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/*
* Copyright (C) 2015 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.tv.menu;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.annotation.MainThread;
import android.support.annotation.NonNull;
import android.util.Log;
import com.android.tv.R;
import com.android.tv.common.SoftPreconditions;
import com.android.tv.common.WeakHandler;
import com.android.tv.data.ChannelImpl;
import com.android.tv.data.Program;
import com.android.tv.data.ProgramDataManager;
import com.android.tv.data.api.Channel;
import java.util.List;
/** A poster image prefetcher to show the program poster art in the Channels row faster. */
public class ChannelsPosterPrefetcher {
private static final String TAG = "PosterPrefetcher";
private static final boolean DEBUG = false;
private static final int MSG_PREFETCH_IMAGE = 1000;
private static final int ONDEMAND_POSTER_PREFETCH_DELAY_MILLIS = 500; // 500 milliseconds
private final ProgramDataManager mProgramDataManager;
private final ChannelsRowAdapter mChannelsAdapter;
private final int mPosterArtWidth;
private final int mPosterArtHeight;
private final Context mContext;
private final Handler mHandler = new PrefetchHandler(this);
private boolean isCanceled;
/** Create {@link ChannelsPosterPrefetcher} object with given parameters. */
public ChannelsPosterPrefetcher(
Context context, ProgramDataManager programDataManager, ChannelsRowAdapter adapter) {
mProgramDataManager = programDataManager;
mChannelsAdapter = adapter;
mPosterArtWidth =
context.getResources().getDimensionPixelSize(R.dimen.card_image_layout_width);
mPosterArtHeight =
context.getResources().getDimensionPixelSize(R.dimen.card_image_layout_height);
mContext = context.getApplicationContext();
}
/** Start prefetching of program poster art of recommendation. */
public void prefetch() {
SoftPreconditions.checkState(!isCanceled, TAG, "Prefetch called after cancel was called.");
if (isCanceled) {
return;
}
if (DEBUG) Log.d(TAG, "startPrefetching()");
/*
* When a user browse channels, this method could be called many times. We don't need to
* prefetch the intermediate channels. So ignore previous schedule.
*/
mHandler.removeMessages(MSG_PREFETCH_IMAGE);
mHandler.sendMessageDelayed(
mHandler.obtainMessage(MSG_PREFETCH_IMAGE), ONDEMAND_POSTER_PREFETCH_DELAY_MILLIS);
}
/** Cancels pending and current prefetch requests. */
public void cancel() {
isCanceled = true;
mHandler.removeCallbacksAndMessages(null);
}
@MainThread // ProgramDataManager.getCurrentProgram must be called from the main thread
private void doPrefetchImages() {
if (DEBUG) Log.d(TAG, "doPrefetchImages() started");
// This executes on the main thread, but since the item list is expected to be about 5 items
// and ImageLoader spawns an async task so this is fast enough. 1 ms in local testing.
List<ChannelsRowItem> items = mChannelsAdapter.getItemList();
if (items != null) {
for (ChannelsRowItem item : items) {
if (isCanceled) {
return;
}
Channel channel = item.getChannel();
if (!ChannelImpl.isValid(channel)) {
continue;
}
channel.prefetchImage(
mContext,
Channel.LOAD_IMAGE_TYPE_CHANNEL_LOGO,
mPosterArtWidth,
mPosterArtHeight);
Program program = mProgramDataManager.getCurrentProgram(channel.getId());
if (program != null) {
program.prefetchPosterArt(mContext, mPosterArtWidth, mPosterArtHeight);
}
}
}
if (DEBUG) {
Log.d(
TAG,
"doPrefetchImages() finished. ImageLoader may still have async tasks for "
+ "channels "
+ items);
}
}
private static class PrefetchHandler extends WeakHandler<ChannelsPosterPrefetcher> {
public PrefetchHandler(ChannelsPosterPrefetcher ref) {
// doPrefetchImages must be called from the main thread.
super(Looper.getMainLooper(), ref);
}
@Override
@MainThread
public void handleMessage(Message msg, @NonNull ChannelsPosterPrefetcher prefetcher) {
switch (msg.what) {
case MSG_PREFETCH_IMAGE:
prefetcher.doPrefetchImages();
break;
}
}
}
}
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