Jeff Brown | 9630704 | 2012-07-27 15:51:34 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2012 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.server.power; |
| 18 | |
| 19 | import android.animation.ValueAnimator; |
| 20 | import android.util.IntProperty; |
| 21 | import android.view.Choreographer; |
| 22 | |
| 23 | /** |
| 24 | * A custom animator that progressively updates a property value at |
| 25 | * a given variable rate until it reaches a particular target value. |
| 26 | */ |
| 27 | final class RampAnimator<T> { |
| 28 | private final T mObject; |
| 29 | private final IntProperty<T> mProperty; |
| 30 | private final Choreographer mChoreographer; |
| 31 | |
| 32 | private int mCurrentValue; |
| 33 | private int mTargetValue; |
| 34 | private int mRate; |
| 35 | |
| 36 | private boolean mAnimating; |
| 37 | private float mAnimatedValue; // higher precision copy of mCurrentValue |
| 38 | private long mLastFrameTimeNanos; |
| 39 | |
| 40 | private boolean mFirstTime = true; |
| 41 | |
| 42 | public RampAnimator(T object, IntProperty<T> property) { |
| 43 | mObject = object; |
| 44 | mProperty = property; |
| 45 | mChoreographer = Choreographer.getInstance(); |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * Starts animating towards the specified value. |
| 50 | * |
| 51 | * If this is the first time the property is being set, the value jumps |
| 52 | * directly to the target. |
| 53 | * |
| 54 | * @param target The target value. |
| 55 | * @param rate The convergence rate, in units per second. |
| 56 | * @return True if the target differs from the previous target. |
| 57 | */ |
| 58 | public boolean animateTo(int target, int rate) { |
| 59 | // Immediately jump to the target the first time. |
| 60 | if (mFirstTime) { |
| 61 | mFirstTime = false; |
| 62 | mProperty.setValue(mObject, target); |
| 63 | mCurrentValue = target; |
| 64 | return true; |
| 65 | } |
| 66 | |
| 67 | // Adjust the rate based on the closest target. |
| 68 | // If a faster rate is specified, then use the new rate so that we converge |
| 69 | // more rapidly based on the new request. |
| 70 | // If a slower rate is specified, then use the new rate only if the current |
| 71 | // value is somewhere in between the new and the old target meaning that |
| 72 | // we will be ramping in a different direction to get there. |
| 73 | // Otherwise, continue at the previous rate. |
| 74 | if (!mAnimating |
| 75 | || rate > mRate |
| 76 | || (target <= mCurrentValue && mCurrentValue <= mTargetValue) |
| 77 | || (mTargetValue <= mCurrentValue && mCurrentValue <= target)) { |
| 78 | mRate = rate; |
| 79 | } |
| 80 | |
| 81 | final boolean changed = (mTargetValue != target); |
| 82 | mTargetValue = target; |
| 83 | |
| 84 | // Start animating. |
| 85 | if (!mAnimating && target != mCurrentValue) { |
| 86 | mAnimating = true; |
| 87 | mAnimatedValue = mCurrentValue; |
| 88 | mLastFrameTimeNanos = System.nanoTime(); |
| 89 | postCallback(); |
| 90 | } |
| 91 | |
| 92 | return changed; |
| 93 | } |
| 94 | |
| 95 | private void postCallback() { |
| 96 | mChoreographer.postCallback(Choreographer.CALLBACK_ANIMATION, mCallback, null); |
| 97 | } |
| 98 | |
| 99 | private final Runnable mCallback = new Runnable() { |
| 100 | @Override // Choreographer callback |
| 101 | public void run() { |
| 102 | final long frameTimeNanos = mChoreographer.getFrameTimeNanos(); |
| 103 | final float timeDelta = (frameTimeNanos - mLastFrameTimeNanos) |
| 104 | * 0.000000001f; |
Jeff Brown | 9630704 | 2012-07-27 15:51:34 -0700 | [diff] [blame] | 105 | mLastFrameTimeNanos = frameTimeNanos; |
| 106 | |
| 107 | // Advance the animated value towards the target at the specified rate |
| 108 | // and clamp to the target. This gives us the new current value but |
| 109 | // we keep the animated value around to allow for fractional increments |
| 110 | // towards the target. |
Craig Mautner | 9dd9e0c | 2012-11-15 14:25:14 -0800 | [diff] [blame] | 111 | final float scale = ValueAnimator.getDurationScale(); |
| 112 | if (scale == 0) { |
| 113 | // Animation off. |
| 114 | mAnimatedValue = mTargetValue; |
Jeff Brown | 9630704 | 2012-07-27 15:51:34 -0700 | [diff] [blame] | 115 | } else { |
Craig Mautner | 9dd9e0c | 2012-11-15 14:25:14 -0800 | [diff] [blame] | 116 | final float amount = timeDelta * mRate / scale; |
| 117 | if (mTargetValue > mCurrentValue) { |
| 118 | mAnimatedValue = Math.min(mAnimatedValue + amount, mTargetValue); |
| 119 | } else { |
| 120 | mAnimatedValue = Math.max(mAnimatedValue - amount, mTargetValue); |
| 121 | } |
Jeff Brown | 9630704 | 2012-07-27 15:51:34 -0700 | [diff] [blame] | 122 | } |
Craig Mautner | 9dd9e0c | 2012-11-15 14:25:14 -0800 | [diff] [blame] | 123 | final int oldCurrentValue = mCurrentValue; |
| 124 | mCurrentValue = Math.round(mAnimatedValue); |
Jeff Brown | 9630704 | 2012-07-27 15:51:34 -0700 | [diff] [blame] | 125 | |
| 126 | if (oldCurrentValue != mCurrentValue) { |
| 127 | mProperty.setValue(mObject, mCurrentValue); |
| 128 | } |
| 129 | |
| 130 | if (mTargetValue != mCurrentValue) { |
| 131 | postCallback(); |
| 132 | } else { |
| 133 | mAnimating = false; |
| 134 | } |
| 135 | } |
| 136 | }; |
| 137 | } |