NestedScrollView.java revision 6ed40c1f86bcb172a1f0f069cde1c571a7781aee
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.NestedScrollingChild; 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.AccessibilityEventCompat; 39import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; 40import android.support.v4.view.accessibility.AccessibilityRecordCompat; 41import android.util.AttributeSet; 42import android.util.Log; 43import android.util.TypedValue; 44import android.view.FocusFinder; 45import android.view.KeyEvent; 46import android.view.MotionEvent; 47import android.view.VelocityTracker; 48import android.view.View; 49import android.view.ViewConfiguration; 50import android.view.ViewGroup; 51import android.view.ViewParent; 52import android.view.accessibility.AccessibilityEvent; 53import android.view.animation.AnimationUtils; 54import android.widget.FrameLayout; 55import android.widget.ScrollView; 56 57import java.util.List; 58 59/** 60 * NestedScrollView is just like {@link android.widget.ScrollView}, but it supports acting 61 * as both a nested scrolling parent and child on both new and old versions of Android. 62 * Nested scrolling is enabled by default. 63 */ 64public class NestedScrollView extends FrameLayout implements NestedScrollingParent, 65 NestedScrollingChild, ScrollingView { 66 static final int ANIMATED_SCROLL_GAP = 250; 67 68 static final float MAX_SCROLL_FACTOR = 0.5f; 69 70 private static final String TAG = "NestedScrollView"; 71 72 /** 73 * Interface definition for a callback to be invoked when the scroll 74 * X or Y positions of a view change. 75 * 76 * <p>This version of the interface works on all versions of Android, back to API v4.</p> 77 * 78 * @see #setOnScrollChangeListener(OnScrollChangeListener) 79 */ 80 public interface OnScrollChangeListener { 81 /** 82 * Called when the scroll position of a view changes. 83 * 84 * @param v The view whose scroll position has changed. 85 * @param scrollX Current horizontal scroll origin. 86 * @param scrollY Current vertical scroll origin. 87 * @param oldScrollX Previous horizontal scroll origin. 88 * @param oldScrollY Previous vertical scroll origin. 89 */ 90 void onScrollChange(NestedScrollView v, int scrollX, int scrollY, 91 int oldScrollX, int oldScrollY); 92 } 93 94 private long mLastScroll; 95 96 private final Rect mTempRect = new Rect(); 97 private ScrollerCompat mScroller; 98 private EdgeEffectCompat mEdgeGlowTop; 99 private EdgeEffectCompat mEdgeGlowBottom; 100 101 /** 102 * Position of the last motion event. 103 */ 104 private int mLastMotionY; 105 106 /** 107 * True when the layout has changed but the traversal has not come through yet. 108 * Ideally the view hierarchy would keep track of this for us. 109 */ 110 private boolean mIsLayoutDirty = true; 111 private boolean mIsLaidOut = false; 112 113 /** 114 * The child to give focus to in the event that a child has requested focus while the 115 * layout is dirty. This prevents the scroll from being wrong if the child has not been 116 * laid out before requesting focus. 117 */ 118 private View mChildToScrollTo = null; 119 120 /** 121 * True if the user is currently dragging this ScrollView around. This is 122 * not the same as 'is being flinged', which can be checked by 123 * mScroller.isFinished() (flinging begins when the user lifts his finger). 124 */ 125 private boolean mIsBeingDragged = false; 126 127 /** 128 * Determines speed during touch scrolling 129 */ 130 private VelocityTracker mVelocityTracker; 131 132 /** 133 * When set to true, the scroll view measure its child to make it fill the currently 134 * visible area. 135 */ 136 private boolean mFillViewport; 137 138 /** 139 * Whether arrow scrolling is animated. 140 */ 141 private boolean mSmoothScrollingEnabled = true; 142 143 private int mTouchSlop; 144 private int mMinimumVelocity; 145 private int mMaximumVelocity; 146 147 /** 148 * ID of the active pointer. This is used to retain consistency during 149 * drags/flings if multiple pointers are used. 150 */ 151 private int mActivePointerId = INVALID_POINTER; 152 153 /** 154 * Used during scrolling to retrieve the new offset within the window. 155 */ 156 private final int[] mScrollOffset = new int[2]; 157 private final int[] mScrollConsumed = new int[2]; 158 private int mNestedYOffset; 159 160 /** 161 * Sentinel value for no current active pointer. 162 * Used by {@link #mActivePointerId}. 163 */ 164 private static final int INVALID_POINTER = -1; 165 166 private SavedState mSavedState; 167 168 private static final AccessibilityDelegate ACCESSIBILITY_DELEGATE = new AccessibilityDelegate(); 169 170 private static final int[] SCROLLVIEW_STYLEABLE = new int[] { 171 android.R.attr.fillViewport 172 }; 173 174 private final NestedScrollingParentHelper mParentHelper; 175 private final NestedScrollingChildHelper mChildHelper; 176 177 private float mVerticalScrollFactor; 178 179 private OnScrollChangeListener mOnScrollChangeListener; 180 181 public NestedScrollView(Context context) { 182 this(context, null); 183 } 184 185 public NestedScrollView(Context context, AttributeSet attrs) { 186 this(context, attrs, 0); 187 } 188 189 public NestedScrollView(Context context, AttributeSet attrs, int defStyleAttr) { 190 super(context, attrs, defStyleAttr); 191 initScrollView(); 192 193 final TypedArray a = context.obtainStyledAttributes( 194 attrs, SCROLLVIEW_STYLEABLE, defStyleAttr, 0); 195 196 setFillViewport(a.getBoolean(0, false)); 197 198 a.recycle(); 199 200 mParentHelper = new NestedScrollingParentHelper(this); 201 mChildHelper = new NestedScrollingChildHelper(this); 202 203 // ...because why else would you be using this widget? 204 setNestedScrollingEnabled(true); 205 206 ViewCompat.setAccessibilityDelegate(this, ACCESSIBILITY_DELEGATE); 207 } 208 209 // NestedScrollingChild 210 211 @Override 212 public void setNestedScrollingEnabled(boolean enabled) { 213 mChildHelper.setNestedScrollingEnabled(enabled); 214 } 215 216 @Override 217 public boolean isNestedScrollingEnabled() { 218 return mChildHelper.isNestedScrollingEnabled(); 219 } 220 221 @Override 222 public boolean startNestedScroll(int axes) { 223 return mChildHelper.startNestedScroll(axes); 224 } 225 226 @Override 227 public void stopNestedScroll() { 228 mChildHelper.stopNestedScroll(); 229 } 230 231 @Override 232 public boolean hasNestedScrollingParent() { 233 return mChildHelper.hasNestedScrollingParent(); 234 } 235 236 @Override 237 public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, 238 int dyUnconsumed, int[] offsetInWindow) { 239 return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, 240 offsetInWindow); 241 } 242 243 @Override 244 public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) { 245 return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow); 246 } 247 248 @Override 249 public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) { 250 return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed); 251 } 252 253 @Override 254 public boolean dispatchNestedPreFling(float velocityX, float velocityY) { 255 return mChildHelper.dispatchNestedPreFling(velocityX, velocityY); 256 } 257 258 // NestedScrollingParent 259 260 @Override 261 public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { 262 return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0; 263 } 264 265 @Override 266 public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes) { 267 mParentHelper.onNestedScrollAccepted(child, target, nestedScrollAxes); 268 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 269 } 270 271 @Override 272 public void onStopNestedScroll(View target) { 273 mParentHelper.onStopNestedScroll(target); 274 stopNestedScroll(); 275 } 276 277 @Override 278 public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, 279 int dyUnconsumed) { 280 final int oldScrollY = getScrollY(); 281 scrollBy(0, dyUnconsumed); 282 final int myConsumed = getScrollY() - oldScrollY; 283 final int myUnconsumed = dyUnconsumed - myConsumed; 284 dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null); 285 } 286 287 @Override 288 public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { 289 dispatchNestedPreScroll(dx, dy, consumed, null); 290 } 291 292 @Override 293 public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { 294 if (!consumed) { 295 flingWithNestedDispatch((int) velocityY); 296 return true; 297 } 298 return false; 299 } 300 301 @Override 302 public boolean onNestedPreFling(View target, float velocityX, float velocityY) { 303 return dispatchNestedPreFling(velocityX, velocityY); 304 } 305 306 @Override 307 public int getNestedScrollAxes() { 308 return mParentHelper.getNestedScrollAxes(); 309 } 310 311 // ScrollView import 312 313 public boolean shouldDelayChildPressedState() { 314 return true; 315 } 316 317 @Override 318 protected float getTopFadingEdgeStrength() { 319 if (getChildCount() == 0) { 320 return 0.0f; 321 } 322 323 final int length = getVerticalFadingEdgeLength(); 324 final int scrollY = getScrollY(); 325 if (scrollY < length) { 326 return scrollY / (float) length; 327 } 328 329 return 1.0f; 330 } 331 332 @Override 333 protected float getBottomFadingEdgeStrength() { 334 if (getChildCount() == 0) { 335 return 0.0f; 336 } 337 338 final int length = getVerticalFadingEdgeLength(); 339 final int bottomEdge = getHeight() - getPaddingBottom(); 340 final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge; 341 if (span < length) { 342 return span / (float) length; 343 } 344 345 return 1.0f; 346 } 347 348 /** 349 * @return The maximum amount this scroll view will scroll in response to 350 * an arrow event. 351 */ 352 public int getMaxScrollAmount() { 353 return (int) (MAX_SCROLL_FACTOR * getHeight()); 354 } 355 356 private void initScrollView() { 357 mScroller = ScrollerCompat.create(getContext(), null); 358 setFocusable(true); 359 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 360 setWillNotDraw(false); 361 final ViewConfiguration configuration = ViewConfiguration.get(getContext()); 362 mTouchSlop = configuration.getScaledTouchSlop(); 363 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 364 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 365 } 366 367 @Override 368 public void addView(View child) { 369 if (getChildCount() > 0) { 370 throw new IllegalStateException("ScrollView can host only one direct child"); 371 } 372 373 super.addView(child); 374 } 375 376 @Override 377 public void addView(View child, int index) { 378 if (getChildCount() > 0) { 379 throw new IllegalStateException("ScrollView can host only one direct child"); 380 } 381 382 super.addView(child, index); 383 } 384 385 @Override 386 public void addView(View child, ViewGroup.LayoutParams params) { 387 if (getChildCount() > 0) { 388 throw new IllegalStateException("ScrollView can host only one direct child"); 389 } 390 391 super.addView(child, params); 392 } 393 394 @Override 395 public void addView(View child, int index, ViewGroup.LayoutParams params) { 396 if (getChildCount() > 0) { 397 throw new IllegalStateException("ScrollView can host only one direct child"); 398 } 399 400 super.addView(child, index, params); 401 } 402 403 /** 404 * Register a callback to be invoked when the scroll X or Y positions of 405 * this view change. 406 * <p>This version of the method works on all versions of Android, back to API v4.</p> 407 * 408 * @param l The listener to notify when the scroll X or Y position changes. 409 * @see android.view.View#getScrollX() 410 * @see android.view.View#getScrollY() 411 */ 412 public void setOnScrollChangeListener(OnScrollChangeListener l) { 413 mOnScrollChangeListener = l; 414 } 415 416 /** 417 * @return Returns true this ScrollView can be scrolled 418 */ 419 private boolean canScroll() { 420 View child = getChildAt(0); 421 if (child != null) { 422 int childHeight = child.getHeight(); 423 return getHeight() < childHeight + getPaddingTop() + getPaddingBottom(); 424 } 425 return false; 426 } 427 428 /** 429 * Indicates whether this ScrollView's content is stretched to fill the viewport. 430 * 431 * @return True if the content fills the viewport, false otherwise. 432 * 433 * @attr name android:fillViewport 434 */ 435 public boolean isFillViewport() { 436 return mFillViewport; 437 } 438 439 /** 440 * Set whether this ScrollView should stretch its content height to fill the viewport or not. 441 * 442 * @param fillViewport True to stretch the content's height to the viewport's 443 * boundaries, false otherwise. 444 * 445 * @attr name android:fillViewport 446 */ 447 public void setFillViewport(boolean fillViewport) { 448 if (fillViewport != mFillViewport) { 449 mFillViewport = fillViewport; 450 requestLayout(); 451 } 452 } 453 454 /** 455 * @return Whether arrow scrolling will animate its transition. 456 */ 457 public boolean isSmoothScrollingEnabled() { 458 return mSmoothScrollingEnabled; 459 } 460 461 /** 462 * Set whether arrow scrolling will animate its transition. 463 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 464 */ 465 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 466 mSmoothScrollingEnabled = smoothScrollingEnabled; 467 } 468 469 @Override 470 protected void onScrollChanged(int l, int t, int oldl, int oldt) { 471 super.onScrollChanged(l, t, oldl, oldt); 472 473 if (mOnScrollChangeListener != null) { 474 mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt); 475 } 476 } 477 478 @Override 479 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 480 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 481 482 if (!mFillViewport) { 483 return; 484 } 485 486 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 487 if (heightMode == MeasureSpec.UNSPECIFIED) { 488 return; 489 } 490 491 if (getChildCount() > 0) { 492 final View child = getChildAt(0); 493 int height = getMeasuredHeight(); 494 if (child.getMeasuredHeight() < height) { 495 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 496 497 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 498 getPaddingLeft() + getPaddingRight(), lp.width); 499 height -= getPaddingTop(); 500 height -= getPaddingBottom(); 501 int childHeightMeasureSpec = 502 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 503 504 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 505 } 506 } 507 } 508 509 @Override 510 public boolean dispatchKeyEvent(KeyEvent event) { 511 // Let the focused view and/or our descendants get the key first 512 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 513 } 514 515 /** 516 * You can call this function yourself to have the scroll view perform 517 * scrolling from a key event, just as if the event had been dispatched to 518 * it by the view hierarchy. 519 * 520 * @param event The key event to execute. 521 * @return Return true if the event was handled, else false. 522 */ 523 public boolean executeKeyEvent(KeyEvent event) { 524 mTempRect.setEmpty(); 525 526 if (!canScroll()) { 527 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 528 View currentFocused = findFocus(); 529 if (currentFocused == this) currentFocused = null; 530 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 531 currentFocused, View.FOCUS_DOWN); 532 return nextFocused != null 533 && nextFocused != this 534 && nextFocused.requestFocus(View.FOCUS_DOWN); 535 } 536 return false; 537 } 538 539 boolean handled = false; 540 if (event.getAction() == KeyEvent.ACTION_DOWN) { 541 switch (event.getKeyCode()) { 542 case KeyEvent.KEYCODE_DPAD_UP: 543 if (!event.isAltPressed()) { 544 handled = arrowScroll(View.FOCUS_UP); 545 } else { 546 handled = fullScroll(View.FOCUS_UP); 547 } 548 break; 549 case KeyEvent.KEYCODE_DPAD_DOWN: 550 if (!event.isAltPressed()) { 551 handled = arrowScroll(View.FOCUS_DOWN); 552 } else { 553 handled = fullScroll(View.FOCUS_DOWN); 554 } 555 break; 556 case KeyEvent.KEYCODE_SPACE: 557 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 558 break; 559 } 560 } 561 562 return handled; 563 } 564 565 private boolean inChild(int x, int y) { 566 if (getChildCount() > 0) { 567 final int scrollY = getScrollY(); 568 final View child = getChildAt(0); 569 return !(y < child.getTop() - scrollY 570 || y >= child.getBottom() - scrollY 571 || x < child.getLeft() 572 || x >= child.getRight()); 573 } 574 return false; 575 } 576 577 private void initOrResetVelocityTracker() { 578 if (mVelocityTracker == null) { 579 mVelocityTracker = VelocityTracker.obtain(); 580 } else { 581 mVelocityTracker.clear(); 582 } 583 } 584 585 private void initVelocityTrackerIfNotExists() { 586 if (mVelocityTracker == null) { 587 mVelocityTracker = VelocityTracker.obtain(); 588 } 589 } 590 591 private void recycleVelocityTracker() { 592 if (mVelocityTracker != null) { 593 mVelocityTracker.recycle(); 594 mVelocityTracker = null; 595 } 596 } 597 598 @Override 599 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 600 if (disallowIntercept) { 601 recycleVelocityTracker(); 602 } 603 super.requestDisallowInterceptTouchEvent(disallowIntercept); 604 } 605 606 607 @Override 608 public boolean onInterceptTouchEvent(MotionEvent ev) { 609 /* 610 * This method JUST determines whether we want to intercept the motion. 611 * If we return true, onMotionEvent will be called and we do the actual 612 * scrolling there. 613 */ 614 615 /* 616 * Shortcut the most recurring case: the user is in the dragging 617 * state and he is moving his finger. We want to intercept this 618 * motion. 619 */ 620 final int action = ev.getAction(); 621 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 622 return true; 623 } 624 625 switch (action & MotionEvent.ACTION_MASK) { 626 case MotionEvent.ACTION_MOVE: { 627 /* 628 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 629 * whether the user has moved far enough from his original down touch. 630 */ 631 632 /* 633 * Locally do absolute value. mLastMotionY is set to the y value 634 * of the down event. 635 */ 636 final int activePointerId = mActivePointerId; 637 if (activePointerId == INVALID_POINTER) { 638 // If we don't have a valid id, the touch down wasn't on content. 639 break; 640 } 641 642 final int pointerIndex = ev.findPointerIndex(activePointerId); 643 if (pointerIndex == -1) { 644 Log.e(TAG, "Invalid pointerId=" + activePointerId 645 + " in onInterceptTouchEvent"); 646 break; 647 } 648 649 final int y = (int) ev.getY(pointerIndex); 650 final int yDiff = Math.abs(y - mLastMotionY); 651 if (yDiff > mTouchSlop 652 && (getNestedScrollAxes() & ViewCompat.SCROLL_AXIS_VERTICAL) == 0) { 653 mIsBeingDragged = true; 654 mLastMotionY = y; 655 initVelocityTrackerIfNotExists(); 656 mVelocityTracker.addMovement(ev); 657 mNestedYOffset = 0; 658 final ViewParent parent = getParent(); 659 if (parent != null) { 660 parent.requestDisallowInterceptTouchEvent(true); 661 } 662 } 663 break; 664 } 665 666 case MotionEvent.ACTION_DOWN: { 667 final int y = (int) ev.getY(); 668 if (!inChild((int) ev.getX(), (int) y)) { 669 mIsBeingDragged = false; 670 recycleVelocityTracker(); 671 break; 672 } 673 674 /* 675 * Remember location of down touch. 676 * ACTION_DOWN always refers to pointer index 0. 677 */ 678 mLastMotionY = y; 679 mActivePointerId = ev.getPointerId(0); 680 681 initOrResetVelocityTracker(); 682 mVelocityTracker.addMovement(ev); 683 /* 684 * If being flinged and user touches the screen, initiate drag; 685 * otherwise don't. mScroller.isFinished should be false when 686 * being flinged. We need to call computeScrollOffset() first so that 687 * isFinished() is correct. 688 */ 689 mScroller.computeScrollOffset(); 690 mIsBeingDragged = !mScroller.isFinished(); 691 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 692 break; 693 } 694 695 case MotionEvent.ACTION_CANCEL: 696 case MotionEvent.ACTION_UP: 697 /* Release the drag */ 698 mIsBeingDragged = false; 699 mActivePointerId = INVALID_POINTER; 700 recycleVelocityTracker(); 701 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { 702 ViewCompat.postInvalidateOnAnimation(this); 703 } 704 stopNestedScroll(); 705 break; 706 case MotionEvent.ACTION_POINTER_UP: 707 onSecondaryPointerUp(ev); 708 break; 709 } 710 711 /* 712 * The only time we want to intercept motion events is if we are in the 713 * drag mode. 714 */ 715 return mIsBeingDragged; 716 } 717 718 @Override 719 public boolean onTouchEvent(MotionEvent ev) { 720 initVelocityTrackerIfNotExists(); 721 722 MotionEvent vtev = MotionEvent.obtain(ev); 723 724 final int actionMasked = ev.getActionMasked(); 725 726 if (actionMasked == MotionEvent.ACTION_DOWN) { 727 mNestedYOffset = 0; 728 } 729 vtev.offsetLocation(0, mNestedYOffset); 730 731 switch (actionMasked) { 732 case MotionEvent.ACTION_DOWN: { 733 if (getChildCount() == 0) { 734 return false; 735 } 736 if ((mIsBeingDragged = !mScroller.isFinished())) { 737 final ViewParent parent = getParent(); 738 if (parent != null) { 739 parent.requestDisallowInterceptTouchEvent(true); 740 } 741 } 742 743 /* 744 * If being flinged and user touches, stop the fling. isFinished 745 * will be false if being flinged. 746 */ 747 if (!mScroller.isFinished()) { 748 mScroller.abortAnimation(); 749 } 750 751 // Remember where the motion event started 752 mLastMotionY = (int) ev.getY(); 753 mActivePointerId = ev.getPointerId(0); 754 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 755 break; 756 } 757 case MotionEvent.ACTION_MOVE: 758 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 759 if (activePointerIndex == -1) { 760 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 761 break; 762 } 763 764 final int y = (int) ev.getY(activePointerIndex); 765 int deltaY = mLastMotionY - y; 766 if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) { 767 deltaY -= mScrollConsumed[1]; 768 vtev.offsetLocation(0, mScrollOffset[1]); 769 mNestedYOffset += mScrollOffset[1]; 770 } 771 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 772 final ViewParent parent = getParent(); 773 if (parent != null) { 774 parent.requestDisallowInterceptTouchEvent(true); 775 } 776 mIsBeingDragged = true; 777 if (deltaY > 0) { 778 deltaY -= mTouchSlop; 779 } else { 780 deltaY += mTouchSlop; 781 } 782 } 783 if (mIsBeingDragged) { 784 // Scroll to follow the motion event 785 mLastMotionY = y - mScrollOffset[1]; 786 787 final int oldY = getScrollY(); 788 final int range = getScrollRange(); 789 final int overscrollMode = getOverScrollMode(); 790 boolean canOverscroll = overscrollMode == View.OVER_SCROLL_ALWAYS 791 || (overscrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 792 793 // Calling overScrollByCompat will call onOverScrolled, which 794 // calls onScrollChanged if applicable. 795 if (overScrollByCompat(0, deltaY, 0, getScrollY(), 0, range, 0, 796 0, true) && !hasNestedScrollingParent()) { 797 // Break our velocity if we hit a scroll barrier. 798 mVelocityTracker.clear(); 799 } 800 801 final int scrolledDeltaY = getScrollY() - oldY; 802 final int unconsumedY = deltaY - scrolledDeltaY; 803 if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) { 804 mLastMotionY -= mScrollOffset[1]; 805 vtev.offsetLocation(0, mScrollOffset[1]); 806 mNestedYOffset += mScrollOffset[1]; 807 } else if (canOverscroll) { 808 ensureGlows(); 809 final int pulledToY = oldY + deltaY; 810 if (pulledToY < 0) { 811 mEdgeGlowTop.onPull((float) deltaY / getHeight(), 812 ev.getX(activePointerIndex) / getWidth()); 813 if (!mEdgeGlowBottom.isFinished()) { 814 mEdgeGlowBottom.onRelease(); 815 } 816 } else if (pulledToY > range) { 817 mEdgeGlowBottom.onPull((float) deltaY / getHeight(), 818 1.f - ev.getX(activePointerIndex) 819 / getWidth()); 820 if (!mEdgeGlowTop.isFinished()) { 821 mEdgeGlowTop.onRelease(); 822 } 823 } 824 if (mEdgeGlowTop != null 825 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 826 ViewCompat.postInvalidateOnAnimation(this); 827 } 828 } 829 } 830 break; 831 case MotionEvent.ACTION_UP: 832 if (mIsBeingDragged) { 833 final VelocityTracker velocityTracker = mVelocityTracker; 834 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 835 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 836 837 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 838 flingWithNestedDispatch(-initialVelocity); 839 } else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 840 getScrollRange())) { 841 ViewCompat.postInvalidateOnAnimation(this); 842 } 843 } 844 mActivePointerId = INVALID_POINTER; 845 endDrag(); 846 break; 847 case MotionEvent.ACTION_CANCEL: 848 if (mIsBeingDragged && getChildCount() > 0) { 849 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 850 getScrollRange())) { 851 ViewCompat.postInvalidateOnAnimation(this); 852 } 853 } 854 mActivePointerId = INVALID_POINTER; 855 endDrag(); 856 break; 857 case MotionEvent.ACTION_POINTER_DOWN: { 858 final int index = ev.getActionIndex(); 859 mLastMotionY = (int) ev.getY(index); 860 mActivePointerId = ev.getPointerId(index); 861 break; 862 } 863 case MotionEvent.ACTION_POINTER_UP: 864 onSecondaryPointerUp(ev); 865 mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId)); 866 break; 867 } 868 869 if (mVelocityTracker != null) { 870 mVelocityTracker.addMovement(vtev); 871 } 872 vtev.recycle(); 873 return true; 874 } 875 876 private void onSecondaryPointerUp(MotionEvent ev) { 877 final int pointerIndex = ev.getActionIndex(); 878 final int pointerId = ev.getPointerId(pointerIndex); 879 if (pointerId == mActivePointerId) { 880 // This was our active pointer going up. Choose a new 881 // active pointer and adjust accordingly. 882 // TODO: Make this decision more intelligent. 883 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 884 mLastMotionY = (int) ev.getY(newPointerIndex); 885 mActivePointerId = ev.getPointerId(newPointerIndex); 886 if (mVelocityTracker != null) { 887 mVelocityTracker.clear(); 888 } 889 } 890 } 891 892 public boolean onGenericMotionEvent(MotionEvent event) { 893 if ((event.getSource() & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) { 894 switch (event.getAction()) { 895 case MotionEvent.ACTION_SCROLL: { 896 if (!mIsBeingDragged) { 897 final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); 898 if (vscroll != 0) { 899 final int delta = (int) (vscroll * getVerticalScrollFactorCompat()); 900 final int range = getScrollRange(); 901 int oldScrollY = getScrollY(); 902 int newScrollY = oldScrollY - delta; 903 if (newScrollY < 0) { 904 newScrollY = 0; 905 } else if (newScrollY > range) { 906 newScrollY = range; 907 } 908 if (newScrollY != oldScrollY) { 909 super.scrollTo(getScrollX(), newScrollY); 910 return true; 911 } 912 } 913 } 914 } 915 } 916 } 917 return false; 918 } 919 920 private float getVerticalScrollFactorCompat() { 921 if (mVerticalScrollFactor == 0) { 922 TypedValue outValue = new TypedValue(); 923 final Context context = getContext(); 924 if (!context.getTheme().resolveAttribute( 925 android.R.attr.listPreferredItemHeight, outValue, true)) { 926 throw new IllegalStateException( 927 "Expected theme to define listPreferredItemHeight."); 928 } 929 mVerticalScrollFactor = outValue.getDimension( 930 context.getResources().getDisplayMetrics()); 931 } 932 return mVerticalScrollFactor; 933 } 934 935 @Override 936 protected void onOverScrolled(int scrollX, int scrollY, 937 boolean clampedX, boolean clampedY) { 938 super.scrollTo(scrollX, scrollY); 939 } 940 941 boolean overScrollByCompat(int deltaX, int deltaY, 942 int scrollX, int scrollY, 943 int scrollRangeX, int scrollRangeY, 944 int maxOverScrollX, int maxOverScrollY, 945 boolean isTouchEvent) { 946 final int overScrollMode = getOverScrollMode(); 947 final boolean canScrollHorizontal = 948 computeHorizontalScrollRange() > computeHorizontalScrollExtent(); 949 final boolean canScrollVertical = 950 computeVerticalScrollRange() > computeVerticalScrollExtent(); 951 final boolean overScrollHorizontal = overScrollMode == View.OVER_SCROLL_ALWAYS 952 || (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal); 953 final boolean overScrollVertical = overScrollMode == View.OVER_SCROLL_ALWAYS 954 || (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical); 955 956 int newScrollX = scrollX + deltaX; 957 if (!overScrollHorizontal) { 958 maxOverScrollX = 0; 959 } 960 961 int newScrollY = scrollY + deltaY; 962 if (!overScrollVertical) { 963 maxOverScrollY = 0; 964 } 965 966 // Clamp values if at the limits and record 967 final int left = -maxOverScrollX; 968 final int right = maxOverScrollX + scrollRangeX; 969 final int top = -maxOverScrollY; 970 final int bottom = maxOverScrollY + scrollRangeY; 971 972 boolean clampedX = false; 973 if (newScrollX > right) { 974 newScrollX = right; 975 clampedX = true; 976 } else if (newScrollX < left) { 977 newScrollX = left; 978 clampedX = true; 979 } 980 981 boolean clampedY = false; 982 if (newScrollY > bottom) { 983 newScrollY = bottom; 984 clampedY = true; 985 } else if (newScrollY < top) { 986 newScrollY = top; 987 clampedY = true; 988 } 989 990 if (clampedY) { 991 mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange()); 992 } 993 994 onOverScrolled(newScrollX, newScrollY, clampedX, clampedY); 995 996 return clampedX || clampedY; 997 } 998 999 int getScrollRange() { 1000 int scrollRange = 0; 1001 if (getChildCount() > 0) { 1002 View child = getChildAt(0); 1003 scrollRange = Math.max(0, 1004 child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop())); 1005 } 1006 return scrollRange; 1007 } 1008 1009 /** 1010 * <p> 1011 * Finds the next focusable component that fits in the specified bounds. 1012 * </p> 1013 * 1014 * @param topFocus look for a candidate is the one at the top of the bounds 1015 * if topFocus is true, or at the bottom of the bounds if topFocus is 1016 * false 1017 * @param top the top offset of the bounds in which a focusable must be 1018 * found 1019 * @param bottom the bottom offset of the bounds in which a focusable must 1020 * be found 1021 * @return the next focusable component in the bounds or null if none can 1022 * be found 1023 */ 1024 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 1025 1026 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 1027 View focusCandidate = null; 1028 1029 /* 1030 * A fully contained focusable is one where its top is below the bound's 1031 * top, and its bottom is above the bound's bottom. A partially 1032 * contained focusable is one where some part of it is within the 1033 * bounds, but it also has some part that is not within bounds. A fully contained 1034 * focusable is preferred to a partially contained focusable. 1035 */ 1036 boolean foundFullyContainedFocusable = false; 1037 1038 int count = focusables.size(); 1039 for (int i = 0; i < count; i++) { 1040 View view = focusables.get(i); 1041 int viewTop = view.getTop(); 1042 int viewBottom = view.getBottom(); 1043 1044 if (top < viewBottom && viewTop < bottom) { 1045 /* 1046 * the focusable is in the target area, it is a candidate for 1047 * focusing 1048 */ 1049 1050 final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom); 1051 1052 if (focusCandidate == null) { 1053 /* No candidate, take this one */ 1054 focusCandidate = view; 1055 foundFullyContainedFocusable = viewIsFullyContained; 1056 } else { 1057 final boolean viewIsCloserToBoundary = 1058 (topFocus && viewTop < focusCandidate.getTop()) 1059 || (!topFocus && viewBottom > focusCandidate.getBottom()); 1060 1061 if (foundFullyContainedFocusable) { 1062 if (viewIsFullyContained && viewIsCloserToBoundary) { 1063 /* 1064 * We're dealing with only fully contained views, so 1065 * it has to be closer to the boundary to beat our 1066 * candidate 1067 */ 1068 focusCandidate = view; 1069 } 1070 } else { 1071 if (viewIsFullyContained) { 1072 /* Any fully contained view beats a partially contained view */ 1073 focusCandidate = view; 1074 foundFullyContainedFocusable = true; 1075 } else if (viewIsCloserToBoundary) { 1076 /* 1077 * Partially contained view beats another partially 1078 * contained view if it's closer 1079 */ 1080 focusCandidate = view; 1081 } 1082 } 1083 } 1084 } 1085 } 1086 1087 return focusCandidate; 1088 } 1089 1090 /** 1091 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 1092 * method will scroll the view by one page up or down and give the focus 1093 * to the topmost/bottommost component in the new visible area. If no 1094 * component is a good candidate for focus, this scrollview reclaims the 1095 * focus.</p> 1096 * 1097 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1098 * to go one page up or 1099 * {@link android.view.View#FOCUS_DOWN} to go one page down 1100 * @return true if the key event is consumed by this method, false otherwise 1101 */ 1102 public boolean pageScroll(int direction) { 1103 boolean down = direction == View.FOCUS_DOWN; 1104 int height = getHeight(); 1105 1106 if (down) { 1107 mTempRect.top = getScrollY() + height; 1108 int count = getChildCount(); 1109 if (count > 0) { 1110 View view = getChildAt(count - 1); 1111 if (mTempRect.top + height > view.getBottom()) { 1112 mTempRect.top = view.getBottom() - height; 1113 } 1114 } 1115 } else { 1116 mTempRect.top = getScrollY() - height; 1117 if (mTempRect.top < 0) { 1118 mTempRect.top = 0; 1119 } 1120 } 1121 mTempRect.bottom = mTempRect.top + height; 1122 1123 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1124 } 1125 1126 /** 1127 * <p>Handles scrolling in response to a "home/end" shortcut press. This 1128 * method will scroll the view to the top or bottom and give the focus 1129 * to the topmost/bottommost component in the new visible area. If no 1130 * component is a good candidate for focus, this scrollview reclaims the 1131 * focus.</p> 1132 * 1133 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1134 * to go the top of the view or 1135 * {@link android.view.View#FOCUS_DOWN} to go the bottom 1136 * @return true if the key event is consumed by this method, false otherwise 1137 */ 1138 public boolean fullScroll(int direction) { 1139 boolean down = direction == View.FOCUS_DOWN; 1140 int height = getHeight(); 1141 1142 mTempRect.top = 0; 1143 mTempRect.bottom = height; 1144 1145 if (down) { 1146 int count = getChildCount(); 1147 if (count > 0) { 1148 View view = getChildAt(count - 1); 1149 mTempRect.bottom = view.getBottom() + getPaddingBottom(); 1150 mTempRect.top = mTempRect.bottom - height; 1151 } 1152 } 1153 1154 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1155 } 1156 1157 /** 1158 * <p>Scrolls the view to make the area defined by <code>top</code> and 1159 * <code>bottom</code> visible. This method attempts to give the focus 1160 * to a component visible in this area. If no component can be focused in 1161 * the new visible area, the focus is reclaimed by this ScrollView.</p> 1162 * 1163 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1164 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 1165 * @param top the top offset of the new area to be made visible 1166 * @param bottom the bottom offset of the new area to be made visible 1167 * @return true if the key event is consumed by this method, false otherwise 1168 */ 1169 private boolean scrollAndFocus(int direction, int top, int bottom) { 1170 boolean handled = true; 1171 1172 int height = getHeight(); 1173 int containerTop = getScrollY(); 1174 int containerBottom = containerTop + height; 1175 boolean up = direction == View.FOCUS_UP; 1176 1177 View newFocused = findFocusableViewInBounds(up, top, bottom); 1178 if (newFocused == null) { 1179 newFocused = this; 1180 } 1181 1182 if (top >= containerTop && bottom <= containerBottom) { 1183 handled = false; 1184 } else { 1185 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1186 doScrollY(delta); 1187 } 1188 1189 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1190 1191 return handled; 1192 } 1193 1194 /** 1195 * Handle scrolling in response to an up or down arrow click. 1196 * 1197 * @param direction The direction corresponding to the arrow key that was 1198 * pressed 1199 * @return True if we consumed the event, false otherwise 1200 */ 1201 public boolean arrowScroll(int direction) { 1202 1203 View currentFocused = findFocus(); 1204 if (currentFocused == this) currentFocused = null; 1205 1206 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1207 1208 final int maxJump = getMaxScrollAmount(); 1209 1210 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1211 nextFocused.getDrawingRect(mTempRect); 1212 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1213 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1214 doScrollY(scrollDelta); 1215 nextFocused.requestFocus(direction); 1216 } else { 1217 // no new focus 1218 int scrollDelta = maxJump; 1219 1220 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1221 scrollDelta = getScrollY(); 1222 } else if (direction == View.FOCUS_DOWN) { 1223 if (getChildCount() > 0) { 1224 int daBottom = getChildAt(0).getBottom(); 1225 int screenBottom = getScrollY() + getHeight() - getPaddingBottom(); 1226 if (daBottom - screenBottom < maxJump) { 1227 scrollDelta = daBottom - screenBottom; 1228 } 1229 } 1230 } 1231 if (scrollDelta == 0) { 1232 return false; 1233 } 1234 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1235 } 1236 1237 if (currentFocused != null && currentFocused.isFocused() 1238 && isOffScreen(currentFocused)) { 1239 // previously focused item still has focus and is off screen, give 1240 // it up (take it back to ourselves) 1241 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1242 // sure to 1243 // get it) 1244 final int descendantFocusability = getDescendantFocusability(); // save 1245 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1246 requestFocus(); 1247 setDescendantFocusability(descendantFocusability); // restore 1248 } 1249 return true; 1250 } 1251 1252 /** 1253 * @return whether the descendant of this scroll view is scrolled off 1254 * screen. 1255 */ 1256 private boolean isOffScreen(View descendant) { 1257 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1258 } 1259 1260 /** 1261 * @return whether the descendant of this scroll view is within delta 1262 * pixels of being on the screen. 1263 */ 1264 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1265 descendant.getDrawingRect(mTempRect); 1266 offsetDescendantRectToMyCoords(descendant, mTempRect); 1267 1268 return (mTempRect.bottom + delta) >= getScrollY() 1269 && (mTempRect.top - delta) <= (getScrollY() + height); 1270 } 1271 1272 /** 1273 * Smooth scroll by a Y delta 1274 * 1275 * @param delta the number of pixels to scroll by on the Y axis 1276 */ 1277 private void doScrollY(int delta) { 1278 if (delta != 0) { 1279 if (mSmoothScrollingEnabled) { 1280 smoothScrollBy(0, delta); 1281 } else { 1282 scrollBy(0, delta); 1283 } 1284 } 1285 } 1286 1287 /** 1288 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1289 * 1290 * @param dx the number of pixels to scroll by on the X axis 1291 * @param dy the number of pixels to scroll by on the Y axis 1292 */ 1293 public final void smoothScrollBy(int dx, int dy) { 1294 if (getChildCount() == 0) { 1295 // Nothing to do. 1296 return; 1297 } 1298 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1299 if (duration > ANIMATED_SCROLL_GAP) { 1300 final int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1301 final int bottom = getChildAt(0).getHeight(); 1302 final int maxY = Math.max(0, bottom - height); 1303 final int scrollY = getScrollY(); 1304 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1305 1306 mScroller.startScroll(getScrollX(), scrollY, 0, dy); 1307 ViewCompat.postInvalidateOnAnimation(this); 1308 } else { 1309 if (!mScroller.isFinished()) { 1310 mScroller.abortAnimation(); 1311 } 1312 scrollBy(dx, dy); 1313 } 1314 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1315 } 1316 1317 /** 1318 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1319 * 1320 * @param x the position where to scroll on the X axis 1321 * @param y the position where to scroll on the Y axis 1322 */ 1323 public final void smoothScrollTo(int x, int y) { 1324 smoothScrollBy(x - getScrollX(), y - getScrollY()); 1325 } 1326 1327 /** 1328 * <p>The scroll range of a scroll view is the overall height of all of its 1329 * children.</p> 1330 * @hide 1331 */ 1332 @RestrictTo(LIBRARY_GROUP) 1333 @Override 1334 public int computeVerticalScrollRange() { 1335 final int count = getChildCount(); 1336 final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop(); 1337 if (count == 0) { 1338 return contentHeight; 1339 } 1340 1341 int scrollRange = getChildAt(0).getBottom(); 1342 final int scrollY = getScrollY(); 1343 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1344 if (scrollY < 0) { 1345 scrollRange -= scrollY; 1346 } else if (scrollY > overscrollBottom) { 1347 scrollRange += scrollY - overscrollBottom; 1348 } 1349 1350 return scrollRange; 1351 } 1352 1353 /** @hide */ 1354 @RestrictTo(LIBRARY_GROUP) 1355 @Override 1356 public int computeVerticalScrollOffset() { 1357 return Math.max(0, super.computeVerticalScrollOffset()); 1358 } 1359 1360 /** @hide */ 1361 @RestrictTo(LIBRARY_GROUP) 1362 @Override 1363 public int computeVerticalScrollExtent() { 1364 return super.computeVerticalScrollExtent(); 1365 } 1366 1367 /** @hide */ 1368 @RestrictTo(LIBRARY_GROUP) 1369 @Override 1370 public int computeHorizontalScrollRange() { 1371 return super.computeHorizontalScrollRange(); 1372 } 1373 1374 /** @hide */ 1375 @RestrictTo(LIBRARY_GROUP) 1376 @Override 1377 public int computeHorizontalScrollOffset() { 1378 return super.computeHorizontalScrollOffset(); 1379 } 1380 1381 /** @hide */ 1382 @RestrictTo(LIBRARY_GROUP) 1383 @Override 1384 public int computeHorizontalScrollExtent() { 1385 return super.computeHorizontalScrollExtent(); 1386 } 1387 1388 @Override 1389 protected void measureChild(View child, int parentWidthMeasureSpec, 1390 int parentHeightMeasureSpec) { 1391 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1392 1393 int childWidthMeasureSpec; 1394 int childHeightMeasureSpec; 1395 1396 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() 1397 + getPaddingRight(), lp.width); 1398 1399 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1400 1401 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1402 } 1403 1404 @Override 1405 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1406 int parentHeightMeasureSpec, int heightUsed) { 1407 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1408 1409 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1410 getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin 1411 + widthUsed, lp.width); 1412 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1413 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1414 1415 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1416 } 1417 1418 @Override 1419 public void computeScroll() { 1420 if (mScroller.computeScrollOffset()) { 1421 int oldX = getScrollX(); 1422 int oldY = getScrollY(); 1423 int x = mScroller.getCurrX(); 1424 int y = mScroller.getCurrY(); 1425 1426 if (oldX != x || oldY != y) { 1427 final int range = getScrollRange(); 1428 final int overscrollMode = getOverScrollMode(); 1429 final boolean canOverscroll = overscrollMode == View.OVER_SCROLL_ALWAYS 1430 || (overscrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1431 1432 overScrollByCompat(x - oldX, y - oldY, oldX, oldY, 0, range, 1433 0, 0, false); 1434 1435 if (canOverscroll) { 1436 ensureGlows(); 1437 if (y <= 0 && oldY > 0) { 1438 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1439 } else if (y >= range && oldY < range) { 1440 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1441 } 1442 } 1443 } 1444 } 1445 } 1446 1447 /** 1448 * Scrolls the view to the given child. 1449 * 1450 * @param child the View to scroll to 1451 */ 1452 private void scrollToChild(View child) { 1453 child.getDrawingRect(mTempRect); 1454 1455 /* Offset from child's local coordinates to ScrollView coordinates */ 1456 offsetDescendantRectToMyCoords(child, mTempRect); 1457 1458 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1459 1460 if (scrollDelta != 0) { 1461 scrollBy(0, scrollDelta); 1462 } 1463 } 1464 1465 /** 1466 * If rect is off screen, scroll just enough to get it (or at least the 1467 * first screen size chunk of it) on screen. 1468 * 1469 * @param rect The rectangle. 1470 * @param immediate True to scroll immediately without animation 1471 * @return true if scrolling was performed 1472 */ 1473 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1474 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1475 final boolean scroll = delta != 0; 1476 if (scroll) { 1477 if (immediate) { 1478 scrollBy(0, delta); 1479 } else { 1480 smoothScrollBy(0, delta); 1481 } 1482 } 1483 return scroll; 1484 } 1485 1486 /** 1487 * Compute the amount to scroll in the Y direction in order to get 1488 * a rectangle completely on the screen (or, if taller than the screen, 1489 * at least the first screen size chunk of it). 1490 * 1491 * @param rect The rect. 1492 * @return The scroll delta. 1493 */ 1494 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1495 if (getChildCount() == 0) return 0; 1496 1497 int height = getHeight(); 1498 int screenTop = getScrollY(); 1499 int screenBottom = screenTop + height; 1500 1501 int fadingEdge = getVerticalFadingEdgeLength(); 1502 1503 // leave room for top fading edge as long as rect isn't at very top 1504 if (rect.top > 0) { 1505 screenTop += fadingEdge; 1506 } 1507 1508 // leave room for bottom fading edge as long as rect isn't at very bottom 1509 if (rect.bottom < getChildAt(0).getHeight()) { 1510 screenBottom -= fadingEdge; 1511 } 1512 1513 int scrollYDelta = 0; 1514 1515 if (rect.bottom > screenBottom && rect.top > screenTop) { 1516 // need to move down to get it in view: move down just enough so 1517 // that the entire rectangle is in view (or at least the first 1518 // screen size chunk). 1519 1520 if (rect.height() > height) { 1521 // just enough to get screen size chunk on 1522 scrollYDelta += (rect.top - screenTop); 1523 } else { 1524 // get entire rect at bottom of screen 1525 scrollYDelta += (rect.bottom - screenBottom); 1526 } 1527 1528 // make sure we aren't scrolling beyond the end of our content 1529 int bottom = getChildAt(0).getBottom(); 1530 int distanceToBottom = bottom - screenBottom; 1531 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1532 1533 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1534 // need to move up to get it in view: move up just enough so that 1535 // entire rectangle is in view (or at least the first screen 1536 // size chunk of it). 1537 1538 if (rect.height() > height) { 1539 // screen size chunk 1540 scrollYDelta -= (screenBottom - rect.bottom); 1541 } else { 1542 // entire rect at top 1543 scrollYDelta -= (screenTop - rect.top); 1544 } 1545 1546 // make sure we aren't scrolling any further than the top our content 1547 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1548 } 1549 return scrollYDelta; 1550 } 1551 1552 @Override 1553 public void requestChildFocus(View child, View focused) { 1554 if (!mIsLayoutDirty) { 1555 scrollToChild(focused); 1556 } else { 1557 // The child may not be laid out yet, we can't compute the scroll yet 1558 mChildToScrollTo = focused; 1559 } 1560 super.requestChildFocus(child, focused); 1561 } 1562 1563 1564 /** 1565 * When looking for focus in children of a scroll view, need to be a little 1566 * more careful not to give focus to something that is scrolled off screen. 1567 * 1568 * This is more expensive than the default {@link android.view.ViewGroup} 1569 * implementation, otherwise this behavior might have been made the default. 1570 */ 1571 @Override 1572 protected boolean onRequestFocusInDescendants(int direction, 1573 Rect previouslyFocusedRect) { 1574 1575 // convert from forward / backward notation to up / down / left / right 1576 // (ugh). 1577 if (direction == View.FOCUS_FORWARD) { 1578 direction = View.FOCUS_DOWN; 1579 } else if (direction == View.FOCUS_BACKWARD) { 1580 direction = View.FOCUS_UP; 1581 } 1582 1583 final View nextFocus = previouslyFocusedRect == null 1584 ? FocusFinder.getInstance().findNextFocus(this, null, direction) 1585 : FocusFinder.getInstance().findNextFocusFromRect( 1586 this, previouslyFocusedRect, direction); 1587 1588 if (nextFocus == null) { 1589 return false; 1590 } 1591 1592 if (isOffScreen(nextFocus)) { 1593 return false; 1594 } 1595 1596 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1597 } 1598 1599 @Override 1600 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1601 boolean immediate) { 1602 // offset into coordinate space of this scroll view 1603 rectangle.offset(child.getLeft() - child.getScrollX(), 1604 child.getTop() - child.getScrollY()); 1605 1606 return scrollToChildRect(rectangle, immediate); 1607 } 1608 1609 @Override 1610 public void requestLayout() { 1611 mIsLayoutDirty = true; 1612 super.requestLayout(); 1613 } 1614 1615 @Override 1616 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1617 super.onLayout(changed, l, t, r, b); 1618 mIsLayoutDirty = false; 1619 // Give a child focus if it needs it 1620 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1621 scrollToChild(mChildToScrollTo); 1622 } 1623 mChildToScrollTo = null; 1624 1625 if (!mIsLaidOut) { 1626 if (mSavedState != null) { 1627 scrollTo(getScrollX(), mSavedState.scrollPosition); 1628 mSavedState = null; 1629 } // mScrollY default value is "0" 1630 1631 final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; 1632 final int scrollRange = Math.max(0, 1633 childHeight - (b - t - getPaddingBottom() - getPaddingTop())); 1634 1635 // Don't forget to clamp 1636 if (getScrollY() > scrollRange) { 1637 scrollTo(getScrollX(), scrollRange); 1638 } else if (getScrollY() < 0) { 1639 scrollTo(getScrollX(), 0); 1640 } 1641 } 1642 1643 // Calling this with the present values causes it to re-claim them 1644 scrollTo(getScrollX(), getScrollY()); 1645 mIsLaidOut = true; 1646 } 1647 1648 @Override 1649 public void onAttachedToWindow() { 1650 super.onAttachedToWindow(); 1651 1652 mIsLaidOut = false; 1653 } 1654 1655 @Override 1656 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1657 super.onSizeChanged(w, h, oldw, oldh); 1658 1659 View currentFocused = findFocus(); 1660 if (null == currentFocused || this == currentFocused) { 1661 return; 1662 } 1663 1664 // If the currently-focused view was visible on the screen when the 1665 // screen was at the old height, then scroll the screen to make that 1666 // view visible with the new screen height. 1667 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1668 currentFocused.getDrawingRect(mTempRect); 1669 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1670 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1671 doScrollY(scrollDelta); 1672 } 1673 } 1674 1675 /** 1676 * Return true if child is a descendant of parent, (or equal to the parent). 1677 */ 1678 private static boolean isViewDescendantOf(View child, View parent) { 1679 if (child == parent) { 1680 return true; 1681 } 1682 1683 final ViewParent theParent = child.getParent(); 1684 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1685 } 1686 1687 /** 1688 * Fling the scroll view 1689 * 1690 * @param velocityY The initial velocity in the Y direction. Positive 1691 * numbers mean that the finger/cursor is moving down the screen, 1692 * which means we want to scroll towards the top. 1693 */ 1694 public void fling(int velocityY) { 1695 if (getChildCount() > 0) { 1696 int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1697 int bottom = getChildAt(0).getHeight(); 1698 1699 mScroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0, 1700 Math.max(0, bottom - height), 0, height / 2); 1701 1702 ViewCompat.postInvalidateOnAnimation(this); 1703 } 1704 } 1705 1706 private void flingWithNestedDispatch(int velocityY) { 1707 final int scrollY = getScrollY(); 1708 final boolean canFling = (scrollY > 0 || velocityY > 0) 1709 && (scrollY < getScrollRange() || velocityY < 0); 1710 if (!dispatchNestedPreFling(0, velocityY)) { 1711 dispatchNestedFling(0, velocityY, canFling); 1712 if (canFling) { 1713 fling(velocityY); 1714 } 1715 } 1716 } 1717 1718 private void endDrag() { 1719 mIsBeingDragged = false; 1720 1721 recycleVelocityTracker(); 1722 stopNestedScroll(); 1723 1724 if (mEdgeGlowTop != null) { 1725 mEdgeGlowTop.onRelease(); 1726 mEdgeGlowBottom.onRelease(); 1727 } 1728 } 1729 1730 /** 1731 * {@inheritDoc} 1732 * 1733 * <p>This version also clamps the scrolling to the bounds of our child. 1734 */ 1735 @Override 1736 public void scrollTo(int x, int y) { 1737 // we rely on the fact the View.scrollBy calls scrollTo. 1738 if (getChildCount() > 0) { 1739 View child = getChildAt(0); 1740 x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); 1741 y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); 1742 if (x != getScrollX() || y != getScrollY()) { 1743 super.scrollTo(x, y); 1744 } 1745 } 1746 } 1747 1748 private void ensureGlows() { 1749 if (getOverScrollMode() != View.OVER_SCROLL_NEVER) { 1750 if (mEdgeGlowTop == null) { 1751 Context context = getContext(); 1752 mEdgeGlowTop = new EdgeEffectCompat(context); 1753 mEdgeGlowBottom = new EdgeEffectCompat(context); 1754 } 1755 } else { 1756 mEdgeGlowTop = null; 1757 mEdgeGlowBottom = null; 1758 } 1759 } 1760 1761 @Override 1762 public void draw(Canvas canvas) { 1763 super.draw(canvas); 1764 if (mEdgeGlowTop != null) { 1765 final int scrollY = getScrollY(); 1766 if (!mEdgeGlowTop.isFinished()) { 1767 final int restoreCount = canvas.save(); 1768 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1769 1770 canvas.translate(getPaddingLeft(), Math.min(0, scrollY)); 1771 mEdgeGlowTop.setSize(width, getHeight()); 1772 if (mEdgeGlowTop.draw(canvas)) { 1773 ViewCompat.postInvalidateOnAnimation(this); 1774 } 1775 canvas.restoreToCount(restoreCount); 1776 } 1777 if (!mEdgeGlowBottom.isFinished()) { 1778 final int restoreCount = canvas.save(); 1779 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1780 final int height = getHeight(); 1781 1782 canvas.translate(-width + getPaddingLeft(), 1783 Math.max(getScrollRange(), scrollY) + height); 1784 canvas.rotate(180, width, 0); 1785 mEdgeGlowBottom.setSize(width, height); 1786 if (mEdgeGlowBottom.draw(canvas)) { 1787 ViewCompat.postInvalidateOnAnimation(this); 1788 } 1789 canvas.restoreToCount(restoreCount); 1790 } 1791 } 1792 } 1793 1794 private static int clamp(int n, int my, int child) { 1795 if (my >= child || n < 0) { 1796 /* my >= child is this case: 1797 * |--------------- me ---------------| 1798 * |------ child ------| 1799 * or 1800 * |--------------- me ---------------| 1801 * |------ child ------| 1802 * or 1803 * |--------------- me ---------------| 1804 * |------ child ------| 1805 * 1806 * n < 0 is this case: 1807 * |------ me ------| 1808 * |-------- child --------| 1809 * |-- mScrollX --| 1810 */ 1811 return 0; 1812 } 1813 if ((my + n) > child) { 1814 /* this case: 1815 * |------ me ------| 1816 * |------ child ------| 1817 * |-- mScrollX --| 1818 */ 1819 return child - my; 1820 } 1821 return n; 1822 } 1823 1824 @Override 1825 protected void onRestoreInstanceState(Parcelable state) { 1826 if (!(state instanceof SavedState)) { 1827 super.onRestoreInstanceState(state); 1828 return; 1829 } 1830 1831 SavedState ss = (SavedState) state; 1832 super.onRestoreInstanceState(ss.getSuperState()); 1833 mSavedState = ss; 1834 requestLayout(); 1835 } 1836 1837 @Override 1838 protected Parcelable onSaveInstanceState() { 1839 Parcelable superState = super.onSaveInstanceState(); 1840 SavedState ss = new SavedState(superState); 1841 ss.scrollPosition = getScrollY(); 1842 return ss; 1843 } 1844 1845 static class SavedState extends BaseSavedState { 1846 public int scrollPosition; 1847 1848 SavedState(Parcelable superState) { 1849 super(superState); 1850 } 1851 1852 SavedState(Parcel source) { 1853 super(source); 1854 scrollPosition = source.readInt(); 1855 } 1856 1857 @Override 1858 public void writeToParcel(Parcel dest, int flags) { 1859 super.writeToParcel(dest, flags); 1860 dest.writeInt(scrollPosition); 1861 } 1862 1863 @Override 1864 public String toString() { 1865 return "HorizontalScrollView.SavedState{" 1866 + Integer.toHexString(System.identityHashCode(this)) 1867 + " scrollPosition=" + scrollPosition + "}"; 1868 } 1869 1870 public static final Parcelable.Creator<SavedState> CREATOR = 1871 new Parcelable.Creator<SavedState>() { 1872 @Override 1873 public SavedState createFromParcel(Parcel in) { 1874 return new SavedState(in); 1875 } 1876 1877 @Override 1878 public SavedState[] newArray(int size) { 1879 return new SavedState[size]; 1880 } 1881 }; 1882 } 1883 1884 static class AccessibilityDelegate extends AccessibilityDelegateCompat { 1885 @Override 1886 public boolean performAccessibilityAction(View host, int action, Bundle arguments) { 1887 if (super.performAccessibilityAction(host, action, arguments)) { 1888 return true; 1889 } 1890 final NestedScrollView nsvHost = (NestedScrollView) host; 1891 if (!nsvHost.isEnabled()) { 1892 return false; 1893 } 1894 switch (action) { 1895 case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: { 1896 final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() 1897 - nsvHost.getPaddingTop(); 1898 final int targetScrollY = Math.min(nsvHost.getScrollY() + viewportHeight, 1899 nsvHost.getScrollRange()); 1900 if (targetScrollY != nsvHost.getScrollY()) { 1901 nsvHost.smoothScrollTo(0, targetScrollY); 1902 return true; 1903 } 1904 } 1905 return false; 1906 case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: { 1907 final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() 1908 - nsvHost.getPaddingTop(); 1909 final int targetScrollY = Math.max(nsvHost.getScrollY() - viewportHeight, 0); 1910 if (targetScrollY != nsvHost.getScrollY()) { 1911 nsvHost.smoothScrollTo(0, targetScrollY); 1912 return true; 1913 } 1914 } 1915 return false; 1916 } 1917 return false; 1918 } 1919 1920 @Override 1921 public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { 1922 super.onInitializeAccessibilityNodeInfo(host, info); 1923 final NestedScrollView nsvHost = (NestedScrollView) host; 1924 info.setClassName(ScrollView.class.getName()); 1925 if (nsvHost.isEnabled()) { 1926 final int scrollRange = nsvHost.getScrollRange(); 1927 if (scrollRange > 0) { 1928 info.setScrollable(true); 1929 if (nsvHost.getScrollY() > 0) { 1930 info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); 1931 } 1932 if (nsvHost.getScrollY() < scrollRange) { 1933 info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); 1934 } 1935 } 1936 } 1937 } 1938 1939 @Override 1940 public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { 1941 super.onInitializeAccessibilityEvent(host, event); 1942 final NestedScrollView nsvHost = (NestedScrollView) host; 1943 event.setClassName(ScrollView.class.getName()); 1944 final AccessibilityRecordCompat record = AccessibilityEventCompat.asRecord(event); 1945 final boolean scrollable = nsvHost.getScrollRange() > 0; 1946 record.setScrollable(scrollable); 1947 record.setScrollX(nsvHost.getScrollX()); 1948 record.setScrollY(nsvHost.getScrollY()); 1949 record.setMaxScrollX(nsvHost.getScrollX()); 1950 record.setMaxScrollY(nsvHost.getScrollRange()); 1951 } 1952 } 1953} 1954