NestedScrollView.java revision 00db92e217c3bc08acd09143cac8e3d3b0d0e813
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 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { 661 ViewCompat.postInvalidateOnAnimation(this); 662 } 663 stopNestedScroll(); 664 break; 665 case MotionEventCompat.ACTION_POINTER_UP: 666 onSecondaryPointerUp(ev); 667 break; 668 } 669 670 /* 671 * The only time we want to intercept motion events is if we are in the 672 * drag mode. 673 */ 674 return mIsBeingDragged; 675 } 676 677 @Override 678 public boolean onTouchEvent(MotionEvent ev) { 679 initVelocityTrackerIfNotExists(); 680 681 MotionEvent vtev = MotionEvent.obtain(ev); 682 683 final int actionMasked = MotionEventCompat.getActionMasked(ev); 684 685 if (actionMasked == MotionEvent.ACTION_DOWN) { 686 mNestedYOffset = 0; 687 } 688 vtev.offsetLocation(0, mNestedYOffset); 689 690 switch (actionMasked) { 691 case MotionEvent.ACTION_DOWN: { 692 if (getChildCount() == 0) { 693 return false; 694 } 695 if ((mIsBeingDragged = !mScroller.isFinished())) { 696 final ViewParent parent = getParent(); 697 if (parent != null) { 698 parent.requestDisallowInterceptTouchEvent(true); 699 } 700 } 701 702 /* 703 * If being flinged and user touches, stop the fling. isFinished 704 * will be false if being flinged. 705 */ 706 if (!mScroller.isFinished()) { 707 mScroller.abortAnimation(); 708 } 709 710 // Remember where the motion event started 711 mLastMotionY = (int) ev.getY(); 712 mActivePointerId = MotionEventCompat.getPointerId(ev, 0); 713 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 714 break; 715 } 716 case MotionEvent.ACTION_MOVE: 717 final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, 718 mActivePointerId); 719 if (activePointerIndex == -1) { 720 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 721 break; 722 } 723 724 final int y = (int) MotionEventCompat.getY(ev, activePointerIndex); 725 int deltaY = mLastMotionY - y; 726 if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) { 727 deltaY -= mScrollConsumed[1]; 728 vtev.offsetLocation(0, mScrollOffset[1]); 729 mNestedYOffset += mScrollOffset[1]; 730 } 731 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 732 final ViewParent parent = getParent(); 733 if (parent != null) { 734 parent.requestDisallowInterceptTouchEvent(true); 735 } 736 mIsBeingDragged = true; 737 if (deltaY > 0) { 738 deltaY -= mTouchSlop; 739 } else { 740 deltaY += mTouchSlop; 741 } 742 } 743 if (mIsBeingDragged) { 744 // Scroll to follow the motion event 745 mLastMotionY = y - mScrollOffset[1]; 746 747 final int oldY = getScrollY(); 748 final int range = getScrollRange(); 749 final int overscrollMode = ViewCompat.getOverScrollMode(this); 750 boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 751 (overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && 752 range > 0); 753 754 // Calling overScrollByCompat will call onOverScrolled, which 755 // calls onScrollChanged if applicable. 756 if (overScrollByCompat(0, deltaY, 0, getScrollY(), 0, range, 0, 757 0, true) && !hasNestedScrollingParent()) { 758 // Break our velocity if we hit a scroll barrier. 759 mVelocityTracker.clear(); 760 } 761 762 final int scrolledDeltaY = getScrollY() - oldY; 763 final int unconsumedY = deltaY - scrolledDeltaY; 764 if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) { 765 mLastMotionY -= mScrollOffset[1]; 766 vtev.offsetLocation(0, mScrollOffset[1]); 767 mNestedYOffset += mScrollOffset[1]; 768 } else if (canOverscroll) { 769 ensureGlows(); 770 final int pulledToY = oldY + deltaY; 771 if (pulledToY < 0) { 772 mEdgeGlowTop.onPull((float) deltaY / getHeight(), 773 MotionEventCompat.getX(ev, activePointerIndex) / getWidth()); 774 if (!mEdgeGlowBottom.isFinished()) { 775 mEdgeGlowBottom.onRelease(); 776 } 777 } else if (pulledToY > range) { 778 mEdgeGlowBottom.onPull((float) deltaY / getHeight(), 779 1.f - MotionEventCompat.getX(ev, activePointerIndex) 780 / getWidth()); 781 if (!mEdgeGlowTop.isFinished()) { 782 mEdgeGlowTop.onRelease(); 783 } 784 } 785 if (mEdgeGlowTop != null 786 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 787 ViewCompat.postInvalidateOnAnimation(this); 788 } 789 } 790 } 791 break; 792 case MotionEvent.ACTION_UP: 793 if (mIsBeingDragged) { 794 final VelocityTracker velocityTracker = mVelocityTracker; 795 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 796 int initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, 797 mActivePointerId); 798 799 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 800 flingWithNestedDispatch(-initialVelocity); 801 } else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 802 getScrollRange())) { 803 ViewCompat.postInvalidateOnAnimation(this); 804 } 805 806 mActivePointerId = INVALID_POINTER; 807 endDrag(); 808 } 809 break; 810 case MotionEvent.ACTION_CANCEL: 811 if (mIsBeingDragged && getChildCount() > 0) { 812 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 813 getScrollRange())) { 814 ViewCompat.postInvalidateOnAnimation(this); 815 } 816 mActivePointerId = INVALID_POINTER; 817 endDrag(); 818 } 819 break; 820 case MotionEventCompat.ACTION_POINTER_DOWN: { 821 final int index = MotionEventCompat.getActionIndex(ev); 822 mLastMotionY = (int) MotionEventCompat.getY(ev, index); 823 mActivePointerId = MotionEventCompat.getPointerId(ev, index); 824 break; 825 } 826 case MotionEventCompat.ACTION_POINTER_UP: 827 onSecondaryPointerUp(ev); 828 mLastMotionY = (int) MotionEventCompat.getY(ev, 829 MotionEventCompat.findPointerIndex(ev, mActivePointerId)); 830 break; 831 } 832 833 if (mVelocityTracker != null) { 834 mVelocityTracker.addMovement(vtev); 835 } 836 vtev.recycle(); 837 return true; 838 } 839 840 private void onSecondaryPointerUp(MotionEvent ev) { 841 final int pointerIndex = (ev.getAction() & MotionEventCompat.ACTION_POINTER_INDEX_MASK) >> 842 MotionEventCompat.ACTION_POINTER_INDEX_SHIFT; 843 final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); 844 if (pointerId == mActivePointerId) { 845 // This was our active pointer going up. Choose a new 846 // active pointer and adjust accordingly. 847 // TODO: Make this decision more intelligent. 848 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 849 mLastMotionY = (int) MotionEventCompat.getY(ev, newPointerIndex); 850 mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); 851 if (mVelocityTracker != null) { 852 mVelocityTracker.clear(); 853 } 854 } 855 } 856 857 public boolean onGenericMotionEvent(MotionEvent event) { 858 if ((MotionEventCompat.getSource(event) & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) { 859 switch (event.getAction()) { 860 case MotionEventCompat.ACTION_SCROLL: { 861 if (!mIsBeingDragged) { 862 final float vscroll = MotionEventCompat.getAxisValue(event, 863 MotionEventCompat.AXIS_VSCROLL); 864 if (vscroll != 0) { 865 final int delta = (int) (vscroll * getVerticalScrollFactorCompat()); 866 final int range = getScrollRange(); 867 int oldScrollY = getScrollY(); 868 int newScrollY = oldScrollY - delta; 869 if (newScrollY < 0) { 870 newScrollY = 0; 871 } else if (newScrollY > range) { 872 newScrollY = range; 873 } 874 if (newScrollY != oldScrollY) { 875 super.scrollTo(getScrollX(), newScrollY); 876 return true; 877 } 878 } 879 } 880 } 881 } 882 } 883 return false; 884 } 885 886 private float getVerticalScrollFactorCompat() { 887 if (mVerticalScrollFactor == 0) { 888 TypedValue outValue = new TypedValue(); 889 final Context context = getContext(); 890 if (!context.getTheme().resolveAttribute( 891 android.R.attr.listPreferredItemHeight, outValue, true)) { 892 throw new IllegalStateException( 893 "Expected theme to define listPreferredItemHeight."); 894 } 895 mVerticalScrollFactor = outValue.getDimension( 896 context.getResources().getDisplayMetrics()); 897 } 898 return mVerticalScrollFactor; 899 } 900 901 protected void onOverScrolled(int scrollX, int scrollY, 902 boolean clampedX, boolean clampedY) { 903 super.scrollTo(scrollX, scrollY); 904 } 905 906 boolean overScrollByCompat(int deltaX, int deltaY, 907 int scrollX, int scrollY, 908 int scrollRangeX, int scrollRangeY, 909 int maxOverScrollX, int maxOverScrollY, 910 boolean isTouchEvent) { 911 final int overScrollMode = ViewCompat.getOverScrollMode(this); 912 final boolean canScrollHorizontal = 913 computeHorizontalScrollRange() > computeHorizontalScrollExtent(); 914 final boolean canScrollVertical = 915 computeVerticalScrollRange() > computeVerticalScrollExtent(); 916 final boolean overScrollHorizontal = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 917 (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal); 918 final boolean overScrollVertical = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 919 (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical); 920 921 int newScrollX = scrollX + deltaX; 922 if (!overScrollHorizontal) { 923 maxOverScrollX = 0; 924 } 925 926 int newScrollY = scrollY + deltaY; 927 if (!overScrollVertical) { 928 maxOverScrollY = 0; 929 } 930 931 // Clamp values if at the limits and record 932 final int left = -maxOverScrollX; 933 final int right = maxOverScrollX + scrollRangeX; 934 final int top = -maxOverScrollY; 935 final int bottom = maxOverScrollY + scrollRangeY; 936 937 boolean clampedX = false; 938 if (newScrollX > right) { 939 newScrollX = right; 940 clampedX = true; 941 } else if (newScrollX < left) { 942 newScrollX = left; 943 clampedX = true; 944 } 945 946 boolean clampedY = false; 947 if (newScrollY > bottom) { 948 newScrollY = bottom; 949 clampedY = true; 950 } else if (newScrollY < top) { 951 newScrollY = top; 952 clampedY = true; 953 } 954 955 if (clampedY) { 956 mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange()); 957 } 958 959 onOverScrolled(newScrollX, newScrollY, clampedX, clampedY); 960 961 return clampedX || clampedY; 962 } 963 964 private int getScrollRange() { 965 int scrollRange = 0; 966 if (getChildCount() > 0) { 967 View child = getChildAt(0); 968 scrollRange = Math.max(0, 969 child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop())); 970 } 971 return scrollRange; 972 } 973 974 /** 975 * <p> 976 * Finds the next focusable component that fits in the specified bounds. 977 * </p> 978 * 979 * @param topFocus look for a candidate is the one at the top of the bounds 980 * if topFocus is true, or at the bottom of the bounds if topFocus is 981 * false 982 * @param top the top offset of the bounds in which a focusable must be 983 * found 984 * @param bottom the bottom offset of the bounds in which a focusable must 985 * be found 986 * @return the next focusable component in the bounds or null if none can 987 * be found 988 */ 989 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 990 991 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 992 View focusCandidate = null; 993 994 /* 995 * A fully contained focusable is one where its top is below the bound's 996 * top, and its bottom is above the bound's bottom. A partially 997 * contained focusable is one where some part of it is within the 998 * bounds, but it also has some part that is not within bounds. A fully contained 999 * focusable is preferred to a partially contained focusable. 1000 */ 1001 boolean foundFullyContainedFocusable = false; 1002 1003 int count = focusables.size(); 1004 for (int i = 0; i < count; i++) { 1005 View view = focusables.get(i); 1006 int viewTop = view.getTop(); 1007 int viewBottom = view.getBottom(); 1008 1009 if (top < viewBottom && viewTop < bottom) { 1010 /* 1011 * the focusable is in the target area, it is a candidate for 1012 * focusing 1013 */ 1014 1015 final boolean viewIsFullyContained = (top < viewTop) && 1016 (viewBottom < bottom); 1017 1018 if (focusCandidate == null) { 1019 /* No candidate, take this one */ 1020 focusCandidate = view; 1021 foundFullyContainedFocusable = viewIsFullyContained; 1022 } else { 1023 final boolean viewIsCloserToBoundary = 1024 (topFocus && viewTop < focusCandidate.getTop()) || 1025 (!topFocus && viewBottom > focusCandidate 1026 .getBottom()); 1027 1028 if (foundFullyContainedFocusable) { 1029 if (viewIsFullyContained && viewIsCloserToBoundary) { 1030 /* 1031 * We're dealing with only fully contained views, so 1032 * it has to be closer to the boundary to beat our 1033 * candidate 1034 */ 1035 focusCandidate = view; 1036 } 1037 } else { 1038 if (viewIsFullyContained) { 1039 /* Any fully contained view beats a partially contained view */ 1040 focusCandidate = view; 1041 foundFullyContainedFocusable = true; 1042 } else if (viewIsCloserToBoundary) { 1043 /* 1044 * Partially contained view beats another partially 1045 * contained view if it's closer 1046 */ 1047 focusCandidate = view; 1048 } 1049 } 1050 } 1051 } 1052 } 1053 1054 return focusCandidate; 1055 } 1056 1057 /** 1058 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 1059 * method will scroll the view by one page up or down and give the focus 1060 * to the topmost/bottommost component in the new visible area. If no 1061 * component is a good candidate for focus, this scrollview reclaims the 1062 * focus.</p> 1063 * 1064 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1065 * to go one page up or 1066 * {@link android.view.View#FOCUS_DOWN} to go one page down 1067 * @return true if the key event is consumed by this method, false otherwise 1068 */ 1069 public boolean pageScroll(int direction) { 1070 boolean down = direction == View.FOCUS_DOWN; 1071 int height = getHeight(); 1072 1073 if (down) { 1074 mTempRect.top = getScrollY() + height; 1075 int count = getChildCount(); 1076 if (count > 0) { 1077 View view = getChildAt(count - 1); 1078 if (mTempRect.top + height > view.getBottom()) { 1079 mTempRect.top = view.getBottom() - height; 1080 } 1081 } 1082 } else { 1083 mTempRect.top = getScrollY() - height; 1084 if (mTempRect.top < 0) { 1085 mTempRect.top = 0; 1086 } 1087 } 1088 mTempRect.bottom = mTempRect.top + height; 1089 1090 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1091 } 1092 1093 /** 1094 * <p>Handles scrolling in response to a "home/end" shortcut press. This 1095 * method will scroll the view to the top or bottom and give the focus 1096 * to the topmost/bottommost component in the new visible area. If no 1097 * component is a good candidate for focus, this scrollview reclaims the 1098 * focus.</p> 1099 * 1100 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1101 * to go the top of the view or 1102 * {@link android.view.View#FOCUS_DOWN} to go the bottom 1103 * @return true if the key event is consumed by this method, false otherwise 1104 */ 1105 public boolean fullScroll(int direction) { 1106 boolean down = direction == View.FOCUS_DOWN; 1107 int height = getHeight(); 1108 1109 mTempRect.top = 0; 1110 mTempRect.bottom = height; 1111 1112 if (down) { 1113 int count = getChildCount(); 1114 if (count > 0) { 1115 View view = getChildAt(count - 1); 1116 mTempRect.bottom = view.getBottom() + getPaddingBottom(); 1117 mTempRect.top = mTempRect.bottom - height; 1118 } 1119 } 1120 1121 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1122 } 1123 1124 /** 1125 * <p>Scrolls the view to make the area defined by <code>top</code> and 1126 * <code>bottom</code> visible. This method attempts to give the focus 1127 * to a component visible in this area. If no component can be focused in 1128 * the new visible area, the focus is reclaimed by this ScrollView.</p> 1129 * 1130 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1131 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 1132 * @param top the top offset of the new area to be made visible 1133 * @param bottom the bottom offset of the new area to be made visible 1134 * @return true if the key event is consumed by this method, false otherwise 1135 */ 1136 private boolean scrollAndFocus(int direction, int top, int bottom) { 1137 boolean handled = true; 1138 1139 int height = getHeight(); 1140 int containerTop = getScrollY(); 1141 int containerBottom = containerTop + height; 1142 boolean up = direction == View.FOCUS_UP; 1143 1144 View newFocused = findFocusableViewInBounds(up, top, bottom); 1145 if (newFocused == null) { 1146 newFocused = this; 1147 } 1148 1149 if (top >= containerTop && bottom <= containerBottom) { 1150 handled = false; 1151 } else { 1152 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1153 doScrollY(delta); 1154 } 1155 1156 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1157 1158 return handled; 1159 } 1160 1161 /** 1162 * Handle scrolling in response to an up or down arrow click. 1163 * 1164 * @param direction The direction corresponding to the arrow key that was 1165 * pressed 1166 * @return True if we consumed the event, false otherwise 1167 */ 1168 public boolean arrowScroll(int direction) { 1169 1170 View currentFocused = findFocus(); 1171 if (currentFocused == this) currentFocused = null; 1172 1173 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1174 1175 final int maxJump = getMaxScrollAmount(); 1176 1177 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1178 nextFocused.getDrawingRect(mTempRect); 1179 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1180 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1181 doScrollY(scrollDelta); 1182 nextFocused.requestFocus(direction); 1183 } else { 1184 // no new focus 1185 int scrollDelta = maxJump; 1186 1187 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1188 scrollDelta = getScrollY(); 1189 } else if (direction == View.FOCUS_DOWN) { 1190 if (getChildCount() > 0) { 1191 int daBottom = getChildAt(0).getBottom(); 1192 int screenBottom = getScrollY() + getHeight() - getPaddingBottom(); 1193 if (daBottom - screenBottom < maxJump) { 1194 scrollDelta = daBottom - screenBottom; 1195 } 1196 } 1197 } 1198 if (scrollDelta == 0) { 1199 return false; 1200 } 1201 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1202 } 1203 1204 if (currentFocused != null && currentFocused.isFocused() 1205 && isOffScreen(currentFocused)) { 1206 // previously focused item still has focus and is off screen, give 1207 // it up (take it back to ourselves) 1208 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1209 // sure to 1210 // get it) 1211 final int descendantFocusability = getDescendantFocusability(); // save 1212 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1213 requestFocus(); 1214 setDescendantFocusability(descendantFocusability); // restore 1215 } 1216 return true; 1217 } 1218 1219 /** 1220 * @return whether the descendant of this scroll view is scrolled off 1221 * screen. 1222 */ 1223 private boolean isOffScreen(View descendant) { 1224 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1225 } 1226 1227 /** 1228 * @return whether the descendant of this scroll view is within delta 1229 * pixels of being on the screen. 1230 */ 1231 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1232 descendant.getDrawingRect(mTempRect); 1233 offsetDescendantRectToMyCoords(descendant, mTempRect); 1234 1235 return (mTempRect.bottom + delta) >= getScrollY() 1236 && (mTempRect.top - delta) <= (getScrollY() + height); 1237 } 1238 1239 /** 1240 * Smooth scroll by a Y delta 1241 * 1242 * @param delta the number of pixels to scroll by on the Y axis 1243 */ 1244 private void doScrollY(int delta) { 1245 if (delta != 0) { 1246 if (mSmoothScrollingEnabled) { 1247 smoothScrollBy(0, delta); 1248 } else { 1249 scrollBy(0, delta); 1250 } 1251 } 1252 } 1253 1254 /** 1255 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1256 * 1257 * @param dx the number of pixels to scroll by on the X axis 1258 * @param dy the number of pixels to scroll by on the Y axis 1259 */ 1260 public final void smoothScrollBy(int dx, int dy) { 1261 if (getChildCount() == 0) { 1262 // Nothing to do. 1263 return; 1264 } 1265 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1266 if (duration > ANIMATED_SCROLL_GAP) { 1267 final int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1268 final int bottom = getChildAt(0).getHeight(); 1269 final int maxY = Math.max(0, bottom - height); 1270 final int scrollY = getScrollY(); 1271 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1272 1273 mScroller.startScroll(getScrollX(), scrollY, 0, dy); 1274 ViewCompat.postInvalidateOnAnimation(this); 1275 } else { 1276 if (!mScroller.isFinished()) { 1277 mScroller.abortAnimation(); 1278 } 1279 scrollBy(dx, dy); 1280 } 1281 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1282 } 1283 1284 /** 1285 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1286 * 1287 * @param x the position where to scroll on the X axis 1288 * @param y the position where to scroll on the Y axis 1289 */ 1290 public final void smoothScrollTo(int x, int y) { 1291 smoothScrollBy(x - getScrollX(), y - getScrollY()); 1292 } 1293 1294 /** 1295 * <p>The scroll range of a scroll view is the overall height of all of its 1296 * children.</p> 1297 */ 1298 @Override 1299 protected int computeVerticalScrollRange() { 1300 final int count = getChildCount(); 1301 final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop(); 1302 if (count == 0) { 1303 return contentHeight; 1304 } 1305 1306 int scrollRange = getChildAt(0).getBottom(); 1307 final int scrollY = getScrollY(); 1308 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1309 if (scrollY < 0) { 1310 scrollRange -= scrollY; 1311 } else if (scrollY > overscrollBottom) { 1312 scrollRange += scrollY - overscrollBottom; 1313 } 1314 1315 return scrollRange; 1316 } 1317 1318 @Override 1319 protected int computeVerticalScrollOffset() { 1320 return Math.max(0, super.computeVerticalScrollOffset()); 1321 } 1322 1323 @Override 1324 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1325 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1326 1327 int childWidthMeasureSpec; 1328 int childHeightMeasureSpec; 1329 1330 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() 1331 + getPaddingRight(), lp.width); 1332 1333 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1334 1335 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1336 } 1337 1338 @Override 1339 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1340 int parentHeightMeasureSpec, int heightUsed) { 1341 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1342 1343 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1344 getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin 1345 + widthUsed, lp.width); 1346 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1347 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1348 1349 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1350 } 1351 1352 @Override 1353 public void computeScroll() { 1354 if (mScroller.computeScrollOffset()) { 1355 int oldX = getScrollX(); 1356 int oldY = getScrollY(); 1357 int x = mScroller.getCurrX(); 1358 int y = mScroller.getCurrY(); 1359 1360 if (oldX != x || oldY != y) { 1361 final int range = getScrollRange(); 1362 final int overscrollMode = ViewCompat.getOverScrollMode(this); 1363 final boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 1364 (overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1365 1366 overScrollByCompat(x - oldX, y - oldY, oldX, oldY, 0, range, 1367 0, 0, false); 1368 1369 if (canOverscroll) { 1370 ensureGlows(); 1371 if (y <= 0 && oldY > 0) { 1372 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1373 } else if (y >= range && oldY < range) { 1374 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1375 } 1376 } 1377 } 1378 } 1379 } 1380 1381 /** 1382 * Scrolls the view to the given child. 1383 * 1384 * @param child the View to scroll to 1385 */ 1386 private void scrollToChild(View child) { 1387 child.getDrawingRect(mTempRect); 1388 1389 /* Offset from child's local coordinates to ScrollView coordinates */ 1390 offsetDescendantRectToMyCoords(child, mTempRect); 1391 1392 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1393 1394 if (scrollDelta != 0) { 1395 scrollBy(0, scrollDelta); 1396 } 1397 } 1398 1399 /** 1400 * If rect is off screen, scroll just enough to get it (or at least the 1401 * first screen size chunk of it) on screen. 1402 * 1403 * @param rect The rectangle. 1404 * @param immediate True to scroll immediately without animation 1405 * @return true if scrolling was performed 1406 */ 1407 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1408 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1409 final boolean scroll = delta != 0; 1410 if (scroll) { 1411 if (immediate) { 1412 scrollBy(0, delta); 1413 } else { 1414 smoothScrollBy(0, delta); 1415 } 1416 } 1417 return scroll; 1418 } 1419 1420 /** 1421 * Compute the amount to scroll in the Y direction in order to get 1422 * a rectangle completely on the screen (or, if taller than the screen, 1423 * at least the first screen size chunk of it). 1424 * 1425 * @param rect The rect. 1426 * @return The scroll delta. 1427 */ 1428 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1429 if (getChildCount() == 0) return 0; 1430 1431 int height = getHeight(); 1432 int screenTop = getScrollY(); 1433 int screenBottom = screenTop + height; 1434 1435 int fadingEdge = getVerticalFadingEdgeLength(); 1436 1437 // leave room for top fading edge as long as rect isn't at very top 1438 if (rect.top > 0) { 1439 screenTop += fadingEdge; 1440 } 1441 1442 // leave room for bottom fading edge as long as rect isn't at very bottom 1443 if (rect.bottom < getChildAt(0).getHeight()) { 1444 screenBottom -= fadingEdge; 1445 } 1446 1447 int scrollYDelta = 0; 1448 1449 if (rect.bottom > screenBottom && rect.top > screenTop) { 1450 // need to move down to get it in view: move down just enough so 1451 // that the entire rectangle is in view (or at least the first 1452 // screen size chunk). 1453 1454 if (rect.height() > height) { 1455 // just enough to get screen size chunk on 1456 scrollYDelta += (rect.top - screenTop); 1457 } else { 1458 // get entire rect at bottom of screen 1459 scrollYDelta += (rect.bottom - screenBottom); 1460 } 1461 1462 // make sure we aren't scrolling beyond the end of our content 1463 int bottom = getChildAt(0).getBottom(); 1464 int distanceToBottom = bottom - screenBottom; 1465 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1466 1467 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1468 // need to move up to get it in view: move up just enough so that 1469 // entire rectangle is in view (or at least the first screen 1470 // size chunk of it). 1471 1472 if (rect.height() > height) { 1473 // screen size chunk 1474 scrollYDelta -= (screenBottom - rect.bottom); 1475 } else { 1476 // entire rect at top 1477 scrollYDelta -= (screenTop - rect.top); 1478 } 1479 1480 // make sure we aren't scrolling any further than the top our content 1481 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1482 } 1483 return scrollYDelta; 1484 } 1485 1486 @Override 1487 public void requestChildFocus(View child, View focused) { 1488 if (!mIsLayoutDirty) { 1489 scrollToChild(focused); 1490 } else { 1491 // The child may not be laid out yet, we can't compute the scroll yet 1492 mChildToScrollTo = focused; 1493 } 1494 super.requestChildFocus(child, focused); 1495 } 1496 1497 1498 /** 1499 * When looking for focus in children of a scroll view, need to be a little 1500 * more careful not to give focus to something that is scrolled off screen. 1501 * 1502 * This is more expensive than the default {@link android.view.ViewGroup} 1503 * implementation, otherwise this behavior might have been made the default. 1504 */ 1505 @Override 1506 protected boolean onRequestFocusInDescendants(int direction, 1507 Rect previouslyFocusedRect) { 1508 1509 // convert from forward / backward notation to up / down / left / right 1510 // (ugh). 1511 if (direction == View.FOCUS_FORWARD) { 1512 direction = View.FOCUS_DOWN; 1513 } else if (direction == View.FOCUS_BACKWARD) { 1514 direction = View.FOCUS_UP; 1515 } 1516 1517 final View nextFocus = previouslyFocusedRect == null ? 1518 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1519 FocusFinder.getInstance().findNextFocusFromRect(this, 1520 previouslyFocusedRect, direction); 1521 1522 if (nextFocus == null) { 1523 return false; 1524 } 1525 1526 if (isOffScreen(nextFocus)) { 1527 return false; 1528 } 1529 1530 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1531 } 1532 1533 @Override 1534 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1535 boolean immediate) { 1536 // offset into coordinate space of this scroll view 1537 rectangle.offset(child.getLeft() - child.getScrollX(), 1538 child.getTop() - child.getScrollY()); 1539 1540 return scrollToChildRect(rectangle, immediate); 1541 } 1542 1543 @Override 1544 public void requestLayout() { 1545 mIsLayoutDirty = true; 1546 super.requestLayout(); 1547 } 1548 1549 @Override 1550 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1551 super.onLayout(changed, l, t, r, b); 1552 mIsLayoutDirty = false; 1553 // Give a child focus if it needs it 1554 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1555 scrollToChild(mChildToScrollTo); 1556 } 1557 mChildToScrollTo = null; 1558 1559 if (!mIsLaidOut) { 1560 if (mSavedState != null) { 1561 scrollTo(getScrollX(), mSavedState.scrollPosition); 1562 mSavedState = null; 1563 } // mScrollY default value is "0" 1564 1565 final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; 1566 final int scrollRange = Math.max(0, 1567 childHeight - (b - t - getPaddingBottom() - getPaddingTop())); 1568 1569 // Don't forget to clamp 1570 if (getScrollY() > scrollRange) { 1571 scrollTo(getScrollX(), scrollRange); 1572 } else if (getScrollY() < 0) { 1573 scrollTo(getScrollX(), 0); 1574 } 1575 } 1576 1577 // Calling this with the present values causes it to re-claim them 1578 scrollTo(getScrollX(), getScrollY()); 1579 mIsLaidOut = true; 1580 } 1581 1582 @Override 1583 public void onAttachedToWindow() { 1584 mIsLaidOut = false; 1585 } 1586 1587 @Override 1588 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1589 super.onSizeChanged(w, h, oldw, oldh); 1590 1591 View currentFocused = findFocus(); 1592 if (null == currentFocused || this == currentFocused) 1593 return; 1594 1595 // If the currently-focused view was visible on the screen when the 1596 // screen was at the old height, then scroll the screen to make that 1597 // view visible with the new screen height. 1598 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1599 currentFocused.getDrawingRect(mTempRect); 1600 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1601 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1602 doScrollY(scrollDelta); 1603 } 1604 } 1605 1606 /** 1607 * Return true if child is a descendant of parent, (or equal to the parent). 1608 */ 1609 private static boolean isViewDescendantOf(View child, View parent) { 1610 if (child == parent) { 1611 return true; 1612 } 1613 1614 final ViewParent theParent = child.getParent(); 1615 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1616 } 1617 1618 /** 1619 * Fling the scroll view 1620 * 1621 * @param velocityY The initial velocity in the Y direction. Positive 1622 * numbers mean that the finger/cursor is moving down the screen, 1623 * which means we want to scroll towards the top. 1624 */ 1625 public void fling(int velocityY) { 1626 if (getChildCount() > 0) { 1627 int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1628 int bottom = getChildAt(0).getHeight(); 1629 1630 mScroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0, 1631 Math.max(0, bottom - height), 0, height/2); 1632 1633 ViewCompat.postInvalidateOnAnimation(this); 1634 } 1635 } 1636 1637 private void flingWithNestedDispatch(int velocityY) { 1638 final int scrollY = getScrollY(); 1639 final boolean canFling = (scrollY > 0 || velocityY > 0) && 1640 (scrollY < getScrollRange() || velocityY < 0); 1641 if (!dispatchNestedPreFling(0, velocityY)) { 1642 dispatchNestedFling(0, velocityY, canFling); 1643 if (canFling) { 1644 fling(velocityY); 1645 } 1646 } 1647 } 1648 1649 private void endDrag() { 1650 mIsBeingDragged = false; 1651 1652 recycleVelocityTracker(); 1653 stopNestedScroll(); 1654 1655 if (mEdgeGlowTop != null) { 1656 mEdgeGlowTop.onRelease(); 1657 mEdgeGlowBottom.onRelease(); 1658 } 1659 } 1660 1661 /** 1662 * {@inheritDoc} 1663 * 1664 * <p>This version also clamps the scrolling to the bounds of our child. 1665 */ 1666 @Override 1667 public void scrollTo(int x, int y) { 1668 // we rely on the fact the View.scrollBy calls scrollTo. 1669 if (getChildCount() > 0) { 1670 View child = getChildAt(0); 1671 x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); 1672 y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); 1673 if (x != getScrollX() || y != getScrollY()) { 1674 super.scrollTo(x, y); 1675 } 1676 } 1677 } 1678 1679 private void ensureGlows() { 1680 if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) { 1681 if (mEdgeGlowTop == null) { 1682 Context context = getContext(); 1683 mEdgeGlowTop = new EdgeEffectCompat(context); 1684 mEdgeGlowBottom = new EdgeEffectCompat(context); 1685 } 1686 } else { 1687 mEdgeGlowTop = null; 1688 mEdgeGlowBottom = null; 1689 } 1690 } 1691 1692 @Override 1693 public void draw(Canvas canvas) { 1694 super.draw(canvas); 1695 if (mEdgeGlowTop != null) { 1696 final int scrollY = getScrollY(); 1697 if (!mEdgeGlowTop.isFinished()) { 1698 final int restoreCount = canvas.save(); 1699 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1700 1701 canvas.translate(getPaddingLeft(), Math.min(0, scrollY)); 1702 mEdgeGlowTop.setSize(width, getHeight()); 1703 if (mEdgeGlowTop.draw(canvas)) { 1704 ViewCompat.postInvalidateOnAnimation(this); 1705 } 1706 canvas.restoreToCount(restoreCount); 1707 } 1708 if (!mEdgeGlowBottom.isFinished()) { 1709 final int restoreCount = canvas.save(); 1710 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1711 final int height = getHeight(); 1712 1713 canvas.translate(-width + getPaddingLeft(), 1714 Math.max(getScrollRange(), scrollY) + height); 1715 canvas.rotate(180, width, 0); 1716 mEdgeGlowBottom.setSize(width, height); 1717 if (mEdgeGlowBottom.draw(canvas)) { 1718 ViewCompat.postInvalidateOnAnimation(this); 1719 } 1720 canvas.restoreToCount(restoreCount); 1721 } 1722 } 1723 } 1724 1725 private static int clamp(int n, int my, int child) { 1726 if (my >= child || n < 0) { 1727 /* my >= child is this case: 1728 * |--------------- me ---------------| 1729 * |------ child ------| 1730 * or 1731 * |--------------- me ---------------| 1732 * |------ child ------| 1733 * or 1734 * |--------------- me ---------------| 1735 * |------ child ------| 1736 * 1737 * n < 0 is this case: 1738 * |------ me ------| 1739 * |-------- child --------| 1740 * |-- mScrollX --| 1741 */ 1742 return 0; 1743 } 1744 if ((my+n) > child) { 1745 /* this case: 1746 * |------ me ------| 1747 * |------ child ------| 1748 * |-- mScrollX --| 1749 */ 1750 return child-my; 1751 } 1752 return n; 1753 } 1754 1755 @Override 1756 protected void onRestoreInstanceState(Parcelable state) { 1757 SavedState ss = (SavedState) state; 1758 super.onRestoreInstanceState(ss.getSuperState()); 1759 mSavedState = ss; 1760 requestLayout(); 1761 } 1762 1763 @Override 1764 protected Parcelable onSaveInstanceState() { 1765 Parcelable superState = super.onSaveInstanceState(); 1766 SavedState ss = new SavedState(superState); 1767 ss.scrollPosition = getScrollY(); 1768 return ss; 1769 } 1770 1771 static class SavedState extends BaseSavedState { 1772 public int scrollPosition; 1773 1774 SavedState(Parcelable superState) { 1775 super(superState); 1776 } 1777 1778 public SavedState(Parcel source) { 1779 super(source); 1780 scrollPosition = source.readInt(); 1781 } 1782 1783 @Override 1784 public void writeToParcel(Parcel dest, int flags) { 1785 super.writeToParcel(dest, flags); 1786 dest.writeInt(scrollPosition); 1787 } 1788 1789 @Override 1790 public String toString() { 1791 return "HorizontalScrollView.SavedState{" 1792 + Integer.toHexString(System.identityHashCode(this)) 1793 + " scrollPosition=" + scrollPosition + "}"; 1794 } 1795 1796 public static final Parcelable.Creator<SavedState> CREATOR 1797 = new Parcelable.Creator<SavedState>() { 1798 public SavedState createFromParcel(Parcel in) { 1799 return new SavedState(in); 1800 } 1801 1802 public SavedState[] newArray(int size) { 1803 return new SavedState[size]; 1804 } 1805 }; 1806 } 1807 1808 static class AccessibilityDelegate extends AccessibilityDelegateCompat { 1809 @Override 1810 public boolean performAccessibilityAction(View host, int action, Bundle arguments) { 1811 if (super.performAccessibilityAction(host, action, arguments)) { 1812 return true; 1813 } 1814 final NestedScrollView nsvHost = (NestedScrollView) host; 1815 if (!nsvHost.isEnabled()) { 1816 return false; 1817 } 1818 switch (action) { 1819 case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: { 1820 final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() 1821 - nsvHost.getPaddingTop(); 1822 final int targetScrollY = Math.min(nsvHost.getScrollY() + viewportHeight, 1823 nsvHost.getScrollRange()); 1824 if (targetScrollY != nsvHost.getScrollY()) { 1825 nsvHost.smoothScrollTo(0, targetScrollY); 1826 return true; 1827 } 1828 } 1829 return false; 1830 case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: { 1831 final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() 1832 - nsvHost.getPaddingTop(); 1833 final int targetScrollY = Math.max(nsvHost.getScrollY() - viewportHeight, 0); 1834 if (targetScrollY != nsvHost.getScrollY()) { 1835 nsvHost.smoothScrollTo(0, targetScrollY); 1836 return true; 1837 } 1838 } 1839 return false; 1840 } 1841 return false; 1842 } 1843 1844 @Override 1845 public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { 1846 super.onInitializeAccessibilityNodeInfo(host, info); 1847 final NestedScrollView nsvHost = (NestedScrollView) host; 1848 info.setClassName(ScrollView.class.getName()); 1849 if (nsvHost.isEnabled()) { 1850 final int scrollRange = nsvHost.getScrollRange(); 1851 if (scrollRange > 0) { 1852 info.setScrollable(true); 1853 if (nsvHost.getScrollY() > 0) { 1854 info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); 1855 } 1856 if (nsvHost.getScrollY() < scrollRange) { 1857 info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); 1858 } 1859 } 1860 } 1861 } 1862 1863 @Override 1864 public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { 1865 super.onInitializeAccessibilityEvent(host, event); 1866 final NestedScrollView nsvHost = (NestedScrollView) host; 1867 event.setClassName(ScrollView.class.getName()); 1868 final AccessibilityRecordCompat record = AccessibilityEventCompat.asRecord(event); 1869 final boolean scrollable = nsvHost.getScrollRange() > 0; 1870 record.setScrollable(scrollable); 1871 record.setScrollX(nsvHost.getScrollX()); 1872 record.setScrollY(nsvHost.getScrollY()); 1873 record.setMaxScrollX(nsvHost.getScrollX()); 1874 record.setMaxScrollY(nsvHost.getScrollRange()); 1875 } 1876 } 1877} 1878