sg.com.utrix.skeleton.app.sample.util.ImageLoader.java Source code

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/*
 * Copyright 2012 Google Inc.
 *
 * 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 sg.com.utrix.skeleton.app.sample.util;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.TransitionDrawable;
import android.net.http.AndroidHttpClient;
import android.os.Build;
import android.os.Environment;
import android.support.v4.app.FragmentActivity;
import android.widget.ImageView;

import com.android.volley.Cache;
import com.android.volley.Network;
import com.android.volley.RequestQueue;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.BasicNetwork;
import com.android.volley.toolbox.DiskBasedCache;
import com.android.volley.toolbox.HttpClientStack;
import com.android.volley.toolbox.HurlStack;

import java.io.File;
import java.util.ArrayList;

/**
 * A class that wraps up remote image loading requests using the Volley library combined with a
 * memory cache. An single instance of this class should be created once when your Activity or
 * Fragment is created, then use {@link #get(String, android.widget.ImageView)} or one of
 * the variations to queue the image to be fetched and loaded from the network. Loading images
 * in a {@link android.widget.ListView} or {@link android.widget.GridView} is also supported but
 * you must store the {@link com.android.volley.Request} in your ViewHolder type class and pass it
 * into loadImage to ensure the request is canceled as views are recycled.
 */
public class ImageLoader extends com.android.volley.toolbox.ImageLoader {
    private static final ColorDrawable transparentDrawable = new ColorDrawable(android.R.color.transparent);
    //private static final int HALF_FADE_IN_TIME = UIUtils.ANIMATION_FADE_IN_TIME / 2;
    private static final int HALF_FADE_IN_TIME = 0;

    private static final String CACHE_DIR = "images";

    private Resources mResources;
    private ArrayList<Drawable> mPlaceHolderDrawables;
    private boolean mFadeInImage = true;
    private int mMaxImageHeight = 0;
    private int mMaxImageWidth = 0;
    public static final int ANIMATION_FADE_IN_TIME = 250;

    /**
     * Creates an ImageLoader with Bitmap memory cache. No default placeholder image will be shown
     * while the image is being fetched and loaded.
     */
    public ImageLoader(Activity activity) {
        super(newRequestQueue(activity), BitmapCache.getInstance(activity.getFragmentManager()));
        mResources = activity.getResources();
    }

    /**
     * Creates an ImageLoader with Bitmap memory cache and a default placeholder image while the
     * image is being fetched and loaded.
     */
    public ImageLoader(Activity activity, int defaultPlaceHolderResId) {
        super(newRequestQueue(activity), BitmapCache.getInstance(activity.getFragmentManager()));
        mResources = activity.getResources();
        mPlaceHolderDrawables = new ArrayList<Drawable>(1);
        mPlaceHolderDrawables
                .add(defaultPlaceHolderResId == -1 ? null : mResources.getDrawable(defaultPlaceHolderResId));
    }

    /**
     * Creates an ImageLoader with Bitmap memory cache and a list of default placeholder drawables.
     */
    public ImageLoader(Activity activity, ArrayList<Drawable> placeHolderDrawables) {
        super(newRequestQueue(activity), BitmapCache.getInstance(activity.getFragmentManager()));
        mResources = activity.getResources();
        mPlaceHolderDrawables = placeHolderDrawables;
    }

    /**
     * Starts processing requests on the {@link com.android.volley.RequestQueue}.
     */
    public void startProcessingQueue() {
        getRequestQueue().start();
    }

    /**
     * Stops processing requests on the {@link com.android.volley.RequestQueue}.
     */
    public void stopProcessingQueue() {
        getRequestQueue().stop();
    }

    public ImageLoader setFadeInImage(boolean fadeInImage) {
        mFadeInImage = fadeInImage;
        return this;
    }

    public ImageLoader setMaxImageSize(int maxImageWidth, int maxImageHeight) {
        mMaxImageWidth = maxImageWidth;
        mMaxImageHeight = maxImageHeight;
        return this;
    }

    public ImageLoader setMaxImageSize(int maxImageSize) {
        return setMaxImageSize(maxImageSize, maxImageSize);
    }

    public ImageContainer get(String requestUrl, ImageView imageView) {
        return get(requestUrl, imageView, 0);
    }

    public ImageContainer get(String requestUrl, ImageView imageView, int placeHolderIndex) {
        return get(requestUrl, imageView, mPlaceHolderDrawables.get(placeHolderIndex), mMaxImageWidth,
                mMaxImageHeight);
    }

    public ImageContainer get(String requestUrl, ImageView imageView, Drawable placeHolder) {
        return get(requestUrl, imageView, placeHolder, mMaxImageWidth, mMaxImageHeight);
    }

    public ImageContainer get(String requestUrl, ImageView imageView, Drawable placeHolder, int maxWidth,
            int maxHeight) {

        // Find any old image load request pending on this ImageView (in case this view was
        // recycled)
        ImageContainer imageContainer = imageView.getTag() != null && imageView.getTag() instanceof ImageContainer
                ? (ImageContainer) imageView.getTag()
                : null;

        // Find image url from prior request
        String recycledImageUrl = imageContainer != null ? imageContainer.getRequestUrl() : null;

        // If the new requestUrl is null or the new requestUrl is different to the previous
        // recycled requestUrl
        if (requestUrl == null || !requestUrl.equals(recycledImageUrl)) {
            if (imageContainer != null) {
                // Cancel previous image request
                imageContainer.cancelRequest();
                imageView.setTag(null);
            }
            if (requestUrl != null) {
                // Queue new request to fetch image
                imageContainer = get(requestUrl, getImageListener(mResources, imageView, placeHolder, mFadeInImage),
                        maxWidth, maxHeight);
                // Store request in ImageView tag
                imageView.setTag(imageContainer);
            } else {
                imageView.setImageDrawable(placeHolder);
                imageView.setTag(null);
            }
        }

        return imageContainer;
    }

    private static ImageListener getImageListener(final Resources resources, final ImageView imageView,
            final Drawable placeHolder, final boolean fadeInImage) {
        return new ImageListener() {
            @Override
            public void onResponse(ImageContainer response, boolean isImmediate) {
                imageView.setTag(null);
                if (response.getBitmap() != null) {
                    setImageBitmap(imageView, response.getBitmap(), resources, fadeInImage && !isImmediate);
                } else {
                    imageView.setImageDrawable(placeHolder);
                }
            }

            @Override
            public void onErrorResponse(VolleyError volleyError) {
            }
        };
    }

    private static RequestQueue newRequestQueue(Context context) {

        // On HC+ use HurlStack which is based on HttpURLConnection. Otherwise fall back on
        // AndroidHttpClient (based on Apache DefaultHttpClient) which should no longer be used
        // on newer platform versions where HttpURLConnection is simply better.
        Network network = new BasicNetwork(hasHoneycomb() ? new HurlStack()
                : new HttpClientStack(AndroidHttpClient.newInstance(NetUtils.getUserAgent(context))));

        Cache cache = new DiskBasedCache(getDiskCacheDir(context, CACHE_DIR));
        RequestQueue queue = new RequestQueue(cache, network);
        queue.start();
        return queue;
    }

    /**
     * Sets a {@link android.graphics.Bitmap} to an {@link android.widget.ImageView} using a
     * fade-in animation. If there is a {@link android.graphics.drawable.Drawable} already set on
     * the ImageView then use that as the image to fade from. Otherwise fade in from a transparent
     * Drawable.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
    private static void setImageBitmap(final ImageView imageView, final Bitmap bitmap, Resources resources,
            boolean fadeIn) {

        // If we're fading in and on HC MR1+
        if (fadeIn && hasHoneycombMR1()) {
            // Use ViewPropertyAnimator to run a simple fade in + fade out animation to update the
            // ImageView
            imageView.animate().scaleY(0.95f).scaleX(0.95f).alpha(0f)
                    .setDuration(imageView.getDrawable() == null ? 0 : HALF_FADE_IN_TIME)
                    .setListener(new AnimatorListenerAdapter() {
                        @Override
                        public void onAnimationEnd(Animator animation) {
                            imageView.setImageBitmap(bitmap);
                            imageView.animate().alpha(1f).scaleY(1f).scaleX(1f).setDuration(HALF_FADE_IN_TIME)
                                    .setListener(null);
                        }
                    });
        } else if (fadeIn) {
            // Otherwise use a TransitionDrawable to fade in
            Drawable initialDrawable;
            if (imageView.getDrawable() != null) {
                initialDrawable = imageView.getDrawable();
            } else {
                initialDrawable = transparentDrawable;
            }
            BitmapDrawable bitmapDrawable = new BitmapDrawable(resources, bitmap);
            // Use TransitionDrawable to fade in
            final TransitionDrawable td = new TransitionDrawable(
                    new Drawable[] { initialDrawable, bitmapDrawable });
            imageView.setImageDrawable(td);
            td.startTransition(ANIMATION_FADE_IN_TIME);
        } else {
            // No fade in, just set bitmap directly
            imageView.setImageBitmap(bitmap);
        }
    }

    /**
     * Get a usable cache directory (external if available, internal otherwise).
     *
     * @param context The context to use
     * @param uniqueName A unique directory name to append to the cache dir
     * @return The cache dir
     */
    public static File getDiskCacheDir(Context context, String uniqueName) {
        // Check if media is mounted or storage is built-in, if so, try and use external cache dir
        // otherwise use internal cache dir

        // TODO: getCacheDir() should be moved to a background thread as it attempts to create the
        // directory if it does not exist (no disk access should happen on the main/UI thread).
        final String cachePath = Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())
                || !Environment.isExternalStorageRemovable() ? getExternalCacheDir(context).getPath()
                        : context.getCacheDir().getPath();

        return new File(cachePath + File.separator + uniqueName);
    }

    /**
     * Get the external app cache directory.
     *
     * @param context The context to use
     * @return The external cache dir
     */
    private static File getExternalCacheDir(Context context) {
        // TODO: This needs to be moved to a background thread to ensure no disk access on the
        // main/UI thread as unfortunately getExternalCacheDir() calls mkdirs() for us (even
        // though the Volley library will later try and call mkdirs() as well from a background
        // thread).
        return context.getExternalCacheDir();
    }

    /**
     * Interface an activity can implement to provide an ImageLoader to its children fragments.
     */
    public interface ImageLoaderProvider {
        public ImageLoader getImageLoaderInstance();
    }

    public static boolean hasHoneycomb() {
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB;
    }

    public static boolean hasHoneycombMR1() {
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR1;
    }

}