ViewPager.java revision 3ce9274ccb8034c1787415c77307bbda36071bdd
1/* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.support.v4.view; 18 19import android.content.Context; 20import android.content.res.TypedArray; 21import android.database.DataSetObserver; 22import android.graphics.Canvas; 23import android.graphics.Rect; 24import android.graphics.drawable.Drawable; 25import android.os.Parcel; 26import android.os.Parcelable; 27import android.os.SystemClock; 28import android.support.v4.os.ParcelableCompat; 29import android.support.v4.os.ParcelableCompatCreatorCallbacks; 30import android.support.v4.widget.EdgeEffectCompat; 31import android.util.AttributeSet; 32import android.util.Log; 33import android.view.FocusFinder; 34import android.view.Gravity; 35import android.view.KeyEvent; 36import android.view.MotionEvent; 37import android.view.SoundEffectConstants; 38import android.view.VelocityTracker; 39import android.view.View; 40import android.view.ViewConfiguration; 41import android.view.ViewGroup; 42import android.view.ViewParent; 43import android.view.accessibility.AccessibilityEvent; 44import android.view.animation.Interpolator; 45import android.widget.Scroller; 46 47import java.util.ArrayList; 48import java.util.Collections; 49import java.util.Comparator; 50 51/** 52 * Layout manager that allows the user to flip left and right 53 * through pages of data. You supply an implementation of a 54 * {@link PagerAdapter} to generate the pages that the view shows. 55 * 56 * <p>Note this class is currently under early design and 57 * development. The API will likely change in later updates of 58 * the compatibility library, requiring changes to the source code 59 * of apps when they are compiled against the newer version.</p> 60 */ 61public class ViewPager extends ViewGroup { 62 private static final String TAG = "ViewPager"; 63 private static final boolean DEBUG = false; 64 65 private static final boolean USE_CACHE = false; 66 67 private static final int DEFAULT_OFFSCREEN_PAGES = 1; 68 private static final int MAX_SETTLE_DURATION = 600; // ms 69 70 private static final int[] LAYOUT_ATTRS = new int[] { 71 android.R.attr.layout_gravity 72 }; 73 74 static class ItemInfo { 75 Object object; 76 int position; 77 boolean scrolling; 78 } 79 80 private static final Comparator<ItemInfo> COMPARATOR = new Comparator<ItemInfo>(){ 81 @Override 82 public int compare(ItemInfo lhs, ItemInfo rhs) { 83 return lhs.position - rhs.position; 84 }}; 85 86 private static final Interpolator sInterpolator = new Interpolator() { 87 public float getInterpolation(float t) { 88 // _o(t) = t * t * ((tension + 1) * t + tension) 89 // o(t) = _o(t - 1) + 1 90 t -= 1.0f; 91 return t * t * t + 1.0f; 92 } 93 }; 94 95 private final ArrayList<ItemInfo> mItems = new ArrayList<ItemInfo>(); 96 97 private PagerAdapter mAdapter; 98 private int mCurItem; // Index of currently displayed page. 99 private int mRestoredCurItem = -1; 100 private Parcelable mRestoredAdapterState = null; 101 private ClassLoader mRestoredClassLoader = null; 102 private Scroller mScroller; 103 private PagerObserver mObserver; 104 105 private int mPageMargin; 106 private Drawable mMarginDrawable; 107 private int mTopPageBounds; 108 private int mBottomPageBounds; 109 110 private int mChildWidthMeasureSpec; 111 private int mChildHeightMeasureSpec; 112 private boolean mInLayout; 113 114 private boolean mScrollingCacheEnabled; 115 116 private boolean mPopulatePending; 117 private boolean mIsPopulating; 118 private boolean mScrolling; 119 private int mOffscreenPageLimit = DEFAULT_OFFSCREEN_PAGES; 120 121 private boolean mIsBeingDragged; 122 private boolean mIsUnableToDrag; 123 private int mTouchSlop; 124 private float mInitialMotionX; 125 /** 126 * Position of the last motion event. 127 */ 128 private float mLastMotionX; 129 private float mLastMotionY; 130 /** 131 * ID of the active pointer. This is used to retain consistency during 132 * drags/flings if multiple pointers are used. 133 */ 134 private int mActivePointerId = INVALID_POINTER; 135 /** 136 * Sentinel value for no current active pointer. 137 * Used by {@link #mActivePointerId}. 138 */ 139 private static final int INVALID_POINTER = -1; 140 141 /** 142 * Determines speed during touch scrolling 143 */ 144 private VelocityTracker mVelocityTracker; 145 private int mMinimumVelocity; 146 private int mMaximumVelocity; 147 private float mBaseLineFlingVelocity; 148 private float mFlingVelocityInfluence; 149 150 private boolean mFakeDragging; 151 private long mFakeDragBeginTime; 152 153 private EdgeEffectCompat mLeftEdge; 154 private EdgeEffectCompat mRightEdge; 155 156 private boolean mFirstLayout = true; 157 private boolean mCalledSuper; 158 private int mDecorChildCount; 159 160 private OnPageChangeListener mOnPageChangeListener; 161 private OnPageChangeListener mInternalPageChangeListener; 162 private OnAdapterChangeListener mAdapterChangeListener; 163 164 /** 165 * Indicates that the pager is in an idle, settled state. The current page 166 * is fully in view and no animation is in progress. 167 */ 168 public static final int SCROLL_STATE_IDLE = 0; 169 170 /** 171 * Indicates that the pager is currently being dragged by the user. 172 */ 173 public static final int SCROLL_STATE_DRAGGING = 1; 174 175 /** 176 * Indicates that the pager is in the process of settling to a final position. 177 */ 178 public static final int SCROLL_STATE_SETTLING = 2; 179 180 private int mScrollState = SCROLL_STATE_IDLE; 181 182 /** 183 * Callback interface for responding to changing state of the selected page. 184 */ 185 public interface OnPageChangeListener { 186 187 /** 188 * This method will be invoked when the current page is scrolled, either as part 189 * of a programmatically initiated smooth scroll or a user initiated touch scroll. 190 * 191 * @param position Position index of the first page currently being displayed. 192 * Page position+1 will be visible if positionOffset is nonzero. 193 * @param positionOffset Value from [0, 1) indicating the offset from the page at position. 194 * @param positionOffsetPixels Value in pixels indicating the offset from position. 195 */ 196 public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels); 197 198 /** 199 * This method will be invoked when a new page becomes selected. Animation is not 200 * necessarily complete. 201 * 202 * @param position Position index of the new selected page. 203 */ 204 public void onPageSelected(int position); 205 206 /** 207 * Called when the scroll state changes. Useful for discovering when the user 208 * begins dragging, when the pager is automatically settling to the current page, 209 * or when it is fully stopped/idle. 210 * 211 * @param state The new scroll state. 212 * @see ViewPager#SCROLL_STATE_IDLE 213 * @see ViewPager#SCROLL_STATE_DRAGGING 214 * @see ViewPager#SCROLL_STATE_SETTLING 215 */ 216 public void onPageScrollStateChanged(int state); 217 } 218 219 /** 220 * Simple implementation of the {@link OnPageChangeListener} interface with stub 221 * implementations of each method. Extend this if you do not intend to override 222 * every method of {@link OnPageChangeListener}. 223 */ 224 public static class SimpleOnPageChangeListener implements OnPageChangeListener { 225 @Override 226 public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { 227 // This space for rent 228 } 229 230 @Override 231 public void onPageSelected(int position) { 232 // This space for rent 233 } 234 235 @Override 236 public void onPageScrollStateChanged(int state) { 237 // This space for rent 238 } 239 } 240 241 /** 242 * Used internally to monitor when adapters are switched. 243 */ 244 interface OnAdapterChangeListener { 245 public void onAdapterChanged(PagerAdapter oldAdapter, PagerAdapter newAdapter); 246 } 247 248 /** 249 * Used internally to tag special types of child views that should be added as 250 * pager decorations by default. 251 */ 252 interface Decor {} 253 254 public ViewPager(Context context) { 255 super(context); 256 initViewPager(); 257 } 258 259 public ViewPager(Context context, AttributeSet attrs) { 260 super(context, attrs); 261 initViewPager(); 262 } 263 264 void initViewPager() { 265 setWillNotDraw(false); 266 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 267 setFocusable(true); 268 final Context context = getContext(); 269 mScroller = new Scroller(context, sInterpolator); 270 final ViewConfiguration configuration = ViewConfiguration.get(context); 271 mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration); 272 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 273 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 274 mLeftEdge = new EdgeEffectCompat(context); 275 mRightEdge = new EdgeEffectCompat(context); 276 277 float density = context.getResources().getDisplayMetrics().density; 278 mBaseLineFlingVelocity = 2500.0f * density; 279 mFlingVelocityInfluence = 0.4f; 280 } 281 282 private void setScrollState(int newState) { 283 if (mScrollState == newState) { 284 return; 285 } 286 287 mScrollState = newState; 288 if (mOnPageChangeListener != null) { 289 mOnPageChangeListener.onPageScrollStateChanged(newState); 290 } 291 } 292 293 /** 294 * Set a PagerAdapter that will supply views for this pager as needed. 295 * 296 * @param adapter Adapter to use 297 */ 298 public void setAdapter(PagerAdapter adapter) { 299 if (mAdapter != null) { 300 mAdapter.unregisterDataSetObserver(mObserver); 301 mAdapter.startUpdate(this); 302 for (int i = 0; i < mItems.size(); i++) { 303 final ItemInfo ii = mItems.get(i); 304 mAdapter.destroyItem(this, ii.position, ii.object); 305 } 306 mAdapter.finishUpdate(this); 307 mItems.clear(); 308 removeAllViews(); 309 mCurItem = 0; 310 scrollTo(0, 0); 311 } 312 313 final PagerAdapter oldAdapter = mAdapter; 314 mAdapter = adapter; 315 316 if (mAdapter != null) { 317 if (mObserver == null) { 318 mObserver = new PagerObserver(); 319 } 320 mAdapter.registerDataSetObserver(mObserver); 321 mPopulatePending = false; 322 if (mRestoredCurItem >= 0) { 323 mAdapter.restoreState(mRestoredAdapterState, mRestoredClassLoader); 324 setCurrentItemInternal(mRestoredCurItem, false, true); 325 mRestoredCurItem = -1; 326 mRestoredAdapterState = null; 327 mRestoredClassLoader = null; 328 } else { 329 populate(); 330 } 331 } 332 333 if (mAdapterChangeListener != null && oldAdapter != adapter) { 334 mAdapterChangeListener.onAdapterChanged(oldAdapter, adapter); 335 } 336 } 337 338 /** 339 * Retrieve the current adapter supplying pages. 340 * 341 * @return The currently registered PagerAdapter 342 */ 343 public PagerAdapter getAdapter() { 344 return mAdapter; 345 } 346 347 void setOnAdapterChangeListener(OnAdapterChangeListener listener) { 348 mAdapterChangeListener = listener; 349 } 350 351 /** 352 * Set the currently selected page. If the ViewPager has already been through its first 353 * layout there will be a smooth animated transition between the current item and the 354 * specified item. 355 * 356 * @param item Item index to select 357 */ 358 public void setCurrentItem(int item) { 359 mPopulatePending = false; 360 setCurrentItemInternal(item, !mFirstLayout, false); 361 } 362 363 /** 364 * Set the currently selected page. 365 * 366 * @param item Item index to select 367 * @param smoothScroll True to smoothly scroll to the new item, false to transition immediately 368 */ 369 public void setCurrentItem(int item, boolean smoothScroll) { 370 mPopulatePending = false; 371 setCurrentItemInternal(item, smoothScroll, false); 372 } 373 374 public int getCurrentItem() { 375 return mCurItem; 376 } 377 378 void setCurrentItemInternal(int item, boolean smoothScroll, boolean always) { 379 setCurrentItemInternal(item, smoothScroll, always, 0); 380 } 381 382 void setCurrentItemInternal(int item, boolean smoothScroll, boolean always, int velocity) { 383 if (mAdapter == null || mAdapter.getCount() <= 0) { 384 setScrollingCacheEnabled(false); 385 return; 386 } 387 if (!always && mCurItem == item && mItems.size() != 0) { 388 setScrollingCacheEnabled(false); 389 return; 390 } 391 if (item < 0) { 392 item = 0; 393 } else if (item >= mAdapter.getCount()) { 394 item = mAdapter.getCount() - 1; 395 } 396 final int pageLimit = mOffscreenPageLimit; 397 if (item > (mCurItem + pageLimit) || item < (mCurItem - pageLimit)) { 398 // We are doing a jump by more than one page. To avoid 399 // glitches, we want to keep all current pages in the view 400 // until the scroll ends. 401 for (int i=0; i<mItems.size(); i++) { 402 mItems.get(i).scrolling = true; 403 } 404 } 405 final boolean dispatchSelected = mCurItem != item; 406 mCurItem = item; 407 populate(); 408 final int destX = (getWidth() + mPageMargin) * item; 409 if (smoothScroll) { 410 smoothScrollTo(destX, 0, velocity); 411 if (dispatchSelected && mOnPageChangeListener != null) { 412 mOnPageChangeListener.onPageSelected(item); 413 } 414 if (dispatchSelected && mInternalPageChangeListener != null) { 415 mInternalPageChangeListener.onPageSelected(item); 416 } 417 } else { 418 if (dispatchSelected && mOnPageChangeListener != null) { 419 mOnPageChangeListener.onPageSelected(item); 420 } 421 if (dispatchSelected && mInternalPageChangeListener != null) { 422 mInternalPageChangeListener.onPageSelected(item); 423 } 424 completeScroll(); 425 scrollTo(destX, 0); 426 } 427 } 428 429 /** 430 * Set a listener that will be invoked whenever the page changes or is incrementally 431 * scrolled. See {@link OnPageChangeListener}. 432 * 433 * @param listener Listener to set 434 */ 435 public void setOnPageChangeListener(OnPageChangeListener listener) { 436 mOnPageChangeListener = listener; 437 } 438 439 /** 440 * Set a separate OnPageChangeListener for internal use by the support library. 441 * 442 * @param listener Listener to set 443 * @return The old listener that was set, if any. 444 */ 445 OnPageChangeListener setInternalPageChangeListener(OnPageChangeListener listener) { 446 OnPageChangeListener oldListener = mInternalPageChangeListener; 447 mInternalPageChangeListener = listener; 448 return oldListener; 449 } 450 451 /** 452 * Returns the number of pages that will be retained to either side of the 453 * current page in the view hierarchy in an idle state. Defaults to 1. 454 * 455 * @return How many pages will be kept offscreen on either side 456 * @see #setOffscreenPageLimit(int) 457 */ 458 public int getOffscreenPageLimit() { 459 return mOffscreenPageLimit; 460 } 461 462 /** 463 * Set the number of pages that should be retained to either side of the 464 * current page in the view hierarchy in an idle state. Pages beyond this 465 * limit will be recreated from the adapter when needed. 466 * 467 * <p>This is offered as an optimization. If you know in advance the number 468 * of pages you will need to support or have lazy-loading mechanisms in place 469 * on your pages, tweaking this setting can have benefits in perceived smoothness 470 * of paging animations and interaction. If you have a small number of pages (3-4) 471 * that you can keep active all at once, less time will be spent in layout for 472 * newly created view subtrees as the user pages back and forth.</p> 473 * 474 * <p>You should keep this limit low, especially if your pages have complex layouts. 475 * This setting defaults to 1.</p> 476 * 477 * @param limit How many pages will be kept offscreen in an idle state. 478 */ 479 public void setOffscreenPageLimit(int limit) { 480 if (limit < DEFAULT_OFFSCREEN_PAGES) { 481 Log.w(TAG, "Requested offscreen page limit " + limit + " too small; defaulting to " + 482 DEFAULT_OFFSCREEN_PAGES); 483 limit = DEFAULT_OFFSCREEN_PAGES; 484 } 485 if (limit != mOffscreenPageLimit) { 486 mOffscreenPageLimit = limit; 487 populate(); 488 } 489 } 490 491 /** 492 * Set the margin between pages. 493 * 494 * @param marginPixels Distance between adjacent pages in pixels 495 * @see #getPageMargin() 496 * @see #setPageMarginDrawable(Drawable) 497 * @see #setPageMarginDrawable(int) 498 */ 499 public void setPageMargin(int marginPixels) { 500 final int oldMargin = mPageMargin; 501 mPageMargin = marginPixels; 502 503 final int width = getWidth(); 504 recomputeScrollPosition(width, width, marginPixels, oldMargin); 505 506 requestLayout(); 507 } 508 509 /** 510 * Return the margin between pages. 511 * 512 * @return The size of the margin in pixels 513 */ 514 public int getPageMargin() { 515 return mPageMargin; 516 } 517 518 /** 519 * Set a drawable that will be used to fill the margin between pages. 520 * 521 * @param d Drawable to display between pages 522 */ 523 public void setPageMarginDrawable(Drawable d) { 524 mMarginDrawable = d; 525 if (d != null) refreshDrawableState(); 526 setWillNotDraw(d == null); 527 invalidate(); 528 } 529 530 /** 531 * Set a drawable that will be used to fill the margin between pages. 532 * 533 * @param resId Resource ID of a drawable to display between pages 534 */ 535 public void setPageMarginDrawable(int resId) { 536 setPageMarginDrawable(getContext().getResources().getDrawable(resId)); 537 } 538 539 @Override 540 protected boolean verifyDrawable(Drawable who) { 541 return super.verifyDrawable(who) || who == mMarginDrawable; 542 } 543 544 @Override 545 protected void drawableStateChanged() { 546 super.drawableStateChanged(); 547 final Drawable d = mMarginDrawable; 548 if (d != null && d.isStateful()) { 549 d.setState(getDrawableState()); 550 } 551 } 552 553 // We want the duration of the page snap animation to be influenced by the distance that 554 // the screen has to travel, however, we don't want this duration to be effected in a 555 // purely linear fashion. Instead, we use this method to moderate the effect that the distance 556 // of travel has on the overall snap duration. 557 float distanceInfluenceForSnapDuration(float f) { 558 f -= 0.5f; // center the values about 0. 559 f *= 0.3f * Math.PI / 2.0f; 560 return (float) Math.sin(f); 561 } 562 563 /** 564 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 565 * 566 * @param x the number of pixels to scroll by on the X axis 567 * @param y the number of pixels to scroll by on the Y axis 568 */ 569 void smoothScrollTo(int x, int y) { 570 smoothScrollTo(x, y, 0); 571 } 572 573 /** 574 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 575 * 576 * @param x the number of pixels to scroll by on the X axis 577 * @param y the number of pixels to scroll by on the Y axis 578 * @param velocity the velocity associated with a fling, if applicable. (0 otherwise) 579 */ 580 void smoothScrollTo(int x, int y, int velocity) { 581 if (getChildCount() == 0) { 582 // Nothing to do. 583 setScrollingCacheEnabled(false); 584 return; 585 } 586 int sx = getScrollX(); 587 int sy = getScrollY(); 588 int dx = x - sx; 589 int dy = y - sy; 590 if (dx == 0 && dy == 0) { 591 completeScroll(); 592 setScrollState(SCROLL_STATE_IDLE); 593 return; 594 } 595 596 setScrollingCacheEnabled(true); 597 mScrolling = true; 598 setScrollState(SCROLL_STATE_SETTLING); 599 600 final float pageDelta = (float) Math.abs(dx) / (getWidth() + mPageMargin); 601 int duration = (int) (pageDelta * 100); 602 603 velocity = Math.abs(velocity); 604 if (velocity > 0) { 605 duration += (duration / (velocity / mBaseLineFlingVelocity)) * mFlingVelocityInfluence; 606 } else { 607 duration += 100; 608 } 609 duration = Math.min(duration, MAX_SETTLE_DURATION); 610 611 mScroller.startScroll(sx, sy, dx, dy, duration); 612 invalidate(); 613 } 614 615 void addNewItem(int position, int index) { 616 ItemInfo ii = new ItemInfo(); 617 ii.position = position; 618 ii.object = mAdapter.instantiateItem(this, position); 619 if (index < 0) { 620 mItems.add(ii); 621 } else { 622 mItems.add(index, ii); 623 } 624 } 625 626 void dataSetChanged() { 627 // This method only gets called if our observer is attached, so mAdapter is non-null. 628 629 boolean needPopulate = mItems.size() < 3 && mItems.size() < mAdapter.getCount(); 630 int newCurrItem = -1; 631 632 boolean isUpdating = false; 633 for (int i = 0; i < mItems.size(); i++) { 634 final ItemInfo ii = mItems.get(i); 635 final int newPos = mAdapter.getItemPosition(ii.object); 636 637 if (newPos == PagerAdapter.POSITION_UNCHANGED) { 638 continue; 639 } 640 641 if (newPos == PagerAdapter.POSITION_NONE) { 642 mItems.remove(i); 643 i--; 644 645 if (!isUpdating) { 646 mAdapter.startUpdate(this); 647 isUpdating = true; 648 } 649 650 mAdapter.destroyItem(this, ii.position, ii.object); 651 needPopulate = true; 652 653 if (mCurItem == ii.position) { 654 // Keep the current item in the valid range 655 newCurrItem = Math.max(0, Math.min(mCurItem, mAdapter.getCount() - 1)); 656 } 657 continue; 658 } 659 660 if (ii.position != newPos) { 661 if (ii.position == mCurItem) { 662 // Our current item changed position. Follow it. 663 newCurrItem = newPos; 664 } 665 666 ii.position = newPos; 667 needPopulate = true; 668 } 669 } 670 671 if (isUpdating) { 672 mAdapter.finishUpdate(this); 673 } 674 675 Collections.sort(mItems, COMPARATOR); 676 677 if (newCurrItem >= 0) { 678 // TODO This currently causes a jump. 679 setCurrentItemInternal(newCurrItem, false, true); 680 needPopulate = true; 681 } 682 if (needPopulate) { 683 populate(); 684 requestLayout(); 685 } 686 } 687 688 void populate() { 689 if (mAdapter == null) { 690 return; 691 } 692 693 // Bail now if we are waiting to populate. This is to hold off 694 // on creating views from the time the user releases their finger to 695 // fling to a new position until we have finished the scroll to 696 // that position, avoiding glitches from happening at that point. 697 if (mPopulatePending) { 698 if (DEBUG) Log.i(TAG, "populate is pending, skipping for now..."); 699 return; 700 } 701 702 // Also, don't populate until we are attached to a window. This is to 703 // avoid trying to populate before we have restored our view hierarchy 704 // state and conflicting with what is restored. 705 if (getWindowToken() == null) { 706 return; 707 } 708 709 mIsPopulating = true; 710 mAdapter.startUpdate(this); 711 712 final int pageLimit = mOffscreenPageLimit; 713 final int startPos = Math.max(0, mCurItem - pageLimit); 714 final int N = mAdapter.getCount(); 715 final int endPos = Math.min(N-1, mCurItem + pageLimit); 716 717 if (DEBUG) Log.v(TAG, "populating: startPos=" + startPos + " endPos=" + endPos); 718 719 // Add and remove pages in the existing list. 720 int lastPos = -1; 721 for (int i=0; i<mItems.size(); i++) { 722 ItemInfo ii = mItems.get(i); 723 if ((ii.position < startPos || ii.position > endPos) && !ii.scrolling) { 724 if (DEBUG) Log.i(TAG, "removing: " + ii.position + " @ " + i); 725 mItems.remove(i); 726 i--; 727 mAdapter.destroyItem(this, ii.position, ii.object); 728 } else if (lastPos < endPos && ii.position > startPos) { 729 // The next item is outside of our range, but we have a gap 730 // between it and the last item where we want to have a page 731 // shown. Fill in the gap. 732 lastPos++; 733 if (lastPos < startPos) { 734 lastPos = startPos; 735 } 736 while (lastPos <= endPos && lastPos < ii.position) { 737 if (DEBUG) Log.i(TAG, "inserting: " + lastPos + " @ " + i); 738 addNewItem(lastPos, i); 739 lastPos++; 740 i++; 741 } 742 } 743 lastPos = ii.position; 744 } 745 746 // Add any new pages we need at the end. 747 lastPos = mItems.size() > 0 ? mItems.get(mItems.size()-1).position : -1; 748 if (lastPos < endPos) { 749 lastPos++; 750 lastPos = lastPos > startPos ? lastPos : startPos; 751 while (lastPos <= endPos) { 752 if (DEBUG) Log.i(TAG, "appending: " + lastPos); 753 addNewItem(lastPos, -1); 754 lastPos++; 755 } 756 } 757 758 if (DEBUG) { 759 Log.i(TAG, "Current page list:"); 760 for (int i=0; i<mItems.size(); i++) { 761 Log.i(TAG, "#" + i + ": page " + mItems.get(i).position); 762 } 763 } 764 765 ItemInfo curItem = null; 766 for (int i=0; i<mItems.size(); i++) { 767 if (mItems.get(i).position == mCurItem) { 768 curItem = mItems.get(i); 769 break; 770 } 771 } 772 mAdapter.setPrimaryItem(this, mCurItem, curItem != null ? curItem.object : null); 773 774 mAdapter.finishUpdate(this); 775 mIsPopulating = false; 776 777 if (hasFocus()) { 778 View currentFocused = findFocus(); 779 ItemInfo ii = currentFocused != null ? infoForAnyChild(currentFocused) : null; 780 if (ii == null || ii.position != mCurItem) { 781 for (int i=0; i<getChildCount(); i++) { 782 View child = getChildAt(i); 783 ii = infoForChild(child); 784 if (ii != null && ii.position == mCurItem) { 785 if (child.requestFocus(FOCUS_FORWARD)) { 786 break; 787 } 788 } 789 } 790 } 791 } 792 } 793 794 public static class SavedState extends BaseSavedState { 795 int position; 796 Parcelable adapterState; 797 ClassLoader loader; 798 799 public SavedState(Parcelable superState) { 800 super(superState); 801 } 802 803 @Override 804 public void writeToParcel(Parcel out, int flags) { 805 super.writeToParcel(out, flags); 806 out.writeInt(position); 807 out.writeParcelable(adapterState, flags); 808 } 809 810 @Override 811 public String toString() { 812 return "FragmentPager.SavedState{" 813 + Integer.toHexString(System.identityHashCode(this)) 814 + " position=" + position + "}"; 815 } 816 817 public static final Parcelable.Creator<SavedState> CREATOR 818 = ParcelableCompat.newCreator(new ParcelableCompatCreatorCallbacks<SavedState>() { 819 @Override 820 public SavedState createFromParcel(Parcel in, ClassLoader loader) { 821 return new SavedState(in, loader); 822 } 823 @Override 824 public SavedState[] newArray(int size) { 825 return new SavedState[size]; 826 } 827 }); 828 829 SavedState(Parcel in, ClassLoader loader) { 830 super(in); 831 if (loader == null) { 832 loader = getClass().getClassLoader(); 833 } 834 position = in.readInt(); 835 adapterState = in.readParcelable(loader); 836 this.loader = loader; 837 } 838 } 839 840 @Override 841 public Parcelable onSaveInstanceState() { 842 Parcelable superState = super.onSaveInstanceState(); 843 SavedState ss = new SavedState(superState); 844 ss.position = mCurItem; 845 if (mAdapter != null) { 846 ss.adapterState = mAdapter.saveState(); 847 } 848 return ss; 849 } 850 851 @Override 852 public void onRestoreInstanceState(Parcelable state) { 853 if (!(state instanceof SavedState)) { 854 super.onRestoreInstanceState(state); 855 return; 856 } 857 858 SavedState ss = (SavedState)state; 859 super.onRestoreInstanceState(ss.getSuperState()); 860 861 if (mAdapter != null) { 862 mAdapter.restoreState(ss.adapterState, ss.loader); 863 setCurrentItemInternal(ss.position, false, true); 864 } else { 865 mRestoredCurItem = ss.position; 866 mRestoredAdapterState = ss.adapterState; 867 mRestoredClassLoader = ss.loader; 868 } 869 } 870 871 @Override 872 public void addView(View child, int index, ViewGroup.LayoutParams params) { 873 if (!checkLayoutParams(params)) { 874 params = generateLayoutParams(params); 875 } 876 final LayoutParams lp = (LayoutParams) params; 877 lp.isDecor |= child instanceof Decor; 878 if (mInLayout) { 879 if (lp != null && lp.isDecor) { 880 throw new IllegalStateException("Cannot add pager decor view during layout"); 881 } 882 addViewInLayout(child, index, params); 883 child.measure(mChildWidthMeasureSpec, mChildHeightMeasureSpec); 884 } else { 885 super.addView(child, index, params); 886 } 887 888 if (USE_CACHE) { 889 if (child.getVisibility() != GONE) { 890 child.setDrawingCacheEnabled(mScrollingCacheEnabled); 891 } else { 892 child.setDrawingCacheEnabled(false); 893 } 894 } 895 } 896 897 ItemInfo infoForChild(View child) { 898 for (int i=0; i<mItems.size(); i++) { 899 ItemInfo ii = mItems.get(i); 900 if (mAdapter.isViewFromObject(child, ii.object)) { 901 return ii; 902 } 903 } 904 return null; 905 } 906 907 ItemInfo infoForAnyChild(View child) { 908 ViewParent parent; 909 while ((parent=child.getParent()) != this) { 910 if (parent == null || !(parent instanceof View)) { 911 return null; 912 } 913 child = (View)parent; 914 } 915 return infoForChild(child); 916 } 917 918 @Override 919 protected void onAttachedToWindow() { 920 super.onAttachedToWindow(); 921 mFirstLayout = true; 922 } 923 924 @Override 925 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 926 // For simple implementation, or internal size is always 0. 927 // We depend on the container to specify the layout size of 928 // our view. We can't really know what it is since we will be 929 // adding and removing different arbitrary views and do not 930 // want the layout to change as this happens. 931 setMeasuredDimension(getDefaultSize(0, widthMeasureSpec), 932 getDefaultSize(0, heightMeasureSpec)); 933 934 // Children are just made to fill our space. 935 int childWidthSize = getMeasuredWidth() - getPaddingLeft() - getPaddingRight(); 936 int childHeightSize = getMeasuredHeight() - getPaddingTop() - getPaddingBottom(); 937 938 /* 939 * Make sure all children have been properly measured. Decor views first. 940 * Right now we cheat and make this less complicated by assuming decor 941 * views won't intersect. We will pin to edges based on gravity. 942 */ 943 final int size = getChildCount(); 944 for (int i = 0; i < size; ++i) { 945 final View child = getChildAt(i); 946 if (child.getVisibility() != GONE) { 947 final LayoutParams lp = (LayoutParams) child.getLayoutParams(); 948 if (lp != null && lp.isDecor) { 949 final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; 950 final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK; 951 Log.d(TAG, "gravity: " + lp.gravity + " hgrav: " + hgrav + " vgrav: " + vgrav); 952 int widthMode = MeasureSpec.AT_MOST; 953 int heightMode = MeasureSpec.AT_MOST; 954 boolean consumeVertical = vgrav == Gravity.TOP || vgrav == Gravity.BOTTOM; 955 boolean consumeHorizontal = hgrav == Gravity.LEFT || hgrav == Gravity.RIGHT; 956 957 if (consumeVertical) { 958 widthMode = MeasureSpec.EXACTLY; 959 } else if (consumeHorizontal) { 960 heightMode = MeasureSpec.EXACTLY; 961 } 962 963 final int widthSpec = MeasureSpec.makeMeasureSpec(childWidthSize, widthMode); 964 final int heightSpec = MeasureSpec.makeMeasureSpec(childHeightSize, heightMode); 965 child.measure(widthSpec, heightSpec); 966 967 if (consumeVertical) { 968 childHeightSize -= child.getMeasuredHeight(); 969 } else if (consumeHorizontal) { 970 childWidthSize -= child.getMeasuredWidth(); 971 } 972 } 973 } 974 } 975 976 mChildWidthMeasureSpec = MeasureSpec.makeMeasureSpec(childWidthSize, MeasureSpec.EXACTLY); 977 mChildHeightMeasureSpec = MeasureSpec.makeMeasureSpec(childHeightSize, MeasureSpec.EXACTLY); 978 979 // Make sure we have created all fragments that we need to have shown. 980 mInLayout = true; 981 populate(); 982 mInLayout = false; 983 984 // Page views next. 985 for (int i = 0; i < size; ++i) { 986 final View child = getChildAt(i); 987 if (child.getVisibility() != GONE) { 988 if (DEBUG) Log.v(TAG, "Measuring #" + i + " " + child 989 + ": " + mChildWidthMeasureSpec); 990 991 final LayoutParams lp = (LayoutParams) child.getLayoutParams(); 992 if (lp == null || !lp.isDecor) { 993 child.measure(mChildWidthMeasureSpec, mChildHeightMeasureSpec); 994 } 995 } 996 } 997 } 998 999 @Override 1000 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1001 super.onSizeChanged(w, h, oldw, oldh); 1002 1003 // Make sure scroll position is set correctly. 1004 if (w != oldw) { 1005 recomputeScrollPosition(w, oldw, mPageMargin, mPageMargin); 1006 } 1007 } 1008 1009 private void recomputeScrollPosition(int width, int oldWidth, int margin, int oldMargin) { 1010 final int widthWithMargin = width + margin; 1011 if (oldWidth > 0) { 1012 final int oldScrollPos = getScrollX(); 1013 final int oldwwm = oldWidth + oldMargin; 1014 final int oldScrollItem = oldScrollPos / oldwwm; 1015 final float scrollOffset = (float) (oldScrollPos % oldwwm) / oldwwm; 1016 final int scrollPos = (int) ((oldScrollItem + scrollOffset) * widthWithMargin); 1017 scrollTo(scrollPos, getScrollY()); 1018 if (!mScroller.isFinished()) { 1019 // We now return to your regularly scheduled scroll, already in progress. 1020 final int newDuration = mScroller.getDuration() - mScroller.timePassed(); 1021 mScroller.startScroll(scrollPos, 0, mCurItem * widthWithMargin, 0, newDuration); 1022 } 1023 } else { 1024 int scrollPos = mCurItem * widthWithMargin; 1025 if (scrollPos != getScrollX()) { 1026 completeScroll(); 1027 scrollTo(scrollPos, getScrollY()); 1028 } 1029 } 1030 } 1031 1032 @Override 1033 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1034 mInLayout = true; 1035 populate(); 1036 mInLayout = false; 1037 1038 final int count = getChildCount(); 1039 int width = r - l; 1040 int height = b - t; 1041 int paddingLeft = getPaddingLeft(); 1042 int paddingTop = getPaddingTop(); 1043 int paddingRight = getPaddingRight(); 1044 int paddingBottom = getPaddingBottom(); 1045 final int scrollX = getScrollX(); 1046 1047 int decorCount = 0; 1048 1049 for (int i = 0; i < count; i++) { 1050 final View child = getChildAt(i); 1051 if (child.getVisibility() != GONE) { 1052 final LayoutParams lp = (LayoutParams) child.getLayoutParams(); 1053 ItemInfo ii; 1054 int childLeft = 0; 1055 int childTop = 0; 1056 if (lp.isDecor) { 1057 final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; 1058 final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK; 1059 switch (hgrav) { 1060 default: 1061 childLeft = paddingLeft; 1062 break; 1063 case Gravity.LEFT: 1064 childLeft = paddingLeft; 1065 paddingLeft += child.getMeasuredWidth(); 1066 break; 1067 case Gravity.CENTER_HORIZONTAL: 1068 childLeft = Math.max((width - child.getMeasuredWidth()) / 2, 1069 paddingLeft); 1070 break; 1071 case Gravity.RIGHT: 1072 childLeft = width - paddingRight - child.getMeasuredWidth(); 1073 paddingRight += child.getMeasuredWidth(); 1074 break; 1075 } 1076 switch (vgrav) { 1077 default: 1078 childTop = paddingTop; 1079 break; 1080 case Gravity.TOP: 1081 childTop = paddingTop; 1082 paddingTop += child.getMeasuredHeight(); 1083 break; 1084 case Gravity.CENTER_VERTICAL: 1085 childTop = Math.max((height - child.getMeasuredHeight()) / 2, 1086 paddingTop); 1087 break; 1088 case Gravity.BOTTOM: 1089 childTop = height - paddingBottom - child.getMeasuredHeight(); 1090 paddingBottom += child.getMeasuredHeight(); 1091 break; 1092 } 1093 childLeft += scrollX; 1094 decorCount++; 1095 } else if ((ii = infoForChild(child)) != null) { 1096 int loff = (width + mPageMargin) * ii.position; 1097 childLeft = paddingLeft + loff; 1098 childTop = paddingTop; 1099 if (DEBUG) Log.v(TAG, "Positioning #" + i + " " + child + " f=" + ii.object 1100 + ":" + childLeft + "," + childTop + " " + child.getMeasuredWidth() 1101 + "x" + child.getMeasuredHeight()); 1102 } 1103 child.layout(childLeft, childTop, 1104 childLeft + child.getMeasuredWidth(), 1105 childTop + child.getMeasuredHeight()); 1106 } 1107 } 1108 mTopPageBounds = paddingTop; 1109 mBottomPageBounds = height - paddingBottom; 1110 mDecorChildCount = decorCount; 1111 mFirstLayout = false; 1112 } 1113 1114 @Override 1115 public void computeScroll() { 1116 if (DEBUG) Log.i(TAG, "computeScroll: finished=" + mScroller.isFinished()); 1117 if (!mScroller.isFinished()) { 1118 if (mScroller.computeScrollOffset()) { 1119 if (DEBUG) Log.i(TAG, "computeScroll: still scrolling"); 1120 int oldX = getScrollX(); 1121 int oldY = getScrollY(); 1122 int x = mScroller.getCurrX(); 1123 int y = mScroller.getCurrY(); 1124 1125 if (oldX != x || oldY != y) { 1126 scrollTo(x, y); 1127 pageScrolled(x); 1128 } 1129 1130 // Keep on drawing until the animation has finished. 1131 invalidate(); 1132 return; 1133 } 1134 } 1135 1136 // Done with scroll, clean up state. 1137 completeScroll(); 1138 } 1139 1140 private void pageScrolled(int xpos) { 1141 final int widthWithMargin = getWidth() + mPageMargin; 1142 final int position = xpos / widthWithMargin; 1143 final int offsetPixels = xpos % widthWithMargin; 1144 final float offset = (float) offsetPixels / widthWithMargin; 1145 1146 mCalledSuper = false; 1147 onPageScrolled(position, offset, offsetPixels); 1148 if (!mCalledSuper) { 1149 throw new IllegalStateException( 1150 "onPageScrolled did not call superclass implementation"); 1151 } 1152 } 1153 1154 /** 1155 * This method will be invoked when the current page is scrolled, either as part 1156 * of a programmatically initiated smooth scroll or a user initiated touch scroll. 1157 * If you override this method you must call through to the superclass implementation 1158 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled 1159 * returns. 1160 * 1161 * @param position Position index of the first page currently being displayed. 1162 * Page position+1 will be visible if positionOffset is nonzero. 1163 * @param offset Value from [0, 1) indicating the offset from the page at position. 1164 * @param offsetPixels Value in pixels indicating the offset from position. 1165 */ 1166 protected void onPageScrolled(int position, float offset, int offsetPixels) { 1167 // Offset any decor views if needed - keep them on-screen at all times. 1168 if (mDecorChildCount > 0) { 1169 final int scrollX = getScrollX(); 1170 int paddingLeft = getPaddingLeft(); 1171 int paddingRight = getPaddingRight(); 1172 final int width = getWidth(); 1173 final int childCount = getChildCount(); 1174 for (int i = 0; i < childCount; i++) { 1175 final View child = getChildAt(i); 1176 final LayoutParams lp = (LayoutParams) child.getLayoutParams(); 1177 if (!lp.isDecor) continue; 1178 1179 final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; 1180 int childLeft = 0; 1181 switch (hgrav) { 1182 default: 1183 childLeft = paddingLeft; 1184 break; 1185 case Gravity.LEFT: 1186 childLeft = paddingLeft; 1187 paddingLeft += child.getWidth(); 1188 break; 1189 case Gravity.CENTER_HORIZONTAL: 1190 childLeft = Math.max((width - child.getMeasuredWidth()) / 2, 1191 paddingLeft); 1192 break; 1193 case Gravity.RIGHT: 1194 childLeft = width - paddingRight - child.getMeasuredWidth(); 1195 paddingRight += child.getMeasuredWidth(); 1196 break; 1197 } 1198 childLeft += scrollX; 1199 1200 final int childOffset = childLeft - child.getLeft(); 1201 if (childOffset != 0) { 1202 child.offsetLeftAndRight(childOffset); 1203 } 1204 } 1205 } 1206 1207 if (mOnPageChangeListener != null) { 1208 mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels); 1209 } 1210 if (mInternalPageChangeListener != null) { 1211 mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels); 1212 } 1213 mCalledSuper = true; 1214 } 1215 1216 private void completeScroll() { 1217 boolean needPopulate = mScrolling; 1218 if (needPopulate) { 1219 // Done with scroll, no longer want to cache view drawing. 1220 setScrollingCacheEnabled(false); 1221 mScroller.abortAnimation(); 1222 int oldX = getScrollX(); 1223 int oldY = getScrollY(); 1224 int x = mScroller.getCurrX(); 1225 int y = mScroller.getCurrY(); 1226 if (oldX != x || oldY != y) { 1227 scrollTo(x, y); 1228 } 1229 setScrollState(SCROLL_STATE_IDLE); 1230 } 1231 mPopulatePending = false; 1232 mScrolling = false; 1233 for (int i=0; i<mItems.size(); i++) { 1234 ItemInfo ii = mItems.get(i); 1235 if (ii.scrolling) { 1236 needPopulate = true; 1237 ii.scrolling = false; 1238 } 1239 } 1240 if (needPopulate) { 1241 populate(); 1242 } 1243 } 1244 1245 @Override 1246 public boolean onInterceptTouchEvent(MotionEvent ev) { 1247 /* 1248 * This method JUST determines whether we want to intercept the motion. 1249 * If we return true, onMotionEvent will be called and we do the actual 1250 * scrolling there. 1251 */ 1252 1253 final int action = ev.getAction() & MotionEventCompat.ACTION_MASK; 1254 1255 // Always take care of the touch gesture being complete. 1256 if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { 1257 // Release the drag. 1258 if (DEBUG) Log.v(TAG, "Intercept done!"); 1259 mIsBeingDragged = false; 1260 mIsUnableToDrag = false; 1261 mActivePointerId = INVALID_POINTER; 1262 if (mVelocityTracker != null) { 1263 mVelocityTracker.recycle(); 1264 mVelocityTracker = null; 1265 } 1266 return false; 1267 } 1268 1269 // Nothing more to do here if we have decided whether or not we 1270 // are dragging. 1271 if (action != MotionEvent.ACTION_DOWN) { 1272 if (mIsBeingDragged) { 1273 if (DEBUG) Log.v(TAG, "Intercept returning true!"); 1274 return true; 1275 } 1276 if (mIsUnableToDrag) { 1277 if (DEBUG) Log.v(TAG, "Intercept returning false!"); 1278 return false; 1279 } 1280 } 1281 1282 switch (action) { 1283 case MotionEvent.ACTION_MOVE: { 1284 /* 1285 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 1286 * whether the user has moved far enough from his original down touch. 1287 */ 1288 1289 /* 1290 * Locally do absolute value. mLastMotionY is set to the y value 1291 * of the down event. 1292 */ 1293 final int activePointerId = mActivePointerId; 1294 if (activePointerId == INVALID_POINTER) { 1295 // If we don't have a valid id, the touch down wasn't on content. 1296 break; 1297 } 1298 1299 final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId); 1300 final float x = MotionEventCompat.getX(ev, pointerIndex); 1301 final float dx = x - mLastMotionX; 1302 final float xDiff = Math.abs(dx); 1303 final float y = MotionEventCompat.getY(ev, pointerIndex); 1304 final float yDiff = Math.abs(y - mLastMotionY); 1305 final int scrollX = getScrollX(); 1306 if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff); 1307 1308 if (canScroll(this, false, (int) dx, (int) x, (int) y)) { 1309 // Nested view has scrollable area under this point. Let it be handled there. 1310 mInitialMotionX = mLastMotionX = x; 1311 mLastMotionY = y; 1312 return false; 1313 } 1314 if (xDiff > mTouchSlop && xDiff > yDiff) { 1315 if (DEBUG) Log.v(TAG, "Starting drag!"); 1316 mIsBeingDragged = true; 1317 setScrollState(SCROLL_STATE_DRAGGING); 1318 mLastMotionX = x; 1319 setScrollingCacheEnabled(true); 1320 } else { 1321 if (yDiff > mTouchSlop) { 1322 // The finger has moved enough in the vertical 1323 // direction to be counted as a drag... abort 1324 // any attempt to drag horizontally, to work correctly 1325 // with children that have scrolling containers. 1326 if (DEBUG) Log.v(TAG, "Starting unable to drag!"); 1327 mIsUnableToDrag = true; 1328 } 1329 } 1330 break; 1331 } 1332 1333 case MotionEvent.ACTION_DOWN: { 1334 /* 1335 * Remember location of down touch. 1336 * ACTION_DOWN always refers to pointer index 0. 1337 */ 1338 mLastMotionX = mInitialMotionX = ev.getX(); 1339 mLastMotionY = ev.getY(); 1340 mActivePointerId = MotionEventCompat.getPointerId(ev, 0); 1341 1342 if (mScrollState == SCROLL_STATE_SETTLING) { 1343 // Let the user 'catch' the pager as it animates. 1344 mIsBeingDragged = true; 1345 mIsUnableToDrag = false; 1346 setScrollState(SCROLL_STATE_DRAGGING); 1347 } else { 1348 completeScroll(); 1349 mIsBeingDragged = false; 1350 mIsUnableToDrag = false; 1351 } 1352 1353 if (DEBUG) Log.v(TAG, "Down at " + mLastMotionX + "," + mLastMotionY 1354 + " mIsBeingDragged=" + mIsBeingDragged 1355 + "mIsUnableToDrag=" + mIsUnableToDrag); 1356 break; 1357 } 1358 1359 case MotionEventCompat.ACTION_POINTER_UP: 1360 onSecondaryPointerUp(ev); 1361 break; 1362 } 1363 1364 if (!mIsBeingDragged) { 1365 // Track the velocity as long as we aren't dragging. 1366 // Once we start a real drag we will track in onTouchEvent. 1367 if (mVelocityTracker == null) { 1368 mVelocityTracker = VelocityTracker.obtain(); 1369 } 1370 mVelocityTracker.addMovement(ev); 1371 } 1372 1373 /* 1374 * The only time we want to intercept motion events is if we are in the 1375 * drag mode. 1376 */ 1377 return mIsBeingDragged; 1378 } 1379 1380 @Override 1381 public boolean onTouchEvent(MotionEvent ev) { 1382 if (mFakeDragging) { 1383 // A fake drag is in progress already, ignore this real one 1384 // but still eat the touch events. 1385 // (It is likely that the user is multi-touching the screen.) 1386 return true; 1387 } 1388 1389 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 1390 // Don't handle edge touches immediately -- they may actually belong to one of our 1391 // descendants. 1392 return false; 1393 } 1394 1395 if (mAdapter == null || mAdapter.getCount() == 0) { 1396 // Nothing to present or scroll; nothing to touch. 1397 return false; 1398 } 1399 1400 if (mVelocityTracker == null) { 1401 mVelocityTracker = VelocityTracker.obtain(); 1402 } 1403 mVelocityTracker.addMovement(ev); 1404 1405 final int action = ev.getAction(); 1406 boolean needsInvalidate = false; 1407 1408 switch (action & MotionEventCompat.ACTION_MASK) { 1409 case MotionEvent.ACTION_DOWN: { 1410 /* 1411 * If being flinged and user touches, stop the fling. isFinished 1412 * will be false if being flinged. 1413 */ 1414 completeScroll(); 1415 1416 // Remember where the motion event started 1417 mLastMotionX = mInitialMotionX = ev.getX(); 1418 mActivePointerId = MotionEventCompat.getPointerId(ev, 0); 1419 break; 1420 } 1421 case MotionEvent.ACTION_MOVE: 1422 if (!mIsBeingDragged) { 1423 final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 1424 final float x = MotionEventCompat.getX(ev, pointerIndex); 1425 final float xDiff = Math.abs(x - mLastMotionX); 1426 final float y = MotionEventCompat.getY(ev, pointerIndex); 1427 final float yDiff = Math.abs(y - mLastMotionY); 1428 if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff); 1429 if (xDiff > mTouchSlop && xDiff > yDiff) { 1430 if (DEBUG) Log.v(TAG, "Starting drag!"); 1431 mIsBeingDragged = true; 1432 mLastMotionX = x; 1433 setScrollState(SCROLL_STATE_DRAGGING); 1434 setScrollingCacheEnabled(true); 1435 } 1436 } 1437 if (mIsBeingDragged) { 1438 // Scroll to follow the motion event 1439 final int activePointerIndex = MotionEventCompat.findPointerIndex( 1440 ev, mActivePointerId); 1441 final float x = MotionEventCompat.getX(ev, activePointerIndex); 1442 final float deltaX = mLastMotionX - x; 1443 mLastMotionX = x; 1444 float oldScrollX = getScrollX(); 1445 float scrollX = oldScrollX + deltaX; 1446 final int width = getWidth(); 1447 final int widthWithMargin = width + mPageMargin; 1448 1449 final int lastItemIndex = mAdapter.getCount() - 1; 1450 final float leftBound = Math.max(0, (mCurItem - 1) * widthWithMargin); 1451 final float rightBound = 1452 Math.min(mCurItem + 1, lastItemIndex) * widthWithMargin; 1453 if (scrollX < leftBound) { 1454 if (leftBound == 0) { 1455 float over = -scrollX; 1456 needsInvalidate = mLeftEdge.onPull(over / width); 1457 } 1458 scrollX = leftBound; 1459 } else if (scrollX > rightBound) { 1460 if (rightBound == lastItemIndex * widthWithMargin) { 1461 float over = scrollX - rightBound; 1462 needsInvalidate = mRightEdge.onPull(over / width); 1463 } 1464 scrollX = rightBound; 1465 } 1466 // Don't lose the rounded component 1467 mLastMotionX += scrollX - (int) scrollX; 1468 scrollTo((int) scrollX, getScrollY()); 1469 pageScrolled((int) scrollX); 1470 } 1471 break; 1472 case MotionEvent.ACTION_UP: 1473 if (mIsBeingDragged) { 1474 final VelocityTracker velocityTracker = mVelocityTracker; 1475 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 1476 int initialVelocity = (int) VelocityTrackerCompat.getXVelocity( 1477 velocityTracker, mActivePointerId); 1478 mPopulatePending = true; 1479 final int widthWithMargin = getWidth() + mPageMargin; 1480 final int scrollX = getScrollX(); 1481 final int currentPage = scrollX / widthWithMargin; 1482 int nextPage = initialVelocity > 0 ? currentPage : currentPage + 1; 1483 setCurrentItemInternal(nextPage, true, true, initialVelocity); 1484 1485 mActivePointerId = INVALID_POINTER; 1486 endDrag(); 1487 needsInvalidate = mLeftEdge.onRelease() | mRightEdge.onRelease(); 1488 } 1489 break; 1490 case MotionEvent.ACTION_CANCEL: 1491 if (mIsBeingDragged) { 1492 setCurrentItemInternal(mCurItem, true, true); 1493 mActivePointerId = INVALID_POINTER; 1494 endDrag(); 1495 needsInvalidate = mLeftEdge.onRelease() | mRightEdge.onRelease(); 1496 } 1497 break; 1498 case MotionEventCompat.ACTION_POINTER_DOWN: { 1499 final int index = MotionEventCompat.getActionIndex(ev); 1500 final float x = MotionEventCompat.getX(ev, index); 1501 mLastMotionX = x; 1502 mActivePointerId = MotionEventCompat.getPointerId(ev, index); 1503 break; 1504 } 1505 case MotionEventCompat.ACTION_POINTER_UP: 1506 onSecondaryPointerUp(ev); 1507 mLastMotionX = MotionEventCompat.getX(ev, 1508 MotionEventCompat.findPointerIndex(ev, mActivePointerId)); 1509 break; 1510 } 1511 if (needsInvalidate) { 1512 invalidate(); 1513 } 1514 return true; 1515 } 1516 1517 @Override 1518 public void draw(Canvas canvas) { 1519 super.draw(canvas); 1520 boolean needsInvalidate = false; 1521 1522 final int overScrollMode = ViewCompat.getOverScrollMode(this); 1523 if (overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 1524 (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && 1525 mAdapter != null && mAdapter.getCount() > 1)) { 1526 if (!mLeftEdge.isFinished()) { 1527 final int restoreCount = canvas.save(); 1528 final int height = getHeight() - getPaddingTop() - getPaddingBottom(); 1529 1530 canvas.rotate(270); 1531 canvas.translate(-height + getPaddingTop(), 0); 1532 mLeftEdge.setSize(height, getWidth()); 1533 needsInvalidate |= mLeftEdge.draw(canvas); 1534 canvas.restoreToCount(restoreCount); 1535 } 1536 if (!mRightEdge.isFinished()) { 1537 final int restoreCount = canvas.save(); 1538 final int width = getWidth(); 1539 final int height = getHeight() - getPaddingTop() - getPaddingBottom(); 1540 final int itemCount = mAdapter != null ? mAdapter.getCount() : 1; 1541 1542 canvas.rotate(90); 1543 canvas.translate(-getPaddingTop(), 1544 -itemCount * (width + mPageMargin) + mPageMargin); 1545 mRightEdge.setSize(height, width); 1546 needsInvalidate |= mRightEdge.draw(canvas); 1547 canvas.restoreToCount(restoreCount); 1548 } 1549 } else { 1550 mLeftEdge.finish(); 1551 mRightEdge.finish(); 1552 } 1553 1554 if (needsInvalidate) { 1555 // Keep animating 1556 invalidate(); 1557 } 1558 } 1559 1560 @Override 1561 protected void onDraw(Canvas canvas) { 1562 super.onDraw(canvas); 1563 1564 // Draw the margin drawable if needed. 1565 if (mPageMargin > 0 && mMarginDrawable != null) { 1566 final int scrollX = getScrollX(); 1567 final int width = getWidth(); 1568 final int offset = scrollX % (width + mPageMargin); 1569 if (offset != 0) { 1570 // Pages fit completely when settled; we only need to draw when in between 1571 final int left = scrollX - offset + width; 1572 mMarginDrawable.setBounds(left, mTopPageBounds, left + mPageMargin, 1573 mBottomPageBounds); 1574 mMarginDrawable.draw(canvas); 1575 } 1576 } 1577 } 1578 1579 /** 1580 * Start a fake drag of the pager. 1581 * 1582 * <p>A fake drag can be useful if you want to synchronize the motion of the ViewPager 1583 * with the touch scrolling of another view, while still letting the ViewPager 1584 * control the snapping motion and fling behavior. (e.g. parallax-scrolling tabs.) 1585 * Call {@link #fakeDragBy(float)} to simulate the actual drag motion. Call 1586 * {@link #endFakeDrag()} to complete the fake drag and fling as necessary. 1587 * 1588 * <p>During a fake drag the ViewPager will ignore all touch events. If a real drag 1589 * is already in progress, this method will return false. 1590 * 1591 * @return true if the fake drag began successfully, false if it could not be started. 1592 * 1593 * @see #fakeDragBy(float) 1594 * @see #endFakeDrag() 1595 */ 1596 public boolean beginFakeDrag() { 1597 if (mIsBeingDragged) { 1598 return false; 1599 } 1600 mFakeDragging = true; 1601 setScrollState(SCROLL_STATE_DRAGGING); 1602 mInitialMotionX = mLastMotionX = 0; 1603 if (mVelocityTracker == null) { 1604 mVelocityTracker = VelocityTracker.obtain(); 1605 } else { 1606 mVelocityTracker.clear(); 1607 } 1608 final long time = SystemClock.uptimeMillis(); 1609 final MotionEvent ev = MotionEvent.obtain(time, time, MotionEvent.ACTION_DOWN, 0, 0, 0); 1610 mVelocityTracker.addMovement(ev); 1611 ev.recycle(); 1612 mFakeDragBeginTime = time; 1613 return true; 1614 } 1615 1616 /** 1617 * End a fake drag of the pager. 1618 * 1619 * @see #beginFakeDrag() 1620 * @see #fakeDragBy(float) 1621 */ 1622 public void endFakeDrag() { 1623 if (!mFakeDragging) { 1624 throw new IllegalStateException("No fake drag in progress. Call beginFakeDrag first."); 1625 } 1626 1627 final VelocityTracker velocityTracker = mVelocityTracker; 1628 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 1629 int initialVelocity = (int)VelocityTrackerCompat.getYVelocity( 1630 velocityTracker, mActivePointerId); 1631 mPopulatePending = true; 1632 if ((Math.abs(initialVelocity) > mMinimumVelocity) 1633 || Math.abs(mInitialMotionX-mLastMotionX) >= (getWidth()/3)) { 1634 if (mLastMotionX > mInitialMotionX) { 1635 setCurrentItemInternal(mCurItem-1, true, true); 1636 } else { 1637 setCurrentItemInternal(mCurItem+1, true, true); 1638 } 1639 } else { 1640 setCurrentItemInternal(mCurItem, true, true); 1641 } 1642 endDrag(); 1643 1644 mFakeDragging = false; 1645 } 1646 1647 /** 1648 * Fake drag by an offset in pixels. You must have called {@link #beginFakeDrag()} first. 1649 * 1650 * @param xOffset Offset in pixels to drag by. 1651 * @see #beginFakeDrag() 1652 * @see #endFakeDrag() 1653 */ 1654 public void fakeDragBy(float xOffset) { 1655 if (!mFakeDragging) { 1656 throw new IllegalStateException("No fake drag in progress. Call beginFakeDrag first."); 1657 } 1658 1659 mLastMotionX += xOffset; 1660 float scrollX = getScrollX() - xOffset; 1661 final int width = getWidth(); 1662 final int widthWithMargin = width + mPageMargin; 1663 1664 final float leftBound = Math.max(0, (mCurItem - 1) * widthWithMargin); 1665 final float rightBound = 1666 Math.min(mCurItem + 1, mAdapter.getCount() - 1) * widthWithMargin; 1667 if (scrollX < leftBound) { 1668 scrollX = leftBound; 1669 } else if (scrollX > rightBound) { 1670 scrollX = rightBound; 1671 } 1672 // Don't lose the rounded component 1673 mLastMotionX += scrollX - (int) scrollX; 1674 scrollTo((int) scrollX, getScrollY()); 1675 pageScrolled((int) scrollX); 1676 1677 // Synthesize an event for the VelocityTracker. 1678 final long time = SystemClock.uptimeMillis(); 1679 final MotionEvent ev = MotionEvent.obtain(mFakeDragBeginTime, time, MotionEvent.ACTION_MOVE, 1680 mLastMotionX, 0, 0); 1681 mVelocityTracker.addMovement(ev); 1682 ev.recycle(); 1683 } 1684 1685 /** 1686 * Returns true if a fake drag is in progress. 1687 * 1688 * @return true if currently in a fake drag, false otherwise. 1689 * 1690 * @see #beginFakeDrag() 1691 * @see #fakeDragBy(float) 1692 * @see #endFakeDrag() 1693 */ 1694 public boolean isFakeDragging() { 1695 return mFakeDragging; 1696 } 1697 1698 private void onSecondaryPointerUp(MotionEvent ev) { 1699 final int pointerIndex = MotionEventCompat.getActionIndex(ev); 1700 final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); 1701 if (pointerId == mActivePointerId) { 1702 // This was our active pointer going up. Choose a new 1703 // active pointer and adjust accordingly. 1704 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 1705 mLastMotionX = MotionEventCompat.getX(ev, newPointerIndex); 1706 mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); 1707 if (mVelocityTracker != null) { 1708 mVelocityTracker.clear(); 1709 } 1710 } 1711 } 1712 1713 private void endDrag() { 1714 mIsBeingDragged = false; 1715 mIsUnableToDrag = false; 1716 1717 if (mVelocityTracker != null) { 1718 mVelocityTracker.recycle(); 1719 mVelocityTracker = null; 1720 } 1721 } 1722 1723 private void setScrollingCacheEnabled(boolean enabled) { 1724 if (mScrollingCacheEnabled != enabled) { 1725 mScrollingCacheEnabled = enabled; 1726 if (USE_CACHE) { 1727 final int size = getChildCount(); 1728 for (int i = 0; i < size; ++i) { 1729 final View child = getChildAt(i); 1730 if (child.getVisibility() != GONE) { 1731 child.setDrawingCacheEnabled(enabled); 1732 } 1733 } 1734 } 1735 } 1736 } 1737 1738 /** 1739 * Tests scrollability within child views of v given a delta of dx. 1740 * 1741 * @param v View to test for horizontal scrollability 1742 * @param checkV Whether the view v passed should itself be checked for scrollability (true), 1743 * or just its children (false). 1744 * @param dx Delta scrolled in pixels 1745 * @param x X coordinate of the active touch point 1746 * @param y Y coordinate of the active touch point 1747 * @return true if child views of v can be scrolled by delta of dx. 1748 */ 1749 protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) { 1750 if (v instanceof ViewGroup) { 1751 final ViewGroup group = (ViewGroup) v; 1752 final int scrollX = v.getScrollX(); 1753 final int scrollY = v.getScrollY(); 1754 final int count = group.getChildCount(); 1755 // Count backwards - let topmost views consume scroll distance first. 1756 for (int i = count - 1; i >= 0; i--) { 1757 // TODO: Add versioned support here for transformed views. 1758 // This will not work for transformed views in Honeycomb+ 1759 final View child = group.getChildAt(i); 1760 if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && 1761 y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && 1762 canScroll(child, true, dx, x + scrollX - child.getLeft(), 1763 y + scrollY - child.getTop())) { 1764 return true; 1765 } 1766 } 1767 } 1768 1769 return checkV && ViewCompat.canScrollHorizontally(v, -dx); 1770 } 1771 1772 @Override 1773 public boolean dispatchKeyEvent(KeyEvent event) { 1774 // Let the focused view and/or our descendants get the key first 1775 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 1776 } 1777 1778 /** 1779 * You can call this function yourself to have the scroll view perform 1780 * scrolling from a key event, just as if the event had been dispatched to 1781 * it by the view hierarchy. 1782 * 1783 * @param event The key event to execute. 1784 * @return Return true if the event was handled, else false. 1785 */ 1786 public boolean executeKeyEvent(KeyEvent event) { 1787 boolean handled = false; 1788 if (event.getAction() == KeyEvent.ACTION_DOWN) { 1789 switch (event.getKeyCode()) { 1790 case KeyEvent.KEYCODE_DPAD_LEFT: 1791 handled = arrowScroll(FOCUS_LEFT); 1792 break; 1793 case KeyEvent.KEYCODE_DPAD_RIGHT: 1794 handled = arrowScroll(FOCUS_RIGHT); 1795 break; 1796 case KeyEvent.KEYCODE_TAB: 1797 if (KeyEventCompat.hasNoModifiers(event)) { 1798 handled = arrowScroll(FOCUS_FORWARD); 1799 } else if (KeyEventCompat.hasModifiers(event, KeyEvent.META_SHIFT_ON)) { 1800 handled = arrowScroll(FOCUS_BACKWARD); 1801 } 1802 break; 1803 } 1804 } 1805 return handled; 1806 } 1807 1808 public boolean arrowScroll(int direction) { 1809 View currentFocused = findFocus(); 1810 if (currentFocused == this) currentFocused = null; 1811 1812 boolean handled = false; 1813 1814 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, 1815 direction); 1816 if (nextFocused != null && nextFocused != currentFocused) { 1817 if (direction == View.FOCUS_LEFT) { 1818 // If there is nothing to the left, or this is causing us to 1819 // jump to the right, then what we really want to do is page left. 1820 if (currentFocused != null && nextFocused.getLeft() >= currentFocused.getLeft()) { 1821 handled = pageLeft(); 1822 } else { 1823 handled = nextFocused.requestFocus(); 1824 } 1825 } else if (direction == View.FOCUS_RIGHT) { 1826 // If there is nothing to the right, or this is causing us to 1827 // jump to the left, then what we really want to do is page right. 1828 if (currentFocused != null && nextFocused.getLeft() <= currentFocused.getLeft()) { 1829 handled = pageRight(); 1830 } else { 1831 handled = nextFocused.requestFocus(); 1832 } 1833 } 1834 } else if (direction == FOCUS_LEFT || direction == FOCUS_BACKWARD) { 1835 // Trying to move left and nothing there; try to page. 1836 handled = pageLeft(); 1837 } else if (direction == FOCUS_RIGHT || direction == FOCUS_FORWARD) { 1838 // Trying to move right and nothing there; try to page. 1839 handled = pageRight(); 1840 } 1841 if (handled) { 1842 playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction)); 1843 } 1844 return handled; 1845 } 1846 1847 boolean pageLeft() { 1848 if (mCurItem > 0) { 1849 setCurrentItem(mCurItem-1, true); 1850 return true; 1851 } 1852 return false; 1853 } 1854 1855 boolean pageRight() { 1856 if (mAdapter != null && mCurItem < (mAdapter.getCount()-1)) { 1857 setCurrentItem(mCurItem+1, true); 1858 return true; 1859 } 1860 return false; 1861 } 1862 1863 /** 1864 * We only want the current page that is being shown to be focusable. 1865 */ 1866 @Override 1867 public void addFocusables(ArrayList<View> views, int direction, int focusableMode) { 1868 final int focusableCount = views.size(); 1869 1870 final int descendantFocusability = getDescendantFocusability(); 1871 1872 if (descendantFocusability != FOCUS_BLOCK_DESCENDANTS) { 1873 for (int i = 0; i < getChildCount(); i++) { 1874 final View child = getChildAt(i); 1875 if (child.getVisibility() == VISIBLE) { 1876 ItemInfo ii = infoForChild(child); 1877 if (ii != null && ii.position == mCurItem) { 1878 child.addFocusables(views, direction, focusableMode); 1879 } 1880 } 1881 } 1882 } 1883 1884 // we add ourselves (if focusable) in all cases except for when we are 1885 // FOCUS_AFTER_DESCENDANTS and there are some descendants focusable. this is 1886 // to avoid the focus search finding layouts when a more precise search 1887 // among the focusable children would be more interesting. 1888 if ( 1889 descendantFocusability != FOCUS_AFTER_DESCENDANTS || 1890 // No focusable descendants 1891 (focusableCount == views.size())) { 1892 // Note that we can't call the superclass here, because it will 1893 // add all views in. So we need to do the same thing View does. 1894 if (!isFocusable()) { 1895 return; 1896 } 1897 if ((focusableMode & FOCUSABLES_TOUCH_MODE) == FOCUSABLES_TOUCH_MODE && 1898 isInTouchMode() && !isFocusableInTouchMode()) { 1899 return; 1900 } 1901 if (views != null) { 1902 views.add(this); 1903 } 1904 } 1905 } 1906 1907 /** 1908 * We only want the current page that is being shown to be touchable. 1909 */ 1910 @Override 1911 public void addTouchables(ArrayList<View> views) { 1912 // Note that we don't call super.addTouchables(), which means that 1913 // we don't call View.addTouchables(). This is okay because a ViewPager 1914 // is itself not touchable. 1915 for (int i = 0; i < getChildCount(); i++) { 1916 final View child = getChildAt(i); 1917 if (child.getVisibility() == VISIBLE) { 1918 ItemInfo ii = infoForChild(child); 1919 if (ii != null && ii.position == mCurItem) { 1920 child.addTouchables(views); 1921 } 1922 } 1923 } 1924 } 1925 1926 /** 1927 * We only want the current page that is being shown to be focusable. 1928 */ 1929 @Override 1930 protected boolean onRequestFocusInDescendants(int direction, 1931 Rect previouslyFocusedRect) { 1932 int index; 1933 int increment; 1934 int end; 1935 int count = getChildCount(); 1936 if ((direction & FOCUS_FORWARD) != 0) { 1937 index = 0; 1938 increment = 1; 1939 end = count; 1940 } else { 1941 index = count - 1; 1942 increment = -1; 1943 end = -1; 1944 } 1945 for (int i = index; i != end; i += increment) { 1946 View child = getChildAt(i); 1947 if (child.getVisibility() == VISIBLE) { 1948 ItemInfo ii = infoForChild(child); 1949 if (ii != null && ii.position == mCurItem) { 1950 if (child.requestFocus(direction, previouslyFocusedRect)) { 1951 return true; 1952 } 1953 } 1954 } 1955 } 1956 return false; 1957 } 1958 1959 @Override 1960 public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) { 1961 // ViewPagers should only report accessibility info for the current page, 1962 // otherwise things get very confusing. 1963 1964 // TODO: Should this note something about the paging container? 1965 1966 final int childCount = getChildCount(); 1967 for (int i = 0; i < childCount; i++) { 1968 final View child = getChildAt(i); 1969 if (child.getVisibility() == VISIBLE) { 1970 final ItemInfo ii = infoForChild(child); 1971 if (ii != null && ii.position == mCurItem && 1972 child.dispatchPopulateAccessibilityEvent(event)) { 1973 return true; 1974 } 1975 } 1976 } 1977 1978 return false; 1979 } 1980 1981 @Override 1982 protected ViewGroup.LayoutParams generateDefaultLayoutParams() { 1983 return new LayoutParams(); 1984 } 1985 1986 @Override 1987 protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { 1988 return generateDefaultLayoutParams(); 1989 } 1990 1991 @Override 1992 protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { 1993 return p instanceof LayoutParams && super.checkLayoutParams(p); 1994 } 1995 1996 @Override 1997 public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) { 1998 return new LayoutParams(getContext(), attrs); 1999 } 2000 2001 private class PagerObserver extends DataSetObserver { 2002 @Override 2003 public void onChanged() { 2004 dataSetChanged(); 2005 } 2006 @Override 2007 public void onInvalidated() { 2008 dataSetChanged(); 2009 } 2010 } 2011 2012 public static class LayoutParams extends ViewGroup.LayoutParams { 2013 /** 2014 * true if this view is a decoration on the pager itself and not 2015 * a view supplied by the adapter. 2016 */ 2017 public boolean isDecor; 2018 2019 public int gravity; 2020 2021 public LayoutParams() { 2022 super(FILL_PARENT, FILL_PARENT); 2023 } 2024 2025 public LayoutParams(Context context, AttributeSet attrs) { 2026 super(context, attrs); 2027 2028 final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS); 2029 gravity = a.getInteger(0, Gravity.NO_GRAVITY); 2030 a.recycle(); 2031 } 2032 } 2033} 2034