AdapterView.java revision b84b94e1a04cd1f396dd6fef98d65ca1a2729c92
1/* 2 * Copyright (C) 2006 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 17package android.widget; 18 19import android.content.Context; 20import android.database.DataSetObserver; 21import android.os.Parcelable; 22import android.os.SystemClock; 23import android.util.AttributeSet; 24import android.util.SparseArray; 25import android.view.ContextMenu; 26import android.view.ContextMenu.ContextMenuInfo; 27import android.view.SoundEffectConstants; 28import android.view.View; 29import android.view.ViewDebug; 30import android.view.ViewGroup; 31import android.view.accessibility.AccessibilityEvent; 32 33 34/** 35 * An AdapterView is a view whose children are determined by an {@link Adapter}. 36 * 37 * <p> 38 * See {@link ListView}, {@link GridView}, {@link Spinner} and 39 * {@link Gallery} for commonly used subclasses of AdapterView. 40 */ 41public abstract class AdapterView<T extends Adapter> extends ViewGroup { 42 43 /** 44 * The item view type returned by {@link Adapter#getItemViewType(int)} when 45 * the adapter does not want the item's view recycled. 46 */ 47 public static final int ITEM_VIEW_TYPE_IGNORE = -1; 48 49 /** 50 * The item view type returned by {@link Adapter#getItemViewType(int)} when 51 * the item is a header or footer. 52 */ 53 public static final int ITEM_VIEW_TYPE_HEADER_OR_FOOTER = -2; 54 55 /** 56 * The position of the first child displayed 57 */ 58 @ViewDebug.ExportedProperty(category = "scrolling") 59 int mFirstPosition = 0; 60 61 /** 62 * The offset in pixels from the top of the AdapterView to the top 63 * of the view to select during the next layout. 64 */ 65 int mSpecificTop; 66 67 /** 68 * Position from which to start looking for mSyncRowId 69 */ 70 int mSyncPosition; 71 72 /** 73 * Row id to look for when data has changed 74 */ 75 long mSyncRowId = INVALID_ROW_ID; 76 77 /** 78 * Height of the view when mSyncPosition and mSyncRowId where set 79 */ 80 long mSyncHeight; 81 82 /** 83 * True if we need to sync to mSyncRowId 84 */ 85 boolean mNeedSync = false; 86 87 /** 88 * Indicates whether to sync based on the selection or position. Possible 89 * values are {@link #SYNC_SELECTED_POSITION} or 90 * {@link #SYNC_FIRST_POSITION}. 91 */ 92 int mSyncMode; 93 94 /** 95 * Our height after the last layout 96 */ 97 private int mLayoutHeight; 98 99 /** 100 * Sync based on the selected child 101 */ 102 static final int SYNC_SELECTED_POSITION = 0; 103 104 /** 105 * Sync based on the first child displayed 106 */ 107 static final int SYNC_FIRST_POSITION = 1; 108 109 /** 110 * Maximum amount of time to spend in {@link #findSyncPosition()} 111 */ 112 static final int SYNC_MAX_DURATION_MILLIS = 100; 113 114 /** 115 * Indicates that this view is currently being laid out. 116 */ 117 boolean mInLayout = false; 118 119 /** 120 * The listener that receives notifications when an item is selected. 121 */ 122 OnItemSelectedListener mOnItemSelectedListener; 123 124 /** 125 * The listener that receives notifications when an item is clicked. 126 */ 127 OnItemClickListener mOnItemClickListener; 128 129 /** 130 * The listener that receives notifications when an item is long clicked. 131 */ 132 OnItemLongClickListener mOnItemLongClickListener; 133 134 /** 135 * True if the data has changed since the last layout 136 */ 137 boolean mDataChanged; 138 139 /** 140 * The position within the adapter's data set of the item to select 141 * during the next layout. 142 */ 143 @ViewDebug.ExportedProperty(category = "list") 144 int mNextSelectedPosition = INVALID_POSITION; 145 146 /** 147 * The item id of the item to select during the next layout. 148 */ 149 long mNextSelectedRowId = INVALID_ROW_ID; 150 151 /** 152 * The position within the adapter's data set of the currently selected item. 153 */ 154 @ViewDebug.ExportedProperty(category = "list") 155 int mSelectedPosition = INVALID_POSITION; 156 157 /** 158 * The item id of the currently selected item. 159 */ 160 long mSelectedRowId = INVALID_ROW_ID; 161 162 /** 163 * View to show if there are no items to show. 164 */ 165 private View mEmptyView; 166 167 /** 168 * The number of items in the current adapter. 169 */ 170 @ViewDebug.ExportedProperty(category = "list") 171 int mItemCount; 172 173 /** 174 * The number of items in the adapter before a data changed event occurred. 175 */ 176 int mOldItemCount; 177 178 /** 179 * Represents an invalid position. All valid positions are in the range 0 to 1 less than the 180 * number of items in the current adapter. 181 */ 182 public static final int INVALID_POSITION = -1; 183 184 /** 185 * Represents an empty or invalid row id 186 */ 187 public static final long INVALID_ROW_ID = Long.MIN_VALUE; 188 189 /** 190 * The last selected position we used when notifying 191 */ 192 int mOldSelectedPosition = INVALID_POSITION; 193 194 /** 195 * The id of the last selected position we used when notifying 196 */ 197 long mOldSelectedRowId = INVALID_ROW_ID; 198 199 /** 200 * Indicates what focusable state is requested when calling setFocusable(). 201 * In addition to this, this view has other criteria for actually 202 * determining the focusable state (such as whether its empty or the text 203 * filter is shown). 204 * 205 * @see #setFocusable(boolean) 206 * @see #checkFocus() 207 */ 208 private boolean mDesiredFocusableState; 209 private boolean mDesiredFocusableInTouchModeState; 210 211 private SelectionNotifier mSelectionNotifier; 212 /** 213 * When set to true, calls to requestLayout() will not propagate up the parent hierarchy. 214 * This is used to layout the children during a layout pass. 215 */ 216 boolean mBlockLayoutRequests = false; 217 218 public AdapterView(Context context) { 219 super(context); 220 } 221 222 public AdapterView(Context context, AttributeSet attrs) { 223 super(context, attrs); 224 } 225 226 public AdapterView(Context context, AttributeSet attrs, int defStyle) { 227 super(context, attrs, defStyle); 228 } 229 230 /** 231 * Interface definition for a callback to be invoked when an item in this 232 * AdapterView has been clicked. 233 */ 234 public interface OnItemClickListener { 235 236 /** 237 * Callback method to be invoked when an item in this AdapterView has 238 * been clicked. 239 * <p> 240 * Implementers can call getItemAtPosition(position) if they need 241 * to access the data associated with the selected item. 242 * 243 * @param parent The AdapterView where the click happened. 244 * @param view The view within the AdapterView that was clicked (this 245 * will be a view provided by the adapter) 246 * @param position The position of the view in the adapter. 247 * @param id The row id of the item that was clicked. 248 */ 249 void onItemClick(AdapterView<?> parent, View view, int position, long id); 250 } 251 252 /** 253 * Register a callback to be invoked when an item in this AdapterView has 254 * been clicked. 255 * 256 * @param listener The callback that will be invoked. 257 */ 258 public void setOnItemClickListener(OnItemClickListener listener) { 259 mOnItemClickListener = listener; 260 } 261 262 /** 263 * @return The callback to be invoked with an item in this AdapterView has 264 * been clicked, or null id no callback has been set. 265 */ 266 public final OnItemClickListener getOnItemClickListener() { 267 return mOnItemClickListener; 268 } 269 270 /** 271 * Call the OnItemClickListener, if it is defined. 272 * 273 * @param view The view within the AdapterView that was clicked. 274 * @param position The position of the view in the adapter. 275 * @param id The row id of the item that was clicked. 276 * @return True if there was an assigned OnItemClickListener that was 277 * called, false otherwise is returned. 278 */ 279 public boolean performItemClick(View view, int position, long id) { 280 if (mOnItemClickListener != null) { 281 playSoundEffect(SoundEffectConstants.CLICK); 282 if (view != null) { 283 view.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED); 284 } 285 mOnItemClickListener.onItemClick(this, view, position, id); 286 return true; 287 } 288 289 return false; 290 } 291 292 /** 293 * Interface definition for a callback to be invoked when an item in this 294 * view has been clicked and held. 295 */ 296 public interface OnItemLongClickListener { 297 /** 298 * Callback method to be invoked when an item in this view has been 299 * clicked and held. 300 * 301 * Implementers can call getItemAtPosition(position) if they need to access 302 * the data associated with the selected item. 303 * 304 * @param parent The AbsListView where the click happened 305 * @param view The view within the AbsListView that was clicked 306 * @param position The position of the view in the list 307 * @param id The row id of the item that was clicked 308 * 309 * @return true if the callback consumed the long click, false otherwise 310 */ 311 boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id); 312 } 313 314 315 /** 316 * Register a callback to be invoked when an item in this AdapterView has 317 * been clicked and held 318 * 319 * @param listener The callback that will run 320 */ 321 public void setOnItemLongClickListener(OnItemLongClickListener listener) { 322 if (!isLongClickable()) { 323 setLongClickable(true); 324 } 325 mOnItemLongClickListener = listener; 326 } 327 328 /** 329 * @return The callback to be invoked with an item in this AdapterView has 330 * been clicked and held, or null id no callback as been set. 331 */ 332 public final OnItemLongClickListener getOnItemLongClickListener() { 333 return mOnItemLongClickListener; 334 } 335 336 /** 337 * Interface definition for a callback to be invoked when 338 * an item in this view has been selected. 339 */ 340 public interface OnItemSelectedListener { 341 /** 342 * <p>Callback method to be invoked when an item in this view has been 343 * selected. This callback is invoked only when the newly selected 344 * position is different from the previously selected position or if 345 * there was no selected item.</p> 346 * 347 * Impelmenters can call getItemAtPosition(position) if they need to access the 348 * data associated with the selected item. 349 * 350 * @param parent The AdapterView where the selection happened 351 * @param view The view within the AdapterView that was clicked 352 * @param position The position of the view in the adapter 353 * @param id The row id of the item that is selected 354 */ 355 void onItemSelected(AdapterView<?> parent, View view, int position, long id); 356 357 /** 358 * Callback method to be invoked when the selection disappears from this 359 * view. The selection can disappear for instance when touch is activated 360 * or when the adapter becomes empty. 361 * 362 * @param parent The AdapterView that now contains no selected item. 363 */ 364 void onNothingSelected(AdapterView<?> parent); 365 } 366 367 368 /** 369 * Register a callback to be invoked when an item in this AdapterView has 370 * been selected. 371 * 372 * @param listener The callback that will run 373 */ 374 public void setOnItemSelectedListener(OnItemSelectedListener listener) { 375 mOnItemSelectedListener = listener; 376 } 377 378 public final OnItemSelectedListener getOnItemSelectedListener() { 379 return mOnItemSelectedListener; 380 } 381 382 /** 383 * Extra menu information provided to the 384 * {@link android.view.View.OnCreateContextMenuListener#onCreateContextMenu(ContextMenu, View, ContextMenuInfo) } 385 * callback when a context menu is brought up for this AdapterView. 386 * 387 */ 388 public static class AdapterContextMenuInfo implements ContextMenu.ContextMenuInfo { 389 390 public AdapterContextMenuInfo(View targetView, int position, long id) { 391 this.targetView = targetView; 392 this.position = position; 393 this.id = id; 394 } 395 396 /** 397 * The child view for which the context menu is being displayed. This 398 * will be one of the children of this AdapterView. 399 */ 400 public View targetView; 401 402 /** 403 * The position in the adapter for which the context menu is being 404 * displayed. 405 */ 406 public int position; 407 408 /** 409 * The row id of the item for which the context menu is being displayed. 410 */ 411 public long id; 412 } 413 414 /** 415 * Returns the adapter currently associated with this widget. 416 * 417 * @return The adapter used to provide this view's content. 418 */ 419 public abstract T getAdapter(); 420 421 /** 422 * Sets the adapter that provides the data and the views to represent the data 423 * in this widget. 424 * 425 * @param adapter The adapter to use to create this view's content. 426 */ 427 public abstract void setAdapter(T adapter); 428 429 /** 430 * This method is not supported and throws an UnsupportedOperationException when called. 431 * 432 * @param child Ignored. 433 * 434 * @throws UnsupportedOperationException Every time this method is invoked. 435 */ 436 @Override 437 public void addView(View child) { 438 throw new UnsupportedOperationException("addView(View) is not supported in AdapterView"); 439 } 440 441 /** 442 * This method is not supported and throws an UnsupportedOperationException when called. 443 * 444 * @param child Ignored. 445 * @param index Ignored. 446 * 447 * @throws UnsupportedOperationException Every time this method is invoked. 448 */ 449 @Override 450 public void addView(View child, int index) { 451 throw new UnsupportedOperationException("addView(View, int) is not supported in AdapterView"); 452 } 453 454 /** 455 * This method is not supported and throws an UnsupportedOperationException when called. 456 * 457 * @param child Ignored. 458 * @param params Ignored. 459 * 460 * @throws UnsupportedOperationException Every time this method is invoked. 461 */ 462 @Override 463 public void addView(View child, LayoutParams params) { 464 throw new UnsupportedOperationException("addView(View, LayoutParams) " 465 + "is not supported in AdapterView"); 466 } 467 468 /** 469 * This method is not supported and throws an UnsupportedOperationException when called. 470 * 471 * @param child Ignored. 472 * @param index Ignored. 473 * @param params Ignored. 474 * 475 * @throws UnsupportedOperationException Every time this method is invoked. 476 */ 477 @Override 478 public void addView(View child, int index, LayoutParams params) { 479 throw new UnsupportedOperationException("addView(View, int, LayoutParams) " 480 + "is not supported in AdapterView"); 481 } 482 483 /** 484 * This method is not supported and throws an UnsupportedOperationException when called. 485 * 486 * @param child Ignored. 487 * 488 * @throws UnsupportedOperationException Every time this method is invoked. 489 */ 490 @Override 491 public void removeView(View child) { 492 throw new UnsupportedOperationException("removeView(View) is not supported in AdapterView"); 493 } 494 495 /** 496 * This method is not supported and throws an UnsupportedOperationException when called. 497 * 498 * @param index Ignored. 499 * 500 * @throws UnsupportedOperationException Every time this method is invoked. 501 */ 502 @Override 503 public void removeViewAt(int index) { 504 throw new UnsupportedOperationException("removeViewAt(int) is not supported in AdapterView"); 505 } 506 507 /** 508 * This method is not supported and throws an UnsupportedOperationException when called. 509 * 510 * @throws UnsupportedOperationException Every time this method is invoked. 511 */ 512 @Override 513 public void removeAllViews() { 514 throw new UnsupportedOperationException("removeAllViews() is not supported in AdapterView"); 515 } 516 517 @Override 518 protected void onLayout(boolean changed, int left, int top, int right, int bottom) { 519 mLayoutHeight = getHeight(); 520 } 521 522 /** 523 * Return the position of the currently selected item within the adapter's data set 524 * 525 * @return int Position (starting at 0), or {@link #INVALID_POSITION} if there is nothing selected. 526 */ 527 @ViewDebug.CapturedViewProperty 528 public int getSelectedItemPosition() { 529 return mNextSelectedPosition; 530 } 531 532 /** 533 * @return The id corresponding to the currently selected item, or {@link #INVALID_ROW_ID} 534 * if nothing is selected. 535 */ 536 @ViewDebug.CapturedViewProperty 537 public long getSelectedItemId() { 538 return mNextSelectedRowId; 539 } 540 541 /** 542 * @return The view corresponding to the currently selected item, or null 543 * if nothing is selected 544 */ 545 public abstract View getSelectedView(); 546 547 /** 548 * @return The data corresponding to the currently selected item, or 549 * null if there is nothing selected. 550 */ 551 public Object getSelectedItem() { 552 T adapter = getAdapter(); 553 int selection = getSelectedItemPosition(); 554 if (adapter != null && adapter.getCount() > 0 && selection >= 0) { 555 return adapter.getItem(selection); 556 } else { 557 return null; 558 } 559 } 560 561 /** 562 * @return The number of items owned by the Adapter associated with this 563 * AdapterView. (This is the number of data items, which may be 564 * larger than the number of visible views.) 565 */ 566 @ViewDebug.CapturedViewProperty 567 public int getCount() { 568 return mItemCount; 569 } 570 571 /** 572 * Get the position within the adapter's data set for the view, where view is a an adapter item 573 * or a descendant of an adapter item. 574 * 575 * @param view an adapter item, or a descendant of an adapter item. This must be visible in this 576 * AdapterView at the time of the call. 577 * @return the position within the adapter's data set of the view, or {@link #INVALID_POSITION} 578 * if the view does not correspond to a list item (or it is not currently visible). 579 */ 580 public int getPositionForView(View view) { 581 View listItem = view; 582 try { 583 View v; 584 while (!(v = (View) listItem.getParent()).equals(this)) { 585 listItem = v; 586 } 587 } catch (ClassCastException e) { 588 // We made it up to the window without find this list view 589 return INVALID_POSITION; 590 } 591 592 // Search the children for the list item 593 final int childCount = getChildCount(); 594 for (int i = 0; i < childCount; i++) { 595 if (getChildAt(i).equals(listItem)) { 596 return mFirstPosition + i; 597 } 598 } 599 600 // Child not found! 601 return INVALID_POSITION; 602 } 603 604 /** 605 * Returns the position within the adapter's data set for the first item 606 * displayed on screen. 607 * 608 * @return The position within the adapter's data set 609 */ 610 public int getFirstVisiblePosition() { 611 return mFirstPosition; 612 } 613 614 /** 615 * Returns the position within the adapter's data set for the last item 616 * displayed on screen. 617 * 618 * @return The position within the adapter's data set 619 */ 620 public int getLastVisiblePosition() { 621 return mFirstPosition + getChildCount() - 1; 622 } 623 624 /** 625 * Sets the currently selected item. To support accessibility subclasses that 626 * override this method must invoke the overriden super method first. 627 * 628 * @param position Index (starting at 0) of the data item to be selected. 629 */ 630 public abstract void setSelection(int position); 631 632 /** 633 * Sets the view to show if the adapter is empty 634 */ 635 @android.view.RemotableViewMethod 636 public void setEmptyView(View emptyView) { 637 mEmptyView = emptyView; 638 639 final T adapter = getAdapter(); 640 final boolean empty = ((adapter == null) || adapter.isEmpty()); 641 updateEmptyStatus(empty); 642 } 643 644 /** 645 * When the current adapter is empty, the AdapterView can display a special view 646 * call the empty view. The empty view is used to provide feedback to the user 647 * that no data is available in this AdapterView. 648 * 649 * @return The view to show if the adapter is empty. 650 */ 651 public View getEmptyView() { 652 return mEmptyView; 653 } 654 655 /** 656 * Indicates whether this view is in filter mode. Filter mode can for instance 657 * be enabled by a user when typing on the keyboard. 658 * 659 * @return True if the view is in filter mode, false otherwise. 660 */ 661 boolean isInFilterMode() { 662 return false; 663 } 664 665 @Override 666 public void setFocusable(boolean focusable) { 667 final T adapter = getAdapter(); 668 final boolean empty = adapter == null || adapter.getCount() == 0; 669 670 mDesiredFocusableState = focusable; 671 if (!focusable) { 672 mDesiredFocusableInTouchModeState = false; 673 } 674 675 super.setFocusable(focusable && (!empty || isInFilterMode())); 676 } 677 678 @Override 679 public void setFocusableInTouchMode(boolean focusable) { 680 final T adapter = getAdapter(); 681 final boolean empty = adapter == null || adapter.getCount() == 0; 682 683 mDesiredFocusableInTouchModeState = focusable; 684 if (focusable) { 685 mDesiredFocusableState = true; 686 } 687 688 super.setFocusableInTouchMode(focusable && (!empty || isInFilterMode())); 689 } 690 691 void checkFocus() { 692 final T adapter = getAdapter(); 693 final boolean empty = adapter == null || adapter.getCount() == 0; 694 final boolean focusable = !empty || isInFilterMode(); 695 // The order in which we set focusable in touch mode/focusable may matter 696 // for the client, see View.setFocusableInTouchMode() comments for more 697 // details 698 super.setFocusableInTouchMode(focusable && mDesiredFocusableInTouchModeState); 699 super.setFocusable(focusable && mDesiredFocusableState); 700 if (mEmptyView != null) { 701 updateEmptyStatus((adapter == null) || adapter.isEmpty()); 702 } 703 } 704 705 /** 706 * Update the status of the list based on the empty parameter. If empty is true and 707 * we have an empty view, display it. In all the other cases, make sure that the listview 708 * is VISIBLE and that the empty view is GONE (if it's not null). 709 */ 710 private void updateEmptyStatus(boolean empty) { 711 if (isInFilterMode()) { 712 empty = false; 713 } 714 715 if (empty) { 716 if (mEmptyView != null) { 717 mEmptyView.setVisibility(View.VISIBLE); 718 setVisibility(View.GONE); 719 } else { 720 // If the caller just removed our empty view, make sure the list view is visible 721 setVisibility(View.VISIBLE); 722 } 723 724 // We are now GONE, so pending layouts will not be dispatched. 725 // Force one here to make sure that the state of the list matches 726 // the state of the adapter. 727 if (mDataChanged) { 728 this.onLayout(false, mLeft, mTop, mRight, mBottom); 729 } 730 } else { 731 if (mEmptyView != null) mEmptyView.setVisibility(View.GONE); 732 setVisibility(View.VISIBLE); 733 } 734 } 735 736 /** 737 * Gets the data associated with the specified position in the list. 738 * 739 * @param position Which data to get 740 * @return The data associated with the specified position in the list 741 */ 742 public Object getItemAtPosition(int position) { 743 T adapter = getAdapter(); 744 return (adapter == null || position < 0) ? null : adapter.getItem(position); 745 } 746 747 public long getItemIdAtPosition(int position) { 748 T adapter = getAdapter(); 749 return (adapter == null || position < 0) ? INVALID_ROW_ID : adapter.getItemId(position); 750 } 751 752 @Override 753 public void setOnClickListener(OnClickListener l) { 754 throw new RuntimeException("Don't call setOnClickListener for an AdapterView. " 755 + "You probably want setOnItemClickListener instead"); 756 } 757 758 /** 759 * Override to prevent freezing of any views created by the adapter. 760 */ 761 @Override 762 protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) { 763 dispatchFreezeSelfOnly(container); 764 } 765 766 /** 767 * Override to prevent thawing of any views created by the adapter. 768 */ 769 @Override 770 protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) { 771 dispatchThawSelfOnly(container); 772 } 773 774 class AdapterDataSetObserver extends DataSetObserver { 775 776 private Parcelable mInstanceState = null; 777 778 @Override 779 public void onChanged() { 780 mDataChanged = true; 781 mOldItemCount = mItemCount; 782 mItemCount = getAdapter().getCount(); 783 784 // Detect the case where a cursor that was previously invalidated has 785 // been repopulated with new data. 786 if (AdapterView.this.getAdapter().hasStableIds() && mInstanceState != null 787 && mOldItemCount == 0 && mItemCount > 0) { 788 AdapterView.this.onRestoreInstanceState(mInstanceState); 789 mInstanceState = null; 790 } else { 791 rememberSyncState(); 792 } 793 checkFocus(); 794 requestLayout(); 795 } 796 797 @Override 798 public void onInvalidated() { 799 mDataChanged = true; 800 801 if (AdapterView.this.getAdapter().hasStableIds()) { 802 // Remember the current state for the case where our hosting activity is being 803 // stopped and later restarted 804 mInstanceState = AdapterView.this.onSaveInstanceState(); 805 } 806 807 // Data is invalid so we should reset our state 808 mOldItemCount = mItemCount; 809 mItemCount = 0; 810 mSelectedPosition = INVALID_POSITION; 811 mSelectedRowId = INVALID_ROW_ID; 812 mNextSelectedPosition = INVALID_POSITION; 813 mNextSelectedRowId = INVALID_ROW_ID; 814 mNeedSync = false; 815 816 checkFocus(); 817 requestLayout(); 818 } 819 820 public void clearSavedState() { 821 mInstanceState = null; 822 } 823 } 824 825 @Override 826 protected void onDetachedFromWindow() { 827 super.onDetachedFromWindow(); 828 removeCallbacks(mSelectionNotifier); 829 } 830 831 private class SelectionNotifier implements Runnable { 832 public void run() { 833 if (mDataChanged) { 834 // Data has changed between when this SelectionNotifier 835 // was posted and now. We need to wait until the AdapterView 836 // has been synched to the new data. 837 if (getAdapter() != null) { 838 post(this); 839 } 840 } else { 841 fireOnSelected(); 842 } 843 } 844 } 845 846 void selectionChanged() { 847 if (mOnItemSelectedListener != null) { 848 if (mInLayout || mBlockLayoutRequests) { 849 // If we are in a layout traversal, defer notification 850 // by posting. This ensures that the view tree is 851 // in a consistent state and is able to accomodate 852 // new layout or invalidate requests. 853 if (mSelectionNotifier == null) { 854 mSelectionNotifier = new SelectionNotifier(); 855 } 856 post(mSelectionNotifier); 857 } else { 858 fireOnSelected(); 859 } 860 } 861 862 // we fire selection events here not in View 863 if (mSelectedPosition != ListView.INVALID_POSITION && isShown() && !isInTouchMode()) { 864 sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_SELECTED); 865 } 866 } 867 868 private void fireOnSelected() { 869 if (mOnItemSelectedListener == null) 870 return; 871 872 int selection = this.getSelectedItemPosition(); 873 if (selection >= 0) { 874 View v = getSelectedView(); 875 mOnItemSelectedListener.onItemSelected(this, v, selection, 876 getAdapter().getItemId(selection)); 877 } else { 878 mOnItemSelectedListener.onNothingSelected(this); 879 } 880 } 881 882 @Override 883 public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) { 884 final int eventType = event.getEventType(); 885 switch (eventType) { 886 case AccessibilityEvent.TYPE_VIEW_SCROLLED: 887 // Do not populate the text of scroll events. 888 return true; 889 case AccessibilityEvent.TYPE_VIEW_FOCUSED: 890 // This is an exceptional case which occurs when a window gets the 891 // focus and sends a focus event via its focused child to announce 892 // current focus/selection. AdapterView fires selection but not focus 893 // events so we change the event type here. 894 if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_FOCUSED) { 895 event.setEventType(AccessibilityEvent.TYPE_VIEW_SELECTED); 896 } 897 break; 898 } 899 900 View selectedView = getSelectedView(); 901 if (selectedView != null && selectedView.getVisibility() == VISIBLE) { 902 getSelectedView().dispatchPopulateAccessibilityEvent(event); 903 } 904 return false; 905 } 906 907 @Override 908 public boolean onRequestSendAccessibilityEvent(View child, AccessibilityEvent event) { 909 if (super.onRequestSendAccessibilityEvent(child, event)) { 910 // Add a record for ourselves as well. 911 AccessibilityEvent record = AccessibilityEvent.obtain(); 912 onInitializeAccessibilityEvent(record); 913 // Populate with the text of the requesting child. 914 child.dispatchPopulateAccessibilityEvent(record); 915 event.appendRecord(record); 916 return true; 917 } 918 return false; 919 } 920 921 @Override 922 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 923 super.onInitializeAccessibilityEvent(event); 924 925 View selectedView = getSelectedView(); 926 if (selectedView != null) { 927 event.setEnabled(selectedView.isEnabled()); 928 } 929 event.setItemCount(getCount()); 930 event.setCurrentItemIndex(getSelectedItemPosition()); 931 if (getChildCount() > 0) { 932 event.setFromIndex(getFirstVisiblePosition()); 933 event.setToIndex(getLastVisiblePosition()); 934 } 935 } 936 937 @Override 938 protected boolean canAnimate() { 939 return super.canAnimate() && mItemCount > 0; 940 } 941 942 void handleDataChanged() { 943 final int count = mItemCount; 944 boolean found = false; 945 946 if (count > 0) { 947 948 int newPos; 949 950 // Find the row we are supposed to sync to 951 if (mNeedSync) { 952 // Update this first, since setNextSelectedPositionInt inspects 953 // it 954 mNeedSync = false; 955 956 // See if we can find a position in the new data with the same 957 // id as the old selection 958 newPos = findSyncPosition(); 959 if (newPos >= 0) { 960 // Verify that new selection is selectable 961 int selectablePos = lookForSelectablePosition(newPos, true); 962 if (selectablePos == newPos) { 963 // Same row id is selected 964 setNextSelectedPositionInt(newPos); 965 found = true; 966 } 967 } 968 } 969 if (!found) { 970 // Try to use the same position if we can't find matching data 971 newPos = getSelectedItemPosition(); 972 973 // Pin position to the available range 974 if (newPos >= count) { 975 newPos = count - 1; 976 } 977 if (newPos < 0) { 978 newPos = 0; 979 } 980 981 // Make sure we select something selectable -- first look down 982 int selectablePos = lookForSelectablePosition(newPos, true); 983 if (selectablePos < 0) { 984 // Looking down didn't work -- try looking up 985 selectablePos = lookForSelectablePosition(newPos, false); 986 } 987 if (selectablePos >= 0) { 988 setNextSelectedPositionInt(selectablePos); 989 checkSelectionChanged(); 990 found = true; 991 } 992 } 993 } 994 if (!found) { 995 // Nothing is selected 996 mSelectedPosition = INVALID_POSITION; 997 mSelectedRowId = INVALID_ROW_ID; 998 mNextSelectedPosition = INVALID_POSITION; 999 mNextSelectedRowId = INVALID_ROW_ID; 1000 mNeedSync = false; 1001 checkSelectionChanged(); 1002 } 1003 } 1004 1005 void checkSelectionChanged() { 1006 if ((mSelectedPosition != mOldSelectedPosition) || (mSelectedRowId != mOldSelectedRowId)) { 1007 selectionChanged(); 1008 mOldSelectedPosition = mSelectedPosition; 1009 mOldSelectedRowId = mSelectedRowId; 1010 } 1011 } 1012 1013 /** 1014 * Searches the adapter for a position matching mSyncRowId. The search starts at mSyncPosition 1015 * and then alternates between moving up and moving down until 1) we find the right position, or 1016 * 2) we run out of time, or 3) we have looked at every position 1017 * 1018 * @return Position of the row that matches mSyncRowId, or {@link #INVALID_POSITION} if it can't 1019 * be found 1020 */ 1021 int findSyncPosition() { 1022 int count = mItemCount; 1023 1024 if (count == 0) { 1025 return INVALID_POSITION; 1026 } 1027 1028 long idToMatch = mSyncRowId; 1029 int seed = mSyncPosition; 1030 1031 // If there isn't a selection don't hunt for it 1032 if (idToMatch == INVALID_ROW_ID) { 1033 return INVALID_POSITION; 1034 } 1035 1036 // Pin seed to reasonable values 1037 seed = Math.max(0, seed); 1038 seed = Math.min(count - 1, seed); 1039 1040 long endTime = SystemClock.uptimeMillis() + SYNC_MAX_DURATION_MILLIS; 1041 1042 long rowId; 1043 1044 // first position scanned so far 1045 int first = seed; 1046 1047 // last position scanned so far 1048 int last = seed; 1049 1050 // True if we should move down on the next iteration 1051 boolean next = false; 1052 1053 // True when we have looked at the first item in the data 1054 boolean hitFirst; 1055 1056 // True when we have looked at the last item in the data 1057 boolean hitLast; 1058 1059 // Get the item ID locally (instead of getItemIdAtPosition), so 1060 // we need the adapter 1061 T adapter = getAdapter(); 1062 if (adapter == null) { 1063 return INVALID_POSITION; 1064 } 1065 1066 while (SystemClock.uptimeMillis() <= endTime) { 1067 rowId = adapter.getItemId(seed); 1068 if (rowId == idToMatch) { 1069 // Found it! 1070 return seed; 1071 } 1072 1073 hitLast = last == count - 1; 1074 hitFirst = first == 0; 1075 1076 if (hitLast && hitFirst) { 1077 // Looked at everything 1078 break; 1079 } 1080 1081 if (hitFirst || (next && !hitLast)) { 1082 // Either we hit the top, or we are trying to move down 1083 last++; 1084 seed = last; 1085 // Try going up next time 1086 next = false; 1087 } else if (hitLast || (!next && !hitFirst)) { 1088 // Either we hit the bottom, or we are trying to move up 1089 first--; 1090 seed = first; 1091 // Try going down next time 1092 next = true; 1093 } 1094 1095 } 1096 1097 return INVALID_POSITION; 1098 } 1099 1100 /** 1101 * Find a position that can be selected (i.e., is not a separator). 1102 * 1103 * @param position The starting position to look at. 1104 * @param lookDown Whether to look down for other positions. 1105 * @return The next selectable position starting at position and then searching either up or 1106 * down. Returns {@link #INVALID_POSITION} if nothing can be found. 1107 */ 1108 int lookForSelectablePosition(int position, boolean lookDown) { 1109 return position; 1110 } 1111 1112 /** 1113 * Utility to keep mSelectedPosition and mSelectedRowId in sync 1114 * @param position Our current position 1115 */ 1116 void setSelectedPositionInt(int position) { 1117 mSelectedPosition = position; 1118 mSelectedRowId = getItemIdAtPosition(position); 1119 } 1120 1121 /** 1122 * Utility to keep mNextSelectedPosition and mNextSelectedRowId in sync 1123 * @param position Intended value for mSelectedPosition the next time we go 1124 * through layout 1125 */ 1126 void setNextSelectedPositionInt(int position) { 1127 mNextSelectedPosition = position; 1128 mNextSelectedRowId = getItemIdAtPosition(position); 1129 // If we are trying to sync to the selection, update that too 1130 if (mNeedSync && mSyncMode == SYNC_SELECTED_POSITION && position >= 0) { 1131 mSyncPosition = position; 1132 mSyncRowId = mNextSelectedRowId; 1133 } 1134 } 1135 1136 /** 1137 * Remember enough information to restore the screen state when the data has 1138 * changed. 1139 * 1140 */ 1141 void rememberSyncState() { 1142 if (getChildCount() > 0) { 1143 mNeedSync = true; 1144 mSyncHeight = mLayoutHeight; 1145 if (mSelectedPosition >= 0) { 1146 // Sync the selection state 1147 View v = getChildAt(mSelectedPosition - mFirstPosition); 1148 mSyncRowId = mNextSelectedRowId; 1149 mSyncPosition = mNextSelectedPosition; 1150 if (v != null) { 1151 mSpecificTop = v.getTop(); 1152 } 1153 mSyncMode = SYNC_SELECTED_POSITION; 1154 } else { 1155 // Sync the based on the offset of the first view 1156 View v = getChildAt(0); 1157 T adapter = getAdapter(); 1158 if (mFirstPosition >= 0 && mFirstPosition < adapter.getCount()) { 1159 mSyncRowId = adapter.getItemId(mFirstPosition); 1160 } else { 1161 mSyncRowId = NO_ID; 1162 } 1163 mSyncPosition = mFirstPosition; 1164 if (v != null) { 1165 mSpecificTop = v.getTop(); 1166 } 1167 mSyncMode = SYNC_FIRST_POSITION; 1168 } 1169 } 1170 } 1171} 1172