The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2007 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 | |
| 17 | package android.widget; |
| 18 | |
| 19 | import android.os.Handler; |
| 20 | import android.os.HandlerThread; |
| 21 | import android.os.Looper; |
| 22 | import android.os.Message; |
| 23 | import android.util.Log; |
| 24 | |
| 25 | /** |
| 26 | * <p>A filter constrains data with a filtering pattern.</p> |
| 27 | * |
| 28 | * <p>Filters are usually created by {@link android.widget.Filterable} |
| 29 | * classes.</p> |
| 30 | * |
| 31 | * <p>Filtering operations performed by calling {@link #filter(CharSequence)} or |
| 32 | * {@link #filter(CharSequence, android.widget.Filter.FilterListener)} are |
| 33 | * performed asynchronously. When these methods are called, a filtering request |
| 34 | * is posted in a request queue and processed later. Any call to one of these |
| 35 | * methods will cancel any previous non-executed filtering request.</p> |
| 36 | * |
| 37 | * @see android.widget.Filterable |
| 38 | */ |
| 39 | public abstract class Filter { |
| 40 | private static final String LOG_TAG = "Filter"; |
| 41 | |
| 42 | private static final String THREAD_NAME = "Filter"; |
| 43 | private static final int FILTER_TOKEN = 0xD0D0F00D; |
| 44 | private static final int FINISH_TOKEN = 0xDEADBEEF; |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 45 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 46 | private Handler mThreadHandler; |
| 47 | private Handler mResultHandler; |
| 48 | |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 49 | private Delayer mDelayer; |
| 50 | |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 51 | private final Object mLock = new Object(); |
| 52 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 53 | /** |
| 54 | * <p>Creates a new asynchronous filter.</p> |
| 55 | */ |
| 56 | public Filter() { |
| 57 | mResultHandler = new ResultsHandler(); |
| 58 | } |
| 59 | |
| 60 | /** |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 61 | * Provide an interface that decides how long to delay the message for a given query. Useful |
| 62 | * for heuristics such as posting a delay for the delete key to avoid doing any work while the |
| 63 | * user holds down the delete key. |
| 64 | * |
| 65 | * @param delayer The delayer. |
| 66 | * @hide |
| 67 | */ |
| 68 | public void setDelayer(Delayer delayer) { |
| 69 | synchronized (mLock) { |
| 70 | mDelayer = delayer; |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | /** |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 75 | * <p>Starts an asynchronous filtering operation. Calling this method |
| 76 | * cancels all previous non-executed filtering requests and posts a new |
| 77 | * filtering request that will be executed later.</p> |
| 78 | * |
| 79 | * @param constraint the constraint used to filter the data |
| 80 | * |
| 81 | * @see #filter(CharSequence, android.widget.Filter.FilterListener) |
| 82 | */ |
| 83 | public final void filter(CharSequence constraint) { |
| 84 | filter(constraint, null); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * <p>Starts an asynchronous filtering operation. Calling this method |
| 89 | * cancels all previous non-executed filtering requests and posts a new |
| 90 | * filtering request that will be executed later.</p> |
| 91 | * |
| 92 | * <p>Upon completion, the listener is notified.</p> |
| 93 | * |
| 94 | * @param constraint the constraint used to filter the data |
| 95 | * @param listener a listener notified upon completion of the operation |
| 96 | * |
| 97 | * @see #filter(CharSequence) |
| 98 | * @see #performFiltering(CharSequence) |
| 99 | * @see #publishResults(CharSequence, android.widget.Filter.FilterResults) |
| 100 | */ |
| 101 | public final void filter(CharSequence constraint, FilterListener listener) { |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 102 | synchronized (mLock) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 103 | if (mThreadHandler == null) { |
Karl Rosaen | ab3ef10 | 2009-07-15 10:09:56 -0700 | [diff] [blame] | 104 | HandlerThread thread = new HandlerThread( |
| 105 | THREAD_NAME, android.os.Process.THREAD_PRIORITY_BACKGROUND); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 106 | thread.start(); |
| 107 | mThreadHandler = new RequestHandler(thread.getLooper()); |
| 108 | } |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 109 | |
| 110 | final long delay = (mDelayer == null) ? 0 : mDelayer.getPostingDelay(constraint); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 111 | |
| 112 | Message message = mThreadHandler.obtainMessage(FILTER_TOKEN); |
| 113 | |
| 114 | RequestArguments args = new RequestArguments(); |
| 115 | // make sure we use an immutable copy of the constraint, so that |
| 116 | // it doesn't change while the filter operation is in progress |
| 117 | args.constraint = constraint != null ? constraint.toString() : null; |
| 118 | args.listener = listener; |
| 119 | message.obj = args; |
| 120 | |
| 121 | mThreadHandler.removeMessages(FILTER_TOKEN); |
| 122 | mThreadHandler.removeMessages(FINISH_TOKEN); |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 123 | mThreadHandler.sendMessageDelayed(message, delay); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 124 | } |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * <p>Invoked in a worker thread to filter the data according to the |
| 129 | * constraint. Subclasses must implement this method to perform the |
| 130 | * filtering operation. Results computed by the filtering operation |
| 131 | * must be returned as a {@link android.widget.Filter.FilterResults} that |
| 132 | * will then be published in the UI thread through |
| 133 | * {@link #publishResults(CharSequence, |
| 134 | * android.widget.Filter.FilterResults)}.</p> |
| 135 | * |
| 136 | * <p><strong>Contract:</strong> When the constraint is null, the original |
| 137 | * data must be restored.</p> |
| 138 | * |
| 139 | * @param constraint the constraint used to filter the data |
| 140 | * @return the results of the filtering operation |
| 141 | * |
| 142 | * @see #filter(CharSequence, android.widget.Filter.FilterListener) |
| 143 | * @see #publishResults(CharSequence, android.widget.Filter.FilterResults) |
| 144 | * @see android.widget.Filter.FilterResults |
| 145 | */ |
| 146 | protected abstract FilterResults performFiltering(CharSequence constraint); |
| 147 | |
| 148 | /** |
| 149 | * <p>Invoked in the UI thread to publish the filtering results in the |
| 150 | * user interface. Subclasses must implement this method to display the |
| 151 | * results computed in {@link #performFiltering}.</p> |
| 152 | * |
| 153 | * @param constraint the constraint used to filter the data |
| 154 | * @param results the results of the filtering operation |
| 155 | * |
| 156 | * @see #filter(CharSequence, android.widget.Filter.FilterListener) |
| 157 | * @see #performFiltering(CharSequence) |
| 158 | * @see android.widget.Filter.FilterResults |
| 159 | */ |
| 160 | protected abstract void publishResults(CharSequence constraint, |
| 161 | FilterResults results); |
| 162 | |
| 163 | /** |
| 164 | * <p>Converts a value from the filtered set into a CharSequence. Subclasses |
| 165 | * should override this method to convert their results. The default |
| 166 | * implementation returns an empty String for null values or the default |
| 167 | * String representation of the value.</p> |
| 168 | * |
| 169 | * @param resultValue the value to convert to a CharSequence |
| 170 | * @return a CharSequence representing the value |
| 171 | */ |
| 172 | public CharSequence convertResultToString(Object resultValue) { |
| 173 | return resultValue == null ? "" : resultValue.toString(); |
| 174 | } |
| 175 | |
| 176 | /** |
| 177 | * <p>Holds the results of a filtering operation. The results are the values |
| 178 | * computed by the filtering operation and the number of these values.</p> |
| 179 | */ |
| 180 | protected static class FilterResults { |
| 181 | public FilterResults() { |
| 182 | // nothing to see here |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * <p>Contains all the values computed by the filtering operation.</p> |
| 187 | */ |
| 188 | public Object values; |
| 189 | |
| 190 | /** |
| 191 | * <p>Contains the number of values computed by the filtering |
| 192 | * operation.</p> |
| 193 | */ |
| 194 | public int count; |
| 195 | } |
| 196 | |
| 197 | /** |
| 198 | * <p>Listener used to receive a notification upon completion of a filtering |
| 199 | * operation.</p> |
| 200 | */ |
| 201 | public static interface FilterListener { |
| 202 | /** |
| 203 | * <p>Notifies the end of a filtering operation.</p> |
| 204 | * |
| 205 | * @param count the number of values computed by the filter |
| 206 | */ |
| 207 | public void onFilterComplete(int count); |
| 208 | } |
| 209 | |
| 210 | /** |
| 211 | * <p>Worker thread handler. When a new filtering request is posted from |
| 212 | * {@link android.widget.Filter#filter(CharSequence, android.widget.Filter.FilterListener)}, |
| 213 | * it is sent to this handler.</p> |
| 214 | */ |
| 215 | private class RequestHandler extends Handler { |
| 216 | public RequestHandler(Looper looper) { |
| 217 | super(looper); |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * <p>Handles filtering requests by calling |
| 222 | * {@link Filter#performFiltering} and then sending a message |
| 223 | * with the results to the results handler.</p> |
| 224 | * |
| 225 | * @param msg the filtering request |
| 226 | */ |
| 227 | public void handleMessage(Message msg) { |
| 228 | int what = msg.what; |
| 229 | Message message; |
| 230 | switch (what) { |
| 231 | case FILTER_TOKEN: |
| 232 | RequestArguments args = (RequestArguments) msg.obj; |
| 233 | try { |
| 234 | args.results = performFiltering(args.constraint); |
| 235 | } catch (Exception e) { |
| 236 | args.results = new FilterResults(); |
| 237 | Log.w(LOG_TAG, "An exception occured during performFiltering()!", e); |
| 238 | } finally { |
| 239 | message = mResultHandler.obtainMessage(what); |
| 240 | message.obj = args; |
| 241 | message.sendToTarget(); |
| 242 | } |
| 243 | |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 244 | synchronized (mLock) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 245 | if (mThreadHandler != null) { |
| 246 | Message finishMessage = mThreadHandler.obtainMessage(FINISH_TOKEN); |
| 247 | mThreadHandler.sendMessageDelayed(finishMessage, 3000); |
| 248 | } |
| 249 | } |
| 250 | break; |
| 251 | case FINISH_TOKEN: |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 252 | synchronized (mLock) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 253 | if (mThreadHandler != null) { |
| 254 | mThreadHandler.getLooper().quit(); |
| 255 | mThreadHandler = null; |
| 256 | } |
| 257 | } |
| 258 | break; |
| 259 | } |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | /** |
| 264 | * <p>Handles the results of a filtering operation. The results are |
| 265 | * handled in the UI thread.</p> |
| 266 | */ |
| 267 | private class ResultsHandler extends Handler { |
| 268 | /** |
| 269 | * <p>Messages received from the request handler are processed in the |
| 270 | * UI thread. The processing involves calling |
| 271 | * {@link Filter#publishResults(CharSequence, |
| 272 | * android.widget.Filter.FilterResults)} |
| 273 | * to post the results back in the UI and then notifying the listener, |
| 274 | * if any.</p> |
| 275 | * |
| 276 | * @param msg the filtering results |
| 277 | */ |
| 278 | @Override |
| 279 | public void handleMessage(Message msg) { |
| 280 | RequestArguments args = (RequestArguments) msg.obj; |
| 281 | |
| 282 | publishResults(args.constraint, args.results); |
| 283 | if (args.listener != null) { |
| 284 | int count = args.results != null ? args.results.count : -1; |
| 285 | args.listener.onFilterComplete(count); |
| 286 | } |
| 287 | } |
| 288 | } |
| 289 | |
| 290 | /** |
| 291 | * <p>Holds the arguments of a filtering request as well as the results |
| 292 | * of the request.</p> |
| 293 | */ |
| 294 | private static class RequestArguments { |
| 295 | /** |
| 296 | * <p>The constraint used to filter the data.</p> |
| 297 | */ |
| 298 | CharSequence constraint; |
| 299 | |
| 300 | /** |
| 301 | * <p>The listener to notify upon completion. Can be null.</p> |
| 302 | */ |
| 303 | FilterListener listener; |
| 304 | |
| 305 | /** |
| 306 | * <p>The results of the filtering operation.</p> |
| 307 | */ |
| 308 | FilterResults results; |
| 309 | } |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 310 | |
| 311 | /** |
| 312 | * @hide |
| 313 | */ |
| 314 | public interface Delayer { |
| 315 | |
| 316 | /** |
| 317 | * @param constraint The constraint passed to {@link Filter#filter(CharSequence)} |
| 318 | * @return The delay that should be used for |
| 319 | * {@link Handler#sendMessageDelayed(android.os.Message, long)} |
| 320 | */ |
| 321 | long getPostingDelay(CharSequence constraint); |
| 322 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 323 | } |