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 com.android.internal.R; 20 21import android.content.Context; 22import android.content.res.TypedArray; 23import android.graphics.Canvas; 24import android.graphics.Rect; 25import android.os.Bundle; 26import android.os.StrictMode; 27import android.util.AttributeSet; 28import android.view.FocusFinder; 29import android.view.InputDevice; 30import android.view.KeyEvent; 31import android.view.MotionEvent; 32import android.view.VelocityTracker; 33import android.view.View; 34import android.view.ViewConfiguration; 35import android.view.ViewDebug; 36import android.view.ViewGroup; 37import android.view.ViewParent; 38import android.view.accessibility.AccessibilityEvent; 39import android.view.accessibility.AccessibilityNodeInfo; 40import android.view.animation.AnimationUtils; 41 42import java.util.List; 43 44/** 45 * Layout container for a view hierarchy that can be scrolled by the user, 46 * allowing it to be larger than the physical display. A ScrollView 47 * is a {@link FrameLayout}, meaning you should place one child in it 48 * containing the entire contents to scroll; this child may itself be a layout 49 * manager with a complex hierarchy of objects. A child that is often used 50 * is a {@link LinearLayout} in a vertical orientation, presenting a vertical 51 * array of top-level items that the user can scroll through. 52 * <p>You should never use a ScrollView with a {@link ListView}, because 53 * ListView takes care of its own vertical scrolling. Most importantly, doing this 54 * defeats all of the important optimizations in ListView for dealing with 55 * large lists, since it effectively forces the ListView to display its entire 56 * list of items to fill up the infinite container supplied by ScrollView. 57 * <p>The {@link TextView} class also 58 * takes care of its own scrolling, so does not require a ScrollView, but 59 * using the two together is possible to achieve the effect of a text view 60 * within a larger container. 61 * 62 * <p>ScrollView only supports vertical scrolling. For horizontal scrolling, 63 * use {@link HorizontalScrollView}. 64 * 65 * @attr ref android.R.styleable#ScrollView_fillViewport 66 */ 67public class ScrollView extends FrameLayout { 68 static final int ANIMATED_SCROLL_GAP = 250; 69 70 static final float MAX_SCROLL_FACTOR = 0.5f; 71 72 private long mLastScroll; 73 74 private final Rect mTempRect = new Rect(); 75 private OverScroller mScroller; 76 private EdgeEffect mEdgeGlowTop; 77 private EdgeEffect mEdgeGlowBottom; 78 79 /** 80 * Position of the last motion event. 81 */ 82 private int mLastMotionY; 83 84 /** 85 * True when the layout has changed but the traversal has not come through yet. 86 * Ideally the view hierarchy would keep track of this for us. 87 */ 88 private boolean mIsLayoutDirty = true; 89 90 /** 91 * The child to give focus to in the event that a child has requested focus while the 92 * layout is dirty. This prevents the scroll from being wrong if the child has not been 93 * laid out before requesting focus. 94 */ 95 private View mChildToScrollTo = null; 96 97 /** 98 * True if the user is currently dragging this ScrollView around. This is 99 * not the same as 'is being flinged', which can be checked by 100 * mScroller.isFinished() (flinging begins when the user lifts his finger). 101 */ 102 private boolean mIsBeingDragged = false; 103 104 /** 105 * Determines speed during touch scrolling 106 */ 107 private VelocityTracker mVelocityTracker; 108 109 /** 110 * When set to true, the scroll view measure its child to make it fill the currently 111 * visible area. 112 */ 113 @ViewDebug.ExportedProperty(category = "layout") 114 private boolean mFillViewport; 115 116 /** 117 * Whether arrow scrolling is animated. 118 */ 119 private boolean mSmoothScrollingEnabled = true; 120 121 private int mTouchSlop; 122 private int mMinimumVelocity; 123 private int mMaximumVelocity; 124 125 private int mOverscrollDistance; 126 private int mOverflingDistance; 127 128 /** 129 * ID of the active pointer. This is used to retain consistency during 130 * drags/flings if multiple pointers are used. 131 */ 132 private int mActivePointerId = INVALID_POINTER; 133 134 /** 135 * The StrictMode "critical time span" objects to catch animation 136 * stutters. Non-null when a time-sensitive animation is 137 * in-flight. Must call finish() on them when done animating. 138 * These are no-ops on user builds. 139 */ 140 private StrictMode.Span mScrollStrictSpan = null; // aka "drag" 141 private StrictMode.Span mFlingStrictSpan = null; 142 143 /** 144 * Sentinel value for no current active pointer. 145 * Used by {@link #mActivePointerId}. 146 */ 147 private static final int INVALID_POINTER = -1; 148 149 public ScrollView(Context context) { 150 this(context, null); 151 } 152 153 public ScrollView(Context context, AttributeSet attrs) { 154 this(context, attrs, com.android.internal.R.attr.scrollViewStyle); 155 } 156 157 public ScrollView(Context context, AttributeSet attrs, int defStyle) { 158 super(context, attrs, defStyle); 159 initScrollView(); 160 161 TypedArray a = 162 context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ScrollView, defStyle, 0); 163 164 setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false)); 165 166 a.recycle(); 167 } 168 169 @Override 170 public boolean shouldDelayChildPressedState() { 171 return true; 172 } 173 174 @Override 175 protected float getTopFadingEdgeStrength() { 176 if (getChildCount() == 0) { 177 return 0.0f; 178 } 179 180 final int length = getVerticalFadingEdgeLength(); 181 if (mScrollY < length) { 182 return mScrollY / (float) length; 183 } 184 185 return 1.0f; 186 } 187 188 @Override 189 protected float getBottomFadingEdgeStrength() { 190 if (getChildCount() == 0) { 191 return 0.0f; 192 } 193 194 final int length = getVerticalFadingEdgeLength(); 195 final int bottomEdge = getHeight() - mPaddingBottom; 196 final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge; 197 if (span < length) { 198 return span / (float) length; 199 } 200 201 return 1.0f; 202 } 203 204 /** 205 * @return The maximum amount this scroll view will scroll in response to 206 * an arrow event. 207 */ 208 public int getMaxScrollAmount() { 209 return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop)); 210 } 211 212 213 private void initScrollView() { 214 mScroller = new OverScroller(getContext()); 215 setFocusable(true); 216 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 217 setWillNotDraw(false); 218 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 219 mTouchSlop = configuration.getScaledTouchSlop(); 220 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 221 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 222 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 223 mOverflingDistance = configuration.getScaledOverflingDistance(); 224 } 225 226 @Override 227 public void addView(View child) { 228 if (getChildCount() > 0) { 229 throw new IllegalStateException("ScrollView can host only one direct child"); 230 } 231 232 super.addView(child); 233 } 234 235 @Override 236 public void addView(View child, int index) { 237 if (getChildCount() > 0) { 238 throw new IllegalStateException("ScrollView can host only one direct child"); 239 } 240 241 super.addView(child, index); 242 } 243 244 @Override 245 public void addView(View child, ViewGroup.LayoutParams params) { 246 if (getChildCount() > 0) { 247 throw new IllegalStateException("ScrollView can host only one direct child"); 248 } 249 250 super.addView(child, params); 251 } 252 253 @Override 254 public void addView(View child, int index, ViewGroup.LayoutParams params) { 255 if (getChildCount() > 0) { 256 throw new IllegalStateException("ScrollView can host only one direct child"); 257 } 258 259 super.addView(child, index, params); 260 } 261 262 /** 263 * @return Returns true this ScrollView can be scrolled 264 */ 265 private boolean canScroll() { 266 View child = getChildAt(0); 267 if (child != null) { 268 int childHeight = child.getHeight(); 269 return getHeight() < childHeight + mPaddingTop + mPaddingBottom; 270 } 271 return false; 272 } 273 274 /** 275 * Indicates whether this ScrollView's content is stretched to fill the viewport. 276 * 277 * @return True if the content fills the viewport, false otherwise. 278 * 279 * @attr ref android.R.styleable#ScrollView_fillViewport 280 */ 281 public boolean isFillViewport() { 282 return mFillViewport; 283 } 284 285 /** 286 * Indicates this ScrollView whether it should stretch its content height to fill 287 * the viewport or not. 288 * 289 * @param fillViewport True to stretch the content's height to the viewport's 290 * boundaries, false otherwise. 291 * 292 * @attr ref android.R.styleable#ScrollView_fillViewport 293 */ 294 public void setFillViewport(boolean fillViewport) { 295 if (fillViewport != mFillViewport) { 296 mFillViewport = fillViewport; 297 requestLayout(); 298 } 299 } 300 301 /** 302 * @return Whether arrow scrolling will animate its transition. 303 */ 304 public boolean isSmoothScrollingEnabled() { 305 return mSmoothScrollingEnabled; 306 } 307 308 /** 309 * Set whether arrow scrolling will animate its transition. 310 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 311 */ 312 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 313 mSmoothScrollingEnabled = smoothScrollingEnabled; 314 } 315 316 @Override 317 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 318 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 319 320 if (!mFillViewport) { 321 return; 322 } 323 324 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 325 if (heightMode == MeasureSpec.UNSPECIFIED) { 326 return; 327 } 328 329 if (getChildCount() > 0) { 330 final View child = getChildAt(0); 331 int height = getMeasuredHeight(); 332 if (child.getMeasuredHeight() < height) { 333 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 334 335 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 336 mPaddingLeft + mPaddingRight, lp.width); 337 height -= mPaddingTop; 338 height -= mPaddingBottom; 339 int childHeightMeasureSpec = 340 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 341 342 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 343 } 344 } 345 } 346 347 @Override 348 public boolean dispatchKeyEvent(KeyEvent event) { 349 // Let the focused view and/or our descendants get the key first 350 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 351 } 352 353 /** 354 * You can call this function yourself to have the scroll view perform 355 * scrolling from a key event, just as if the event had been dispatched to 356 * it by the view hierarchy. 357 * 358 * @param event The key event to execute. 359 * @return Return true if the event was handled, else false. 360 */ 361 public boolean executeKeyEvent(KeyEvent event) { 362 mTempRect.setEmpty(); 363 364 if (!canScroll()) { 365 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 366 View currentFocused = findFocus(); 367 if (currentFocused == this) currentFocused = null; 368 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 369 currentFocused, View.FOCUS_DOWN); 370 return nextFocused != null 371 && nextFocused != this 372 && nextFocused.requestFocus(View.FOCUS_DOWN); 373 } 374 return false; 375 } 376 377 boolean handled = false; 378 if (event.getAction() == KeyEvent.ACTION_DOWN) { 379 switch (event.getKeyCode()) { 380 case KeyEvent.KEYCODE_DPAD_UP: 381 if (!event.isAltPressed()) { 382 handled = arrowScroll(View.FOCUS_UP); 383 } else { 384 handled = fullScroll(View.FOCUS_UP); 385 } 386 break; 387 case KeyEvent.KEYCODE_DPAD_DOWN: 388 if (!event.isAltPressed()) { 389 handled = arrowScroll(View.FOCUS_DOWN); 390 } else { 391 handled = fullScroll(View.FOCUS_DOWN); 392 } 393 break; 394 case KeyEvent.KEYCODE_SPACE: 395 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 396 break; 397 } 398 } 399 400 return handled; 401 } 402 403 private boolean inChild(int x, int y) { 404 if (getChildCount() > 0) { 405 final int scrollY = mScrollY; 406 final View child = getChildAt(0); 407 return !(y < child.getTop() - scrollY 408 || y >= child.getBottom() - scrollY 409 || x < child.getLeft() 410 || x >= child.getRight()); 411 } 412 return false; 413 } 414 415 private void initOrResetVelocityTracker() { 416 if (mVelocityTracker == null) { 417 mVelocityTracker = VelocityTracker.obtain(); 418 } else { 419 mVelocityTracker.clear(); 420 } 421 } 422 423 private void initVelocityTrackerIfNotExists() { 424 if (mVelocityTracker == null) { 425 mVelocityTracker = VelocityTracker.obtain(); 426 } 427 } 428 429 private void recycleVelocityTracker() { 430 if (mVelocityTracker != null) { 431 mVelocityTracker.recycle(); 432 mVelocityTracker = null; 433 } 434 } 435 436 @Override 437 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 438 if (disallowIntercept) { 439 recycleVelocityTracker(); 440 } 441 super.requestDisallowInterceptTouchEvent(disallowIntercept); 442 } 443 444 445 @Override 446 public boolean onInterceptTouchEvent(MotionEvent ev) { 447 /* 448 * This method JUST determines whether we want to intercept the motion. 449 * If we return true, onMotionEvent will be called and we do the actual 450 * scrolling there. 451 */ 452 453 /* 454 * Shortcut the most recurring case: the user is in the dragging 455 * state and he is moving his finger. We want to intercept this 456 * motion. 457 */ 458 final int action = ev.getAction(); 459 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 460 return true; 461 } 462 463 switch (action & MotionEvent.ACTION_MASK) { 464 case MotionEvent.ACTION_MOVE: { 465 /* 466 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 467 * whether the user has moved far enough from his original down touch. 468 */ 469 470 /* 471 * Locally do absolute value. mLastMotionY is set to the y value 472 * of the down event. 473 */ 474 final int activePointerId = mActivePointerId; 475 if (activePointerId == INVALID_POINTER) { 476 // If we don't have a valid id, the touch down wasn't on content. 477 break; 478 } 479 480 final int pointerIndex = ev.findPointerIndex(activePointerId); 481 final int y = (int) ev.getY(pointerIndex); 482 final int yDiff = Math.abs(y - mLastMotionY); 483 if (yDiff > mTouchSlop) { 484 mIsBeingDragged = true; 485 mLastMotionY = y; 486 initVelocityTrackerIfNotExists(); 487 mVelocityTracker.addMovement(ev); 488 if (mScrollStrictSpan == null) { 489 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 490 } 491 final ViewParent parent = getParent(); 492 if (parent != null) { 493 parent.requestDisallowInterceptTouchEvent(true); 494 } 495 } 496 break; 497 } 498 499 case MotionEvent.ACTION_DOWN: { 500 final int y = (int) ev.getY(); 501 if (!inChild((int) ev.getX(), (int) y)) { 502 mIsBeingDragged = false; 503 recycleVelocityTracker(); 504 break; 505 } 506 507 /* 508 * Remember location of down touch. 509 * ACTION_DOWN always refers to pointer index 0. 510 */ 511 mLastMotionY = y; 512 mActivePointerId = ev.getPointerId(0); 513 514 initOrResetVelocityTracker(); 515 mVelocityTracker.addMovement(ev); 516 /* 517 * If being flinged and user touches the screen, initiate drag; 518 * otherwise don't. mScroller.isFinished should be false when 519 * being flinged. 520 */ 521 mIsBeingDragged = !mScroller.isFinished(); 522 if (mIsBeingDragged && mScrollStrictSpan == null) { 523 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 524 } 525 break; 526 } 527 528 case MotionEvent.ACTION_CANCEL: 529 case MotionEvent.ACTION_UP: 530 /* Release the drag */ 531 mIsBeingDragged = false; 532 mActivePointerId = INVALID_POINTER; 533 recycleVelocityTracker(); 534 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 535 postInvalidateOnAnimation(); 536 } 537 break; 538 case MotionEvent.ACTION_POINTER_UP: 539 onSecondaryPointerUp(ev); 540 break; 541 } 542 543 /* 544 * The only time we want to intercept motion events is if we are in the 545 * drag mode. 546 */ 547 return mIsBeingDragged; 548 } 549 550 @Override 551 public boolean onTouchEvent(MotionEvent ev) { 552 initVelocityTrackerIfNotExists(); 553 mVelocityTracker.addMovement(ev); 554 555 final int action = ev.getAction(); 556 557 switch (action & MotionEvent.ACTION_MASK) { 558 case MotionEvent.ACTION_DOWN: { 559 if (getChildCount() == 0) { 560 return false; 561 } 562 if ((mIsBeingDragged = !mScroller.isFinished())) { 563 final ViewParent parent = getParent(); 564 if (parent != null) { 565 parent.requestDisallowInterceptTouchEvent(true); 566 } 567 } 568 569 /* 570 * If being flinged and user touches, stop the fling. isFinished 571 * will be false if being flinged. 572 */ 573 if (!mScroller.isFinished()) { 574 mScroller.abortAnimation(); 575 if (mFlingStrictSpan != null) { 576 mFlingStrictSpan.finish(); 577 mFlingStrictSpan = null; 578 } 579 } 580 581 // Remember where the motion event started 582 mLastMotionY = (int) ev.getY(); 583 mActivePointerId = ev.getPointerId(0); 584 break; 585 } 586 case MotionEvent.ACTION_MOVE: 587 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 588 final int y = (int) ev.getY(activePointerIndex); 589 int deltaY = mLastMotionY - y; 590 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 591 final ViewParent parent = getParent(); 592 if (parent != null) { 593 parent.requestDisallowInterceptTouchEvent(true); 594 } 595 mIsBeingDragged = true; 596 if (deltaY > 0) { 597 deltaY -= mTouchSlop; 598 } else { 599 deltaY += mTouchSlop; 600 } 601 } 602 if (mIsBeingDragged) { 603 // Scroll to follow the motion event 604 mLastMotionY = y; 605 606 final int oldX = mScrollX; 607 final int oldY = mScrollY; 608 final int range = getScrollRange(); 609 final int overscrollMode = getOverScrollMode(); 610 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 611 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 612 613 if (overScrollBy(0, deltaY, 0, mScrollY, 614 0, range, 0, mOverscrollDistance, true)) { 615 // Break our velocity if we hit a scroll barrier. 616 mVelocityTracker.clear(); 617 } 618 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 619 620 if (canOverscroll) { 621 final int pulledToY = oldY + deltaY; 622 if (pulledToY < 0) { 623 mEdgeGlowTop.onPull((float) deltaY / getHeight()); 624 if (!mEdgeGlowBottom.isFinished()) { 625 mEdgeGlowBottom.onRelease(); 626 } 627 } else if (pulledToY > range) { 628 mEdgeGlowBottom.onPull((float) deltaY / getHeight()); 629 if (!mEdgeGlowTop.isFinished()) { 630 mEdgeGlowTop.onRelease(); 631 } 632 } 633 if (mEdgeGlowTop != null 634 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 635 postInvalidateOnAnimation(); 636 } 637 } 638 } 639 break; 640 case MotionEvent.ACTION_UP: 641 if (mIsBeingDragged) { 642 final VelocityTracker velocityTracker = mVelocityTracker; 643 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 644 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 645 646 if (getChildCount() > 0) { 647 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 648 fling(-initialVelocity); 649 } else { 650 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, 651 getScrollRange())) { 652 postInvalidateOnAnimation(); 653 } 654 } 655 } 656 657 mActivePointerId = INVALID_POINTER; 658 endDrag(); 659 } 660 break; 661 case MotionEvent.ACTION_CANCEL: 662 if (mIsBeingDragged && getChildCount() > 0) { 663 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 664 postInvalidateOnAnimation(); 665 } 666 mActivePointerId = INVALID_POINTER; 667 endDrag(); 668 } 669 break; 670 case MotionEvent.ACTION_POINTER_DOWN: { 671 final int index = ev.getActionIndex(); 672 mLastMotionY = (int) ev.getY(index); 673 mActivePointerId = ev.getPointerId(index); 674 break; 675 } 676 case MotionEvent.ACTION_POINTER_UP: 677 onSecondaryPointerUp(ev); 678 mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId)); 679 break; 680 } 681 return true; 682 } 683 684 private void onSecondaryPointerUp(MotionEvent ev) { 685 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 686 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 687 final int pointerId = ev.getPointerId(pointerIndex); 688 if (pointerId == mActivePointerId) { 689 // This was our active pointer going up. Choose a new 690 // active pointer and adjust accordingly. 691 // TODO: Make this decision more intelligent. 692 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 693 mLastMotionY = (int) ev.getY(newPointerIndex); 694 mActivePointerId = ev.getPointerId(newPointerIndex); 695 if (mVelocityTracker != null) { 696 mVelocityTracker.clear(); 697 } 698 } 699 } 700 701 @Override 702 public boolean onGenericMotionEvent(MotionEvent event) { 703 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 704 switch (event.getAction()) { 705 case MotionEvent.ACTION_SCROLL: { 706 if (!mIsBeingDragged) { 707 final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); 708 if (vscroll != 0) { 709 final int delta = (int) (vscroll * getVerticalScrollFactor()); 710 final int range = getScrollRange(); 711 int oldScrollY = mScrollY; 712 int newScrollY = oldScrollY - delta; 713 if (newScrollY < 0) { 714 newScrollY = 0; 715 } else if (newScrollY > range) { 716 newScrollY = range; 717 } 718 if (newScrollY != oldScrollY) { 719 super.scrollTo(mScrollX, newScrollY); 720 return true; 721 } 722 } 723 } 724 } 725 } 726 } 727 return super.onGenericMotionEvent(event); 728 } 729 730 @Override 731 protected void onOverScrolled(int scrollX, int scrollY, 732 boolean clampedX, boolean clampedY) { 733 // Treat animating scrolls differently; see #computeScroll() for why. 734 if (!mScroller.isFinished()) { 735 mScrollX = scrollX; 736 mScrollY = scrollY; 737 invalidateParentIfNeeded(); 738 if (clampedY) { 739 mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 740 } 741 } else { 742 super.scrollTo(scrollX, scrollY); 743 } 744 745 awakenScrollBars(); 746 } 747 748 @Override 749 public boolean performAccessibilityAction(int action, Bundle arguments) { 750 if (super.performAccessibilityAction(action, arguments)) { 751 return true; 752 } 753 if (!isEnabled()) { 754 return false; 755 } 756 switch (action) { 757 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 758 final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop; 759 final int targetScrollY = Math.min(mScrollY + viewportHeight, getScrollRange()); 760 if (targetScrollY != mScrollY) { 761 smoothScrollTo(0, targetScrollY); 762 return true; 763 } 764 } return false; 765 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 766 final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop; 767 final int targetScrollY = Math.max(mScrollY - viewportHeight, 0); 768 if (targetScrollY != mScrollY) { 769 smoothScrollTo(0, targetScrollY); 770 return true; 771 } 772 } return false; 773 } 774 return false; 775 } 776 777 @Override 778 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 779 super.onInitializeAccessibilityNodeInfo(info); 780 info.setClassName(ScrollView.class.getName()); 781 if (isEnabled()) { 782 final int scrollRange = getScrollRange(); 783 if (scrollRange > 0) { 784 info.setScrollable(true); 785 if (mScrollY > 0) { 786 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 787 } 788 if (mScrollY < scrollRange) { 789 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 790 } 791 } 792 } 793 } 794 795 @Override 796 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 797 super.onInitializeAccessibilityEvent(event); 798 event.setClassName(ScrollView.class.getName()); 799 final boolean scrollable = getScrollRange() > 0; 800 event.setScrollable(scrollable); 801 event.setScrollX(mScrollX); 802 event.setScrollY(mScrollY); 803 event.setMaxScrollX(mScrollX); 804 event.setMaxScrollY(getScrollRange()); 805 } 806 807 private int getScrollRange() { 808 int scrollRange = 0; 809 if (getChildCount() > 0) { 810 View child = getChildAt(0); 811 scrollRange = Math.max(0, 812 child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop)); 813 } 814 return scrollRange; 815 } 816 817 /** 818 * <p> 819 * Finds the next focusable component that fits in the specified bounds. 820 * </p> 821 * 822 * @param topFocus look for a candidate is the one at the top of the bounds 823 * if topFocus is true, or at the bottom of the bounds if topFocus is 824 * false 825 * @param top the top offset of the bounds in which a focusable must be 826 * found 827 * @param bottom the bottom offset of the bounds in which a focusable must 828 * be found 829 * @return the next focusable component in the bounds or null if none can 830 * be found 831 */ 832 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 833 834 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 835 View focusCandidate = null; 836 837 /* 838 * A fully contained focusable is one where its top is below the bound's 839 * top, and its bottom is above the bound's bottom. A partially 840 * contained focusable is one where some part of it is within the 841 * bounds, but it also has some part that is not within bounds. A fully contained 842 * focusable is preferred to a partially contained focusable. 843 */ 844 boolean foundFullyContainedFocusable = false; 845 846 int count = focusables.size(); 847 for (int i = 0; i < count; i++) { 848 View view = focusables.get(i); 849 int viewTop = view.getTop(); 850 int viewBottom = view.getBottom(); 851 852 if (top < viewBottom && viewTop < bottom) { 853 /* 854 * the focusable is in the target area, it is a candidate for 855 * focusing 856 */ 857 858 final boolean viewIsFullyContained = (top < viewTop) && 859 (viewBottom < bottom); 860 861 if (focusCandidate == null) { 862 /* No candidate, take this one */ 863 focusCandidate = view; 864 foundFullyContainedFocusable = viewIsFullyContained; 865 } else { 866 final boolean viewIsCloserToBoundary = 867 (topFocus && viewTop < focusCandidate.getTop()) || 868 (!topFocus && viewBottom > focusCandidate 869 .getBottom()); 870 871 if (foundFullyContainedFocusable) { 872 if (viewIsFullyContained && viewIsCloserToBoundary) { 873 /* 874 * We're dealing with only fully contained views, so 875 * it has to be closer to the boundary to beat our 876 * candidate 877 */ 878 focusCandidate = view; 879 } 880 } else { 881 if (viewIsFullyContained) { 882 /* Any fully contained view beats a partially contained view */ 883 focusCandidate = view; 884 foundFullyContainedFocusable = true; 885 } else if (viewIsCloserToBoundary) { 886 /* 887 * Partially contained view beats another partially 888 * contained view if it's closer 889 */ 890 focusCandidate = view; 891 } 892 } 893 } 894 } 895 } 896 897 return focusCandidate; 898 } 899 900 /** 901 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 902 * method will scroll the view by one page up or down and give the focus 903 * to the topmost/bottommost component in the new visible area. If no 904 * component is a good candidate for focus, this scrollview reclaims the 905 * focus.</p> 906 * 907 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 908 * to go one page up or 909 * {@link android.view.View#FOCUS_DOWN} to go one page down 910 * @return true if the key event is consumed by this method, false otherwise 911 */ 912 public boolean pageScroll(int direction) { 913 boolean down = direction == View.FOCUS_DOWN; 914 int height = getHeight(); 915 916 if (down) { 917 mTempRect.top = getScrollY() + height; 918 int count = getChildCount(); 919 if (count > 0) { 920 View view = getChildAt(count - 1); 921 if (mTempRect.top + height > view.getBottom()) { 922 mTempRect.top = view.getBottom() - height; 923 } 924 } 925 } else { 926 mTempRect.top = getScrollY() - height; 927 if (mTempRect.top < 0) { 928 mTempRect.top = 0; 929 } 930 } 931 mTempRect.bottom = mTempRect.top + height; 932 933 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 934 } 935 936 /** 937 * <p>Handles scrolling in response to a "home/end" shortcut press. This 938 * method will scroll the view to the top or bottom and give the focus 939 * to the topmost/bottommost component in the new visible area. If no 940 * component is a good candidate for focus, this scrollview reclaims the 941 * focus.</p> 942 * 943 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 944 * to go the top of the view or 945 * {@link android.view.View#FOCUS_DOWN} to go the bottom 946 * @return true if the key event is consumed by this method, false otherwise 947 */ 948 public boolean fullScroll(int direction) { 949 boolean down = direction == View.FOCUS_DOWN; 950 int height = getHeight(); 951 952 mTempRect.top = 0; 953 mTempRect.bottom = height; 954 955 if (down) { 956 int count = getChildCount(); 957 if (count > 0) { 958 View view = getChildAt(count - 1); 959 mTempRect.bottom = view.getBottom() + mPaddingBottom; 960 mTempRect.top = mTempRect.bottom - height; 961 } 962 } 963 964 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 965 } 966 967 /** 968 * <p>Scrolls the view to make the area defined by <code>top</code> and 969 * <code>bottom</code> visible. This method attempts to give the focus 970 * to a component visible in this area. If no component can be focused in 971 * the new visible area, the focus is reclaimed by this ScrollView.</p> 972 * 973 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 974 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 975 * @param top the top offset of the new area to be made visible 976 * @param bottom the bottom offset of the new area to be made visible 977 * @return true if the key event is consumed by this method, false otherwise 978 */ 979 private boolean scrollAndFocus(int direction, int top, int bottom) { 980 boolean handled = true; 981 982 int height = getHeight(); 983 int containerTop = getScrollY(); 984 int containerBottom = containerTop + height; 985 boolean up = direction == View.FOCUS_UP; 986 987 View newFocused = findFocusableViewInBounds(up, top, bottom); 988 if (newFocused == null) { 989 newFocused = this; 990 } 991 992 if (top >= containerTop && bottom <= containerBottom) { 993 handled = false; 994 } else { 995 int delta = up ? (top - containerTop) : (bottom - containerBottom); 996 doScrollY(delta); 997 } 998 999 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1000 1001 return handled; 1002 } 1003 1004 /** 1005 * Handle scrolling in response to an up or down arrow click. 1006 * 1007 * @param direction The direction corresponding to the arrow key that was 1008 * pressed 1009 * @return True if we consumed the event, false otherwise 1010 */ 1011 public boolean arrowScroll(int direction) { 1012 1013 View currentFocused = findFocus(); 1014 if (currentFocused == this) currentFocused = null; 1015 1016 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1017 1018 final int maxJump = getMaxScrollAmount(); 1019 1020 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1021 nextFocused.getDrawingRect(mTempRect); 1022 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1023 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1024 doScrollY(scrollDelta); 1025 nextFocused.requestFocus(direction); 1026 } else { 1027 // no new focus 1028 int scrollDelta = maxJump; 1029 1030 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1031 scrollDelta = getScrollY(); 1032 } else if (direction == View.FOCUS_DOWN) { 1033 if (getChildCount() > 0) { 1034 int daBottom = getChildAt(0).getBottom(); 1035 int screenBottom = getScrollY() + getHeight() - mPaddingBottom; 1036 if (daBottom - screenBottom < maxJump) { 1037 scrollDelta = daBottom - screenBottom; 1038 } 1039 } 1040 } 1041 if (scrollDelta == 0) { 1042 return false; 1043 } 1044 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1045 } 1046 1047 if (currentFocused != null && currentFocused.isFocused() 1048 && isOffScreen(currentFocused)) { 1049 // previously focused item still has focus and is off screen, give 1050 // it up (take it back to ourselves) 1051 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1052 // sure to 1053 // get it) 1054 final int descendantFocusability = getDescendantFocusability(); // save 1055 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1056 requestFocus(); 1057 setDescendantFocusability(descendantFocusability); // restore 1058 } 1059 return true; 1060 } 1061 1062 /** 1063 * @return whether the descendant of this scroll view is scrolled off 1064 * screen. 1065 */ 1066 private boolean isOffScreen(View descendant) { 1067 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1068 } 1069 1070 /** 1071 * @return whether the descendant of this scroll view is within delta 1072 * pixels of being on the screen. 1073 */ 1074 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1075 descendant.getDrawingRect(mTempRect); 1076 offsetDescendantRectToMyCoords(descendant, mTempRect); 1077 1078 return (mTempRect.bottom + delta) >= getScrollY() 1079 && (mTempRect.top - delta) <= (getScrollY() + height); 1080 } 1081 1082 /** 1083 * Smooth scroll by a Y delta 1084 * 1085 * @param delta the number of pixels to scroll by on the Y axis 1086 */ 1087 private void doScrollY(int delta) { 1088 if (delta != 0) { 1089 if (mSmoothScrollingEnabled) { 1090 smoothScrollBy(0, delta); 1091 } else { 1092 scrollBy(0, delta); 1093 } 1094 } 1095 } 1096 1097 /** 1098 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1099 * 1100 * @param dx the number of pixels to scroll by on the X axis 1101 * @param dy the number of pixels to scroll by on the Y axis 1102 */ 1103 public final void smoothScrollBy(int dx, int dy) { 1104 if (getChildCount() == 0) { 1105 // Nothing to do. 1106 return; 1107 } 1108 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1109 if (duration > ANIMATED_SCROLL_GAP) { 1110 final int height = getHeight() - mPaddingBottom - mPaddingTop; 1111 final int bottom = getChildAt(0).getHeight(); 1112 final int maxY = Math.max(0, bottom - height); 1113 final int scrollY = mScrollY; 1114 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1115 1116 mScroller.startScroll(mScrollX, scrollY, 0, dy); 1117 postInvalidateOnAnimation(); 1118 } else { 1119 if (!mScroller.isFinished()) { 1120 mScroller.abortAnimation(); 1121 if (mFlingStrictSpan != null) { 1122 mFlingStrictSpan.finish(); 1123 mFlingStrictSpan = null; 1124 } 1125 } 1126 scrollBy(dx, dy); 1127 } 1128 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1129 } 1130 1131 /** 1132 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1133 * 1134 * @param x the position where to scroll on the X axis 1135 * @param y the position where to scroll on the Y axis 1136 */ 1137 public final void smoothScrollTo(int x, int y) { 1138 smoothScrollBy(x - mScrollX, y - mScrollY); 1139 } 1140 1141 /** 1142 * <p>The scroll range of a scroll view is the overall height of all of its 1143 * children.</p> 1144 */ 1145 @Override 1146 protected int computeVerticalScrollRange() { 1147 final int count = getChildCount(); 1148 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1149 if (count == 0) { 1150 return contentHeight; 1151 } 1152 1153 int scrollRange = getChildAt(0).getBottom(); 1154 final int scrollY = mScrollY; 1155 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1156 if (scrollY < 0) { 1157 scrollRange -= scrollY; 1158 } else if (scrollY > overscrollBottom) { 1159 scrollRange += scrollY - overscrollBottom; 1160 } 1161 1162 return scrollRange; 1163 } 1164 1165 @Override 1166 protected int computeVerticalScrollOffset() { 1167 return Math.max(0, super.computeVerticalScrollOffset()); 1168 } 1169 1170 @Override 1171 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1172 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1173 1174 int childWidthMeasureSpec; 1175 int childHeightMeasureSpec; 1176 1177 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1178 + mPaddingRight, lp.width); 1179 1180 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1181 1182 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1183 } 1184 1185 @Override 1186 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1187 int parentHeightMeasureSpec, int heightUsed) { 1188 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1189 1190 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1191 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1192 + widthUsed, lp.width); 1193 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1194 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1195 1196 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1197 } 1198 1199 @Override 1200 public void computeScroll() { 1201 if (mScroller.computeScrollOffset()) { 1202 // This is called at drawing time by ViewGroup. We don't want to 1203 // re-show the scrollbars at this point, which scrollTo will do, 1204 // so we replicate most of scrollTo here. 1205 // 1206 // It's a little odd to call onScrollChanged from inside the drawing. 1207 // 1208 // It is, except when you remember that computeScroll() is used to 1209 // animate scrolling. So unless we want to defer the onScrollChanged() 1210 // until the end of the animated scrolling, we don't really have a 1211 // choice here. 1212 // 1213 // I agree. The alternative, which I think would be worse, is to post 1214 // something and tell the subclasses later. This is bad because there 1215 // will be a window where mScrollX/Y is different from what the app 1216 // thinks it is. 1217 // 1218 int oldX = mScrollX; 1219 int oldY = mScrollY; 1220 int x = mScroller.getCurrX(); 1221 int y = mScroller.getCurrY(); 1222 1223 if (oldX != x || oldY != y) { 1224 final int range = getScrollRange(); 1225 final int overscrollMode = getOverScrollMode(); 1226 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1227 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1228 1229 overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, range, 1230 0, mOverflingDistance, false); 1231 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1232 1233 if (canOverscroll) { 1234 if (y < 0 && oldY >= 0) { 1235 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1236 } else if (y > range && oldY <= range) { 1237 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1238 } 1239 } 1240 } 1241 1242 if (!awakenScrollBars()) { 1243 // Keep on drawing until the animation has finished. 1244 postInvalidateOnAnimation(); 1245 } 1246 } else { 1247 if (mFlingStrictSpan != null) { 1248 mFlingStrictSpan.finish(); 1249 mFlingStrictSpan = null; 1250 } 1251 } 1252 } 1253 1254 /** 1255 * Scrolls the view to the given child. 1256 * 1257 * @param child the View to scroll to 1258 */ 1259 private void scrollToChild(View child) { 1260 child.getDrawingRect(mTempRect); 1261 1262 /* Offset from child's local coordinates to ScrollView coordinates */ 1263 offsetDescendantRectToMyCoords(child, mTempRect); 1264 1265 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1266 1267 if (scrollDelta != 0) { 1268 scrollBy(0, scrollDelta); 1269 } 1270 } 1271 1272 /** 1273 * If rect is off screen, scroll just enough to get it (or at least the 1274 * first screen size chunk of it) on screen. 1275 * 1276 * @param rect The rectangle. 1277 * @param immediate True to scroll immediately without animation 1278 * @return true if scrolling was performed 1279 */ 1280 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1281 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1282 final boolean scroll = delta != 0; 1283 if (scroll) { 1284 if (immediate) { 1285 scrollBy(0, delta); 1286 } else { 1287 smoothScrollBy(0, delta); 1288 } 1289 } 1290 return scroll; 1291 } 1292 1293 /** 1294 * Compute the amount to scroll in the Y direction in order to get 1295 * a rectangle completely on the screen (or, if taller than the screen, 1296 * at least the first screen size chunk of it). 1297 * 1298 * @param rect The rect. 1299 * @return The scroll delta. 1300 */ 1301 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1302 if (getChildCount() == 0) return 0; 1303 1304 int height = getHeight(); 1305 int screenTop = getScrollY(); 1306 int screenBottom = screenTop + height; 1307 1308 int fadingEdge = getVerticalFadingEdgeLength(); 1309 1310 // leave room for top fading edge as long as rect isn't at very top 1311 if (rect.top > 0) { 1312 screenTop += fadingEdge; 1313 } 1314 1315 // leave room for bottom fading edge as long as rect isn't at very bottom 1316 if (rect.bottom < getChildAt(0).getHeight()) { 1317 screenBottom -= fadingEdge; 1318 } 1319 1320 int scrollYDelta = 0; 1321 1322 if (rect.bottom > screenBottom && rect.top > screenTop) { 1323 // need to move down to get it in view: move down just enough so 1324 // that the entire rectangle is in view (or at least the first 1325 // screen size chunk). 1326 1327 if (rect.height() > height) { 1328 // just enough to get screen size chunk on 1329 scrollYDelta += (rect.top - screenTop); 1330 } else { 1331 // get entire rect at bottom of screen 1332 scrollYDelta += (rect.bottom - screenBottom); 1333 } 1334 1335 // make sure we aren't scrolling beyond the end of our content 1336 int bottom = getChildAt(0).getBottom(); 1337 int distanceToBottom = bottom - screenBottom; 1338 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1339 1340 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1341 // need to move up to get it in view: move up just enough so that 1342 // entire rectangle is in view (or at least the first screen 1343 // size chunk of it). 1344 1345 if (rect.height() > height) { 1346 // screen size chunk 1347 scrollYDelta -= (screenBottom - rect.bottom); 1348 } else { 1349 // entire rect at top 1350 scrollYDelta -= (screenTop - rect.top); 1351 } 1352 1353 // make sure we aren't scrolling any further than the top our content 1354 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1355 } 1356 return scrollYDelta; 1357 } 1358 1359 @Override 1360 public void requestChildFocus(View child, View focused) { 1361 if (!mIsLayoutDirty) { 1362 scrollToChild(focused); 1363 } else { 1364 // The child may not be laid out yet, we can't compute the scroll yet 1365 mChildToScrollTo = focused; 1366 } 1367 super.requestChildFocus(child, focused); 1368 } 1369 1370 1371 /** 1372 * When looking for focus in children of a scroll view, need to be a little 1373 * more careful not to give focus to something that is scrolled off screen. 1374 * 1375 * This is more expensive than the default {@link android.view.ViewGroup} 1376 * implementation, otherwise this behavior might have been made the default. 1377 */ 1378 @Override 1379 protected boolean onRequestFocusInDescendants(int direction, 1380 Rect previouslyFocusedRect) { 1381 1382 // convert from forward / backward notation to up / down / left / right 1383 // (ugh). 1384 if (direction == View.FOCUS_FORWARD) { 1385 direction = View.FOCUS_DOWN; 1386 } else if (direction == View.FOCUS_BACKWARD) { 1387 direction = View.FOCUS_UP; 1388 } 1389 1390 final View nextFocus = previouslyFocusedRect == null ? 1391 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1392 FocusFinder.getInstance().findNextFocusFromRect(this, 1393 previouslyFocusedRect, direction); 1394 1395 if (nextFocus == null) { 1396 return false; 1397 } 1398 1399 if (isOffScreen(nextFocus)) { 1400 return false; 1401 } 1402 1403 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1404 } 1405 1406 @Override 1407 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1408 boolean immediate) { 1409 // offset into coordinate space of this scroll view 1410 rectangle.offset(child.getLeft() - child.getScrollX(), 1411 child.getTop() - child.getScrollY()); 1412 1413 return scrollToChildRect(rectangle, immediate); 1414 } 1415 1416 @Override 1417 public void requestLayout() { 1418 mIsLayoutDirty = true; 1419 super.requestLayout(); 1420 } 1421 1422 @Override 1423 protected void onDetachedFromWindow() { 1424 super.onDetachedFromWindow(); 1425 1426 if (mScrollStrictSpan != null) { 1427 mScrollStrictSpan.finish(); 1428 mScrollStrictSpan = null; 1429 } 1430 if (mFlingStrictSpan != null) { 1431 mFlingStrictSpan.finish(); 1432 mFlingStrictSpan = null; 1433 } 1434 } 1435 1436 @Override 1437 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1438 super.onLayout(changed, l, t, r, b); 1439 mIsLayoutDirty = false; 1440 // Give a child focus if it needs it 1441 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1442 scrollToChild(mChildToScrollTo); 1443 } 1444 mChildToScrollTo = null; 1445 1446 // Calling this with the present values causes it to re-claim them 1447 scrollTo(mScrollX, mScrollY); 1448 } 1449 1450 @Override 1451 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1452 super.onSizeChanged(w, h, oldw, oldh); 1453 1454 View currentFocused = findFocus(); 1455 if (null == currentFocused || this == currentFocused) 1456 return; 1457 1458 // If the currently-focused view was visible on the screen when the 1459 // screen was at the old height, then scroll the screen to make that 1460 // view visible with the new screen height. 1461 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1462 currentFocused.getDrawingRect(mTempRect); 1463 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1464 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1465 doScrollY(scrollDelta); 1466 } 1467 } 1468 1469 /** 1470 * Return true if child is a descendant of parent, (or equal to the parent). 1471 */ 1472 private static boolean isViewDescendantOf(View child, View parent) { 1473 if (child == parent) { 1474 return true; 1475 } 1476 1477 final ViewParent theParent = child.getParent(); 1478 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1479 } 1480 1481 /** 1482 * Fling the scroll view 1483 * 1484 * @param velocityY The initial velocity in the Y direction. Positive 1485 * numbers mean that the finger/cursor is moving down the screen, 1486 * which means we want to scroll towards the top. 1487 */ 1488 public void fling(int velocityY) { 1489 if (getChildCount() > 0) { 1490 int height = getHeight() - mPaddingBottom - mPaddingTop; 1491 int bottom = getChildAt(0).getHeight(); 1492 1493 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1494 Math.max(0, bottom - height), 0, height/2); 1495 1496 if (mFlingStrictSpan == null) { 1497 mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling"); 1498 } 1499 1500 postInvalidateOnAnimation(); 1501 } 1502 } 1503 1504 private void endDrag() { 1505 mIsBeingDragged = false; 1506 1507 recycleVelocityTracker(); 1508 1509 if (mEdgeGlowTop != null) { 1510 mEdgeGlowTop.onRelease(); 1511 mEdgeGlowBottom.onRelease(); 1512 } 1513 1514 if (mScrollStrictSpan != null) { 1515 mScrollStrictSpan.finish(); 1516 mScrollStrictSpan = null; 1517 } 1518 } 1519 1520 /** 1521 * {@inheritDoc} 1522 * 1523 * <p>This version also clamps the scrolling to the bounds of our child. 1524 */ 1525 @Override 1526 public void scrollTo(int x, int y) { 1527 // we rely on the fact the View.scrollBy calls scrollTo. 1528 if (getChildCount() > 0) { 1529 View child = getChildAt(0); 1530 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1531 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1532 if (x != mScrollX || y != mScrollY) { 1533 super.scrollTo(x, y); 1534 } 1535 } 1536 } 1537 1538 @Override 1539 public void setOverScrollMode(int mode) { 1540 if (mode != OVER_SCROLL_NEVER) { 1541 if (mEdgeGlowTop == null) { 1542 Context context = getContext(); 1543 mEdgeGlowTop = new EdgeEffect(context); 1544 mEdgeGlowBottom = new EdgeEffect(context); 1545 } 1546 } else { 1547 mEdgeGlowTop = null; 1548 mEdgeGlowBottom = null; 1549 } 1550 super.setOverScrollMode(mode); 1551 } 1552 1553 @Override 1554 public void draw(Canvas canvas) { 1555 super.draw(canvas); 1556 if (mEdgeGlowTop != null) { 1557 final int scrollY = mScrollY; 1558 if (!mEdgeGlowTop.isFinished()) { 1559 final int restoreCount = canvas.save(); 1560 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1561 1562 canvas.translate(mPaddingLeft, Math.min(0, scrollY)); 1563 mEdgeGlowTop.setSize(width, getHeight()); 1564 if (mEdgeGlowTop.draw(canvas)) { 1565 postInvalidateOnAnimation(); 1566 } 1567 canvas.restoreToCount(restoreCount); 1568 } 1569 if (!mEdgeGlowBottom.isFinished()) { 1570 final int restoreCount = canvas.save(); 1571 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1572 final int height = getHeight(); 1573 1574 canvas.translate(-width + mPaddingLeft, 1575 Math.max(getScrollRange(), scrollY) + height); 1576 canvas.rotate(180, width, 0); 1577 mEdgeGlowBottom.setSize(width, height); 1578 if (mEdgeGlowBottom.draw(canvas)) { 1579 postInvalidateOnAnimation(); 1580 } 1581 canvas.restoreToCount(restoreCount); 1582 } 1583 } 1584 } 1585 1586 private static int clamp(int n, int my, int child) { 1587 if (my >= child || n < 0) { 1588 /* my >= child is this case: 1589 * |--------------- me ---------------| 1590 * |------ child ------| 1591 * or 1592 * |--------------- me ---------------| 1593 * |------ child ------| 1594 * or 1595 * |--------------- me ---------------| 1596 * |------ child ------| 1597 * 1598 * n < 0 is this case: 1599 * |------ me ------| 1600 * |-------- child --------| 1601 * |-- mScrollX --| 1602 */ 1603 return 0; 1604 } 1605 if ((my+n) > child) { 1606 /* this case: 1607 * |------ me ------| 1608 * |------ child ------| 1609 * |-- mScrollX --| 1610 */ 1611 return child-my; 1612 } 1613 return n; 1614 } 1615} 1616