| 1 | /* |
| 2 | * Copyright (C) 2011 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.support.v2.widget; |
| 18 | |
| 19 | import android.content.Context; |
| 20 | import android.database.ContentObserver; |
| 21 | import android.database.Cursor; |
| 22 | import android.database.DataSetObserver; |
| 23 | import android.os.Handler; |
| 24 | import android.util.Config; |
| 25 | import android.util.Log; |
| 26 | import android.view.View; |
| 27 | import android.view.ViewGroup; |
| 28 | import android.widget.BaseAdapter; |
| 29 | import android.widget.Filter; |
| 30 | import android.widget.FilterQueryProvider; |
| 31 | import android.widget.Filterable; |
| 32 | |
| 33 | /** |
| 34 | * Static library support version of the framework's {@link android.widget.CursorAdapter}. |
| 35 | * Used to write apps that run on platforms prior to Android 3.0. When running |
| 36 | * on Android 3.0 or above, this implementation is still used; it does not try |
| 37 | * to switch to the framework's implementation. See the framework SDK |
| 38 | * documentation for a class overview. |
| 39 | */ |
| 40 | public abstract class CursorAdapter extends BaseAdapter implements Filterable, |
| 41 | CursorFilter.CursorFilterClient { |
| 42 | /** |
| 43 | * This field should be made private, so it is hidden from the SDK. |
| 44 | * {@hide} |
| 45 | */ |
| 46 | protected boolean mDataValid; |
| 47 | /** |
| 48 | * This field should be made private, so it is hidden from the SDK. |
| 49 | * {@hide} |
| 50 | */ |
| 51 | protected boolean mAutoRequery; |
| 52 | /** |
| 53 | * This field should be made private, so it is hidden from the SDK. |
| 54 | * {@hide} |
| 55 | */ |
| 56 | protected Cursor mCursor; |
| 57 | /** |
| 58 | * This field should be made private, so it is hidden from the SDK. |
| 59 | * {@hide} |
| 60 | */ |
| 61 | protected Context mContext; |
| 62 | /** |
| 63 | * This field should be made private, so it is hidden from the SDK. |
| 64 | * {@hide} |
| 65 | */ |
| 66 | protected int mRowIDColumn; |
| 67 | /** |
| 68 | * This field should be made private, so it is hidden from the SDK. |
| 69 | * {@hide} |
| 70 | */ |
| 71 | protected ChangeObserver mChangeObserver; |
| 72 | /** |
| 73 | * This field should be made private, so it is hidden from the SDK. |
| 74 | * {@hide} |
| 75 | */ |
| 76 | protected DataSetObserver mDataSetObserver; |
| 77 | /** |
| 78 | * This field should be made private, so it is hidden from the SDK. |
| 79 | * {@hide} |
| 80 | */ |
| 81 | protected CursorFilter mCursorFilter; |
| 82 | /** |
| 83 | * This field should be made private, so it is hidden from the SDK. |
| 84 | * {@hide} |
| 85 | */ |
| 86 | protected FilterQueryProvider mFilterQueryProvider; |
| 87 | |
| 88 | /** |
| 89 | * If set the adapter will call requery() on the cursor whenever a content change |
| 90 | * notification is delivered. Implies {@link #FLAG_REGISTER_CONTENT_OBSERVER}. |
| 91 | * |
| 92 | * @deprecated This option is discouraged, as it results in Cursor queries |
| 93 | * being performed on the application's UI thread and thus can cause poor |
| 94 | * responsiveness or even Application Not Responding errors. As an alternative, |
| 95 | * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}. |
| 96 | */ |
| 97 | @Deprecated |
| 98 | public static final int FLAG_AUTO_REQUERY = 0x01; |
| 99 | |
| 100 | /** |
| 101 | * If set the adapter will register a content observer on the cursor and will call |
| 102 | * {@link #onContentChanged()} when a notification comes in. Be careful when |
| 103 | * using this flag: you will need to unset the current Cursor from the adapter |
| 104 | * to avoid leaks due to its registered observers. This flag is not needed |
| 105 | * when using a CursorAdapter with a |
| 106 | * {@link android.content.CursorLoader}. |
| 107 | */ |
| 108 | public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02; |
| 109 | |
| 110 | /** |
| 111 | * Constructor that always enables auto-requery. |
| 112 | * |
| 113 | * @deprecated This option is discouraged, as it results in Cursor queries |
| 114 | * being performed on the application's UI thread and thus can cause poor |
| 115 | * responsiveness or even Application Not Responding errors. As an alternative, |
| 116 | * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}. |
| 117 | * |
| 118 | * @param c The cursor from which to get the data. |
| 119 | * @param context The context |
| 120 | */ |
| 121 | @Deprecated |
| 122 | public CursorAdapter(Context context, Cursor c) { |
| 123 | init(context, c, FLAG_AUTO_REQUERY); |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * Constructor that allows control over auto-requery. It is recommended |
| 128 | * you not use this, but instead {@link #CursorAdapter(Context, Cursor, int)}. |
| 129 | * When using this constructor, {@link #FLAG_REGISTER_CONTENT_OBSERVER} |
| 130 | * will always be set. |
| 131 | * |
| 132 | * @param c The cursor from which to get the data. |
| 133 | * @param context The context |
| 134 | * @param autoRequery If true the adapter will call requery() on the |
| 135 | * cursor whenever it changes so the most recent |
| 136 | * data is always displayed. Using true here is discouraged. |
| 137 | */ |
| 138 | public CursorAdapter(Context context, Cursor c, boolean autoRequery) { |
| 139 | init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER); |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * Recommended constructor. |
| 144 | * |
| 145 | * @param c The cursor from which to get the data. |
| 146 | * @param context The context |
| 147 | * @param flags Flags used to determine the behavior of the adapter; may |
| 148 | * be any combination of {@link #FLAG_AUTO_REQUERY} and |
| 149 | * {@link #FLAG_REGISTER_CONTENT_OBSERVER}. |
| 150 | */ |
| 151 | public CursorAdapter(Context context, Cursor c, int flags) { |
| 152 | init(context, c, flags); |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * @deprecated Don't use this, use the normal constructor. This will |
| 157 | * be removed in the future. |
| 158 | */ |
| 159 | @Deprecated |
| 160 | protected void init(Context context, Cursor c, boolean autoRequery) { |
| 161 | init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER); |
| 162 | } |
| 163 | |
| 164 | void init(Context context, Cursor c, int flags) { |
| 165 | if ((flags & FLAG_AUTO_REQUERY) == FLAG_AUTO_REQUERY) { |
| 166 | flags |= FLAG_REGISTER_CONTENT_OBSERVER; |
| 167 | mAutoRequery = true; |
| 168 | } else { |
| 169 | mAutoRequery = false; |
| 170 | } |
| 171 | boolean cursorPresent = c != null; |
| 172 | mCursor = c; |
| 173 | mDataValid = cursorPresent; |
| 174 | mContext = context; |
| 175 | mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; |
| 176 | if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) { |
| 177 | mChangeObserver = new ChangeObserver(); |
| 178 | mDataSetObserver = new MyDataSetObserver(); |
| 179 | } else { |
| 180 | mChangeObserver = null; |
| 181 | mDataSetObserver = null; |
| 182 | } |
| 183 | |
| 184 | if (cursorPresent) { |
| 185 | if (mChangeObserver != null) c.registerContentObserver(mChangeObserver); |
| 186 | if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver); |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | /** |
| 191 | * Returns the cursor. |
| 192 | * @return the cursor. |
| 193 | */ |
| 194 | public Cursor getCursor() { |
| 195 | return mCursor; |
| 196 | } |
| 197 | |
| 198 | /** |
| 199 | * @see android.widget.ListAdapter#getCount() |
| 200 | */ |
| 201 | public int getCount() { |
| 202 | if (mDataValid && mCursor != null) { |
| 203 | return mCursor.getCount(); |
| 204 | } else { |
| 205 | return 0; |
| 206 | } |
| 207 | } |
| 208 | |
| 209 | /** |
| 210 | * @see android.widget.ListAdapter#getItem(int) |
| 211 | */ |
| 212 | public Object getItem(int position) { |
| 213 | if (mDataValid && mCursor != null) { |
| 214 | mCursor.moveToPosition(position); |
| 215 | return mCursor; |
| 216 | } else { |
| 217 | return null; |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * @see android.widget.ListAdapter#getItemId(int) |
| 223 | */ |
| 224 | public long getItemId(int position) { |
| 225 | if (mDataValid && mCursor != null) { |
| 226 | if (mCursor.moveToPosition(position)) { |
| 227 | return mCursor.getLong(mRowIDColumn); |
| 228 | } else { |
| 229 | return 0; |
| 230 | } |
| 231 | } else { |
| 232 | return 0; |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | @Override |
| 237 | public boolean hasStableIds() { |
| 238 | return true; |
| 239 | } |
| 240 | |
| 241 | /** |
| 242 | * @see android.widget.ListAdapter#getView(int, View, ViewGroup) |
| 243 | */ |
| 244 | public View getView(int position, View convertView, ViewGroup parent) { |
| 245 | if (!mDataValid) { |
| 246 | throw new IllegalStateException("this should only be called when the cursor is valid"); |
| 247 | } |
| 248 | if (!mCursor.moveToPosition(position)) { |
| 249 | throw new IllegalStateException("couldn't move cursor to position " + position); |
| 250 | } |
| 251 | View v; |
| 252 | if (convertView == null) { |
| 253 | v = newView(mContext, mCursor, parent); |
| 254 | } else { |
| 255 | v = convertView; |
| 256 | } |
| 257 | bindView(v, mContext, mCursor); |
| 258 | return v; |
| 259 | } |
| 260 | |
| 261 | @Override |
| 262 | public View getDropDownView(int position, View convertView, ViewGroup parent) { |
| 263 | if (mDataValid) { |
| 264 | mCursor.moveToPosition(position); |
| 265 | View v; |
| 266 | if (convertView == null) { |
| 267 | v = newDropDownView(mContext, mCursor, parent); |
| 268 | } else { |
| 269 | v = convertView; |
| 270 | } |
| 271 | bindView(v, mContext, mCursor); |
| 272 | return v; |
| 273 | } else { |
| 274 | return null; |
| 275 | } |
| 276 | } |
| 277 | |
| 278 | /** |
| 279 | * Makes a new view to hold the data pointed to by cursor. |
| 280 | * @param context Interface to application's global information |
| 281 | * @param cursor The cursor from which to get the data. The cursor is already |
| 282 | * moved to the correct position. |
| 283 | * @param parent The parent to which the new view is attached to |
| 284 | * @return the newly created view. |
| 285 | */ |
| 286 | public abstract View newView(Context context, Cursor cursor, ViewGroup parent); |
| 287 | |
| 288 | /** |
| 289 | * Makes a new drop down view to hold the data pointed to by cursor. |
| 290 | * @param context Interface to application's global information |
| 291 | * @param cursor The cursor from which to get the data. The cursor is already |
| 292 | * moved to the correct position. |
| 293 | * @param parent The parent to which the new view is attached to |
| 294 | * @return the newly created view. |
| 295 | */ |
| 296 | public View newDropDownView(Context context, Cursor cursor, ViewGroup parent) { |
| 297 | return newView(context, cursor, parent); |
| 298 | } |
| 299 | |
| 300 | /** |
| 301 | * Bind an existing view to the data pointed to by cursor |
| 302 | * @param view Existing view, returned earlier by newView |
| 303 | * @param context Interface to application's global information |
| 304 | * @param cursor The cursor from which to get the data. The cursor is already |
| 305 | * moved to the correct position. |
| 306 | */ |
| 307 | public abstract void bindView(View view, Context context, Cursor cursor); |
| 308 | |
| 309 | /** |
| 310 | * Change the underlying cursor to a new cursor. If there is an existing cursor it will be |
| 311 | * closed. |
| 312 | * |
| 313 | * @param cursor The new cursor to be used |
| 314 | */ |
| 315 | public void changeCursor(Cursor cursor) { |
| 316 | Cursor old = swapCursor(cursor); |
| 317 | if (old != null) { |
| 318 | old.close(); |
| 319 | } |
| 320 | } |
| 321 | |
| 322 | /** |
| 323 | * Swap in a new Cursor, returning the old Cursor. Unlike |
| 324 | * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em> |
| 325 | * closed. |
| 326 | * |
| 327 | * @param newCursor The new cursor to be used. |
| 328 | * @return Returns the previously set Cursor, or null if there wasa not one. |
| 329 | * If the given new Cursor is the same instance is the previously set |
| 330 | * Cursor, null is also returned. |
| 331 | */ |
| 332 | public Cursor swapCursor(Cursor newCursor) { |
| 333 | if (newCursor == mCursor) { |
| 334 | return null; |
| 335 | } |
| 336 | Cursor oldCursor = mCursor; |
| 337 | if (oldCursor != null) { |
| 338 | if (mChangeObserver != null) oldCursor.unregisterContentObserver(mChangeObserver); |
| 339 | if (mDataSetObserver != null) oldCursor.unregisterDataSetObserver(mDataSetObserver); |
| 340 | } |
| 341 | mCursor = newCursor; |
| 342 | if (newCursor != null) { |
| 343 | if (mChangeObserver != null) newCursor.registerContentObserver(mChangeObserver); |
| 344 | if (mDataSetObserver != null) newCursor.registerDataSetObserver(mDataSetObserver); |
| 345 | mRowIDColumn = newCursor.getColumnIndexOrThrow("_id"); |
| 346 | mDataValid = true; |
| 347 | // notify the observers about the new cursor |
| 348 | notifyDataSetChanged(); |
| 349 | } else { |
| 350 | mRowIDColumn = -1; |
| 351 | mDataValid = false; |
| 352 | // notify the observers about the lack of a data set |
| 353 | notifyDataSetInvalidated(); |
| 354 | } |
| 355 | return oldCursor; |
| 356 | } |
| 357 | |
| 358 | /** |
| 359 | * <p>Converts the cursor into a CharSequence. Subclasses should override this |
| 360 | * method to convert their results. The default implementation returns an |
| 361 | * empty String for null values or the default String representation of |
| 362 | * the value.</p> |
| 363 | * |
| 364 | * @param cursor the cursor to convert to a CharSequence |
| 365 | * @return a CharSequence representing the value |
| 366 | */ |
| 367 | public CharSequence convertToString(Cursor cursor) { |
| 368 | return cursor == null ? "" : cursor.toString(); |
| 369 | } |
| 370 | |
| 371 | /** |
| 372 | * Runs a query with the specified constraint. This query is requested |
| 373 | * by the filter attached to this adapter. |
| 374 | * |
| 375 | * The query is provided by a |
| 376 | * {@link android.widget.FilterQueryProvider}. |
| 377 | * If no provider is specified, the current cursor is not filtered and returned. |
| 378 | * |
| 379 | * After this method returns the resulting cursor is passed to {@link #changeCursor(Cursor)} |
| 380 | * and the previous cursor is closed. |
| 381 | * |
| 382 | * This method is always executed on a background thread, not on the |
| 383 | * application's main thread (or UI thread.) |
| 384 | * |
| 385 | * Contract: when constraint is null or empty, the original results, |
| 386 | * prior to any filtering, must be returned. |
| 387 | * |
| 388 | * @param constraint the constraint with which the query must be filtered |
| 389 | * |
| 390 | * @return a Cursor representing the results of the new query |
| 391 | * |
| 392 | * @see #getFilter() |
| 393 | * @see #getFilterQueryProvider() |
| 394 | * @see #setFilterQueryProvider(android.widget.FilterQueryProvider) |
| 395 | */ |
| 396 | public Cursor runQueryOnBackgroundThread(CharSequence constraint) { |
| 397 | if (mFilterQueryProvider != null) { |
| 398 | return mFilterQueryProvider.runQuery(constraint); |
| 399 | } |
| 400 | |
| 401 | return mCursor; |
| 402 | } |
| 403 | |
| 404 | public Filter getFilter() { |
| 405 | if (mCursorFilter == null) { |
| 406 | mCursorFilter = new CursorFilter(this); |
| 407 | } |
| 408 | return mCursorFilter; |
| 409 | } |
| 410 | |
| 411 | /** |
| 412 | * Returns the query filter provider used for filtering. When the |
| 413 | * provider is null, no filtering occurs. |
| 414 | * |
| 415 | * @return the current filter query provider or null if it does not exist |
| 416 | * |
| 417 | * @see #setFilterQueryProvider(android.widget.FilterQueryProvider) |
| 418 | * @see #runQueryOnBackgroundThread(CharSequence) |
| 419 | */ |
| 420 | public FilterQueryProvider getFilterQueryProvider() { |
| 421 | return mFilterQueryProvider; |
| 422 | } |
| 423 | |
| 424 | /** |
| 425 | * Sets the query filter provider used to filter the current Cursor. |
| 426 | * The provider's |
| 427 | * {@link android.widget.FilterQueryProvider#runQuery(CharSequence)} |
| 428 | * method is invoked when filtering is requested by a client of |
| 429 | * this adapter. |
| 430 | * |
| 431 | * @param filterQueryProvider the filter query provider or null to remove it |
| 432 | * |
| 433 | * @see #getFilterQueryProvider() |
| 434 | * @see #runQueryOnBackgroundThread(CharSequence) |
| 435 | */ |
| 436 | public void setFilterQueryProvider(FilterQueryProvider filterQueryProvider) { |
| 437 | mFilterQueryProvider = filterQueryProvider; |
| 438 | } |
| 439 | |
| 440 | /** |
| 441 | * Called when the {@link ContentObserver} on the cursor receives a change notification. |
| 442 | * The default implementation provides the auto-requery logic, but may be overridden by |
| 443 | * sub classes. |
| 444 | * |
| 445 | * @see ContentObserver#onChange(boolean) |
| 446 | */ |
| 447 | protected void onContentChanged() { |
| 448 | if (mAutoRequery && mCursor != null && !mCursor.isClosed()) { |
| 449 | if (Config.LOGV) Log.v("Cursor", "Auto requerying " + mCursor + " due to update"); |
| 450 | mDataValid = mCursor.requery(); |
| 451 | } |
| 452 | } |
| 453 | |
| 454 | private class ChangeObserver extends ContentObserver { |
| 455 | public ChangeObserver() { |
| 456 | super(new Handler()); |
| 457 | } |
| 458 | |
| 459 | @Override |
| 460 | public boolean deliverSelfNotifications() { |
| 461 | return true; |
| 462 | } |
| 463 | |
| 464 | @Override |
| 465 | public void onChange(boolean selfChange) { |
| 466 | onContentChanged(); |
| 467 | } |
| 468 | } |
| 469 | |
| 470 | private class MyDataSetObserver extends DataSetObserver { |
| 471 | @Override |
| 472 | public void onChanged() { |
| 473 | mDataValid = true; |
| 474 | notifyDataSetChanged(); |
| 475 | } |
| 476 | |
| 477 | @Override |
| 478 | public void onInvalidated() { |
| 479 | mDataValid = false; |
| 480 | notifyDataSetInvalidated(); |
| 481 | } |
| 482 | } |
| 483 | |
| 484 | } |