1/* 2 * Copyright (C) 2015 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 18package android.support.v4.widget; 19 20import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP; 21 22import android.content.Context; 23import android.content.res.TypedArray; 24import android.graphics.Canvas; 25import android.graphics.Rect; 26import android.os.Bundle; 27import android.os.Parcel; 28import android.os.Parcelable; 29import android.support.annotation.RestrictTo; 30import android.support.v4.view.AccessibilityDelegateCompat; 31import android.support.v4.view.InputDeviceCompat; 32import android.support.v4.view.NestedScrollingChild2; 33import android.support.v4.view.NestedScrollingChildHelper; 34import android.support.v4.view.NestedScrollingParent; 35import android.support.v4.view.NestedScrollingParentHelper; 36import android.support.v4.view.ScrollingView; 37import android.support.v4.view.ViewCompat; 38import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; 39import android.support.v4.view.accessibility.AccessibilityRecordCompat; 40import android.util.AttributeSet; 41import android.util.Log; 42import android.util.TypedValue; 43import android.view.FocusFinder; 44import android.view.KeyEvent; 45import android.view.MotionEvent; 46import android.view.VelocityTracker; 47import android.view.View; 48import android.view.ViewConfiguration; 49import android.view.ViewGroup; 50import android.view.ViewParent; 51import android.view.accessibility.AccessibilityEvent; 52import android.view.animation.AnimationUtils; 53import android.widget.EdgeEffect; 54import android.widget.FrameLayout; 55import android.widget.OverScroller; 56import android.widget.ScrollView; 57 58import java.util.List; 59 60/** 61 * NestedScrollView is just like {@link android.widget.ScrollView}, but it supports acting 62 * as both a nested scrolling parent and child on both new and old versions of Android. 63 * Nested scrolling is enabled by default. 64 */ 65public class NestedScrollView extends FrameLayout implements NestedScrollingParent, 66 NestedScrollingChild2, ScrollingView { 67 static final int ANIMATED_SCROLL_GAP = 250; 68 69 static final float MAX_SCROLL_FACTOR = 0.5f; 70 71 private static final String TAG = "NestedScrollView"; 72 73 /** 74 * Interface definition for a callback to be invoked when the scroll 75 * X or Y positions of a view change. 76 * 77 * <p>This version of the interface works on all versions of Android, back to API v4.</p> 78 * 79 * @see #setOnScrollChangeListener(OnScrollChangeListener) 80 */ 81 public interface OnScrollChangeListener { 82 /** 83 * Called when the scroll position of a view changes. 84 * 85 * @param v The view whose scroll position has changed. 86 * @param scrollX Current horizontal scroll origin. 87 * @param scrollY Current vertical scroll origin. 88 * @param oldScrollX Previous horizontal scroll origin. 89 * @param oldScrollY Previous vertical scroll origin. 90 */ 91 void onScrollChange(NestedScrollView v, int scrollX, int scrollY, 92 int oldScrollX, int oldScrollY); 93 } 94 95 private long mLastScroll; 96 97 private final Rect mTempRect = new Rect(); 98 private OverScroller mScroller; 99 private EdgeEffect mEdgeGlowTop; 100 private EdgeEffect mEdgeGlowBottom; 101 102 /** 103 * Position of the last motion event. 104 */ 105 private int mLastMotionY; 106 107 /** 108 * True when the layout has changed but the traversal has not come through yet. 109 * Ideally the view hierarchy would keep track of this for us. 110 */ 111 private boolean mIsLayoutDirty = true; 112 private boolean mIsLaidOut = false; 113 114 /** 115 * The child to give focus to in the event that a child has requested focus while the 116 * layout is dirty. This prevents the scroll from being wrong if the child has not been 117 * laid out before requesting focus. 118 */ 119 private View mChildToScrollTo = null; 120 121 /** 122 * True if the user is currently dragging this ScrollView around. This is 123 * not the same as 'is being flinged', which can be checked by 124 * mScroller.isFinished() (flinging begins when the user lifts his finger). 125 */ 126 private boolean mIsBeingDragged = false; 127 128 /** 129 * Determines speed during touch scrolling 130 */ 131 private VelocityTracker mVelocityTracker; 132 133 /** 134 * When set to true, the scroll view measure its child to make it fill the currently 135 * visible area. 136 */ 137 private boolean mFillViewport; 138 139 /** 140 * Whether arrow scrolling is animated. 141 */ 142 private boolean mSmoothScrollingEnabled = true; 143 144 private int mTouchSlop; 145 private int mMinimumVelocity; 146 private int mMaximumVelocity; 147 148 /** 149 * ID of the active pointer. This is used to retain consistency during 150 * drags/flings if multiple pointers are used. 151 */ 152 private int mActivePointerId = INVALID_POINTER; 153 154 /** 155 * Used during scrolling to retrieve the new offset within the window. 156 */ 157 private final int[] mScrollOffset = new int[2]; 158 private final int[] mScrollConsumed = new int[2]; 159 private int mNestedYOffset; 160 161 private int mLastScrollerY; 162 163 /** 164 * Sentinel value for no current active pointer. 165 * Used by {@link #mActivePointerId}. 166 */ 167 private static final int INVALID_POINTER = -1; 168 169 private SavedState mSavedState; 170 171 private static final AccessibilityDelegate ACCESSIBILITY_DELEGATE = new AccessibilityDelegate(); 172 173 private static final int[] SCROLLVIEW_STYLEABLE = new int[] { 174 android.R.attr.fillViewport 175 }; 176 177 private final NestedScrollingParentHelper mParentHelper; 178 private final NestedScrollingChildHelper mChildHelper; 179 180 private float mVerticalScrollFactor; 181 182 private OnScrollChangeListener mOnScrollChangeListener; 183 184 public NestedScrollView(Context context) { 185 this(context, null); 186 } 187 188 public NestedScrollView(Context context, AttributeSet attrs) { 189 this(context, attrs, 0); 190 } 191 192 public NestedScrollView(Context context, AttributeSet attrs, int defStyleAttr) { 193 super(context, attrs, defStyleAttr); 194 initScrollView(); 195 196 final TypedArray a = context.obtainStyledAttributes( 197 attrs, SCROLLVIEW_STYLEABLE, defStyleAttr, 0); 198 199 setFillViewport(a.getBoolean(0, false)); 200 201 a.recycle(); 202 203 mParentHelper = new NestedScrollingParentHelper(this); 204 mChildHelper = new NestedScrollingChildHelper(this); 205 206 // ...because why else would you be using this widget? 207 setNestedScrollingEnabled(true); 208 209 ViewCompat.setAccessibilityDelegate(this, ACCESSIBILITY_DELEGATE); 210 } 211 212 // NestedScrollingChild 213 214 @Override 215 public void setNestedScrollingEnabled(boolean enabled) { 216 mChildHelper.setNestedScrollingEnabled(enabled); 217 } 218 219 @Override 220 public boolean isNestedScrollingEnabled() { 221 return mChildHelper.isNestedScrollingEnabled(); 222 } 223 224 @Override 225 public boolean startNestedScroll(int axes) { 226 return mChildHelper.startNestedScroll(axes); 227 } 228 229 @Override 230 public boolean startNestedScroll(int axes, int type) { 231 return mChildHelper.startNestedScroll(axes, type); 232 } 233 234 @Override 235 public void stopNestedScroll() { 236 mChildHelper.stopNestedScroll(); 237 } 238 239 @Override 240 public void stopNestedScroll(int type) { 241 mChildHelper.stopNestedScroll(type); 242 } 243 244 @Override 245 public boolean hasNestedScrollingParent() { 246 return mChildHelper.hasNestedScrollingParent(); 247 } 248 249 @Override 250 public boolean hasNestedScrollingParent(int type) { 251 return mChildHelper.hasNestedScrollingParent(type); 252 } 253 254 @Override 255 public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, 256 int dyUnconsumed, int[] offsetInWindow) { 257 return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, 258 offsetInWindow); 259 } 260 261 @Override 262 public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, 263 int dyUnconsumed, int[] offsetInWindow, int type) { 264 return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, 265 offsetInWindow, type); 266 } 267 268 @Override 269 public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) { 270 return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow); 271 } 272 273 @Override 274 public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow, 275 int type) { 276 return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow, type); 277 } 278 279 @Override 280 public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) { 281 return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed); 282 } 283 284 @Override 285 public boolean dispatchNestedPreFling(float velocityX, float velocityY) { 286 return mChildHelper.dispatchNestedPreFling(velocityX, velocityY); 287 } 288 289 // NestedScrollingParent 290 291 @Override 292 public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { 293 return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0; 294 } 295 296 @Override 297 public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes) { 298 mParentHelper.onNestedScrollAccepted(child, target, nestedScrollAxes); 299 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 300 } 301 302 @Override 303 public void onStopNestedScroll(View target) { 304 mParentHelper.onStopNestedScroll(target); 305 stopNestedScroll(); 306 } 307 308 @Override 309 public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, 310 int dyUnconsumed) { 311 final int oldScrollY = getScrollY(); 312 scrollBy(0, dyUnconsumed); 313 final int myConsumed = getScrollY() - oldScrollY; 314 final int myUnconsumed = dyUnconsumed - myConsumed; 315 dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null); 316 } 317 318 @Override 319 public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { 320 dispatchNestedPreScroll(dx, dy, consumed, null); 321 } 322 323 @Override 324 public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { 325 if (!consumed) { 326 flingWithNestedDispatch((int) velocityY); 327 return true; 328 } 329 return false; 330 } 331 332 @Override 333 public boolean onNestedPreFling(View target, float velocityX, float velocityY) { 334 return dispatchNestedPreFling(velocityX, velocityY); 335 } 336 337 @Override 338 public int getNestedScrollAxes() { 339 return mParentHelper.getNestedScrollAxes(); 340 } 341 342 // ScrollView import 343 344 @Override 345 public boolean shouldDelayChildPressedState() { 346 return true; 347 } 348 349 @Override 350 protected float getTopFadingEdgeStrength() { 351 if (getChildCount() == 0) { 352 return 0.0f; 353 } 354 355 final int length = getVerticalFadingEdgeLength(); 356 final int scrollY = getScrollY(); 357 if (scrollY < length) { 358 return scrollY / (float) length; 359 } 360 361 return 1.0f; 362 } 363 364 @Override 365 protected float getBottomFadingEdgeStrength() { 366 if (getChildCount() == 0) { 367 return 0.0f; 368 } 369 370 final int length = getVerticalFadingEdgeLength(); 371 final int bottomEdge = getHeight() - getPaddingBottom(); 372 final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge; 373 if (span < length) { 374 return span / (float) length; 375 } 376 377 return 1.0f; 378 } 379 380 /** 381 * @return The maximum amount this scroll view will scroll in response to 382 * an arrow event. 383 */ 384 public int getMaxScrollAmount() { 385 return (int) (MAX_SCROLL_FACTOR * getHeight()); 386 } 387 388 private void initScrollView() { 389 mScroller = new OverScroller(getContext()); 390 setFocusable(true); 391 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 392 setWillNotDraw(false); 393 final ViewConfiguration configuration = ViewConfiguration.get(getContext()); 394 mTouchSlop = configuration.getScaledTouchSlop(); 395 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 396 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 397 } 398 399 @Override 400 public void addView(View child) { 401 if (getChildCount() > 0) { 402 throw new IllegalStateException("ScrollView can host only one direct child"); 403 } 404 405 super.addView(child); 406 } 407 408 @Override 409 public void addView(View child, int index) { 410 if (getChildCount() > 0) { 411 throw new IllegalStateException("ScrollView can host only one direct child"); 412 } 413 414 super.addView(child, index); 415 } 416 417 @Override 418 public void addView(View child, ViewGroup.LayoutParams params) { 419 if (getChildCount() > 0) { 420 throw new IllegalStateException("ScrollView can host only one direct child"); 421 } 422 423 super.addView(child, params); 424 } 425 426 @Override 427 public void addView(View child, int index, ViewGroup.LayoutParams params) { 428 if (getChildCount() > 0) { 429 throw new IllegalStateException("ScrollView can host only one direct child"); 430 } 431 432 super.addView(child, index, params); 433 } 434 435 /** 436 * Register a callback to be invoked when the scroll X or Y positions of 437 * this view change. 438 * <p>This version of the method works on all versions of Android, back to API v4.</p> 439 * 440 * @param l The listener to notify when the scroll X or Y position changes. 441 * @see android.view.View#getScrollX() 442 * @see android.view.View#getScrollY() 443 */ 444 public void setOnScrollChangeListener(OnScrollChangeListener l) { 445 mOnScrollChangeListener = l; 446 } 447 448 /** 449 * @return Returns true this ScrollView can be scrolled 450 */ 451 private boolean canScroll() { 452 View child = getChildAt(0); 453 if (child != null) { 454 int childHeight = child.getHeight(); 455 return getHeight() < childHeight + getPaddingTop() + getPaddingBottom(); 456 } 457 return false; 458 } 459 460 /** 461 * Indicates whether this ScrollView's content is stretched to fill the viewport. 462 * 463 * @return True if the content fills the viewport, false otherwise. 464 * 465 * @attr name android:fillViewport 466 */ 467 public boolean isFillViewport() { 468 return mFillViewport; 469 } 470 471 /** 472 * Set whether this ScrollView should stretch its content height to fill the viewport or not. 473 * 474 * @param fillViewport True to stretch the content's height to the viewport's 475 * boundaries, false otherwise. 476 * 477 * @attr name android:fillViewport 478 */ 479 public void setFillViewport(boolean fillViewport) { 480 if (fillViewport != mFillViewport) { 481 mFillViewport = fillViewport; 482 requestLayout(); 483 } 484 } 485 486 /** 487 * @return Whether arrow scrolling will animate its transition. 488 */ 489 public boolean isSmoothScrollingEnabled() { 490 return mSmoothScrollingEnabled; 491 } 492 493 /** 494 * Set whether arrow scrolling will animate its transition. 495 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 496 */ 497 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 498 mSmoothScrollingEnabled = smoothScrollingEnabled; 499 } 500 501 @Override 502 protected void onScrollChanged(int l, int t, int oldl, int oldt) { 503 super.onScrollChanged(l, t, oldl, oldt); 504 505 if (mOnScrollChangeListener != null) { 506 mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt); 507 } 508 } 509 510 @Override 511 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 512 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 513 514 if (!mFillViewport) { 515 return; 516 } 517 518 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 519 if (heightMode == MeasureSpec.UNSPECIFIED) { 520 return; 521 } 522 523 if (getChildCount() > 0) { 524 final View child = getChildAt(0); 525 int height = getMeasuredHeight(); 526 if (child.getMeasuredHeight() < height) { 527 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 528 529 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 530 getPaddingLeft() + getPaddingRight(), lp.width); 531 height -= getPaddingTop(); 532 height -= getPaddingBottom(); 533 int childHeightMeasureSpec = 534 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 535 536 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 537 } 538 } 539 } 540 541 @Override 542 public boolean dispatchKeyEvent(KeyEvent event) { 543 // Let the focused view and/or our descendants get the key first 544 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 545 } 546 547 /** 548 * You can call this function yourself to have the scroll view perform 549 * scrolling from a key event, just as if the event had been dispatched to 550 * it by the view hierarchy. 551 * 552 * @param event The key event to execute. 553 * @return Return true if the event was handled, else false. 554 */ 555 public boolean executeKeyEvent(KeyEvent event) { 556 mTempRect.setEmpty(); 557 558 if (!canScroll()) { 559 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 560 View currentFocused = findFocus(); 561 if (currentFocused == this) currentFocused = null; 562 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 563 currentFocused, View.FOCUS_DOWN); 564 return nextFocused != null 565 && nextFocused != this 566 && nextFocused.requestFocus(View.FOCUS_DOWN); 567 } 568 return false; 569 } 570 571 boolean handled = false; 572 if (event.getAction() == KeyEvent.ACTION_DOWN) { 573 switch (event.getKeyCode()) { 574 case KeyEvent.KEYCODE_DPAD_UP: 575 if (!event.isAltPressed()) { 576 handled = arrowScroll(View.FOCUS_UP); 577 } else { 578 handled = fullScroll(View.FOCUS_UP); 579 } 580 break; 581 case KeyEvent.KEYCODE_DPAD_DOWN: 582 if (!event.isAltPressed()) { 583 handled = arrowScroll(View.FOCUS_DOWN); 584 } else { 585 handled = fullScroll(View.FOCUS_DOWN); 586 } 587 break; 588 case KeyEvent.KEYCODE_SPACE: 589 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 590 break; 591 } 592 } 593 594 return handled; 595 } 596 597 private boolean inChild(int x, int y) { 598 if (getChildCount() > 0) { 599 final int scrollY = getScrollY(); 600 final View child = getChildAt(0); 601 return !(y < child.getTop() - scrollY 602 || y >= child.getBottom() - scrollY 603 || x < child.getLeft() 604 || x >= child.getRight()); 605 } 606 return false; 607 } 608 609 private void initOrResetVelocityTracker() { 610 if (mVelocityTracker == null) { 611 mVelocityTracker = VelocityTracker.obtain(); 612 } else { 613 mVelocityTracker.clear(); 614 } 615 } 616 617 private void initVelocityTrackerIfNotExists() { 618 if (mVelocityTracker == null) { 619 mVelocityTracker = VelocityTracker.obtain(); 620 } 621 } 622 623 private void recycleVelocityTracker() { 624 if (mVelocityTracker != null) { 625 mVelocityTracker.recycle(); 626 mVelocityTracker = null; 627 } 628 } 629 630 @Override 631 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 632 if (disallowIntercept) { 633 recycleVelocityTracker(); 634 } 635 super.requestDisallowInterceptTouchEvent(disallowIntercept); 636 } 637 638 @Override 639 public boolean onInterceptTouchEvent(MotionEvent ev) { 640 /* 641 * This method JUST determines whether we want to intercept the motion. 642 * If we return true, onMotionEvent will be called and we do the actual 643 * scrolling there. 644 */ 645 646 /* 647 * Shortcut the most recurring case: the user is in the dragging 648 * state and he is moving his finger. We want to intercept this 649 * motion. 650 */ 651 final int action = ev.getAction(); 652 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 653 return true; 654 } 655 656 switch (action & MotionEvent.ACTION_MASK) { 657 case MotionEvent.ACTION_MOVE: { 658 /* 659 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 660 * whether the user has moved far enough from his original down touch. 661 */ 662 663 /* 664 * Locally do absolute value. mLastMotionY is set to the y value 665 * of the down event. 666 */ 667 final int activePointerId = mActivePointerId; 668 if (activePointerId == INVALID_POINTER) { 669 // If we don't have a valid id, the touch down wasn't on content. 670 break; 671 } 672 673 final int pointerIndex = ev.findPointerIndex(activePointerId); 674 if (pointerIndex == -1) { 675 Log.e(TAG, "Invalid pointerId=" + activePointerId 676 + " in onInterceptTouchEvent"); 677 break; 678 } 679 680 final int y = (int) ev.getY(pointerIndex); 681 final int yDiff = Math.abs(y - mLastMotionY); 682 if (yDiff > mTouchSlop 683 && (getNestedScrollAxes() & ViewCompat.SCROLL_AXIS_VERTICAL) == 0) { 684 mIsBeingDragged = true; 685 mLastMotionY = y; 686 initVelocityTrackerIfNotExists(); 687 mVelocityTracker.addMovement(ev); 688 mNestedYOffset = 0; 689 final ViewParent parent = getParent(); 690 if (parent != null) { 691 parent.requestDisallowInterceptTouchEvent(true); 692 } 693 } 694 break; 695 } 696 697 case MotionEvent.ACTION_DOWN: { 698 final int y = (int) ev.getY(); 699 if (!inChild((int) ev.getX(), y)) { 700 mIsBeingDragged = false; 701 recycleVelocityTracker(); 702 break; 703 } 704 705 /* 706 * Remember location of down touch. 707 * ACTION_DOWN always refers to pointer index 0. 708 */ 709 mLastMotionY = y; 710 mActivePointerId = ev.getPointerId(0); 711 712 initOrResetVelocityTracker(); 713 mVelocityTracker.addMovement(ev); 714 /* 715 * If being flinged and user touches the screen, initiate drag; 716 * otherwise don't. mScroller.isFinished should be false when 717 * being flinged. We need to call computeScrollOffset() first so that 718 * isFinished() is correct. 719 */ 720 mScroller.computeScrollOffset(); 721 mIsBeingDragged = !mScroller.isFinished(); 722 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, ViewCompat.TYPE_TOUCH); 723 break; 724 } 725 726 case MotionEvent.ACTION_CANCEL: 727 case MotionEvent.ACTION_UP: 728 /* Release the drag */ 729 mIsBeingDragged = false; 730 mActivePointerId = INVALID_POINTER; 731 recycleVelocityTracker(); 732 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { 733 ViewCompat.postInvalidateOnAnimation(this); 734 } 735 stopNestedScroll(ViewCompat.TYPE_TOUCH); 736 break; 737 case MotionEvent.ACTION_POINTER_UP: 738 onSecondaryPointerUp(ev); 739 break; 740 } 741 742 /* 743 * The only time we want to intercept motion events is if we are in the 744 * drag mode. 745 */ 746 return mIsBeingDragged; 747 } 748 749 @Override 750 public boolean onTouchEvent(MotionEvent ev) { 751 initVelocityTrackerIfNotExists(); 752 753 MotionEvent vtev = MotionEvent.obtain(ev); 754 755 final int actionMasked = ev.getActionMasked(); 756 757 if (actionMasked == MotionEvent.ACTION_DOWN) { 758 mNestedYOffset = 0; 759 } 760 vtev.offsetLocation(0, mNestedYOffset); 761 762 switch (actionMasked) { 763 case MotionEvent.ACTION_DOWN: { 764 if (getChildCount() == 0) { 765 return false; 766 } 767 if ((mIsBeingDragged = !mScroller.isFinished())) { 768 final ViewParent parent = getParent(); 769 if (parent != null) { 770 parent.requestDisallowInterceptTouchEvent(true); 771 } 772 } 773 774 /* 775 * If being flinged and user touches, stop the fling. isFinished 776 * will be false if being flinged. 777 */ 778 if (!mScroller.isFinished()) { 779 mScroller.abortAnimation(); 780 } 781 782 // Remember where the motion event started 783 mLastMotionY = (int) ev.getY(); 784 mActivePointerId = ev.getPointerId(0); 785 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, ViewCompat.TYPE_TOUCH); 786 break; 787 } 788 case MotionEvent.ACTION_MOVE: 789 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 790 if (activePointerIndex == -1) { 791 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 792 break; 793 } 794 795 final int y = (int) ev.getY(activePointerIndex); 796 int deltaY = mLastMotionY - y; 797 if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset, 798 ViewCompat.TYPE_TOUCH)) { 799 deltaY -= mScrollConsumed[1]; 800 vtev.offsetLocation(0, mScrollOffset[1]); 801 mNestedYOffset += mScrollOffset[1]; 802 } 803 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 804 final ViewParent parent = getParent(); 805 if (parent != null) { 806 parent.requestDisallowInterceptTouchEvent(true); 807 } 808 mIsBeingDragged = true; 809 if (deltaY > 0) { 810 deltaY -= mTouchSlop; 811 } else { 812 deltaY += mTouchSlop; 813 } 814 } 815 if (mIsBeingDragged) { 816 // Scroll to follow the motion event 817 mLastMotionY = y - mScrollOffset[1]; 818 819 final int oldY = getScrollY(); 820 final int range = getScrollRange(); 821 final int overscrollMode = getOverScrollMode(); 822 boolean canOverscroll = overscrollMode == View.OVER_SCROLL_ALWAYS 823 || (overscrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 824 825 // Calling overScrollByCompat will call onOverScrolled, which 826 // calls onScrollChanged if applicable. 827 if (overScrollByCompat(0, deltaY, 0, getScrollY(), 0, range, 0, 828 0, true) && !hasNestedScrollingParent(ViewCompat.TYPE_TOUCH)) { 829 // Break our velocity if we hit a scroll barrier. 830 mVelocityTracker.clear(); 831 } 832 833 final int scrolledDeltaY = getScrollY() - oldY; 834 final int unconsumedY = deltaY - scrolledDeltaY; 835 if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset, 836 ViewCompat.TYPE_TOUCH)) { 837 mLastMotionY -= mScrollOffset[1]; 838 vtev.offsetLocation(0, mScrollOffset[1]); 839 mNestedYOffset += mScrollOffset[1]; 840 } else if (canOverscroll) { 841 ensureGlows(); 842 final int pulledToY = oldY + deltaY; 843 if (pulledToY < 0) { 844 EdgeEffectCompat.onPull(mEdgeGlowTop, (float) deltaY / getHeight(), 845 ev.getX(activePointerIndex) / getWidth()); 846 if (!mEdgeGlowBottom.isFinished()) { 847 mEdgeGlowBottom.onRelease(); 848 } 849 } else if (pulledToY > range) { 850 EdgeEffectCompat.onPull(mEdgeGlowBottom, (float) deltaY / getHeight(), 851 1.f - ev.getX(activePointerIndex) 852 / getWidth()); 853 if (!mEdgeGlowTop.isFinished()) { 854 mEdgeGlowTop.onRelease(); 855 } 856 } 857 if (mEdgeGlowTop != null 858 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 859 ViewCompat.postInvalidateOnAnimation(this); 860 } 861 } 862 } 863 break; 864 case MotionEvent.ACTION_UP: 865 final VelocityTracker velocityTracker = mVelocityTracker; 866 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 867 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 868 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 869 flingWithNestedDispatch(-initialVelocity); 870 } else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 871 getScrollRange())) { 872 ViewCompat.postInvalidateOnAnimation(this); 873 } 874 mActivePointerId = INVALID_POINTER; 875 endDrag(); 876 break; 877 case MotionEvent.ACTION_CANCEL: 878 if (mIsBeingDragged && getChildCount() > 0) { 879 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 880 getScrollRange())) { 881 ViewCompat.postInvalidateOnAnimation(this); 882 } 883 } 884 mActivePointerId = INVALID_POINTER; 885 endDrag(); 886 break; 887 case MotionEvent.ACTION_POINTER_DOWN: { 888 final int index = ev.getActionIndex(); 889 mLastMotionY = (int) ev.getY(index); 890 mActivePointerId = ev.getPointerId(index); 891 break; 892 } 893 case MotionEvent.ACTION_POINTER_UP: 894 onSecondaryPointerUp(ev); 895 mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId)); 896 break; 897 } 898 899 if (mVelocityTracker != null) { 900 mVelocityTracker.addMovement(vtev); 901 } 902 vtev.recycle(); 903 return true; 904 } 905 906 private void onSecondaryPointerUp(MotionEvent ev) { 907 final int pointerIndex = ev.getActionIndex(); 908 final int pointerId = ev.getPointerId(pointerIndex); 909 if (pointerId == mActivePointerId) { 910 // This was our active pointer going up. Choose a new 911 // active pointer and adjust accordingly. 912 // TODO: Make this decision more intelligent. 913 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 914 mLastMotionY = (int) ev.getY(newPointerIndex); 915 mActivePointerId = ev.getPointerId(newPointerIndex); 916 if (mVelocityTracker != null) { 917 mVelocityTracker.clear(); 918 } 919 } 920 } 921 922 @Override 923 public boolean onGenericMotionEvent(MotionEvent event) { 924 if ((event.getSource() & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) { 925 switch (event.getAction()) { 926 case MotionEvent.ACTION_SCROLL: { 927 if (!mIsBeingDragged) { 928 final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); 929 if (vscroll != 0) { 930 final int delta = (int) (vscroll * getVerticalScrollFactorCompat()); 931 final int range = getScrollRange(); 932 int oldScrollY = getScrollY(); 933 int newScrollY = oldScrollY - delta; 934 if (newScrollY < 0) { 935 newScrollY = 0; 936 } else if (newScrollY > range) { 937 newScrollY = range; 938 } 939 if (newScrollY != oldScrollY) { 940 super.scrollTo(getScrollX(), newScrollY); 941 return true; 942 } 943 } 944 } 945 } 946 } 947 } 948 return false; 949 } 950 951 private float getVerticalScrollFactorCompat() { 952 if (mVerticalScrollFactor == 0) { 953 TypedValue outValue = new TypedValue(); 954 final Context context = getContext(); 955 if (!context.getTheme().resolveAttribute( 956 android.R.attr.listPreferredItemHeight, outValue, true)) { 957 throw new IllegalStateException( 958 "Expected theme to define listPreferredItemHeight."); 959 } 960 mVerticalScrollFactor = outValue.getDimension( 961 context.getResources().getDisplayMetrics()); 962 } 963 return mVerticalScrollFactor; 964 } 965 966 @Override 967 protected void onOverScrolled(int scrollX, int scrollY, 968 boolean clampedX, boolean clampedY) { 969 super.scrollTo(scrollX, scrollY); 970 } 971 972 boolean overScrollByCompat(int deltaX, int deltaY, 973 int scrollX, int scrollY, 974 int scrollRangeX, int scrollRangeY, 975 int maxOverScrollX, int maxOverScrollY, 976 boolean isTouchEvent) { 977 final int overScrollMode = getOverScrollMode(); 978 final boolean canScrollHorizontal = 979 computeHorizontalScrollRange() > computeHorizontalScrollExtent(); 980 final boolean canScrollVertical = 981 computeVerticalScrollRange() > computeVerticalScrollExtent(); 982 final boolean overScrollHorizontal = overScrollMode == View.OVER_SCROLL_ALWAYS 983 || (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal); 984 final boolean overScrollVertical = overScrollMode == View.OVER_SCROLL_ALWAYS 985 || (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical); 986 987 int newScrollX = scrollX + deltaX; 988 if (!overScrollHorizontal) { 989 maxOverScrollX = 0; 990 } 991 992 int newScrollY = scrollY + deltaY; 993 if (!overScrollVertical) { 994 maxOverScrollY = 0; 995 } 996 997 // Clamp values if at the limits and record 998 final int left = -maxOverScrollX; 999 final int right = maxOverScrollX + scrollRangeX; 1000 final int top = -maxOverScrollY; 1001 final int bottom = maxOverScrollY + scrollRangeY; 1002 1003 boolean clampedX = false; 1004 if (newScrollX > right) { 1005 newScrollX = right; 1006 clampedX = true; 1007 } else if (newScrollX < left) { 1008 newScrollX = left; 1009 clampedX = true; 1010 } 1011 1012 boolean clampedY = false; 1013 if (newScrollY > bottom) { 1014 newScrollY = bottom; 1015 clampedY = true; 1016 } else if (newScrollY < top) { 1017 newScrollY = top; 1018 clampedY = true; 1019 } 1020 1021 if (clampedY && !hasNestedScrollingParent(ViewCompat.TYPE_NON_TOUCH)) { 1022 mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange()); 1023 } 1024 1025 onOverScrolled(newScrollX, newScrollY, clampedX, clampedY); 1026 1027 return clampedX || clampedY; 1028 } 1029 1030 int getScrollRange() { 1031 int scrollRange = 0; 1032 if (getChildCount() > 0) { 1033 View child = getChildAt(0); 1034 scrollRange = Math.max(0, 1035 child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop())); 1036 } 1037 return scrollRange; 1038 } 1039 1040 /** 1041 * <p> 1042 * Finds the next focusable component that fits in the specified bounds. 1043 * </p> 1044 * 1045 * @param topFocus look for a candidate is the one at the top of the bounds 1046 * if topFocus is true, or at the bottom of the bounds if topFocus is 1047 * false 1048 * @param top the top offset of the bounds in which a focusable must be 1049 * found 1050 * @param bottom the bottom offset of the bounds in which a focusable must 1051 * be found 1052 * @return the next focusable component in the bounds or null if none can 1053 * be found 1054 */ 1055 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 1056 1057 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 1058 View focusCandidate = null; 1059 1060 /* 1061 * A fully contained focusable is one where its top is below the bound's 1062 * top, and its bottom is above the bound's bottom. A partially 1063 * contained focusable is one where some part of it is within the 1064 * bounds, but it also has some part that is not within bounds. A fully contained 1065 * focusable is preferred to a partially contained focusable. 1066 */ 1067 boolean foundFullyContainedFocusable = false; 1068 1069 int count = focusables.size(); 1070 for (int i = 0; i < count; i++) { 1071 View view = focusables.get(i); 1072 int viewTop = view.getTop(); 1073 int viewBottom = view.getBottom(); 1074 1075 if (top < viewBottom && viewTop < bottom) { 1076 /* 1077 * the focusable is in the target area, it is a candidate for 1078 * focusing 1079 */ 1080 1081 final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom); 1082 1083 if (focusCandidate == null) { 1084 /* No candidate, take this one */ 1085 focusCandidate = view; 1086 foundFullyContainedFocusable = viewIsFullyContained; 1087 } else { 1088 final boolean viewIsCloserToBoundary = 1089 (topFocus && viewTop < focusCandidate.getTop()) 1090 || (!topFocus && viewBottom > focusCandidate.getBottom()); 1091 1092 if (foundFullyContainedFocusable) { 1093 if (viewIsFullyContained && viewIsCloserToBoundary) { 1094 /* 1095 * We're dealing with only fully contained views, so 1096 * it has to be closer to the boundary to beat our 1097 * candidate 1098 */ 1099 focusCandidate = view; 1100 } 1101 } else { 1102 if (viewIsFullyContained) { 1103 /* Any fully contained view beats a partially contained view */ 1104 focusCandidate = view; 1105 foundFullyContainedFocusable = true; 1106 } else if (viewIsCloserToBoundary) { 1107 /* 1108 * Partially contained view beats another partially 1109 * contained view if it's closer 1110 */ 1111 focusCandidate = view; 1112 } 1113 } 1114 } 1115 } 1116 } 1117 1118 return focusCandidate; 1119 } 1120 1121 /** 1122 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 1123 * method will scroll the view by one page up or down and give the focus 1124 * to the topmost/bottommost component in the new visible area. If no 1125 * component is a good candidate for focus, this scrollview reclaims the 1126 * focus.</p> 1127 * 1128 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1129 * to go one page up or 1130 * {@link android.view.View#FOCUS_DOWN} to go one page down 1131 * @return true if the key event is consumed by this method, false otherwise 1132 */ 1133 public boolean pageScroll(int direction) { 1134 boolean down = direction == View.FOCUS_DOWN; 1135 int height = getHeight(); 1136 1137 if (down) { 1138 mTempRect.top = getScrollY() + height; 1139 int count = getChildCount(); 1140 if (count > 0) { 1141 View view = getChildAt(count - 1); 1142 if (mTempRect.top + height > view.getBottom()) { 1143 mTempRect.top = view.getBottom() - height; 1144 } 1145 } 1146 } else { 1147 mTempRect.top = getScrollY() - height; 1148 if (mTempRect.top < 0) { 1149 mTempRect.top = 0; 1150 } 1151 } 1152 mTempRect.bottom = mTempRect.top + height; 1153 1154 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1155 } 1156 1157 /** 1158 * <p>Handles scrolling in response to a "home/end" shortcut press. This 1159 * method will scroll the view to the top or bottom and give the focus 1160 * to the topmost/bottommost component in the new visible area. If no 1161 * component is a good candidate for focus, this scrollview reclaims the 1162 * focus.</p> 1163 * 1164 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1165 * to go the top of the view or 1166 * {@link android.view.View#FOCUS_DOWN} to go the bottom 1167 * @return true if the key event is consumed by this method, false otherwise 1168 */ 1169 public boolean fullScroll(int direction) { 1170 boolean down = direction == View.FOCUS_DOWN; 1171 int height = getHeight(); 1172 1173 mTempRect.top = 0; 1174 mTempRect.bottom = height; 1175 1176 if (down) { 1177 int count = getChildCount(); 1178 if (count > 0) { 1179 View view = getChildAt(count - 1); 1180 mTempRect.bottom = view.getBottom() + getPaddingBottom(); 1181 mTempRect.top = mTempRect.bottom - height; 1182 } 1183 } 1184 1185 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1186 } 1187 1188 /** 1189 * <p>Scrolls the view to make the area defined by <code>top</code> and 1190 * <code>bottom</code> visible. This method attempts to give the focus 1191 * to a component visible in this area. If no component can be focused in 1192 * the new visible area, the focus is reclaimed by this ScrollView.</p> 1193 * 1194 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1195 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 1196 * @param top the top offset of the new area to be made visible 1197 * @param bottom the bottom offset of the new area to be made visible 1198 * @return true if the key event is consumed by this method, false otherwise 1199 */ 1200 private boolean scrollAndFocus(int direction, int top, int bottom) { 1201 boolean handled = true; 1202 1203 int height = getHeight(); 1204 int containerTop = getScrollY(); 1205 int containerBottom = containerTop + height; 1206 boolean up = direction == View.FOCUS_UP; 1207 1208 View newFocused = findFocusableViewInBounds(up, top, bottom); 1209 if (newFocused == null) { 1210 newFocused = this; 1211 } 1212 1213 if (top >= containerTop && bottom <= containerBottom) { 1214 handled = false; 1215 } else { 1216 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1217 doScrollY(delta); 1218 } 1219 1220 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1221 1222 return handled; 1223 } 1224 1225 /** 1226 * Handle scrolling in response to an up or down arrow click. 1227 * 1228 * @param direction The direction corresponding to the arrow key that was 1229 * pressed 1230 * @return True if we consumed the event, false otherwise 1231 */ 1232 public boolean arrowScroll(int direction) { 1233 1234 View currentFocused = findFocus(); 1235 if (currentFocused == this) currentFocused = null; 1236 1237 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1238 1239 final int maxJump = getMaxScrollAmount(); 1240 1241 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1242 nextFocused.getDrawingRect(mTempRect); 1243 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1244 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1245 doScrollY(scrollDelta); 1246 nextFocused.requestFocus(direction); 1247 } else { 1248 // no new focus 1249 int scrollDelta = maxJump; 1250 1251 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1252 scrollDelta = getScrollY(); 1253 } else if (direction == View.FOCUS_DOWN) { 1254 if (getChildCount() > 0) { 1255 int daBottom = getChildAt(0).getBottom(); 1256 int screenBottom = getScrollY() + getHeight() - getPaddingBottom(); 1257 if (daBottom - screenBottom < maxJump) { 1258 scrollDelta = daBottom - screenBottom; 1259 } 1260 } 1261 } 1262 if (scrollDelta == 0) { 1263 return false; 1264 } 1265 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1266 } 1267 1268 if (currentFocused != null && currentFocused.isFocused() 1269 && isOffScreen(currentFocused)) { 1270 // previously focused item still has focus and is off screen, give 1271 // it up (take it back to ourselves) 1272 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1273 // sure to 1274 // get it) 1275 final int descendantFocusability = getDescendantFocusability(); // save 1276 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1277 requestFocus(); 1278 setDescendantFocusability(descendantFocusability); // restore 1279 } 1280 return true; 1281 } 1282 1283 /** 1284 * @return whether the descendant of this scroll view is scrolled off 1285 * screen. 1286 */ 1287 private boolean isOffScreen(View descendant) { 1288 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1289 } 1290 1291 /** 1292 * @return whether the descendant of this scroll view is within delta 1293 * pixels of being on the screen. 1294 */ 1295 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1296 descendant.getDrawingRect(mTempRect); 1297 offsetDescendantRectToMyCoords(descendant, mTempRect); 1298 1299 return (mTempRect.bottom + delta) >= getScrollY() 1300 && (mTempRect.top - delta) <= (getScrollY() + height); 1301 } 1302 1303 /** 1304 * Smooth scroll by a Y delta 1305 * 1306 * @param delta the number of pixels to scroll by on the Y axis 1307 */ 1308 private void doScrollY(int delta) { 1309 if (delta != 0) { 1310 if (mSmoothScrollingEnabled) { 1311 smoothScrollBy(0, delta); 1312 } else { 1313 scrollBy(0, delta); 1314 } 1315 } 1316 } 1317 1318 /** 1319 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1320 * 1321 * @param dx the number of pixels to scroll by on the X axis 1322 * @param dy the number of pixels to scroll by on the Y axis 1323 */ 1324 public final void smoothScrollBy(int dx, int dy) { 1325 if (getChildCount() == 0) { 1326 // Nothing to do. 1327 return; 1328 } 1329 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1330 if (duration > ANIMATED_SCROLL_GAP) { 1331 final int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1332 final int bottom = getChildAt(0).getHeight(); 1333 final int maxY = Math.max(0, bottom - height); 1334 final int scrollY = getScrollY(); 1335 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1336 1337 mScroller.startScroll(getScrollX(), scrollY, 0, dy); 1338 ViewCompat.postInvalidateOnAnimation(this); 1339 } else { 1340 if (!mScroller.isFinished()) { 1341 mScroller.abortAnimation(); 1342 } 1343 scrollBy(dx, dy); 1344 } 1345 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1346 } 1347 1348 /** 1349 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1350 * 1351 * @param x the position where to scroll on the X axis 1352 * @param y the position where to scroll on the Y axis 1353 */ 1354 public final void smoothScrollTo(int x, int y) { 1355 smoothScrollBy(x - getScrollX(), y - getScrollY()); 1356 } 1357 1358 /** 1359 * <p>The scroll range of a scroll view is the overall height of all of its 1360 * children.</p> 1361 * @hide 1362 */ 1363 @RestrictTo(LIBRARY_GROUP) 1364 @Override 1365 public int computeVerticalScrollRange() { 1366 final int count = getChildCount(); 1367 final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop(); 1368 if (count == 0) { 1369 return contentHeight; 1370 } 1371 1372 int scrollRange = getChildAt(0).getBottom(); 1373 final int scrollY = getScrollY(); 1374 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1375 if (scrollY < 0) { 1376 scrollRange -= scrollY; 1377 } else if (scrollY > overscrollBottom) { 1378 scrollRange += scrollY - overscrollBottom; 1379 } 1380 1381 return scrollRange; 1382 } 1383 1384 /** @hide */ 1385 @RestrictTo(LIBRARY_GROUP) 1386 @Override 1387 public int computeVerticalScrollOffset() { 1388 return Math.max(0, super.computeVerticalScrollOffset()); 1389 } 1390 1391 /** @hide */ 1392 @RestrictTo(LIBRARY_GROUP) 1393 @Override 1394 public int computeVerticalScrollExtent() { 1395 return super.computeVerticalScrollExtent(); 1396 } 1397 1398 /** @hide */ 1399 @RestrictTo(LIBRARY_GROUP) 1400 @Override 1401 public int computeHorizontalScrollRange() { 1402 return super.computeHorizontalScrollRange(); 1403 } 1404 1405 /** @hide */ 1406 @RestrictTo(LIBRARY_GROUP) 1407 @Override 1408 public int computeHorizontalScrollOffset() { 1409 return super.computeHorizontalScrollOffset(); 1410 } 1411 1412 /** @hide */ 1413 @RestrictTo(LIBRARY_GROUP) 1414 @Override 1415 public int computeHorizontalScrollExtent() { 1416 return super.computeHorizontalScrollExtent(); 1417 } 1418 1419 @Override 1420 protected void measureChild(View child, int parentWidthMeasureSpec, 1421 int parentHeightMeasureSpec) { 1422 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1423 1424 int childWidthMeasureSpec; 1425 int childHeightMeasureSpec; 1426 1427 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() 1428 + getPaddingRight(), lp.width); 1429 1430 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1431 1432 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1433 } 1434 1435 @Override 1436 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1437 int parentHeightMeasureSpec, int heightUsed) { 1438 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1439 1440 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1441 getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin 1442 + widthUsed, lp.width); 1443 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1444 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1445 1446 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1447 } 1448 1449 @Override 1450 public void computeScroll() { 1451 if (mScroller.computeScrollOffset()) { 1452 final int x = mScroller.getCurrX(); 1453 final int y = mScroller.getCurrY(); 1454 1455 int dy = y - mLastScrollerY; 1456 1457 // Dispatch up to parent 1458 if (dispatchNestedPreScroll(0, dy, mScrollConsumed, null, ViewCompat.TYPE_NON_TOUCH)) { 1459 dy -= mScrollConsumed[1]; 1460 } 1461 1462 if (dy != 0) { 1463 final int range = getScrollRange(); 1464 final int oldScrollY = getScrollY(); 1465 1466 overScrollByCompat(0, dy, getScrollX(), oldScrollY, 0, range, 0, 0, false); 1467 1468 final int scrolledDeltaY = getScrollY() - oldScrollY; 1469 final int unconsumedY = dy - scrolledDeltaY; 1470 1471 if (!dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, null, 1472 ViewCompat.TYPE_NON_TOUCH)) { 1473 final int mode = getOverScrollMode(); 1474 final boolean canOverscroll = mode == OVER_SCROLL_ALWAYS 1475 || (mode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1476 if (canOverscroll) { 1477 ensureGlows(); 1478 if (y <= 0 && oldScrollY > 0) { 1479 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1480 } else if (y >= range && oldScrollY < range) { 1481 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1482 } 1483 } 1484 } 1485 } 1486 1487 // Finally update the scroll positions and post an invalidation 1488 mLastScrollerY = y; 1489 ViewCompat.postInvalidateOnAnimation(this); 1490 } else { 1491 // We can't scroll any more, so stop any indirect scrolling 1492 if (hasNestedScrollingParent(ViewCompat.TYPE_NON_TOUCH)) { 1493 stopNestedScroll(ViewCompat.TYPE_NON_TOUCH); 1494 } 1495 // and reset the scroller y 1496 mLastScrollerY = 0; 1497 } 1498 } 1499 1500 /** 1501 * Scrolls the view to the given child. 1502 * 1503 * @param child the View to scroll to 1504 */ 1505 private void scrollToChild(View child) { 1506 child.getDrawingRect(mTempRect); 1507 1508 /* Offset from child's local coordinates to ScrollView coordinates */ 1509 offsetDescendantRectToMyCoords(child, mTempRect); 1510 1511 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1512 1513 if (scrollDelta != 0) { 1514 scrollBy(0, scrollDelta); 1515 } 1516 } 1517 1518 /** 1519 * If rect is off screen, scroll just enough to get it (or at least the 1520 * first screen size chunk of it) on screen. 1521 * 1522 * @param rect The rectangle. 1523 * @param immediate True to scroll immediately without animation 1524 * @return true if scrolling was performed 1525 */ 1526 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1527 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1528 final boolean scroll = delta != 0; 1529 if (scroll) { 1530 if (immediate) { 1531 scrollBy(0, delta); 1532 } else { 1533 smoothScrollBy(0, delta); 1534 } 1535 } 1536 return scroll; 1537 } 1538 1539 /** 1540 * Compute the amount to scroll in the Y direction in order to get 1541 * a rectangle completely on the screen (or, if taller than the screen, 1542 * at least the first screen size chunk of it). 1543 * 1544 * @param rect The rect. 1545 * @return The scroll delta. 1546 */ 1547 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1548 if (getChildCount() == 0) return 0; 1549 1550 int height = getHeight(); 1551 int screenTop = getScrollY(); 1552 int screenBottom = screenTop + height; 1553 1554 int fadingEdge = getVerticalFadingEdgeLength(); 1555 1556 // leave room for top fading edge as long as rect isn't at very top 1557 if (rect.top > 0) { 1558 screenTop += fadingEdge; 1559 } 1560 1561 // leave room for bottom fading edge as long as rect isn't at very bottom 1562 if (rect.bottom < getChildAt(0).getHeight()) { 1563 screenBottom -= fadingEdge; 1564 } 1565 1566 int scrollYDelta = 0; 1567 1568 if (rect.bottom > screenBottom && rect.top > screenTop) { 1569 // need to move down to get it in view: move down just enough so 1570 // that the entire rectangle is in view (or at least the first 1571 // screen size chunk). 1572 1573 if (rect.height() > height) { 1574 // just enough to get screen size chunk on 1575 scrollYDelta += (rect.top - screenTop); 1576 } else { 1577 // get entire rect at bottom of screen 1578 scrollYDelta += (rect.bottom - screenBottom); 1579 } 1580 1581 // make sure we aren't scrolling beyond the end of our content 1582 int bottom = getChildAt(0).getBottom(); 1583 int distanceToBottom = bottom - screenBottom; 1584 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1585 1586 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1587 // need to move up to get it in view: move up just enough so that 1588 // entire rectangle is in view (or at least the first screen 1589 // size chunk of it). 1590 1591 if (rect.height() > height) { 1592 // screen size chunk 1593 scrollYDelta -= (screenBottom - rect.bottom); 1594 } else { 1595 // entire rect at top 1596 scrollYDelta -= (screenTop - rect.top); 1597 } 1598 1599 // make sure we aren't scrolling any further than the top our content 1600 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1601 } 1602 return scrollYDelta; 1603 } 1604 1605 @Override 1606 public void requestChildFocus(View child, View focused) { 1607 if (!mIsLayoutDirty) { 1608 scrollToChild(focused); 1609 } else { 1610 // The child may not be laid out yet, we can't compute the scroll yet 1611 mChildToScrollTo = focused; 1612 } 1613 super.requestChildFocus(child, focused); 1614 } 1615 1616 1617 /** 1618 * When looking for focus in children of a scroll view, need to be a little 1619 * more careful not to give focus to something that is scrolled off screen. 1620 * 1621 * This is more expensive than the default {@link android.view.ViewGroup} 1622 * implementation, otherwise this behavior might have been made the default. 1623 */ 1624 @Override 1625 protected boolean onRequestFocusInDescendants(int direction, 1626 Rect previouslyFocusedRect) { 1627 1628 // convert from forward / backward notation to up / down / left / right 1629 // (ugh). 1630 if (direction == View.FOCUS_FORWARD) { 1631 direction = View.FOCUS_DOWN; 1632 } else if (direction == View.FOCUS_BACKWARD) { 1633 direction = View.FOCUS_UP; 1634 } 1635 1636 final View nextFocus = previouslyFocusedRect == null 1637 ? FocusFinder.getInstance().findNextFocus(this, null, direction) 1638 : FocusFinder.getInstance().findNextFocusFromRect( 1639 this, previouslyFocusedRect, direction); 1640 1641 if (nextFocus == null) { 1642 return false; 1643 } 1644 1645 if (isOffScreen(nextFocus)) { 1646 return false; 1647 } 1648 1649 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1650 } 1651 1652 @Override 1653 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1654 boolean immediate) { 1655 // offset into coordinate space of this scroll view 1656 rectangle.offset(child.getLeft() - child.getScrollX(), 1657 child.getTop() - child.getScrollY()); 1658 1659 return scrollToChildRect(rectangle, immediate); 1660 } 1661 1662 @Override 1663 public void requestLayout() { 1664 mIsLayoutDirty = true; 1665 super.requestLayout(); 1666 } 1667 1668 @Override 1669 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1670 super.onLayout(changed, l, t, r, b); 1671 mIsLayoutDirty = false; 1672 // Give a child focus if it needs it 1673 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1674 scrollToChild(mChildToScrollTo); 1675 } 1676 mChildToScrollTo = null; 1677 1678 if (!mIsLaidOut) { 1679 if (mSavedState != null) { 1680 scrollTo(getScrollX(), mSavedState.scrollPosition); 1681 mSavedState = null; 1682 } // mScrollY default value is "0" 1683 1684 final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; 1685 final int scrollRange = Math.max(0, 1686 childHeight - (b - t - getPaddingBottom() - getPaddingTop())); 1687 1688 // Don't forget to clamp 1689 if (getScrollY() > scrollRange) { 1690 scrollTo(getScrollX(), scrollRange); 1691 } else if (getScrollY() < 0) { 1692 scrollTo(getScrollX(), 0); 1693 } 1694 } 1695 1696 // Calling this with the present values causes it to re-claim them 1697 scrollTo(getScrollX(), getScrollY()); 1698 mIsLaidOut = true; 1699 } 1700 1701 @Override 1702 public void onAttachedToWindow() { 1703 super.onAttachedToWindow(); 1704 1705 mIsLaidOut = false; 1706 } 1707 1708 @Override 1709 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1710 super.onSizeChanged(w, h, oldw, oldh); 1711 1712 View currentFocused = findFocus(); 1713 if (null == currentFocused || this == currentFocused) { 1714 return; 1715 } 1716 1717 // If the currently-focused view was visible on the screen when the 1718 // screen was at the old height, then scroll the screen to make that 1719 // view visible with the new screen height. 1720 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1721 currentFocused.getDrawingRect(mTempRect); 1722 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1723 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1724 doScrollY(scrollDelta); 1725 } 1726 } 1727 1728 /** 1729 * Return true if child is a descendant of parent, (or equal to the parent). 1730 */ 1731 private static boolean isViewDescendantOf(View child, View parent) { 1732 if (child == parent) { 1733 return true; 1734 } 1735 1736 final ViewParent theParent = child.getParent(); 1737 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1738 } 1739 1740 /** 1741 * Fling the scroll view 1742 * 1743 * @param velocityY The initial velocity in the Y direction. Positive 1744 * numbers mean that the finger/cursor is moving down the screen, 1745 * which means we want to scroll towards the top. 1746 */ 1747 public void fling(int velocityY) { 1748 if (getChildCount() > 0) { 1749 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, ViewCompat.TYPE_NON_TOUCH); 1750 mScroller.fling(getScrollX(), getScrollY(), // start 1751 0, velocityY, // velocities 1752 0, 0, // x 1753 Integer.MIN_VALUE, Integer.MAX_VALUE, // y 1754 0, 0); // overscroll 1755 mLastScrollerY = getScrollY(); 1756 ViewCompat.postInvalidateOnAnimation(this); 1757 } 1758 } 1759 1760 private void flingWithNestedDispatch(int velocityY) { 1761 final int scrollY = getScrollY(); 1762 final boolean canFling = (scrollY > 0 || velocityY > 0) 1763 && (scrollY < getScrollRange() || velocityY < 0); 1764 if (!dispatchNestedPreFling(0, velocityY)) { 1765 dispatchNestedFling(0, velocityY, canFling); 1766 fling(velocityY); 1767 } 1768 } 1769 1770 private void endDrag() { 1771 mIsBeingDragged = false; 1772 1773 recycleVelocityTracker(); 1774 stopNestedScroll(ViewCompat.TYPE_TOUCH); 1775 1776 if (mEdgeGlowTop != null) { 1777 mEdgeGlowTop.onRelease(); 1778 mEdgeGlowBottom.onRelease(); 1779 } 1780 } 1781 1782 /** 1783 * {@inheritDoc} 1784 * 1785 * <p>This version also clamps the scrolling to the bounds of our child. 1786 */ 1787 @Override 1788 public void scrollTo(int x, int y) { 1789 // we rely on the fact the View.scrollBy calls scrollTo. 1790 if (getChildCount() > 0) { 1791 View child = getChildAt(0); 1792 x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); 1793 y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); 1794 if (x != getScrollX() || y != getScrollY()) { 1795 super.scrollTo(x, y); 1796 } 1797 } 1798 } 1799 1800 private void ensureGlows() { 1801 if (getOverScrollMode() != View.OVER_SCROLL_NEVER) { 1802 if (mEdgeGlowTop == null) { 1803 Context context = getContext(); 1804 mEdgeGlowTop = new EdgeEffect(context); 1805 mEdgeGlowBottom = new EdgeEffect(context); 1806 } 1807 } else { 1808 mEdgeGlowTop = null; 1809 mEdgeGlowBottom = null; 1810 } 1811 } 1812 1813 @Override 1814 public void draw(Canvas canvas) { 1815 super.draw(canvas); 1816 if (mEdgeGlowTop != null) { 1817 final int scrollY = getScrollY(); 1818 if (!mEdgeGlowTop.isFinished()) { 1819 final int restoreCount = canvas.save(); 1820 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1821 1822 canvas.translate(getPaddingLeft(), Math.min(0, scrollY)); 1823 mEdgeGlowTop.setSize(width, getHeight()); 1824 if (mEdgeGlowTop.draw(canvas)) { 1825 ViewCompat.postInvalidateOnAnimation(this); 1826 } 1827 canvas.restoreToCount(restoreCount); 1828 } 1829 if (!mEdgeGlowBottom.isFinished()) { 1830 final int restoreCount = canvas.save(); 1831 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1832 final int height = getHeight(); 1833 1834 canvas.translate(-width + getPaddingLeft(), 1835 Math.max(getScrollRange(), scrollY) + height); 1836 canvas.rotate(180, width, 0); 1837 mEdgeGlowBottom.setSize(width, height); 1838 if (mEdgeGlowBottom.draw(canvas)) { 1839 ViewCompat.postInvalidateOnAnimation(this); 1840 } 1841 canvas.restoreToCount(restoreCount); 1842 } 1843 } 1844 } 1845 1846 private static int clamp(int n, int my, int child) { 1847 if (my >= child || n < 0) { 1848 /* my >= child is this case: 1849 * |--------------- me ---------------| 1850 * |------ child ------| 1851 * or 1852 * |--------------- me ---------------| 1853 * |------ child ------| 1854 * or 1855 * |--------------- me ---------------| 1856 * |------ child ------| 1857 * 1858 * n < 0 is this case: 1859 * |------ me ------| 1860 * |-------- child --------| 1861 * |-- mScrollX --| 1862 */ 1863 return 0; 1864 } 1865 if ((my + n) > child) { 1866 /* this case: 1867 * |------ me ------| 1868 * |------ child ------| 1869 * |-- mScrollX --| 1870 */ 1871 return child - my; 1872 } 1873 return n; 1874 } 1875 1876 @Override 1877 protected void onRestoreInstanceState(Parcelable state) { 1878 if (!(state instanceof SavedState)) { 1879 super.onRestoreInstanceState(state); 1880 return; 1881 } 1882 1883 SavedState ss = (SavedState) state; 1884 super.onRestoreInstanceState(ss.getSuperState()); 1885 mSavedState = ss; 1886 requestLayout(); 1887 } 1888 1889 @Override 1890 protected Parcelable onSaveInstanceState() { 1891 Parcelable superState = super.onSaveInstanceState(); 1892 SavedState ss = new SavedState(superState); 1893 ss.scrollPosition = getScrollY(); 1894 return ss; 1895 } 1896 1897 static class SavedState extends BaseSavedState { 1898 public int scrollPosition; 1899 1900 SavedState(Parcelable superState) { 1901 super(superState); 1902 } 1903 1904 SavedState(Parcel source) { 1905 super(source); 1906 scrollPosition = source.readInt(); 1907 } 1908 1909 @Override 1910 public void writeToParcel(Parcel dest, int flags) { 1911 super.writeToParcel(dest, flags); 1912 dest.writeInt(scrollPosition); 1913 } 1914 1915 @Override 1916 public String toString() { 1917 return "HorizontalScrollView.SavedState{" 1918 + Integer.toHexString(System.identityHashCode(this)) 1919 + " scrollPosition=" + scrollPosition + "}"; 1920 } 1921 1922 public static final Parcelable.Creator<SavedState> CREATOR = 1923 new Parcelable.Creator<SavedState>() { 1924 @Override 1925 public SavedState createFromParcel(Parcel in) { 1926 return new SavedState(in); 1927 } 1928 1929 @Override 1930 public SavedState[] newArray(int size) { 1931 return new SavedState[size]; 1932 } 1933 }; 1934 } 1935 1936 static class AccessibilityDelegate extends AccessibilityDelegateCompat { 1937 @Override 1938 public boolean performAccessibilityAction(View host, int action, Bundle arguments) { 1939 if (super.performAccessibilityAction(host, action, arguments)) { 1940 return true; 1941 } 1942 final NestedScrollView nsvHost = (NestedScrollView) host; 1943 if (!nsvHost.isEnabled()) { 1944 return false; 1945 } 1946 switch (action) { 1947 case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: { 1948 final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() 1949 - nsvHost.getPaddingTop(); 1950 final int targetScrollY = Math.min(nsvHost.getScrollY() + viewportHeight, 1951 nsvHost.getScrollRange()); 1952 if (targetScrollY != nsvHost.getScrollY()) { 1953 nsvHost.smoothScrollTo(0, targetScrollY); 1954 return true; 1955 } 1956 } 1957 return false; 1958 case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: { 1959 final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() 1960 - nsvHost.getPaddingTop(); 1961 final int targetScrollY = Math.max(nsvHost.getScrollY() - viewportHeight, 0); 1962 if (targetScrollY != nsvHost.getScrollY()) { 1963 nsvHost.smoothScrollTo(0, targetScrollY); 1964 return true; 1965 } 1966 } 1967 return false; 1968 } 1969 return false; 1970 } 1971 1972 @Override 1973 public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { 1974 super.onInitializeAccessibilityNodeInfo(host, info); 1975 final NestedScrollView nsvHost = (NestedScrollView) host; 1976 info.setClassName(ScrollView.class.getName()); 1977 if (nsvHost.isEnabled()) { 1978 final int scrollRange = nsvHost.getScrollRange(); 1979 if (scrollRange > 0) { 1980 info.setScrollable(true); 1981 if (nsvHost.getScrollY() > 0) { 1982 info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); 1983 } 1984 if (nsvHost.getScrollY() < scrollRange) { 1985 info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); 1986 } 1987 } 1988 } 1989 } 1990 1991 @Override 1992 public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { 1993 super.onInitializeAccessibilityEvent(host, event); 1994 final NestedScrollView nsvHost = (NestedScrollView) host; 1995 event.setClassName(ScrollView.class.getName()); 1996 final boolean scrollable = nsvHost.getScrollRange() > 0; 1997 event.setScrollable(scrollable); 1998 event.setScrollX(nsvHost.getScrollX()); 1999 event.setScrollY(nsvHost.getScrollY()); 2000 AccessibilityRecordCompat.setMaxScrollX(event, nsvHost.getScrollX()); 2001 AccessibilityRecordCompat.setMaxScrollY(event, nsvHost.getScrollRange()); 2002 } 2003 } 2004} 2005