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 | |
Artur Satayev | ed5a6ae | 2019-12-10 17:47:54 +0000 | [diff] [blame] | 19 | import android.compat.annotation.UnsupportedAppUsage; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 20 | import android.os.Handler; |
| 21 | import android.os.HandlerThread; |
| 22 | import android.os.Looper; |
| 23 | import android.os.Message; |
| 24 | import android.util.Log; |
| 25 | |
| 26 | /** |
| 27 | * <p>A filter constrains data with a filtering pattern.</p> |
| 28 | * |
| 29 | * <p>Filters are usually created by {@link android.widget.Filterable} |
| 30 | * classes.</p> |
| 31 | * |
| 32 | * <p>Filtering operations performed by calling {@link #filter(CharSequence)} or |
| 33 | * {@link #filter(CharSequence, android.widget.Filter.FilterListener)} are |
| 34 | * performed asynchronously. When these methods are called, a filtering request |
| 35 | * is posted in a request queue and processed later. Any call to one of these |
| 36 | * methods will cancel any previous non-executed filtering request.</p> |
| 37 | * |
| 38 | * @see android.widget.Filterable |
| 39 | */ |
| 40 | public abstract class Filter { |
| 41 | private static final String LOG_TAG = "Filter"; |
| 42 | |
| 43 | private static final String THREAD_NAME = "Filter"; |
| 44 | private static final int FILTER_TOKEN = 0xD0D0F00D; |
| 45 | private static final int FINISH_TOKEN = 0xDEADBEEF; |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 46 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 47 | private Handler mThreadHandler; |
| 48 | private Handler mResultHandler; |
| 49 | |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 50 | private Delayer mDelayer; |
| 51 | |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 52 | private final Object mLock = new Object(); |
| 53 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 54 | /** |
| 55 | * <p>Creates a new asynchronous filter.</p> |
| 56 | */ |
| 57 | public Filter() { |
| 58 | mResultHandler = new ResultsHandler(); |
| 59 | } |
| 60 | |
| 61 | /** |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 62 | * Provide an interface that decides how long to delay the message for a given query. Useful |
| 63 | * for heuristics such as posting a delay for the delete key to avoid doing any work while the |
| 64 | * user holds down the delete key. |
| 65 | * |
| 66 | * @param delayer The delayer. |
| 67 | * @hide |
| 68 | */ |
Mathew Inwood | 978c6e2 | 2018-08-21 15:58:55 +0100 | [diff] [blame] | 69 | @UnsupportedAppUsage |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 70 | public void setDelayer(Delayer delayer) { |
| 71 | synchronized (mLock) { |
| 72 | mDelayer = delayer; |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | /** |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 77 | * <p>Starts an asynchronous filtering operation. Calling this method |
| 78 | * cancels all previous non-executed filtering requests and posts a new |
| 79 | * filtering request that will be executed later.</p> |
| 80 | * |
| 81 | * @param constraint the constraint used to filter the data |
| 82 | * |
| 83 | * @see #filter(CharSequence, android.widget.Filter.FilterListener) |
| 84 | */ |
| 85 | public final void filter(CharSequence constraint) { |
| 86 | filter(constraint, null); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * <p>Starts an asynchronous filtering operation. Calling this method |
| 91 | * cancels all previous non-executed filtering requests and posts a new |
| 92 | * filtering request that will be executed later.</p> |
| 93 | * |
| 94 | * <p>Upon completion, the listener is notified.</p> |
| 95 | * |
| 96 | * @param constraint the constraint used to filter the data |
| 97 | * @param listener a listener notified upon completion of the operation |
| 98 | * |
| 99 | * @see #filter(CharSequence) |
| 100 | * @see #performFiltering(CharSequence) |
| 101 | * @see #publishResults(CharSequence, android.widget.Filter.FilterResults) |
| 102 | */ |
| 103 | public final void filter(CharSequence constraint, FilterListener listener) { |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 104 | synchronized (mLock) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 105 | if (mThreadHandler == null) { |
Karl Rosaen | ab3ef10 | 2009-07-15 10:09:56 -0700 | [diff] [blame] | 106 | HandlerThread thread = new HandlerThread( |
| 107 | THREAD_NAME, android.os.Process.THREAD_PRIORITY_BACKGROUND); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 108 | thread.start(); |
| 109 | mThreadHandler = new RequestHandler(thread.getLooper()); |
| 110 | } |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 111 | |
| 112 | final long delay = (mDelayer == null) ? 0 : mDelayer.getPostingDelay(constraint); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 113 | |
| 114 | Message message = mThreadHandler.obtainMessage(FILTER_TOKEN); |
| 115 | |
| 116 | RequestArguments args = new RequestArguments(); |
| 117 | // make sure we use an immutable copy of the constraint, so that |
| 118 | // it doesn't change while the filter operation is in progress |
| 119 | args.constraint = constraint != null ? constraint.toString() : null; |
| 120 | args.listener = listener; |
| 121 | message.obj = args; |
| 122 | |
| 123 | mThreadHandler.removeMessages(FILTER_TOKEN); |
| 124 | mThreadHandler.removeMessages(FINISH_TOKEN); |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 125 | mThreadHandler.sendMessageDelayed(message, delay); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 126 | } |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | * <p>Invoked in a worker thread to filter the data according to the |
| 131 | * constraint. Subclasses must implement this method to perform the |
| 132 | * filtering operation. Results computed by the filtering operation |
| 133 | * must be returned as a {@link android.widget.Filter.FilterResults} that |
| 134 | * will then be published in the UI thread through |
| 135 | * {@link #publishResults(CharSequence, |
| 136 | * android.widget.Filter.FilterResults)}.</p> |
| 137 | * |
| 138 | * <p><strong>Contract:</strong> When the constraint is null, the original |
| 139 | * data must be restored.</p> |
| 140 | * |
| 141 | * @param constraint the constraint used to filter the data |
| 142 | * @return the results of the filtering operation |
| 143 | * |
| 144 | * @see #filter(CharSequence, android.widget.Filter.FilterListener) |
| 145 | * @see #publishResults(CharSequence, android.widget.Filter.FilterResults) |
| 146 | * @see android.widget.Filter.FilterResults |
| 147 | */ |
| 148 | protected abstract FilterResults performFiltering(CharSequence constraint); |
| 149 | |
| 150 | /** |
| 151 | * <p>Invoked in the UI thread to publish the filtering results in the |
| 152 | * user interface. Subclasses must implement this method to display the |
| 153 | * results computed in {@link #performFiltering}.</p> |
| 154 | * |
| 155 | * @param constraint the constraint used to filter the data |
| 156 | * @param results the results of the filtering operation |
| 157 | * |
| 158 | * @see #filter(CharSequence, android.widget.Filter.FilterListener) |
| 159 | * @see #performFiltering(CharSequence) |
| 160 | * @see android.widget.Filter.FilterResults |
| 161 | */ |
| 162 | protected abstract void publishResults(CharSequence constraint, |
| 163 | FilterResults results); |
| 164 | |
| 165 | /** |
| 166 | * <p>Converts a value from the filtered set into a CharSequence. Subclasses |
| 167 | * should override this method to convert their results. The default |
| 168 | * implementation returns an empty String for null values or the default |
| 169 | * String representation of the value.</p> |
| 170 | * |
| 171 | * @param resultValue the value to convert to a CharSequence |
| 172 | * @return a CharSequence representing the value |
| 173 | */ |
| 174 | public CharSequence convertResultToString(Object resultValue) { |
| 175 | return resultValue == null ? "" : resultValue.toString(); |
| 176 | } |
| 177 | |
| 178 | /** |
| 179 | * <p>Holds the results of a filtering operation. The results are the values |
| 180 | * computed by the filtering operation and the number of these values.</p> |
| 181 | */ |
| 182 | protected static class FilterResults { |
| 183 | public FilterResults() { |
| 184 | // nothing to see here |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * <p>Contains all the values computed by the filtering operation.</p> |
| 189 | */ |
| 190 | public Object values; |
| 191 | |
| 192 | /** |
| 193 | * <p>Contains the number of values computed by the filtering |
| 194 | * operation.</p> |
| 195 | */ |
| 196 | public int count; |
| 197 | } |
| 198 | |
| 199 | /** |
| 200 | * <p>Listener used to receive a notification upon completion of a filtering |
| 201 | * operation.</p> |
| 202 | */ |
| 203 | public static interface FilterListener { |
| 204 | /** |
| 205 | * <p>Notifies the end of a filtering operation.</p> |
| 206 | * |
| 207 | * @param count the number of values computed by the filter |
| 208 | */ |
| 209 | public void onFilterComplete(int count); |
| 210 | } |
| 211 | |
| 212 | /** |
| 213 | * <p>Worker thread handler. When a new filtering request is posted from |
| 214 | * {@link android.widget.Filter#filter(CharSequence, android.widget.Filter.FilterListener)}, |
| 215 | * it is sent to this handler.</p> |
| 216 | */ |
| 217 | private class RequestHandler extends Handler { |
| 218 | public RequestHandler(Looper looper) { |
| 219 | super(looper); |
| 220 | } |
| 221 | |
| 222 | /** |
| 223 | * <p>Handles filtering requests by calling |
| 224 | * {@link Filter#performFiltering} and then sending a message |
| 225 | * with the results to the results handler.</p> |
| 226 | * |
| 227 | * @param msg the filtering request |
| 228 | */ |
| 229 | public void handleMessage(Message msg) { |
| 230 | int what = msg.what; |
| 231 | Message message; |
| 232 | switch (what) { |
| 233 | case FILTER_TOKEN: |
| 234 | RequestArguments args = (RequestArguments) msg.obj; |
| 235 | try { |
| 236 | args.results = performFiltering(args.constraint); |
| 237 | } catch (Exception e) { |
| 238 | args.results = new FilterResults(); |
| 239 | Log.w(LOG_TAG, "An exception occured during performFiltering()!", e); |
| 240 | } finally { |
| 241 | message = mResultHandler.obtainMessage(what); |
| 242 | message.obj = args; |
| 243 | message.sendToTarget(); |
| 244 | } |
| 245 | |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 246 | synchronized (mLock) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 247 | if (mThreadHandler != null) { |
| 248 | Message finishMessage = mThreadHandler.obtainMessage(FINISH_TOKEN); |
| 249 | mThreadHandler.sendMessageDelayed(finishMessage, 3000); |
| 250 | } |
| 251 | } |
| 252 | break; |
| 253 | case FINISH_TOKEN: |
The Android Open Source Project | b2a3dd8 | 2009-03-09 11:52:12 -0700 | [diff] [blame] | 254 | synchronized (mLock) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 255 | if (mThreadHandler != null) { |
| 256 | mThreadHandler.getLooper().quit(); |
| 257 | mThreadHandler = null; |
| 258 | } |
| 259 | } |
| 260 | break; |
| 261 | } |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | /** |
| 266 | * <p>Handles the results of a filtering operation. The results are |
| 267 | * handled in the UI thread.</p> |
| 268 | */ |
| 269 | private class ResultsHandler extends Handler { |
| 270 | /** |
| 271 | * <p>Messages received from the request handler are processed in the |
| 272 | * UI thread. The processing involves calling |
| 273 | * {@link Filter#publishResults(CharSequence, |
| 274 | * android.widget.Filter.FilterResults)} |
| 275 | * to post the results back in the UI and then notifying the listener, |
| 276 | * if any.</p> |
| 277 | * |
| 278 | * @param msg the filtering results |
| 279 | */ |
| 280 | @Override |
| 281 | public void handleMessage(Message msg) { |
| 282 | RequestArguments args = (RequestArguments) msg.obj; |
| 283 | |
| 284 | publishResults(args.constraint, args.results); |
| 285 | if (args.listener != null) { |
| 286 | int count = args.results != null ? args.results.count : -1; |
| 287 | args.listener.onFilterComplete(count); |
| 288 | } |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | /** |
| 293 | * <p>Holds the arguments of a filtering request as well as the results |
| 294 | * of the request.</p> |
| 295 | */ |
| 296 | private static class RequestArguments { |
| 297 | /** |
| 298 | * <p>The constraint used to filter the data.</p> |
| 299 | */ |
| 300 | CharSequence constraint; |
| 301 | |
| 302 | /** |
| 303 | * <p>The listener to notify upon completion. Can be null.</p> |
| 304 | */ |
| 305 | FilterListener listener; |
| 306 | |
| 307 | /** |
| 308 | * <p>The results of the filtering operation.</p> |
| 309 | */ |
| 310 | FilterResults results; |
| 311 | } |
Karl Rosaen | 8bf92e0 | 2009-07-16 11:57:59 -0700 | [diff] [blame] | 312 | |
| 313 | /** |
| 314 | * @hide |
| 315 | */ |
| 316 | public interface Delayer { |
| 317 | |
| 318 | /** |
| 319 | * @param constraint The constraint passed to {@link Filter#filter(CharSequence)} |
| 320 | * @return The delay that should be used for |
| 321 | * {@link Handler#sendMessageDelayed(android.os.Message, long)} |
| 322 | */ |
| 323 | long getPostingDelay(CharSequence constraint); |
| 324 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 325 | } |