Android – Picasso Load image from filesystem

Here's what I created to hold the images that my app is currently displaying. Please note that the "Log" object in use here is my custom wrapper around the final Log class inside Android.

package com.wilson.android.library;

/*
 Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you 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.
*/
import java.io.IOException;

public class DrawableManager {
    private final Map<String, Drawable> drawableMap;

    public DrawableManager() {
        drawableMap = new HashMap<String, Drawable>();
    }

    public Drawable fetchDrawable(String urlString) {
        if (drawableMap.containsKey(urlString)) {
            return drawableMap.get(urlString);
        }

        Log.d(this.getClass().getSimpleName(), "image url:" + urlString);
        try {
            InputStream is = fetch(urlString);
            Drawable drawable = Drawable.createFromStream(is, "src");


            if (drawable != null) {
                drawableMap.put(urlString, drawable);
                Log.d(this.getClass().getSimpleName(), "got a thumbnail drawable: " + drawable.getBounds() + ", "
                        + drawable.getIntrinsicHeight() + "," + drawable.getIntrinsicWidth() + ", "
                        + drawable.getMinimumHeight() + "," + drawable.getMinimumWidth());
            } else {
              Log.w(this.getClass().getSimpleName(), "could not get thumbnail");
            }

            return drawable;
        } catch (MalformedURLException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        } catch (IOException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        }
    }

    public void fetchDrawableOnThread(final String urlString, final ImageView imageView) {
        if (drawableMap.containsKey(urlString)) {
            imageView.setImageDrawable(drawableMap.get(urlString));
        }

        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message message) {
                imageView.setImageDrawable((Drawable) message.obj);
            }
        };

        Thread thread = new Thread() {
            @Override
            public void run() {
                //TODO : set imageView to a "pending" image
                Drawable drawable = fetchDrawable(urlString);
                Message message = handler.obtainMessage(1, drawable);
                handler.sendMessage(message);
            }
        };
        thread.start();
    }

    private InputStream fetch(String urlString) throws MalformedURLException, IOException {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpGet request = new HttpGet(urlString);
        HttpResponse response = httpClient.execute(request);
        return response.getEntity().getContent();
    }
}

Thanks to Code Shogun, whose code I adapted to my situation.

Let your activity implementOnClickListener as usual:

public class SelectFilterActivity extends Activity implements OnClickListener {

  private static final int SWIPE_MIN_DISTANCE = 120;
  private static final int SWIPE_MAX_OFF_PATH = 250;
  private static final int SWIPE_THRESHOLD_VELOCITY = 200;
  private GestureDetector gestureDetector;
  View.OnTouchListener gestureListener;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    /* ... */

    // Gesture detection
    gestureDetector = new GestureDetector(this, new MyGestureDetector());
    gestureListener = new View.OnTouchListener() {
      public boolean onTouch(View v, MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
      }
    };

  }

  class MyGestureDetector extends SimpleOnGestureListener {
    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
      try {
        if (Math.abs(e1.getY() - e2.getY()) > SWIPE_MAX_OFF_PATH)
          return false;
        // right to left swipe
        if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
          Toast.makeText(SelectFilterActivity.this, "Left Swipe", Toast.LENGTH_SHORT).show();
        } else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
          Toast.makeText(SelectFilterActivity.this, "Right Swipe", Toast.LENGTH_SHORT).show();
        }
      } catch (Exception e) {
         // nothing
      }
      return false;
    }

    @Override
    public boolean onDown(MotionEvent e) {
      return true;
    }
  }
}

Attach your gesture listener to all the views you add to the main layout;

// Do this for each view added to the grid
imageView.setOnClickListener(SelectFilterActivity.this); 
imageView.setOnTouchListener(gestureListener);

Watch in awe as your overridden methods are hit, both the onClick(View v) of the activity and the onFling of the gesture listener.

public void onClick(View v) {
  Filter f = (Filter) v.getTag();
  FilterFullscreenActivity.show(this, input, f);
}

The post 'fling' dance is optional but encouraged.