Add bitmap manipulation functions in advance of themes.

skia/ext/skia_utils_unittest.cc

+// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <stdlib.h>
+
+#include "skia/ext/skia_utils.h"
+#include "skia/include/SkColorPriv.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "SkBitmap.h"
+
+TEST(SkiaUtils, SkColorToHSLRed) {
+  SkColor red = SkColorSetARGB(255, 255, 0, 0);
+  SkScalar hsl[3];
+  skia::SkColorToHSL(red, hsl);
+  EXPECT_EQ(hsl[0], 0);
+  EXPECT_EQ(hsl[1], 1);
+  EXPECT_EQ(hsl[2], 0.5);
+}
+
+TEST(SkiaUtils, SkColorToHSLGrey) {
+  SkColor red = SkColorSetARGB(255, 128, 128, 128);
+  SkScalar hsl[3];
+  skia::SkColorToHSL(red, hsl);
+  EXPECT_EQ(hsl[0], 0);
+  EXPECT_EQ(hsl[1], 0);
+  EXPECT_EQ(static_cast<int>(hsl[2] * 100),
+            static_cast<int>(0.5 * 100));  // Accurate to two decimal places.
+}
+
+TEST(SkiaUtils, HSLToSkColorWithAlpha) {
+  // Premultiplied alpha - this is full red.
+  SkColor red = SkColorSetARGB(128, 128, 0, 0);
+
+  SkScalar hsl[3] = {
+      SkDoubleToScalar(0),
+      SkDoubleToScalar(1),
+      SkDoubleToScalar(0.5),
+  };
+
+  SkColor result = skia::HSLToSKColor(128, hsl);
+  EXPECT_EQ(SkColorGetA(red), SkColorGetA(result));
+  EXPECT_EQ(SkColorGetR(red), SkColorGetR(result));
+  EXPECT_EQ(SkColorGetG(red), SkColorGetG(result));
+  EXPECT_EQ(SkColorGetB(red), SkColorGetB(result));
+}
+