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.camera.async; 18 19 import javax.annotation.Nonnull; 20 21 /** 22 * Wraps an {@link com.android.camera.async.Updatable} by filtering out 23 * duplicate updates. 24 */ 25 public class FilteredUpdatable<T> implements Updatable<T> { 26 private final Updatable<T> mUpdatable; 27 private final Object mLock; 28 private boolean mValueSet; 29 private T mLatestValue; 30 31 public FilteredUpdatable(Updatable<T> updatable) { 32 mUpdatable = updatable; 33 mLock = new Object(); 34 mValueSet = false; 35 mLatestValue = null; 36 } 37 38 @Override 39 public void update(@Nonnull T t) { 40 synchronized (mLock) { 41 if (!mValueSet) { 42 setNewValue(t); 43 } else { 44 if (t == null && mLatestValue != null) { 45 setNewValue(t); 46 } else if (t != null) { 47 if (!t.equals(mLatestValue)) { 48 setNewValue(t); 49 } 50 } 51 } 52 } 53 } 54 55 private void setNewValue(T value) { 56 synchronized (mLock) { 57 mUpdatable.update(value); 58 mLatestValue = value; 59 mValueSet = true; 60 } 61 } 62 } 63
