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