1 files changed, 109 insertions, 0 deletions
diff --git a/src/com/android/tv/menu/ChannelsPosterPrefetcher.java b/src/com/android/tv/menu/ChannelsPosterPrefetcher.java
new file mode 100644
index 00000000..1dca6834
--- /dev/null
+++ b/src/com/android/tv/menu/ChannelsPosterPrefetcher.java
@@ -0,0 +1,109 @@
+/*
+ * 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.Message;
+import android.util.Log;
+
+import com.android.tv.R;
+import com.android.tv.data.Channel;
+import com.android.tv.data.Program;
+import com.android.tv.data.ProgramDataManager;
+
+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 final ProgramDataManager mProgramDataManager;
+    private final ChannelsRowAdapter mChannelsAdapter;
+    private final int mPosterArtWidth;
+    private final int mPosterArtHeight;
+    private final Context mContext;
+
+    private static final int MSG_PREFETCH_IMAGE = 1000;
+
+    private static final int ONDEMAND_POSTER_PREFETCH_DELAY_MILLIS = 500; // 500 milliseconds
+
+    private final Handler mHandler = new Handler() {
+        @Override
+        public void handleMessage(Message msg) {
+            switch (msg.what) {
+                case MSG_PREFETCH_IMAGE:
+                    doPrefetchImages();
+                    break;
+            }
+        }
+    };
+
+    /**
+     * 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;
+    }
+
+    /**
+     * Start prefetching of program poster art of recommendation.
+     */
+    public void prefetch() {
+        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);
+    }
+
+    private void doPrefetchImages() {
+        if (DEBUG) {
+            Log.d(TAG, "doPrefetchImages()");
+        }
+
+        List<Channel> channelList = mChannelsAdapter.getItemList();
+        if (channelList != null) {
+            for (Channel channel : channelList) {
+                if (!Channel.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);
+                }
+            }
+        }
+    }
+}