Templatize SkPMFloat to support both 1 and 255 biases.

src/opts/SkPMFloat_none.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 namespace {  // See SkPMFloat.h
 
-inline SkPMFloat::SkPMFloat(SkPMColor c) {
-    float inv255 = 1.0f/255;
-    *this = SkPMFloat::FromARGB(SkGetPackedA32(c) * inv255,
-                                SkGetPackedR32(c) * inv255,
-                                SkGetPackedG32(c) * inv255,
-                                SkGetPackedB32(c) * inv255);
+template <int kBias>
+inline SkPMFloat<kBias>::SkPMFloat(SkPMColor c) {
+    float scale = (kBias == 1) ? (1.0f/255) : 1;
+    *this = SkPMFloat::FromARGB(SkGetPackedA32(c) * scale,
+                                SkGetPackedR32(c) * scale,
+                                SkGetPackedG32(c) * scale,
+                                SkGetPackedB32(c) * scale);
     SkASSERT(this->isValid());
 }
 
-inline SkPMColor SkPMFloat::round() const {
+template <int kBias>
+inline SkPMColor SkPMFloat<kBias>::round() const {
+    float scale = (kBias == 1) ? 255 : 1;
     float a = this->a(),
           r = this->r(),
           g = this->g(),
           b = this->b();
     a = a < 0 ? 0 : (a > 1 ? 1 : a);
     r = r < 0 ? 0 : (r > 1 ? 1 : r);
     g = g < 0 ? 0 : (g > 1 ? 1 : g);
     b = b < 0 ? 0 : (b > 1 ? 1 : b);
-    SkPMColor c = SkPackARGB32(255*a+0.5f, 255*r+0.5f, 255*g+0.5f, 255*b+0.5f);
+    SkPMColor c = SkPackARGB32(scale*a+0.5f, scale*r+0.5f, scale*g+0.5f, scale*b+0.5f);
     SkPMColorAssert(c);
     return c;
 }
 
-inline Sk4f SkPMFloat::alphas() const {
+template <int kBias>
+inline Sk4f SkPMFloat<kBias>::alphas() const {
     return Sk4f(this->a());
 }
 
-inline SkPMFloat SkPMFloat::FromOpaqueColor(SkColor c) {
+template <int kBias>
+inline SkPMFloat<kBias> SkPMFloat<kBias>::FromOpaqueColor(SkColor c) {
   SkASSERT(SkColorGetA(c) == 0xFF);
-  float inv255 = 1.0f / 255;
-  SkPMFloat pmf = SkPMFloat::FromARGB(1.0f,
-                                      SkColorGetR(c) * inv255,
-                                      SkColorGetG(c) * inv255,
-                                      SkColorGetB(c) * inv255);
+  float scale = (kBias == 1) ? (1.0f/255) : 1;
+  SkPMFloat pmf = SkPMFloat::FromARGB(kBias,
+                                      SkColorGetR(c) * scale,
+                                      SkColorGetG(c) * scale,
+                                      SkColorGetB(c) * scale);
   SkASSERT(pmf.isValid());
   return pmf;
 }
 
 }  // namespace