| /* |
| * 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.v4.view.animation; |
| |
| import android.view.animation.Interpolator; |
| |
| /** |
| * An {@link Interpolator} that uses a lookup table to compute an interpolation based on a |
| * given input. |
| */ |
| abstract class LookupTableInterpolator implements Interpolator { |
| |
| private final float[] mValues; |
| private final float mStepSize; |
| |
| public LookupTableInterpolator(float[] values) { |
| mValues = values; |
| mStepSize = 1f / (mValues.length - 1); |
| } |
| |
| @Override |
| public float getInterpolation(float input) { |
| if (input >= 1.0f) { |
| return 1.0f; |
| } |
| if (input <= 0f) { |
| return 0f; |
| } |
| |
| // Calculate index - We use min with length - 2 to avoid IndexOutOfBoundsException when |
| // we lerp (linearly interpolate) in the return statement |
| int position = Math.min((int) (input * (mValues.length - 1)), mValues.length - 2); |
| |
| // Calculate values to account for small offsets as the lookup table has discrete values |
| float quantized = position * mStepSize; |
| float diff = input - quantized; |
| float weight = diff / mStepSize; |
| |
| // Linearly interpolate between the table values |
| return mValues[position] + weight * (mValues[position + 1] - mValues[position]); |
| } |
| |
| } |