ListView.java revision 4df2423a947bcd3f024cc3d3a1a315a8dc428598
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.content.res.TypedArray; 21import android.graphics.Canvas; 22import android.graphics.Rect; 23import android.graphics.drawable.Drawable; 24import android.graphics.drawable.ColorDrawable; 25import android.os.Parcel; 26import android.os.Parcelable; 27import android.util.AttributeSet; 28import android.util.SparseBooleanArray; 29import android.view.FocusFinder; 30import android.view.KeyEvent; 31import android.view.MotionEvent; 32import android.view.View; 33import android.view.ViewDebug; 34import android.view.ViewGroup; 35import android.view.ViewParent; 36import android.view.SoundEffectConstants; 37 38import com.google.android.collect.Lists; 39import com.android.internal.R; 40 41import java.util.ArrayList; 42 43/* 44 * Implementation Notes: 45 * 46 * Some terminology: 47 * 48 * index - index of the items that are currently visible 49 * position - index of the items in the cursor 50 */ 51 52 53/** 54 * A view that shows items in a vertically scrolling list. The items 55 * come from the {@link ListAdapter} associated with this view. 56 * 57 * @attr ref android.R.styleable#ListView_entries 58 * @attr ref android.R.styleable#ListView_divider 59 * @attr ref android.R.styleable#ListView_dividerHeight 60 * @attr ref android.R.styleable#ListView_choiceMode 61 * @attr ref android.R.styleable#ListView_headerDividersEnabled 62 * @attr ref android.R.styleable#ListView_footerDividersEnabled 63 */ 64public class ListView extends AbsListView { 65 /** 66 * Used to indicate a no preference for a position type. 67 */ 68 static final int NO_POSITION = -1; 69 70 /** 71 * Normal list that does not indicate choices 72 */ 73 public static final int CHOICE_MODE_NONE = 0; 74 75 /** 76 * The list allows up to one choice 77 */ 78 public static final int CHOICE_MODE_SINGLE = 1; 79 80 /** 81 * The list allows multiple choices 82 */ 83 public static final int CHOICE_MODE_MULTIPLE = 2; 84 85 /** 86 * When arrow scrolling, ListView will never scroll more than this factor 87 * times the height of the list. 88 */ 89 private static final float MAX_SCROLL_FACTOR = 0.33f; 90 91 /** 92 * When arrow scrolling, need a certain amount of pixels to preview next 93 * items. This is usually the fading edge, but if that is small enough, 94 * we want to make sure we preview at least this many pixels. 95 */ 96 private static final int MIN_SCROLL_PREVIEW_PIXELS = 2; 97 98 /** 99 * A class that represents a fixed view in a list, for example a header at the top 100 * or a footer at the bottom. 101 */ 102 public class FixedViewInfo { 103 /** The view to add to the list */ 104 public View view; 105 /** The data backing the view. This is returned from {@link ListAdapter#getItem(int)}. */ 106 public Object data; 107 /** <code>true</code> if the fixed view should be selectable in the list */ 108 public boolean isSelectable; 109 } 110 111 private ArrayList<FixedViewInfo> mHeaderViewInfos = Lists.newArrayList(); 112 private ArrayList<FixedViewInfo> mFooterViewInfos = Lists.newArrayList(); 113 114 Drawable mDivider; 115 int mDividerHeight; 116 private boolean mClipDivider; 117 private boolean mHeaderDividersEnabled; 118 private boolean mFooterDividersEnabled; 119 120 private boolean mAreAllItemsSelectable = true; 121 122 private boolean mItemsCanFocus = false; 123 124 private int mChoiceMode = CHOICE_MODE_NONE; 125 126 private SparseBooleanArray mCheckStates; 127 128 // used for temporary calculations. 129 private Rect mTempRect = new Rect(); 130 131 // the single allocated result per list view; kinda cheesey but avoids 132 // allocating these thingies too often. 133 private ArrowScrollFocusResult mArrowScrollFocusResult = new ArrowScrollFocusResult(); 134 135 public ListView(Context context) { 136 this(context, null); 137 } 138 139 public ListView(Context context, AttributeSet attrs) { 140 this(context, attrs, com.android.internal.R.attr.listViewStyle); 141 } 142 143 public ListView(Context context, AttributeSet attrs, int defStyle) { 144 super(context, attrs, defStyle); 145 146 TypedArray a = context.obtainStyledAttributes(attrs, 147 com.android.internal.R.styleable.ListView, defStyle, 0); 148 149 CharSequence[] entries = a.getTextArray( 150 com.android.internal.R.styleable.ListView_entries); 151 if (entries != null) { 152 setAdapter(new ArrayAdapter<CharSequence>(context, 153 com.android.internal.R.layout.simple_list_item_1, entries)); 154 } 155 156 final Drawable d = a.getDrawable(com.android.internal.R.styleable.ListView_divider); 157 if (d != null) { 158 // If a divider is specified use its intrinsic height for divider height 159 setDivider(d); 160 } 161 162 // Use the height specified, zero being the default 163 final int dividerHeight = a.getDimensionPixelSize( 164 com.android.internal.R.styleable.ListView_dividerHeight, 0); 165 if (dividerHeight != 0) { 166 setDividerHeight(dividerHeight); 167 } 168 169 mHeaderDividersEnabled = a.getBoolean(R.styleable.ListView_headerDividersEnabled, true); 170 mFooterDividersEnabled = a.getBoolean(R.styleable.ListView_footerDividersEnabled, true); 171 172 a.recycle(); 173 } 174 175 /** 176 * @return The maximum amount a list view will scroll in response to 177 * an arrow event. 178 */ 179 public int getMaxScrollAmount() { 180 return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop)); 181 } 182 183 /** 184 * Make sure views are touching the top or bottom edge, as appropriate for 185 * our gravity 186 */ 187 private void adjustViewsUpOrDown() { 188 final int childCount = getChildCount(); 189 int delta; 190 191 if (childCount > 0) { 192 View child; 193 194 if (!mStackFromBottom) { 195 // Uh-oh -- we came up short. Slide all views up to make them 196 // align with the top 197 child = getChildAt(0); 198 delta = child.getTop() - mListPadding.top; 199 if (mFirstPosition != 0) { 200 // It's OK to have some space above the first item if it is 201 // part of the vertical spacing 202 delta -= mDividerHeight; 203 } 204 if (delta < 0) { 205 // We only are looking to see if we are too low, not too high 206 delta = 0; 207 } 208 } else { 209 // we are too high, slide all views down to align with bottom 210 child = getChildAt(childCount - 1); 211 delta = child.getBottom() - (getHeight() - mListPadding.bottom); 212 213 if (mFirstPosition + childCount < mItemCount) { 214 // It's OK to have some space below the last item if it is 215 // part of the vertical spacing 216 delta += mDividerHeight; 217 } 218 219 if (delta > 0) { 220 delta = 0; 221 } 222 } 223 224 if (delta != 0) { 225 offsetChildrenTopAndBottom(-delta); 226 } 227 } 228 } 229 230 /** 231 * Add a fixed view to appear at the top of the list. If addHeaderView is 232 * called more than once, the views will appear in the order they were 233 * added. Views added using this call can take focus if they want. 234 * <p> 235 * NOTE: Call this before calling setAdapter. This is so ListView can wrap 236 * the supplied cursor with one that that will also account for header 237 * views. 238 * 239 * @param v The view to add. 240 * @param data Data to associate with this view 241 * @param isSelectable whether the item is selectable 242 */ 243 public void addHeaderView(View v, Object data, boolean isSelectable) { 244 245 if (mAdapter != null) { 246 throw new IllegalStateException( 247 "Cannot add header view to list -- setAdapter has already been called."); 248 } 249 250 FixedViewInfo info = new FixedViewInfo(); 251 info.view = v; 252 info.data = data; 253 info.isSelectable = isSelectable; 254 mHeaderViewInfos.add(info); 255 } 256 257 /** 258 * Add a fixed view to appear at the top of the list. If addHeaderView is 259 * called more than once, the views will appear in the order they were 260 * added. Views added using this call can take focus if they want. 261 * <p> 262 * NOTE: Call this before calling setAdapter. This is so ListView can wrap 263 * the supplied cursor with one that that will also account for header 264 * views. 265 * 266 * @param v The view to add. 267 */ 268 public void addHeaderView(View v) { 269 addHeaderView(v, null, true); 270 } 271 272 @Override 273 public int getHeaderViewsCount() { 274 return mHeaderViewInfos.size(); 275 } 276 277 /** 278 * Removes a previously-added header view. 279 * 280 * @param v The view to remove 281 * @return true if the view was removed, false if the view was not a header 282 * view 283 */ 284 public boolean removeHeaderView(View v) { 285 if (mHeaderViewInfos.size() > 0) { 286 boolean result = false; 287 if (((HeaderViewListAdapter) mAdapter).removeHeader(v)) { 288 mDataSetObserver.onChanged(); 289 result = true; 290 } 291 removeFixedViewInfo(v, mHeaderViewInfos); 292 return result; 293 } 294 return false; 295 } 296 297 private void removeFixedViewInfo(View v, ArrayList<FixedViewInfo> where) { 298 int len = where.size(); 299 for (int i = 0; i < len; ++i) { 300 FixedViewInfo info = where.get(i); 301 if (info.view == v) { 302 where.remove(i); 303 break; 304 } 305 } 306 } 307 308 /** 309 * Add a fixed view to appear at the bottom of the list. If addFooterView is 310 * called more than once, the views will appear in the order they were 311 * added. Views added using this call can take focus if they want. 312 * <p> 313 * NOTE: Call this before calling setAdapter. This is so ListView can wrap 314 * the supplied cursor with one that that will also account for header 315 * views. 316 * 317 * @param v The view to add. 318 * @param data Data to associate with this view 319 * @param isSelectable true if the footer view can be selected 320 */ 321 public void addFooterView(View v, Object data, boolean isSelectable) { 322 FixedViewInfo info = new FixedViewInfo(); 323 info.view = v; 324 info.data = data; 325 info.isSelectable = isSelectable; 326 mFooterViewInfos.add(info); 327 328 // in the case of re-adding a footer view, or adding one later on, 329 // we need to notify the observer 330 if (mDataSetObserver != null) { 331 mDataSetObserver.onChanged(); 332 } 333 } 334 335 /** 336 * Add a fixed view to appear at the bottom of the list. If addFooterView is called more 337 * than once, the views will appear in the order they were added. Views added using 338 * this call can take focus if they want. 339 * <p>NOTE: Call this before calling setAdapter. This is so ListView can wrap the supplied 340 * cursor with one that that will also account for header views. 341 * 342 * 343 * @param v The view to add. 344 */ 345 public void addFooterView(View v) { 346 addFooterView(v, null, true); 347 } 348 349 @Override 350 public int getFooterViewsCount() { 351 return mFooterViewInfos.size(); 352 } 353 354 /** 355 * Removes a previously-added footer view. 356 * 357 * @param v The view to remove 358 * @return 359 * true if the view was removed, false if the view was not a footer view 360 */ 361 public boolean removeFooterView(View v) { 362 if (mFooterViewInfos.size() > 0) { 363 boolean result = false; 364 if (((HeaderViewListAdapter) mAdapter).removeFooter(v)) { 365 mDataSetObserver.onChanged(); 366 result = true; 367 } 368 removeFixedViewInfo(v, mFooterViewInfos); 369 return result; 370 } 371 return false; 372 } 373 374 /** 375 * Returns the adapter currently in use in this ListView. The returned adapter 376 * might not be the same adapter passed to {@link #setAdapter(ListAdapter)} but 377 * might be a {@link WrapperListAdapter}. 378 * 379 * @return The adapter currently used to display data in this ListView. 380 * 381 * @see #setAdapter(ListAdapter) 382 */ 383 @Override 384 public ListAdapter getAdapter() { 385 return mAdapter; 386 } 387 388 /** 389 * Sets the data behind this ListView. 390 * 391 * The adapter passed to this method may be wrapped by a {@link WrapperListAdapter}, 392 * depending on the ListView features currently in use. For instance, adding 393 * headers and/or footers will cause the adapter to be wrapped. 394 * 395 * @param adapter The ListAdapter which is responsible for maintaining the 396 * data backing this list and for producing a view to represent an 397 * item in that data set. 398 * 399 * @see #getAdapter() 400 */ 401 @Override 402 public void setAdapter(ListAdapter adapter) { 403 if (null != mAdapter) { 404 mAdapter.unregisterDataSetObserver(mDataSetObserver); 405 } 406 407 resetList(); 408 mRecycler.clear(); 409 410 if (mHeaderViewInfos.size() > 0|| mFooterViewInfos.size() > 0) { 411 mAdapter = new HeaderViewListAdapter(mHeaderViewInfos, mFooterViewInfos, adapter); 412 } else { 413 mAdapter = adapter; 414 } 415 416 mOldSelectedPosition = INVALID_POSITION; 417 mOldSelectedRowId = INVALID_ROW_ID; 418 if (mAdapter != null) { 419 mAreAllItemsSelectable = mAdapter.areAllItemsEnabled(); 420 mOldItemCount = mItemCount; 421 mItemCount = mAdapter.getCount(); 422 checkFocus(); 423 424 mDataSetObserver = new AdapterDataSetObserver(); 425 mAdapter.registerDataSetObserver(mDataSetObserver); 426 427 mRecycler.setViewTypeCount(mAdapter.getViewTypeCount()); 428 429 int position; 430 if (mStackFromBottom) { 431 position = lookForSelectablePosition(mItemCount - 1, false); 432 } else { 433 position = lookForSelectablePosition(0, true); 434 } 435 setSelectedPositionInt(position); 436 setNextSelectedPositionInt(position); 437 438 if (mItemCount == 0) { 439 // Nothing selected 440 checkSelectionChanged(); 441 } 442 443 } else { 444 mAreAllItemsSelectable = true; 445 checkFocus(); 446 // Nothing selected 447 checkSelectionChanged(); 448 } 449 450 if (mCheckStates != null) { 451 mCheckStates.clear(); 452 } 453 454 requestLayout(); 455 } 456 457 458 /** 459 * The list is empty. Clear everything out. 460 */ 461 @Override 462 void resetList() { 463 super.resetList(); 464 mLayoutMode = LAYOUT_NORMAL; 465 } 466 467 /** 468 * @return Whether the list needs to show the top fading edge 469 */ 470 private boolean showingTopFadingEdge() { 471 final int listTop = mScrollY + mListPadding.top; 472 return (mFirstPosition > 0) || (getChildAt(0).getTop() > listTop); 473 } 474 475 /** 476 * @return Whether the list needs to show the bottom fading edge 477 */ 478 private boolean showingBottomFadingEdge() { 479 final int childCount = getChildCount(); 480 final int bottomOfBottomChild = getChildAt(childCount - 1).getBottom(); 481 final int lastVisiblePosition = mFirstPosition + childCount - 1; 482 483 final int listBottom = mScrollY + getHeight() - mListPadding.bottom; 484 485 return (lastVisiblePosition < mItemCount - 1) 486 || (bottomOfBottomChild < listBottom); 487 } 488 489 490 @Override 491 public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) { 492 493 int rectTopWithinChild = rect.top; 494 495 // offset so rect is in coordinates of the this view 496 rect.offset(child.getLeft(), child.getTop()); 497 rect.offset(-child.getScrollX(), -child.getScrollY()); 498 499 final int height = getHeight(); 500 int listUnfadedTop = getScrollY(); 501 int listUnfadedBottom = listUnfadedTop + height; 502 final int fadingEdge = getVerticalFadingEdgeLength(); 503 504 if (showingTopFadingEdge()) { 505 // leave room for top fading edge as long as rect isn't at very top 506 if ((mSelectedPosition > 0) || (rectTopWithinChild > fadingEdge)) { 507 listUnfadedTop += fadingEdge; 508 } 509 } 510 511 int childCount = getChildCount(); 512 int bottomOfBottomChild = getChildAt(childCount - 1).getBottom(); 513 514 if (showingBottomFadingEdge()) { 515 // leave room for bottom fading edge as long as rect isn't at very bottom 516 if ((mSelectedPosition < mItemCount - 1) 517 || (rect.bottom < (bottomOfBottomChild - fadingEdge))) { 518 listUnfadedBottom -= fadingEdge; 519 } 520 } 521 522 int scrollYDelta = 0; 523 524 if (rect.bottom > listUnfadedBottom && rect.top > listUnfadedTop) { 525 // need to MOVE DOWN to get it in view: move down just enough so 526 // that the entire rectangle is in view (or at least the first 527 // screen size chunk). 528 529 if (rect.height() > height) { 530 // just enough to get screen size chunk on 531 scrollYDelta += (rect.top - listUnfadedTop); 532 } else { 533 // get entire rect at bottom of screen 534 scrollYDelta += (rect.bottom - listUnfadedBottom); 535 } 536 537 // make sure we aren't scrolling beyond the end of our children 538 int distanceToBottom = bottomOfBottomChild - listUnfadedBottom; 539 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 540 } else if (rect.top < listUnfadedTop && rect.bottom < listUnfadedBottom) { 541 // need to MOVE UP to get it in view: move up just enough so that 542 // entire rectangle is in view (or at least the first screen 543 // size chunk of it). 544 545 if (rect.height() > height) { 546 // screen size chunk 547 scrollYDelta -= (listUnfadedBottom - rect.bottom); 548 } else { 549 // entire rect at top 550 scrollYDelta -= (listUnfadedTop - rect.top); 551 } 552 553 // make sure we aren't scrolling any further than the top our children 554 int top = getChildAt(0).getTop(); 555 int deltaToTop = top - listUnfadedTop; 556 scrollYDelta = Math.max(scrollYDelta, deltaToTop); 557 } 558 559 final boolean scroll = scrollYDelta != 0; 560 if (scroll) { 561 scrollListItemsBy(-scrollYDelta); 562 positionSelector(child); 563 mSelectedTop = child.getTop(); 564 invalidate(); 565 } 566 return scroll; 567 } 568 569 /** 570 * {@inheritDoc} 571 */ 572 @Override 573 void fillGap(boolean down) { 574 final int count = getChildCount(); 575 if (down) { 576 final int startOffset = count > 0 ? getChildAt(count - 1).getBottom() + mDividerHeight : 577 getListPaddingTop(); 578 fillDown(mFirstPosition + count, startOffset); 579 correctTooHigh(getChildCount()); 580 } else { 581 final int startOffset = count > 0 ? getChildAt(0).getTop() - mDividerHeight : 582 getHeight() - getListPaddingBottom(); 583 fillUp(mFirstPosition - 1, startOffset); 584 correctTooLow(getChildCount()); 585 } 586 } 587 588 /** 589 * Fills the list from pos down to the end of the list view. 590 * 591 * @param pos The first position to put in the list 592 * 593 * @param nextTop The location where the top of the item associated with pos 594 * should be drawn 595 * 596 * @return The view that is currently selected, if it happens to be in the 597 * range that we draw. 598 */ 599 private View fillDown(int pos, int nextTop) { 600 View selectedView = null; 601 602 int end = (mBottom - mTop) - mListPadding.bottom; 603 604 while (nextTop < end && pos < mItemCount) { 605 // is this the selected item? 606 boolean selected = pos == mSelectedPosition; 607 View child = makeAndAddView(pos, nextTop, true, mListPadding.left, selected); 608 609 nextTop = child.getBottom() + mDividerHeight; 610 if (selected) { 611 selectedView = child; 612 } 613 pos++; 614 } 615 616 return selectedView; 617 } 618 619 /** 620 * Fills the list from pos up to the top of the list view. 621 * 622 * @param pos The first position to put in the list 623 * 624 * @param nextBottom The location where the bottom of the item associated 625 * with pos should be drawn 626 * 627 * @return The view that is currently selected 628 */ 629 private View fillUp(int pos, int nextBottom) { 630 View selectedView = null; 631 632 int end = mListPadding.top; 633 634 while (nextBottom > end && pos >= 0) { 635 // is this the selected item? 636 boolean selected = pos == mSelectedPosition; 637 View child = makeAndAddView(pos, nextBottom, false, mListPadding.left, selected); 638 nextBottom = child.getTop() - mDividerHeight; 639 if (selected) { 640 selectedView = child; 641 } 642 pos--; 643 } 644 645 mFirstPosition = pos + 1; 646 647 return selectedView; 648 } 649 650 /** 651 * Fills the list from top to bottom, starting with mFirstPosition 652 * 653 * @param nextTop The location where the top of the first item should be 654 * drawn 655 * 656 * @return The view that is currently selected 657 */ 658 private View fillFromTop(int nextTop) { 659 mFirstPosition = Math.min(mFirstPosition, mSelectedPosition); 660 mFirstPosition = Math.min(mFirstPosition, mItemCount - 1); 661 if (mFirstPosition < 0) { 662 mFirstPosition = 0; 663 } 664 return fillDown(mFirstPosition, nextTop); 665 } 666 667 668 /** 669 * Put mSelectedPosition in the middle of the screen and then build up and 670 * down from there. This method forces mSelectedPosition to the center. 671 * 672 * @param childrenTop Top of the area in which children can be drawn, as 673 * measured in pixels 674 * @param childrenBottom Bottom of the area in which children can be drawn, 675 * as measured in pixels 676 * @return Currently selected view 677 */ 678 private View fillFromMiddle(int childrenTop, int childrenBottom) { 679 int height = childrenBottom - childrenTop; 680 681 int position = reconcileSelectedPosition(); 682 683 View sel = makeAndAddView(position, childrenTop, true, 684 mListPadding.left, true); 685 mFirstPosition = position; 686 687 int selHeight = sel.getMeasuredHeight(); 688 if (selHeight <= height) { 689 sel.offsetTopAndBottom((height - selHeight) / 2); 690 } 691 692 fillAboveAndBelow(sel, position); 693 694 if (!mStackFromBottom) { 695 correctTooHigh(getChildCount()); 696 } else { 697 correctTooLow(getChildCount()); 698 } 699 700 return sel; 701 } 702 703 /** 704 * Once the selected view as been placed, fill up the visible area above and 705 * below it. 706 * 707 * @param sel The selected view 708 * @param position The position corresponding to sel 709 */ 710 private void fillAboveAndBelow(View sel, int position) { 711 final int dividerHeight = mDividerHeight; 712 if (!mStackFromBottom) { 713 fillUp(position - 1, sel.getTop() - dividerHeight); 714 adjustViewsUpOrDown(); 715 fillDown(position + 1, sel.getBottom() + dividerHeight); 716 } else { 717 fillDown(position + 1, sel.getBottom() + dividerHeight); 718 adjustViewsUpOrDown(); 719 fillUp(position - 1, sel.getTop() - dividerHeight); 720 } 721 } 722 723 724 /** 725 * Fills the grid based on positioning the new selection at a specific 726 * location. The selection may be moved so that it does not intersect the 727 * faded edges. The grid is then filled upwards and downwards from there. 728 * 729 * @param selectedTop Where the selected item should be 730 * @param childrenTop Where to start drawing children 731 * @param childrenBottom Last pixel where children can be drawn 732 * @return The view that currently has selection 733 */ 734 private View fillFromSelection(int selectedTop, int childrenTop, int childrenBottom) { 735 int fadingEdgeLength = getVerticalFadingEdgeLength(); 736 final int selectedPosition = mSelectedPosition; 737 738 View sel; 739 740 final int topSelectionPixel = getTopSelectionPixel(childrenTop, fadingEdgeLength, 741 selectedPosition); 742 final int bottomSelectionPixel = getBottomSelectionPixel(childrenBottom, fadingEdgeLength, 743 selectedPosition); 744 745 sel = makeAndAddView(selectedPosition, selectedTop, true, mListPadding.left, true); 746 747 748 // Some of the newly selected item extends below the bottom of the list 749 if (sel.getBottom() > bottomSelectionPixel) { 750 // Find space available above the selection into which we can scroll 751 // upwards 752 final int spaceAbove = sel.getTop() - topSelectionPixel; 753 754 // Find space required to bring the bottom of the selected item 755 // fully into view 756 final int spaceBelow = sel.getBottom() - bottomSelectionPixel; 757 final int offset = Math.min(spaceAbove, spaceBelow); 758 759 // Now offset the selected item to get it into view 760 sel.offsetTopAndBottom(-offset); 761 } else if (sel.getTop() < topSelectionPixel) { 762 // Find space required to bring the top of the selected item fully 763 // into view 764 final int spaceAbove = topSelectionPixel - sel.getTop(); 765 766 // Find space available below the selection into which we can scroll 767 // downwards 768 final int spaceBelow = bottomSelectionPixel - sel.getBottom(); 769 final int offset = Math.min(spaceAbove, spaceBelow); 770 771 // Offset the selected item to get it into view 772 sel.offsetTopAndBottom(offset); 773 } 774 775 // Fill in views above and below 776 fillAboveAndBelow(sel, selectedPosition); 777 778 if (!mStackFromBottom) { 779 correctTooHigh(getChildCount()); 780 } else { 781 correctTooLow(getChildCount()); 782 } 783 784 return sel; 785 } 786 787 /** 788 * Calculate the bottom-most pixel we can draw the selection into 789 * 790 * @param childrenBottom Bottom pixel were children can be drawn 791 * @param fadingEdgeLength Length of the fading edge in pixels, if present 792 * @param selectedPosition The position that will be selected 793 * @return The bottom-most pixel we can draw the selection into 794 */ 795 private int getBottomSelectionPixel(int childrenBottom, int fadingEdgeLength, 796 int selectedPosition) { 797 int bottomSelectionPixel = childrenBottom; 798 if (selectedPosition != mItemCount - 1) { 799 bottomSelectionPixel -= fadingEdgeLength; 800 } 801 return bottomSelectionPixel; 802 } 803 804 /** 805 * Calculate the top-most pixel we can draw the selection into 806 * 807 * @param childrenTop Top pixel were children can be drawn 808 * @param fadingEdgeLength Length of the fading edge in pixels, if present 809 * @param selectedPosition The position that will be selected 810 * @return The top-most pixel we can draw the selection into 811 */ 812 private int getTopSelectionPixel(int childrenTop, int fadingEdgeLength, int selectedPosition) { 813 // first pixel we can draw the selection into 814 int topSelectionPixel = childrenTop; 815 if (selectedPosition > 0) { 816 topSelectionPixel += fadingEdgeLength; 817 } 818 return topSelectionPixel; 819 } 820 821 822 /** 823 * Fills the list based on positioning the new selection relative to the old 824 * selection. The new selection will be placed at, above, or below the 825 * location of the new selection depending on how the selection is moving. 826 * The selection will then be pinned to the visible part of the screen, 827 * excluding the edges that are faded. The list is then filled upwards and 828 * downwards from there. 829 * 830 * @param oldSel The old selected view. Useful for trying to put the new 831 * selection in the same place 832 * @param newSel The view that is to become selected. Useful for trying to 833 * put the new selection in the same place 834 * @param delta Which way we are moving 835 * @param childrenTop Where to start drawing children 836 * @param childrenBottom Last pixel where children can be drawn 837 * @return The view that currently has selection 838 */ 839 private View moveSelection(View oldSel, View newSel, int delta, int childrenTop, 840 int childrenBottom) { 841 int fadingEdgeLength = getVerticalFadingEdgeLength(); 842 final int selectedPosition = mSelectedPosition; 843 844 View sel; 845 846 final int topSelectionPixel = getTopSelectionPixel(childrenTop, fadingEdgeLength, 847 selectedPosition); 848 final int bottomSelectionPixel = getBottomSelectionPixel(childrenTop, fadingEdgeLength, 849 selectedPosition); 850 851 if (delta > 0) { 852 /* 853 * Case 1: Scrolling down. 854 */ 855 856 /* 857 * Before After 858 * | | | | 859 * +-------+ +-------+ 860 * | A | | A | 861 * | 1 | => +-------+ 862 * +-------+ | B | 863 * | B | | 2 | 864 * +-------+ +-------+ 865 * | | | | 866 * 867 * Try to keep the top of the previously selected item where it was. 868 * oldSel = A 869 * sel = B 870 */ 871 872 // Put oldSel (A) where it belongs 873 oldSel = makeAndAddView(selectedPosition - 1, oldSel.getTop(), true, 874 mListPadding.left, false); 875 876 final int dividerHeight = mDividerHeight; 877 878 // Now put the new selection (B) below that 879 sel = makeAndAddView(selectedPosition, oldSel.getBottom() + dividerHeight, true, 880 mListPadding.left, true); 881 882 // Some of the newly selected item extends below the bottom of the list 883 if (sel.getBottom() > bottomSelectionPixel) { 884 885 // Find space available above the selection into which we can scroll upwards 886 int spaceAbove = sel.getTop() - topSelectionPixel; 887 888 // Find space required to bring the bottom of the selected item fully into view 889 int spaceBelow = sel.getBottom() - bottomSelectionPixel; 890 891 // Don't scroll more than half the height of the list 892 int halfVerticalSpace = (childrenBottom - childrenTop) / 2; 893 int offset = Math.min(spaceAbove, spaceBelow); 894 offset = Math.min(offset, halfVerticalSpace); 895 896 // We placed oldSel, so offset that item 897 oldSel.offsetTopAndBottom(-offset); 898 // Now offset the selected item to get it into view 899 sel.offsetTopAndBottom(-offset); 900 } 901 902 // Fill in views above and below 903 if (!mStackFromBottom) { 904 fillUp(mSelectedPosition - 2, sel.getTop() - dividerHeight); 905 adjustViewsUpOrDown(); 906 fillDown(mSelectedPosition + 1, sel.getBottom() + dividerHeight); 907 } else { 908 fillDown(mSelectedPosition + 1, sel.getBottom() + dividerHeight); 909 adjustViewsUpOrDown(); 910 fillUp(mSelectedPosition - 2, sel.getTop() - dividerHeight); 911 } 912 } else if (delta < 0) { 913 /* 914 * Case 2: Scrolling up. 915 */ 916 917 /* 918 * Before After 919 * | | | | 920 * +-------+ +-------+ 921 * | A | | A | 922 * +-------+ => | 1 | 923 * | B | +-------+ 924 * | 2 | | B | 925 * +-------+ +-------+ 926 * | | | | 927 * 928 * Try to keep the top of the item about to become selected where it was. 929 * newSel = A 930 * olSel = B 931 */ 932 933 if (newSel != null) { 934 // Try to position the top of newSel (A) where it was before it was selected 935 sel = makeAndAddView(selectedPosition, newSel.getTop(), true, mListPadding.left, 936 true); 937 } else { 938 // If (A) was not on screen and so did not have a view, position 939 // it above the oldSel (B) 940 sel = makeAndAddView(selectedPosition, oldSel.getTop(), false, mListPadding.left, 941 true); 942 } 943 944 // Some of the newly selected item extends above the top of the list 945 if (sel.getTop() < topSelectionPixel) { 946 // Find space required to bring the top of the selected item fully into view 947 int spaceAbove = topSelectionPixel - sel.getTop(); 948 949 // Find space available below the selection into which we can scroll downwards 950 int spaceBelow = bottomSelectionPixel - sel.getBottom(); 951 952 // Don't scroll more than half the height of the list 953 int halfVerticalSpace = (childrenBottom - childrenTop) / 2; 954 int offset = Math.min(spaceAbove, spaceBelow); 955 offset = Math.min(offset, halfVerticalSpace); 956 957 // Offset the selected item to get it into view 958 sel.offsetTopAndBottom(offset); 959 } 960 961 // Fill in views above and below 962 fillAboveAndBelow(sel, selectedPosition); 963 } else { 964 965 int oldTop = oldSel.getTop(); 966 967 /* 968 * Case 3: Staying still 969 */ 970 sel = makeAndAddView(selectedPosition, oldTop, true, mListPadding.left, true); 971 972 // We're staying still... 973 if (oldTop < childrenTop) { 974 // ... but the top of the old selection was off screen. 975 // (This can happen if the data changes size out from under us) 976 int newBottom = sel.getBottom(); 977 if (newBottom < childrenTop + 20) { 978 // Not enough visible -- bring it onscreen 979 sel.offsetTopAndBottom(childrenTop - sel.getTop()); 980 } 981 } 982 983 // Fill in views above and below 984 fillAboveAndBelow(sel, selectedPosition); 985 } 986 987 return sel; 988 } 989 990 @Override 991 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 992 // Sets up mListPadding 993 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 994 995 int widthMode = MeasureSpec.getMode(widthMeasureSpec); 996 int heightMode = MeasureSpec.getMode(heightMeasureSpec); 997 int widthSize = MeasureSpec.getSize(widthMeasureSpec); 998 int heightSize = MeasureSpec.getSize(heightMeasureSpec); 999 1000 int childWidth = 0; 1001 int childHeight = 0; 1002 1003 mItemCount = mAdapter == null ? 0 : mAdapter.getCount(); 1004 if (mItemCount > 0 && (widthMode == MeasureSpec.UNSPECIFIED || 1005 heightMode == MeasureSpec.UNSPECIFIED)) { 1006 final View child = obtainView(0); 1007 1008 measureScrapChild(child, 0, widthMeasureSpec); 1009 1010 childWidth = child.getMeasuredWidth(); 1011 childHeight = child.getMeasuredHeight(); 1012 1013 if (recycleOnMeasure()) { 1014 mRecycler.addScrapView(child); 1015 } 1016 } 1017 1018 if (widthMode == MeasureSpec.UNSPECIFIED) { 1019 widthSize = mListPadding.left + mListPadding.right + childWidth + 1020 getVerticalScrollbarWidth(); 1021 } 1022 1023 if (heightMode == MeasureSpec.UNSPECIFIED) { 1024 heightSize = mListPadding.top + mListPadding.bottom + childHeight + 1025 getVerticalFadingEdgeLength() * 2; 1026 } 1027 1028 if (heightMode == MeasureSpec.AT_MOST) { 1029 // TODO: after first layout we should maybe start at the first visible position, not 0 1030 heightSize = measureHeightOfChildren(widthMeasureSpec, 0, NO_POSITION, heightSize, -1); 1031 } 1032 1033 setMeasuredDimension(widthSize, heightSize); 1034 mWidthMeasureSpec = widthMeasureSpec; 1035 } 1036 1037 private void measureScrapChild(View child, int position, int widthMeasureSpec) { 1038 LayoutParams p = (LayoutParams) child.getLayoutParams(); 1039 if (p == null) { 1040 p = new LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, 1041 ViewGroup.LayoutParams.WRAP_CONTENT, 0); 1042 child.setLayoutParams(p); 1043 } 1044 p.viewType = mAdapter.getItemViewType(position); 1045 1046 int childWidthSpec = ViewGroup.getChildMeasureSpec(widthMeasureSpec, 1047 mListPadding.left + mListPadding.right, p.width); 1048 int lpHeight = p.height; 1049 int childHeightSpec; 1050 if (lpHeight > 0) { 1051 childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY); 1052 } else { 1053 childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1054 } 1055 child.measure(childWidthSpec, childHeightSpec); 1056 } 1057 1058 /** 1059 * @return True to recycle the views used to measure this ListView in 1060 * UNSPECIFIED/AT_MOST modes, false otherwise. 1061 * @hide 1062 */ 1063 protected boolean recycleOnMeasure() { 1064 return true; 1065 } 1066 1067 /** 1068 * Measures the height of the given range of children (inclusive) and 1069 * returns the height with this ListView's padding and divider heights 1070 * included. If maxHeight is provided, the measuring will stop when the 1071 * current height reaches maxHeight. 1072 * 1073 * @param widthMeasureSpec The width measure spec to be given to a child's 1074 * {@link View#measure(int, int)}. 1075 * @param startPosition The position of the first child to be shown. 1076 * @param endPosition The (inclusive) position of the last child to be 1077 * shown. Specify {@link #NO_POSITION} if the last child should be 1078 * the last available child from the adapter. 1079 * @param maxHeight The maximum height that will be returned (if all the 1080 * children don't fit in this value, this value will be 1081 * returned). 1082 * @param disallowPartialChildPosition In general, whether the returned 1083 * height should only contain entire children. This is more 1084 * powerful--it is the first inclusive position at which partial 1085 * children will not be allowed. Example: it looks nice to have 1086 * at least 3 completely visible children, and in portrait this 1087 * will most likely fit; but in landscape there could be times 1088 * when even 2 children can not be completely shown, so a value 1089 * of 2 (remember, inclusive) would be good (assuming 1090 * startPosition is 0). 1091 * @return The height of this ListView with the given children. 1092 */ 1093 final int measureHeightOfChildren(int widthMeasureSpec, int startPosition, int endPosition, 1094 final int maxHeight, int disallowPartialChildPosition) { 1095 1096 final ListAdapter adapter = mAdapter; 1097 if (adapter == null) { 1098 return mListPadding.top + mListPadding.bottom; 1099 } 1100 1101 // Include the padding of the list 1102 int returnedHeight = mListPadding.top + mListPadding.bottom; 1103 final int dividerHeight = ((mDividerHeight > 0) && mDivider != null) ? mDividerHeight : 0; 1104 // The previous height value that was less than maxHeight and contained 1105 // no partial children 1106 int prevHeightWithoutPartialChild = 0; 1107 int i; 1108 View child; 1109 1110 // mItemCount - 1 since endPosition parameter is inclusive 1111 endPosition = (endPosition == NO_POSITION) ? adapter.getCount() - 1 : endPosition; 1112 final AbsListView.RecycleBin recycleBin = mRecycler; 1113 final boolean recyle = recycleOnMeasure(); 1114 1115 for (i = startPosition; i <= endPosition; ++i) { 1116 child = obtainView(i); 1117 1118 measureScrapChild(child, i, widthMeasureSpec); 1119 1120 if (i > 0) { 1121 // Count the divider for all but one child 1122 returnedHeight += dividerHeight; 1123 } 1124 1125 // Recycle the view before we possibly return from the method 1126 if (recyle) { 1127 recycleBin.addScrapView(child); 1128 } 1129 1130 returnedHeight += child.getMeasuredHeight(); 1131 1132 if (returnedHeight >= maxHeight) { 1133 // We went over, figure out which height to return. If returnedHeight > maxHeight, 1134 // then the i'th position did not fit completely. 1135 return (disallowPartialChildPosition >= 0) // Disallowing is enabled (> -1) 1136 && (i > disallowPartialChildPosition) // We've past the min pos 1137 && (prevHeightWithoutPartialChild > 0) // We have a prev height 1138 && (returnedHeight != maxHeight) // i'th child did not fit completely 1139 ? prevHeightWithoutPartialChild 1140 : maxHeight; 1141 } 1142 1143 if ((disallowPartialChildPosition >= 0) && (i >= disallowPartialChildPosition)) { 1144 prevHeightWithoutPartialChild = returnedHeight; 1145 } 1146 } 1147 1148 // At this point, we went through the range of children, and they each 1149 // completely fit, so return the returnedHeight 1150 return returnedHeight; 1151 } 1152 1153 @Override 1154 int findMotionRow(int y) { 1155 int childCount = getChildCount(); 1156 if (childCount > 0) { 1157 for (int i = 0; i < childCount; i++) { 1158 View v = getChildAt(i); 1159 if (y <= v.getBottom()) { 1160 return mFirstPosition + i; 1161 } 1162 } 1163 return mFirstPosition + childCount - 1; 1164 } 1165 return INVALID_POSITION; 1166 } 1167 1168 /** 1169 * Put a specific item at a specific location on the screen and then build 1170 * up and down from there. 1171 * 1172 * @param position The reference view to use as the starting point 1173 * @param top Pixel offset from the top of this view to the top of the 1174 * reference view. 1175 * 1176 * @return The selected view, or null if the selected view is outside the 1177 * visible area. 1178 */ 1179 private View fillSpecific(int position, int top) { 1180 boolean tempIsSelected = position == mSelectedPosition; 1181 View temp = makeAndAddView(position, top, true, mListPadding.left, tempIsSelected); 1182 // Possibly changed again in fillUp if we add rows above this one. 1183 mFirstPosition = position; 1184 1185 View above; 1186 View below; 1187 1188 final int dividerHeight = mDividerHeight; 1189 if (!mStackFromBottom) { 1190 above = fillUp(position - 1, temp.getTop() - dividerHeight); 1191 // This will correct for the top of the first view not touching the top of the list 1192 adjustViewsUpOrDown(); 1193 below = fillDown(position + 1, temp.getBottom() + dividerHeight); 1194 int childCount = getChildCount(); 1195 if (childCount > 0) { 1196 correctTooHigh(childCount); 1197 } 1198 } else { 1199 below = fillDown(position + 1, temp.getBottom() + dividerHeight); 1200 // This will correct for the bottom of the last view not touching the bottom of the list 1201 adjustViewsUpOrDown(); 1202 above = fillUp(position - 1, temp.getTop() - dividerHeight); 1203 int childCount = getChildCount(); 1204 if (childCount > 0) { 1205 correctTooLow(childCount); 1206 } 1207 } 1208 1209 if (tempIsSelected) { 1210 return temp; 1211 } else if (above != null) { 1212 return above; 1213 } else { 1214 return below; 1215 } 1216 } 1217 1218 /** 1219 * Check if we have dragged the bottom of the list too high (we have pushed the 1220 * top element off the top of the screen when we did not need to). Correct by sliding 1221 * everything back down. 1222 * 1223 * @param childCount Number of children 1224 */ 1225 private void correctTooHigh(int childCount) { 1226 // First see if the last item is visible. If it is not, it is OK for the 1227 // top of the list to be pushed up. 1228 int lastPosition = mFirstPosition + childCount - 1; 1229 if (lastPosition == mItemCount - 1 && childCount > 0) { 1230 1231 // Get the last child ... 1232 final View lastChild = getChildAt(childCount - 1); 1233 1234 // ... and its bottom edge 1235 final int lastBottom = lastChild.getBottom(); 1236 1237 // This is bottom of our drawable area 1238 final int end = (mBottom - mTop) - mListPadding.bottom; 1239 1240 // This is how far the bottom edge of the last view is from the bottom of the 1241 // drawable area 1242 int bottomOffset = end - lastBottom; 1243 View firstChild = getChildAt(0); 1244 final int firstTop = firstChild.getTop(); 1245 1246 // Make sure we are 1) Too high, and 2) Either there are more rows above the 1247 // first row or the first row is scrolled off the top of the drawable area 1248 if (bottomOffset > 0 && (mFirstPosition > 0 || firstTop < mListPadding.top)) { 1249 if (mFirstPosition == 0) { 1250 // Don't pull the top too far down 1251 bottomOffset = Math.min(bottomOffset, mListPadding.top - firstTop); 1252 } 1253 // Move everything down 1254 offsetChildrenTopAndBottom(bottomOffset); 1255 if (mFirstPosition > 0) { 1256 // Fill the gap that was opened above mFirstPosition with more rows, if 1257 // possible 1258 fillUp(mFirstPosition - 1, firstChild.getTop() - mDividerHeight); 1259 // Close up the remaining gap 1260 adjustViewsUpOrDown(); 1261 } 1262 1263 } 1264 } 1265 } 1266 1267 /** 1268 * Check if we have dragged the bottom of the list too low (we have pushed the 1269 * bottom element off the bottom of the screen when we did not need to). Correct by sliding 1270 * everything back up. 1271 * 1272 * @param childCount Number of children 1273 */ 1274 private void correctTooLow(int childCount) { 1275 // First see if the first item is visible. If it is not, it is OK for the 1276 // bottom of the list to be pushed down. 1277 if (mFirstPosition == 0 && childCount > 0) { 1278 1279 // Get the first child ... 1280 final View firstChild = getChildAt(0); 1281 1282 // ... and its top edge 1283 final int firstTop = firstChild.getTop(); 1284 1285 // This is top of our drawable area 1286 final int start = mListPadding.top; 1287 1288 // This is bottom of our drawable area 1289 final int end = (mBottom - mTop) - mListPadding.bottom; 1290 1291 // This is how far the top edge of the first view is from the top of the 1292 // drawable area 1293 int topOffset = firstTop - start; 1294 View lastChild = getChildAt(childCount - 1); 1295 final int lastBottom = lastChild.getBottom(); 1296 int lastPosition = mFirstPosition + childCount - 1; 1297 1298 // Make sure we are 1) Too low, and 2) Either there are more rows below the 1299 // last row or the last row is scrolled off the bottom of the drawable area 1300 if (topOffset > 0 && (lastPosition < mItemCount - 1 || lastBottom > end)) { 1301 if (lastPosition == mItemCount - 1 ) { 1302 // Don't pull the bottom too far up 1303 topOffset = Math.min(topOffset, lastBottom - end); 1304 } 1305 // Move everything up 1306 offsetChildrenTopAndBottom(-topOffset); 1307 if (lastPosition < mItemCount - 1) { 1308 // Fill the gap that was opened below the last position with more rows, if 1309 // possible 1310 fillDown(lastPosition + 1, lastChild.getBottom() + mDividerHeight); 1311 // Close up the remaining gap 1312 adjustViewsUpOrDown(); 1313 } 1314 } 1315 } 1316 } 1317 1318 @Override 1319 protected void layoutChildren() { 1320 final boolean blockLayoutRequests = mBlockLayoutRequests; 1321 if (!blockLayoutRequests) { 1322 mBlockLayoutRequests = true; 1323 } else { 1324 return; 1325 } 1326 1327 try { 1328 super.layoutChildren(); 1329 1330 invalidate(); 1331 1332 if (mAdapter == null) { 1333 resetList(); 1334 invokeOnItemScrollListener(); 1335 return; 1336 } 1337 1338 int childrenTop = mListPadding.top; 1339 int childrenBottom = mBottom - mTop - mListPadding.bottom; 1340 1341 int childCount = getChildCount(); 1342 int index; 1343 int delta = 0; 1344 1345 View sel; 1346 View oldSel = null; 1347 View oldFirst = null; 1348 View newSel = null; 1349 1350 View focusLayoutRestoreView = null; 1351 1352 // Remember stuff we will need down below 1353 switch (mLayoutMode) { 1354 case LAYOUT_SET_SELECTION: 1355 index = mNextSelectedPosition - mFirstPosition; 1356 if (index >= 0 && index < childCount) { 1357 newSel = getChildAt(index); 1358 } 1359 break; 1360 case LAYOUT_FORCE_TOP: 1361 case LAYOUT_FORCE_BOTTOM: 1362 case LAYOUT_SPECIFIC: 1363 case LAYOUT_SYNC: 1364 break; 1365 case LAYOUT_MOVE_SELECTION: 1366 default: 1367 // Remember the previously selected view 1368 index = mSelectedPosition - mFirstPosition; 1369 if (index >= 0 && index < childCount) { 1370 oldSel = getChildAt(index); 1371 } 1372 1373 // Remember the previous first child 1374 oldFirst = getChildAt(0); 1375 1376 if (mNextSelectedPosition >= 0) { 1377 delta = mNextSelectedPosition - mSelectedPosition; 1378 } 1379 1380 // Caution: newSel might be null 1381 newSel = getChildAt(index + delta); 1382 } 1383 1384 1385 boolean dataChanged = mDataChanged; 1386 if (dataChanged) { 1387 handleDataChanged(); 1388 } 1389 1390 // Handle the empty set by removing all views that are visible 1391 // and calling it a day 1392 if (mItemCount == 0) { 1393 resetList(); 1394 invokeOnItemScrollListener(); 1395 return; 1396 } 1397 1398 setSelectedPositionInt(mNextSelectedPosition); 1399 1400 // Pull all children into the RecycleBin. 1401 // These views will be reused if possible 1402 final int firstPosition = mFirstPosition; 1403 final RecycleBin recycleBin = mRecycler; 1404 1405 // reset the focus restoration 1406 View focusLayoutRestoreDirectChild = null; 1407 1408 1409 // Don't put header or footer views into the Recycler. Those are 1410 // already cached in mHeaderViews; 1411 if (dataChanged) { 1412 for (int i = 0; i < childCount; i++) { 1413 recycleBin.addScrapView(getChildAt(i)); 1414 if (ViewDebug.TRACE_RECYCLER) { 1415 ViewDebug.trace(getChildAt(i), 1416 ViewDebug.RecyclerTraceType.MOVE_TO_SCRAP_HEAP, index, i); 1417 } 1418 } 1419 } else { 1420 recycleBin.fillActiveViews(childCount, firstPosition); 1421 } 1422 1423 // take focus back to us temporarily to avoid the eventual 1424 // call to clear focus when removing the focused child below 1425 // from messing things up when ViewRoot assigns focus back 1426 // to someone else 1427 final View focusedChild = getFocusedChild(); 1428 if (focusedChild != null) { 1429 // TODO: in some cases focusedChild.getParent() == null 1430 1431 // we can remember the focused view to restore after relayout if the 1432 // data hasn't changed, or if the focused position is a header or footer 1433 if (!dataChanged || isDirectChildHeaderOrFooter(focusedChild)) { 1434 focusLayoutRestoreDirectChild = focusedChild; 1435 // remember the specific view that had focus 1436 focusLayoutRestoreView = findFocus(); 1437 if (focusLayoutRestoreView != null) { 1438 // tell it we are going to mess with it 1439 focusLayoutRestoreView.onStartTemporaryDetach(); 1440 } 1441 } 1442 requestFocus(); 1443 } 1444 1445 // Clear out old views 1446 //removeAllViewsInLayout(); 1447 detachAllViewsFromParent(); 1448 1449 switch (mLayoutMode) { 1450 case LAYOUT_SET_SELECTION: 1451 if (newSel != null) { 1452 sel = fillFromSelection(newSel.getTop(), childrenTop, childrenBottom); 1453 } else { 1454 sel = fillFromMiddle(childrenTop, childrenBottom); 1455 } 1456 break; 1457 case LAYOUT_SYNC: 1458 sel = fillSpecific(mSyncPosition, mSpecificTop); 1459 break; 1460 case LAYOUT_FORCE_BOTTOM: 1461 sel = fillUp(mItemCount - 1, childrenBottom); 1462 adjustViewsUpOrDown(); 1463 break; 1464 case LAYOUT_FORCE_TOP: 1465 mFirstPosition = 0; 1466 sel = fillFromTop(childrenTop); 1467 adjustViewsUpOrDown(); 1468 break; 1469 case LAYOUT_SPECIFIC: 1470 sel = fillSpecific(reconcileSelectedPosition(), mSpecificTop); 1471 break; 1472 case LAYOUT_MOVE_SELECTION: 1473 sel = moveSelection(oldSel, newSel, delta, childrenTop, childrenBottom); 1474 break; 1475 default: 1476 if (childCount == 0) { 1477 if (!mStackFromBottom) { 1478 final int position = lookForSelectablePosition(0, true); 1479 setSelectedPositionInt(position); 1480 sel = fillFromTop(childrenTop); 1481 } else { 1482 final int position = lookForSelectablePosition(mItemCount - 1, false); 1483 setSelectedPositionInt(position); 1484 sel = fillUp(mItemCount - 1, childrenBottom); 1485 } 1486 } else { 1487 if (mSelectedPosition >= 0 && mSelectedPosition < mItemCount) { 1488 sel = fillSpecific(mSelectedPosition, 1489 oldSel == null ? childrenTop : oldSel.getTop()); 1490 } else if (mFirstPosition < mItemCount) { 1491 sel = fillSpecific(mFirstPosition, 1492 oldFirst == null ? childrenTop : oldFirst.getTop()); 1493 } else { 1494 sel = fillSpecific(0, childrenTop); 1495 } 1496 } 1497 break; 1498 } 1499 1500 // Flush any cached views that did not get reused above 1501 recycleBin.scrapActiveViews(); 1502 1503 if (sel != null) { 1504 // the current selected item should get focus if items 1505 // are focusable 1506 if (mItemsCanFocus && hasFocus() && !sel.hasFocus()) { 1507 final boolean focusWasTaken = (sel == focusLayoutRestoreDirectChild && 1508 focusLayoutRestoreView.requestFocus()) || sel.requestFocus(); 1509 if (!focusWasTaken) { 1510 // selected item didn't take focus, fine, but still want 1511 // to make sure something else outside of the selected view 1512 // has focus 1513 final View focused = getFocusedChild(); 1514 if (focused != null) { 1515 focused.clearFocus(); 1516 } 1517 positionSelector(sel); 1518 } else { 1519 sel.setSelected(false); 1520 mSelectorRect.setEmpty(); 1521 } 1522 } else { 1523 positionSelector(sel); 1524 } 1525 mSelectedTop = sel.getTop(); 1526 } else { 1527 mSelectedTop = 0; 1528 mSelectorRect.setEmpty(); 1529 1530 // even if there is not selected position, we may need to restore 1531 // focus (i.e. something focusable in touch mode) 1532 if (hasFocus() && focusLayoutRestoreView != null) { 1533 focusLayoutRestoreView.requestFocus(); 1534 } 1535 } 1536 1537 // tell focus view we are done mucking with it, if it is still in 1538 // our view hierarchy. 1539 if (focusLayoutRestoreView != null 1540 && focusLayoutRestoreView.getWindowToken() != null) { 1541 focusLayoutRestoreView.onFinishTemporaryDetach(); 1542 } 1543 1544 mLayoutMode = LAYOUT_NORMAL; 1545 mDataChanged = false; 1546 mNeedSync = false; 1547 setNextSelectedPositionInt(mSelectedPosition); 1548 1549 updateScrollIndicators(); 1550 1551 if (mItemCount > 0) { 1552 checkSelectionChanged(); 1553 } 1554 1555 invokeOnItemScrollListener(); 1556 } finally { 1557 if (!blockLayoutRequests) { 1558 mBlockLayoutRequests = false; 1559 } 1560 } 1561 } 1562 1563 /** 1564 * @param child a direct child of this list. 1565 * @return Whether child is a header or footer view. 1566 */ 1567 private boolean isDirectChildHeaderOrFooter(View child) { 1568 1569 final ArrayList<FixedViewInfo> headers = mHeaderViewInfos; 1570 final int numHeaders = headers.size(); 1571 for (int i = 0; i < numHeaders; i++) { 1572 if (child == headers.get(i).view) { 1573 return true; 1574 } 1575 } 1576 final ArrayList<FixedViewInfo> footers = mFooterViewInfos; 1577 final int numFooters = footers.size(); 1578 for (int i = 0; i < numFooters; i++) { 1579 if (child == footers.get(i).view) { 1580 return true; 1581 } 1582 } 1583 return false; 1584 } 1585 1586 /** 1587 * Obtain the view and add it to our list of children. The view can be made 1588 * fresh, converted from an unused view, or used as is if it was in the 1589 * recycle bin. 1590 * 1591 * @param position Logical position in the list 1592 * @param y Top or bottom edge of the view to add 1593 * @param flow If flow is true, align top edge to y. If false, align bottom 1594 * edge to y. 1595 * @param childrenLeft Left edge where children should be positioned 1596 * @param selected Is this position selected? 1597 * @return View that was added 1598 */ 1599 private View makeAndAddView(int position, int y, boolean flow, int childrenLeft, 1600 boolean selected) { 1601 View child; 1602 1603 1604 if (!mDataChanged) { 1605 // Try to use an exsiting view for this position 1606 child = mRecycler.getActiveView(position); 1607 if (child != null) { 1608 if (ViewDebug.TRACE_RECYCLER) { 1609 ViewDebug.trace(child, ViewDebug.RecyclerTraceType.RECYCLE_FROM_ACTIVE_HEAP, 1610 position, getChildCount()); 1611 } 1612 1613 // Found it -- we're using an existing child 1614 // This just needs to be positioned 1615 setupChild(child, position, y, flow, childrenLeft, selected, true); 1616 1617 return child; 1618 } 1619 } 1620 1621 // Make a new view for this position, or convert an unused view if possible 1622 child = obtainView(position); 1623 1624 // This needs to be positioned and measured 1625 setupChild(child, position, y, flow, childrenLeft, selected, false); 1626 1627 return child; 1628 } 1629 1630 /** 1631 * Add a view as a child and make sure it is measured (if necessary) and 1632 * positioned properly. 1633 * 1634 * @param child The view to add 1635 * @param position The position of this child 1636 * @param y The y position relative to which this view will be positioned 1637 * @param flowDown If true, align top edge to y. If false, align bottom 1638 * edge to y. 1639 * @param childrenLeft Left edge where children should be positioned 1640 * @param selected Is this position selected? 1641 * @param recycled Has this view been pulled from the recycle bin? If so it 1642 * does not need to be remeasured. 1643 */ 1644 private void setupChild(View child, int position, int y, boolean flowDown, int childrenLeft, 1645 boolean selected, boolean recycled) { 1646 final boolean isSelected = selected && shouldShowSelector(); 1647 final boolean updateChildSelected = isSelected != child.isSelected(); 1648 final boolean needToMeasure = !recycled || updateChildSelected || child.isLayoutRequested(); 1649 1650 // Respect layout params that are already in the view. Otherwise make some up... 1651 // noinspection unchecked 1652 AbsListView.LayoutParams p = (AbsListView.LayoutParams) child.getLayoutParams(); 1653 if (p == null) { 1654 p = new AbsListView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, 1655 ViewGroup.LayoutParams.WRAP_CONTENT, 0); 1656 } 1657 p.viewType = mAdapter.getItemViewType(position); 1658 1659 if (recycled || (p.recycledHeaderFooter && p.viewType == AdapterView.ITEM_VIEW_TYPE_HEADER_OR_FOOTER)) { 1660 attachViewToParent(child, flowDown ? -1 : 0, p); 1661 } else { 1662 if (p.viewType == AdapterView.ITEM_VIEW_TYPE_HEADER_OR_FOOTER) { 1663 p.recycledHeaderFooter = true; 1664 } 1665 addViewInLayout(child, flowDown ? -1 : 0, p, true); 1666 } 1667 1668 if (updateChildSelected) { 1669 child.setSelected(isSelected); 1670 } 1671 1672 if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates != null) { 1673 if (child instanceof Checkable) { 1674 ((Checkable) child).setChecked(mCheckStates.get(position)); 1675 } 1676 } 1677 1678 if (needToMeasure) { 1679 int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec, 1680 mListPadding.left + mListPadding.right, p.width); 1681 int lpHeight = p.height; 1682 int childHeightSpec; 1683 if (lpHeight > 0) { 1684 childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY); 1685 } else { 1686 childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1687 } 1688 child.measure(childWidthSpec, childHeightSpec); 1689 } else { 1690 cleanupLayoutState(child); 1691 } 1692 1693 final int w = child.getMeasuredWidth(); 1694 final int h = child.getMeasuredHeight(); 1695 final int childTop = flowDown ? y : y - h; 1696 1697 if (needToMeasure) { 1698 final int childRight = childrenLeft + w; 1699 final int childBottom = childTop + h; 1700 child.layout(childrenLeft, childTop, childRight, childBottom); 1701 } else { 1702 child.offsetLeftAndRight(childrenLeft - child.getLeft()); 1703 child.offsetTopAndBottom(childTop - child.getTop()); 1704 } 1705 1706 if (mCachingStarted && !child.isDrawingCacheEnabled()) { 1707 child.setDrawingCacheEnabled(true); 1708 } 1709 } 1710 1711 @Override 1712 protected boolean canAnimate() { 1713 return super.canAnimate() && mItemCount > 0; 1714 } 1715 1716 /** 1717 * Sets the currently selected item. If in touch mode, the item will not be selected 1718 * but it will still be positioned appropriately. If the specified selection position 1719 * is less than 0, then the item at position 0 will be selected. 1720 * 1721 * @param position Index (starting at 0) of the data item to be selected. 1722 */ 1723 @Override 1724 public void setSelection(int position) { 1725 setSelectionFromTop(position, 0); 1726 } 1727 1728 /** 1729 * Sets the selected item and positions the selection y pixels from the top edge 1730 * of the ListView. (If in touch mode, the item will not be selected but it will 1731 * still be positioned appropriately.) 1732 * 1733 * @param position Index (starting at 0) of the data item to be selected. 1734 * @param y The distance from the top edge of the ListView (plus padding) that the 1735 * item will be positioned. 1736 */ 1737 public void setSelectionFromTop(int position, int y) { 1738 if (mAdapter == null) { 1739 return; 1740 } 1741 1742 if (!isInTouchMode()) { 1743 position = lookForSelectablePosition(position, true); 1744 if (position >= 0) { 1745 setNextSelectedPositionInt(position); 1746 } 1747 } else { 1748 mResurrectToPosition = position; 1749 } 1750 1751 if (position >= 0) { 1752 mLayoutMode = LAYOUT_SPECIFIC; 1753 mSpecificTop = mListPadding.top + y; 1754 1755 if (mNeedSync) { 1756 mSyncPosition = position; 1757 mSyncRowId = mAdapter.getItemId(position); 1758 } 1759 1760 requestLayout(); 1761 } 1762 } 1763 1764 /** 1765 * Makes the item at the supplied position selected. 1766 * 1767 * @param position the position of the item to select 1768 */ 1769 @Override 1770 void setSelectionInt(int position) { 1771 setNextSelectedPositionInt(position); 1772 layoutChildren(); 1773 } 1774 1775 /** 1776 * Find a position that can be selected (i.e., is not a separator). 1777 * 1778 * @param position The starting position to look at. 1779 * @param lookDown Whether to look down for other positions. 1780 * @return The next selectable position starting at position and then searching either up or 1781 * down. Returns {@link #INVALID_POSITION} if nothing can be found. 1782 */ 1783 @Override 1784 int lookForSelectablePosition(int position, boolean lookDown) { 1785 final ListAdapter adapter = mAdapter; 1786 if (adapter == null || isInTouchMode()) { 1787 return INVALID_POSITION; 1788 } 1789 1790 final int count = adapter.getCount(); 1791 if (!mAreAllItemsSelectable) { 1792 if (lookDown) { 1793 position = Math.max(0, position); 1794 while (position < count && !adapter.isEnabled(position)) { 1795 position++; 1796 } 1797 } else { 1798 position = Math.min(position, count - 1); 1799 while (position >= 0 && !adapter.isEnabled(position)) { 1800 position--; 1801 } 1802 } 1803 1804 if (position < 0 || position >= count) { 1805 return INVALID_POSITION; 1806 } 1807 return position; 1808 } else { 1809 if (position < 0 || position >= count) { 1810 return INVALID_POSITION; 1811 } 1812 return position; 1813 } 1814 } 1815 1816 /** 1817 * setSelectionAfterHeaderView set the selection to be the first list item 1818 * after the header views. 1819 */ 1820 public void setSelectionAfterHeaderView() { 1821 final int count = mHeaderViewInfos.size(); 1822 if (count > 0) { 1823 mNextSelectedPosition = 0; 1824 return; 1825 } 1826 1827 if (mAdapter != null) { 1828 setSelection(count); 1829 } else { 1830 mNextSelectedPosition = count; 1831 mLayoutMode = LAYOUT_SET_SELECTION; 1832 } 1833 1834 } 1835 1836 @Override 1837 public boolean dispatchKeyEvent(KeyEvent event) { 1838 // Dispatch in the normal way 1839 boolean handled = super.dispatchKeyEvent(event); 1840 if (!handled) { 1841 // If we didn't handle it... 1842 View focused = getFocusedChild(); 1843 if (focused != null && event.getAction() == KeyEvent.ACTION_DOWN) { 1844 // ... and our focused child didn't handle it 1845 // ... give it to ourselves so we can scroll if necessary 1846 handled = onKeyDown(event.getKeyCode(), event); 1847 } 1848 } 1849 return handled; 1850 } 1851 1852 @Override 1853 public boolean onKeyDown(int keyCode, KeyEvent event) { 1854 return commonKey(keyCode, 1, event); 1855 } 1856 1857 @Override 1858 public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event) { 1859 return commonKey(keyCode, repeatCount, event); 1860 } 1861 1862 @Override 1863 public boolean onKeyUp(int keyCode, KeyEvent event) { 1864 return commonKey(keyCode, 1, event); 1865 } 1866 1867 private boolean commonKey(int keyCode, int count, KeyEvent event) { 1868 if (mAdapter == null) { 1869 return false; 1870 } 1871 1872 if (mDataChanged) { 1873 layoutChildren(); 1874 } 1875 1876 boolean handled = false; 1877 int action = event.getAction(); 1878 1879 if (action != KeyEvent.ACTION_UP) { 1880 if (mSelectedPosition < 0) { 1881 switch (keyCode) { 1882 case KeyEvent.KEYCODE_DPAD_UP: 1883 case KeyEvent.KEYCODE_DPAD_DOWN: 1884 case KeyEvent.KEYCODE_DPAD_CENTER: 1885 case KeyEvent.KEYCODE_ENTER: 1886 case KeyEvent.KEYCODE_SPACE: 1887 if (resurrectSelection()) { 1888 return true; 1889 } 1890 } 1891 } 1892 switch (keyCode) { 1893 case KeyEvent.KEYCODE_DPAD_UP: 1894 if (!event.isAltPressed()) { 1895 while (count > 0) { 1896 handled = arrowScroll(FOCUS_UP); 1897 count--; 1898 } 1899 } else { 1900 handled = fullScroll(FOCUS_UP); 1901 } 1902 break; 1903 1904 case KeyEvent.KEYCODE_DPAD_DOWN: 1905 if (!event.isAltPressed()) { 1906 while (count > 0) { 1907 handled = arrowScroll(FOCUS_DOWN); 1908 count--; 1909 } 1910 } else { 1911 handled = fullScroll(FOCUS_DOWN); 1912 } 1913 break; 1914 1915 case KeyEvent.KEYCODE_DPAD_LEFT: 1916 handled = handleHorizontalFocusWithinListItem(View.FOCUS_LEFT); 1917 break; 1918 case KeyEvent.KEYCODE_DPAD_RIGHT: 1919 handled = handleHorizontalFocusWithinListItem(View.FOCUS_RIGHT); 1920 break; 1921 1922 case KeyEvent.KEYCODE_DPAD_CENTER: 1923 case KeyEvent.KEYCODE_ENTER: 1924 if (mItemCount > 0 && event.getRepeatCount() == 0) { 1925 keyPressed(); 1926 } 1927 handled = true; 1928 break; 1929 1930 case KeyEvent.KEYCODE_SPACE: 1931 if (mPopup == null || !mPopup.isShowing()) { 1932 if (!event.isShiftPressed()) { 1933 pageScroll(FOCUS_DOWN); 1934 } else { 1935 pageScroll(FOCUS_UP); 1936 } 1937 handled = true; 1938 } 1939 break; 1940 } 1941 } 1942 1943 if (!handled) { 1944 handled = sendToTextFilter(keyCode, count, event); 1945 } 1946 1947 if (handled) { 1948 return true; 1949 } else { 1950 switch (action) { 1951 case KeyEvent.ACTION_DOWN: 1952 return super.onKeyDown(keyCode, event); 1953 1954 case KeyEvent.ACTION_UP: 1955 return super.onKeyUp(keyCode, event); 1956 1957 case KeyEvent.ACTION_MULTIPLE: 1958 return super.onKeyMultiple(keyCode, count, event); 1959 1960 default: // shouldn't happen 1961 return false; 1962 } 1963 } 1964 } 1965 1966 /** 1967 * Scrolls up or down by the number of items currently present on screen. 1968 * 1969 * @param direction either {@link View#FOCUS_UP} or {@link View#FOCUS_DOWN} 1970 * @return whether selection was moved 1971 */ 1972 boolean pageScroll(int direction) { 1973 int nextPage = -1; 1974 boolean down = false; 1975 1976 if (direction == FOCUS_UP) { 1977 nextPage = Math.max(0, mSelectedPosition - getChildCount() - 1); 1978 } else if (direction == FOCUS_DOWN) { 1979 nextPage = Math.min(mItemCount - 1, mSelectedPosition + getChildCount() - 1); 1980 down = true; 1981 } 1982 1983 if (nextPage >= 0) { 1984 int position = lookForSelectablePosition(nextPage, down); 1985 if (position >= 0) { 1986 mLayoutMode = LAYOUT_SPECIFIC; 1987 mSpecificTop = mPaddingTop + getVerticalFadingEdgeLength(); 1988 1989 if (down && position > mItemCount - getChildCount()) { 1990 mLayoutMode = LAYOUT_FORCE_BOTTOM; 1991 } 1992 1993 if (!down && position < getChildCount()) { 1994 mLayoutMode = LAYOUT_FORCE_TOP; 1995 } 1996 1997 setSelectionInt(position); 1998 invokeOnItemScrollListener(); 1999 invalidate(); 2000 2001 return true; 2002 } 2003 } 2004 2005 return false; 2006 } 2007 2008 /** 2009 * Go to the last or first item if possible (not worrying about panning across or navigating 2010 * within the internal focus of the currently selected item.) 2011 * 2012 * @param direction either {@link View#FOCUS_UP} or {@link View#FOCUS_DOWN} 2013 * 2014 * @return whether selection was moved 2015 */ 2016 boolean fullScroll(int direction) { 2017 boolean moved = false; 2018 if (direction == FOCUS_UP) { 2019 if (mSelectedPosition != 0) { 2020 int position = lookForSelectablePosition(0, true); 2021 if (position >= 0) { 2022 mLayoutMode = LAYOUT_FORCE_TOP; 2023 setSelectionInt(position); 2024 invokeOnItemScrollListener(); 2025 } 2026 moved = true; 2027 } 2028 } else if (direction == FOCUS_DOWN) { 2029 if (mSelectedPosition < mItemCount - 1) { 2030 int position = lookForSelectablePosition(mItemCount - 1, true); 2031 if (position >= 0) { 2032 mLayoutMode = LAYOUT_FORCE_BOTTOM; 2033 setSelectionInt(position); 2034 invokeOnItemScrollListener(); 2035 } 2036 moved = true; 2037 } 2038 } 2039 2040 if (moved) { 2041 invalidate(); 2042 } 2043 2044 return moved; 2045 } 2046 2047 /** 2048 * To avoid horizontal focus searches changing the selected item, we 2049 * manually focus search within the selected item (as applicable), and 2050 * prevent focus from jumping to something within another item. 2051 * @param direction one of {View.FOCUS_LEFT, View.FOCUS_RIGHT} 2052 * @return Whether this consumes the key event. 2053 */ 2054 private boolean handleHorizontalFocusWithinListItem(int direction) { 2055 if (direction != View.FOCUS_LEFT && direction != View.FOCUS_RIGHT) { 2056 throw new IllegalArgumentException("direction must be one of {View.FOCUS_LEFT, View.FOCUS_RIGHT}"); 2057 } 2058 2059 final int numChildren = getChildCount(); 2060 if (mItemsCanFocus && numChildren > 0 && mSelectedPosition != INVALID_POSITION) { 2061 final View selectedView = getSelectedView(); 2062 if (selectedView.hasFocus() && selectedView instanceof ViewGroup) { 2063 final View currentFocus = selectedView.findFocus(); 2064 final View nextFocus = FocusFinder.getInstance().findNextFocus( 2065 (ViewGroup) selectedView, 2066 currentFocus, 2067 direction); 2068 if (nextFocus != null) { 2069 // do the math to get interesting rect in next focus' coordinates 2070 currentFocus.getFocusedRect(mTempRect); 2071 offsetDescendantRectToMyCoords(currentFocus, mTempRect); 2072 offsetRectIntoDescendantCoords(nextFocus, mTempRect); 2073 if (nextFocus.requestFocus(direction, mTempRect)) { 2074 return true; 2075 } 2076 } 2077 // we are blocking the key from being handled (by returning true) 2078 // if the global result is going to be some other view within this 2079 // list. this is to acheive the overall goal of having 2080 // horizontal d-pad navigation remain in the current item. 2081 final View globalNextFocus = FocusFinder.getInstance() 2082 .findNextFocus( 2083 (ViewGroup) getRootView(), 2084 currentFocus, 2085 direction); 2086 if (globalNextFocus != null) { 2087 return isViewAncestorOf(globalNextFocus, this); 2088 } 2089 } 2090 } 2091 return false; 2092 } 2093 2094 /** 2095 * Scrolls to the next or previous item if possible. 2096 * 2097 * @param direction either {@link View#FOCUS_UP} or {@link View#FOCUS_DOWN} 2098 * 2099 * @return whether selection was moved 2100 */ 2101 boolean arrowScroll(int direction) { 2102 try { 2103 mInLayout = true; 2104 final boolean handled = arrowScrollImpl(direction); 2105 if (handled) { 2106 playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction)); 2107 } 2108 return handled; 2109 } finally { 2110 mInLayout = false; 2111 } 2112 } 2113 2114 /** 2115 * Handle an arrow scroll going up or down. Take into account whether items are selectable, 2116 * whether there are focusable items etc. 2117 * 2118 * @param direction Either {@link android.view.View#FOCUS_UP} or {@link android.view.View#FOCUS_DOWN}. 2119 * @return Whether any scrolling, selection or focus change occured. 2120 */ 2121 private boolean arrowScrollImpl(int direction) { 2122 if (getChildCount() <= 0) { 2123 return false; 2124 } 2125 2126 View selectedView = getSelectedView(); 2127 2128 int nextSelectedPosition = lookForSelectablePositionOnScreen(direction); 2129 int amountToScroll = amountToScroll(direction, nextSelectedPosition); 2130 2131 // if we are moving focus, we may OVERRIDE the default behavior 2132 final ArrowScrollFocusResult focusResult = mItemsCanFocus ? arrowScrollFocused(direction) : null; 2133 if (focusResult != null) { 2134 nextSelectedPosition = focusResult.getSelectedPosition(); 2135 amountToScroll = focusResult.getAmountToScroll(); 2136 } 2137 2138 boolean needToRedraw = focusResult != null; 2139 if (nextSelectedPosition != INVALID_POSITION) { 2140 handleNewSelectionChange(selectedView, direction, nextSelectedPosition, focusResult != null); 2141 setSelectedPositionInt(nextSelectedPosition); 2142 setNextSelectedPositionInt(nextSelectedPosition); 2143 selectedView = getSelectedView(); 2144 if (mItemsCanFocus && focusResult == null) { 2145 // there was no new view found to take focus, make sure we 2146 // don't leave focus with the old selection 2147 final View focused = getFocusedChild(); 2148 if (focused != null) { 2149 focused.clearFocus(); 2150 } 2151 } 2152 needToRedraw = true; 2153 checkSelectionChanged(); 2154 } 2155 2156 if (amountToScroll > 0) { 2157 scrollListItemsBy((direction == View.FOCUS_UP) ? amountToScroll : -amountToScroll); 2158 needToRedraw = true; 2159 } 2160 2161 // if we didn't find a new focusable, make sure any existing focused 2162 // item that was panned off screen gives up focus. 2163 if (mItemsCanFocus && (focusResult == null) 2164 && selectedView != null && selectedView.hasFocus()) { 2165 final View focused = selectedView.findFocus(); 2166 if (distanceToView(focused) > 0) { 2167 focused.clearFocus(); 2168 } 2169 } 2170 2171 // if the current selection is panned off, we need to remove the selection 2172 if (nextSelectedPosition == INVALID_POSITION && selectedView != null 2173 && !isViewAncestorOf(selectedView, this)) { 2174 selectedView = null; 2175 hideSelector(); 2176 2177 // but we don't want to set the ressurect position (that would make subsequent 2178 // unhandled key events bring back the item we just scrolled off!) 2179 mResurrectToPosition = INVALID_POSITION; 2180 } 2181 2182 if (needToRedraw) { 2183 if (selectedView != null) { 2184 positionSelector(selectedView); 2185 mSelectedTop = selectedView.getTop(); 2186 } 2187 invalidate(); 2188 invokeOnItemScrollListener(); 2189 return true; 2190 } 2191 2192 return false; 2193 } 2194 2195 /** 2196 * When selection changes, it is possible that the previously selected or the 2197 * next selected item will change its size. If so, we need to offset some folks, 2198 * and re-layout the items as appropriate. 2199 * 2200 * @param selectedView The currently selected view (before changing selection). 2201 * should be <code>null</code> if there was no previous selection. 2202 * @param direction Either {@link android.view.View#FOCUS_UP} or 2203 * {@link android.view.View#FOCUS_DOWN}. 2204 * @param newSelectedPosition The position of the next selection. 2205 * @param newFocusAssigned whether new focus was assigned. This matters because 2206 * when something has focus, we don't want to show selection (ugh). 2207 */ 2208 private void handleNewSelectionChange(View selectedView, int direction, int newSelectedPosition, 2209 boolean newFocusAssigned) { 2210 if (newSelectedPosition == INVALID_POSITION) { 2211 throw new IllegalArgumentException("newSelectedPosition needs to be valid"); 2212 } 2213 2214 // whether or not we are moving down or up, we want to preserve the 2215 // top of whatever view is on top: 2216 // - moving down: the view that had selection 2217 // - moving up: the view that is getting selection 2218 View topView; 2219 View bottomView; 2220 int topViewIndex, bottomViewIndex; 2221 boolean topSelected = false; 2222 final int selectedIndex = mSelectedPosition - mFirstPosition; 2223 final int nextSelectedIndex = newSelectedPosition - mFirstPosition; 2224 if (direction == View.FOCUS_UP) { 2225 topViewIndex = nextSelectedIndex; 2226 bottomViewIndex = selectedIndex; 2227 topView = getChildAt(topViewIndex); 2228 bottomView = selectedView; 2229 topSelected = true; 2230 } else { 2231 topViewIndex = selectedIndex; 2232 bottomViewIndex = nextSelectedIndex; 2233 topView = selectedView; 2234 bottomView = getChildAt(bottomViewIndex); 2235 } 2236 2237 final int numChildren = getChildCount(); 2238 2239 // start with top view: is it changing size? 2240 if (topView != null) { 2241 topView.setSelected(!newFocusAssigned && topSelected); 2242 measureAndAdjustDown(topView, topViewIndex, numChildren); 2243 } 2244 2245 // is the bottom view changing size? 2246 if (bottomView != null) { 2247 bottomView.setSelected(!newFocusAssigned && !topSelected); 2248 measureAndAdjustDown(bottomView, bottomViewIndex, numChildren); 2249 } 2250 } 2251 2252 /** 2253 * Re-measure a child, and if its height changes, lay it out preserving its 2254 * top, and adjust the children below it appropriately. 2255 * @param child The child 2256 * @param childIndex The view group index of the child. 2257 * @param numChildren The number of children in the view group. 2258 */ 2259 private void measureAndAdjustDown(View child, int childIndex, int numChildren) { 2260 int oldHeight = child.getHeight(); 2261 measureItem(child); 2262 if (child.getMeasuredHeight() != oldHeight) { 2263 // lay out the view, preserving its top 2264 relayoutMeasuredItem(child); 2265 2266 // adjust views below appropriately 2267 final int heightDelta = child.getMeasuredHeight() - oldHeight; 2268 for (int i = childIndex + 1; i < numChildren; i++) { 2269 getChildAt(i).offsetTopAndBottom(heightDelta); 2270 } 2271 } 2272 } 2273 2274 /** 2275 * Measure a particular list child. 2276 * TODO: unify with setUpChild. 2277 * @param child The child. 2278 */ 2279 private void measureItem(View child) { 2280 ViewGroup.LayoutParams p = child.getLayoutParams(); 2281 if (p == null) { 2282 p = new ViewGroup.LayoutParams( 2283 ViewGroup.LayoutParams.FILL_PARENT, 2284 ViewGroup.LayoutParams.WRAP_CONTENT); 2285 } 2286 2287 int childWidthSpec = ViewGroup.getChildMeasureSpec(mWidthMeasureSpec, 2288 mListPadding.left + mListPadding.right, p.width); 2289 int lpHeight = p.height; 2290 int childHeightSpec; 2291 if (lpHeight > 0) { 2292 childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY); 2293 } else { 2294 childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 2295 } 2296 child.measure(childWidthSpec, childHeightSpec); 2297 } 2298 2299 /** 2300 * Layout a child that has been measured, preserving its top position. 2301 * TODO: unify with setUpChild. 2302 * @param child The child. 2303 */ 2304 private void relayoutMeasuredItem(View child) { 2305 final int w = child.getMeasuredWidth(); 2306 final int h = child.getMeasuredHeight(); 2307 final int childLeft = mListPadding.left; 2308 final int childRight = childLeft + w; 2309 final int childTop = child.getTop(); 2310 final int childBottom = childTop + h; 2311 child.layout(childLeft, childTop, childRight, childBottom); 2312 } 2313 2314 /** 2315 * @return The amount to preview next items when arrow srolling. 2316 */ 2317 private int getArrowScrollPreviewLength() { 2318 return Math.max(MIN_SCROLL_PREVIEW_PIXELS, getVerticalFadingEdgeLength()); 2319 } 2320 2321 /** 2322 * Determine how much we need to scroll in order to get the next selected view 2323 * visible, with a fading edge showing below as applicable. The amount is 2324 * capped at {@link #getMaxScrollAmount()} . 2325 * 2326 * @param direction either {@link android.view.View#FOCUS_UP} or 2327 * {@link android.view.View#FOCUS_DOWN}. 2328 * @param nextSelectedPosition The position of the next selection, or 2329 * {@link #INVALID_POSITION} if there is no next selectable position 2330 * @return The amount to scroll. Note: this is always positive! Direction 2331 * needs to be taken into account when actually scrolling. 2332 */ 2333 private int amountToScroll(int direction, int nextSelectedPosition) { 2334 final int listBottom = getHeight() - mListPadding.bottom; 2335 final int listTop = mListPadding.top; 2336 2337 final int numChildren = getChildCount(); 2338 2339 if (direction == View.FOCUS_DOWN) { 2340 int indexToMakeVisible = numChildren - 1; 2341 if (nextSelectedPosition != INVALID_POSITION) { 2342 indexToMakeVisible = nextSelectedPosition - mFirstPosition; 2343 } 2344 2345 final int positionToMakeVisible = mFirstPosition + indexToMakeVisible; 2346 final View viewToMakeVisible = getChildAt(indexToMakeVisible); 2347 2348 int goalBottom = listBottom; 2349 if (positionToMakeVisible < mItemCount - 1) { 2350 goalBottom -= getArrowScrollPreviewLength(); 2351 } 2352 2353 if (viewToMakeVisible.getBottom() <= goalBottom) { 2354 // item is fully visible. 2355 return 0; 2356 } 2357 2358 if (nextSelectedPosition != INVALID_POSITION 2359 && (goalBottom - viewToMakeVisible.getTop()) >= getMaxScrollAmount()) { 2360 // item already has enough of it visible, changing selection is good enough 2361 return 0; 2362 } 2363 2364 int amountToScroll = (viewToMakeVisible.getBottom() - goalBottom); 2365 2366 if ((mFirstPosition + numChildren) == mItemCount) { 2367 // last is last in list -> make sure we don't scroll past it 2368 final int max = getChildAt(numChildren - 1).getBottom() - listBottom; 2369 amountToScroll = Math.min(amountToScroll, max); 2370 } 2371 2372 return Math.min(amountToScroll, getMaxScrollAmount()); 2373 } else { 2374 int indexToMakeVisible = 0; 2375 if (nextSelectedPosition != INVALID_POSITION) { 2376 indexToMakeVisible = nextSelectedPosition - mFirstPosition; 2377 } 2378 final int positionToMakeVisible = mFirstPosition + indexToMakeVisible; 2379 final View viewToMakeVisible = getChildAt(indexToMakeVisible); 2380 int goalTop = listTop; 2381 if (positionToMakeVisible > 0) { 2382 goalTop += getArrowScrollPreviewLength(); 2383 } 2384 if (viewToMakeVisible.getTop() >= goalTop) { 2385 // item is fully visible. 2386 return 0; 2387 } 2388 2389 if (nextSelectedPosition != INVALID_POSITION && 2390 (viewToMakeVisible.getBottom() - goalTop) >= getMaxScrollAmount()) { 2391 // item already has enough of it visible, changing selection is good enough 2392 return 0; 2393 } 2394 2395 int amountToScroll = (goalTop - viewToMakeVisible.getTop()); 2396 if (mFirstPosition == 0) { 2397 // first is first in list -> make sure we don't scroll past it 2398 final int max = listTop - getChildAt(0).getTop(); 2399 amountToScroll = Math.min(amountToScroll, max); 2400 } 2401 return Math.min(amountToScroll, getMaxScrollAmount()); 2402 } 2403 } 2404 2405 /** 2406 * Holds results of focus aware arrow scrolling. 2407 */ 2408 static private class ArrowScrollFocusResult { 2409 private int mSelectedPosition; 2410 private int mAmountToScroll; 2411 2412 /** 2413 * How {@link android.widget.ListView#arrowScrollFocused} returns its values. 2414 */ 2415 void populate(int selectedPosition, int amountToScroll) { 2416 mSelectedPosition = selectedPosition; 2417 mAmountToScroll = amountToScroll; 2418 } 2419 2420 public int getSelectedPosition() { 2421 return mSelectedPosition; 2422 } 2423 2424 public int getAmountToScroll() { 2425 return mAmountToScroll; 2426 } 2427 } 2428 2429 /** 2430 * @param direction either {@link android.view.View#FOCUS_UP} or 2431 * {@link android.view.View#FOCUS_DOWN}. 2432 * @return The position of the next selectable position of the views that 2433 * are currently visible, taking into account the fact that there might 2434 * be no selection. Returns {@link #INVALID_POSITION} if there is no 2435 * selectable view on screen in the given direction. 2436 */ 2437 private int lookForSelectablePositionOnScreen(int direction) { 2438 final int firstPosition = mFirstPosition; 2439 if (direction == View.FOCUS_DOWN) { 2440 int startPos = (mSelectedPosition != INVALID_POSITION) ? 2441 mSelectedPosition + 1 : 2442 firstPosition; 2443 if (startPos >= mAdapter.getCount()) { 2444 return INVALID_POSITION; 2445 } 2446 if (startPos < firstPosition) { 2447 startPos = firstPosition; 2448 } 2449 2450 final int lastVisiblePos = getLastVisiblePosition(); 2451 final ListAdapter adapter = getAdapter(); 2452 for (int pos = startPos; pos <= lastVisiblePos; pos++) { 2453 if (adapter.isEnabled(pos) 2454 && getChildAt(pos - firstPosition).getVisibility() == View.VISIBLE) { 2455 return pos; 2456 } 2457 } 2458 } else { 2459 int last = firstPosition + getChildCount() - 1; 2460 int startPos = (mSelectedPosition != INVALID_POSITION) ? 2461 mSelectedPosition - 1 : 2462 firstPosition + getChildCount() - 1; 2463 if (startPos < 0) { 2464 return INVALID_POSITION; 2465 } 2466 if (startPos > last) { 2467 startPos = last; 2468 } 2469 2470 final ListAdapter adapter = getAdapter(); 2471 for (int pos = startPos; pos >= firstPosition; pos--) { 2472 if (adapter.isEnabled(pos) 2473 && getChildAt(pos - firstPosition).getVisibility() == View.VISIBLE) { 2474 return pos; 2475 } 2476 } 2477 } 2478 return INVALID_POSITION; 2479 } 2480 2481 /** 2482 * Do an arrow scroll based on focus searching. If a new view is 2483 * given focus, return the selection delta and amount to scroll via 2484 * an {@link ArrowScrollFocusResult}, otherwise, return null. 2485 * 2486 * @param direction either {@link android.view.View#FOCUS_UP} or 2487 * {@link android.view.View#FOCUS_DOWN}. 2488 * @return The result if focus has changed, or <code>null</code>. 2489 */ 2490 private ArrowScrollFocusResult arrowScrollFocused(final int direction) { 2491 final View selectedView = getSelectedView(); 2492 View newFocus; 2493 if (selectedView != null && selectedView.hasFocus()) { 2494 View oldFocus = selectedView.findFocus(); 2495 newFocus = FocusFinder.getInstance().findNextFocus(this, oldFocus, direction); 2496 } else { 2497 if (direction == View.FOCUS_DOWN) { 2498 final boolean topFadingEdgeShowing = (mFirstPosition > 0); 2499 final int listTop = mListPadding.top + 2500 (topFadingEdgeShowing ? getArrowScrollPreviewLength() : 0); 2501 final int ySearchPoint = 2502 (selectedView != null && selectedView.getTop() > listTop) ? 2503 selectedView.getTop() : 2504 listTop; 2505 mTempRect.set(0, ySearchPoint, 0, ySearchPoint); 2506 } else { 2507 final boolean bottomFadingEdgeShowing = 2508 (mFirstPosition + getChildCount() - 1) < mItemCount; 2509 final int listBottom = getHeight() - mListPadding.bottom - 2510 (bottomFadingEdgeShowing ? getArrowScrollPreviewLength() : 0); 2511 final int ySearchPoint = 2512 (selectedView != null && selectedView.getBottom() < listBottom) ? 2513 selectedView.getBottom() : 2514 listBottom; 2515 mTempRect.set(0, ySearchPoint, 0, ySearchPoint); 2516 } 2517 newFocus = FocusFinder.getInstance().findNextFocusFromRect(this, mTempRect, direction); 2518 } 2519 2520 if (newFocus != null) { 2521 final int positionOfNewFocus = positionOfNewFocus(newFocus); 2522 2523 // if the focus change is in a different new position, make sure 2524 // we aren't jumping over another selectable position 2525 if (mSelectedPosition != INVALID_POSITION && positionOfNewFocus != mSelectedPosition) { 2526 final int selectablePosition = lookForSelectablePositionOnScreen(direction); 2527 if (selectablePosition != INVALID_POSITION && 2528 ((direction == View.FOCUS_DOWN && selectablePosition < positionOfNewFocus) || 2529 (direction == View.FOCUS_UP && selectablePosition > positionOfNewFocus))) { 2530 return null; 2531 } 2532 } 2533 2534 int focusScroll = amountToScrollToNewFocus(direction, newFocus, positionOfNewFocus); 2535 2536 final int maxScrollAmount = getMaxScrollAmount(); 2537 if (focusScroll < maxScrollAmount) { 2538 // not moving too far, safe to give next view focus 2539 newFocus.requestFocus(direction); 2540 mArrowScrollFocusResult.populate(positionOfNewFocus, focusScroll); 2541 return mArrowScrollFocusResult; 2542 } else if (distanceToView(newFocus) < maxScrollAmount){ 2543 // Case to consider: 2544 // too far to get entire next focusable on screen, but by going 2545 // max scroll amount, we are getting it at least partially in view, 2546 // so give it focus and scroll the max ammount. 2547 newFocus.requestFocus(direction); 2548 mArrowScrollFocusResult.populate(positionOfNewFocus, maxScrollAmount); 2549 return mArrowScrollFocusResult; 2550 } 2551 } 2552 return null; 2553 } 2554 2555 /** 2556 * @param newFocus The view that would have focus. 2557 * @return the position that contains newFocus 2558 */ 2559 private int positionOfNewFocus(View newFocus) { 2560 final int numChildren = getChildCount(); 2561 for (int i = 0; i < numChildren; i++) { 2562 final View child = getChildAt(i); 2563 if (isViewAncestorOf(newFocus, child)) { 2564 return mFirstPosition + i; 2565 } 2566 } 2567 throw new IllegalArgumentException("newFocus is not a child of any of the" 2568 + " children of the list!"); 2569 } 2570 2571 /** 2572 * Return true if child is an ancestor of parent, (or equal to the parent). 2573 */ 2574 private boolean isViewAncestorOf(View child, View parent) { 2575 if (child == parent) { 2576 return true; 2577 } 2578 2579 final ViewParent theParent = child.getParent(); 2580 return (theParent instanceof ViewGroup) && isViewAncestorOf((View) theParent, parent); 2581 } 2582 2583 /** 2584 * Determine how much we need to scroll in order to get newFocus in view. 2585 * @param direction either {@link android.view.View#FOCUS_UP} or 2586 * {@link android.view.View#FOCUS_DOWN}. 2587 * @param newFocus The view that would take focus. 2588 * @param positionOfNewFocus The position of the list item containing newFocus 2589 * @return The amount to scroll. Note: this is always positive! Direction 2590 * needs to be taken into account when actually scrolling. 2591 */ 2592 private int amountToScrollToNewFocus(int direction, View newFocus, int positionOfNewFocus) { 2593 int amountToScroll = 0; 2594 newFocus.getDrawingRect(mTempRect); 2595 offsetDescendantRectToMyCoords(newFocus, mTempRect); 2596 if (direction == View.FOCUS_UP) { 2597 if (mTempRect.top < mListPadding.top) { 2598 amountToScroll = mListPadding.top - mTempRect.top; 2599 if (positionOfNewFocus > 0) { 2600 amountToScroll += getArrowScrollPreviewLength(); 2601 } 2602 } 2603 } else { 2604 final int listBottom = getHeight() - mListPadding.bottom; 2605 if (mTempRect.bottom > listBottom) { 2606 amountToScroll = mTempRect.bottom - listBottom; 2607 if (positionOfNewFocus < mItemCount - 1) { 2608 amountToScroll += getArrowScrollPreviewLength(); 2609 } 2610 } 2611 } 2612 return amountToScroll; 2613 } 2614 2615 /** 2616 * Determine the distance to the nearest edge of a view in a particular 2617 * direciton. 2618 * @param descendant A descendant of this list. 2619 * @return The distance, or 0 if the nearest edge is already on screen. 2620 */ 2621 private int distanceToView(View descendant) { 2622 int distance = 0; 2623 descendant.getDrawingRect(mTempRect); 2624 offsetDescendantRectToMyCoords(descendant, mTempRect); 2625 final int listBottom = mBottom - mTop - mListPadding.bottom; 2626 if (mTempRect.bottom < mListPadding.top) { 2627 distance = mListPadding.top - mTempRect.bottom; 2628 } else if (mTempRect.top > listBottom) { 2629 distance = mTempRect.top - listBottom; 2630 } 2631 return distance; 2632 } 2633 2634 2635 /** 2636 * Scroll the children by amount, adding a view at the end and removing 2637 * views that fall off as necessary. 2638 * 2639 * @param amount The amount (positive or negative) to scroll. 2640 */ 2641 private void scrollListItemsBy(int amount) { 2642 offsetChildrenTopAndBottom(amount); 2643 2644 final int listBottom = getHeight() - mListPadding.bottom; 2645 final int listTop = mListPadding.top; 2646 2647 if (amount < 0) { 2648 // shifted items up 2649 2650 // may need to pan views into the bottom space 2651 int numChildren = getChildCount(); 2652 View last = getChildAt(numChildren - 1); 2653 while (last.getBottom() < listBottom) { 2654 final int lastVisiblePosition = mFirstPosition + numChildren - 1; 2655 if (lastVisiblePosition < mItemCount - 1) { 2656 last = addViewBelow(last, lastVisiblePosition); 2657 numChildren++; 2658 } else { 2659 break; 2660 } 2661 } 2662 2663 // may have brought in the last child of the list that is skinnier 2664 // than the fading edge, thereby leaving space at the end. need 2665 // to shift back 2666 if (last.getBottom() < listBottom) { 2667 offsetChildrenTopAndBottom(listBottom - last.getBottom()); 2668 } 2669 2670 // top views may be panned off screen 2671 View first = getChildAt(0); 2672 while (first.getBottom() < listTop) { 2673 removeViewInLayout(first); 2674 mRecycler.addScrapView(first); 2675 first = getChildAt(0); 2676 mFirstPosition++; 2677 } 2678 } else { 2679 // shifted items down 2680 View first = getChildAt(0); 2681 2682 // may need to pan views into top 2683 while ((first.getTop() > listTop) && (mFirstPosition > 0)) { 2684 first = addViewAbove(first, mFirstPosition); 2685 mFirstPosition--; 2686 } 2687 2688 // may have brought the very first child of the list in too far and 2689 // need to shift it back 2690 if (first.getTop() > listTop) { 2691 offsetChildrenTopAndBottom(listTop - first.getTop()); 2692 } 2693 2694 int lastIndex = getChildCount() - 1; 2695 View last = getChildAt(lastIndex); 2696 2697 // bottom view may be panned off screen 2698 while (last.getTop() > listBottom) { 2699 removeViewInLayout(last); 2700 mRecycler.addScrapView(last); 2701 last = getChildAt(--lastIndex); 2702 } 2703 } 2704 } 2705 2706 private View addViewAbove(View theView, int position) { 2707 int abovePosition = position - 1; 2708 View view = obtainView(abovePosition); 2709 int edgeOfNewChild = theView.getTop() - mDividerHeight; 2710 setupChild(view, abovePosition, edgeOfNewChild, false, mListPadding.left, false, false); 2711 return view; 2712 } 2713 2714 private View addViewBelow(View theView, int position) { 2715 int belowPosition = position + 1; 2716 View view = obtainView(belowPosition); 2717 int edgeOfNewChild = theView.getBottom() + mDividerHeight; 2718 setupChild(view, belowPosition, edgeOfNewChild, true, mListPadding.left, false, false); 2719 return view; 2720 } 2721 2722 /** 2723 * Indicates that the views created by the ListAdapter can contain focusable 2724 * items. 2725 * 2726 * @param itemsCanFocus true if items can get focus, false otherwise 2727 */ 2728 public void setItemsCanFocus(boolean itemsCanFocus) { 2729 mItemsCanFocus = itemsCanFocus; 2730 if (!itemsCanFocus) { 2731 setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS); 2732 } 2733 } 2734 2735 /** 2736 * @return Whether the views created by the ListAdapter can contain focusable 2737 * items. 2738 */ 2739 public boolean getItemsCanFocus() { 2740 return mItemsCanFocus; 2741 } 2742 2743 @Override 2744 protected void dispatchDraw(Canvas canvas) { 2745 // Draw the dividers 2746 final int dividerHeight = mDividerHeight; 2747 2748 if (dividerHeight > 0 && mDivider != null) { 2749 // Only modify the top and bottom in the loop, we set the left and right here 2750 final Rect bounds = mTempRect; 2751 bounds.left = mPaddingLeft; 2752 bounds.right = mRight - mLeft - mPaddingRight; 2753 2754 final int count = getChildCount(); 2755 final int headerCount = mHeaderViewInfos.size(); 2756 final int footerLimit = mItemCount - mFooterViewInfos.size() - 1; 2757 final boolean headerDividers = mHeaderDividersEnabled; 2758 final boolean footerDividers = mFooterDividersEnabled; 2759 final int first = mFirstPosition; 2760 2761 if (!mStackFromBottom) { 2762 int bottom; 2763 int listBottom = mBottom - mTop - mListPadding.bottom; 2764 2765 for (int i = 0; i < count; i++) { 2766 if ((headerDividers || first + i >= headerCount) && 2767 (footerDividers || first + i < footerLimit)) { 2768 View child = getChildAt(i); 2769 bottom = child.getBottom(); 2770 if (bottom < listBottom) { 2771 bounds.top = bottom; 2772 bounds.bottom = bottom + dividerHeight; 2773 drawDivider(canvas, bounds, i); 2774 } 2775 } 2776 } 2777 } else { 2778 int top; 2779 int listTop = mListPadding.top; 2780 2781 for (int i = 0; i < count; i++) { 2782 if ((headerDividers || first + i >= headerCount) && 2783 (footerDividers || first + i < footerLimit)) { 2784 View child = getChildAt(i); 2785 top = child.getTop(); 2786 if (top > listTop) { 2787 bounds.top = top - dividerHeight; 2788 bounds.bottom = top; 2789 // Give the method the child ABOVE the divider, so we 2790 // subtract one from our child 2791 // position. Give -1 when there is no child above the 2792 // divider. 2793 drawDivider(canvas, bounds, i - 1); 2794 } 2795 } 2796 } 2797 } 2798 } 2799 2800 // Draw the indicators (these should be drawn above the dividers) and children 2801 super.dispatchDraw(canvas); 2802 } 2803 2804 /** 2805 * Draws a divider for the given child in the given bounds. 2806 * 2807 * @param canvas The canvas to draw to. 2808 * @param bounds The bounds of the divider. 2809 * @param childIndex The index of child (of the View) above the divider. 2810 * This will be -1 if there is no child above the divider to be 2811 * drawn. 2812 */ 2813 void drawDivider(Canvas canvas, Rect bounds, int childIndex) { 2814 // This widget draws the same divider for all children 2815 final Drawable divider = mDivider; 2816 final boolean clipDivider = mClipDivider; 2817 2818 if (!clipDivider) { 2819 divider.setBounds(bounds); 2820 } else { 2821 canvas.save(); 2822 canvas.clipRect(bounds); 2823 } 2824 2825 divider.draw(canvas); 2826 2827 if (clipDivider) { 2828 canvas.restore(); 2829 } 2830 } 2831 2832 /** 2833 * Returns the drawable that will be drawn between each item in the list. 2834 * 2835 * @return the current drawable drawn between list elements 2836 */ 2837 public Drawable getDivider() { 2838 return mDivider; 2839 } 2840 2841 /** 2842 * Sets the drawable that will be drawn between each item in the list. If the drawable does 2843 * not have an intrinsic height, you should also call {@link #setDividerHeight(int)} 2844 * 2845 * @param divider The drawable to use. 2846 */ 2847 public void setDivider(Drawable divider) { 2848 if (divider != null) { 2849 mDividerHeight = divider.getIntrinsicHeight(); 2850 mClipDivider = divider instanceof ColorDrawable; 2851 } else { 2852 mDividerHeight = 0; 2853 mClipDivider = false; 2854 } 2855 mDivider = divider; 2856 requestLayoutIfNecessary(); 2857 } 2858 2859 /** 2860 * @return Returns the height of the divider that will be drawn between each item in the list. 2861 */ 2862 public int getDividerHeight() { 2863 return mDividerHeight; 2864 } 2865 2866 /** 2867 * Sets the height of the divider that will be drawn between each item in the list. Calling 2868 * this will override the intrinsic height as set by {@link #setDivider(Drawable)} 2869 * 2870 * @param height The new height of the divider in pixels. 2871 */ 2872 public void setDividerHeight(int height) { 2873 mDividerHeight = height; 2874 requestLayoutIfNecessary(); 2875 } 2876 2877 /** 2878 * Enables or disables the drawing of the divider for header views. 2879 * 2880 * @param headerDividersEnabled True to draw the headers, false otherwise. 2881 * 2882 * @see #setFooterDividersEnabled(boolean) 2883 * @see #addHeaderView(android.view.View) 2884 */ 2885 public void setHeaderDividersEnabled(boolean headerDividersEnabled) { 2886 mHeaderDividersEnabled = headerDividersEnabled; 2887 invalidate(); 2888 } 2889 2890 /** 2891 * Enables or disables the drawing of the divider for footer views. 2892 * 2893 * @param footerDividersEnabled True to draw the footers, false otherwise. 2894 * 2895 * @see #setHeaderDividersEnabled(boolean) 2896 * @see #addFooterView(android.view.View) 2897 */ 2898 public void setFooterDividersEnabled(boolean footerDividersEnabled) { 2899 mFooterDividersEnabled = footerDividersEnabled; 2900 invalidate(); 2901 } 2902 2903 @Override 2904 protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) { 2905 super.onFocusChanged(gainFocus, direction, previouslyFocusedRect); 2906 2907 int closetChildIndex = -1; 2908 if (gainFocus && previouslyFocusedRect != null) { 2909 previouslyFocusedRect.offset(mScrollX, mScrollY); 2910 2911 // figure out which item should be selected based on previously 2912 // focused rect 2913 Rect otherRect = mTempRect; 2914 int minDistance = Integer.MAX_VALUE; 2915 final int childCount = getChildCount(); 2916 final int firstPosition = mFirstPosition; 2917 final ListAdapter adapter = mAdapter; 2918 2919 for (int i = 0; i < childCount; i++) { 2920 // only consider selectable views 2921 if (!adapter.isEnabled(firstPosition + i)) { 2922 continue; 2923 } 2924 2925 View other = getChildAt(i); 2926 other.getDrawingRect(otherRect); 2927 offsetDescendantRectToMyCoords(other, otherRect); 2928 int distance = getDistance(previouslyFocusedRect, otherRect, direction); 2929 2930 if (distance < minDistance) { 2931 minDistance = distance; 2932 closetChildIndex = i; 2933 } 2934 } 2935 } 2936 2937 if (closetChildIndex >= 0) { 2938 setSelection(closetChildIndex + mFirstPosition); 2939 } else { 2940 requestLayout(); 2941 } 2942 } 2943 2944 2945 /* 2946 * (non-Javadoc) 2947 * 2948 * Children specified in XML are assumed to be header views. After we have 2949 * parsed them move them out of the children list and into mHeaderViews. 2950 */ 2951 @Override 2952 protected void onFinishInflate() { 2953 super.onFinishInflate(); 2954 2955 int count = getChildCount(); 2956 if (count > 0) { 2957 for (int i = 0; i < count; ++i) { 2958 addHeaderView(getChildAt(i)); 2959 } 2960 removeAllViews(); 2961 } 2962 } 2963 2964 /* (non-Javadoc) 2965 * @see android.view.View#findViewById(int) 2966 * First look in our children, then in any header and footer views that may be scrolled off. 2967 */ 2968 @Override 2969 protected View findViewTraversal(int id) { 2970 View v; 2971 v = super.findViewTraversal(id); 2972 if (v == null) { 2973 v = findViewInHeadersOrFooters(mHeaderViewInfos, id); 2974 if (v != null) { 2975 return v; 2976 } 2977 v = findViewInHeadersOrFooters(mFooterViewInfos, id); 2978 if (v != null) { 2979 return v; 2980 } 2981 } 2982 return v; 2983 } 2984 2985 /* (non-Javadoc) 2986 * 2987 * Look in the passed in list of headers or footers for the view. 2988 */ 2989 View findViewInHeadersOrFooters(ArrayList<FixedViewInfo> where, int id) { 2990 if (where != null) { 2991 int len = where.size(); 2992 View v; 2993 2994 for (int i = 0; i < len; i++) { 2995 v = where.get(i).view; 2996 2997 if (!v.isRootNamespace()) { 2998 v = v.findViewById(id); 2999 3000 if (v != null) { 3001 return v; 3002 } 3003 } 3004 } 3005 } 3006 return null; 3007 } 3008 3009 /* (non-Javadoc) 3010 * @see android.view.View#findViewWithTag(String) 3011 * First look in our children, then in any header and footer views that may be scrolled off. 3012 */ 3013 @Override 3014 protected View findViewWithTagTraversal(Object tag) { 3015 View v; 3016 v = super.findViewWithTagTraversal(tag); 3017 if (v == null) { 3018 v = findViewTagInHeadersOrFooters(mHeaderViewInfos, tag); 3019 if (v != null) { 3020 return v; 3021 } 3022 3023 v = findViewTagInHeadersOrFooters(mFooterViewInfos, tag); 3024 if (v != null) { 3025 return v; 3026 } 3027 } 3028 return v; 3029 } 3030 3031 /* (non-Javadoc) 3032 * 3033 * Look in the passed in list of headers or footers for the view with the tag. 3034 */ 3035 View findViewTagInHeadersOrFooters(ArrayList<FixedViewInfo> where, Object tag) { 3036 if (where != null) { 3037 int len = where.size(); 3038 View v; 3039 3040 for (int i = 0; i < len; i++) { 3041 v = where.get(i).view; 3042 3043 if (!v.isRootNamespace()) { 3044 v = v.findViewWithTag(tag); 3045 3046 if (v != null) { 3047 return v; 3048 } 3049 } 3050 } 3051 } 3052 return null; 3053 } 3054 3055 @Override 3056 public boolean onTouchEvent(MotionEvent ev) { 3057 if (mItemsCanFocus && ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 3058 // Don't handle edge touches immediately -- they may actually belong to one of our 3059 // descendants. 3060 return false; 3061 } 3062 return super.onTouchEvent(ev); 3063 } 3064 3065 /** 3066 * @see #setChoiceMode(int) 3067 * 3068 * @return The current choice mode 3069 */ 3070 public int getChoiceMode() { 3071 return mChoiceMode; 3072 } 3073 3074 /** 3075 * Defines the choice behavior for the List. By default, Lists do not have any choice behavior 3076 * ({@link #CHOICE_MODE_NONE}). By setting the choiceMode to {@link #CHOICE_MODE_SINGLE}, the 3077 * List allows up to one item to be in a chosen state. By setting the choiceMode to 3078 * {@link #CHOICE_MODE_MULTIPLE}, the list allows any number of items to be chosen. 3079 * 3080 * @param choiceMode One of {@link #CHOICE_MODE_NONE}, {@link #CHOICE_MODE_SINGLE}, or 3081 * {@link #CHOICE_MODE_MULTIPLE} 3082 */ 3083 public void setChoiceMode(int choiceMode) { 3084 mChoiceMode = choiceMode; 3085 if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates == null) { 3086 mCheckStates = new SparseBooleanArray(); 3087 } 3088 } 3089 3090 @Override 3091 public boolean performItemClick(View view, int position, long id) { 3092 boolean handled = false; 3093 3094 if (mChoiceMode != CHOICE_MODE_NONE) { 3095 handled = true; 3096 3097 if (mChoiceMode == CHOICE_MODE_MULTIPLE) { 3098 boolean oldValue = mCheckStates.get(position, false); 3099 mCheckStates.put(position, !oldValue); 3100 } else { 3101 boolean oldValue = mCheckStates.get(position, false); 3102 if (!oldValue) { 3103 mCheckStates.clear(); 3104 mCheckStates.put(position, true); 3105 } 3106 } 3107 3108 mDataChanged = true; 3109 rememberSyncState(); 3110 requestLayout(); 3111 } 3112 3113 handled |= super.performItemClick(view, position, id); 3114 3115 return handled; 3116 } 3117 3118 /** 3119 * Sets the checked state of the specified position. The is only valid if 3120 * the choice mode has been set to {@link #CHOICE_MODE_SINGLE} or 3121 * {@link #CHOICE_MODE_MULTIPLE}. 3122 * 3123 * @param position The item whose checked state is to be checked 3124 * @param value The new checked sate for the item 3125 */ 3126 public void setItemChecked(int position, boolean value) { 3127 if (mChoiceMode == CHOICE_MODE_NONE) { 3128 return; 3129 } 3130 3131 if (mChoiceMode == CHOICE_MODE_MULTIPLE) { 3132 mCheckStates.put(position, value); 3133 } else { 3134 boolean oldValue = mCheckStates.get(position, false); 3135 mCheckStates.clear(); 3136 if (!oldValue) { 3137 mCheckStates.put(position, true); 3138 } 3139 } 3140 3141 // Do not generate a data change while we are in the layout phase 3142 if (!mInLayout && !mBlockLayoutRequests) { 3143 mDataChanged = true; 3144 rememberSyncState(); 3145 requestLayout(); 3146 } 3147 } 3148 3149 /** 3150 * Returns the checked state of the specified position. The result is only 3151 * valid if the choice mode has not been set to {@link #CHOICE_MODE_SINGLE} 3152 * or {@link #CHOICE_MODE_MULTIPLE}. 3153 * 3154 * @param position The item whose checked state to return 3155 * @return The item's checked state 3156 * 3157 * @see #setChoiceMode(int) 3158 */ 3159 public boolean isItemChecked(int position) { 3160 if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates != null) { 3161 return mCheckStates.get(position); 3162 } 3163 3164 return false; 3165 } 3166 3167 /** 3168 * Returns the currently checked item. The result is only valid if the choice 3169 * mode has not been set to {@link #CHOICE_MODE_SINGLE}. 3170 * 3171 * @return The position of the currently checked item or 3172 * {@link #INVALID_POSITION} if nothing is selected 3173 * 3174 * @see #setChoiceMode(int) 3175 */ 3176 public int getCheckedItemPosition() { 3177 if (mChoiceMode == CHOICE_MODE_SINGLE && mCheckStates != null && mCheckStates.size() == 1) { 3178 return mCheckStates.keyAt(0); 3179 } 3180 3181 return INVALID_POSITION; 3182 } 3183 3184 /** 3185 * Returns the set of checked items in the list. The result is only valid if 3186 * the choice mode has not been set to {@link #CHOICE_MODE_SINGLE}. 3187 * 3188 * @return A SparseBooleanArray which will return true for each call to 3189 * get(int position) where position is a position in the list. 3190 */ 3191 public SparseBooleanArray getCheckedItemPositions() { 3192 if (mChoiceMode != CHOICE_MODE_NONE) { 3193 return mCheckStates; 3194 } 3195 return null; 3196 } 3197 3198 /** 3199 * Clear any choices previously set 3200 */ 3201 public void clearChoices() { 3202 if (mCheckStates != null) { 3203 mCheckStates.clear(); 3204 } 3205 } 3206 3207 static class SavedState extends BaseSavedState { 3208 SparseBooleanArray checkState; 3209 3210 /** 3211 * Constructor called from {@link ListView#onSaveInstanceState()} 3212 */ 3213 SavedState(Parcelable superState, SparseBooleanArray checkState) { 3214 super(superState); 3215 this.checkState = checkState; 3216 } 3217 3218 /** 3219 * Constructor called from {@link #CREATOR} 3220 */ 3221 private SavedState(Parcel in) { 3222 super(in); 3223 checkState = in.readSparseBooleanArray(); 3224 } 3225 3226 @Override 3227 public void writeToParcel(Parcel out, int flags) { 3228 super.writeToParcel(out, flags); 3229 out.writeSparseBooleanArray(checkState); 3230 } 3231 3232 @Override 3233 public String toString() { 3234 return "ListView.SavedState{" 3235 + Integer.toHexString(System.identityHashCode(this)) 3236 + " checkState=" + checkState + "}"; 3237 } 3238 3239 public static final Parcelable.Creator<SavedState> CREATOR 3240 = new Parcelable.Creator<SavedState>() { 3241 public SavedState createFromParcel(Parcel in) { 3242 return new SavedState(in); 3243 } 3244 3245 public SavedState[] newArray(int size) { 3246 return new SavedState[size]; 3247 } 3248 }; 3249 } 3250 3251 @Override 3252 public Parcelable onSaveInstanceState() { 3253 Parcelable superState = super.onSaveInstanceState(); 3254 return new SavedState(superState, mCheckStates); 3255 } 3256 3257 @Override 3258 public void onRestoreInstanceState(Parcelable state) { 3259 SavedState ss = (SavedState) state; 3260 3261 super.onRestoreInstanceState(ss.getSuperState()); 3262 3263 if (ss.checkState != null) { 3264 mCheckStates = ss.checkState; 3265 } 3266 3267 } 3268} 3269