ScrollView.java revision 0dc291eef630cbc3c4479fff8c549567ac980f87
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.util.Log; 29import android.view.FocusFinder; 30import android.view.InputDevice; 31import android.view.KeyEvent; 32import android.view.MotionEvent; 33import android.view.VelocityTracker; 34import android.view.View; 35import android.view.ViewConfiguration; 36import android.view.ViewDebug; 37import android.view.ViewGroup; 38import android.view.ViewParent; 39import android.view.accessibility.AccessibilityEvent; 40import android.view.accessibility.AccessibilityNodeInfo; 41import android.view.animation.AnimationUtils; 42 43import java.util.List; 44 45/** 46 * Layout container for a view hierarchy that can be scrolled by the user, 47 * allowing it to be larger than the physical display. A ScrollView 48 * is a {@link FrameLayout}, meaning you should place one child in it 49 * containing the entire contents to scroll; this child may itself be a layout 50 * manager with a complex hierarchy of objects. A child that is often used 51 * is a {@link LinearLayout} in a vertical orientation, presenting a vertical 52 * array of top-level items that the user can scroll through. 53 * <p>You should never use a ScrollView with a {@link ListView}, because 54 * ListView takes care of its own vertical scrolling. Most importantly, doing this 55 * defeats all of the important optimizations in ListView for dealing with 56 * large lists, since it effectively forces the ListView to display its entire 57 * list of items to fill up the infinite container supplied by ScrollView. 58 * <p>The {@link TextView} class also 59 * takes care of its own scrolling, so does not require a ScrollView, but 60 * using the two together is possible to achieve the effect of a text view 61 * within a larger container. 62 * 63 * <p>ScrollView only supports vertical scrolling. For horizontal scrolling, 64 * use {@link HorizontalScrollView}. 65 * 66 * @attr ref android.R.styleable#ScrollView_fillViewport 67 */ 68public class ScrollView extends FrameLayout { 69 static final int ANIMATED_SCROLL_GAP = 250; 70 71 static final float MAX_SCROLL_FACTOR = 0.5f; 72 73 private static final String TAG = "ScrollView"; 74 75 private long mLastScroll; 76 77 private final Rect mTempRect = new Rect(); 78 private OverScroller mScroller; 79 private EdgeEffect mEdgeGlowTop; 80 private EdgeEffect mEdgeGlowBottom; 81 82 /** 83 * Position of the last motion event. 84 */ 85 private int mLastMotionY; 86 87 /** 88 * True when the layout has changed but the traversal has not come through yet. 89 * Ideally the view hierarchy would keep track of this for us. 90 */ 91 private boolean mIsLayoutDirty = true; 92 93 /** 94 * The child to give focus to in the event that a child has requested focus while the 95 * layout is dirty. This prevents the scroll from being wrong if the child has not been 96 * laid out before requesting focus. 97 */ 98 private View mChildToScrollTo = null; 99 100 /** 101 * True if the user is currently dragging this ScrollView around. This is 102 * not the same as 'is being flinged', which can be checked by 103 * mScroller.isFinished() (flinging begins when the user lifts his finger). 104 */ 105 private boolean mIsBeingDragged = false; 106 107 /** 108 * Determines speed during touch scrolling 109 */ 110 private VelocityTracker mVelocityTracker; 111 112 /** 113 * When set to true, the scroll view measure its child to make it fill the currently 114 * visible area. 115 */ 116 @ViewDebug.ExportedProperty(category = "layout") 117 private boolean mFillViewport; 118 119 /** 120 * Whether arrow scrolling is animated. 121 */ 122 private boolean mSmoothScrollingEnabled = true; 123 124 private int mTouchSlop; 125 private int mMinimumVelocity; 126 private int mMaximumVelocity; 127 128 private int mOverscrollDistance; 129 private int mOverflingDistance; 130 131 /** 132 * ID of the active pointer. This is used to retain consistency during 133 * drags/flings if multiple pointers are used. 134 */ 135 private int mActivePointerId = INVALID_POINTER; 136 137 /** 138 * The StrictMode "critical time span" objects to catch animation 139 * stutters. Non-null when a time-sensitive animation is 140 * in-flight. Must call finish() on them when done animating. 141 * These are no-ops on user builds. 142 */ 143 private StrictMode.Span mScrollStrictSpan = null; // aka "drag" 144 private StrictMode.Span mFlingStrictSpan = null; 145 146 /** 147 * Sentinel value for no current active pointer. 148 * Used by {@link #mActivePointerId}. 149 */ 150 private static final int INVALID_POINTER = -1; 151 152 public ScrollView(Context context) { 153 this(context, null); 154 } 155 156 public ScrollView(Context context, AttributeSet attrs) { 157 this(context, attrs, com.android.internal.R.attr.scrollViewStyle); 158 } 159 160 public ScrollView(Context context, AttributeSet attrs, int defStyle) { 161 super(context, attrs, defStyle); 162 initScrollView(); 163 164 TypedArray a = 165 context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ScrollView, defStyle, 0); 166 167 setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false)); 168 169 a.recycle(); 170 } 171 172 @Override 173 public boolean shouldDelayChildPressedState() { 174 return true; 175 } 176 177 @Override 178 protected float getTopFadingEdgeStrength() { 179 if (getChildCount() == 0) { 180 return 0.0f; 181 } 182 183 final int length = getVerticalFadingEdgeLength(); 184 if (mScrollY < length) { 185 return mScrollY / (float) length; 186 } 187 188 return 1.0f; 189 } 190 191 @Override 192 protected float getBottomFadingEdgeStrength() { 193 if (getChildCount() == 0) { 194 return 0.0f; 195 } 196 197 final int length = getVerticalFadingEdgeLength(); 198 final int bottomEdge = getHeight() - mPaddingBottom; 199 final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge; 200 if (span < length) { 201 return span / (float) length; 202 } 203 204 return 1.0f; 205 } 206 207 /** 208 * @return The maximum amount this scroll view will scroll in response to 209 * an arrow event. 210 */ 211 public int getMaxScrollAmount() { 212 return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop)); 213 } 214 215 216 private void initScrollView() { 217 mScroller = new OverScroller(getContext()); 218 setFocusable(true); 219 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 220 setWillNotDraw(false); 221 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 222 mTouchSlop = configuration.getScaledTouchSlop(); 223 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 224 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 225 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 226 mOverflingDistance = configuration.getScaledOverflingDistance(); 227 } 228 229 @Override 230 public void addView(View child) { 231 if (getChildCount() > 0) { 232 throw new IllegalStateException("ScrollView can host only one direct child"); 233 } 234 235 super.addView(child); 236 } 237 238 @Override 239 public void addView(View child, int index) { 240 if (getChildCount() > 0) { 241 throw new IllegalStateException("ScrollView can host only one direct child"); 242 } 243 244 super.addView(child, index); 245 } 246 247 @Override 248 public void addView(View child, ViewGroup.LayoutParams params) { 249 if (getChildCount() > 0) { 250 throw new IllegalStateException("ScrollView can host only one direct child"); 251 } 252 253 super.addView(child, params); 254 } 255 256 @Override 257 public void addView(View child, int index, ViewGroup.LayoutParams params) { 258 if (getChildCount() > 0) { 259 throw new IllegalStateException("ScrollView can host only one direct child"); 260 } 261 262 super.addView(child, index, params); 263 } 264 265 /** 266 * @return Returns true this ScrollView can be scrolled 267 */ 268 private boolean canScroll() { 269 View child = getChildAt(0); 270 if (child != null) { 271 int childHeight = child.getHeight(); 272 return getHeight() < childHeight + mPaddingTop + mPaddingBottom; 273 } 274 return false; 275 } 276 277 /** 278 * Indicates whether this ScrollView's content is stretched to fill the viewport. 279 * 280 * @return True if the content fills the viewport, false otherwise. 281 * 282 * @attr ref android.R.styleable#ScrollView_fillViewport 283 */ 284 public boolean isFillViewport() { 285 return mFillViewport; 286 } 287 288 /** 289 * Indicates this ScrollView whether it should stretch its content height to fill 290 * the viewport or not. 291 * 292 * @param fillViewport True to stretch the content's height to the viewport's 293 * boundaries, false otherwise. 294 * 295 * @attr ref android.R.styleable#ScrollView_fillViewport 296 */ 297 public void setFillViewport(boolean fillViewport) { 298 if (fillViewport != mFillViewport) { 299 mFillViewport = fillViewport; 300 requestLayout(); 301 } 302 } 303 304 /** 305 * @return Whether arrow scrolling will animate its transition. 306 */ 307 public boolean isSmoothScrollingEnabled() { 308 return mSmoothScrollingEnabled; 309 } 310 311 /** 312 * Set whether arrow scrolling will animate its transition. 313 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 314 */ 315 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 316 mSmoothScrollingEnabled = smoothScrollingEnabled; 317 } 318 319 @Override 320 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 321 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 322 323 if (!mFillViewport) { 324 return; 325 } 326 327 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 328 if (heightMode == MeasureSpec.UNSPECIFIED) { 329 return; 330 } 331 332 if (getChildCount() > 0) { 333 final View child = getChildAt(0); 334 int height = getMeasuredHeight(); 335 if (child.getMeasuredHeight() < height) { 336 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 337 338 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 339 mPaddingLeft + mPaddingRight, lp.width); 340 height -= mPaddingTop; 341 height -= mPaddingBottom; 342 int childHeightMeasureSpec = 343 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 344 345 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 346 } 347 } 348 } 349 350 @Override 351 public boolean dispatchKeyEvent(KeyEvent event) { 352 // Let the focused view and/or our descendants get the key first 353 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 354 } 355 356 /** 357 * You can call this function yourself to have the scroll view perform 358 * scrolling from a key event, just as if the event had been dispatched to 359 * it by the view hierarchy. 360 * 361 * @param event The key event to execute. 362 * @return Return true if the event was handled, else false. 363 */ 364 public boolean executeKeyEvent(KeyEvent event) { 365 mTempRect.setEmpty(); 366 367 if (!canScroll()) { 368 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 369 View currentFocused = findFocus(); 370 if (currentFocused == this) currentFocused = null; 371 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 372 currentFocused, View.FOCUS_DOWN); 373 return nextFocused != null 374 && nextFocused != this 375 && nextFocused.requestFocus(View.FOCUS_DOWN); 376 } 377 return false; 378 } 379 380 boolean handled = false; 381 if (event.getAction() == KeyEvent.ACTION_DOWN) { 382 switch (event.getKeyCode()) { 383 case KeyEvent.KEYCODE_DPAD_UP: 384 if (!event.isAltPressed()) { 385 handled = arrowScroll(View.FOCUS_UP); 386 } else { 387 handled = fullScroll(View.FOCUS_UP); 388 } 389 break; 390 case KeyEvent.KEYCODE_DPAD_DOWN: 391 if (!event.isAltPressed()) { 392 handled = arrowScroll(View.FOCUS_DOWN); 393 } else { 394 handled = fullScroll(View.FOCUS_DOWN); 395 } 396 break; 397 case KeyEvent.KEYCODE_SPACE: 398 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 399 break; 400 } 401 } 402 403 return handled; 404 } 405 406 private boolean inChild(int x, int y) { 407 if (getChildCount() > 0) { 408 final int scrollY = mScrollY; 409 final View child = getChildAt(0); 410 return !(y < child.getTop() - scrollY 411 || y >= child.getBottom() - scrollY 412 || x < child.getLeft() 413 || x >= child.getRight()); 414 } 415 return false; 416 } 417 418 private void initOrResetVelocityTracker() { 419 if (mVelocityTracker == null) { 420 mVelocityTracker = VelocityTracker.obtain(); 421 } else { 422 mVelocityTracker.clear(); 423 } 424 } 425 426 private void initVelocityTrackerIfNotExists() { 427 if (mVelocityTracker == null) { 428 mVelocityTracker = VelocityTracker.obtain(); 429 } 430 } 431 432 private void recycleVelocityTracker() { 433 if (mVelocityTracker != null) { 434 mVelocityTracker.recycle(); 435 mVelocityTracker = null; 436 } 437 } 438 439 @Override 440 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 441 if (disallowIntercept) { 442 recycleVelocityTracker(); 443 } 444 super.requestDisallowInterceptTouchEvent(disallowIntercept); 445 } 446 447 448 @Override 449 public boolean onInterceptTouchEvent(MotionEvent ev) { 450 /* 451 * This method JUST determines whether we want to intercept the motion. 452 * If we return true, onMotionEvent will be called and we do the actual 453 * scrolling there. 454 */ 455 456 /* 457 * Shortcut the most recurring case: the user is in the dragging 458 * state and he is moving his finger. We want to intercept this 459 * motion. 460 */ 461 final int action = ev.getAction(); 462 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 463 return true; 464 } 465 466 switch (action & MotionEvent.ACTION_MASK) { 467 case MotionEvent.ACTION_MOVE: { 468 /* 469 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 470 * whether the user has moved far enough from his original down touch. 471 */ 472 473 /* 474 * Locally do absolute value. mLastMotionY is set to the y value 475 * of the down event. 476 */ 477 final int activePointerId = mActivePointerId; 478 if (activePointerId == INVALID_POINTER) { 479 // If we don't have a valid id, the touch down wasn't on content. 480 break; 481 } 482 483 final int pointerIndex = ev.findPointerIndex(activePointerId); 484 if (pointerIndex == -1) { 485 Log.e(TAG, "Invalid pointerId=" + activePointerId 486 + " in onInterceptTouchEvent"); 487 break; 488 } 489 490 final int y = (int) ev.getY(pointerIndex); 491 final int yDiff = Math.abs(y - mLastMotionY); 492 if (yDiff > mTouchSlop) { 493 mIsBeingDragged = true; 494 mLastMotionY = y; 495 initVelocityTrackerIfNotExists(); 496 mVelocityTracker.addMovement(ev); 497 if (mScrollStrictSpan == null) { 498 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 499 } 500 final ViewParent parent = getParent(); 501 if (parent != null) { 502 parent.requestDisallowInterceptTouchEvent(true); 503 } 504 } 505 break; 506 } 507 508 case MotionEvent.ACTION_DOWN: { 509 final int y = (int) ev.getY(); 510 if (!inChild((int) ev.getX(), (int) y)) { 511 mIsBeingDragged = false; 512 recycleVelocityTracker(); 513 break; 514 } 515 516 /* 517 * Remember location of down touch. 518 * ACTION_DOWN always refers to pointer index 0. 519 */ 520 mLastMotionY = y; 521 mActivePointerId = ev.getPointerId(0); 522 523 initOrResetVelocityTracker(); 524 mVelocityTracker.addMovement(ev); 525 /* 526 * If being flinged and user touches the screen, initiate drag; 527 * otherwise don't. mScroller.isFinished should be false when 528 * being flinged. 529 */ 530 mIsBeingDragged = !mScroller.isFinished(); 531 if (mIsBeingDragged && mScrollStrictSpan == null) { 532 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 533 } 534 break; 535 } 536 537 case MotionEvent.ACTION_CANCEL: 538 case MotionEvent.ACTION_UP: 539 /* Release the drag */ 540 mIsBeingDragged = false; 541 mActivePointerId = INVALID_POINTER; 542 recycleVelocityTracker(); 543 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 544 postInvalidateOnAnimation(); 545 } 546 break; 547 case MotionEvent.ACTION_POINTER_UP: 548 onSecondaryPointerUp(ev); 549 break; 550 } 551 552 /* 553 * The only time we want to intercept motion events is if we are in the 554 * drag mode. 555 */ 556 return mIsBeingDragged; 557 } 558 559 @Override 560 public boolean onTouchEvent(MotionEvent ev) { 561 initVelocityTrackerIfNotExists(); 562 mVelocityTracker.addMovement(ev); 563 564 final int action = ev.getAction(); 565 566 switch (action & MotionEvent.ACTION_MASK) { 567 case MotionEvent.ACTION_DOWN: { 568 if (getChildCount() == 0) { 569 return false; 570 } 571 if ((mIsBeingDragged = !mScroller.isFinished())) { 572 final ViewParent parent = getParent(); 573 if (parent != null) { 574 parent.requestDisallowInterceptTouchEvent(true); 575 } 576 } 577 578 /* 579 * If being flinged and user touches, stop the fling. isFinished 580 * will be false if being flinged. 581 */ 582 if (!mScroller.isFinished()) { 583 mScroller.abortAnimation(); 584 if (mFlingStrictSpan != null) { 585 mFlingStrictSpan.finish(); 586 mFlingStrictSpan = null; 587 } 588 } 589 590 // Remember where the motion event started 591 mLastMotionY = (int) ev.getY(); 592 mActivePointerId = ev.getPointerId(0); 593 break; 594 } 595 case MotionEvent.ACTION_MOVE: 596 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 597 if (activePointerIndex == -1) { 598 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 599 break; 600 } 601 602 final int y = (int) ev.getY(activePointerIndex); 603 int deltaY = mLastMotionY - y; 604 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 605 final ViewParent parent = getParent(); 606 if (parent != null) { 607 parent.requestDisallowInterceptTouchEvent(true); 608 } 609 mIsBeingDragged = true; 610 if (deltaY > 0) { 611 deltaY -= mTouchSlop; 612 } else { 613 deltaY += mTouchSlop; 614 } 615 } 616 if (mIsBeingDragged) { 617 // Scroll to follow the motion event 618 mLastMotionY = y; 619 620 final int oldX = mScrollX; 621 final int oldY = mScrollY; 622 final int range = getScrollRange(); 623 final int overscrollMode = getOverScrollMode(); 624 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 625 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 626 627 if (overScrollBy(0, deltaY, 0, mScrollY, 628 0, range, 0, mOverscrollDistance, true)) { 629 // Break our velocity if we hit a scroll barrier. 630 mVelocityTracker.clear(); 631 } 632 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 633 634 if (canOverscroll) { 635 final int pulledToY = oldY + deltaY; 636 if (pulledToY < 0) { 637 mEdgeGlowTop.onPull((float) deltaY / getHeight()); 638 if (!mEdgeGlowBottom.isFinished()) { 639 mEdgeGlowBottom.onRelease(); 640 } 641 } else if (pulledToY > range) { 642 mEdgeGlowBottom.onPull((float) deltaY / getHeight()); 643 if (!mEdgeGlowTop.isFinished()) { 644 mEdgeGlowTop.onRelease(); 645 } 646 } 647 if (mEdgeGlowTop != null 648 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 649 postInvalidateOnAnimation(); 650 } 651 } 652 } 653 break; 654 case MotionEvent.ACTION_UP: 655 if (mIsBeingDragged) { 656 final VelocityTracker velocityTracker = mVelocityTracker; 657 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 658 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 659 660 if (getChildCount() > 0) { 661 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 662 fling(-initialVelocity); 663 } else { 664 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, 665 getScrollRange())) { 666 postInvalidateOnAnimation(); 667 } 668 } 669 } 670 671 mActivePointerId = INVALID_POINTER; 672 endDrag(); 673 } 674 break; 675 case MotionEvent.ACTION_CANCEL: 676 if (mIsBeingDragged && getChildCount() > 0) { 677 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 678 postInvalidateOnAnimation(); 679 } 680 mActivePointerId = INVALID_POINTER; 681 endDrag(); 682 } 683 break; 684 case MotionEvent.ACTION_POINTER_DOWN: { 685 final int index = ev.getActionIndex(); 686 mLastMotionY = (int) ev.getY(index); 687 mActivePointerId = ev.getPointerId(index); 688 break; 689 } 690 case MotionEvent.ACTION_POINTER_UP: 691 onSecondaryPointerUp(ev); 692 mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId)); 693 break; 694 } 695 return true; 696 } 697 698 private void onSecondaryPointerUp(MotionEvent ev) { 699 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 700 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 701 final int pointerId = ev.getPointerId(pointerIndex); 702 if (pointerId == mActivePointerId) { 703 // This was our active pointer going up. Choose a new 704 // active pointer and adjust accordingly. 705 // TODO: Make this decision more intelligent. 706 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 707 mLastMotionY = (int) ev.getY(newPointerIndex); 708 mActivePointerId = ev.getPointerId(newPointerIndex); 709 if (mVelocityTracker != null) { 710 mVelocityTracker.clear(); 711 } 712 } 713 } 714 715 @Override 716 public boolean onGenericMotionEvent(MotionEvent event) { 717 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 718 switch (event.getAction()) { 719 case MotionEvent.ACTION_SCROLL: { 720 if (!mIsBeingDragged) { 721 final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); 722 if (vscroll != 0) { 723 final int delta = (int) (vscroll * getVerticalScrollFactor()); 724 final int range = getScrollRange(); 725 int oldScrollY = mScrollY; 726 int newScrollY = oldScrollY - delta; 727 if (newScrollY < 0) { 728 newScrollY = 0; 729 } else if (newScrollY > range) { 730 newScrollY = range; 731 } 732 if (newScrollY != oldScrollY) { 733 super.scrollTo(mScrollX, newScrollY); 734 return true; 735 } 736 } 737 } 738 } 739 } 740 } 741 return super.onGenericMotionEvent(event); 742 } 743 744 @Override 745 protected void onOverScrolled(int scrollX, int scrollY, 746 boolean clampedX, boolean clampedY) { 747 // Treat animating scrolls differently; see #computeScroll() for why. 748 if (!mScroller.isFinished()) { 749 mScrollX = scrollX; 750 mScrollY = scrollY; 751 invalidateParentIfNeeded(); 752 if (clampedY) { 753 mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 754 } 755 } else { 756 super.scrollTo(scrollX, scrollY); 757 } 758 759 awakenScrollBars(); 760 } 761 762 @Override 763 public boolean performAccessibilityAction(int action, Bundle arguments) { 764 if (super.performAccessibilityAction(action, arguments)) { 765 return true; 766 } 767 if (!isEnabled()) { 768 return false; 769 } 770 switch (action) { 771 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 772 final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop; 773 final int targetScrollY = Math.min(mScrollY + viewportHeight, getScrollRange()); 774 if (targetScrollY != mScrollY) { 775 smoothScrollTo(0, targetScrollY); 776 return true; 777 } 778 } return false; 779 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 780 final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop; 781 final int targetScrollY = Math.max(mScrollY - viewportHeight, 0); 782 if (targetScrollY != mScrollY) { 783 smoothScrollTo(0, targetScrollY); 784 return true; 785 } 786 } return false; 787 } 788 return false; 789 } 790 791 @Override 792 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 793 super.onInitializeAccessibilityNodeInfo(info); 794 info.setClassName(ScrollView.class.getName()); 795 if (isEnabled()) { 796 final int scrollRange = getScrollRange(); 797 if (scrollRange > 0) { 798 info.setScrollable(true); 799 if (mScrollY > 0) { 800 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 801 } 802 if (mScrollY < scrollRange) { 803 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 804 } 805 } 806 } 807 } 808 809 @Override 810 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 811 super.onInitializeAccessibilityEvent(event); 812 event.setClassName(ScrollView.class.getName()); 813 final boolean scrollable = getScrollRange() > 0; 814 event.setScrollable(scrollable); 815 event.setScrollX(mScrollX); 816 event.setScrollY(mScrollY); 817 event.setMaxScrollX(mScrollX); 818 event.setMaxScrollY(getScrollRange()); 819 } 820 821 private int getScrollRange() { 822 int scrollRange = 0; 823 if (getChildCount() > 0) { 824 View child = getChildAt(0); 825 scrollRange = Math.max(0, 826 child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop)); 827 } 828 return scrollRange; 829 } 830 831 /** 832 * <p> 833 * Finds the next focusable component that fits in the specified bounds. 834 * </p> 835 * 836 * @param topFocus look for a candidate is the one at the top of the bounds 837 * if topFocus is true, or at the bottom of the bounds if topFocus is 838 * false 839 * @param top the top offset of the bounds in which a focusable must be 840 * found 841 * @param bottom the bottom offset of the bounds in which a focusable must 842 * be found 843 * @return the next focusable component in the bounds or null if none can 844 * be found 845 */ 846 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 847 848 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 849 View focusCandidate = null; 850 851 /* 852 * A fully contained focusable is one where its top is below the bound's 853 * top, and its bottom is above the bound's bottom. A partially 854 * contained focusable is one where some part of it is within the 855 * bounds, but it also has some part that is not within bounds. A fully contained 856 * focusable is preferred to a partially contained focusable. 857 */ 858 boolean foundFullyContainedFocusable = false; 859 860 int count = focusables.size(); 861 for (int i = 0; i < count; i++) { 862 View view = focusables.get(i); 863 int viewTop = view.getTop(); 864 int viewBottom = view.getBottom(); 865 866 if (top < viewBottom && viewTop < bottom) { 867 /* 868 * the focusable is in the target area, it is a candidate for 869 * focusing 870 */ 871 872 final boolean viewIsFullyContained = (top < viewTop) && 873 (viewBottom < bottom); 874 875 if (focusCandidate == null) { 876 /* No candidate, take this one */ 877 focusCandidate = view; 878 foundFullyContainedFocusable = viewIsFullyContained; 879 } else { 880 final boolean viewIsCloserToBoundary = 881 (topFocus && viewTop < focusCandidate.getTop()) || 882 (!topFocus && viewBottom > focusCandidate 883 .getBottom()); 884 885 if (foundFullyContainedFocusable) { 886 if (viewIsFullyContained && viewIsCloserToBoundary) { 887 /* 888 * We're dealing with only fully contained views, so 889 * it has to be closer to the boundary to beat our 890 * candidate 891 */ 892 focusCandidate = view; 893 } 894 } else { 895 if (viewIsFullyContained) { 896 /* Any fully contained view beats a partially contained view */ 897 focusCandidate = view; 898 foundFullyContainedFocusable = true; 899 } else if (viewIsCloserToBoundary) { 900 /* 901 * Partially contained view beats another partially 902 * contained view if it's closer 903 */ 904 focusCandidate = view; 905 } 906 } 907 } 908 } 909 } 910 911 return focusCandidate; 912 } 913 914 /** 915 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 916 * method will scroll the view by one page up or down and give the focus 917 * to the topmost/bottommost component in the new visible area. If no 918 * component is a good candidate for focus, this scrollview reclaims the 919 * focus.</p> 920 * 921 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 922 * to go one page up or 923 * {@link android.view.View#FOCUS_DOWN} to go one page down 924 * @return true if the key event is consumed by this method, false otherwise 925 */ 926 public boolean pageScroll(int direction) { 927 boolean down = direction == View.FOCUS_DOWN; 928 int height = getHeight(); 929 930 if (down) { 931 mTempRect.top = getScrollY() + height; 932 int count = getChildCount(); 933 if (count > 0) { 934 View view = getChildAt(count - 1); 935 if (mTempRect.top + height > view.getBottom()) { 936 mTempRect.top = view.getBottom() - height; 937 } 938 } 939 } else { 940 mTempRect.top = getScrollY() - height; 941 if (mTempRect.top < 0) { 942 mTempRect.top = 0; 943 } 944 } 945 mTempRect.bottom = mTempRect.top + height; 946 947 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 948 } 949 950 /** 951 * <p>Handles scrolling in response to a "home/end" shortcut press. This 952 * method will scroll the view to the top or bottom and give the focus 953 * to the topmost/bottommost component in the new visible area. If no 954 * component is a good candidate for focus, this scrollview reclaims the 955 * focus.</p> 956 * 957 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 958 * to go the top of the view or 959 * {@link android.view.View#FOCUS_DOWN} to go the bottom 960 * @return true if the key event is consumed by this method, false otherwise 961 */ 962 public boolean fullScroll(int direction) { 963 boolean down = direction == View.FOCUS_DOWN; 964 int height = getHeight(); 965 966 mTempRect.top = 0; 967 mTempRect.bottom = height; 968 969 if (down) { 970 int count = getChildCount(); 971 if (count > 0) { 972 View view = getChildAt(count - 1); 973 mTempRect.bottom = view.getBottom() + mPaddingBottom; 974 mTempRect.top = mTempRect.bottom - height; 975 } 976 } 977 978 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 979 } 980 981 /** 982 * <p>Scrolls the view to make the area defined by <code>top</code> and 983 * <code>bottom</code> visible. This method attempts to give the focus 984 * to a component visible in this area. If no component can be focused in 985 * the new visible area, the focus is reclaimed by this ScrollView.</p> 986 * 987 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 988 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 989 * @param top the top offset of the new area to be made visible 990 * @param bottom the bottom offset of the new area to be made visible 991 * @return true if the key event is consumed by this method, false otherwise 992 */ 993 private boolean scrollAndFocus(int direction, int top, int bottom) { 994 boolean handled = true; 995 996 int height = getHeight(); 997 int containerTop = getScrollY(); 998 int containerBottom = containerTop + height; 999 boolean up = direction == View.FOCUS_UP; 1000 1001 View newFocused = findFocusableViewInBounds(up, top, bottom); 1002 if (newFocused == null) { 1003 newFocused = this; 1004 } 1005 1006 if (top >= containerTop && bottom <= containerBottom) { 1007 handled = false; 1008 } else { 1009 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1010 doScrollY(delta); 1011 } 1012 1013 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1014 1015 return handled; 1016 } 1017 1018 /** 1019 * Handle scrolling in response to an up or down arrow click. 1020 * 1021 * @param direction The direction corresponding to the arrow key that was 1022 * pressed 1023 * @return True if we consumed the event, false otherwise 1024 */ 1025 public boolean arrowScroll(int direction) { 1026 1027 View currentFocused = findFocus(); 1028 if (currentFocused == this) currentFocused = null; 1029 1030 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1031 1032 final int maxJump = getMaxScrollAmount(); 1033 1034 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1035 nextFocused.getDrawingRect(mTempRect); 1036 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1037 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1038 doScrollY(scrollDelta); 1039 nextFocused.requestFocus(direction); 1040 } else { 1041 // no new focus 1042 int scrollDelta = maxJump; 1043 1044 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1045 scrollDelta = getScrollY(); 1046 } else if (direction == View.FOCUS_DOWN) { 1047 if (getChildCount() > 0) { 1048 int daBottom = getChildAt(0).getBottom(); 1049 int screenBottom = getScrollY() + getHeight() - mPaddingBottom; 1050 if (daBottom - screenBottom < maxJump) { 1051 scrollDelta = daBottom - screenBottom; 1052 } 1053 } 1054 } 1055 if (scrollDelta == 0) { 1056 return false; 1057 } 1058 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1059 } 1060 1061 if (currentFocused != null && currentFocused.isFocused() 1062 && isOffScreen(currentFocused)) { 1063 // previously focused item still has focus and is off screen, give 1064 // it up (take it back to ourselves) 1065 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1066 // sure to 1067 // get it) 1068 final int descendantFocusability = getDescendantFocusability(); // save 1069 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1070 requestFocus(); 1071 setDescendantFocusability(descendantFocusability); // restore 1072 } 1073 return true; 1074 } 1075 1076 /** 1077 * @return whether the descendant of this scroll view is scrolled off 1078 * screen. 1079 */ 1080 private boolean isOffScreen(View descendant) { 1081 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1082 } 1083 1084 /** 1085 * @return whether the descendant of this scroll view is within delta 1086 * pixels of being on the screen. 1087 */ 1088 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1089 descendant.getDrawingRect(mTempRect); 1090 offsetDescendantRectToMyCoords(descendant, mTempRect); 1091 1092 return (mTempRect.bottom + delta) >= getScrollY() 1093 && (mTempRect.top - delta) <= (getScrollY() + height); 1094 } 1095 1096 /** 1097 * Smooth scroll by a Y delta 1098 * 1099 * @param delta the number of pixels to scroll by on the Y axis 1100 */ 1101 private void doScrollY(int delta) { 1102 if (delta != 0) { 1103 if (mSmoothScrollingEnabled) { 1104 smoothScrollBy(0, delta); 1105 } else { 1106 scrollBy(0, delta); 1107 } 1108 } 1109 } 1110 1111 /** 1112 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1113 * 1114 * @param dx the number of pixels to scroll by on the X axis 1115 * @param dy the number of pixels to scroll by on the Y axis 1116 */ 1117 public final void smoothScrollBy(int dx, int dy) { 1118 if (getChildCount() == 0) { 1119 // Nothing to do. 1120 return; 1121 } 1122 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1123 if (duration > ANIMATED_SCROLL_GAP) { 1124 final int height = getHeight() - mPaddingBottom - mPaddingTop; 1125 final int bottom = getChildAt(0).getHeight(); 1126 final int maxY = Math.max(0, bottom - height); 1127 final int scrollY = mScrollY; 1128 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1129 1130 mScroller.startScroll(mScrollX, scrollY, 0, dy); 1131 postInvalidateOnAnimation(); 1132 } else { 1133 if (!mScroller.isFinished()) { 1134 mScroller.abortAnimation(); 1135 if (mFlingStrictSpan != null) { 1136 mFlingStrictSpan.finish(); 1137 mFlingStrictSpan = null; 1138 } 1139 } 1140 scrollBy(dx, dy); 1141 } 1142 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1143 } 1144 1145 /** 1146 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1147 * 1148 * @param x the position where to scroll on the X axis 1149 * @param y the position where to scroll on the Y axis 1150 */ 1151 public final void smoothScrollTo(int x, int y) { 1152 smoothScrollBy(x - mScrollX, y - mScrollY); 1153 } 1154 1155 /** 1156 * <p>The scroll range of a scroll view is the overall height of all of its 1157 * children.</p> 1158 */ 1159 @Override 1160 protected int computeVerticalScrollRange() { 1161 final int count = getChildCount(); 1162 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1163 if (count == 0) { 1164 return contentHeight; 1165 } 1166 1167 int scrollRange = getChildAt(0).getBottom(); 1168 final int scrollY = mScrollY; 1169 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1170 if (scrollY < 0) { 1171 scrollRange -= scrollY; 1172 } else if (scrollY > overscrollBottom) { 1173 scrollRange += scrollY - overscrollBottom; 1174 } 1175 1176 return scrollRange; 1177 } 1178 1179 @Override 1180 protected int computeVerticalScrollOffset() { 1181 return Math.max(0, super.computeVerticalScrollOffset()); 1182 } 1183 1184 @Override 1185 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1186 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1187 1188 int childWidthMeasureSpec; 1189 int childHeightMeasureSpec; 1190 1191 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1192 + mPaddingRight, lp.width); 1193 1194 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1195 1196 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1197 } 1198 1199 @Override 1200 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1201 int parentHeightMeasureSpec, int heightUsed) { 1202 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1203 1204 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1205 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1206 + widthUsed, lp.width); 1207 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1208 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1209 1210 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1211 } 1212 1213 @Override 1214 public void computeScroll() { 1215 if (mScroller.computeScrollOffset()) { 1216 // This is called at drawing time by ViewGroup. We don't want to 1217 // re-show the scrollbars at this point, which scrollTo will do, 1218 // so we replicate most of scrollTo here. 1219 // 1220 // It's a little odd to call onScrollChanged from inside the drawing. 1221 // 1222 // It is, except when you remember that computeScroll() is used to 1223 // animate scrolling. So unless we want to defer the onScrollChanged() 1224 // until the end of the animated scrolling, we don't really have a 1225 // choice here. 1226 // 1227 // I agree. The alternative, which I think would be worse, is to post 1228 // something and tell the subclasses later. This is bad because there 1229 // will be a window where mScrollX/Y is different from what the app 1230 // thinks it is. 1231 // 1232 int oldX = mScrollX; 1233 int oldY = mScrollY; 1234 int x = mScroller.getCurrX(); 1235 int y = mScroller.getCurrY(); 1236 1237 if (oldX != x || oldY != y) { 1238 final int range = getScrollRange(); 1239 final int overscrollMode = getOverScrollMode(); 1240 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1241 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1242 1243 overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, range, 1244 0, mOverflingDistance, false); 1245 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1246 1247 if (canOverscroll) { 1248 if (y < 0 && oldY >= 0) { 1249 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1250 } else if (y > range && oldY <= range) { 1251 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1252 } 1253 } 1254 } 1255 1256 if (!awakenScrollBars()) { 1257 // Keep on drawing until the animation has finished. 1258 postInvalidateOnAnimation(); 1259 } 1260 } else { 1261 if (mFlingStrictSpan != null) { 1262 mFlingStrictSpan.finish(); 1263 mFlingStrictSpan = null; 1264 } 1265 } 1266 } 1267 1268 /** 1269 * Scrolls the view to the given child. 1270 * 1271 * @param child the View to scroll to 1272 */ 1273 private void scrollToChild(View child) { 1274 child.getDrawingRect(mTempRect); 1275 1276 /* Offset from child's local coordinates to ScrollView coordinates */ 1277 offsetDescendantRectToMyCoords(child, mTempRect); 1278 1279 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1280 1281 if (scrollDelta != 0) { 1282 scrollBy(0, scrollDelta); 1283 } 1284 } 1285 1286 /** 1287 * If rect is off screen, scroll just enough to get it (or at least the 1288 * first screen size chunk of it) on screen. 1289 * 1290 * @param rect The rectangle. 1291 * @param immediate True to scroll immediately without animation 1292 * @return true if scrolling was performed 1293 */ 1294 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1295 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1296 final boolean scroll = delta != 0; 1297 if (scroll) { 1298 if (immediate) { 1299 scrollBy(0, delta); 1300 } else { 1301 smoothScrollBy(0, delta); 1302 } 1303 } 1304 return scroll; 1305 } 1306 1307 /** 1308 * Compute the amount to scroll in the Y direction in order to get 1309 * a rectangle completely on the screen (or, if taller than the screen, 1310 * at least the first screen size chunk of it). 1311 * 1312 * @param rect The rect. 1313 * @return The scroll delta. 1314 */ 1315 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1316 if (getChildCount() == 0) return 0; 1317 1318 int height = getHeight(); 1319 int screenTop = getScrollY(); 1320 int screenBottom = screenTop + height; 1321 1322 int fadingEdge = getVerticalFadingEdgeLength(); 1323 1324 // leave room for top fading edge as long as rect isn't at very top 1325 if (rect.top > 0) { 1326 screenTop += fadingEdge; 1327 } 1328 1329 // leave room for bottom fading edge as long as rect isn't at very bottom 1330 if (rect.bottom < getChildAt(0).getHeight()) { 1331 screenBottom -= fadingEdge; 1332 } 1333 1334 int scrollYDelta = 0; 1335 1336 if (rect.bottom > screenBottom && rect.top > screenTop) { 1337 // need to move down to get it in view: move down just enough so 1338 // that the entire rectangle is in view (or at least the first 1339 // screen size chunk). 1340 1341 if (rect.height() > height) { 1342 // just enough to get screen size chunk on 1343 scrollYDelta += (rect.top - screenTop); 1344 } else { 1345 // get entire rect at bottom of screen 1346 scrollYDelta += (rect.bottom - screenBottom); 1347 } 1348 1349 // make sure we aren't scrolling beyond the end of our content 1350 int bottom = getChildAt(0).getBottom(); 1351 int distanceToBottom = bottom - screenBottom; 1352 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1353 1354 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1355 // need to move up to get it in view: move up just enough so that 1356 // entire rectangle is in view (or at least the first screen 1357 // size chunk of it). 1358 1359 if (rect.height() > height) { 1360 // screen size chunk 1361 scrollYDelta -= (screenBottom - rect.bottom); 1362 } else { 1363 // entire rect at top 1364 scrollYDelta -= (screenTop - rect.top); 1365 } 1366 1367 // make sure we aren't scrolling any further than the top our content 1368 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1369 } 1370 return scrollYDelta; 1371 } 1372 1373 @Override 1374 public void requestChildFocus(View child, View focused) { 1375 if (!mIsLayoutDirty) { 1376 scrollToChild(focused); 1377 } else { 1378 // The child may not be laid out yet, we can't compute the scroll yet 1379 mChildToScrollTo = focused; 1380 } 1381 super.requestChildFocus(child, focused); 1382 } 1383 1384 1385 /** 1386 * When looking for focus in children of a scroll view, need to be a little 1387 * more careful not to give focus to something that is scrolled off screen. 1388 * 1389 * This is more expensive than the default {@link android.view.ViewGroup} 1390 * implementation, otherwise this behavior might have been made the default. 1391 */ 1392 @Override 1393 protected boolean onRequestFocusInDescendants(int direction, 1394 Rect previouslyFocusedRect) { 1395 1396 // convert from forward / backward notation to up / down / left / right 1397 // (ugh). 1398 if (direction == View.FOCUS_FORWARD) { 1399 direction = View.FOCUS_DOWN; 1400 } else if (direction == View.FOCUS_BACKWARD) { 1401 direction = View.FOCUS_UP; 1402 } 1403 1404 final View nextFocus = previouslyFocusedRect == null ? 1405 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1406 FocusFinder.getInstance().findNextFocusFromRect(this, 1407 previouslyFocusedRect, direction); 1408 1409 if (nextFocus == null) { 1410 return false; 1411 } 1412 1413 if (isOffScreen(nextFocus)) { 1414 return false; 1415 } 1416 1417 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1418 } 1419 1420 @Override 1421 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1422 boolean immediate) { 1423 // offset into coordinate space of this scroll view 1424 rectangle.offset(child.getLeft() - child.getScrollX(), 1425 child.getTop() - child.getScrollY()); 1426 1427 return scrollToChildRect(rectangle, immediate); 1428 } 1429 1430 @Override 1431 public void requestLayout() { 1432 mIsLayoutDirty = true; 1433 super.requestLayout(); 1434 } 1435 1436 @Override 1437 protected void onDetachedFromWindow() { 1438 super.onDetachedFromWindow(); 1439 1440 if (mScrollStrictSpan != null) { 1441 mScrollStrictSpan.finish(); 1442 mScrollStrictSpan = null; 1443 } 1444 if (mFlingStrictSpan != null) { 1445 mFlingStrictSpan.finish(); 1446 mFlingStrictSpan = null; 1447 } 1448 } 1449 1450 @Override 1451 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1452 super.onLayout(changed, l, t, r, b); 1453 mIsLayoutDirty = false; 1454 // Give a child focus if it needs it 1455 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1456 scrollToChild(mChildToScrollTo); 1457 } 1458 mChildToScrollTo = null; 1459 1460 // Calling this with the present values causes it to re-claim them 1461 scrollTo(mScrollX, mScrollY); 1462 } 1463 1464 @Override 1465 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1466 super.onSizeChanged(w, h, oldw, oldh); 1467 1468 View currentFocused = findFocus(); 1469 if (null == currentFocused || this == currentFocused) 1470 return; 1471 1472 // If the currently-focused view was visible on the screen when the 1473 // screen was at the old height, then scroll the screen to make that 1474 // view visible with the new screen height. 1475 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1476 currentFocused.getDrawingRect(mTempRect); 1477 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1478 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1479 doScrollY(scrollDelta); 1480 } 1481 } 1482 1483 /** 1484 * Return true if child is a descendant of parent, (or equal to the parent). 1485 */ 1486 private static boolean isViewDescendantOf(View child, View parent) { 1487 if (child == parent) { 1488 return true; 1489 } 1490 1491 final ViewParent theParent = child.getParent(); 1492 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1493 } 1494 1495 /** 1496 * Fling the scroll view 1497 * 1498 * @param velocityY The initial velocity in the Y direction. Positive 1499 * numbers mean that the finger/cursor is moving down the screen, 1500 * which means we want to scroll towards the top. 1501 */ 1502 public void fling(int velocityY) { 1503 if (getChildCount() > 0) { 1504 int height = getHeight() - mPaddingBottom - mPaddingTop; 1505 int bottom = getChildAt(0).getHeight(); 1506 1507 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1508 Math.max(0, bottom - height), 0, height/2); 1509 1510 if (mFlingStrictSpan == null) { 1511 mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling"); 1512 } 1513 1514 postInvalidateOnAnimation(); 1515 } 1516 } 1517 1518 private void endDrag() { 1519 mIsBeingDragged = false; 1520 1521 recycleVelocityTracker(); 1522 1523 if (mEdgeGlowTop != null) { 1524 mEdgeGlowTop.onRelease(); 1525 mEdgeGlowBottom.onRelease(); 1526 } 1527 1528 if (mScrollStrictSpan != null) { 1529 mScrollStrictSpan.finish(); 1530 mScrollStrictSpan = null; 1531 } 1532 } 1533 1534 /** 1535 * {@inheritDoc} 1536 * 1537 * <p>This version also clamps the scrolling to the bounds of our child. 1538 */ 1539 @Override 1540 public void scrollTo(int x, int y) { 1541 // we rely on the fact the View.scrollBy calls scrollTo. 1542 if (getChildCount() > 0) { 1543 View child = getChildAt(0); 1544 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1545 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1546 if (x != mScrollX || y != mScrollY) { 1547 super.scrollTo(x, y); 1548 } 1549 } 1550 } 1551 1552 @Override 1553 public void setOverScrollMode(int mode) { 1554 if (mode != OVER_SCROLL_NEVER) { 1555 if (mEdgeGlowTop == null) { 1556 Context context = getContext(); 1557 mEdgeGlowTop = new EdgeEffect(context); 1558 mEdgeGlowBottom = new EdgeEffect(context); 1559 } 1560 } else { 1561 mEdgeGlowTop = null; 1562 mEdgeGlowBottom = null; 1563 } 1564 super.setOverScrollMode(mode); 1565 } 1566 1567 @Override 1568 public void draw(Canvas canvas) { 1569 super.draw(canvas); 1570 if (mEdgeGlowTop != null) { 1571 final int scrollY = mScrollY; 1572 if (!mEdgeGlowTop.isFinished()) { 1573 final int restoreCount = canvas.save(); 1574 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1575 1576 canvas.translate(mPaddingLeft, Math.min(0, scrollY)); 1577 mEdgeGlowTop.setSize(width, getHeight()); 1578 if (mEdgeGlowTop.draw(canvas)) { 1579 postInvalidateOnAnimation(); 1580 } 1581 canvas.restoreToCount(restoreCount); 1582 } 1583 if (!mEdgeGlowBottom.isFinished()) { 1584 final int restoreCount = canvas.save(); 1585 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1586 final int height = getHeight(); 1587 1588 canvas.translate(-width + mPaddingLeft, 1589 Math.max(getScrollRange(), scrollY) + height); 1590 canvas.rotate(180, width, 0); 1591 mEdgeGlowBottom.setSize(width, height); 1592 if (mEdgeGlowBottom.draw(canvas)) { 1593 postInvalidateOnAnimation(); 1594 } 1595 canvas.restoreToCount(restoreCount); 1596 } 1597 } 1598 } 1599 1600 private static int clamp(int n, int my, int child) { 1601 if (my >= child || n < 0) { 1602 /* my >= child is this case: 1603 * |--------------- me ---------------| 1604 * |------ child ------| 1605 * or 1606 * |--------------- me ---------------| 1607 * |------ child ------| 1608 * or 1609 * |--------------- me ---------------| 1610 * |------ child ------| 1611 * 1612 * n < 0 is this case: 1613 * |------ me ------| 1614 * |-------- child --------| 1615 * |-- mScrollX --| 1616 */ 1617 return 0; 1618 } 1619 if ((my+n) > child) { 1620 /* this case: 1621 * |------ me ------| 1622 * |------ child ------| 1623 * |-- mScrollX --| 1624 */ 1625 return child-my; 1626 } 1627 return n; 1628 } 1629} 1630