4-at-a-time SkPMColor -> SkPMFloat API.

tests/PMFloatTest.cpp

 #include "SkPMFloat.h"
 #include "Test.h"
 
 DEF_TEST(SkPMFloat, r) {
     // Test SkPMColor <-> SkPMFloat
     SkPMColor c = SkPreMultiplyColor(0xFFCC9933);
     SkPMFloat pmf(c);
     REPORTER_ASSERT(r, SkScalarNearlyEqual(255.0f, pmf.a()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual(204.0f, pmf.r()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual(153.0f, pmf.g()));
@@ skipping 11 matching lines @@
     REPORTER_ASSERT(r, SkScalarNearlyEqual(  1.0f, clamped.g()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual(  0.0f, clamped.b()));
 
     // Test SkPMFloat <-> Sk4f conversion.
     Sk4f fs = clamped;
     SkPMFloat scaled = fs.multiply(0.25f);
     REPORTER_ASSERT(r, SkScalarNearlyEqual(63.75f, scaled.a()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual(38.25f, scaled.r()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual( 0.25f, scaled.g()));
     REPORTER_ASSERT(r, SkScalarNearlyEqual( 0.00f, scaled.b()));
+
+    // Test 4-at-a-time conversions.
+    SkPMColor colors[4] = { 0xFF000000, 0xFFFF0000, 0xFF00FF00, 0xFF0000FF };
+    SkPMFloat floats[4];
+    SkPMFloat::From4PMColors(floats, colors);
+
+    SkPMColor back[4];
+    SkPMFloat::To4PMColors(back, floats);
+    for (int i = 0; i < 4; i++) {
+        REPORTER_ASSERT(r, back[i] == colors[i]);
+    }
+
+    SkPMFloat::ClampTo4PMColors(back, floats);
+    for (int i = 0; i < 4; i++) {
+        REPORTER_ASSERT(r, back[i] == colors[i]);
+    }
 }