Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 1 | /** |
| 2 | * Copyright (C) 2013 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package com.android.volley.toolbox; |
| 17 | |
| 18 | import android.graphics.Bitmap; |
| 19 | import android.graphics.Bitmap.Config; |
| 20 | import android.os.Handler; |
| 21 | import android.os.Looper; |
| 22 | import android.widget.ImageView; |
| 23 | |
| 24 | import com.android.volley.Request; |
| 25 | import com.android.volley.RequestQueue; |
| 26 | import com.android.volley.Response.ErrorListener; |
| 27 | import com.android.volley.Response.Listener; |
| 28 | import com.android.volley.VolleyError; |
| 29 | import com.android.volley.toolbox.ImageRequest; |
| 30 | |
| 31 | import java.util.HashMap; |
| 32 | import java.util.LinkedList; |
| 33 | |
| 34 | /** |
| 35 | * Helper that handles loading and caching images from remote URLs. |
| 36 | * |
| 37 | * The simple way to use this class is to call {@link ImageLoader#get(String, ImageListener)} |
| 38 | * and to pass in the default image listener provided by |
| 39 | * {@link ImageLoader#getImageListener(ImageView, int, int)}. Note that all function calls to |
| 40 | * this class must be made from the main thead, and all responses will be delivered to the main |
| 41 | * thread as well. |
| 42 | */ |
| 43 | public class ImageLoader { |
| 44 | /** RequestQueue for dispatching ImageRequests onto. */ |
| 45 | private final RequestQueue mRequestQueue; |
| 46 | |
| 47 | /** Amount of time to wait after first response arrives before delivering all responses. */ |
| 48 | private int mBatchResponseDelayMs = 100; |
| 49 | |
| 50 | /** The cache implementation to be used as an L1 cache before calling into volley. */ |
| 51 | private final ImageCache mCache; |
| 52 | |
| 53 | /** |
| 54 | * HashMap of Cache keys -> BatchedImageRequest used to track in-flight requests so |
| 55 | * that we can coalesce multiple requests to the same URL into a single network request. |
| 56 | */ |
| 57 | private final HashMap<String, BatchedImageRequest> mInFlightRequests = |
| 58 | new HashMap<String, BatchedImageRequest>(); |
| 59 | |
| 60 | /** HashMap of the currently pending responses (waiting to be delivered). */ |
| 61 | private final HashMap<String, BatchedImageRequest> mBatchedResponses = |
| 62 | new HashMap<String, BatchedImageRequest>(); |
| 63 | |
| 64 | /** Handler to the main thread. */ |
| 65 | private final Handler mHandler = new Handler(Looper.getMainLooper()); |
| 66 | |
| 67 | /** Runnable for in-flight response delivery. */ |
| 68 | private Runnable mRunnable; |
| 69 | |
| 70 | /** |
| 71 | * Simple cache adapter interface. If provided to the ImageLoader, it |
| 72 | * will be used as an L1 cache before dispatch to Volley. Implementations |
| 73 | * must not block. Implementation with an LruCache is recommended. |
| 74 | */ |
| 75 | public interface ImageCache { |
| 76 | public Bitmap getBitmap(String url); |
| 77 | public void putBitmap(String url, Bitmap bitmap); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Constructs a new ImageLoader. |
| 82 | * @param queue The RequestQueue to use for making image requests. |
| 83 | * @param imageCache The cache to use as an L1 cache. |
| 84 | */ |
| 85 | public ImageLoader(RequestQueue queue, ImageCache imageCache) { |
| 86 | mRequestQueue = queue; |
| 87 | mCache = imageCache; |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * The default implementation of ImageListener which handles basic functionality |
| 92 | * of showing a default image until the network response is received, at which point |
| 93 | * it will switch to either the actual image or the error image. |
| 94 | * @param imageView The imageView that the listener is associated with. |
| 95 | * @param defaultImageResId Default image resource ID to use, or 0 if it doesn't exist. |
| 96 | * @param errorImageResId Error image resource ID to use, or 0 if it doesn't exist. |
| 97 | */ |
| 98 | public static ImageListener getImageListener(final ImageView view, |
| 99 | final int defaultImageResId, final int errorImageResId) { |
| 100 | return new ImageListener() { |
| 101 | @Override |
| 102 | public void onErrorResponse(VolleyError error) { |
| 103 | if (errorImageResId != 0) { |
| 104 | view.setImageResource(errorImageResId); |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | @Override |
| 109 | public void onResponse(ImageContainer response, boolean isImmediate) { |
| 110 | if (response.getBitmap() != null) { |
| 111 | view.setImageBitmap(response.getBitmap()); |
| 112 | } else if (defaultImageResId != 0) { |
| 113 | view.setImageResource(defaultImageResId); |
| 114 | } |
| 115 | } |
| 116 | }; |
| 117 | } |
| 118 | |
| 119 | /** |
| 120 | * Interface for the response handlers on image requests. |
| 121 | * |
| 122 | * The call flow is this: |
| 123 | * 1. Upon being attached to a request, onResponse(response, true) will |
| 124 | * be invoked to reflect any cached data that was already available. If the |
| 125 | * data was available, response.getBitmap() will be non-null. |
| 126 | * |
| 127 | * 2. After a network response returns, only one of the following cases will happen: |
| 128 | * - onResponse(response, false) will be called if the image was loaded. |
| 129 | * or |
| 130 | * - onErrorResponse will be called if there was an error loading the image. |
| 131 | */ |
| 132 | public interface ImageListener extends ErrorListener { |
| 133 | /** |
| 134 | * Listens for non-error changes to the loading of the image request. |
| 135 | * |
| 136 | * @param response Holds all information pertaining to the request, as well |
| 137 | * as the bitmap (if it is loaded). |
| 138 | * @param isImmediate True if this was called during ImageLoader.get() variants. |
| 139 | * This can be used to differentiate between a cached image loading and a network |
| 140 | * image loading in order to, for example, run an animation to fade in network loaded |
| 141 | * images. |
| 142 | */ |
| 143 | public void onResponse(ImageContainer response, boolean isImmediate); |
| 144 | } |
| 145 | |
| 146 | /** |
andaagar | 285d472 | 2013-05-22 19:28:14 +0200 | [diff] [blame] | 147 | * Checks if the item is available in the cache. |
| 148 | * @param requestUrl The url of the remote image |
| 149 | * @param maxWidth The maximum width of the returned image. |
| 150 | * @param maxHeight The maximum height of the returned image. |
| 151 | * @return True if the item exists in cache, false otherwise. |
| 152 | */ |
| 153 | public boolean isCached(String requestUrl, int maxWidth, int maxHeight) { |
| 154 | throwIfNotOnMainThread(); |
| 155 | |
| 156 | String cacheKey = getCacheKey(requestUrl, maxWidth, maxHeight); |
| 157 | return mCache.getBitmap(cacheKey) != null; |
| 158 | } |
| 159 | |
| 160 | /** |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 161 | * Returns an ImageContainer for the requested URL. |
| 162 | * |
| 163 | * The ImageContainer will contain either the specified default bitmap or the loaded bitmap. |
| 164 | * If the default was returned, the {@link ImageLoader} will be invoked when the |
| 165 | * request is fulfilled. |
| 166 | * |
| 167 | * @param requestUrl The URL of the image to be loaded. |
| 168 | * @param defaultImage Optional default image to return until the actual image is loaded. |
| 169 | */ |
| 170 | public ImageContainer get(String requestUrl, final ImageListener listener) { |
| 171 | return get(requestUrl, listener, 0, 0); |
| 172 | } |
| 173 | |
| 174 | /** |
| 175 | * Issues a bitmap request with the given URL if that image is not available |
| 176 | * in the cache, and returns a bitmap container that contains all of the data |
| 177 | * relating to the request (as well as the default image if the requested |
| 178 | * image is not available). |
| 179 | * @param requestUrl The url of the remote image |
| 180 | * @param imageListener The listener to call when the remote image is loaded |
| 181 | * @param maxWidth The maximum width of the returned image. |
| 182 | * @param maxHeight The maximum height of the returned image. |
| 183 | * @return A container object that contains all of the properties of the request, as well as |
| 184 | * the currently available image (default if remote is not loaded). |
| 185 | */ |
| 186 | public ImageContainer get(String requestUrl, ImageListener imageListener, |
| 187 | int maxWidth, int maxHeight) { |
| 188 | // only fulfill requests that were initiated from the main thread. |
| 189 | throwIfNotOnMainThread(); |
| 190 | |
| 191 | final String cacheKey = getCacheKey(requestUrl, maxWidth, maxHeight); |
| 192 | |
| 193 | // Try to look up the request in the cache of remote images. |
| 194 | Bitmap cachedBitmap = mCache.getBitmap(cacheKey); |
| 195 | if (cachedBitmap != null) { |
| 196 | // Return the cached bitmap. |
| 197 | ImageContainer container = new ImageContainer(cachedBitmap, requestUrl, null, null); |
| 198 | imageListener.onResponse(container, true); |
| 199 | return container; |
| 200 | } |
| 201 | |
| 202 | // The bitmap did not exist in the cache, fetch it! |
| 203 | ImageContainer imageContainer = |
| 204 | new ImageContainer(null, requestUrl, cacheKey, imageListener); |
| 205 | |
| 206 | // Update the caller to let them know that they should use the default bitmap. |
| 207 | imageListener.onResponse(imageContainer, true); |
| 208 | |
| 209 | // Check to see if a request is already in-flight. |
| 210 | BatchedImageRequest request = mInFlightRequests.get(cacheKey); |
| 211 | if (request != null) { |
| 212 | // If it is, add this request to the list of listeners. |
| 213 | request.addContainer(imageContainer); |
| 214 | return imageContainer; |
| 215 | } |
| 216 | |
| 217 | // The request is not already in flight. Send the new request to the network and |
| 218 | // track it. |
| 219 | Request<?> newRequest = |
| 220 | new ImageRequest(requestUrl, new Listener<Bitmap>() { |
| 221 | @Override |
| 222 | public void onResponse(Bitmap response) { |
| 223 | onGetImageSuccess(cacheKey, response); |
| 224 | } |
| 225 | }, maxWidth, maxHeight, |
| 226 | Config.RGB_565, new ErrorListener() { |
| 227 | @Override |
| 228 | public void onErrorResponse(VolleyError error) { |
| 229 | onGetImageError(cacheKey, error); |
| 230 | } |
| 231 | }); |
| 232 | |
| 233 | mRequestQueue.add(newRequest); |
| 234 | mInFlightRequests.put(cacheKey, |
| 235 | new BatchedImageRequest(newRequest, imageContainer)); |
| 236 | return imageContainer; |
| 237 | } |
| 238 | |
| 239 | /** |
| 240 | * Sets the amount of time to wait after the first response arrives before delivering all |
| 241 | * responses. Batching can be disabled entirely by passing in 0. |
| 242 | * @param newBatchedResponseDelayMs The time in milliseconds to wait. |
| 243 | */ |
| 244 | public void setBatchedResponseDelay(int newBatchedResponseDelayMs) { |
| 245 | mBatchResponseDelayMs = newBatchedResponseDelayMs; |
| 246 | } |
| 247 | |
| 248 | /** |
| 249 | * Handler for when an image was successfully loaded. |
| 250 | * @param cacheKey The cache key that is associated with the image request. |
| 251 | * @param response The bitmap that was returned from the network. |
| 252 | */ |
| 253 | private void onGetImageSuccess(String cacheKey, Bitmap response) { |
| 254 | // cache the image that was fetched. |
| 255 | mCache.putBitmap(cacheKey, response); |
| 256 | |
| 257 | // remove the request from the list of in-flight requests. |
| 258 | BatchedImageRequest request = mInFlightRequests.remove(cacheKey); |
| 259 | |
| 260 | if (request != null) { |
| 261 | // Update the response bitmap. |
| 262 | request.mResponseBitmap = response; |
| 263 | |
| 264 | // Send the batched response |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 265 | batchResponse(cacheKey, request); |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 266 | } |
| 267 | } |
| 268 | |
| 269 | /** |
| 270 | * Handler for when an image failed to load. |
| 271 | * @param cacheKey The cache key that is associated with the image request. |
| 272 | */ |
| 273 | private void onGetImageError(String cacheKey, VolleyError error) { |
| 274 | // Notify the requesters that something failed via a null result. |
| 275 | // Remove this request from the list of in-flight requests. |
| 276 | BatchedImageRequest request = mInFlightRequests.remove(cacheKey); |
| 277 | |
| 278 | if (request != null) { |
Andrew Sutherland | ee9d450 | 2014-03-29 18:09:47 -0500 | [diff] [blame] | 279 | // Set the error for this request |
| 280 | request.setError(error); |
| 281 | |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 282 | // Send the batched response |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 283 | batchResponse(cacheKey, request); |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 284 | } |
| 285 | } |
| 286 | |
| 287 | /** |
| 288 | * Container object for all of the data surrounding an image request. |
| 289 | */ |
| 290 | public class ImageContainer { |
| 291 | /** |
| 292 | * The most relevant bitmap for the container. If the image was in cache, the |
| 293 | * Holder to use for the final bitmap (the one that pairs to the requested URL). |
| 294 | */ |
| 295 | private Bitmap mBitmap; |
| 296 | |
| 297 | private final ImageListener mListener; |
| 298 | |
| 299 | /** The cache key that was associated with the request */ |
| 300 | private final String mCacheKey; |
| 301 | |
| 302 | /** The request URL that was specified */ |
| 303 | private final String mRequestUrl; |
| 304 | |
| 305 | /** |
| 306 | * Constructs a BitmapContainer object. |
| 307 | * @param bitmap The final bitmap (if it exists). |
| 308 | * @param requestUrl The requested URL for this container. |
| 309 | * @param cacheKey The cache key that identifies the requested URL for this container. |
| 310 | */ |
| 311 | public ImageContainer(Bitmap bitmap, String requestUrl, |
| 312 | String cacheKey, ImageListener listener) { |
| 313 | mBitmap = bitmap; |
| 314 | mRequestUrl = requestUrl; |
| 315 | mCacheKey = cacheKey; |
| 316 | mListener = listener; |
| 317 | } |
| 318 | |
| 319 | /** |
| 320 | * Releases interest in the in-flight request (and cancels it if no one else is listening). |
| 321 | */ |
| 322 | public void cancelRequest() { |
| 323 | if (mListener == null) { |
| 324 | return; |
| 325 | } |
| 326 | |
| 327 | BatchedImageRequest request = mInFlightRequests.get(mCacheKey); |
| 328 | if (request != null) { |
| 329 | boolean canceled = request.removeContainerAndCancelIfNecessary(this); |
| 330 | if (canceled) { |
| 331 | mInFlightRequests.remove(mCacheKey); |
| 332 | } |
| 333 | } else { |
| 334 | // check to see if it is already batched for delivery. |
| 335 | request = mBatchedResponses.get(mCacheKey); |
| 336 | if (request != null) { |
| 337 | request.removeContainerAndCancelIfNecessary(this); |
| 338 | if (request.mContainers.size() == 0) { |
| 339 | mBatchedResponses.remove(mCacheKey); |
| 340 | } |
| 341 | } |
| 342 | } |
| 343 | } |
| 344 | |
| 345 | /** |
| 346 | * Returns the bitmap associated with the request URL if it has been loaded, null otherwise. |
| 347 | */ |
| 348 | public Bitmap getBitmap() { |
| 349 | return mBitmap; |
| 350 | } |
| 351 | |
| 352 | /** |
| 353 | * Returns the requested URL for this container. |
| 354 | */ |
| 355 | public String getRequestUrl() { |
| 356 | return mRequestUrl; |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | /** |
| 361 | * Wrapper class used to map a Request to the set of active ImageContainer objects that are |
| 362 | * interested in its results. |
| 363 | */ |
| 364 | private class BatchedImageRequest { |
| 365 | /** The request being tracked */ |
| 366 | private final Request<?> mRequest; |
| 367 | |
| 368 | /** The result of the request being tracked by this item */ |
| 369 | private Bitmap mResponseBitmap; |
| 370 | |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 371 | /** Error if one occurred for this response */ |
| 372 | private VolleyError mError; |
| 373 | |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 374 | /** List of all of the active ImageContainers that are interested in the request */ |
| 375 | private final LinkedList<ImageContainer> mContainers = new LinkedList<ImageContainer>(); |
| 376 | |
| 377 | /** |
| 378 | * Constructs a new BatchedImageRequest object |
| 379 | * @param request The request being tracked |
| 380 | * @param container The ImageContainer of the person who initiated the request. |
| 381 | */ |
| 382 | public BatchedImageRequest(Request<?> request, ImageContainer container) { |
| 383 | mRequest = request; |
| 384 | mContainers.add(container); |
| 385 | } |
| 386 | |
| 387 | /** |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 388 | * Set the error for this response |
| 389 | */ |
| 390 | public void setError(VolleyError error) { |
| 391 | mError = error; |
| 392 | } |
| 393 | |
| 394 | /** |
| 395 | * Get the error for this response |
| 396 | */ |
| 397 | public VolleyError getError() { |
| 398 | return mError; |
| 399 | } |
| 400 | |
| 401 | /** |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 402 | * Adds another ImageContainer to the list of those interested in the results of |
| 403 | * the request. |
| 404 | */ |
| 405 | public void addContainer(ImageContainer container) { |
| 406 | mContainers.add(container); |
| 407 | } |
| 408 | |
| 409 | /** |
| 410 | * Detatches the bitmap container from the request and cancels the request if no one is |
| 411 | * left listening. |
| 412 | * @param container The container to remove from the list |
| 413 | * @return True if the request was canceled, false otherwise. |
| 414 | */ |
| 415 | public boolean removeContainerAndCancelIfNecessary(ImageContainer container) { |
| 416 | mContainers.remove(container); |
| 417 | if (mContainers.size() == 0) { |
| 418 | mRequest.cancel(); |
| 419 | return true; |
| 420 | } |
| 421 | return false; |
| 422 | } |
| 423 | } |
| 424 | |
| 425 | /** |
| 426 | * Starts the runnable for batched delivery of responses if it is not already started. |
| 427 | * @param cacheKey The cacheKey of the response being delivered. |
| 428 | * @param request The BatchedImageRequest to be delivered. |
| 429 | * @param error The volley error associated with the request (if applicable). |
| 430 | */ |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 431 | private void batchResponse(String cacheKey, BatchedImageRequest request) { |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 432 | mBatchedResponses.put(cacheKey, request); |
| 433 | // If we don't already have a batch delivery runnable in flight, make a new one. |
| 434 | // Note that this will be used to deliver responses to all callers in mBatchedResponses. |
| 435 | if (mRunnable == null) { |
| 436 | mRunnable = new Runnable() { |
| 437 | @Override |
| 438 | public void run() { |
| 439 | for (BatchedImageRequest bir : mBatchedResponses.values()) { |
| 440 | for (ImageContainer container : bir.mContainers) { |
| 441 | // If one of the callers in the batched request canceled the request |
| 442 | // after the response was received but before it was delivered, |
| 443 | // skip them. |
| 444 | if (container.mListener == null) { |
| 445 | continue; |
| 446 | } |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 447 | if (bir.getError() == null) { |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 448 | container.mBitmap = bir.mResponseBitmap; |
| 449 | container.mListener.onResponse(container, false); |
| 450 | } else { |
Cameron Ketcham | dc53552 | 2013-05-23 17:40:08 -0400 | [diff] [blame] | 451 | container.mListener.onErrorResponse(bir.getError()); |
Aurash Mahbod | d62a616 | 2013-05-08 00:26:10 -0700 | [diff] [blame] | 452 | } |
| 453 | } |
| 454 | } |
| 455 | mBatchedResponses.clear(); |
| 456 | mRunnable = null; |
| 457 | } |
| 458 | |
| 459 | }; |
| 460 | // Post the runnable. |
| 461 | mHandler.postDelayed(mRunnable, mBatchResponseDelayMs); |
| 462 | } |
| 463 | } |
| 464 | |
| 465 | private void throwIfNotOnMainThread() { |
| 466 | if (Looper.myLooper() != Looper.getMainLooper()) { |
| 467 | throw new IllegalStateException("ImageLoader must be invoked from the main thread."); |
| 468 | } |
| 469 | } |
| 470 | /** |
| 471 | * Creates a cache key for use with the L1 cache. |
| 472 | * @param url The URL of the request. |
| 473 | * @param maxWidth The max-width of the output. |
| 474 | * @param maxHeight The max-height of the output. |
| 475 | */ |
| 476 | private static String getCacheKey(String url, int maxWidth, int maxHeight) { |
| 477 | return new StringBuilder(url.length() + 12).append("#W").append(maxWidth) |
| 478 | .append("#H").append(maxHeight).append(url).toString(); |
| 479 | } |
| 480 | } |