ScrollView.java revision f76a50ce8fdc6aea22cabc77b2977a1a15a79630
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.StrictMode; 26import android.util.AttributeSet; 27import android.view.FocusFinder; 28import android.view.InputDevice; 29import android.view.KeyEvent; 30import android.view.MotionEvent; 31import android.view.VelocityTracker; 32import android.view.View; 33import android.view.ViewConfiguration; 34import android.view.ViewDebug; 35import android.view.ViewGroup; 36import android.view.ViewParent; 37import android.view.accessibility.AccessibilityEvent; 38import android.view.accessibility.AccessibilityNodeInfo; 39import android.view.animation.AnimationUtils; 40 41import java.util.List; 42 43/** 44 * Layout container for a view hierarchy that can be scrolled by the user, 45 * allowing it to be larger than the physical display. A ScrollView 46 * is a {@link FrameLayout}, meaning you should place one child in it 47 * containing the entire contents to scroll; this child may itself be a layout 48 * manager with a complex hierarchy of objects. A child that is often used 49 * is a {@link LinearLayout} in a vertical orientation, presenting a vertical 50 * array of top-level items that the user can scroll through. 51 * 52 * <p>The {@link TextView} class also 53 * takes care of its own scrolling, so does not require a ScrollView, but 54 * using the two together is possible to achieve the effect of a text view 55 * within a larger container. 56 * 57 * <p>ScrollView only supports vertical scrolling. 58 * 59 * @attr ref android.R.styleable#ScrollView_fillViewport 60 */ 61public class ScrollView extends FrameLayout { 62 static final int ANIMATED_SCROLL_GAP = 250; 63 64 static final float MAX_SCROLL_FACTOR = 0.5f; 65 66 private long mLastScroll; 67 68 private final Rect mTempRect = new Rect(); 69 private OverScroller mScroller; 70 private EdgeEffect mEdgeGlowTop; 71 private EdgeEffect mEdgeGlowBottom; 72 73 /** 74 * Position of the last motion event. 75 */ 76 private float mLastMotionY; 77 78 /** 79 * True when the layout has changed but the traversal has not come through yet. 80 * Ideally the view hierarchy would keep track of this for us. 81 */ 82 private boolean mIsLayoutDirty = true; 83 84 /** 85 * The child to give focus to in the event that a child has requested focus while the 86 * layout is dirty. This prevents the scroll from being wrong if the child has not been 87 * laid out before requesting focus. 88 */ 89 private View mChildToScrollTo = null; 90 91 /** 92 * True if the user is currently dragging this ScrollView around. This is 93 * not the same as 'is being flinged', which can be checked by 94 * mScroller.isFinished() (flinging begins when the user lifts his finger). 95 */ 96 private boolean mIsBeingDragged = false; 97 98 /** 99 * Determines speed during touch scrolling 100 */ 101 private VelocityTracker mVelocityTracker; 102 103 /** 104 * When set to true, the scroll view measure its child to make it fill the currently 105 * visible area. 106 */ 107 @ViewDebug.ExportedProperty(category = "layout") 108 private boolean mFillViewport; 109 110 /** 111 * Whether arrow scrolling is animated. 112 */ 113 private boolean mSmoothScrollingEnabled = true; 114 115 private int mTouchSlop; 116 private int mMinimumVelocity; 117 private int mMaximumVelocity; 118 119 private int mOverscrollDistance; 120 private int mOverflingDistance; 121 122 /** 123 * ID of the active pointer. This is used to retain consistency during 124 * drags/flings if multiple pointers are used. 125 */ 126 private int mActivePointerId = INVALID_POINTER; 127 128 /** 129 * The StrictMode "critical time span" objects to catch animation 130 * stutters. Non-null when a time-sensitive animation is 131 * in-flight. Must call finish() on them when done animating. 132 * These are no-ops on user builds. 133 */ 134 private StrictMode.Span mScrollStrictSpan = null; // aka "drag" 135 private StrictMode.Span mFlingStrictSpan = null; 136 137 /** 138 * Sentinel value for no current active pointer. 139 * Used by {@link #mActivePointerId}. 140 */ 141 private static final int INVALID_POINTER = -1; 142 143 public ScrollView(Context context) { 144 this(context, null); 145 } 146 147 public ScrollView(Context context, AttributeSet attrs) { 148 this(context, attrs, com.android.internal.R.attr.scrollViewStyle); 149 } 150 151 public ScrollView(Context context, AttributeSet attrs, int defStyle) { 152 super(context, attrs, defStyle); 153 initScrollView(); 154 155 TypedArray a = 156 context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ScrollView, defStyle, 0); 157 158 setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false)); 159 160 a.recycle(); 161 } 162 163 @Override 164 public boolean shouldDelayChildPressedState() { 165 return true; 166 } 167 168 @Override 169 protected float getTopFadingEdgeStrength() { 170 if (getChildCount() == 0) { 171 return 0.0f; 172 } 173 174 final int length = getVerticalFadingEdgeLength(); 175 if (mScrollY < length) { 176 return mScrollY / (float) length; 177 } 178 179 return 1.0f; 180 } 181 182 @Override 183 protected float getBottomFadingEdgeStrength() { 184 if (getChildCount() == 0) { 185 return 0.0f; 186 } 187 188 final int length = getVerticalFadingEdgeLength(); 189 final int bottomEdge = getHeight() - mPaddingBottom; 190 final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge; 191 if (span < length) { 192 return span / (float) length; 193 } 194 195 return 1.0f; 196 } 197 198 /** 199 * @return The maximum amount this scroll view will scroll in response to 200 * an arrow event. 201 */ 202 public int getMaxScrollAmount() { 203 return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop)); 204 } 205 206 207 private void initScrollView() { 208 mScroller = new OverScroller(getContext()); 209 setFocusable(true); 210 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 211 setWillNotDraw(false); 212 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 213 mTouchSlop = configuration.getScaledTouchSlop(); 214 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 215 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 216 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 217 mOverflingDistance = configuration.getScaledOverflingDistance(); 218 } 219 220 @Override 221 public void addView(View child) { 222 if (getChildCount() > 0) { 223 throw new IllegalStateException("ScrollView can host only one direct child"); 224 } 225 226 super.addView(child); 227 } 228 229 @Override 230 public void addView(View child, int index) { 231 if (getChildCount() > 0) { 232 throw new IllegalStateException("ScrollView can host only one direct child"); 233 } 234 235 super.addView(child, index); 236 } 237 238 @Override 239 public void addView(View child, ViewGroup.LayoutParams params) { 240 if (getChildCount() > 0) { 241 throw new IllegalStateException("ScrollView can host only one direct child"); 242 } 243 244 super.addView(child, params); 245 } 246 247 @Override 248 public void addView(View child, int index, ViewGroup.LayoutParams params) { 249 if (getChildCount() > 0) { 250 throw new IllegalStateException("ScrollView can host only one direct child"); 251 } 252 253 super.addView(child, index, params); 254 } 255 256 /** 257 * @return Returns true this ScrollView can be scrolled 258 */ 259 private boolean canScroll() { 260 View child = getChildAt(0); 261 if (child != null) { 262 int childHeight = child.getHeight(); 263 return getHeight() < childHeight + mPaddingTop + mPaddingBottom; 264 } 265 return false; 266 } 267 268 /** 269 * Indicates whether this ScrollView's content is stretched to fill the viewport. 270 * 271 * @return True if the content fills the viewport, false otherwise. 272 * 273 * @attr ref android.R.styleable#ScrollView_fillViewport 274 */ 275 public boolean isFillViewport() { 276 return mFillViewport; 277 } 278 279 /** 280 * Indicates this ScrollView whether it should stretch its content height to fill 281 * the viewport or not. 282 * 283 * @param fillViewport True to stretch the content's height to the viewport's 284 * boundaries, false otherwise. 285 * 286 * @attr ref android.R.styleable#ScrollView_fillViewport 287 */ 288 public void setFillViewport(boolean fillViewport) { 289 if (fillViewport != mFillViewport) { 290 mFillViewport = fillViewport; 291 requestLayout(); 292 } 293 } 294 295 /** 296 * @return Whether arrow scrolling will animate its transition. 297 */ 298 public boolean isSmoothScrollingEnabled() { 299 return mSmoothScrollingEnabled; 300 } 301 302 /** 303 * Set whether arrow scrolling will animate its transition. 304 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 305 */ 306 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 307 mSmoothScrollingEnabled = smoothScrollingEnabled; 308 } 309 310 @Override 311 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 312 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 313 314 if (!mFillViewport) { 315 return; 316 } 317 318 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 319 if (heightMode == MeasureSpec.UNSPECIFIED) { 320 return; 321 } 322 323 if (getChildCount() > 0) { 324 final View child = getChildAt(0); 325 int height = getMeasuredHeight(); 326 if (child.getMeasuredHeight() < height) { 327 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 328 329 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 330 mPaddingLeft + mPaddingRight, lp.width); 331 height -= mPaddingTop; 332 height -= mPaddingBottom; 333 int childHeightMeasureSpec = 334 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 335 336 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 337 } 338 } 339 } 340 341 @Override 342 public boolean dispatchKeyEvent(KeyEvent event) { 343 // Let the focused view and/or our descendants get the key first 344 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 345 } 346 347 /** 348 * You can call this function yourself to have the scroll view perform 349 * scrolling from a key event, just as if the event had been dispatched to 350 * it by the view hierarchy. 351 * 352 * @param event The key event to execute. 353 * @return Return true if the event was handled, else false. 354 */ 355 public boolean executeKeyEvent(KeyEvent event) { 356 mTempRect.setEmpty(); 357 358 if (!canScroll()) { 359 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 360 View currentFocused = findFocus(); 361 if (currentFocused == this) currentFocused = null; 362 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 363 currentFocused, View.FOCUS_DOWN); 364 return nextFocused != null 365 && nextFocused != this 366 && nextFocused.requestFocus(View.FOCUS_DOWN); 367 } 368 return false; 369 } 370 371 boolean handled = false; 372 if (event.getAction() == KeyEvent.ACTION_DOWN) { 373 switch (event.getKeyCode()) { 374 case KeyEvent.KEYCODE_DPAD_UP: 375 if (!event.isAltPressed()) { 376 handled = arrowScroll(View.FOCUS_UP); 377 } else { 378 handled = fullScroll(View.FOCUS_UP); 379 } 380 break; 381 case KeyEvent.KEYCODE_DPAD_DOWN: 382 if (!event.isAltPressed()) { 383 handled = arrowScroll(View.FOCUS_DOWN); 384 } else { 385 handled = fullScroll(View.FOCUS_DOWN); 386 } 387 break; 388 case KeyEvent.KEYCODE_SPACE: 389 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 390 break; 391 } 392 } 393 394 return handled; 395 } 396 397 private boolean inChild(int x, int y) { 398 if (getChildCount() > 0) { 399 final int scrollY = mScrollY; 400 final View child = getChildAt(0); 401 return !(y < child.getTop() - scrollY 402 || y >= child.getBottom() - scrollY 403 || x < child.getLeft() 404 || x >= child.getRight()); 405 } 406 return false; 407 } 408 409 private void initOrResetVelocityTracker() { 410 if (mVelocityTracker == null) { 411 mVelocityTracker = VelocityTracker.obtain(); 412 } else { 413 mVelocityTracker.clear(); 414 } 415 } 416 417 private void initVelocityTrackerIfNotExists() { 418 if (mVelocityTracker == null) { 419 mVelocityTracker = VelocityTracker.obtain(); 420 } 421 } 422 423 private void recycleVelocityTracker() { 424 if (mVelocityTracker != null) { 425 mVelocityTracker.recycle(); 426 mVelocityTracker = null; 427 } 428 } 429 430 @Override 431 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 432 if (disallowIntercept) { 433 recycleVelocityTracker(); 434 } 435 super.requestDisallowInterceptTouchEvent(disallowIntercept); 436 } 437 438 439 @Override 440 public boolean onInterceptTouchEvent(MotionEvent ev) { 441 /* 442 * This method JUST determines whether we want to intercept the motion. 443 * If we return true, onMotionEvent will be called and we do the actual 444 * scrolling there. 445 */ 446 447 /* 448 * Shortcut the most recurring case: the user is in the dragging 449 * state and he is moving his finger. We want to intercept this 450 * motion. 451 */ 452 final int action = ev.getAction(); 453 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 454 return true; 455 } 456 457 switch (action & MotionEvent.ACTION_MASK) { 458 case MotionEvent.ACTION_MOVE: { 459 /* 460 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 461 * whether the user has moved far enough from his original down touch. 462 */ 463 464 /* 465 * Locally do absolute value. mLastMotionY is set to the y value 466 * of the down event. 467 */ 468 final int activePointerId = mActivePointerId; 469 if (activePointerId == INVALID_POINTER) { 470 // If we don't have a valid id, the touch down wasn't on content. 471 break; 472 } 473 474 final int pointerIndex = ev.findPointerIndex(activePointerId); 475 final float y = ev.getY(pointerIndex); 476 final int yDiff = (int) Math.abs(y - mLastMotionY); 477 if (yDiff > mTouchSlop) { 478 mIsBeingDragged = true; 479 mLastMotionY = y; 480 initVelocityTrackerIfNotExists(); 481 mVelocityTracker.addMovement(ev); 482 if (mScrollStrictSpan == null) { 483 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 484 } 485 } 486 break; 487 } 488 489 case MotionEvent.ACTION_DOWN: { 490 final float y = ev.getY(); 491 if (!inChild((int) ev.getX(), (int) y)) { 492 mIsBeingDragged = false; 493 recycleVelocityTracker(); 494 break; 495 } 496 497 /* 498 * Remember location of down touch. 499 * ACTION_DOWN always refers to pointer index 0. 500 */ 501 mLastMotionY = y; 502 mActivePointerId = ev.getPointerId(0); 503 504 initOrResetVelocityTracker(); 505 mVelocityTracker.addMovement(ev); 506 /* 507 * If being flinged and user touches the screen, initiate drag; 508 * otherwise don't. mScroller.isFinished should be false when 509 * being flinged. 510 */ 511 mIsBeingDragged = !mScroller.isFinished(); 512 if (mIsBeingDragged && mScrollStrictSpan == null) { 513 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 514 } 515 break; 516 } 517 518 case MotionEvent.ACTION_CANCEL: 519 case MotionEvent.ACTION_UP: 520 /* Release the drag */ 521 mIsBeingDragged = false; 522 mActivePointerId = INVALID_POINTER; 523 recycleVelocityTracker(); 524 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 525 invalidate(); 526 } 527 break; 528 case MotionEvent.ACTION_POINTER_UP: 529 onSecondaryPointerUp(ev); 530 break; 531 } 532 533 /* 534 * The only time we want to intercept motion events is if we are in the 535 * drag mode. 536 */ 537 return mIsBeingDragged; 538 } 539 540 @Override 541 public boolean onTouchEvent(MotionEvent ev) { 542 initVelocityTrackerIfNotExists(); 543 mVelocityTracker.addMovement(ev); 544 545 final int action = ev.getAction(); 546 547 switch (action & MotionEvent.ACTION_MASK) { 548 case MotionEvent.ACTION_DOWN: { 549 mIsBeingDragged = getChildCount() != 0; 550 if (!mIsBeingDragged) { 551 return false; 552 } 553 554 /* 555 * If being flinged and user touches, stop the fling. isFinished 556 * will be false if being flinged. 557 */ 558 if (!mScroller.isFinished()) { 559 mScroller.abortAnimation(); 560 if (mFlingStrictSpan != null) { 561 mFlingStrictSpan.finish(); 562 mFlingStrictSpan = null; 563 } 564 } 565 566 // Remember where the motion event started 567 mLastMotionY = ev.getY(); 568 mActivePointerId = ev.getPointerId(0); 569 break; 570 } 571 case MotionEvent.ACTION_MOVE: 572 if (mIsBeingDragged) { 573 // Scroll to follow the motion event 574 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 575 final float y = ev.getY(activePointerIndex); 576 final int deltaY = (int) (mLastMotionY - y); 577 mLastMotionY = y; 578 579 final int oldX = mScrollX; 580 final int oldY = mScrollY; 581 final int range = getScrollRange(); 582 final int overscrollMode = getOverScrollMode(); 583 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 584 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 585 586 if (overScrollBy(0, deltaY, 0, mScrollY, 587 0, range, 0, mOverscrollDistance, true)) { 588 // Break our velocity if we hit a scroll barrier. 589 mVelocityTracker.clear(); 590 } 591 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 592 593 if (canOverscroll) { 594 final int pulledToY = oldY + deltaY; 595 if (pulledToY < 0) { 596 mEdgeGlowTop.onPull((float) deltaY / getHeight()); 597 if (!mEdgeGlowBottom.isFinished()) { 598 mEdgeGlowBottom.onRelease(); 599 } 600 } else if (pulledToY > range) { 601 mEdgeGlowBottom.onPull((float) deltaY / getHeight()); 602 if (!mEdgeGlowTop.isFinished()) { 603 mEdgeGlowTop.onRelease(); 604 } 605 } 606 if (mEdgeGlowTop != null 607 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 608 invalidate(); 609 } 610 } 611 } 612 break; 613 case MotionEvent.ACTION_UP: 614 if (mIsBeingDragged) { 615 final VelocityTracker velocityTracker = mVelocityTracker; 616 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 617 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 618 619 if (getChildCount() > 0) { 620 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 621 fling(-initialVelocity); 622 } else { 623 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, 624 getScrollRange())) { 625 invalidate(); 626 } 627 } 628 } 629 630 mActivePointerId = INVALID_POINTER; 631 endDrag(); 632 } 633 break; 634 case MotionEvent.ACTION_CANCEL: 635 if (mIsBeingDragged && getChildCount() > 0) { 636 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 637 invalidate(); 638 } 639 mActivePointerId = INVALID_POINTER; 640 endDrag(); 641 } 642 break; 643 case MotionEvent.ACTION_POINTER_DOWN: { 644 final int index = ev.getActionIndex(); 645 final float y = ev.getY(index); 646 mLastMotionY = y; 647 mActivePointerId = ev.getPointerId(index); 648 break; 649 } 650 case MotionEvent.ACTION_POINTER_UP: 651 onSecondaryPointerUp(ev); 652 mLastMotionY = ev.getY(ev.findPointerIndex(mActivePointerId)); 653 break; 654 } 655 return true; 656 } 657 658 private void onSecondaryPointerUp(MotionEvent ev) { 659 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 660 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 661 final int pointerId = ev.getPointerId(pointerIndex); 662 if (pointerId == mActivePointerId) { 663 // This was our active pointer going up. Choose a new 664 // active pointer and adjust accordingly. 665 // TODO: Make this decision more intelligent. 666 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 667 mLastMotionY = ev.getY(newPointerIndex); 668 mActivePointerId = ev.getPointerId(newPointerIndex); 669 if (mVelocityTracker != null) { 670 mVelocityTracker.clear(); 671 } 672 } 673 } 674 675 @Override 676 public boolean onGenericMotionEvent(MotionEvent event) { 677 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 678 switch (event.getAction()) { 679 case MotionEvent.ACTION_SCROLL: { 680 if (!mIsBeingDragged) { 681 final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); 682 if (vscroll != 0) { 683 final int delta = (int) (vscroll * getVerticalScrollFactor()); 684 final int range = getScrollRange(); 685 int oldScrollY = mScrollY; 686 int newScrollY = oldScrollY - delta; 687 if (newScrollY < 0) { 688 newScrollY = 0; 689 } else if (newScrollY > range) { 690 newScrollY = range; 691 } 692 if (newScrollY != oldScrollY) { 693 super.scrollTo(mScrollX, newScrollY); 694 return true; 695 } 696 } 697 } 698 } 699 } 700 } 701 return super.onGenericMotionEvent(event); 702 } 703 704 @Override 705 protected void onOverScrolled(int scrollX, int scrollY, 706 boolean clampedX, boolean clampedY) { 707 // Treat animating scrolls differently; see #computeScroll() for why. 708 if (!mScroller.isFinished()) { 709 mScrollX = scrollX; 710 mScrollY = scrollY; 711 invalidateParentIfNeeded(); 712 if (clampedY) { 713 mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 714 } 715 } else { 716 super.scrollTo(scrollX, scrollY); 717 } 718 awakenScrollBars(); 719 } 720 721 @Override 722 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 723 super.onInitializeAccessibilityNodeInfo(info); 724 info.setClassName(ScrollView.class.getName()); 725 info.setScrollable(getScrollRange() > 0); 726 } 727 728 @Override 729 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 730 super.onInitializeAccessibilityEvent(event); 731 event.setClassName(ScrollView.class.getName()); 732 final boolean scrollable = getScrollRange() > 0; 733 event.setScrollable(scrollable); 734 event.setScrollX(mScrollX); 735 event.setScrollY(mScrollY); 736 event.setMaxScrollX(mScrollX); 737 event.setMaxScrollY(getScrollRange()); 738 } 739 740 private int getScrollRange() { 741 int scrollRange = 0; 742 if (getChildCount() > 0) { 743 View child = getChildAt(0); 744 scrollRange = Math.max(0, 745 child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop)); 746 } 747 return scrollRange; 748 } 749 750 /** 751 * <p> 752 * Finds the next focusable component that fits in this View's bounds 753 * (excluding fading edges) pretending that this View's top is located at 754 * the parameter top. 755 * </p> 756 * 757 * @param topFocus look for a candidate at the top of the bounds if topFocus is true, 758 * or at the bottom of the bounds if topFocus is false 759 * @param top the top offset of the bounds in which a focusable must be 760 * found (the fading edge is assumed to start at this position) 761 * @param preferredFocusable the View that has highest priority and will be 762 * returned if it is within my bounds (null is valid) 763 * @return the next focusable component in the bounds or null if none can be found 764 */ 765 private View findFocusableViewInMyBounds(final boolean topFocus, 766 final int top, View preferredFocusable) { 767 /* 768 * The fading edge's transparent side should be considered for focus 769 * since it's mostly visible, so we divide the actual fading edge length 770 * by 2. 771 */ 772 final int fadingEdgeLength = getVerticalFadingEdgeLength() / 2; 773 final int topWithoutFadingEdge = top + fadingEdgeLength; 774 final int bottomWithoutFadingEdge = top + getHeight() - fadingEdgeLength; 775 776 if ((preferredFocusable != null) 777 && (preferredFocusable.getTop() < bottomWithoutFadingEdge) 778 && (preferredFocusable.getBottom() > topWithoutFadingEdge)) { 779 return preferredFocusable; 780 } 781 782 return findFocusableViewInBounds(topFocus, topWithoutFadingEdge, 783 bottomWithoutFadingEdge); 784 } 785 786 /** 787 * <p> 788 * Finds the next focusable component that fits in the specified bounds. 789 * </p> 790 * 791 * @param topFocus look for a candidate is the one at the top of the bounds 792 * if topFocus is true, or at the bottom of the bounds if topFocus is 793 * false 794 * @param top the top offset of the bounds in which a focusable must be 795 * found 796 * @param bottom the bottom offset of the bounds in which a focusable must 797 * be found 798 * @return the next focusable component in the bounds or null if none can 799 * be found 800 */ 801 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 802 803 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 804 View focusCandidate = null; 805 806 /* 807 * A fully contained focusable is one where its top is below the bound's 808 * top, and its bottom is above the bound's bottom. A partially 809 * contained focusable is one where some part of it is within the 810 * bounds, but it also has some part that is not within bounds. A fully contained 811 * focusable is preferred to a partially contained focusable. 812 */ 813 boolean foundFullyContainedFocusable = false; 814 815 int count = focusables.size(); 816 for (int i = 0; i < count; i++) { 817 View view = focusables.get(i); 818 int viewTop = view.getTop(); 819 int viewBottom = view.getBottom(); 820 821 if (top < viewBottom && viewTop < bottom) { 822 /* 823 * the focusable is in the target area, it is a candidate for 824 * focusing 825 */ 826 827 final boolean viewIsFullyContained = (top < viewTop) && 828 (viewBottom < bottom); 829 830 if (focusCandidate == null) { 831 /* No candidate, take this one */ 832 focusCandidate = view; 833 foundFullyContainedFocusable = viewIsFullyContained; 834 } else { 835 final boolean viewIsCloserToBoundary = 836 (topFocus && viewTop < focusCandidate.getTop()) || 837 (!topFocus && viewBottom > focusCandidate 838 .getBottom()); 839 840 if (foundFullyContainedFocusable) { 841 if (viewIsFullyContained && viewIsCloserToBoundary) { 842 /* 843 * We're dealing with only fully contained views, so 844 * it has to be closer to the boundary to beat our 845 * candidate 846 */ 847 focusCandidate = view; 848 } 849 } else { 850 if (viewIsFullyContained) { 851 /* Any fully contained view beats a partially contained view */ 852 focusCandidate = view; 853 foundFullyContainedFocusable = true; 854 } else if (viewIsCloserToBoundary) { 855 /* 856 * Partially contained view beats another partially 857 * contained view if it's closer 858 */ 859 focusCandidate = view; 860 } 861 } 862 } 863 } 864 } 865 866 return focusCandidate; 867 } 868 869 /** 870 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 871 * method will scroll the view by one page up or down and give the focus 872 * to the topmost/bottommost component in the new visible area. If no 873 * component is a good candidate for focus, this scrollview reclaims the 874 * focus.</p> 875 * 876 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 877 * to go one page up or 878 * {@link android.view.View#FOCUS_DOWN} to go one page down 879 * @return true if the key event is consumed by this method, false otherwise 880 */ 881 public boolean pageScroll(int direction) { 882 boolean down = direction == View.FOCUS_DOWN; 883 int height = getHeight(); 884 885 if (down) { 886 mTempRect.top = getScrollY() + height; 887 int count = getChildCount(); 888 if (count > 0) { 889 View view = getChildAt(count - 1); 890 if (mTempRect.top + height > view.getBottom()) { 891 mTempRect.top = view.getBottom() - height; 892 } 893 } 894 } else { 895 mTempRect.top = getScrollY() - height; 896 if (mTempRect.top < 0) { 897 mTempRect.top = 0; 898 } 899 } 900 mTempRect.bottom = mTempRect.top + height; 901 902 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 903 } 904 905 /** 906 * <p>Handles scrolling in response to a "home/end" shortcut press. This 907 * method will scroll the view to the top or bottom and give the focus 908 * to the topmost/bottommost component in the new visible area. If no 909 * component is a good candidate for focus, this scrollview reclaims the 910 * focus.</p> 911 * 912 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 913 * to go the top of the view or 914 * {@link android.view.View#FOCUS_DOWN} to go the bottom 915 * @return true if the key event is consumed by this method, false otherwise 916 */ 917 public boolean fullScroll(int direction) { 918 boolean down = direction == View.FOCUS_DOWN; 919 int height = getHeight(); 920 921 mTempRect.top = 0; 922 mTempRect.bottom = height; 923 924 if (down) { 925 int count = getChildCount(); 926 if (count > 0) { 927 View view = getChildAt(count - 1); 928 mTempRect.bottom = view.getBottom() + mPaddingBottom; 929 mTempRect.top = mTempRect.bottom - height; 930 } 931 } 932 933 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 934 } 935 936 /** 937 * <p>Scrolls the view to make the area defined by <code>top</code> and 938 * <code>bottom</code> visible. This method attempts to give the focus 939 * to a component visible in this area. If no component can be focused in 940 * the new visible area, the focus is reclaimed by this ScrollView.</p> 941 * 942 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 943 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 944 * @param top the top offset of the new area to be made visible 945 * @param bottom the bottom offset of the new area to be made visible 946 * @return true if the key event is consumed by this method, false otherwise 947 */ 948 private boolean scrollAndFocus(int direction, int top, int bottom) { 949 boolean handled = true; 950 951 int height = getHeight(); 952 int containerTop = getScrollY(); 953 int containerBottom = containerTop + height; 954 boolean up = direction == View.FOCUS_UP; 955 956 View newFocused = findFocusableViewInBounds(up, top, bottom); 957 if (newFocused == null) { 958 newFocused = this; 959 } 960 961 if (top >= containerTop && bottom <= containerBottom) { 962 handled = false; 963 } else { 964 int delta = up ? (top - containerTop) : (bottom - containerBottom); 965 doScrollY(delta); 966 } 967 968 if (newFocused != findFocus()) newFocused.requestFocus(direction); 969 970 return handled; 971 } 972 973 /** 974 * Handle scrolling in response to an up or down arrow click. 975 * 976 * @param direction The direction corresponding to the arrow key that was 977 * pressed 978 * @return True if we consumed the event, false otherwise 979 */ 980 public boolean arrowScroll(int direction) { 981 982 View currentFocused = findFocus(); 983 if (currentFocused == this) currentFocused = null; 984 985 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 986 987 final int maxJump = getMaxScrollAmount(); 988 989 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 990 nextFocused.getDrawingRect(mTempRect); 991 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 992 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 993 doScrollY(scrollDelta); 994 nextFocused.requestFocus(direction); 995 } else { 996 // no new focus 997 int scrollDelta = maxJump; 998 999 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1000 scrollDelta = getScrollY(); 1001 } else if (direction == View.FOCUS_DOWN) { 1002 if (getChildCount() > 0) { 1003 int daBottom = getChildAt(0).getBottom(); 1004 int screenBottom = getScrollY() + getHeight() - mPaddingBottom; 1005 if (daBottom - screenBottom < maxJump) { 1006 scrollDelta = daBottom - screenBottom; 1007 } 1008 } 1009 } 1010 if (scrollDelta == 0) { 1011 return false; 1012 } 1013 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1014 } 1015 1016 if (currentFocused != null && currentFocused.isFocused() 1017 && isOffScreen(currentFocused)) { 1018 // previously focused item still has focus and is off screen, give 1019 // it up (take it back to ourselves) 1020 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1021 // sure to 1022 // get it) 1023 final int descendantFocusability = getDescendantFocusability(); // save 1024 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1025 requestFocus(); 1026 setDescendantFocusability(descendantFocusability); // restore 1027 } 1028 return true; 1029 } 1030 1031 /** 1032 * @return whether the descendant of this scroll view is scrolled off 1033 * screen. 1034 */ 1035 private boolean isOffScreen(View descendant) { 1036 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1037 } 1038 1039 /** 1040 * @return whether the descendant of this scroll view is within delta 1041 * pixels of being on the screen. 1042 */ 1043 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1044 descendant.getDrawingRect(mTempRect); 1045 offsetDescendantRectToMyCoords(descendant, mTempRect); 1046 1047 return (mTempRect.bottom + delta) >= getScrollY() 1048 && (mTempRect.top - delta) <= (getScrollY() + height); 1049 } 1050 1051 /** 1052 * Smooth scroll by a Y delta 1053 * 1054 * @param delta the number of pixels to scroll by on the Y axis 1055 */ 1056 private void doScrollY(int delta) { 1057 if (delta != 0) { 1058 if (mSmoothScrollingEnabled) { 1059 smoothScrollBy(0, delta); 1060 } else { 1061 scrollBy(0, delta); 1062 } 1063 } 1064 } 1065 1066 /** 1067 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1068 * 1069 * @param dx the number of pixels to scroll by on the X axis 1070 * @param dy the number of pixels to scroll by on the Y axis 1071 */ 1072 public final void smoothScrollBy(int dx, int dy) { 1073 if (getChildCount() == 0) { 1074 // Nothing to do. 1075 return; 1076 } 1077 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1078 if (duration > ANIMATED_SCROLL_GAP) { 1079 final int height = getHeight() - mPaddingBottom - mPaddingTop; 1080 final int bottom = getChildAt(0).getHeight(); 1081 final int maxY = Math.max(0, bottom - height); 1082 final int scrollY = mScrollY; 1083 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1084 1085 mScroller.startScroll(mScrollX, scrollY, 0, dy); 1086 invalidate(); 1087 } else { 1088 if (!mScroller.isFinished()) { 1089 mScroller.abortAnimation(); 1090 if (mFlingStrictSpan != null) { 1091 mFlingStrictSpan.finish(); 1092 mFlingStrictSpan = null; 1093 } 1094 } 1095 scrollBy(dx, dy); 1096 } 1097 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1098 } 1099 1100 /** 1101 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1102 * 1103 * @param x the position where to scroll on the X axis 1104 * @param y the position where to scroll on the Y axis 1105 */ 1106 public final void smoothScrollTo(int x, int y) { 1107 smoothScrollBy(x - mScrollX, y - mScrollY); 1108 } 1109 1110 /** 1111 * <p>The scroll range of a scroll view is the overall height of all of its 1112 * children.</p> 1113 */ 1114 @Override 1115 protected int computeVerticalScrollRange() { 1116 final int count = getChildCount(); 1117 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1118 if (count == 0) { 1119 return contentHeight; 1120 } 1121 1122 int scrollRange = getChildAt(0).getBottom(); 1123 final int scrollY = mScrollY; 1124 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1125 if (scrollY < 0) { 1126 scrollRange -= scrollY; 1127 } else if (scrollY > overscrollBottom) { 1128 scrollRange += scrollY - overscrollBottom; 1129 } 1130 1131 return scrollRange; 1132 } 1133 1134 @Override 1135 protected int computeVerticalScrollOffset() { 1136 return Math.max(0, super.computeVerticalScrollOffset()); 1137 } 1138 1139 @Override 1140 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1141 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1142 1143 int childWidthMeasureSpec; 1144 int childHeightMeasureSpec; 1145 1146 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1147 + mPaddingRight, lp.width); 1148 1149 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1150 1151 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1152 } 1153 1154 @Override 1155 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1156 int parentHeightMeasureSpec, int heightUsed) { 1157 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1158 1159 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1160 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1161 + widthUsed, lp.width); 1162 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1163 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1164 1165 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1166 } 1167 1168 @Override 1169 public void computeScroll() { 1170 if (mScroller.computeScrollOffset()) { 1171 // This is called at drawing time by ViewGroup. We don't want to 1172 // re-show the scrollbars at this point, which scrollTo will do, 1173 // so we replicate most of scrollTo here. 1174 // 1175 // It's a little odd to call onScrollChanged from inside the drawing. 1176 // 1177 // It is, except when you remember that computeScroll() is used to 1178 // animate scrolling. So unless we want to defer the onScrollChanged() 1179 // until the end of the animated scrolling, we don't really have a 1180 // choice here. 1181 // 1182 // I agree. The alternative, which I think would be worse, is to post 1183 // something and tell the subclasses later. This is bad because there 1184 // will be a window where mScrollX/Y is different from what the app 1185 // thinks it is. 1186 // 1187 int oldX = mScrollX; 1188 int oldY = mScrollY; 1189 int x = mScroller.getCurrX(); 1190 int y = mScroller.getCurrY(); 1191 1192 if (oldX != x || oldY != y) { 1193 final int range = getScrollRange(); 1194 final int overscrollMode = getOverScrollMode(); 1195 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1196 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1197 1198 overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, range, 1199 0, mOverflingDistance, false); 1200 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1201 1202 if (canOverscroll) { 1203 if (y < 0 && oldY >= 0) { 1204 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1205 } else if (y > range && oldY <= range) { 1206 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1207 } 1208 } 1209 } 1210 1211 awakenScrollBars(); 1212 1213 // Keep on drawing until the animation has finished. 1214 postInvalidate(); 1215 } else { 1216 if (mFlingStrictSpan != null) { 1217 mFlingStrictSpan.finish(); 1218 mFlingStrictSpan = null; 1219 } 1220 } 1221 } 1222 1223 /** 1224 * Scrolls the view to the given child. 1225 * 1226 * @param child the View to scroll to 1227 */ 1228 private void scrollToChild(View child) { 1229 child.getDrawingRect(mTempRect); 1230 1231 /* Offset from child's local coordinates to ScrollView coordinates */ 1232 offsetDescendantRectToMyCoords(child, mTempRect); 1233 1234 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1235 1236 if (scrollDelta != 0) { 1237 scrollBy(0, scrollDelta); 1238 } 1239 } 1240 1241 /** 1242 * If rect is off screen, scroll just enough to get it (or at least the 1243 * first screen size chunk of it) on screen. 1244 * 1245 * @param rect The rectangle. 1246 * @param immediate True to scroll immediately without animation 1247 * @return true if scrolling was performed 1248 */ 1249 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1250 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1251 final boolean scroll = delta != 0; 1252 if (scroll) { 1253 if (immediate) { 1254 scrollBy(0, delta); 1255 } else { 1256 smoothScrollBy(0, delta); 1257 } 1258 } 1259 return scroll; 1260 } 1261 1262 /** 1263 * Compute the amount to scroll in the Y direction in order to get 1264 * a rectangle completely on the screen (or, if taller than the screen, 1265 * at least the first screen size chunk of it). 1266 * 1267 * @param rect The rect. 1268 * @return The scroll delta. 1269 */ 1270 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1271 if (getChildCount() == 0) return 0; 1272 1273 int height = getHeight(); 1274 int screenTop = getScrollY(); 1275 int screenBottom = screenTop + height; 1276 1277 int fadingEdge = getVerticalFadingEdgeLength(); 1278 1279 // leave room for top fading edge as long as rect isn't at very top 1280 if (rect.top > 0) { 1281 screenTop += fadingEdge; 1282 } 1283 1284 // leave room for bottom fading edge as long as rect isn't at very bottom 1285 if (rect.bottom < getChildAt(0).getHeight()) { 1286 screenBottom -= fadingEdge; 1287 } 1288 1289 int scrollYDelta = 0; 1290 1291 if (rect.bottom > screenBottom && rect.top > screenTop) { 1292 // need to move down to get it in view: move down just enough so 1293 // that the entire rectangle is in view (or at least the first 1294 // screen size chunk). 1295 1296 if (rect.height() > height) { 1297 // just enough to get screen size chunk on 1298 scrollYDelta += (rect.top - screenTop); 1299 } else { 1300 // get entire rect at bottom of screen 1301 scrollYDelta += (rect.bottom - screenBottom); 1302 } 1303 1304 // make sure we aren't scrolling beyond the end of our content 1305 int bottom = getChildAt(0).getBottom(); 1306 int distanceToBottom = bottom - screenBottom; 1307 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1308 1309 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1310 // need to move up to get it in view: move up just enough so that 1311 // entire rectangle is in view (or at least the first screen 1312 // size chunk of it). 1313 1314 if (rect.height() > height) { 1315 // screen size chunk 1316 scrollYDelta -= (screenBottom - rect.bottom); 1317 } else { 1318 // entire rect at top 1319 scrollYDelta -= (screenTop - rect.top); 1320 } 1321 1322 // make sure we aren't scrolling any further than the top our content 1323 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1324 } 1325 return scrollYDelta; 1326 } 1327 1328 @Override 1329 public void requestChildFocus(View child, View focused) { 1330 if (!mIsLayoutDirty) { 1331 scrollToChild(focused); 1332 } else { 1333 // The child may not be laid out yet, we can't compute the scroll yet 1334 mChildToScrollTo = focused; 1335 } 1336 super.requestChildFocus(child, focused); 1337 } 1338 1339 1340 /** 1341 * When looking for focus in children of a scroll view, need to be a little 1342 * more careful not to give focus to something that is scrolled off screen. 1343 * 1344 * This is more expensive than the default {@link android.view.ViewGroup} 1345 * implementation, otherwise this behavior might have been made the default. 1346 */ 1347 @Override 1348 protected boolean onRequestFocusInDescendants(int direction, 1349 Rect previouslyFocusedRect) { 1350 1351 // convert from forward / backward notation to up / down / left / right 1352 // (ugh). 1353 if (direction == View.FOCUS_FORWARD) { 1354 direction = View.FOCUS_DOWN; 1355 } else if (direction == View.FOCUS_BACKWARD) { 1356 direction = View.FOCUS_UP; 1357 } 1358 1359 final View nextFocus = previouslyFocusedRect == null ? 1360 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1361 FocusFinder.getInstance().findNextFocusFromRect(this, 1362 previouslyFocusedRect, direction); 1363 1364 if (nextFocus == null) { 1365 return false; 1366 } 1367 1368 if (isOffScreen(nextFocus)) { 1369 return false; 1370 } 1371 1372 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1373 } 1374 1375 @Override 1376 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1377 boolean immediate) { 1378 // offset into coordinate space of this scroll view 1379 rectangle.offset(child.getLeft() - child.getScrollX(), 1380 child.getTop() - child.getScrollY()); 1381 1382 return scrollToChildRect(rectangle, immediate); 1383 } 1384 1385 @Override 1386 public void requestLayout() { 1387 mIsLayoutDirty = true; 1388 super.requestLayout(); 1389 } 1390 1391 @Override 1392 protected void onDetachedFromWindow() { 1393 super.onDetachedFromWindow(); 1394 1395 if (mScrollStrictSpan != null) { 1396 mScrollStrictSpan.finish(); 1397 mScrollStrictSpan = null; 1398 } 1399 if (mFlingStrictSpan != null) { 1400 mFlingStrictSpan.finish(); 1401 mFlingStrictSpan = null; 1402 } 1403 } 1404 1405 @Override 1406 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1407 super.onLayout(changed, l, t, r, b); 1408 mIsLayoutDirty = false; 1409 // Give a child focus if it needs it 1410 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1411 scrollToChild(mChildToScrollTo); 1412 } 1413 mChildToScrollTo = null; 1414 1415 // Calling this with the present values causes it to re-claim them 1416 scrollTo(mScrollX, mScrollY); 1417 } 1418 1419 @Override 1420 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1421 super.onSizeChanged(w, h, oldw, oldh); 1422 1423 View currentFocused = findFocus(); 1424 if (null == currentFocused || this == currentFocused) 1425 return; 1426 1427 // If the currently-focused view was visible on the screen when the 1428 // screen was at the old height, then scroll the screen to make that 1429 // view visible with the new screen height. 1430 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1431 currentFocused.getDrawingRect(mTempRect); 1432 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1433 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1434 doScrollY(scrollDelta); 1435 } 1436 } 1437 1438 /** 1439 * Return true if child is a descendant of parent, (or equal to the parent). 1440 */ 1441 private boolean isViewDescendantOf(View child, View parent) { 1442 if (child == parent) { 1443 return true; 1444 } 1445 1446 final ViewParent theParent = child.getParent(); 1447 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1448 } 1449 1450 /** 1451 * Fling the scroll view 1452 * 1453 * @param velocityY The initial velocity in the Y direction. Positive 1454 * numbers mean that the finger/cursor is moving down the screen, 1455 * which means we want to scroll towards the top. 1456 */ 1457 public void fling(int velocityY) { 1458 if (getChildCount() > 0) { 1459 int height = getHeight() - mPaddingBottom - mPaddingTop; 1460 int bottom = getChildAt(0).getHeight(); 1461 1462 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1463 Math.max(0, bottom - height), 0, height/2); 1464 1465 final boolean movingDown = velocityY > 0; 1466 1467 if (mFlingStrictSpan == null) { 1468 mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling"); 1469 } 1470 1471 invalidate(); 1472 } 1473 } 1474 1475 private void endDrag() { 1476 mIsBeingDragged = false; 1477 1478 recycleVelocityTracker(); 1479 1480 if (mEdgeGlowTop != null) { 1481 mEdgeGlowTop.onRelease(); 1482 mEdgeGlowBottom.onRelease(); 1483 } 1484 1485 if (mScrollStrictSpan != null) { 1486 mScrollStrictSpan.finish(); 1487 mScrollStrictSpan = null; 1488 } 1489 } 1490 1491 /** 1492 * {@inheritDoc} 1493 * 1494 * <p>This version also clamps the scrolling to the bounds of our child. 1495 */ 1496 @Override 1497 public void scrollTo(int x, int y) { 1498 // we rely on the fact the View.scrollBy calls scrollTo. 1499 if (getChildCount() > 0) { 1500 View child = getChildAt(0); 1501 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1502 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1503 if (x != mScrollX || y != mScrollY) { 1504 super.scrollTo(x, y); 1505 } 1506 } 1507 } 1508 1509 @Override 1510 public void setOverScrollMode(int mode) { 1511 if (mode != OVER_SCROLL_NEVER) { 1512 if (mEdgeGlowTop == null) { 1513 Context context = getContext(); 1514 mEdgeGlowTop = new EdgeEffect(context); 1515 mEdgeGlowBottom = new EdgeEffect(context); 1516 } 1517 } else { 1518 mEdgeGlowTop = null; 1519 mEdgeGlowBottom = null; 1520 } 1521 super.setOverScrollMode(mode); 1522 } 1523 1524 @Override 1525 public void draw(Canvas canvas) { 1526 super.draw(canvas); 1527 if (mEdgeGlowTop != null) { 1528 final int scrollY = mScrollY; 1529 if (!mEdgeGlowTop.isFinished()) { 1530 final int restoreCount = canvas.save(); 1531 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1532 1533 canvas.translate(mPaddingLeft, Math.min(0, scrollY)); 1534 mEdgeGlowTop.setSize(width, getHeight()); 1535 if (mEdgeGlowTop.draw(canvas)) { 1536 invalidate(); 1537 } 1538 canvas.restoreToCount(restoreCount); 1539 } 1540 if (!mEdgeGlowBottom.isFinished()) { 1541 final int restoreCount = canvas.save(); 1542 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1543 final int height = getHeight(); 1544 1545 canvas.translate(-width + mPaddingLeft, 1546 Math.max(getScrollRange(), scrollY) + height); 1547 canvas.rotate(180, width, 0); 1548 mEdgeGlowBottom.setSize(width, height); 1549 if (mEdgeGlowBottom.draw(canvas)) { 1550 invalidate(); 1551 } 1552 canvas.restoreToCount(restoreCount); 1553 } 1554 } 1555 } 1556 1557 private int clamp(int n, int my, int child) { 1558 if (my >= child || n < 0) { 1559 /* my >= child is this case: 1560 * |--------------- me ---------------| 1561 * |------ child ------| 1562 * or 1563 * |--------------- me ---------------| 1564 * |------ child ------| 1565 * or 1566 * |--------------- me ---------------| 1567 * |------ child ------| 1568 * 1569 * n < 0 is this case: 1570 * |------ me ------| 1571 * |-------- child --------| 1572 * |-- mScrollX --| 1573 */ 1574 return 0; 1575 } 1576 if ((my+n) > child) { 1577 /* this case: 1578 * |------ me ------| 1579 * |------ child ------| 1580 * |-- mScrollX --| 1581 */ 1582 return child-my; 1583 } 1584 return n; 1585 } 1586} 1587