content: /*
   * Copyright (C) 2014 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 com.android.internal.view.animation;
  
  import android.animation.TimeInterpolator;
  import android.util.TimeUtils;
  import android.view.Choreographer;
  
  /**
   * Interpolator that builds a lookup table to use. This is a fallback for
   * building a native interpolator from a TimeInterpolator that is not marked
   * with {@link HasNativeInterpolator}
   *
   * This implements TimeInterpolator to allow for easier interop with Animators
   */
  @HasNativeInterpolator
  public class FallbackLUTInterpolator implements NativeInterpolatorFactory, TimeInterpolator {
  
      // If the duration of an animation is more than 300 frames, we cap the sample size to 300.
      private static final int MAX_SAMPLE_POINTS = 300;
      private TimeInterpolator mSourceInterpolator;
      private final float mLut[];
  
      /**
       * Used to cache the float[] LUT for use across multiple native
       * interpolator creation
       */
      public FallbackLUTInterpolator(TimeInterpolator interpolator, long duration) {
          mSourceInterpolator = interpolator;
          mLut = createLUT(interpolator, duration);
      }
  
      private static float[] createLUT(TimeInterpolator interpolator, long duration) {
          long frameIntervalNanos = Choreographer.getInstance().getFrameIntervalNanos();
          int animIntervalMs = (int) (frameIntervalNanos / TimeUtils.NANOS_PER_MS);
          // We need 2 frame values as the minimal.
          int numAnimFrames = Math.max(2, (int) Math.ceil(((double) duration) / animIntervalMs));
          numAnimFrames = Math.min(numAnimFrames, MAX_SAMPLE_POINTS);
          float values[] = new float[numAnimFrames];
          float lastFrame = numAnimFrames - 1;
          for (int i = 0; i < numAnimFrames; i++) {
              float inValue = i / lastFrame;
              values[i] = interpolator.getInterpolation(inValue);
          }
          return values;
      }
  
      @Override
      public long createNativeInterpolator() {
          return NativeInterpolatorFactoryHelper.createLutInterpolator(mLut);
      }
  
      /**
       * Used to create a one-shot float[] LUT & native interpolator
       */
      public static long createNativeInterpolator(TimeInterpolator interpolator, long duration) {
          float[] lut = createLUT(interpolator, duration);
          return NativeInterpolatorFactoryHelper.createLutInterpolator(lut);
      }
  
      @Override
      public float getInterpolation(float input) {
          return mSourceInterpolator.getInterpolation(input);
      }
  }
  