Android Open Source - favouritetv Async Image Loader

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Back to project page favouritetv.
License

The source code is released under:
Copyright (c) 2011 Andr? Prata<andreprata@ua.pt> Eriksson Monteiro<eriksson.monteiro@ua.pt> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associat...
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Java Source Code

package pt.ua.code.favouritetv.gui;
//  w w  w  .j ava  2 s  .  co m
import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map.Entry;

import pt.ua.code.favouritetv.R;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

public class AsyncImageLoader {

  private static HashMap<String, SoftReference<Bitmap>> imageCache;
  private static final AsyncImageLoader instance = new AsyncImageLoader();
  private static final Thread controler[] = new Thread[8];
  private static int threadCount = 0;
  private static final List<String> receivingUrlsImage = new LinkedList<String>();

  private AsyncImageLoader() {
    imageCache = new HashMap<String, SoftReference<Bitmap>>();
  }

  public static final AsyncImageLoader getInstance() {
    return instance;
  }

  public boolean isReceivingImage(String imageUrl) {
    return receivingUrlsImage.contains(imageUrl);
  }

  public static Bitmap getImageInCache(String imageUrl) {
    if (imageCache.containsKey(imageUrl)) {
      SoftReference<Bitmap> softReference = imageCache.get(imageUrl);
      Bitmap drawable = softReference.get();
      if (drawable != null) {
        return drawable;
      }
    }
    return null;
  }

  public Bitmap loadDrawableFromResources(final Context context, final String imageUrl, final String res,
      final ImageCallback imageCallback) {

    Bitmap tmp = null;
    if ((tmp = getImageInCache(imageUrl)) != null) {
      return tmp;
    }

    receivingUrlsImage.add(imageUrl);

    final Handler handler = new Handler() {
      @Override
      public void handleMessage(Message message) {
        imageCallback.imageLoaded(((Bitmap) message.obj), imageUrl);
        receivingUrlsImage.remove(imageUrl);
      }
    };

    if (controler[threadCount] != null) {
      try {
        if (controler[threadCount] != null)
          controler[threadCount].join();
        if (controler[threadCount] != null)
          controler[threadCount].destroy();
      } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      controler[threadCount] = null;
    }

    controler[threadCount] = new Thread() {
      private String localUrl;

      @Override
      public void run() {
        localUrl = imageUrl;
        Bitmap drawable = loadImageFromResources(context, res);
        imageCache.put(imageUrl, new SoftReference<Bitmap>(drawable));
        Message message = handler.obtainMessage(0, drawable);
        handler.sendMessage(message);
      }

      @Override
      public void destroy() {
        // TODO Auto-generated method stub
        receivingUrlsImage.remove(localUrl);
      }

    };

    controler[threadCount].setPriority(Thread.MIN_PRIORITY);
    controler[threadCount].start();
    threadCount = (threadCount + 1) % controler.length;
    return null;
  }

  @SuppressWarnings("unchecked")
  private static void dropOneCacheEntry() {
    try {
      Iterator<Entry<String, SoftReference<Bitmap>>> it = imageCache.entrySet().iterator();
      Object tmp;
      String key = null;

      if (it.hasNext()) {

        tmp = it.next();
        if (tmp != null) {
          key = ((Entry<String, SoftReference<Bitmap>>) tmp).getKey();

          tmp = ((Entry<String, SoftReference<Bitmap>>) tmp).getValue();

        }
        if (tmp != null)
          tmp = ((Reference<Bitmap>) tmp).get();

        if (tmp != null)
          if (tmp instanceof Bitmap) {
            // ((Bitmap) tmp).recycle();
            tmp = null;
            Log.i("Recycling", "One bitmap Recycled");
          }

        imageCache.remove(key);
      }

    } catch (ConcurrentModificationException e) {

    }
  }

  public static Bitmap loadImageFromResources(Context context, String resource) {

    Bitmap ret = null;
    Options opts = new Options();
    opts.inPurgeable = true;
    opts.inPreferredConfig = Config.ARGB_8888;
    Resources res = context.getResources();
    try {

      ret = BitmapFactory.decodeResource(res,
          res.getIdentifier("channel_" + formatResouceName(resource), "drawable", context.getPackageName()),
          opts);
      if (ret == null) {
        ret = BitmapFactory.decodeResource(res, R.drawable.channel_demo, opts);
      }

    } catch (OutOfMemoryError error) {
      for (int i = 0; i < 6; i++) {
        Log.i("Recycling", "One bitmap Recycled because of memory");
        dropOneCacheEntry();
      }
      System.gc();
      try {
        Thread.sleep(200);
      } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }

    } catch (Resources.NotFoundException e) {
      ret = BitmapFactory.decodeResource(res, R.drawable.channel_demo, opts);
    }
    return ret;
  }

  private static String formatResouceName(String sigla) {
    StringBuffer result = new StringBuffer();
    for (int i = 0; i < sigla.length(); i++) {
      char c = sigla.charAt(i);
      if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_' || c == '.') {
        result.append(c);
      }
    }
    return result.toString().toLowerCase();
  }

  public final void stopLoadingImages() {
    for (int i = 0; i < threadCount; i++) {
      if (controler[i] != null) {
        // try {
        controler[i].interrupt();
        // controler[i].join();
        // } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        // e.printStackTrace();
        // }
        controler[i] = null;
      }

    }
    System.gc();
  }

  public interface ImageCallback {
    public void imageLoaded(Bitmap imageDrawable, String imageTag);
  }
}
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