Android Open Source - FileManager Image Preview

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License

The source code is released under:

GNU General Public License

Java Source Code

package com.ankur.coreutils;
/*from ww w.j  av a 2  s.c o m*/
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import java.util.Collections;

import java.util.Map;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;

import android.util.Log;
import android.widget.ImageView;

public enum ImagePreview {
  INSTANCE;

  private final ConcurrentMap<String, Bitmap> cache;
  private final ExecutorService pool;
  private Map<ImageView, String> imageViews = Collections
      .synchronizedMap(new ConcurrentHashMap<ImageView, String>());
  private Bitmap placeholder;

  ImagePreview() {
    cache = new ConcurrentHashMap<String, Bitmap>();
    pool = Executors.newFixedThreadPool(5);
  }

  public void setPlaceholder(Bitmap bmp) {
    placeholder = bmp;
  }

  public Bitmap getBitmapFromCache(String url) {
    if (cache.containsKey(url)) {
      return cache.get(url);
    }

    return null;
  }

  public void queueJob(final String url, final ImageView imageView) {
    /* Create handler in UI thread. */
    final Handler handler = new Handler() {
      @Override
      public void handleMessage(Message msg) {
        String tag = imageViews.get(imageView);
        if (tag != null && tag.equals(url)) {
          if (msg.obj != null) {
            imageView.setImageBitmap((Bitmap) msg.obj);
          } else {
            imageView.setImageBitmap(placeholder);
            Log.d(null, "fail " + url);
          }
        }
      }
    };

    pool.submit(new Runnable() {
      public void run() {
        final Bitmap bmp = getPreview(url);
        Message message = Message.obtain();
        message.obj = bmp;
        Log.d(null, "Item downloaded: " + url);

        handler.sendMessage(message);
      }
    });
  }

  public void loadBitmap(final String url, final ImageView imageView) {
    imageViews.put(imageView, url);
    Bitmap bitmap = getBitmapFromCache(url);

    // check in UI thread, so no concurrency issues
    if (bitmap != null) {
      Log.d(null, "Item loaded from cache: " + url);
      imageView.setImageBitmap(bitmap);
    } else {
      imageView.setImageBitmap(placeholder);
      queueJob(url, imageView);
    }
  }

  public void clearCache() {
    cache.clear();
  }

  private Bitmap getPreview(String url) {
    File image = new File(url);
    int size = 72;

    InputStream photoStream = null;
    Bitmap mBitmap = null;
    try {
      photoStream = new FileInputStream(image);
      BitmapFactory.Options opts = new BitmapFactory.Options();
      opts.inJustDecodeBounds = true;
      opts.inSampleSize = 1;

      mBitmap = BitmapFactory.decodeStream(photoStream, null, opts);
      if (opts.outWidth > opts.outHeight && opts.outWidth > size) {
        opts.inSampleSize = opts.outWidth / size;
      } else if (opts.outWidth < opts.outHeight && opts.outHeight > size) {
        opts.inSampleSize = opts.outHeight / size;
      }
      if (opts.inSampleSize < 1) {
        opts.inSampleSize = 1;
      }
      opts.inJustDecodeBounds = false;
      photoStream.close();
      photoStream = new FileInputStream(image);
      mBitmap = BitmapFactory.decodeStream(photoStream, null, opts);
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (photoStream != null) {
        try {
          photoStream.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
    cache.put(url, mBitmap);

    return mBitmap;
  }
}

Java Source Code List

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