Convert SkPMFloat to [0,1] range and prune its API.

src/opts/SkPMFloat_none.h

Index: src/opts/SkPMFloat_none.h
diff --git a/src/opts/SkPMFloat_none.h b/src/opts/SkPMFloat_none.h
index 9bb584ed8646a43f0978e8955f23450562d5fc23..ba773564d6de9cf89d84c5f80856ec7a5c021d60 100644
--- a/src/opts/SkPMFloat_none.h
+++ b/src/opts/SkPMFloat_none.h
@@ -8,61 +8,26 @@
 namespace {  // See SkPMFloat.h
 
 inline SkPMFloat::SkPMFloat(SkPMColor c) {
-    *this = SkPMFloat::FromARGB(SkGetPackedA32(c),
-                                SkGetPackedR32(c),
-                                SkGetPackedG32(c),
-                                SkGetPackedB32(c));
+    float inv255 = 1.0f/255;
+    *this = SkPMFloat::FromARGB(SkGetPackedA32(c) * inv255,
+                                SkGetPackedR32(c) * inv255,
+                                SkGetPackedG32(c) * inv255,
+                                SkGetPackedB32(c) * inv255);
     SkASSERT(this->isValid());
 }
 
-inline SkPMColor SkPMFloat::trunc() const {
-    return SkPackARGB32(this->a(), this->r(), this->g(), this->b());
-}
-
 inline SkPMColor SkPMFloat::round() const {
-    SkPMColor c = SkPackARGB32(this->a()+0.5f, this->r()+0.5f, this->g()+0.5f, this->b()+0.5f);
-    SkPMColorAssert(c);
-    return c;
-}
-
-inline SkPMColor SkPMFloat::roundClamp() const {
     float a = this->a(),
           r = this->r(),
           g = this->g(),
           b = this->b();
-    a = a < 0 ? 0 : (a > 255 ? 255 : a);
-    r = r < 0 ? 0 : (r > 255 ? 255 : r);
-    g = g < 0 ? 0 : (g > 255 ? 255 : g);
-    b = b < 0 ? 0 : (b > 255 ? 255 : b);
-    SkPMColor c = SkPackARGB32(a+0.5f, r+0.5f, g+0.5f, b+0.5f);
+    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);
     SkPMColorAssert(c);
     return c;
 }
 
-inline void SkPMFloat::From4PMColors(const SkPMColor colors[4],
-                                     SkPMFloat* a, SkPMFloat* b, SkPMFloat* c, SkPMFloat* d) {
-    *a = FromPMColor(colors[0]);
-    *b = FromPMColor(colors[1]);
-    *c = FromPMColor(colors[2]);
-    *d = FromPMColor(colors[3]);
-}
-
-inline void SkPMFloat::RoundTo4PMColors(
-        const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
-        SkPMColor colors[4]) {
-    colors[0] = a.round();
-    colors[1] = b.round();
-    colors[2] = c.round();
-    colors[3] = d.round();
-}
-
-inline void SkPMFloat::RoundClampTo4PMColors(
-        const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
-        SkPMColor colors[4]) {
-    colors[0] = a.roundClamp();
-    colors[1] = b.roundClamp();
-    colors[2] = c.roundClamp();
-    colors[3] = d.roundClamp();
-}
-
 }  // namespace