make SkPM4f private

src/core/SkPM4f.h

Index: src/core/SkPM4f.h
diff --git a/src/core/SkPM4f.h b/src/core/SkPM4f.h
new file mode 100644
index 0000000000000000000000000000000000000000..fb22783dcc44203a8c3931982f645e3de7dde956
--- /dev/null
+++ b/src/core/SkPM4f.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkPM4f_DEFINED
+#define SkPM4f_DEFINED
+
+#include "SkColorPriv.h"
+
+/*
+ *  The float values are 0...1 premultiplied
+ */
+struct SkPM4f {
+    enum {
+        A = SK_A32_SHIFT/8,
+        R = SK_R32_SHIFT/8,
+        G = SK_G32_SHIFT/8,
+        B = SK_B32_SHIFT/8,
+    };
+    float fVec[4];
+
+    float a() const { return fVec[A]; }
+
+    SkColor4f unpremul() const;
+
+    static SkPM4f FromPMColor(SkPMColor);
+
+    // half-float routines
+    void toF16(uint16_t[4]) const;
+    uint64_t toF16() const; // 4 float16 values packed into uint64_t
+    static SkPM4f FromF16(const uint16_t[4]);
+
+#ifdef SK_DEBUG
+    void assertIsUnit() const;
+#else
+    void assertIsUnit() const {}
+#endif
+};
+
+typedef SkPM4f (*SkXfermodeProc4f)(const SkPM4f& src, const SkPM4f& dst);
+
+
+#endif