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 17 package android.widget; 18 19 import android.os.Build; 20 import android.os.Parcel; 21 import android.os.Parcelable; 22 import com.android.internal.R; 23 24 import android.content.Context; 25 import android.content.res.TypedArray; 26 import android.graphics.Canvas; 27 import android.graphics.Rect; 28 import android.os.Bundle; 29 import android.os.StrictMode; 30 import android.util.AttributeSet; 31 import android.util.Log; 32 import android.view.FocusFinder; 33 import android.view.InputDevice; 34 import android.view.KeyEvent; 35 import android.view.MotionEvent; 36 import android.view.VelocityTracker; 37 import android.view.View; 38 import android.view.ViewConfiguration; 39 import android.view.ViewDebug; 40 import android.view.ViewGroup; 41 import android.view.ViewParent; 42 import android.view.accessibility.AccessibilityEvent; 43 import android.view.accessibility.AccessibilityNodeInfo; 44 import android.view.animation.AnimationUtils; 45 46 import java.util.List; 47 48 /** 49 * Layout container for a view hierarchy that can be scrolled by the user, 50 * allowing it to be larger than the physical display. A ScrollView 51 * is a {@link FrameLayout}, meaning you should place one child in it 52 * containing the entire contents to scroll; this child may itself be a layout 53 * manager with a complex hierarchy of objects. A child that is often used 54 * is a {@link LinearLayout} in a vertical orientation, presenting a vertical 55 * array of top-level items that the user can scroll through. 56 * <p>You should never use a ScrollView with a {@link ListView}, because 57 * ListView takes care of its own vertical scrolling. Most importantly, doing this 58 * defeats all of the important optimizations in ListView for dealing with 59 * large lists, since it effectively forces the ListView to display its entire 60 * list of items to fill up the infinite container supplied by ScrollView. 61 * <p>The {@link TextView} class also 62 * takes care of its own scrolling, so does not require a ScrollView, but 63 * using the two together is possible to achieve the effect of a text view 64 * within a larger container. 65 * 66 * <p>ScrollView only supports vertical scrolling. For horizontal scrolling, 67 * use {@link HorizontalScrollView}. 68 * 69 * @attr ref android.R.styleable#ScrollView_fillViewport 70 */ 71 public class ScrollView extends FrameLayout { 72 static final int ANIMATED_SCROLL_GAP = 250; 73 74 static final float MAX_SCROLL_FACTOR = 0.5f; 75 76 private static final String TAG = "ScrollView"; 77 78 private long mLastScroll; 79 80 private final Rect mTempRect = new Rect(); 81 private OverScroller mScroller; 82 private EdgeEffect mEdgeGlowTop; 83 private EdgeEffect mEdgeGlowBottom; 84 85 /** 86 * Position of the last motion event. 87 */ 88 private int mLastMotionY; 89 90 /** 91 * True when the layout has changed but the traversal has not come through yet. 92 * Ideally the view hierarchy would keep track of this for us. 93 */ 94 private boolean mIsLayoutDirty = true; 95 96 /** 97 * The child to give focus to in the event that a child has requested focus while the 98 * layout is dirty. This prevents the scroll from being wrong if the child has not been 99 * laid out before requesting focus. 100 */ 101 private View mChildToScrollTo = null; 102 103 /** 104 * True if the user is currently dragging this ScrollView around. This is 105 * not the same as 'is being flinged', which can be checked by 106 * mScroller.isFinished() (flinging begins when the user lifts his finger). 107 */ 108 private boolean mIsBeingDragged = false; 109 110 /** 111 * Determines speed during touch scrolling 112 */ 113 private VelocityTracker mVelocityTracker; 114 115 /** 116 * When set to true, the scroll view measure its child to make it fill the currently 117 * visible area. 118 */ 119 @ViewDebug.ExportedProperty(category = "layout") 120 private boolean mFillViewport; 121 122 /** 123 * Whether arrow scrolling is animated. 124 */ 125 private boolean mSmoothScrollingEnabled = true; 126 127 private int mTouchSlop; 128 private int mMinimumVelocity; 129 private int mMaximumVelocity; 130 131 private int mOverscrollDistance; 132 private int mOverflingDistance; 133 134 /** 135 * ID of the active pointer. This is used to retain consistency during 136 * drags/flings if multiple pointers are used. 137 */ 138 private int mActivePointerId = INVALID_POINTER; 139 140 /** 141 * Used during scrolling to retrieve the new offset within the window. 142 */ 143 private final int[] mScrollOffset = new int[2]; 144 private final int[] mScrollConsumed = new int[2]; 145 private int mNestedYOffset; 146 147 /** 148 * The StrictMode "critical time span" objects to catch animation 149 * stutters. Non-null when a time-sensitive animation is 150 * in-flight. Must call finish() on them when done animating. 151 * These are no-ops on user builds. 152 */ 153 private StrictMode.Span mScrollStrictSpan = null; // aka "drag" 154 private StrictMode.Span mFlingStrictSpan = null; 155 156 /** 157 * Sentinel value for no current active pointer. 158 * Used by {@link #mActivePointerId}. 159 */ 160 private static final int INVALID_POINTER = -1; 161 162 private SavedState mSavedState; 163 ScrollView(Context context)164 public ScrollView(Context context) { 165 this(context, null); 166 } 167 ScrollView(Context context, AttributeSet attrs)168 public ScrollView(Context context, AttributeSet attrs) { 169 this(context, attrs, com.android.internal.R.attr.scrollViewStyle); 170 } 171 ScrollView(Context context, AttributeSet attrs, int defStyleAttr)172 public ScrollView(Context context, AttributeSet attrs, int defStyleAttr) { 173 this(context, attrs, defStyleAttr, 0); 174 } 175 ScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)176 public ScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { 177 super(context, attrs, defStyleAttr, defStyleRes); 178 initScrollView(); 179 180 final TypedArray a = context.obtainStyledAttributes( 181 attrs, com.android.internal.R.styleable.ScrollView, defStyleAttr, defStyleRes); 182 183 setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false)); 184 185 a.recycle(); 186 } 187 188 @Override shouldDelayChildPressedState()189 public boolean shouldDelayChildPressedState() { 190 return true; 191 } 192 193 @Override getTopFadingEdgeStrength()194 protected float getTopFadingEdgeStrength() { 195 if (getChildCount() == 0) { 196 return 0.0f; 197 } 198 199 final int length = getVerticalFadingEdgeLength(); 200 if (mScrollY < length) { 201 return mScrollY / (float) length; 202 } 203 204 return 1.0f; 205 } 206 207 @Override getBottomFadingEdgeStrength()208 protected float getBottomFadingEdgeStrength() { 209 if (getChildCount() == 0) { 210 return 0.0f; 211 } 212 213 final int length = getVerticalFadingEdgeLength(); 214 final int bottomEdge = getHeight() - mPaddingBottom; 215 final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge; 216 if (span < length) { 217 return span / (float) length; 218 } 219 220 return 1.0f; 221 } 222 223 /** 224 * @return The maximum amount this scroll view will scroll in response to 225 * an arrow event. 226 */ getMaxScrollAmount()227 public int getMaxScrollAmount() { 228 return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop)); 229 } 230 231 initScrollView()232 private void initScrollView() { 233 mScroller = new OverScroller(getContext()); 234 setFocusable(true); 235 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 236 setWillNotDraw(false); 237 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 238 mTouchSlop = configuration.getScaledTouchSlop(); 239 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 240 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 241 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 242 mOverflingDistance = configuration.getScaledOverflingDistance(); 243 } 244 245 @Override addView(View child)246 public void addView(View child) { 247 if (getChildCount() > 0) { 248 throw new IllegalStateException("ScrollView can host only one direct child"); 249 } 250 251 super.addView(child); 252 } 253 254 @Override addView(View child, int index)255 public void addView(View child, int index) { 256 if (getChildCount() > 0) { 257 throw new IllegalStateException("ScrollView can host only one direct child"); 258 } 259 260 super.addView(child, index); 261 } 262 263 @Override addView(View child, ViewGroup.LayoutParams params)264 public void addView(View child, ViewGroup.LayoutParams params) { 265 if (getChildCount() > 0) { 266 throw new IllegalStateException("ScrollView can host only one direct child"); 267 } 268 269 super.addView(child, params); 270 } 271 272 @Override addView(View child, int index, ViewGroup.LayoutParams params)273 public void addView(View child, int index, ViewGroup.LayoutParams params) { 274 if (getChildCount() > 0) { 275 throw new IllegalStateException("ScrollView can host only one direct child"); 276 } 277 278 super.addView(child, index, params); 279 } 280 281 /** 282 * @return Returns true this ScrollView can be scrolled 283 */ canScroll()284 private boolean canScroll() { 285 View child = getChildAt(0); 286 if (child != null) { 287 int childHeight = child.getHeight(); 288 return getHeight() < childHeight + mPaddingTop + mPaddingBottom; 289 } 290 return false; 291 } 292 293 /** 294 * Indicates whether this ScrollView's content is stretched to fill the viewport. 295 * 296 * @return True if the content fills the viewport, false otherwise. 297 * 298 * @attr ref android.R.styleable#ScrollView_fillViewport 299 */ isFillViewport()300 public boolean isFillViewport() { 301 return mFillViewport; 302 } 303 304 /** 305 * Indicates this ScrollView whether it should stretch its content height to fill 306 * the viewport or not. 307 * 308 * @param fillViewport True to stretch the content's height to the viewport's 309 * boundaries, false otherwise. 310 * 311 * @attr ref android.R.styleable#ScrollView_fillViewport 312 */ setFillViewport(boolean fillViewport)313 public void setFillViewport(boolean fillViewport) { 314 if (fillViewport != mFillViewport) { 315 mFillViewport = fillViewport; 316 requestLayout(); 317 } 318 } 319 320 /** 321 * @return Whether arrow scrolling will animate its transition. 322 */ isSmoothScrollingEnabled()323 public boolean isSmoothScrollingEnabled() { 324 return mSmoothScrollingEnabled; 325 } 326 327 /** 328 * Set whether arrow scrolling will animate its transition. 329 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 330 */ setSmoothScrollingEnabled(boolean smoothScrollingEnabled)331 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 332 mSmoothScrollingEnabled = smoothScrollingEnabled; 333 } 334 335 @Override onMeasure(int widthMeasureSpec, int heightMeasureSpec)336 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 337 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 338 339 if (!mFillViewport) { 340 return; 341 } 342 343 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 344 if (heightMode == MeasureSpec.UNSPECIFIED) { 345 return; 346 } 347 348 if (getChildCount() > 0) { 349 final View child = getChildAt(0); 350 int height = getMeasuredHeight(); 351 if (child.getMeasuredHeight() < height) { 352 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 353 354 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 355 mPaddingLeft + mPaddingRight, lp.width); 356 height -= mPaddingTop; 357 height -= mPaddingBottom; 358 int childHeightMeasureSpec = 359 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 360 361 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 362 } 363 } 364 } 365 366 @Override dispatchKeyEvent(KeyEvent event)367 public boolean dispatchKeyEvent(KeyEvent event) { 368 // Let the focused view and/or our descendants get the key first 369 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 370 } 371 372 /** 373 * You can call this function yourself to have the scroll view perform 374 * scrolling from a key event, just as if the event had been dispatched to 375 * it by the view hierarchy. 376 * 377 * @param event The key event to execute. 378 * @return Return true if the event was handled, else false. 379 */ executeKeyEvent(KeyEvent event)380 public boolean executeKeyEvent(KeyEvent event) { 381 mTempRect.setEmpty(); 382 383 if (!canScroll()) { 384 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 385 View currentFocused = findFocus(); 386 if (currentFocused == this) currentFocused = null; 387 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 388 currentFocused, View.FOCUS_DOWN); 389 return nextFocused != null 390 && nextFocused != this 391 && nextFocused.requestFocus(View.FOCUS_DOWN); 392 } 393 return false; 394 } 395 396 boolean handled = false; 397 if (event.getAction() == KeyEvent.ACTION_DOWN) { 398 switch (event.getKeyCode()) { 399 case KeyEvent.KEYCODE_DPAD_UP: 400 if (!event.isAltPressed()) { 401 handled = arrowScroll(View.FOCUS_UP); 402 } else { 403 handled = fullScroll(View.FOCUS_UP); 404 } 405 break; 406 case KeyEvent.KEYCODE_DPAD_DOWN: 407 if (!event.isAltPressed()) { 408 handled = arrowScroll(View.FOCUS_DOWN); 409 } else { 410 handled = fullScroll(View.FOCUS_DOWN); 411 } 412 break; 413 case KeyEvent.KEYCODE_SPACE: 414 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 415 break; 416 } 417 } 418 419 return handled; 420 } 421 inChild(int x, int y)422 private boolean inChild(int x, int y) { 423 if (getChildCount() > 0) { 424 final int scrollY = mScrollY; 425 final View child = getChildAt(0); 426 return !(y < child.getTop() - scrollY 427 || y >= child.getBottom() - scrollY 428 || x < child.getLeft() 429 || x >= child.getRight()); 430 } 431 return false; 432 } 433 initOrResetVelocityTracker()434 private void initOrResetVelocityTracker() { 435 if (mVelocityTracker == null) { 436 mVelocityTracker = VelocityTracker.obtain(); 437 } else { 438 mVelocityTracker.clear(); 439 } 440 } 441 initVelocityTrackerIfNotExists()442 private void initVelocityTrackerIfNotExists() { 443 if (mVelocityTracker == null) { 444 mVelocityTracker = VelocityTracker.obtain(); 445 } 446 } 447 recycleVelocityTracker()448 private void recycleVelocityTracker() { 449 if (mVelocityTracker != null) { 450 mVelocityTracker.recycle(); 451 mVelocityTracker = null; 452 } 453 } 454 455 @Override requestDisallowInterceptTouchEvent(boolean disallowIntercept)456 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 457 if (disallowIntercept) { 458 recycleVelocityTracker(); 459 } 460 super.requestDisallowInterceptTouchEvent(disallowIntercept); 461 } 462 463 464 @Override onInterceptTouchEvent(MotionEvent ev)465 public boolean onInterceptTouchEvent(MotionEvent ev) { 466 /* 467 * This method JUST determines whether we want to intercept the motion. 468 * If we return true, onMotionEvent will be called and we do the actual 469 * scrolling there. 470 */ 471 472 /* 473 * Shortcut the most recurring case: the user is in the dragging 474 * state and he is moving his finger. We want to intercept this 475 * motion. 476 */ 477 final int action = ev.getAction(); 478 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 479 return true; 480 } 481 482 /* 483 * Don't try to intercept touch if we can't scroll anyway. 484 */ 485 if (getScrollY() == 0 && !canScrollVertically(1)) { 486 return false; 487 } 488 489 switch (action & MotionEvent.ACTION_MASK) { 490 case MotionEvent.ACTION_MOVE: { 491 /* 492 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 493 * whether the user has moved far enough from his original down touch. 494 */ 495 496 /* 497 * Locally do absolute value. mLastMotionY is set to the y value 498 * of the down event. 499 */ 500 final int activePointerId = mActivePointerId; 501 if (activePointerId == INVALID_POINTER) { 502 // If we don't have a valid id, the touch down wasn't on content. 503 break; 504 } 505 506 final int pointerIndex = ev.findPointerIndex(activePointerId); 507 if (pointerIndex == -1) { 508 Log.e(TAG, "Invalid pointerId=" + activePointerId 509 + " in onInterceptTouchEvent"); 510 break; 511 } 512 513 final int y = (int) ev.getY(pointerIndex); 514 final int yDiff = Math.abs(y - mLastMotionY); 515 if (yDiff > mTouchSlop && (getNestedScrollAxes() & SCROLL_AXIS_VERTICAL) == 0) { 516 mIsBeingDragged = true; 517 mLastMotionY = y; 518 initVelocityTrackerIfNotExists(); 519 mVelocityTracker.addMovement(ev); 520 mNestedYOffset = 0; 521 if (mScrollStrictSpan == null) { 522 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 523 } 524 final ViewParent parent = getParent(); 525 if (parent != null) { 526 parent.requestDisallowInterceptTouchEvent(true); 527 } 528 } 529 break; 530 } 531 532 case MotionEvent.ACTION_DOWN: { 533 final int y = (int) ev.getY(); 534 if (!inChild((int) ev.getX(), (int) y)) { 535 mIsBeingDragged = false; 536 recycleVelocityTracker(); 537 break; 538 } 539 540 /* 541 * Remember location of down touch. 542 * ACTION_DOWN always refers to pointer index 0. 543 */ 544 mLastMotionY = y; 545 mActivePointerId = ev.getPointerId(0); 546 547 initOrResetVelocityTracker(); 548 mVelocityTracker.addMovement(ev); 549 /* 550 * If being flinged and user touches the screen, initiate drag; 551 * otherwise don't. mScroller.isFinished should be false when 552 * being flinged. 553 */ 554 mIsBeingDragged = !mScroller.isFinished(); 555 if (mIsBeingDragged && mScrollStrictSpan == null) { 556 mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); 557 } 558 startNestedScroll(SCROLL_AXIS_VERTICAL); 559 break; 560 } 561 562 case MotionEvent.ACTION_CANCEL: 563 case MotionEvent.ACTION_UP: 564 /* Release the drag */ 565 mIsBeingDragged = false; 566 mActivePointerId = INVALID_POINTER; 567 recycleVelocityTracker(); 568 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 569 postInvalidateOnAnimation(); 570 } 571 stopNestedScroll(); 572 break; 573 case MotionEvent.ACTION_POINTER_UP: 574 onSecondaryPointerUp(ev); 575 break; 576 } 577 578 /* 579 * The only time we want to intercept motion events is if we are in the 580 * drag mode. 581 */ 582 return mIsBeingDragged; 583 } 584 585 @Override onTouchEvent(MotionEvent ev)586 public boolean onTouchEvent(MotionEvent ev) { 587 initVelocityTrackerIfNotExists(); 588 589 MotionEvent vtev = MotionEvent.obtain(ev); 590 591 final int actionMasked = ev.getActionMasked(); 592 593 if (actionMasked == MotionEvent.ACTION_DOWN) { 594 mNestedYOffset = 0; 595 } 596 vtev.offsetLocation(0, mNestedYOffset); 597 598 switch (actionMasked) { 599 case MotionEvent.ACTION_DOWN: { 600 if (getChildCount() == 0) { 601 return false; 602 } 603 if ((mIsBeingDragged = !mScroller.isFinished())) { 604 final ViewParent parent = getParent(); 605 if (parent != null) { 606 parent.requestDisallowInterceptTouchEvent(true); 607 } 608 } 609 610 /* 611 * If being flinged and user touches, stop the fling. isFinished 612 * will be false if being flinged. 613 */ 614 if (!mScroller.isFinished()) { 615 mScroller.abortAnimation(); 616 if (mFlingStrictSpan != null) { 617 mFlingStrictSpan.finish(); 618 mFlingStrictSpan = null; 619 } 620 } 621 622 // Remember where the motion event started 623 mLastMotionY = (int) ev.getY(); 624 mActivePointerId = ev.getPointerId(0); 625 startNestedScroll(SCROLL_AXIS_VERTICAL); 626 break; 627 } 628 case MotionEvent.ACTION_MOVE: 629 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 630 if (activePointerIndex == -1) { 631 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 632 break; 633 } 634 635 final int y = (int) ev.getY(activePointerIndex); 636 int deltaY = mLastMotionY - y; 637 if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) { 638 deltaY -= mScrollConsumed[1]; 639 vtev.offsetLocation(0, mScrollOffset[1]); 640 mNestedYOffset += mScrollOffset[1]; 641 } 642 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 643 final ViewParent parent = getParent(); 644 if (parent != null) { 645 parent.requestDisallowInterceptTouchEvent(true); 646 } 647 mIsBeingDragged = true; 648 if (deltaY > 0) { 649 deltaY -= mTouchSlop; 650 } else { 651 deltaY += mTouchSlop; 652 } 653 } 654 if (mIsBeingDragged) { 655 // Scroll to follow the motion event 656 mLastMotionY = y - mScrollOffset[1]; 657 658 final int oldY = mScrollY; 659 final int range = getScrollRange(); 660 final int overscrollMode = getOverScrollMode(); 661 boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 662 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 663 664 // Calling overScrollBy will call onOverScrolled, which 665 // calls onScrollChanged if applicable. 666 if (overScrollBy(0, deltaY, 0, mScrollY, 0, range, 0, mOverscrollDistance, true) 667 && !hasNestedScrollingParent()) { 668 // Break our velocity if we hit a scroll barrier. 669 mVelocityTracker.clear(); 670 } 671 672 final int scrolledDeltaY = mScrollY - oldY; 673 final int unconsumedY = deltaY - scrolledDeltaY; 674 if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) { 675 mLastMotionY -= mScrollOffset[1]; 676 vtev.offsetLocation(0, mScrollOffset[1]); 677 mNestedYOffset += mScrollOffset[1]; 678 } else if (canOverscroll) { 679 final int pulledToY = oldY + deltaY; 680 if (pulledToY < 0) { 681 mEdgeGlowTop.onPull((float) deltaY / getHeight(), 682 ev.getX(activePointerIndex) / getWidth()); 683 if (!mEdgeGlowBottom.isFinished()) { 684 mEdgeGlowBottom.onRelease(); 685 } 686 } else if (pulledToY > range) { 687 mEdgeGlowBottom.onPull((float) deltaY / getHeight(), 688 1.f - ev.getX(activePointerIndex) / getWidth()); 689 if (!mEdgeGlowTop.isFinished()) { 690 mEdgeGlowTop.onRelease(); 691 } 692 } 693 if (mEdgeGlowTop != null 694 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 695 postInvalidateOnAnimation(); 696 } 697 } 698 } 699 break; 700 case MotionEvent.ACTION_UP: 701 if (mIsBeingDragged) { 702 final VelocityTracker velocityTracker = mVelocityTracker; 703 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 704 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 705 706 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 707 flingWithNestedDispatch(-initialVelocity); 708 } else if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, 709 getScrollRange())) { 710 postInvalidateOnAnimation(); 711 } 712 713 mActivePointerId = INVALID_POINTER; 714 endDrag(); 715 } 716 break; 717 case MotionEvent.ACTION_CANCEL: 718 if (mIsBeingDragged && getChildCount() > 0) { 719 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 720 postInvalidateOnAnimation(); 721 } 722 mActivePointerId = INVALID_POINTER; 723 endDrag(); 724 } 725 break; 726 case MotionEvent.ACTION_POINTER_DOWN: { 727 final int index = ev.getActionIndex(); 728 mLastMotionY = (int) ev.getY(index); 729 mActivePointerId = ev.getPointerId(index); 730 break; 731 } 732 case MotionEvent.ACTION_POINTER_UP: 733 onSecondaryPointerUp(ev); 734 mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId)); 735 break; 736 } 737 738 if (mVelocityTracker != null) { 739 mVelocityTracker.addMovement(vtev); 740 } 741 vtev.recycle(); 742 return true; 743 } 744 onSecondaryPointerUp(MotionEvent ev)745 private void onSecondaryPointerUp(MotionEvent ev) { 746 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 747 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 748 final int pointerId = ev.getPointerId(pointerIndex); 749 if (pointerId == mActivePointerId) { 750 // This was our active pointer going up. Choose a new 751 // active pointer and adjust accordingly. 752 // TODO: Make this decision more intelligent. 753 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 754 mLastMotionY = (int) ev.getY(newPointerIndex); 755 mActivePointerId = ev.getPointerId(newPointerIndex); 756 if (mVelocityTracker != null) { 757 mVelocityTracker.clear(); 758 } 759 } 760 } 761 762 @Override onGenericMotionEvent(MotionEvent event)763 public boolean onGenericMotionEvent(MotionEvent event) { 764 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 765 switch (event.getAction()) { 766 case MotionEvent.ACTION_SCROLL: { 767 if (!mIsBeingDragged) { 768 final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); 769 if (vscroll != 0) { 770 final int delta = (int) (vscroll * getVerticalScrollFactor()); 771 final int range = getScrollRange(); 772 int oldScrollY = mScrollY; 773 int newScrollY = oldScrollY - delta; 774 if (newScrollY < 0) { 775 newScrollY = 0; 776 } else if (newScrollY > range) { 777 newScrollY = range; 778 } 779 if (newScrollY != oldScrollY) { 780 super.scrollTo(mScrollX, newScrollY); 781 return true; 782 } 783 } 784 } 785 } 786 } 787 } 788 return super.onGenericMotionEvent(event); 789 } 790 791 @Override onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY)792 protected void onOverScrolled(int scrollX, int scrollY, 793 boolean clampedX, boolean clampedY) { 794 // Treat animating scrolls differently; see #computeScroll() for why. 795 if (!mScroller.isFinished()) { 796 final int oldX = mScrollX; 797 final int oldY = mScrollY; 798 mScrollX = scrollX; 799 mScrollY = scrollY; 800 invalidateParentIfNeeded(); 801 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 802 if (clampedY) { 803 mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 804 } 805 } else { 806 super.scrollTo(scrollX, scrollY); 807 } 808 809 awakenScrollBars(); 810 } 811 812 @Override performAccessibilityAction(int action, Bundle arguments)813 public boolean performAccessibilityAction(int action, Bundle arguments) { 814 if (super.performAccessibilityAction(action, arguments)) { 815 return true; 816 } 817 if (!isEnabled()) { 818 return false; 819 } 820 switch (action) { 821 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 822 final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop; 823 final int targetScrollY = Math.min(mScrollY + viewportHeight, getScrollRange()); 824 if (targetScrollY != mScrollY) { 825 smoothScrollTo(0, targetScrollY); 826 return true; 827 } 828 } return false; 829 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 830 final int viewportHeight = getHeight() - mPaddingBottom - mPaddingTop; 831 final int targetScrollY = Math.max(mScrollY - viewportHeight, 0); 832 if (targetScrollY != mScrollY) { 833 smoothScrollTo(0, targetScrollY); 834 return true; 835 } 836 } return false; 837 } 838 return false; 839 } 840 841 @Override onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info)842 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 843 super.onInitializeAccessibilityNodeInfo(info); 844 info.setClassName(ScrollView.class.getName()); 845 if (isEnabled()) { 846 final int scrollRange = getScrollRange(); 847 if (scrollRange > 0) { 848 info.setScrollable(true); 849 if (mScrollY > 0) { 850 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 851 } 852 if (mScrollY < scrollRange) { 853 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 854 } 855 } 856 } 857 } 858 859 @Override onInitializeAccessibilityEvent(AccessibilityEvent event)860 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 861 super.onInitializeAccessibilityEvent(event); 862 event.setClassName(ScrollView.class.getName()); 863 final boolean scrollable = getScrollRange() > 0; 864 event.setScrollable(scrollable); 865 event.setScrollX(mScrollX); 866 event.setScrollY(mScrollY); 867 event.setMaxScrollX(mScrollX); 868 event.setMaxScrollY(getScrollRange()); 869 } 870 getScrollRange()871 private int getScrollRange() { 872 int scrollRange = 0; 873 if (getChildCount() > 0) { 874 View child = getChildAt(0); 875 scrollRange = Math.max(0, 876 child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop)); 877 } 878 return scrollRange; 879 } 880 881 /** 882 * <p> 883 * Finds the next focusable component that fits in the specified bounds. 884 * </p> 885 * 886 * @param topFocus look for a candidate is the one at the top of the bounds 887 * if topFocus is true, or at the bottom of the bounds if topFocus is 888 * false 889 * @param top the top offset of the bounds in which a focusable must be 890 * found 891 * @param bottom the bottom offset of the bounds in which a focusable must 892 * be found 893 * @return the next focusable component in the bounds or null if none can 894 * be found 895 */ findFocusableViewInBounds(boolean topFocus, int top, int bottom)896 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 897 898 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 899 View focusCandidate = null; 900 901 /* 902 * A fully contained focusable is one where its top is below the bound's 903 * top, and its bottom is above the bound's bottom. A partially 904 * contained focusable is one where some part of it is within the 905 * bounds, but it also has some part that is not within bounds. A fully contained 906 * focusable is preferred to a partially contained focusable. 907 */ 908 boolean foundFullyContainedFocusable = false; 909 910 int count = focusables.size(); 911 for (int i = 0; i < count; i++) { 912 View view = focusables.get(i); 913 int viewTop = view.getTop(); 914 int viewBottom = view.getBottom(); 915 916 if (top < viewBottom && viewTop < bottom) { 917 /* 918 * the focusable is in the target area, it is a candidate for 919 * focusing 920 */ 921 922 final boolean viewIsFullyContained = (top < viewTop) && 923 (viewBottom < bottom); 924 925 if (focusCandidate == null) { 926 /* No candidate, take this one */ 927 focusCandidate = view; 928 foundFullyContainedFocusable = viewIsFullyContained; 929 } else { 930 final boolean viewIsCloserToBoundary = 931 (topFocus && viewTop < focusCandidate.getTop()) || 932 (!topFocus && viewBottom > focusCandidate 933 .getBottom()); 934 935 if (foundFullyContainedFocusable) { 936 if (viewIsFullyContained && viewIsCloserToBoundary) { 937 /* 938 * We're dealing with only fully contained views, so 939 * it has to be closer to the boundary to beat our 940 * candidate 941 */ 942 focusCandidate = view; 943 } 944 } else { 945 if (viewIsFullyContained) { 946 /* Any fully contained view beats a partially contained view */ 947 focusCandidate = view; 948 foundFullyContainedFocusable = true; 949 } else if (viewIsCloserToBoundary) { 950 /* 951 * Partially contained view beats another partially 952 * contained view if it's closer 953 */ 954 focusCandidate = view; 955 } 956 } 957 } 958 } 959 } 960 961 return focusCandidate; 962 } 963 964 /** 965 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 966 * method will scroll the view by one page up or down and give the focus 967 * to the topmost/bottommost component in the new visible area. If no 968 * component is a good candidate for focus, this scrollview reclaims the 969 * focus.</p> 970 * 971 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 972 * to go one page up or 973 * {@link android.view.View#FOCUS_DOWN} to go one page down 974 * @return true if the key event is consumed by this method, false otherwise 975 */ pageScroll(int direction)976 public boolean pageScroll(int direction) { 977 boolean down = direction == View.FOCUS_DOWN; 978 int height = getHeight(); 979 980 if (down) { 981 mTempRect.top = getScrollY() + height; 982 int count = getChildCount(); 983 if (count > 0) { 984 View view = getChildAt(count - 1); 985 if (mTempRect.top + height > view.getBottom()) { 986 mTempRect.top = view.getBottom() - height; 987 } 988 } 989 } else { 990 mTempRect.top = getScrollY() - height; 991 if (mTempRect.top < 0) { 992 mTempRect.top = 0; 993 } 994 } 995 mTempRect.bottom = mTempRect.top + height; 996 997 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 998 } 999 1000 /** 1001 * <p>Handles scrolling in response to a "home/end" shortcut press. This 1002 * method will scroll the view to the top or bottom and give the focus 1003 * to the topmost/bottommost component in the new visible area. If no 1004 * component is a good candidate for focus, this scrollview reclaims the 1005 * focus.</p> 1006 * 1007 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1008 * to go the top of the view or 1009 * {@link android.view.View#FOCUS_DOWN} to go the bottom 1010 * @return true if the key event is consumed by this method, false otherwise 1011 */ fullScroll(int direction)1012 public boolean fullScroll(int direction) { 1013 boolean down = direction == View.FOCUS_DOWN; 1014 int height = getHeight(); 1015 1016 mTempRect.top = 0; 1017 mTempRect.bottom = height; 1018 1019 if (down) { 1020 int count = getChildCount(); 1021 if (count > 0) { 1022 View view = getChildAt(count - 1); 1023 mTempRect.bottom = view.getBottom() + mPaddingBottom; 1024 mTempRect.top = mTempRect.bottom - height; 1025 } 1026 } 1027 1028 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1029 } 1030 1031 /** 1032 * <p>Scrolls the view to make the area defined by <code>top</code> and 1033 * <code>bottom</code> visible. This method attempts to give the focus 1034 * to a component visible in this area. If no component can be focused in 1035 * the new visible area, the focus is reclaimed by this ScrollView.</p> 1036 * 1037 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1038 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 1039 * @param top the top offset of the new area to be made visible 1040 * @param bottom the bottom offset of the new area to be made visible 1041 * @return true if the key event is consumed by this method, false otherwise 1042 */ scrollAndFocus(int direction, int top, int bottom)1043 private boolean scrollAndFocus(int direction, int top, int bottom) { 1044 boolean handled = true; 1045 1046 int height = getHeight(); 1047 int containerTop = getScrollY(); 1048 int containerBottom = containerTop + height; 1049 boolean up = direction == View.FOCUS_UP; 1050 1051 View newFocused = findFocusableViewInBounds(up, top, bottom); 1052 if (newFocused == null) { 1053 newFocused = this; 1054 } 1055 1056 if (top >= containerTop && bottom <= containerBottom) { 1057 handled = false; 1058 } else { 1059 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1060 doScrollY(delta); 1061 } 1062 1063 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1064 1065 return handled; 1066 } 1067 1068 /** 1069 * Handle scrolling in response to an up or down arrow click. 1070 * 1071 * @param direction The direction corresponding to the arrow key that was 1072 * pressed 1073 * @return True if we consumed the event, false otherwise 1074 */ arrowScroll(int direction)1075 public boolean arrowScroll(int direction) { 1076 1077 View currentFocused = findFocus(); 1078 if (currentFocused == this) currentFocused = null; 1079 1080 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1081 1082 final int maxJump = getMaxScrollAmount(); 1083 1084 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1085 nextFocused.getDrawingRect(mTempRect); 1086 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1087 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1088 doScrollY(scrollDelta); 1089 nextFocused.requestFocus(direction); 1090 } else { 1091 // no new focus 1092 int scrollDelta = maxJump; 1093 1094 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1095 scrollDelta = getScrollY(); 1096 } else if (direction == View.FOCUS_DOWN) { 1097 if (getChildCount() > 0) { 1098 int daBottom = getChildAt(0).getBottom(); 1099 int screenBottom = getScrollY() + getHeight() - mPaddingBottom; 1100 if (daBottom - screenBottom < maxJump) { 1101 scrollDelta = daBottom - screenBottom; 1102 } 1103 } 1104 } 1105 if (scrollDelta == 0) { 1106 return false; 1107 } 1108 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1109 } 1110 1111 if (currentFocused != null && currentFocused.isFocused() 1112 && isOffScreen(currentFocused)) { 1113 // previously focused item still has focus and is off screen, give 1114 // it up (take it back to ourselves) 1115 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1116 // sure to 1117 // get it) 1118 final int descendantFocusability = getDescendantFocusability(); // save 1119 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1120 requestFocus(); 1121 setDescendantFocusability(descendantFocusability); // restore 1122 } 1123 return true; 1124 } 1125 1126 /** 1127 * @return whether the descendant of this scroll view is scrolled off 1128 * screen. 1129 */ isOffScreen(View descendant)1130 private boolean isOffScreen(View descendant) { 1131 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1132 } 1133 1134 /** 1135 * @return whether the descendant of this scroll view is within delta 1136 * pixels of being on the screen. 1137 */ isWithinDeltaOfScreen(View descendant, int delta, int height)1138 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1139 descendant.getDrawingRect(mTempRect); 1140 offsetDescendantRectToMyCoords(descendant, mTempRect); 1141 1142 return (mTempRect.bottom + delta) >= getScrollY() 1143 && (mTempRect.top - delta) <= (getScrollY() + height); 1144 } 1145 1146 /** 1147 * Smooth scroll by a Y delta 1148 * 1149 * @param delta the number of pixels to scroll by on the Y axis 1150 */ doScrollY(int delta)1151 private void doScrollY(int delta) { 1152 if (delta != 0) { 1153 if (mSmoothScrollingEnabled) { 1154 smoothScrollBy(0, delta); 1155 } else { 1156 scrollBy(0, delta); 1157 } 1158 } 1159 } 1160 1161 /** 1162 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1163 * 1164 * @param dx the number of pixels to scroll by on the X axis 1165 * @param dy the number of pixels to scroll by on the Y axis 1166 */ smoothScrollBy(int dx, int dy)1167 public final void smoothScrollBy(int dx, int dy) { 1168 if (getChildCount() == 0) { 1169 // Nothing to do. 1170 return; 1171 } 1172 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1173 if (duration > ANIMATED_SCROLL_GAP) { 1174 final int height = getHeight() - mPaddingBottom - mPaddingTop; 1175 final int bottom = getChildAt(0).getHeight(); 1176 final int maxY = Math.max(0, bottom - height); 1177 final int scrollY = mScrollY; 1178 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1179 1180 mScroller.startScroll(mScrollX, scrollY, 0, dy); 1181 postInvalidateOnAnimation(); 1182 } else { 1183 if (!mScroller.isFinished()) { 1184 mScroller.abortAnimation(); 1185 if (mFlingStrictSpan != null) { 1186 mFlingStrictSpan.finish(); 1187 mFlingStrictSpan = null; 1188 } 1189 } 1190 scrollBy(dx, dy); 1191 } 1192 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1193 } 1194 1195 /** 1196 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1197 * 1198 * @param x the position where to scroll on the X axis 1199 * @param y the position where to scroll on the Y axis 1200 */ smoothScrollTo(int x, int y)1201 public final void smoothScrollTo(int x, int y) { 1202 smoothScrollBy(x - mScrollX, y - mScrollY); 1203 } 1204 1205 /** 1206 * <p>The scroll range of a scroll view is the overall height of all of its 1207 * children.</p> 1208 */ 1209 @Override computeVerticalScrollRange()1210 protected int computeVerticalScrollRange() { 1211 final int count = getChildCount(); 1212 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1213 if (count == 0) { 1214 return contentHeight; 1215 } 1216 1217 int scrollRange = getChildAt(0).getBottom(); 1218 final int scrollY = mScrollY; 1219 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1220 if (scrollY < 0) { 1221 scrollRange -= scrollY; 1222 } else if (scrollY > overscrollBottom) { 1223 scrollRange += scrollY - overscrollBottom; 1224 } 1225 1226 return scrollRange; 1227 } 1228 1229 @Override computeVerticalScrollOffset()1230 protected int computeVerticalScrollOffset() { 1231 return Math.max(0, super.computeVerticalScrollOffset()); 1232 } 1233 1234 @Override measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec)1235 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1236 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1237 1238 int childWidthMeasureSpec; 1239 int childHeightMeasureSpec; 1240 1241 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1242 + mPaddingRight, lp.width); 1243 1244 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1245 1246 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1247 } 1248 1249 @Override measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed)1250 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1251 int parentHeightMeasureSpec, int heightUsed) { 1252 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1253 1254 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1255 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1256 + widthUsed, lp.width); 1257 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1258 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1259 1260 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1261 } 1262 1263 @Override computeScroll()1264 public void computeScroll() { 1265 if (mScroller.computeScrollOffset()) { 1266 // This is called at drawing time by ViewGroup. We don't want to 1267 // re-show the scrollbars at this point, which scrollTo will do, 1268 // so we replicate most of scrollTo here. 1269 // 1270 // It's a little odd to call onScrollChanged from inside the drawing. 1271 // 1272 // It is, except when you remember that computeScroll() is used to 1273 // animate scrolling. So unless we want to defer the onScrollChanged() 1274 // until the end of the animated scrolling, we don't really have a 1275 // choice here. 1276 // 1277 // I agree. The alternative, which I think would be worse, is to post 1278 // something and tell the subclasses later. This is bad because there 1279 // will be a window where mScrollX/Y is different from what the app 1280 // thinks it is. 1281 // 1282 int oldX = mScrollX; 1283 int oldY = mScrollY; 1284 int x = mScroller.getCurrX(); 1285 int y = mScroller.getCurrY(); 1286 1287 if (oldX != x || oldY != y) { 1288 final int range = getScrollRange(); 1289 final int overscrollMode = getOverScrollMode(); 1290 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1291 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1292 1293 overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, range, 1294 0, mOverflingDistance, false); 1295 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1296 1297 if (canOverscroll) { 1298 if (y < 0 && oldY >= 0) { 1299 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1300 } else if (y > range && oldY <= range) { 1301 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1302 } 1303 } 1304 } 1305 1306 if (!awakenScrollBars()) { 1307 // Keep on drawing until the animation has finished. 1308 postInvalidateOnAnimation(); 1309 } 1310 } else { 1311 if (mFlingStrictSpan != null) { 1312 mFlingStrictSpan.finish(); 1313 mFlingStrictSpan = null; 1314 } 1315 } 1316 } 1317 1318 /** 1319 * Scrolls the view to the given child. 1320 * 1321 * @param child the View to scroll to 1322 */ scrollToChild(View child)1323 private void scrollToChild(View child) { 1324 child.getDrawingRect(mTempRect); 1325 1326 /* Offset from child's local coordinates to ScrollView coordinates */ 1327 offsetDescendantRectToMyCoords(child, mTempRect); 1328 1329 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1330 1331 if (scrollDelta != 0) { 1332 scrollBy(0, scrollDelta); 1333 } 1334 } 1335 1336 /** 1337 * If rect is off screen, scroll just enough to get it (or at least the 1338 * first screen size chunk of it) on screen. 1339 * 1340 * @param rect The rectangle. 1341 * @param immediate True to scroll immediately without animation 1342 * @return true if scrolling was performed 1343 */ scrollToChildRect(Rect rect, boolean immediate)1344 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1345 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1346 final boolean scroll = delta != 0; 1347 if (scroll) { 1348 if (immediate) { 1349 scrollBy(0, delta); 1350 } else { 1351 smoothScrollBy(0, delta); 1352 } 1353 } 1354 return scroll; 1355 } 1356 1357 /** 1358 * Compute the amount to scroll in the Y direction in order to get 1359 * a rectangle completely on the screen (or, if taller than the screen, 1360 * at least the first screen size chunk of it). 1361 * 1362 * @param rect The rect. 1363 * @return The scroll delta. 1364 */ computeScrollDeltaToGetChildRectOnScreen(Rect rect)1365 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1366 if (getChildCount() == 0) return 0; 1367 1368 int height = getHeight(); 1369 int screenTop = getScrollY(); 1370 int screenBottom = screenTop + height; 1371 1372 int fadingEdge = getVerticalFadingEdgeLength(); 1373 1374 // leave room for top fading edge as long as rect isn't at very top 1375 if (rect.top > 0) { 1376 screenTop += fadingEdge; 1377 } 1378 1379 // leave room for bottom fading edge as long as rect isn't at very bottom 1380 if (rect.bottom < getChildAt(0).getHeight()) { 1381 screenBottom -= fadingEdge; 1382 } 1383 1384 int scrollYDelta = 0; 1385 1386 if (rect.bottom > screenBottom && rect.top > screenTop) { 1387 // need to move down to get it in view: move down just enough so 1388 // that the entire rectangle is in view (or at least the first 1389 // screen size chunk). 1390 1391 if (rect.height() > height) { 1392 // just enough to get screen size chunk on 1393 scrollYDelta += (rect.top - screenTop); 1394 } else { 1395 // get entire rect at bottom of screen 1396 scrollYDelta += (rect.bottom - screenBottom); 1397 } 1398 1399 // make sure we aren't scrolling beyond the end of our content 1400 int bottom = getChildAt(0).getBottom(); 1401 int distanceToBottom = bottom - screenBottom; 1402 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1403 1404 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1405 // need to move up to get it in view: move up just enough so that 1406 // entire rectangle is in view (or at least the first screen 1407 // size chunk of it). 1408 1409 if (rect.height() > height) { 1410 // screen size chunk 1411 scrollYDelta -= (screenBottom - rect.bottom); 1412 } else { 1413 // entire rect at top 1414 scrollYDelta -= (screenTop - rect.top); 1415 } 1416 1417 // make sure we aren't scrolling any further than the top our content 1418 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1419 } 1420 return scrollYDelta; 1421 } 1422 1423 @Override requestChildFocus(View child, View focused)1424 public void requestChildFocus(View child, View focused) { 1425 if (!mIsLayoutDirty) { 1426 scrollToChild(focused); 1427 } else { 1428 // The child may not be laid out yet, we can't compute the scroll yet 1429 mChildToScrollTo = focused; 1430 } 1431 super.requestChildFocus(child, focused); 1432 } 1433 1434 1435 /** 1436 * When looking for focus in children of a scroll view, need to be a little 1437 * more careful not to give focus to something that is scrolled off screen. 1438 * 1439 * This is more expensive than the default {@link android.view.ViewGroup} 1440 * implementation, otherwise this behavior might have been made the default. 1441 */ 1442 @Override onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect)1443 protected boolean onRequestFocusInDescendants(int direction, 1444 Rect previouslyFocusedRect) { 1445 1446 // convert from forward / backward notation to up / down / left / right 1447 // (ugh). 1448 if (direction == View.FOCUS_FORWARD) { 1449 direction = View.FOCUS_DOWN; 1450 } else if (direction == View.FOCUS_BACKWARD) { 1451 direction = View.FOCUS_UP; 1452 } 1453 1454 final View nextFocus = previouslyFocusedRect == null ? 1455 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1456 FocusFinder.getInstance().findNextFocusFromRect(this, 1457 previouslyFocusedRect, direction); 1458 1459 if (nextFocus == null) { 1460 return false; 1461 } 1462 1463 if (isOffScreen(nextFocus)) { 1464 return false; 1465 } 1466 1467 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1468 } 1469 1470 @Override requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate)1471 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1472 boolean immediate) { 1473 // offset into coordinate space of this scroll view 1474 rectangle.offset(child.getLeft() - child.getScrollX(), 1475 child.getTop() - child.getScrollY()); 1476 1477 return scrollToChildRect(rectangle, immediate); 1478 } 1479 1480 @Override requestLayout()1481 public void requestLayout() { 1482 mIsLayoutDirty = true; 1483 super.requestLayout(); 1484 } 1485 1486 @Override onDetachedFromWindow()1487 protected void onDetachedFromWindow() { 1488 super.onDetachedFromWindow(); 1489 1490 if (mScrollStrictSpan != null) { 1491 mScrollStrictSpan.finish(); 1492 mScrollStrictSpan = null; 1493 } 1494 if (mFlingStrictSpan != null) { 1495 mFlingStrictSpan.finish(); 1496 mFlingStrictSpan = null; 1497 } 1498 } 1499 1500 @Override onLayout(boolean changed, int l, int t, int r, int b)1501 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1502 super.onLayout(changed, l, t, r, b); 1503 mIsLayoutDirty = false; 1504 // Give a child focus if it needs it 1505 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1506 scrollToChild(mChildToScrollTo); 1507 } 1508 mChildToScrollTo = null; 1509 1510 if (!isLaidOut()) { 1511 if (mSavedState != null) { 1512 mScrollY = mSavedState.scrollPosition; 1513 mSavedState = null; 1514 } // mScrollY default value is "0" 1515 1516 final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; 1517 final int scrollRange = Math.max(0, 1518 childHeight - (b - t - mPaddingBottom - mPaddingTop)); 1519 1520 // Don't forget to clamp 1521 if (mScrollY > scrollRange) { 1522 mScrollY = scrollRange; 1523 } else if (mScrollY < 0) { 1524 mScrollY = 0; 1525 } 1526 } 1527 1528 // Calling this with the present values causes it to re-claim them 1529 scrollTo(mScrollX, mScrollY); 1530 } 1531 1532 @Override onSizeChanged(int w, int h, int oldw, int oldh)1533 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1534 super.onSizeChanged(w, h, oldw, oldh); 1535 1536 View currentFocused = findFocus(); 1537 if (null == currentFocused || this == currentFocused) 1538 return; 1539 1540 // If the currently-focused view was visible on the screen when the 1541 // screen was at the old height, then scroll the screen to make that 1542 // view visible with the new screen height. 1543 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1544 currentFocused.getDrawingRect(mTempRect); 1545 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1546 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1547 doScrollY(scrollDelta); 1548 } 1549 } 1550 1551 /** 1552 * Return true if child is a descendant of parent, (or equal to the parent). 1553 */ isViewDescendantOf(View child, View parent)1554 private static boolean isViewDescendantOf(View child, View parent) { 1555 if (child == parent) { 1556 return true; 1557 } 1558 1559 final ViewParent theParent = child.getParent(); 1560 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1561 } 1562 1563 /** 1564 * Fling the scroll view 1565 * 1566 * @param velocityY The initial velocity in the Y direction. Positive 1567 * numbers mean that the finger/cursor is moving down the screen, 1568 * which means we want to scroll towards the top. 1569 */ fling(int velocityY)1570 public void fling(int velocityY) { 1571 if (getChildCount() > 0) { 1572 int height = getHeight() - mPaddingBottom - mPaddingTop; 1573 int bottom = getChildAt(0).getHeight(); 1574 1575 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1576 Math.max(0, bottom - height), 0, height/2); 1577 1578 if (mFlingStrictSpan == null) { 1579 mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling"); 1580 } 1581 1582 postInvalidateOnAnimation(); 1583 } 1584 } 1585 flingWithNestedDispatch(int velocityY)1586 private void flingWithNestedDispatch(int velocityY) { 1587 final boolean canFling = (mScrollY > 0 || velocityY > 0) && 1588 (mScrollY < getScrollRange() || velocityY < 0); 1589 if (!dispatchNestedPreFling(0, velocityY)) { 1590 dispatchNestedFling(0, velocityY, canFling); 1591 if (canFling) { 1592 fling(velocityY); 1593 } 1594 } 1595 } 1596 endDrag()1597 private void endDrag() { 1598 mIsBeingDragged = false; 1599 1600 recycleVelocityTracker(); 1601 1602 if (mEdgeGlowTop != null) { 1603 mEdgeGlowTop.onRelease(); 1604 mEdgeGlowBottom.onRelease(); 1605 } 1606 1607 if (mScrollStrictSpan != null) { 1608 mScrollStrictSpan.finish(); 1609 mScrollStrictSpan = null; 1610 } 1611 } 1612 1613 /** 1614 * {@inheritDoc} 1615 * 1616 * <p>This version also clamps the scrolling to the bounds of our child. 1617 */ 1618 @Override scrollTo(int x, int y)1619 public void scrollTo(int x, int y) { 1620 // we rely on the fact the View.scrollBy calls scrollTo. 1621 if (getChildCount() > 0) { 1622 View child = getChildAt(0); 1623 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1624 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1625 if (x != mScrollX || y != mScrollY) { 1626 super.scrollTo(x, y); 1627 } 1628 } 1629 } 1630 1631 @Override setOverScrollMode(int mode)1632 public void setOverScrollMode(int mode) { 1633 if (mode != OVER_SCROLL_NEVER) { 1634 if (mEdgeGlowTop == null) { 1635 Context context = getContext(); 1636 mEdgeGlowTop = new EdgeEffect(context); 1637 mEdgeGlowBottom = new EdgeEffect(context); 1638 } 1639 } else { 1640 mEdgeGlowTop = null; 1641 mEdgeGlowBottom = null; 1642 } 1643 super.setOverScrollMode(mode); 1644 } 1645 1646 @Override onStartNestedScroll(View child, View target, int nestedScrollAxes)1647 public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { 1648 return (nestedScrollAxes & SCROLL_AXIS_VERTICAL) != 0; 1649 } 1650 1651 @Override onNestedScrollAccepted(View child, View target, int axes)1652 public void onNestedScrollAccepted(View child, View target, int axes) { 1653 super.onNestedScrollAccepted(child, target, axes); 1654 startNestedScroll(SCROLL_AXIS_VERTICAL); 1655 } 1656 1657 /** 1658 * @inheritDoc 1659 */ 1660 @Override onStopNestedScroll(View target)1661 public void onStopNestedScroll(View target) { 1662 super.onStopNestedScroll(target); 1663 } 1664 1665 @Override onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed)1666 public void onNestedScroll(View target, int dxConsumed, int dyConsumed, 1667 int dxUnconsumed, int dyUnconsumed) { 1668 final int oldScrollY = mScrollY; 1669 scrollBy(0, dyUnconsumed); 1670 final int myConsumed = mScrollY - oldScrollY; 1671 final int myUnconsumed = dyUnconsumed - myConsumed; 1672 dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null); 1673 } 1674 1675 /** 1676 * @inheritDoc 1677 */ 1678 @Override onNestedFling(View target, float velocityX, float velocityY, boolean consumed)1679 public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { 1680 if (!consumed) { 1681 flingWithNestedDispatch((int) velocityY); 1682 return true; 1683 } 1684 return false; 1685 } 1686 1687 @Override draw(Canvas canvas)1688 public void draw(Canvas canvas) { 1689 super.draw(canvas); 1690 if (mEdgeGlowTop != null) { 1691 final int scrollY = mScrollY; 1692 if (!mEdgeGlowTop.isFinished()) { 1693 final int restoreCount = canvas.save(); 1694 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1695 1696 canvas.translate(mPaddingLeft, Math.min(0, scrollY)); 1697 mEdgeGlowTop.setSize(width, getHeight()); 1698 if (mEdgeGlowTop.draw(canvas)) { 1699 postInvalidateOnAnimation(); 1700 } 1701 canvas.restoreToCount(restoreCount); 1702 } 1703 if (!mEdgeGlowBottom.isFinished()) { 1704 final int restoreCount = canvas.save(); 1705 final int width = getWidth() - mPaddingLeft - mPaddingRight; 1706 final int height = getHeight(); 1707 1708 canvas.translate(-width + mPaddingLeft, 1709 Math.max(getScrollRange(), scrollY) + height); 1710 canvas.rotate(180, width, 0); 1711 mEdgeGlowBottom.setSize(width, height); 1712 if (mEdgeGlowBottom.draw(canvas)) { 1713 postInvalidateOnAnimation(); 1714 } 1715 canvas.restoreToCount(restoreCount); 1716 } 1717 } 1718 } 1719 clamp(int n, int my, int child)1720 private static int clamp(int n, int my, int child) { 1721 if (my >= child || n < 0) { 1722 /* my >= child is this case: 1723 * |--------------- me ---------------| 1724 * |------ child ------| 1725 * or 1726 * |--------------- me ---------------| 1727 * |------ child ------| 1728 * or 1729 * |--------------- me ---------------| 1730 * |------ child ------| 1731 * 1732 * n < 0 is this case: 1733 * |------ me ------| 1734 * |-------- child --------| 1735 * |-- mScrollX --| 1736 */ 1737 return 0; 1738 } 1739 if ((my+n) > child) { 1740 /* this case: 1741 * |------ me ------| 1742 * |------ child ------| 1743 * |-- mScrollX --| 1744 */ 1745 return child-my; 1746 } 1747 return n; 1748 } 1749 1750 @Override onRestoreInstanceState(Parcelable state)1751 protected void onRestoreInstanceState(Parcelable state) { 1752 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1753 // Some old apps reused IDs in ways they shouldn't have. 1754 // Don't break them, but they don't get scroll state restoration. 1755 super.onRestoreInstanceState(state); 1756 return; 1757 } 1758 SavedState ss = (SavedState) state; 1759 super.onRestoreInstanceState(ss.getSuperState()); 1760 mSavedState = ss; 1761 requestLayout(); 1762 } 1763 1764 @Override onSaveInstanceState()1765 protected Parcelable onSaveInstanceState() { 1766 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1767 // Some old apps reused IDs in ways they shouldn't have. 1768 // Don't break them, but they don't get scroll state restoration. 1769 return super.onSaveInstanceState(); 1770 } 1771 Parcelable superState = super.onSaveInstanceState(); 1772 SavedState ss = new SavedState(superState); 1773 ss.scrollPosition = mScrollY; 1774 return ss; 1775 } 1776 1777 static class SavedState extends BaseSavedState { 1778 public int scrollPosition; 1779 SavedState(Parcelable superState)1780 SavedState(Parcelable superState) { 1781 super(superState); 1782 } 1783 SavedState(Parcel source)1784 public SavedState(Parcel source) { 1785 super(source); 1786 scrollPosition = source.readInt(); 1787 } 1788 1789 @Override writeToParcel(Parcel dest, int flags)1790 public void writeToParcel(Parcel dest, int flags) { 1791 super.writeToParcel(dest, flags); 1792 dest.writeInt(scrollPosition); 1793 } 1794 1795 @Override toString()1796 public String toString() { 1797 return "HorizontalScrollView.SavedState{" 1798 + Integer.toHexString(System.identityHashCode(this)) 1799 + " scrollPosition=" + scrollPosition + "}"; 1800 } 1801 1802 public static final Parcelable.Creator<SavedState> CREATOR 1803 = new Parcelable.Creator<SavedState>() { 1804 public SavedState createFromParcel(Parcel in) { 1805 return new SavedState(in); 1806 } 1807 1808 public SavedState[] newArray(int size) { 1809 return new SavedState[size]; 1810 } 1811 }; 1812 } 1813 1814 } 1815