Define accelerated steps time function.

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 409 matching lines @@
 
   EXPECT_FLOAT_EQ(0.f, curve->GetValue(0.f));
   EXPECT_LT(0.f, curve->GetValue(0.25f));
   EXPECT_GT(0.25f, curve->GetValue(0.25f));
   EXPECT_NEAR(curve->GetValue(0.5f), 0.5f, 0.00015f);
   EXPECT_LT(0.75f, curve->GetValue(0.75f));
   EXPECT_GT(1.f, curve->GetValue(0.75f));
   EXPECT_FLOAT_EQ(1.f, curve->GetValue(1.f));
 }
 
+// Tests that a steps timing function works as expected.
+TEST(KeyframedAnimationCurveTest, StepsTimingFunction) {
+  scoped_ptr<KeyframedFloatAnimationCurve> curve(
+      KeyframedFloatAnimationCurve::Create());
+  curve->AddKeyframe(FloatKeyframe::Create(
+      0.0,
+      0.f,
+      StepsTimingFunction::Create(36, false)
+          .PassAs<TimingFunction>()));
+  curve->AddKeyframe(
+      FloatKeyframe::Create(1.0, 1.f, scoped_ptr<TimingFunction>()));
+
+  EXPECT_FLOAT_EQ(0.f, curve->GetValue(0.f));
+  EXPECT_FLOAT_EQ(0.25f, curve->GetValue(0.25));

[ajuma, 2014/02/24 21:11:16]

0.25f

+  EXPECT_FLOAT_EQ(0.5f, curve->GetValue(0.5f));
+  EXPECT_FLOAT_EQ(0.75f, curve->GetValue(0.75));

[ajuma, 2014/02/24 21:11:16]

0.75f

+  EXPECT_FLOAT_EQ(1.f, curve->GetValue(1.f));

[ajuma, 2014/02/24 21:11:16]

It'd be good to also test values that don't land exactly on a step, e.g. 0.74f.

+}
+
 // Tests that animated bounds are computed as expected.
 TEST(KeyframedAnimationCurveTest, AnimatedBounds) {
   scoped_ptr<KeyframedTransformAnimationCurve> curve(
       KeyframedTransformAnimationCurve::Create());
 
   TransformOperations operations1;
   curve->AddKeyframe(TransformKeyframe::Create(
       0.0, operations1, scoped_ptr<TimingFunction>()));
   operations1.AppendTranslate(2.0, 3.0, -1.0);
   curve->AddKeyframe(TransformKeyframe::Create(
       0.5, operations1, scoped_ptr<TimingFunction>()));
   TransformOperations operations2;
   operations2.AppendTranslate(4.0, 1.0, 2.0);
   curve->AddKeyframe(TransformKeyframe::Create(
       1.0, operations2, EaseTimingFunction::Create()));
 
   gfx::BoxF box(2.f, 3.f, 4.f, 1.f, 3.f, 2.f);
   gfx::BoxF bounds;
 
   EXPECT_TRUE(curve->AnimatedBoundsForBox(box, &bounds));
   EXPECT_EQ(gfx::BoxF(2.f, 3.f, 3.f, 5.f, 6.f, 5.f).ToString(),
             bounds.ToString());
 }
 
 }  // namespace
 }  // namespace cc