM4f::A, "");
     return Sk4f(f4.kth<0>(), f4.kth<1>(), f4.kth<2>(), alpha);
 }
 
 static inline uint32_t to_4b(const Sk4f& f4) {
     uint32_t b4;
     SkNx_cast<uint8_t>(f4).store((uint8_t*)&b4);
     return b4;
 }
 
 static inline Sk4f to_4f(uint32_t b4) {
     return SkNx_cast<float>(Sk4b::Load((const uint8_t*)&b4));
 }
 
-static inline Sk4f s2l(const Sk4f& s4) {
+static inline Sk4f srgb_to_linear(const Sk4f& s4) {
     return set_alpha(s4 * s4, get_alpha(s4));
 }
 
-static inline Sk4f l2s(const Sk4f& l4) {
-    return set_alpha(l4.rsqrt1() * l4, get_alpha(l4));
+static inline Sk4f linear_to_srgb(const Sk4f& l4) {
+    return set_alpha(l4.sqrt(), get_alpha(l4));
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 static inline Sk4f Sk4f_fromL32(uint32_t src) {
     return to_4f(src) * Sk4f(1.0f/255);
 }
 
 static inline Sk4f Sk4f_fromS32(uint32_t src) {
-    return s2l(to_4f(src) * Sk4f(1.0f/255));
+    return srgb_to_linear(to_4f(src) * Sk4f(1.0f/255));
 }
 
 static inline uint32_t Sk4f_toL32(const Sk4f& x4) {
     return to_4b(x4 * Sk4f(255) + Sk4f(0.5f));
 }
 
 static inline uint32_t Sk4f_toS32(const Sk4f& x4) {
-    return to_4b(l2s(x4) * Sk4f(255) + Sk4f(0.5f));
+    return to_4b(linear_to_srgb(x4) * Sk4f(255) + Sk4f(0.5f));
 }
-
-///////////////////////////////////////////////////////////////////////////////////////////////////
-
-static Sk4f unit_to_l255_round(const SkPM4f& pm4) {
-    return Sk4f::Load(pm4.fVec) * Sk4f(255) + Sk4f(0.5f);
-}
-
-static Sk4f unit_to_s255_round(const SkPM4f& pm4) {
-    return l2s(Sk4f::Load(pm4.fVec)) * Sk4f(255) + Sk4f(0.5f);
-}
-
-static inline void SkPM4f_l32_src_mode(SkPMColor dst[], const SkPM4f src[], int count) {
-    for (int i = 0; i < (count >> 2); ++i) {
-        SkASSERT(src[0].isUnit());
-        SkASSERT(src[1].isUnit());
-        SkASSERT(src[2].isUnit());
-        SkASSERT(src[3].isUnit());
-        Sk4f_ToBytes((uint8_t*)dst,
-                     unit_to_l255_round(src[0]), unit_to_l255_round(src[1]),
-                     unit_to_l255_round(src[2]), unit_to_l255_round(src[3]));
-        src += 4;
-        dst += 4;
-    }
-    count &= 3;
-    for (int i = 0; i < count; ++i) {
-        SkASSERT(src[i].isUnit());
-        SkNx_cast<uint8_t>(unit_to_l255_round(src[i])).store((uint8_t*)&dst[i]);
-    }
-}
-
-static inline void SkPM4f_l32_srcover_mode(SkPMColor dst[], const SkPM4f src[], int count) {
-    for (int i = 0; i < count; ++i) {
-        SkASSERT(src[i].isUnit());
-        Sk4f s4 = Sk4f::Load(src[i].fVec);
-        Sk4f d4 = Sk4f_fromL32(dst[i]);
-        dst[i] = Sk4f_toL32(s4 + d4 * Sk4f(1 - get_alpha(s4)));
-    }
-}
-
-static inline void SkPM4f_s32_src_mode(SkPMColor dst[], const SkPM4f src[], int count) {
-    for (int i = 0; i < (count >> 2); ++i) {
-        SkASSERT(src[0].isUnit());
-        SkASSERT(src[1].isUnit());
-        SkASSERT(src[2].isUnit());
-        SkASSERT(src[3].isUnit());
-        Sk4f_ToBytes((uint8_t*)dst,
-                     unit_to_s255_round(src[0]), unit_to_s255_round(src[1]),
-                     unit_to_s255_round(src[2]), unit_to_s255_round(src[3]));
-        src += 4;
-        dst += 4;
-    }
-    count &= 3;
-    for (int i = 0; i < count; ++i) {
-        SkASSERT(src[i].isUnit());
-        SkNx_cast<uint8_t>(unit_to_s255_round(src[i])).store((uint8_t*)&dst[i]);
-    }
-}
-
-static inline void SkPM4f_s32_srcover_mode(SkPMColor dst[], const SkPM4f src[], int count) {
-    for (int i = 0; i < count; ++i) {
-        SkASSERT(src[i].isUnit());
-        Sk4f s4 = Sk4f::Load(src[i].fVec);
-        Sk4f d4 = Sk4f_fromS32(dst[i]);
-        dst[i] = Sk4f_toS32(s4 + d4 * Sk4f(1 - get_alpha(s4)));
-    }
-}
-