Scroll offset animation curve retargeting.

ui/gfx/geometry/cubic_bezier_unittest.cc

 // Copyright 2014 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 "ui/gfx/geometry/cubic_bezier.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace gfx {
@@ skipping 118 matching lines @@
   EXPECT_EQ(0, min);
   EXPECT_EQ(1, max);
 
   // Derivative has two roots > 1.
   function.reset(new CubicBezier(0.25, 0.367, 0.75, 0.7));
   function->Range(&min, &max);
   EXPECT_EQ(0.f, min);
   EXPECT_EQ(1.f, max);
 }
 
+TEST(CubicBezierTest, Slope) {
+  CubicBezier function(0.25, 0.0, 0.75, 1.0);
+
+  double epsilon = 0.00015;
+
+  EXPECT_NEAR(function.Slope(0), 0, epsilon);
+  EXPECT_NEAR(function.Slope(0.05), 0.42170, epsilon);
+  EXPECT_NEAR(function.Slope(0.1), 0.69778, epsilon);
+  EXPECT_NEAR(function.Slope(0.15), 0.89121, epsilon);
+  EXPECT_NEAR(function.Slope(0.2), 1.03184, epsilon);
+  EXPECT_NEAR(function.Slope(0.25), 1.13576, epsilon);
+  EXPECT_NEAR(function.Slope(0.3), 1.21239, epsilon);
+  EXPECT_NEAR(function.Slope(0.35), 1.26751, epsilon);
+  EXPECT_NEAR(function.Slope(0.4), 1.30474, epsilon);
+  EXPECT_NEAR(function.Slope(0.45), 1.32628, epsilon);
+  EXPECT_NEAR(function.Slope(0.5), 1.33333, epsilon);
+  EXPECT_NEAR(function.Slope(0.55), 1.32628, epsilon);
+  EXPECT_NEAR(function.Slope(0.6), 1.30474, epsilon);
+  EXPECT_NEAR(function.Slope(0.65), 1.26751, epsilon);
+  EXPECT_NEAR(function.Slope(0.7), 1.21239, epsilon);
+  EXPECT_NEAR(function.Slope(0.75), 1.13576, epsilon);
+  EXPECT_NEAR(function.Slope(0.8), 1.03184, epsilon);
+  EXPECT_NEAR(function.Slope(0.85), 0.89121, epsilon);
+  EXPECT_NEAR(function.Slope(0.9), 0.69778, epsilon);
+  EXPECT_NEAR(function.Slope(0.95), 0.42170, epsilon);
+  EXPECT_NEAR(function.Slope(1), 0, epsilon);
+}
+
 }  // namespace
 }  // namespace gfx