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