1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.internal.view.animation; 18 19 import android.animation.TimeInterpolator; 20 import android.util.TimeUtils; 21 import android.view.Choreographer; 22 23 /** 24 * Interpolator that builds a lookup table to use. This is a fallback for 25 * building a native interpolator from a TimeInterpolator that is not marked 26 * with {@link HasNativeInterpolator} 27 * 28 * This implements TimeInterpolator to allow for easier interop with Animators 29 */ 30 @HasNativeInterpolator 31 public class FallbackLUTInterpolator implements NativeInterpolatorFactory, TimeInterpolator { 32 33 // If the duration of an animation is more than 300 frames, we cap the sample size to 300. 34 private static final int MAX_SAMPLE_POINTS = 300; 35 private TimeInterpolator mSourceInterpolator; 36 private final float mLut[]; 37 38 /** 39 * Used to cache the float[] LUT for use across multiple native 40 * interpolator creation 41 */ 42 public FallbackLUTInterpolator(TimeInterpolator interpolator, long duration) { 43 mSourceInterpolator = interpolator; 44 mLut = createLUT(interpolator, duration); 45 } 46 47 private static float[] createLUT(TimeInterpolator interpolator, long duration) { 48 long frameIntervalNanos = Choreographer.getInstance().getFrameIntervalNanos(); 49 int animIntervalMs = (int) (frameIntervalNanos / TimeUtils.NANOS_PER_MS); 50 // We need 2 frame values as the minimal. 51 int numAnimFrames = Math.max(2, (int) Math.ceil(((double) duration) / animIntervalMs)); 52 numAnimFrames = Math.min(numAnimFrames, MAX_SAMPLE_POINTS); 53 float values[] = new float[numAnimFrames]; 54 float lastFrame = numAnimFrames - 1; 55 for (int i = 0; i < numAnimFrames; i++) { 56 float inValue = i / lastFrame; 57 values[i] = interpolator.getInterpolation(inValue); 58 } 59 return values; 60 } 61 62 @Override 63 public long createNativeInterpolator() { 64 return NativeInterpolatorFactoryHelper.createLutInterpolator(mLut); 65 } 66 67 /** 68 * Used to create a one-shot float[] LUT & native interpolator 69 */ 70 public static long createNativeInterpolator(TimeInterpolator interpolator, long duration) { 71 float[] lut = createLUT(interpolator, duration); 72 return NativeInterpolatorFactoryHelper.createLutInterpolator(lut); 73 } 74 75 @Override 76 public float getInterpolation(float input) { 77 return mSourceInterpolator.getInterpolation(input); 78 } 79 } 80
