1 files changed, 84 insertions, 0 deletions
diff --git a/src/android/support/wearable/view/Gusterpolator.java b/src/android/support/wearable/view/Gusterpolator.java
new file mode 100644
index 00000000..dc85bcb5
--- /dev/null
+++ b/src/android/support/wearable/view/Gusterpolator.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package android.support.wearable.view;
+
+import android.animation.TimeInterpolator;
+import android.annotation.TargetApi;
+import android.os.Build;
+
+/**
+ * Interpolator that uses a Bezier derived S shaped curve.
+ * @hide
+ */
+@TargetApi(Build.VERSION_CODES.KITKAT_WATCH)
+class Gusterpolator implements TimeInterpolator {
+
+    /** An instance of {@link android.support.wearable.view.Gusterpolator}. */
+    public static final Gusterpolator INSTANCE = new Gusterpolator();
+
+    /**
+     * To avoid users of this class creating multiple copies needlessly, the constructor is
+     * private.
+     */
+    private Gusterpolator() {}
+
+    /**
+     * Lookup table values.
+     * Generated using a Bezier curve from (0,0) to (1,1) with control points:
+     * P0 (0,0)
+     * P1 (0.4, 0)
+     * P2 (0.2, 1.0)
+     * P3 (1.0, 1.0)
+     *
+     * Values sampled with x at regular intervals between 0 and 1.
+     */
+    private static final float[] VALUES = new float[] {
+        0.0f, 0.0002f, 0.0009f, 0.0019f, 0.0036f, 0.0059f, 0.0086f, 0.0119f, 0.0157f, 0.0209f,
+        0.0257f, 0.0321f, 0.0392f, 0.0469f, 0.0566f, 0.0656f, 0.0768f, 0.0887f, 0.1033f, 0.1186f,
+        0.1349f, 0.1519f, 0.1696f, 0.1928f, 0.2121f, 0.237f, 0.2627f, 0.2892f, 0.3109f, 0.3386f,
+        0.3667f, 0.3952f, 0.4241f, 0.4474f, 0.4766f, 0.5f, 0.5234f, 0.5468f, 0.5701f, 0.5933f,
+        0.6134f, 0.6333f, 0.6531f, 0.6698f, 0.6891f, 0.7054f, 0.7214f, 0.7346f, 0.7502f, 0.763f,
+        0.7756f, 0.7879f, 0.8f, 0.8107f, 0.8212f, 0.8326f, 0.8415f, 0.8503f, 0.8588f, 0.8672f,
+        0.8754f, 0.8833f, 0.8911f, 0.8977f, 0.9041f, 0.9113f, 0.9165f, 0.9232f, 0.9281f, 0.9328f,
+        0.9382f, 0.9434f, 0.9476f, 0.9518f, 0.9557f, 0.9596f, 0.9632f, 0.9662f, 0.9695f, 0.9722f,
+        0.9753f, 0.9777f, 0.9805f, 0.9826f, 0.9847f, 0.9866f, 0.9884f, 0.9901f, 0.9917f, 0.9931f,
+        0.9944f, 0.9955f, 0.9964f, 0.9973f, 0.9981f, 0.9986f, 0.9992f, 0.9995f, 0.9998f, 1.0f, 1.0f
+    };
+
+    private static final float STEP_SIZE = 1.0f / (VALUES.length - 1);
+
+    @Override
+    public float getInterpolation(float input) {
+        if (input >= 1.0f) {
+            return 1.0f;
+        }
+
+        if (input <= 0f) {
+            return 0f;
+        }
+
+        int position = Math.min(
+                (int)(input * (VALUES.length - 1)),
+                VALUES.length - 2);
+
+        float quantized = position * STEP_SIZE;
+        float difference = input - quantized;
+        float weight = difference / STEP_SIZE;
+
+        return VALUES[position] + weight * (VALUES[position + 1] - VALUES[position]);
+    }
+}