Android Open Source - lightbox-android-webservices Bitmap Loader Task

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License

The source code is released under:
Apache License
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Java Source Code

/**
 * Copyright (c) 2012 Lightbox//from ww  w. j  a v  a  2  s  . c  o m
 *
 * 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.lightbox.android.bitmap;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;

import com.lightbox.android.bitmap.BitmapLoader.Volatility;
import com.lightbox.android.cache.BitmapCache;
import com.lightbox.android.tasks.BackgroundTaskWeak;
import com.lightbox.android.utils.debug.DebugLog;

/** 
 * BitmapLoaderTask 
 * @author Fabien Devos & Nilesh Patel
 */
/*package*/ class BitmapLoaderTask extends BackgroundTaskWeak<BitmapLoaderListener, Bitmap> {
  /** Used to tag logs */
  //@SuppressWarnings("unused")
  private static final String TAG = "BitmapLoaderTask";
  
  private static final int DEFAULT_CORE_POOL_SIZE = 6; //Maximum number of Threads running in parallel
    private static final int MAXIMUM_POOL_SIZE = Integer.MAX_VALUE; // Will be ignored as long as the queue is unbounded
    private static final int KEEP_ALIVE = 10000; //(in milliseconds)
    
    private static ExecutorService sSingleThreadExecutor;
  private static ExecutorService sBitmapExecutor;

  private BitmapSource mBitmapSource;
  private BitmapSource.Type mType;
  private Config mConfig;
  private Volatility mVolatility;
  
  //----------------------------------------------
  // Constructors
  
  /**
   * Constructor.
   * @param listener
   */
  public BitmapLoaderTask(BitmapSource bitmapSource, BitmapSource.Type type, Config config, Volatility volatility, BitmapLoaderListener listener) {
    super(listener, getBitmapExecutor(bitmapSource, type));
    mBitmapSource = bitmapSource;
    mType = type;
    mConfig = config;
    mVolatility = volatility;
  }
  
  private static ExecutorService getBitmapExecutor(BitmapSource bitmapSource, BitmapSource.Type type) {
    // If the file exist on disk, use a single thread executor 
    if (BitmapCache.getInstance().existOnDisk(bitmapSource.getAbsoluteFileName(type))) {
      if (sSingleThreadExecutor == null) {
        sSingleThreadExecutor = Executors.newSingleThreadExecutor(
            new BitmapLoaderThreadFactory("single thread"));
      }
      return sSingleThreadExecutor;
    } else {
      // Else use a thread pool executor
      if (sBitmapExecutor == null) {
        sBitmapExecutor = new ThreadPoolExecutor(
            DEFAULT_CORE_POOL_SIZE,
            MAXIMUM_POOL_SIZE,
            KEEP_ALIVE, TimeUnit.MILLISECONDS,
            new LinkedBlockingQueue<Runnable>(), 
            new BitmapLoaderThreadFactory("multiple threads"));
      }
      return sBitmapExecutor;
    }
  }
  
  //----------------------------------------------
  // BackgroundTask implementation

  @Override
  protected Bitmap doWorkInBackground() throws Exception {
    DebugLog.d(TAG, "Start loading bitmap: "+mBitmapSource.getUri(mType));
    return BitmapLoader.loadFromDiskOrNetwork(mBitmapSource, mType, mConfig, mVolatility);
  }

  @Override
  protected void onCompleted(Bitmap bitmap) {    
    BitmapLoaderListener listener = getRef();
    if (listener != null) {
      if (bitmap == null) {
        listener.onFailure(new NullPointerException("bitmap is null"));
      } else {
        listener.onLoaded(bitmap, mType, false);
      }
    }
  }

  @Override
  protected void onFailed(Exception exception) {
    BitmapLoaderListener listener = getRef();
    if (listener != null) {
      listener.onFailure(exception);
    }
  }

  /************************************************
   * BitmapLoaderThreadFactory 
   */
  private static class BitmapLoaderThreadFactory implements ThreadFactory {
    private String mType;
    /** Constructor.*/
    public BitmapLoaderThreadFactory(String type) {
      mType = type;
    }
    // -------------------------
    @Override
    public Thread newThread(Runnable r) {
      Thread thread = new Thread(r);
      thread.setName(TAG + " thread | " + mType);
      thread.setPriority(Thread.NORM_PRIORITY);
      return thread;
    }
  }

}
Java Source Code List
