| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * 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 com.example.android.bitmapfun.util; |
| |
| import com.example.android.bitmapfun.BuildConfig; |
| |
| import android.content.Context; |
| import android.content.res.Resources; |
| import android.graphics.Bitmap; |
| import android.graphics.BitmapFactory; |
| import android.graphics.drawable.BitmapDrawable; |
| import android.graphics.drawable.ColorDrawable; |
| import android.graphics.drawable.Drawable; |
| import android.graphics.drawable.TransitionDrawable; |
| import android.support.v4.app.FragmentActivity; |
| import android.support.v4.app.FragmentManager; |
| import android.util.Log; |
| import android.widget.ImageView; |
| |
| import java.lang.ref.WeakReference; |
| |
| /** |
| * This class wraps up completing some arbitrary long running work when loading a bitmap to an |
| * ImageView. It handles things like using a memory and disk cache, running the work in a background |
| * thread and setting a placeholder image. |
| */ |
| public abstract class ImageWorker { |
| private static final String TAG = "ImageWorker"; |
| private static final int FADE_IN_TIME = 200; |
| |
| private ImageCache mImageCache; |
| private ImageCache.ImageCacheParams mImageCacheParams; |
| private Bitmap mLoadingBitmap; |
| private boolean mFadeInBitmap = true; |
| private boolean mExitTasksEarly = false; |
| protected boolean mPauseWork = false; |
| private final Object mPauseWorkLock = new Object(); |
| |
| protected Resources mResources; |
| |
| private static final int MESSAGE_CLEAR = 0; |
| private static final int MESSAGE_INIT_DISK_CACHE = 1; |
| private static final int MESSAGE_FLUSH = 2; |
| private static final int MESSAGE_CLOSE = 3; |
| |
| protected ImageWorker(Context context) { |
| mResources = context.getResources(); |
| } |
| |
| /** |
| * Load an image specified by the data parameter into an ImageView (override |
| * {@link ImageWorker#processBitmap(Object)} to define the processing logic). A memory and |
| * disk cache will be used if an {@link ImageCache} has been added using |
| * {@link ImageWorker#addImageCache(FragmentManager, ImageCache.ImageCacheParams)}. If the |
| * image is found in the memory cache, it is set immediately, otherwise an {@link AsyncTask} |
| * will be created to asynchronously load the bitmap. |
| * |
| * @param data The URL of the image to download. |
| * @param imageView The ImageView to bind the downloaded image to. |
| */ |
| public void loadImage(Object data, ImageView imageView) { |
| if (data == null) { |
| return; |
| } |
| |
| BitmapDrawable value = null; |
| |
| if (mImageCache != null) { |
| value = mImageCache.getBitmapFromMemCache(String.valueOf(data)); |
| } |
| |
| if (value != null) { |
| // Bitmap found in memory cache |
| imageView.setImageDrawable(value); |
| } else if (cancelPotentialWork(data, imageView)) { |
| final BitmapWorkerTask task = new BitmapWorkerTask(imageView); |
| final AsyncDrawable asyncDrawable = |
| new AsyncDrawable(mResources, mLoadingBitmap, task); |
| imageView.setImageDrawable(asyncDrawable); |
| |
| // NOTE: This uses a custom version of AsyncTask that has been pulled from the |
| // framework and slightly modified. Refer to the docs at the top of the class |
| // for more info on what was changed. |
| task.executeOnExecutor(AsyncTask.DUAL_THREAD_EXECUTOR, data); |
| } |
| } |
| |
| /** |
| * Set placeholder bitmap that shows when the the background thread is running. |
| * |
| * @param bitmap |
| */ |
| public void setLoadingImage(Bitmap bitmap) { |
| mLoadingBitmap = bitmap; |
| } |
| |
| /** |
| * Set placeholder bitmap that shows when the the background thread is running. |
| * |
| * @param resId |
| */ |
| public void setLoadingImage(int resId) { |
| mLoadingBitmap = BitmapFactory.decodeResource(mResources, resId); |
| } |
| |
| /** |
| * Adds an {@link ImageCache} to this {@link ImageWorker} to handle disk and memory bitmap |
| * caching. |
| * @param fragmentManager |
| * @param cacheParams The cache parameters to use for the image cache. |
| */ |
| public void addImageCache(FragmentManager fragmentManager, |
| ImageCache.ImageCacheParams cacheParams) { |
| mImageCacheParams = cacheParams; |
| mImageCache = ImageCache.getInstance(fragmentManager, mImageCacheParams); |
| new CacheAsyncTask().execute(MESSAGE_INIT_DISK_CACHE); |
| } |
| |
| /** |
| * Adds an {@link ImageCache} to this {@link ImageWorker} to handle disk and memory bitmap |
| * caching. |
| * @param activity |
| * @param diskCacheDirectoryName See |
| * {@link ImageCache.ImageCacheParams#ImageCacheParams(Context, String)}. |
| */ |
| public void addImageCache(FragmentActivity activity, String diskCacheDirectoryName) { |
| mImageCacheParams = new ImageCache.ImageCacheParams(activity, diskCacheDirectoryName); |
| mImageCache = ImageCache.getInstance(activity.getSupportFragmentManager(), mImageCacheParams); |
| new CacheAsyncTask().execute(MESSAGE_INIT_DISK_CACHE); |
| } |
| |
| /** |
| * If set to true, the image will fade-in once it has been loaded by the background thread. |
| */ |
| public void setImageFadeIn(boolean fadeIn) { |
| mFadeInBitmap = fadeIn; |
| } |
| |
| public void setExitTasksEarly(boolean exitTasksEarly) { |
| mExitTasksEarly = exitTasksEarly; |
| setPauseWork(false); |
| } |
| |
| /** |
| * Subclasses should override this to define any processing or work that must happen to produce |
| * the final bitmap. This will be executed in a background thread and be long running. For |
| * example, you could resize a large bitmap here, or pull down an image from the network. |
| * |
| * @param data The data to identify which image to process, as provided by |
| * {@link ImageWorker#loadImage(Object, ImageView)} |
| * @return The processed bitmap |
| */ |
| protected abstract Bitmap processBitmap(Object data); |
| |
| /** |
| * @return The {@link ImageCache} object currently being used by this ImageWorker. |
| */ |
| protected ImageCache getImageCache() { |
| return mImageCache; |
| } |
| |
| /** |
| * Cancels any pending work attached to the provided ImageView. |
| * @param imageView |
| */ |
| public static void cancelWork(ImageView imageView) { |
| final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView); |
| if (bitmapWorkerTask != null) { |
| bitmapWorkerTask.cancel(true); |
| if (BuildConfig.DEBUG) { |
| final Object bitmapData = bitmapWorkerTask.data; |
| Log.d(TAG, "cancelWork - cancelled work for " + bitmapData); |
| } |
| } |
| } |
| |
| /** |
| * Returns true if the current work has been canceled or if there was no work in |
| * progress on this image view. |
| * Returns false if the work in progress deals with the same data. The work is not |
| * stopped in that case. |
| */ |
| public static boolean cancelPotentialWork(Object data, ImageView imageView) { |
| final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView); |
| |
| if (bitmapWorkerTask != null) { |
| final Object bitmapData = bitmapWorkerTask.data; |
| if (bitmapData == null || !bitmapData.equals(data)) { |
| bitmapWorkerTask.cancel(true); |
| if (BuildConfig.DEBUG) { |
| Log.d(TAG, "cancelPotentialWork - cancelled work for " + data); |
| } |
| } else { |
| // The same work is already in progress. |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * @param imageView Any imageView |
| * @return Retrieve the currently active work task (if any) associated with this imageView. |
| * null if there is no such task. |
| */ |
| private static BitmapWorkerTask getBitmapWorkerTask(ImageView imageView) { |
| if (imageView != null) { |
| final Drawable drawable = imageView.getDrawable(); |
| if (drawable instanceof AsyncDrawable) { |
| final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable; |
| return asyncDrawable.getBitmapWorkerTask(); |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * The actual AsyncTask that will asynchronously process the image. |
| */ |
| private class BitmapWorkerTask extends AsyncTask<Object, Void, BitmapDrawable> { |
| private Object data; |
| private final WeakReference<ImageView> imageViewReference; |
| |
| public BitmapWorkerTask(ImageView imageView) { |
| imageViewReference = new WeakReference<ImageView>(imageView); |
| } |
| |
| /** |
| * Background processing. |
| */ |
| @Override |
| protected BitmapDrawable doInBackground(Object... params) { |
| if (BuildConfig.DEBUG) { |
| Log.d(TAG, "doInBackground - starting work"); |
| } |
| |
| data = params[0]; |
| final String dataString = String.valueOf(data); |
| Bitmap bitmap = null; |
| BitmapDrawable drawable = null; |
| |
| // Wait here if work is paused and the task is not cancelled |
| synchronized (mPauseWorkLock) { |
| while (mPauseWork && !isCancelled()) { |
| try { |
| mPauseWorkLock.wait(); |
| } catch (InterruptedException e) {} |
| } |
| } |
| |
| // If the image cache is available and this task has not been cancelled by another |
| // thread and the ImageView that was originally bound to this task is still bound back |
| // to this task and our "exit early" flag is not set then try and fetch the bitmap from |
| // the cache |
| if (mImageCache != null && !isCancelled() && getAttachedImageView() != null |
| && !mExitTasksEarly) { |
| bitmap = mImageCache.getBitmapFromDiskCache(dataString); |
| } |
| |
| // If the bitmap was not found in the cache and this task has not been cancelled by |
| // another thread and the ImageView that was originally bound to this task is still |
| // bound back to this task and our "exit early" flag is not set, then call the main |
| // process method (as implemented by a subclass) |
| if (bitmap == null && !isCancelled() && getAttachedImageView() != null |
| && !mExitTasksEarly) { |
| bitmap = processBitmap(params[0]); |
| } |
| |
| // If the bitmap was processed and the image cache is available, then add the processed |
| // bitmap to the cache for future use. Note we don't check if the task was cancelled |
| // here, if it was, and the thread is still running, we may as well add the processed |
| // bitmap to our cache as it might be used again in the future |
| if (bitmap != null) { |
| if (Utils.hasHoneycomb()) { |
| // Running on Honeycomb or newer, so wrap in a standard BitmapDrawable |
| drawable = new BitmapDrawable(mResources, bitmap); |
| } else { |
| // Running on Gingerbread or older, so wrap in a RecyclingBitmapDrawable |
| // which will recycle automagically |
| drawable = new RecyclingBitmapDrawable(mResources, bitmap); |
| } |
| |
| if (mImageCache != null) { |
| mImageCache.addBitmapToCache(dataString, drawable); |
| } |
| } |
| |
| if (BuildConfig.DEBUG) { |
| Log.d(TAG, "doInBackground - finished work"); |
| } |
| |
| return drawable; |
| } |
| |
| /** |
| * Once the image is processed, associates it to the imageView |
| */ |
| @Override |
| protected void onPostExecute(BitmapDrawable value) { |
| // if cancel was called on this task or the "exit early" flag is set then we're done |
| if (isCancelled() || mExitTasksEarly) { |
| value = null; |
| } |
| |
| final ImageView imageView = getAttachedImageView(); |
| if (value != null && imageView != null) { |
| if (BuildConfig.DEBUG) { |
| Log.d(TAG, "onPostExecute - setting bitmap"); |
| } |
| setImageDrawable(imageView, value); |
| } |
| } |
| |
| @Override |
| protected void onCancelled(BitmapDrawable value) { |
| super.onCancelled(value); |
| synchronized (mPauseWorkLock) { |
| mPauseWorkLock.notifyAll(); |
| } |
| } |
| |
| /** |
| * Returns the ImageView associated with this task as long as the ImageView's task still |
| * points to this task as well. Returns null otherwise. |
| */ |
| private ImageView getAttachedImageView() { |
| final ImageView imageView = imageViewReference.get(); |
| final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView); |
| |
| if (this == bitmapWorkerTask) { |
| return imageView; |
| } |
| |
| return null; |
| } |
| } |
| |
| /** |
| * A custom Drawable that will be attached to the imageView while the work is in progress. |
| * Contains a reference to the actual worker task, so that it can be stopped if a new binding is |
| * required, and makes sure that only the last started worker process can bind its result, |
| * independently of the finish order. |
| */ |
| private static class AsyncDrawable extends BitmapDrawable { |
| private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference; |
| |
| public AsyncDrawable(Resources res, Bitmap bitmap, BitmapWorkerTask bitmapWorkerTask) { |
| super(res, bitmap); |
| bitmapWorkerTaskReference = |
| new WeakReference<BitmapWorkerTask>(bitmapWorkerTask); |
| } |
| |
| public BitmapWorkerTask getBitmapWorkerTask() { |
| return bitmapWorkerTaskReference.get(); |
| } |
| } |
| |
| /** |
| * Called when the processing is complete and the final drawable should be |
| * set on the ImageView. |
| * |
| * @param imageView |
| * @param drawable |
| */ |
| private void setImageDrawable(ImageView imageView, Drawable drawable) { |
| if (mFadeInBitmap) { |
| // Transition drawable with a transparent drawable and the final drawable |
| final TransitionDrawable td = |
| new TransitionDrawable(new Drawable[] { |
| new ColorDrawable(android.R.color.transparent), |
| drawable |
| }); |
| // Set background to loading bitmap |
| imageView.setBackgroundDrawable( |
| new BitmapDrawable(mResources, mLoadingBitmap)); |
| |
| imageView.setImageDrawable(td); |
| td.startTransition(FADE_IN_TIME); |
| } else { |
| imageView.setImageDrawable(drawable); |
| } |
| } |
| |
| /** |
| * Pause any ongoing background work. This can be used as a temporary |
| * measure to improve performance. For example background work could |
| * be paused when a ListView or GridView is being scrolled using a |
| * {@link android.widget.AbsListView.OnScrollListener} to keep |
| * scrolling smooth. |
| * <p> |
| * If work is paused, be sure setPauseWork(false) is called again |
| * before your fragment or activity is destroyed (for example during |
| * {@link android.app.Activity#onPause()}), or there is a risk the |
| * background thread will never finish. |
| */ |
| public void setPauseWork(boolean pauseWork) { |
| synchronized (mPauseWorkLock) { |
| mPauseWork = pauseWork; |
| if (!mPauseWork) { |
| mPauseWorkLock.notifyAll(); |
| } |
| } |
| } |
| |
| protected class CacheAsyncTask extends AsyncTask<Object, Void, Void> { |
| |
| @Override |
| protected Void doInBackground(Object... params) { |
| switch ((Integer)params[0]) { |
| case MESSAGE_CLEAR: |
| clearCacheInternal(); |
| break; |
| case MESSAGE_INIT_DISK_CACHE: |
| initDiskCacheInternal(); |
| break; |
| case MESSAGE_FLUSH: |
| flushCacheInternal(); |
| break; |
| case MESSAGE_CLOSE: |
| closeCacheInternal(); |
| break; |
| } |
| return null; |
| } |
| } |
| |
| protected void initDiskCacheInternal() { |
| if (mImageCache != null) { |
| mImageCache.initDiskCache(); |
| } |
| } |
| |
| protected void clearCacheInternal() { |
| if (mImageCache != null) { |
| mImageCache.clearCache(); |
| } |
| } |
| |
| protected void flushCacheInternal() { |
| if (mImageCache != null) { |
| mImageCache.flush(); |
| } |
| } |
| |
| protected void closeCacheInternal() { |
| if (mImageCache != null) { |
| mImageCache.close(); |
| mImageCache = null; |
| } |
| } |
| |
| public void clearCache() { |
| new CacheAsyncTask().execute(MESSAGE_CLEAR); |
| } |
| |
| public void flushCache() { |
| new CacheAsyncTask().execute(MESSAGE_FLUSH); |
| } |
| |
| public void closeCache() { |
| new CacheAsyncTask().execute(MESSAGE_CLOSE); |
| } |
| } |