Fix step timing outside range [0,1]

cc/animation/keyframed_animation_curve_unittest.cc

 // Copyright 2012 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 "cc/animation/keyframed_animation_curve.h"
 
 #include "cc/animation/transform_operations.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/animation/tween.h"
@@ skipping 800 matching lines @@
               0.002f);  // c(.46)=.38, k(.38)=.33
 
   EXPECT_NEAR(0.67f, curve->GetValue(base::TimeDelta::FromSecondsD(0.54f)),
               0.002f);  // c(.54)=.62, k(.62)=.67
   EXPECT_NEAR(1.02f, curve->GetValue(base::TimeDelta::FromSecondsD(0.75f)),
               0.002f);  // c(.75)=1.04 1+.04*0.5=1.02
 }
 
 // Tests that a step timing function works as expected for inputs outside of
 // range [0,1]
-TEST(KeyframedAnimationCurveTest, StepsTimingInputsOutsideZeroOneRange) {
+TEST(KeyframedAnimationCurveTest, StepsTimingStartInputsOutsideZeroOneRange) {
   std::unique_ptr<KeyframedFloatAnimationCurve> curve(
       KeyframedFloatAnimationCurve::Create());
   curve->AddKeyframe(
       FloatKeyframe::Create(base::TimeDelta(), 0.f,
                             StepsTimingFunction::Create(
-                                4, StepsTimingFunction::StepPosition::MIDDLE)));
+                                4, StepsTimingFunction::StepPosition::START)));
   curve->AddKeyframe(
       FloatKeyframe::Create(base::TimeDelta::FromSecondsD(1.0), 2.f, nullptr));
   // Curve timing function producing timing outputs outside of range [0,1].
   curve->SetTimingFunction(
       CubicBezierTimingFunction::Create(0.5f, -0.5f, 0.5f, 1.5f));
 
   EXPECT_FLOAT_EQ(0.f, curve->GetValue(base::TimeDelta::FromSecondsD(0.25f)));
+  EXPECT_FLOAT_EQ(2.5f, curve->GetValue(base::TimeDelta::FromSecondsD(0.75f)));
+}
+
+TEST(KeyframedAnimationCurveTest, StepsTimingEndInputsOutsideZeroOneRange) {
+  std::unique_ptr<KeyframedFloatAnimationCurve> curve(
+      KeyframedFloatAnimationCurve::Create());
+  curve->AddKeyframe(FloatKeyframe::Create(
+      base::TimeDelta(), 0.f,
+      StepsTimingFunction::Create(4, StepsTimingFunction::StepPosition::END)));
+  curve->AddKeyframe(
+      FloatKeyframe::Create(base::TimeDelta::FromSecondsD(1.0), 2.f, nullptr));
+  // Curve timing function producing timing outputs outside of range [0,1].
+  curve->SetTimingFunction(
+      CubicBezierTimingFunction::Create(0.5f, -0.5f, 0.5f, 1.5f));
+
+  EXPECT_FLOAT_EQ(-0.5f, curve->GetValue(base::TimeDelta::FromSecondsD(0.25f)));
   EXPECT_FLOAT_EQ(2.f, curve->GetValue(base::TimeDelta::FromSecondsD(0.75f)));
 }
 
 // Tests that an animation with a curve timing function and multiple keyframes
 // works as expected.
 TEST(KeyframedAnimationCurveTest, CurveTimingMultipleKeyframes) {
   std::unique_ptr<KeyframedFloatAnimationCurve> curve(
       KeyframedFloatAnimationCurve::Create());
   curve->AddKeyframe(FloatKeyframe::Create(base::TimeDelta(), 0.f, nullptr));
   curve->AddKeyframe(
@@ skipping 79 matching lines @@
               curve->GetValue(base::TimeDelta::FromSecondsD(scale * 3.5f)),
               0.01f);
   EXPECT_FLOAT_EQ(9.f,
                   curve->GetValue(base::TimeDelta::FromSecondsD(scale * 4.f)));
   EXPECT_FLOAT_EQ(9.f,
                   curve->GetValue(base::TimeDelta::FromSecondsD(scale * 5.f)));
 }
 
 }  // namespace
 }  // namespace cc