mTHMMY/app/src/main/java/gr/thmmy/mthmmy/utils/ImageController.java

package gr.thmmy.mthmmy.utils;

import android.app.Application;
import android.text.TextUtils;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.Volley;

public class ImageController extends Application {

    private static final String TAG = ImageController.class.getSimpleName();
    private static ImageController mInstance;
    private RequestQueue mRequestQueue;
    private ImageLoader mImageLoader;

    public static synchronized ImageController getInstance() {
        return mInstance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    private RequestQueue getRequestQueue() {
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }

    public ImageLoader getImageLoader() {
        getRequestQueue();
        if (mImageLoader == null) {
            mImageLoader = new ImageLoader(this.mRequestQueue,
                    new LruBitmapCache());
        }
        return this.mImageLoader;
    }

    public <T> void addToRequestQueue(Request<T> req, String tag) {
        // set the default tag if tag is empty
        req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
        getRequestQueue().add(req);
    }

    public <T> void addToRequestQueue(Request<T> req) {
        req.setTag(TAG);
        getRequestQueue().add(req);
    }

    public void cancelPendingRequests(){
        mRequestQueue.cancelAll(new RequestQueue.RequestFilter() {
            @Override
            public boolean apply(Request<?> request) {
                return true;
            }
        });
    }
}