1 /* 2 * Copyright (C) 2015 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.tv.menu; 18 19 import android.content.Context; 20 import android.os.Handler; 21 import android.os.Looper; 22 import android.os.Message; 23 import android.support.annotation.MainThread; 24 import android.support.annotation.NonNull; 25 import android.util.Log; 26 import com.android.tv.R; 27 import com.android.tv.common.SoftPreconditions; 28 import com.android.tv.common.WeakHandler; 29 import com.android.tv.data.ChannelImpl; 30 import com.android.tv.data.Program; 31 import com.android.tv.data.ProgramDataManager; 32 import com.android.tv.data.api.Channel; 33 import java.util.List; 34 35 /** A poster image prefetcher to show the program poster art in the Channels row faster. */ 36 public class ChannelsPosterPrefetcher { 37 private static final String TAG = "PosterPrefetcher"; 38 private static final boolean DEBUG = false; 39 private static final int MSG_PREFETCH_IMAGE = 1000; 40 private static final int ONDEMAND_POSTER_PREFETCH_DELAY_MILLIS = 500; // 500 milliseconds 41 42 private final ProgramDataManager mProgramDataManager; 43 private final ChannelsRowAdapter mChannelsAdapter; 44 private final int mPosterArtWidth; 45 private final int mPosterArtHeight; 46 private final Context mContext; 47 private final Handler mHandler = new PrefetchHandler(this); 48 49 private boolean isCanceled; 50 51 /** Create {@link ChannelsPosterPrefetcher} object with given parameters. */ ChannelsPosterPrefetcher( Context context, ProgramDataManager programDataManager, ChannelsRowAdapter adapter)52 public ChannelsPosterPrefetcher( 53 Context context, ProgramDataManager programDataManager, ChannelsRowAdapter adapter) { 54 mProgramDataManager = programDataManager; 55 mChannelsAdapter = adapter; 56 mPosterArtWidth = 57 context.getResources().getDimensionPixelSize(R.dimen.card_image_layout_width); 58 mPosterArtHeight = 59 context.getResources().getDimensionPixelSize(R.dimen.card_image_layout_height); 60 mContext = context.getApplicationContext(); 61 } 62 63 /** Start prefetching of program poster art of recommendation. */ prefetch()64 public void prefetch() { 65 SoftPreconditions.checkState(!isCanceled, TAG, "Prefetch called after cancel was called."); 66 if (isCanceled) { 67 return; 68 } 69 if (DEBUG) Log.d(TAG, "startPrefetching()"); 70 /* 71 * When a user browse channels, this method could be called many times. We don't need to 72 * prefetch the intermediate channels. So ignore previous schedule. 73 */ 74 mHandler.removeMessages(MSG_PREFETCH_IMAGE); 75 mHandler.sendMessageDelayed( 76 mHandler.obtainMessage(MSG_PREFETCH_IMAGE), ONDEMAND_POSTER_PREFETCH_DELAY_MILLIS); 77 } 78 79 /** Cancels pending and current prefetch requests. */ cancel()80 public void cancel() { 81 isCanceled = true; 82 mHandler.removeCallbacksAndMessages(null); 83 } 84 85 @MainThread // ProgramDataManager.getCurrentProgram must be called from the main thread doPrefetchImages()86 private void doPrefetchImages() { 87 if (DEBUG) Log.d(TAG, "doPrefetchImages() started"); 88 89 // This executes on the main thread, but since the item list is expected to be about 5 items 90 // and ImageLoader spawns an async task so this is fast enough. 1 ms in local testing. 91 List<ChannelsRowItem> items = mChannelsAdapter.getItemList(); 92 if (items != null) { 93 for (ChannelsRowItem item : items) { 94 if (isCanceled) { 95 return; 96 } 97 Channel channel = item.getChannel(); 98 if (!ChannelImpl.isValid(channel)) { 99 continue; 100 } 101 channel.prefetchImage( 102 mContext, 103 Channel.LOAD_IMAGE_TYPE_CHANNEL_LOGO, 104 mPosterArtWidth, 105 mPosterArtHeight); 106 Program program = mProgramDataManager.getCurrentProgram(channel.getId()); 107 if (program != null) { 108 program.prefetchPosterArt(mContext, mPosterArtWidth, mPosterArtHeight); 109 } 110 } 111 } 112 if (DEBUG) { 113 Log.d( 114 TAG, 115 "doPrefetchImages() finished. ImageLoader may still have async tasks for " 116 + "channels " 117 + items); 118 } 119 } 120 121 private static class PrefetchHandler extends WeakHandler<ChannelsPosterPrefetcher> { PrefetchHandler(ChannelsPosterPrefetcher ref)122 public PrefetchHandler(ChannelsPosterPrefetcher ref) { 123 // doPrefetchImages must be called from the main thread. 124 super(Looper.getMainLooper(), ref); 125 } 126 127 @Override 128 @MainThread handleMessage(Message msg, @NonNull ChannelsPosterPrefetcher prefetcher)129 public void handleMessage(Message msg, @NonNull ChannelsPosterPrefetcher prefetcher) { 130 switch (msg.what) { 131 case MSG_PREFETCH_IMAGE: 132 prefetcher.doPrefetchImages(); 133 break; 134 } 135 } 136 } 137 } 138