Towards deleting YUV to RGB computation redundancy

ui/gfx/color_space_unittest.cc

+// Copyright 2017 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 <cmath>
+
+#include "base/logging.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/color_space.h"
+
+namespace gfx {
+namespace {
+
+const float kEpsilon = 1.0e-3f;
+
+// Returns the L-infty difference of u and v.
+float Diff(const SkVector4& u, const SkVector4& v) {
+  float result = 0;
+  for (size_t i = 0; i < 4; ++i)
+    result = std::max(result, std::abs(u.fData[i] - v.fData[i]));
+  return result;
+}
+
+TEST(ColorSpace, RGBToYUV) {
+  const size_t kNumTestRGBs = 3;
+  SkVector4 test_rgbs[kNumTestRGBs] = {
+      SkVector4(1.f, 0.f, 0.f, 1.f),
+      SkVector4(0.f, 1.f, 0.f, 1.f),
+      SkVector4(0.f, 0.f, 1.f, 1.f),
+  };
+
+  const size_t kNumColorSpaces = 4;
+  gfx::ColorSpace color_spaces[kNumColorSpaces] = {
+      gfx::ColorSpace::CreateREC601(), gfx::ColorSpace::CreateREC709(),
+      gfx::ColorSpace::CreateJpeg(), gfx::ColorSpace::CreateXYZD50(),
+  };
+
+  SkVector4 expected_yuvs[kNumColorSpaces][kNumTestRGBs] = {
+      // REC601
+      {
+          SkVector4(0.3195f, 0.3518f, 0.9392f, 1.0000f),
+          SkVector4(0.5669f, 0.2090f, 0.1322f, 1.0000f),
+          SkVector4(0.1607f, 0.9392f, 0.4286f, 1.0000f),
+      },
+      // REC709
+      {
+          SkVector4(0.2453f, 0.3994f, 0.9392f, 1.0000f),
+          SkVector4(0.6770f, 0.1614f, 0.1011f, 1.0000f),
+          SkVector4(0.1248f, 0.9392f, 0.4597f, 1.0000f),
+      },
+      // Jpeg
+      {
+          SkVector4(0.2990f, 0.3313f, 1.0000f, 1.0000f),
+          SkVector4(0.5870f, 0.1687f, 0.0813f, 1.0000f),
+          SkVector4(0.1140f, 1.0000f, 0.4187f, 1.0000f),
+      },
+      // XYZD50
+      {
+          SkVector4(1.0000f, 0.0000f, 0.0000f, 1.0000f),
+          SkVector4(0.0000f, 1.0000f, 0.0000f, 1.0000f),
+          SkVector4(0.0000f, 0.0000f, 1.0000f, 1.0000f),
+      },
+  };
+
+  for (size_t i = 0; i < kNumColorSpaces; ++i) {
+    SkMatrix44 transfer;
+    color_spaces[i].GetTransferMatrix(&transfer);
+
+    SkMatrix44 range_adjust;
+    color_spaces[i].GetRangeAdjustMatrix(&range_adjust);
+
+    SkMatrix44 range_adjust_inv;
+    range_adjust.invert(&range_adjust_inv);
+
+    for (size_t j = 0; j < kNumTestRGBs; ++j) {
+      SkVector4 yuv = range_adjust_inv * transfer * test_rgbs[j];
+      EXPECT_LT(Diff(yuv, expected_yuvs[i][j]), kEpsilon);
+    }
+  }
+}
+
+}  // namespace
+}  // namespace gfx