NestedScrollView.java revision 236bf5bc5041e4bf356eac3855fd4fcf72cd6994
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 * Set whether this ScrollView should stretch its content height to fill the viewport or not. 440 * 441 * @param fillViewport True to stretch the content's height to the viewport's 442 * boundaries, false otherwise. 443 * 444 * @attr name android:fillViewport 445 */ 446 public void setFillViewport(boolean fillViewport) { 447 if (fillViewport != mFillViewport) { 448 mFillViewport = fillViewport; 449 requestLayout(); 450 } 451 } 452 453 /** 454 * @return Whether arrow scrolling will animate its transition. 455 */ 456 public boolean isSmoothScrollingEnabled() { 457 return mSmoothScrollingEnabled; 458 } 459 460 /** 461 * Set whether arrow scrolling will animate its transition. 462 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 463 */ 464 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 465 mSmoothScrollingEnabled = smoothScrollingEnabled; 466 } 467 468 @Override 469 protected void onScrollChanged(int l, int t, int oldl, int oldt) { 470 super.onScrollChanged(l, t, oldl, oldt); 471 472 if (mOnScrollChangeListener != null) { 473 mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt); 474 } 475 } 476 477 @Override 478 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 479 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 480 481 if (!mFillViewport) { 482 return; 483 } 484 485 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 486 if (heightMode == MeasureSpec.UNSPECIFIED) { 487 return; 488 } 489 490 if (getChildCount() > 0) { 491 final View child = getChildAt(0); 492 int height = getMeasuredHeight(); 493 if (child.getMeasuredHeight() < height) { 494 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 495 496 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, 497 getPaddingLeft() + getPaddingRight(), lp.width); 498 height -= getPaddingTop(); 499 height -= getPaddingBottom(); 500 int childHeightMeasureSpec = 501 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 502 503 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 504 } 505 } 506 } 507 508 @Override 509 public boolean dispatchKeyEvent(KeyEvent event) { 510 // Let the focused view and/or our descendants get the key first 511 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 512 } 513 514 /** 515 * You can call this function yourself to have the scroll view perform 516 * scrolling from a key event, just as if the event had been dispatched to 517 * it by the view hierarchy. 518 * 519 * @param event The key event to execute. 520 * @return Return true if the event was handled, else false. 521 */ 522 public boolean executeKeyEvent(KeyEvent event) { 523 mTempRect.setEmpty(); 524 525 if (!canScroll()) { 526 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 527 View currentFocused = findFocus(); 528 if (currentFocused == this) currentFocused = null; 529 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 530 currentFocused, View.FOCUS_DOWN); 531 return nextFocused != null 532 && nextFocused != this 533 && nextFocused.requestFocus(View.FOCUS_DOWN); 534 } 535 return false; 536 } 537 538 boolean handled = false; 539 if (event.getAction() == KeyEvent.ACTION_DOWN) { 540 switch (event.getKeyCode()) { 541 case KeyEvent.KEYCODE_DPAD_UP: 542 if (!event.isAltPressed()) { 543 handled = arrowScroll(View.FOCUS_UP); 544 } else { 545 handled = fullScroll(View.FOCUS_UP); 546 } 547 break; 548 case KeyEvent.KEYCODE_DPAD_DOWN: 549 if (!event.isAltPressed()) { 550 handled = arrowScroll(View.FOCUS_DOWN); 551 } else { 552 handled = fullScroll(View.FOCUS_DOWN); 553 } 554 break; 555 case KeyEvent.KEYCODE_SPACE: 556 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 557 break; 558 } 559 } 560 561 return handled; 562 } 563 564 private boolean inChild(int x, int y) { 565 if (getChildCount() > 0) { 566 final int scrollY = getScrollY(); 567 final View child = getChildAt(0); 568 return !(y < child.getTop() - scrollY 569 || y >= child.getBottom() - scrollY 570 || x < child.getLeft() 571 || x >= child.getRight()); 572 } 573 return false; 574 } 575 576 private void initOrResetVelocityTracker() { 577 if (mVelocityTracker == null) { 578 mVelocityTracker = VelocityTracker.obtain(); 579 } else { 580 mVelocityTracker.clear(); 581 } 582 } 583 584 private void initVelocityTrackerIfNotExists() { 585 if (mVelocityTracker == null) { 586 mVelocityTracker = VelocityTracker.obtain(); 587 } 588 } 589 590 private void recycleVelocityTracker() { 591 if (mVelocityTracker != null) { 592 mVelocityTracker.recycle(); 593 mVelocityTracker = null; 594 } 595 } 596 597 @Override 598 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 599 if (disallowIntercept) { 600 recycleVelocityTracker(); 601 } 602 super.requestDisallowInterceptTouchEvent(disallowIntercept); 603 } 604 605 606 @Override 607 public boolean onInterceptTouchEvent(MotionEvent ev) { 608 /* 609 * This method JUST determines whether we want to intercept the motion. 610 * If we return true, onMotionEvent will be called and we do the actual 611 * scrolling there. 612 */ 613 614 /* 615 * Shortcut the most recurring case: the user is in the dragging 616 * state and he is moving his finger. We want to intercept this 617 * motion. 618 */ 619 final int action = ev.getAction(); 620 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 621 return true; 622 } 623 624 switch (action & MotionEventCompat.ACTION_MASK) { 625 case MotionEvent.ACTION_MOVE: { 626 /* 627 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 628 * whether the user has moved far enough from his original down touch. 629 */ 630 631 /* 632 * Locally do absolute value. mLastMotionY is set to the y value 633 * of the down event. 634 */ 635 final int activePointerId = mActivePointerId; 636 if (activePointerId == INVALID_POINTER) { 637 // If we don't have a valid id, the touch down wasn't on content. 638 break; 639 } 640 641 final int pointerIndex = ev.findPointerIndex(activePointerId); 642 if (pointerIndex == -1) { 643 Log.e(TAG, "Invalid pointerId=" + activePointerId 644 + " in onInterceptTouchEvent"); 645 break; 646 } 647 648 final int y = (int) ev.getY(pointerIndex); 649 final int yDiff = Math.abs(y - mLastMotionY); 650 if (yDiff > mTouchSlop 651 && (getNestedScrollAxes() & ViewCompat.SCROLL_AXIS_VERTICAL) == 0) { 652 mIsBeingDragged = true; 653 mLastMotionY = y; 654 initVelocityTrackerIfNotExists(); 655 mVelocityTracker.addMovement(ev); 656 mNestedYOffset = 0; 657 final ViewParent parent = getParent(); 658 if (parent != null) { 659 parent.requestDisallowInterceptTouchEvent(true); 660 } 661 } 662 break; 663 } 664 665 case MotionEvent.ACTION_DOWN: { 666 final int y = (int) ev.getY(); 667 if (!inChild((int) ev.getX(), (int) y)) { 668 mIsBeingDragged = false; 669 recycleVelocityTracker(); 670 break; 671 } 672 673 /* 674 * Remember location of down touch. 675 * ACTION_DOWN always refers to pointer index 0. 676 */ 677 mLastMotionY = y; 678 mActivePointerId = ev.getPointerId(0); 679 680 initOrResetVelocityTracker(); 681 mVelocityTracker.addMovement(ev); 682 /* 683 * If being flinged and user touches the screen, initiate drag; 684 * otherwise don't. mScroller.isFinished should be false when 685 * being flinged. We need to call computeScrollOffset() first so that 686 * isFinished() is correct. 687 */ 688 mScroller.computeScrollOffset(); 689 mIsBeingDragged = !mScroller.isFinished(); 690 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 691 break; 692 } 693 694 case MotionEvent.ACTION_CANCEL: 695 case MotionEvent.ACTION_UP: 696 /* Release the drag */ 697 mIsBeingDragged = false; 698 mActivePointerId = INVALID_POINTER; 699 recycleVelocityTracker(); 700 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { 701 ViewCompat.postInvalidateOnAnimation(this); 702 } 703 stopNestedScroll(); 704 break; 705 case MotionEventCompat.ACTION_POINTER_UP: 706 onSecondaryPointerUp(ev); 707 break; 708 } 709 710 /* 711 * The only time we want to intercept motion events is if we are in the 712 * drag mode. 713 */ 714 return mIsBeingDragged; 715 } 716 717 @Override 718 public boolean onTouchEvent(MotionEvent ev) { 719 initVelocityTrackerIfNotExists(); 720 721 MotionEvent vtev = MotionEvent.obtain(ev); 722 723 final int actionMasked = MotionEventCompat.getActionMasked(ev); 724 725 if (actionMasked == MotionEvent.ACTION_DOWN) { 726 mNestedYOffset = 0; 727 } 728 vtev.offsetLocation(0, mNestedYOffset); 729 730 switch (actionMasked) { 731 case MotionEvent.ACTION_DOWN: { 732 if (getChildCount() == 0) { 733 return false; 734 } 735 if ((mIsBeingDragged = !mScroller.isFinished())) { 736 final ViewParent parent = getParent(); 737 if (parent != null) { 738 parent.requestDisallowInterceptTouchEvent(true); 739 } 740 } 741 742 /* 743 * If being flinged and user touches, stop the fling. isFinished 744 * will be false if being flinged. 745 */ 746 if (!mScroller.isFinished()) { 747 mScroller.abortAnimation(); 748 } 749 750 // Remember where the motion event started 751 mLastMotionY = (int) ev.getY(); 752 mActivePointerId = ev.getPointerId(0); 753 startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); 754 break; 755 } 756 case MotionEvent.ACTION_MOVE: 757 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 758 if (activePointerIndex == -1) { 759 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 760 break; 761 } 762 763 final int y = (int) ev.getY(activePointerIndex); 764 int deltaY = mLastMotionY - y; 765 if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) { 766 deltaY -= mScrollConsumed[1]; 767 vtev.offsetLocation(0, mScrollOffset[1]); 768 mNestedYOffset += mScrollOffset[1]; 769 } 770 if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { 771 final ViewParent parent = getParent(); 772 if (parent != null) { 773 parent.requestDisallowInterceptTouchEvent(true); 774 } 775 mIsBeingDragged = true; 776 if (deltaY > 0) { 777 deltaY -= mTouchSlop; 778 } else { 779 deltaY += mTouchSlop; 780 } 781 } 782 if (mIsBeingDragged) { 783 // Scroll to follow the motion event 784 mLastMotionY = y - mScrollOffset[1]; 785 786 final int oldY = getScrollY(); 787 final int range = getScrollRange(); 788 final int overscrollMode = ViewCompat.getOverScrollMode(this); 789 boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 790 (overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && 791 range > 0); 792 793 // Calling overScrollByCompat will call onOverScrolled, which 794 // calls onScrollChanged if applicable. 795 if (overScrollByCompat(0, deltaY, 0, getScrollY(), 0, range, 0, 796 0, true) && !hasNestedScrollingParent()) { 797 // Break our velocity if we hit a scroll barrier. 798 mVelocityTracker.clear(); 799 } 800 801 final int scrolledDeltaY = getScrollY() - oldY; 802 final int unconsumedY = deltaY - scrolledDeltaY; 803 if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) { 804 mLastMotionY -= mScrollOffset[1]; 805 vtev.offsetLocation(0, mScrollOffset[1]); 806 mNestedYOffset += mScrollOffset[1]; 807 } else if (canOverscroll) { 808 ensureGlows(); 809 final int pulledToY = oldY + deltaY; 810 if (pulledToY < 0) { 811 mEdgeGlowTop.onPull((float) deltaY / getHeight(), 812 ev.getX(activePointerIndex) / getWidth()); 813 if (!mEdgeGlowBottom.isFinished()) { 814 mEdgeGlowBottom.onRelease(); 815 } 816 } else if (pulledToY > range) { 817 mEdgeGlowBottom.onPull((float) deltaY / getHeight(), 818 1.f - ev.getX(activePointerIndex) 819 / getWidth()); 820 if (!mEdgeGlowTop.isFinished()) { 821 mEdgeGlowTop.onRelease(); 822 } 823 } 824 if (mEdgeGlowTop != null 825 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 826 ViewCompat.postInvalidateOnAnimation(this); 827 } 828 } 829 } 830 break; 831 case MotionEvent.ACTION_UP: 832 if (mIsBeingDragged) { 833 final VelocityTracker velocityTracker = mVelocityTracker; 834 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 835 int initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, 836 mActivePointerId); 837 838 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 839 flingWithNestedDispatch(-initialVelocity); 840 } else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 841 getScrollRange())) { 842 ViewCompat.postInvalidateOnAnimation(this); 843 } 844 } 845 mActivePointerId = INVALID_POINTER; 846 endDrag(); 847 break; 848 case MotionEvent.ACTION_CANCEL: 849 if (mIsBeingDragged && getChildCount() > 0) { 850 if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 851 getScrollRange())) { 852 ViewCompat.postInvalidateOnAnimation(this); 853 } 854 } 855 mActivePointerId = INVALID_POINTER; 856 endDrag(); 857 break; 858 case MotionEventCompat.ACTION_POINTER_DOWN: { 859 final int index = MotionEventCompat.getActionIndex(ev); 860 mLastMotionY = (int) ev.getY(index); 861 mActivePointerId = ev.getPointerId(index); 862 break; 863 } 864 case MotionEventCompat.ACTION_POINTER_UP: 865 onSecondaryPointerUp(ev); 866 mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId)); 867 break; 868 } 869 870 if (mVelocityTracker != null) { 871 mVelocityTracker.addMovement(vtev); 872 } 873 vtev.recycle(); 874 return true; 875 } 876 877 private void onSecondaryPointerUp(MotionEvent ev) { 878 final int pointerIndex = (ev.getAction() & MotionEventCompat.ACTION_POINTER_INDEX_MASK) >> 879 MotionEventCompat.ACTION_POINTER_INDEX_SHIFT; 880 final int pointerId = ev.getPointerId(pointerIndex); 881 if (pointerId == mActivePointerId) { 882 // This was our active pointer going up. Choose a new 883 // active pointer and adjust accordingly. 884 // TODO: Make this decision more intelligent. 885 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 886 mLastMotionY = (int) ev.getY(newPointerIndex); 887 mActivePointerId = ev.getPointerId(newPointerIndex); 888 if (mVelocityTracker != null) { 889 mVelocityTracker.clear(); 890 } 891 } 892 } 893 894 public boolean onGenericMotionEvent(MotionEvent event) { 895 if ((event.getSource() & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) { 896 switch (event.getAction()) { 897 case MotionEventCompat.ACTION_SCROLL: { 898 if (!mIsBeingDragged) { 899 final float vscroll = MotionEventCompat.getAxisValue(event, 900 MotionEventCompat.AXIS_VSCROLL); 901 if (vscroll != 0) { 902 final int delta = (int) (vscroll * getVerticalScrollFactorCompat()); 903 final int range = getScrollRange(); 904 int oldScrollY = getScrollY(); 905 int newScrollY = oldScrollY - delta; 906 if (newScrollY < 0) { 907 newScrollY = 0; 908 } else if (newScrollY > range) { 909 newScrollY = range; 910 } 911 if (newScrollY != oldScrollY) { 912 super.scrollTo(getScrollX(), newScrollY); 913 return true; 914 } 915 } 916 } 917 } 918 } 919 } 920 return false; 921 } 922 923 private float getVerticalScrollFactorCompat() { 924 if (mVerticalScrollFactor == 0) { 925 TypedValue outValue = new TypedValue(); 926 final Context context = getContext(); 927 if (!context.getTheme().resolveAttribute( 928 android.R.attr.listPreferredItemHeight, outValue, true)) { 929 throw new IllegalStateException( 930 "Expected theme to define listPreferredItemHeight."); 931 } 932 mVerticalScrollFactor = outValue.getDimension( 933 context.getResources().getDisplayMetrics()); 934 } 935 return mVerticalScrollFactor; 936 } 937 938 @Override 939 protected void onOverScrolled(int scrollX, int scrollY, 940 boolean clampedX, boolean clampedY) { 941 super.scrollTo(scrollX, scrollY); 942 } 943 944 boolean overScrollByCompat(int deltaX, int deltaY, 945 int scrollX, int scrollY, 946 int scrollRangeX, int scrollRangeY, 947 int maxOverScrollX, int maxOverScrollY, 948 boolean isTouchEvent) { 949 final int overScrollMode = ViewCompat.getOverScrollMode(this); 950 final boolean canScrollHorizontal = 951 computeHorizontalScrollRange() > computeHorizontalScrollExtent(); 952 final boolean canScrollVertical = 953 computeVerticalScrollRange() > computeVerticalScrollExtent(); 954 final boolean overScrollHorizontal = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 955 (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal); 956 final boolean overScrollVertical = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 957 (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical); 958 959 int newScrollX = scrollX + deltaX; 960 if (!overScrollHorizontal) { 961 maxOverScrollX = 0; 962 } 963 964 int newScrollY = scrollY + deltaY; 965 if (!overScrollVertical) { 966 maxOverScrollY = 0; 967 } 968 969 // Clamp values if at the limits and record 970 final int left = -maxOverScrollX; 971 final int right = maxOverScrollX + scrollRangeX; 972 final int top = -maxOverScrollY; 973 final int bottom = maxOverScrollY + scrollRangeY; 974 975 boolean clampedX = false; 976 if (newScrollX > right) { 977 newScrollX = right; 978 clampedX = true; 979 } else if (newScrollX < left) { 980 newScrollX = left; 981 clampedX = true; 982 } 983 984 boolean clampedY = false; 985 if (newScrollY > bottom) { 986 newScrollY = bottom; 987 clampedY = true; 988 } else if (newScrollY < top) { 989 newScrollY = top; 990 clampedY = true; 991 } 992 993 if (clampedY) { 994 mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange()); 995 } 996 997 onOverScrolled(newScrollX, newScrollY, clampedX, clampedY); 998 999 return clampedX || clampedY; 1000 } 1001 1002 private int getScrollRange() { 1003 int scrollRange = 0; 1004 if (getChildCount() > 0) { 1005 View child = getChildAt(0); 1006 scrollRange = Math.max(0, 1007 child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop())); 1008 } 1009 return scrollRange; 1010 } 1011 1012 /** 1013 * <p> 1014 * Finds the next focusable component that fits in the specified bounds. 1015 * </p> 1016 * 1017 * @param topFocus look for a candidate is the one at the top of the bounds 1018 * if topFocus is true, or at the bottom of the bounds if topFocus is 1019 * false 1020 * @param top the top offset of the bounds in which a focusable must be 1021 * found 1022 * @param bottom the bottom offset of the bounds in which a focusable must 1023 * be found 1024 * @return the next focusable component in the bounds or null if none can 1025 * be found 1026 */ 1027 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 1028 1029 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 1030 View focusCandidate = null; 1031 1032 /* 1033 * A fully contained focusable is one where its top is below the bound's 1034 * top, and its bottom is above the bound's bottom. A partially 1035 * contained focusable is one where some part of it is within the 1036 * bounds, but it also has some part that is not within bounds. A fully contained 1037 * focusable is preferred to a partially contained focusable. 1038 */ 1039 boolean foundFullyContainedFocusable = false; 1040 1041 int count = focusables.size(); 1042 for (int i = 0; i < count; i++) { 1043 View view = focusables.get(i); 1044 int viewTop = view.getTop(); 1045 int viewBottom = view.getBottom(); 1046 1047 if (top < viewBottom && viewTop < bottom) { 1048 /* 1049 * the focusable is in the target area, it is a candidate for 1050 * focusing 1051 */ 1052 1053 final boolean viewIsFullyContained = (top < viewTop) && 1054 (viewBottom < bottom); 1055 1056 if (focusCandidate == null) { 1057 /* No candidate, take this one */ 1058 focusCandidate = view; 1059 foundFullyContainedFocusable = viewIsFullyContained; 1060 } else { 1061 final boolean viewIsCloserToBoundary = 1062 (topFocus && viewTop < focusCandidate.getTop()) || 1063 (!topFocus && viewBottom > focusCandidate 1064 .getBottom()); 1065 1066 if (foundFullyContainedFocusable) { 1067 if (viewIsFullyContained && viewIsCloserToBoundary) { 1068 /* 1069 * We're dealing with only fully contained views, so 1070 * it has to be closer to the boundary to beat our 1071 * candidate 1072 */ 1073 focusCandidate = view; 1074 } 1075 } else { 1076 if (viewIsFullyContained) { 1077 /* Any fully contained view beats a partially contained view */ 1078 focusCandidate = view; 1079 foundFullyContainedFocusable = true; 1080 } else if (viewIsCloserToBoundary) { 1081 /* 1082 * Partially contained view beats another partially 1083 * contained view if it's closer 1084 */ 1085 focusCandidate = view; 1086 } 1087 } 1088 } 1089 } 1090 } 1091 1092 return focusCandidate; 1093 } 1094 1095 /** 1096 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 1097 * method will scroll the view by one page up or down and give the focus 1098 * to the topmost/bottommost component in the new visible area. If no 1099 * component is a good candidate for focus, this scrollview reclaims the 1100 * focus.</p> 1101 * 1102 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1103 * to go one page up or 1104 * {@link android.view.View#FOCUS_DOWN} to go one page down 1105 * @return true if the key event is consumed by this method, false otherwise 1106 */ 1107 public boolean pageScroll(int direction) { 1108 boolean down = direction == View.FOCUS_DOWN; 1109 int height = getHeight(); 1110 1111 if (down) { 1112 mTempRect.top = getScrollY() + height; 1113 int count = getChildCount(); 1114 if (count > 0) { 1115 View view = getChildAt(count - 1); 1116 if (mTempRect.top + height > view.getBottom()) { 1117 mTempRect.top = view.getBottom() - height; 1118 } 1119 } 1120 } else { 1121 mTempRect.top = getScrollY() - height; 1122 if (mTempRect.top < 0) { 1123 mTempRect.top = 0; 1124 } 1125 } 1126 mTempRect.bottom = mTempRect.top + height; 1127 1128 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1129 } 1130 1131 /** 1132 * <p>Handles scrolling in response to a "home/end" shortcut press. This 1133 * method will scroll the view to the top or bottom and give the focus 1134 * to the topmost/bottommost component in the new visible area. If no 1135 * component is a good candidate for focus, this scrollview reclaims the 1136 * focus.</p> 1137 * 1138 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1139 * to go the top of the view or 1140 * {@link android.view.View#FOCUS_DOWN} to go the bottom 1141 * @return true if the key event is consumed by this method, false otherwise 1142 */ 1143 public boolean fullScroll(int direction) { 1144 boolean down = direction == View.FOCUS_DOWN; 1145 int height = getHeight(); 1146 1147 mTempRect.top = 0; 1148 mTempRect.bottom = height; 1149 1150 if (down) { 1151 int count = getChildCount(); 1152 if (count > 0) { 1153 View view = getChildAt(count - 1); 1154 mTempRect.bottom = view.getBottom() + getPaddingBottom(); 1155 mTempRect.top = mTempRect.bottom - height; 1156 } 1157 } 1158 1159 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1160 } 1161 1162 /** 1163 * <p>Scrolls the view to make the area defined by <code>top</code> and 1164 * <code>bottom</code> visible. This method attempts to give the focus 1165 * to a component visible in this area. If no component can be focused in 1166 * the new visible area, the focus is reclaimed by this ScrollView.</p> 1167 * 1168 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1169 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 1170 * @param top the top offset of the new area to be made visible 1171 * @param bottom the bottom offset of the new area to be made visible 1172 * @return true if the key event is consumed by this method, false otherwise 1173 */ 1174 private boolean scrollAndFocus(int direction, int top, int bottom) { 1175 boolean handled = true; 1176 1177 int height = getHeight(); 1178 int containerTop = getScrollY(); 1179 int containerBottom = containerTop + height; 1180 boolean up = direction == View.FOCUS_UP; 1181 1182 View newFocused = findFocusableViewInBounds(up, top, bottom); 1183 if (newFocused == null) { 1184 newFocused = this; 1185 } 1186 1187 if (top >= containerTop && bottom <= containerBottom) { 1188 handled = false; 1189 } else { 1190 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1191 doScrollY(delta); 1192 } 1193 1194 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1195 1196 return handled; 1197 } 1198 1199 /** 1200 * Handle scrolling in response to an up or down arrow click. 1201 * 1202 * @param direction The direction corresponding to the arrow key that was 1203 * pressed 1204 * @return True if we consumed the event, false otherwise 1205 */ 1206 public boolean arrowScroll(int direction) { 1207 1208 View currentFocused = findFocus(); 1209 if (currentFocused == this) currentFocused = null; 1210 1211 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1212 1213 final int maxJump = getMaxScrollAmount(); 1214 1215 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1216 nextFocused.getDrawingRect(mTempRect); 1217 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1218 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1219 doScrollY(scrollDelta); 1220 nextFocused.requestFocus(direction); 1221 } else { 1222 // no new focus 1223 int scrollDelta = maxJump; 1224 1225 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1226 scrollDelta = getScrollY(); 1227 } else if (direction == View.FOCUS_DOWN) { 1228 if (getChildCount() > 0) { 1229 int daBottom = getChildAt(0).getBottom(); 1230 int screenBottom = getScrollY() + getHeight() - getPaddingBottom(); 1231 if (daBottom - screenBottom < maxJump) { 1232 scrollDelta = daBottom - screenBottom; 1233 } 1234 } 1235 } 1236 if (scrollDelta == 0) { 1237 return false; 1238 } 1239 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1240 } 1241 1242 if (currentFocused != null && currentFocused.isFocused() 1243 && isOffScreen(currentFocused)) { 1244 // previously focused item still has focus and is off screen, give 1245 // it up (take it back to ourselves) 1246 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1247 // sure to 1248 // get it) 1249 final int descendantFocusability = getDescendantFocusability(); // save 1250 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1251 requestFocus(); 1252 setDescendantFocusability(descendantFocusability); // restore 1253 } 1254 return true; 1255 } 1256 1257 /** 1258 * @return whether the descendant of this scroll view is scrolled off 1259 * screen. 1260 */ 1261 private boolean isOffScreen(View descendant) { 1262 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1263 } 1264 1265 /** 1266 * @return whether the descendant of this scroll view is within delta 1267 * pixels of being on the screen. 1268 */ 1269 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1270 descendant.getDrawingRect(mTempRect); 1271 offsetDescendantRectToMyCoords(descendant, mTempRect); 1272 1273 return (mTempRect.bottom + delta) >= getScrollY() 1274 && (mTempRect.top - delta) <= (getScrollY() + height); 1275 } 1276 1277 /** 1278 * Smooth scroll by a Y delta 1279 * 1280 * @param delta the number of pixels to scroll by on the Y axis 1281 */ 1282 private void doScrollY(int delta) { 1283 if (delta != 0) { 1284 if (mSmoothScrollingEnabled) { 1285 smoothScrollBy(0, delta); 1286 } else { 1287 scrollBy(0, delta); 1288 } 1289 } 1290 } 1291 1292 /** 1293 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1294 * 1295 * @param dx the number of pixels to scroll by on the X axis 1296 * @param dy the number of pixels to scroll by on the Y axis 1297 */ 1298 public final void smoothScrollBy(int dx, int dy) { 1299 if (getChildCount() == 0) { 1300 // Nothing to do. 1301 return; 1302 } 1303 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1304 if (duration > ANIMATED_SCROLL_GAP) { 1305 final int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1306 final int bottom = getChildAt(0).getHeight(); 1307 final int maxY = Math.max(0, bottom - height); 1308 final int scrollY = getScrollY(); 1309 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1310 1311 mScroller.startScroll(getScrollX(), scrollY, 0, dy); 1312 ViewCompat.postInvalidateOnAnimation(this); 1313 } else { 1314 if (!mScroller.isFinished()) { 1315 mScroller.abortAnimation(); 1316 } 1317 scrollBy(dx, dy); 1318 } 1319 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1320 } 1321 1322 /** 1323 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1324 * 1325 * @param x the position where to scroll on the X axis 1326 * @param y the position where to scroll on the Y axis 1327 */ 1328 public final void smoothScrollTo(int x, int y) { 1329 smoothScrollBy(x - getScrollX(), y - getScrollY()); 1330 } 1331 1332 /** 1333 * <p>The scroll range of a scroll view is the overall height of all of its 1334 * children.</p> 1335 * @hide 1336 */ 1337 @Override 1338 public int computeVerticalScrollRange() { 1339 final int count = getChildCount(); 1340 final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop(); 1341 if (count == 0) { 1342 return contentHeight; 1343 } 1344 1345 int scrollRange = getChildAt(0).getBottom(); 1346 final int scrollY = getScrollY(); 1347 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1348 if (scrollY < 0) { 1349 scrollRange -= scrollY; 1350 } else if (scrollY > overscrollBottom) { 1351 scrollRange += scrollY - overscrollBottom; 1352 } 1353 1354 return scrollRange; 1355 } 1356 1357 /** @hide */ 1358 @Override 1359 public int computeVerticalScrollOffset() { 1360 return Math.max(0, super.computeVerticalScrollOffset()); 1361 } 1362 1363 /** @hide */ 1364 @Override 1365 public int computeVerticalScrollExtent() { 1366 return super.computeVerticalScrollExtent(); 1367 } 1368 1369 /** @hide */ 1370 @Override 1371 public int computeHorizontalScrollRange() { 1372 return super.computeHorizontalScrollRange(); 1373 } 1374 1375 /** @hide */ 1376 @Override 1377 public int computeHorizontalScrollOffset() { 1378 return super.computeHorizontalScrollOffset(); 1379 } 1380 1381 /** @hide */ 1382 @Override 1383 public int computeHorizontalScrollExtent() { 1384 return super.computeHorizontalScrollExtent(); 1385 } 1386 1387 @Override 1388 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1389 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1390 1391 int childWidthMeasureSpec; 1392 int childHeightMeasureSpec; 1393 1394 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() 1395 + getPaddingRight(), lp.width); 1396 1397 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1398 1399 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1400 } 1401 1402 @Override 1403 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1404 int parentHeightMeasureSpec, int heightUsed) { 1405 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1406 1407 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1408 getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin 1409 + widthUsed, lp.width); 1410 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1411 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1412 1413 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1414 } 1415 1416 @Override 1417 public void computeScroll() { 1418 if (mScroller.computeScrollOffset()) { 1419 int oldX = getScrollX(); 1420 int oldY = getScrollY(); 1421 int x = mScroller.getCurrX(); 1422 int y = mScroller.getCurrY(); 1423 1424 if (oldX != x || oldY != y) { 1425 final int range = getScrollRange(); 1426 final int overscrollMode = ViewCompat.getOverScrollMode(this); 1427 final boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS || 1428 (overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1429 1430 overScrollByCompat(x - oldX, y - oldY, oldX, oldY, 0, range, 1431 0, 0, false); 1432 1433 if (canOverscroll) { 1434 ensureGlows(); 1435 if (y <= 0 && oldY > 0) { 1436 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1437 } else if (y >= range && oldY < range) { 1438 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1439 } 1440 } 1441 } 1442 } 1443 } 1444 1445 /** 1446 * Scrolls the view to the given child. 1447 * 1448 * @param child the View to scroll to 1449 */ 1450 private void scrollToChild(View child) { 1451 child.getDrawingRect(mTempRect); 1452 1453 /* Offset from child's local coordinates to ScrollView coordinates */ 1454 offsetDescendantRectToMyCoords(child, mTempRect); 1455 1456 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1457 1458 if (scrollDelta != 0) { 1459 scrollBy(0, scrollDelta); 1460 } 1461 } 1462 1463 /** 1464 * If rect is off screen, scroll just enough to get it (or at least the 1465 * first screen size chunk of it) on screen. 1466 * 1467 * @param rect The rectangle. 1468 * @param immediate True to scroll immediately without animation 1469 * @return true if scrolling was performed 1470 */ 1471 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1472 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1473 final boolean scroll = delta != 0; 1474 if (scroll) { 1475 if (immediate) { 1476 scrollBy(0, delta); 1477 } else { 1478 smoothScrollBy(0, delta); 1479 } 1480 } 1481 return scroll; 1482 } 1483 1484 /** 1485 * Compute the amount to scroll in the Y direction in order to get 1486 * a rectangle completely on the screen (or, if taller than the screen, 1487 * at least the first screen size chunk of it). 1488 * 1489 * @param rect The rect. 1490 * @return The scroll delta. 1491 */ 1492 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1493 if (getChildCount() == 0) return 0; 1494 1495 int height = getHeight(); 1496 int screenTop = getScrollY(); 1497 int screenBottom = screenTop + height; 1498 1499 int fadingEdge = getVerticalFadingEdgeLength(); 1500 1501 // leave room for top fading edge as long as rect isn't at very top 1502 if (rect.top > 0) { 1503 screenTop += fadingEdge; 1504 } 1505 1506 // leave room for bottom fading edge as long as rect isn't at very bottom 1507 if (rect.bottom < getChildAt(0).getHeight()) { 1508 screenBottom -= fadingEdge; 1509 } 1510 1511 int scrollYDelta = 0; 1512 1513 if (rect.bottom > screenBottom && rect.top > screenTop) { 1514 // need to move down to get it in view: move down just enough so 1515 // that the entire rectangle is in view (or at least the first 1516 // screen size chunk). 1517 1518 if (rect.height() > height) { 1519 // just enough to get screen size chunk on 1520 scrollYDelta += (rect.top - screenTop); 1521 } else { 1522 // get entire rect at bottom of screen 1523 scrollYDelta += (rect.bottom - screenBottom); 1524 } 1525 1526 // make sure we aren't scrolling beyond the end of our content 1527 int bottom = getChildAt(0).getBottom(); 1528 int distanceToBottom = bottom - screenBottom; 1529 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1530 1531 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1532 // need to move up to get it in view: move up just enough so that 1533 // entire rectangle is in view (or at least the first screen 1534 // size chunk of it). 1535 1536 if (rect.height() > height) { 1537 // screen size chunk 1538 scrollYDelta -= (screenBottom - rect.bottom); 1539 } else { 1540 // entire rect at top 1541 scrollYDelta -= (screenTop - rect.top); 1542 } 1543 1544 // make sure we aren't scrolling any further than the top our content 1545 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1546 } 1547 return scrollYDelta; 1548 } 1549 1550 @Override 1551 public void requestChildFocus(View child, View focused) { 1552 if (!mIsLayoutDirty) { 1553 scrollToChild(focused); 1554 } else { 1555 // The child may not be laid out yet, we can't compute the scroll yet 1556 mChildToScrollTo = focused; 1557 } 1558 super.requestChildFocus(child, focused); 1559 } 1560 1561 1562 /** 1563 * When looking for focus in children of a scroll view, need to be a little 1564 * more careful not to give focus to something that is scrolled off screen. 1565 * 1566 * This is more expensive than the default {@link android.view.ViewGroup} 1567 * implementation, otherwise this behavior might have been made the default. 1568 */ 1569 @Override 1570 protected boolean onRequestFocusInDescendants(int direction, 1571 Rect previouslyFocusedRect) { 1572 1573 // convert from forward / backward notation to up / down / left / right 1574 // (ugh). 1575 if (direction == View.FOCUS_FORWARD) { 1576 direction = View.FOCUS_DOWN; 1577 } else if (direction == View.FOCUS_BACKWARD) { 1578 direction = View.FOCUS_UP; 1579 } 1580 1581 final View nextFocus = previouslyFocusedRect == null ? 1582 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1583 FocusFinder.getInstance().findNextFocusFromRect(this, 1584 previouslyFocusedRect, direction); 1585 1586 if (nextFocus == null) { 1587 return false; 1588 } 1589 1590 if (isOffScreen(nextFocus)) { 1591 return false; 1592 } 1593 1594 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1595 } 1596 1597 @Override 1598 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1599 boolean immediate) { 1600 // offset into coordinate space of this scroll view 1601 rectangle.offset(child.getLeft() - child.getScrollX(), 1602 child.getTop() - child.getScrollY()); 1603 1604 return scrollToChildRect(rectangle, immediate); 1605 } 1606 1607 @Override 1608 public void requestLayout() { 1609 mIsLayoutDirty = true; 1610 super.requestLayout(); 1611 } 1612 1613 @Override 1614 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1615 super.onLayout(changed, l, t, r, b); 1616 mIsLayoutDirty = false; 1617 // Give a child focus if it needs it 1618 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1619 scrollToChild(mChildToScrollTo); 1620 } 1621 mChildToScrollTo = null; 1622 1623 if (!mIsLaidOut) { 1624 if (mSavedState != null) { 1625 scrollTo(getScrollX(), mSavedState.scrollPosition); 1626 mSavedState = null; 1627 } // mScrollY default value is "0" 1628 1629 final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; 1630 final int scrollRange = Math.max(0, 1631 childHeight - (b - t - getPaddingBottom() - getPaddingTop())); 1632 1633 // Don't forget to clamp 1634 if (getScrollY() > scrollRange) { 1635 scrollTo(getScrollX(), scrollRange); 1636 } else if (getScrollY() < 0) { 1637 scrollTo(getScrollX(), 0); 1638 } 1639 } 1640 1641 // Calling this with the present values causes it to re-claim them 1642 scrollTo(getScrollX(), getScrollY()); 1643 mIsLaidOut = true; 1644 } 1645 1646 @Override 1647 public void onAttachedToWindow() { 1648 super.onAttachedToWindow(); 1649 1650 mIsLaidOut = false; 1651 } 1652 1653 @Override 1654 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1655 super.onSizeChanged(w, h, oldw, oldh); 1656 1657 View currentFocused = findFocus(); 1658 if (null == currentFocused || this == currentFocused) 1659 return; 1660 1661 // If the currently-focused view was visible on the screen when the 1662 // screen was at the old height, then scroll the screen to make that 1663 // view visible with the new screen height. 1664 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1665 currentFocused.getDrawingRect(mTempRect); 1666 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1667 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1668 doScrollY(scrollDelta); 1669 } 1670 } 1671 1672 /** 1673 * Return true if child is a descendant of parent, (or equal to the parent). 1674 */ 1675 private static boolean isViewDescendantOf(View child, View parent) { 1676 if (child == parent) { 1677 return true; 1678 } 1679 1680 final ViewParent theParent = child.getParent(); 1681 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1682 } 1683 1684 /** 1685 * Fling the scroll view 1686 * 1687 * @param velocityY The initial velocity in the Y direction. Positive 1688 * numbers mean that the finger/cursor is moving down the screen, 1689 * which means we want to scroll towards the top. 1690 */ 1691 public void fling(int velocityY) { 1692 if (getChildCount() > 0) { 1693 int height = getHeight() - getPaddingBottom() - getPaddingTop(); 1694 int bottom = getChildAt(0).getHeight(); 1695 1696 mScroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0, 1697 Math.max(0, bottom - height), 0, height/2); 1698 1699 ViewCompat.postInvalidateOnAnimation(this); 1700 } 1701 } 1702 1703 private void flingWithNestedDispatch(int velocityY) { 1704 final int scrollY = getScrollY(); 1705 final boolean canFling = (scrollY > 0 || velocityY > 0) && 1706 (scrollY < getScrollRange() || velocityY < 0); 1707 if (!dispatchNestedPreFling(0, velocityY)) { 1708 dispatchNestedFling(0, velocityY, canFling); 1709 if (canFling) { 1710 fling(velocityY); 1711 } 1712 } 1713 } 1714 1715 private void endDrag() { 1716 mIsBeingDragged = false; 1717 1718 recycleVelocityTracker(); 1719 stopNestedScroll(); 1720 1721 if (mEdgeGlowTop != null) { 1722 mEdgeGlowTop.onRelease(); 1723 mEdgeGlowBottom.onRelease(); 1724 } 1725 } 1726 1727 /** 1728 * {@inheritDoc} 1729 * 1730 * <p>This version also clamps the scrolling to the bounds of our child. 1731 */ 1732 @Override 1733 public void scrollTo(int x, int y) { 1734 // we rely on the fact the View.scrollBy calls scrollTo. 1735 if (getChildCount() > 0) { 1736 View child = getChildAt(0); 1737 x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); 1738 y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); 1739 if (x != getScrollX() || y != getScrollY()) { 1740 super.scrollTo(x, y); 1741 } 1742 } 1743 } 1744 1745 private void ensureGlows() { 1746 if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) { 1747 if (mEdgeGlowTop == null) { 1748 Context context = getContext(); 1749 mEdgeGlowTop = new EdgeEffectCompat(context); 1750 mEdgeGlowBottom = new EdgeEffectCompat(context); 1751 } 1752 } else { 1753 mEdgeGlowTop = null; 1754 mEdgeGlowBottom = null; 1755 } 1756 } 1757 1758 @Override 1759 public void draw(Canvas canvas) { 1760 super.draw(canvas); 1761 if (mEdgeGlowTop != null) { 1762 final int scrollY = getScrollY(); 1763 if (!mEdgeGlowTop.isFinished()) { 1764 final int restoreCount = canvas.save(); 1765 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1766 1767 canvas.translate(getPaddingLeft(), Math.min(0, scrollY)); 1768 mEdgeGlowTop.setSize(width, getHeight()); 1769 if (mEdgeGlowTop.draw(canvas)) { 1770 ViewCompat.postInvalidateOnAnimation(this); 1771 } 1772 canvas.restoreToCount(restoreCount); 1773 } 1774 if (!mEdgeGlowBottom.isFinished()) { 1775 final int restoreCount = canvas.save(); 1776 final int width = getWidth() - getPaddingLeft() - getPaddingRight(); 1777 final int height = getHeight(); 1778 1779 canvas.translate(-width + getPaddingLeft(), 1780 Math.max(getScrollRange(), scrollY) + height); 1781 canvas.rotate(180, width, 0); 1782 mEdgeGlowBottom.setSize(width, height); 1783 if (mEdgeGlowBottom.draw(canvas)) { 1784 ViewCompat.postInvalidateOnAnimation(this); 1785 } 1786 canvas.restoreToCount(restoreCount); 1787 } 1788 } 1789 } 1790 1791 private static int clamp(int n, int my, int child) { 1792 if (my >= child || n < 0) { 1793 /* my >= child is this case: 1794 * |--------------- me ---------------| 1795 * |------ child ------| 1796 * or 1797 * |--------------- me ---------------| 1798 * |------ child ------| 1799 * or 1800 * |--------------- me ---------------| 1801 * |------ child ------| 1802 * 1803 * n < 0 is this case: 1804 * |------ me ------| 1805 * |-------- child --------| 1806 * |-- mScrollX --| 1807 */ 1808 return 0; 1809 } 1810 if ((my+n) > child) { 1811 /* this case: 1812 * |------ me ------| 1813 * |------ child ------| 1814 * |-- mScrollX --| 1815 */ 1816 return child-my; 1817 } 1818 return n; 1819 } 1820 1821 @Override 1822 protected void onRestoreInstanceState(Parcelable state) { 1823 if (!(state instanceof SavedState)) { 1824 super.onRestoreInstanceState(state); 1825 return; 1826 } 1827 1828 SavedState ss = (SavedState) state; 1829 super.onRestoreInstanceState(ss.getSuperState()); 1830 mSavedState = ss; 1831 requestLayout(); 1832 } 1833 1834 @Override 1835 protected Parcelable onSaveInstanceState() { 1836 Parcelable superState = super.onSaveInstanceState(); 1837 SavedState ss = new SavedState(superState); 1838 ss.scrollPosition = getScrollY(); 1839 return ss; 1840 } 1841 1842 static class SavedState extends BaseSavedState { 1843 public int scrollPosition; 1844 1845 SavedState(Parcelable superState) { 1846 super(superState); 1847 } 1848 1849 public SavedState(Parcel source) { 1850 super(source); 1851 scrollPosition = source.readInt(); 1852 } 1853 1854 @Override 1855 public void writeToParcel(Parcel dest, int flags) { 1856 super.writeToParcel(dest, flags); 1857 dest.writeInt(scrollPosition); 1858 } 1859 1860 @Override 1861 public String toString() { 1862 return "HorizontalScrollView.SavedState{" 1863 + Integer.toHexString(System.identityHashCode(this)) 1864 + " scrollPosition=" + scrollPosition + "}"; 1865 } 1866 1867 public static final Parcelable.Creator<SavedState> CREATOR 1868 = new Parcelable.Creator<SavedState>() { 1869 @Override 1870 public SavedState createFromParcel(Parcel in) { 1871 return new SavedState(in); 1872 } 1873 1874 @Override 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