| /* |
| * Copyright (C) 2017 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.wear.widget; |
| |
| import android.animation.TimeInterpolator; |
| import android.support.annotation.RestrictTo; |
| import android.support.annotation.RestrictTo.Scope; |
| |
| /** |
| * Interpolator that uses a Bezier derived S shaped curve. |
| * |
| * @hide |
| */ |
| @RestrictTo(Scope.LIBRARY) |
| class BezierSCurveInterpolator implements TimeInterpolator { |
| |
| /** |
| * An instance of {@link BezierSCurveInterpolator}. |
| */ |
| public static final BezierSCurveInterpolator INSTANCE = new BezierSCurveInterpolator(); |
| /** |
| * 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) |
| * |
| * <p>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); |
| |
| /** |
| * To avoid users of this class creating multiple copies needlessly, the constructor is |
| * private. |
| */ |
| private BezierSCurveInterpolator() { |
| } |
| |
| @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]); |
| } |
| } |