1/* 2 * Copyright (C) 2006 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 17package com.android.browser.view; 18 19import android.content.Context; 20import android.content.res.TypedArray; 21import android.graphics.PointF; 22import android.graphics.Rect; 23import android.os.StrictMode; 24import android.util.AttributeSet; 25import android.view.FocusFinder; 26import android.view.InputDevice; 27import android.view.KeyEvent; 28import android.view.MotionEvent; 29import android.view.VelocityTracker; 30import android.view.View; 31import android.view.ViewConfiguration; 32import android.view.ViewDebug; 33import android.view.ViewGroup; 34import android.view.ViewParent; 35import android.view.accessibility.AccessibilityEvent; 36import android.view.accessibility.AccessibilityNodeInfo; 37import android.view.animation.AnimationUtils; 38import android.widget.FrameLayout; 39import android.widget.LinearLayout; 40import android.widget.OverScroller; 41import android.widget.TextView; 42 43import com.android.internal.R; 44 45import java.util.List; 46 47/** 48 * Layout container for a view hierarchy that can be scrolled by the user, 49 * allowing it to be larger than the physical display. A ScrollView 50 * is a {@link FrameLayout}, meaning you should place one child in it 51 * containing the entire contents to scroll; this child may itself be a layout 52 * manager with a complex hierarchy of objects. A child that is often used 53 * is a {@link LinearLayout} in a vertical orientation, presenting a vertical 54 * array of top-level items that the user can scroll through. 55 * 56 * <p>The {@link TextView} class also 57 * takes care of its own scrolling, so does not require a ScrollView, but 58 * using the two together is possible to achieve the effect of a text view 59 * within a larger container. 60 * 61 * <p>ScrollView only supports vertical scrolling. 62 * 63 * @attr ref android.R.styleable#ScrollView_fillViewport 64 */ 65public class ScrollerView extends FrameLayout { 66 static final int ANIMATED_SCROLL_GAP = 250; 67 68 static final float MAX_SCROLL_FACTOR = 0.5f; 69 70 private long mLastScroll; 71 72 private final Rect mTempRect = new Rect(); 73 protected OverScroller mScroller; 74 75 /** 76 * Position of the last motion event. 77 */ 78 private float mLastMotionY; 79 80 /** 81 * True when the layout has changed but the traversal has not come through yet. 82 * Ideally the view hierarchy would keep track of this for us. 83 */ 84 private boolean mIsLayoutDirty = true; 85 86 /** 87 * The child to give focus to in the event that a child has requested focus while the 88 * layout is dirty. This prevents the scroll from being wrong if the child has not been 89 * laid out before requesting focus. 90 */ 91 protected View mChildToScrollTo = null; 92 93 /** 94 * True if the user is currently dragging this ScrollView around. This is 95 * not the same as 'is being flinged', which can be checked by 96 * mScroller.isFinished() (flinging begins when the user lifts his finger). 97 */ 98 protected boolean mIsBeingDragged = false; 99 100 /** 101 * Determines speed during touch scrolling 102 */ 103 private VelocityTracker mVelocityTracker; 104 105 /** 106 * When set to true, the scroll view measure its child to make it fill the currently 107 * visible area. 108 */ 109 @ViewDebug.ExportedProperty(category = "layout") 110 private boolean mFillViewport; 111 112 /** 113 * Whether arrow scrolling is animated. 114 */ 115 private boolean mSmoothScrollingEnabled = true; 116 117 private int mTouchSlop; 118 protected int mMinimumVelocity; 119 private int mMaximumVelocity; 120 121 private int mOverscrollDistance; 122 private int mOverflingDistance; 123 124 /** 125 * ID of the active pointer. This is used to retain consistency during 126 * drags/flings if multiple pointers are used. 127 */ 128 private int mActivePointerId = INVALID_POINTER; 129 130 /** 131 * The StrictMode "critical time span" objects to catch animation 132 * stutters. Non-null when a time-sensitive animation is 133 * in-flight. Must call finish() on them when done animating. 134 * These are no-ops on user builds. 135 */ 136 private StrictMode.Span mScrollStrictSpan = null; // aka "drag" 137 private StrictMode.Span mFlingStrictSpan = null; 138 139 /** 140 * Sentinel value for no current active pointer. 141 * Used by {@link #mActivePointerId}. 142 */ 143 private static final int INVALID_POINTER = -1; 144 145 /** 146 * orientation of the scrollview 147 */ 148 protected boolean mHorizontal; 149 150 protected boolean mIsOrthoDragged; 151 private float mLastOrthoCoord; 152 private View mDownView; 153 private PointF mDownCoords; 154 155 156 public ScrollerView(Context context) { 157 this(context, null); 158 } 159 160 public ScrollerView(Context context, AttributeSet attrs) { 161 this(context, attrs, com.android.internal.R.attr.scrollViewStyle); 162 } 163 164 public ScrollerView(Context context, AttributeSet attrs, int defStyle) { 165 super(context, attrs, defStyle); 166 initScrollView(); 167 168 TypedArray a = 169 context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ScrollView, defStyle, 0); 170 171 setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false)); 172 173 a.recycle(); 174 } 175 176 private void initScrollView() { 177 mScroller = new OverScroller(getContext()); 178 setFocusable(true); 179 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 180 setWillNotDraw(false); 181 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 182 mTouchSlop = configuration.getScaledTouchSlop(); 183 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 184 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 185 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 186 mOverflingDistance = configuration.getScaledOverflingDistance(); 187 mDownCoords = new PointF(); 188 } 189 190 public void setOrientation(int orientation) { 191 mHorizontal = (orientation == LinearLayout.HORIZONTAL); 192 requestLayout(); 193 } 194 195 @Override 196 public boolean shouldDelayChildPressedState() { 197 return true; 198 } 199 200 @Override 201 protected float getTopFadingEdgeStrength() { 202 if (getChildCount() == 0) { 203 return 0.0f; 204 } 205 if (mHorizontal) { 206 final int length = getHorizontalFadingEdgeLength(); 207 if (mScrollX < length) { 208 return mScrollX / (float) length; 209 } 210 } else { 211 final int length = getVerticalFadingEdgeLength(); 212 if (mScrollY < length) { 213 return mScrollY / (float) length; 214 } 215 } 216 return 1.0f; 217 } 218 219 @Override 220 protected float getBottomFadingEdgeStrength() { 221 if (getChildCount() == 0) { 222 return 0.0f; 223 } 224 if (mHorizontal) { 225 final int length = getHorizontalFadingEdgeLength(); 226 final int bottomEdge = getWidth() - mPaddingRight; 227 final int span = getChildAt(0).getRight() - mScrollX - bottomEdge; 228 if (span < length) { 229 return span / (float) length; 230 } 231 } else { 232 final int length = getVerticalFadingEdgeLength(); 233 final int bottomEdge = getHeight() - mPaddingBottom; 234 final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge; 235 if (span < length) { 236 return span / (float) length; 237 } 238 } 239 return 1.0f; 240 } 241 242 /** 243 * @return The maximum amount this scroll view will scroll in response to 244 * an arrow event. 245 */ 246 public int getMaxScrollAmount() { 247 return (int) (MAX_SCROLL_FACTOR * (mHorizontal 248 ? (mRight - mLeft) : (mBottom - mTop))); 249 } 250 251 252 @Override 253 public void addView(View child) { 254 if (getChildCount() > 0) { 255 throw new IllegalStateException("ScrollView can host only one direct child"); 256 } 257 258 super.addView(child); 259 } 260 261 @Override 262 public void addView(View child, int index) { 263 if (getChildCount() > 0) { 264 throw new IllegalStateException("ScrollView can host only one direct child"); 265 } 266 267 super.addView(child, index); 268 } 269 270 @Override 271 public void addView(View child, ViewGroup.LayoutParams params) { 272 if (getChildCount() > 0) { 273 throw new IllegalStateException("ScrollView can host only one direct child"); 274 } 275 276 super.addView(child, params); 277 } 278 279 @Override 280 public void addView(View child, int index, ViewGroup.LayoutParams params) { 281 if (getChildCount() > 0) { 282 throw new IllegalStateException("ScrollView can host only one direct child"); 283 } 284 285 super.addView(child, index, params); 286 } 287 288 /** 289 * @return Returns true this ScrollView can be scrolled 290 */ 291 private boolean canScroll() { 292 View child = getChildAt(0); 293 if (child != null) { 294 if (mHorizontal) { 295 return getWidth() < child.getWidth() + mPaddingLeft + mPaddingRight; 296 } else { 297 return getHeight() < child.getHeight() + mPaddingTop + mPaddingBottom; 298 } 299 } 300 return false; 301 } 302 303 /** 304 * Indicates whether this ScrollView's content is stretched to fill the viewport. 305 * 306 * @return True if the content fills the viewport, false otherwise. 307 * 308 * @attr ref android.R.styleable#ScrollView_fillViewport 309 */ 310 public boolean isFillViewport() { 311 return mFillViewport; 312 } 313 314 /** 315 * Indicates this ScrollView whether it should stretch its content height to fill 316 * the viewport or not. 317 * 318 * @param fillViewport True to stretch the content's height to the viewport's 319 * boundaries, false otherwise. 320 * 321 * @attr ref android.R.styleable#ScrollView_fillViewport 322 */ 323 public void setFillViewport(boolean fillViewport) { 324 if (fillViewport != mFillViewport) { 325 mFillViewport = fillViewport; 326 requestLayout(); 327 } 328 } 329 330 /** 331 * @return Whether arrow scrolling will animate its transition. 332 */ 333 public boolean isSmoothScrollingEnabled() { 334 return mSmoothScrollingEnabled; 335 } 336 337 /** 338 * Set whether arrow scrolling will animate its transition. 339 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 340 */ 341 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 342 mSmoothScrollingEnabled = smoothScrollingEnabled; 343 } 344 345 @Override 346 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 347 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 348 349 if (!mFillViewport) { 350 return; 351 } 352 353 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 354 if (heightMode == MeasureSpec.UNSPECIFIED) { 355 return; 356 } 357 358 if (getChildCount() > 0) { 359 final View child = getChildAt(0); 360 if (mHorizontal) { 361 int width = getMeasuredWidth(); 362 if (child.getMeasuredWidth() < width) { 363 final FrameLayout.LayoutParams lp = (LayoutParams) child 364 .getLayoutParams(); 365 366 int childHeightMeasureSpec = getChildMeasureSpec( 367 heightMeasureSpec, mPaddingTop + mPaddingBottom, 368 lp.height); 369 width -= mPaddingLeft; 370 width -= mPaddingRight; 371 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 372 width, MeasureSpec.EXACTLY); 373 374 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 375 } 376 } else { 377 int height = getMeasuredHeight(); 378 if (child.getMeasuredHeight() < height) { 379 final FrameLayout.LayoutParams lp = (LayoutParams) child 380 .getLayoutParams(); 381 382 int childWidthMeasureSpec = getChildMeasureSpec( 383 widthMeasureSpec, mPaddingLeft + mPaddingRight, 384 lp.width); 385 height -= mPaddingTop; 386 height -= mPaddingBottom; 387 int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 388 height, MeasureSpec.EXACTLY); 389 390 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 391 } 392 } 393 } 394 } 395 396 @Override 397 public boolean dispatchKeyEvent(KeyEvent event) { 398 // Let the focused view and/or our descendants get the key first 399 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 400 } 401 402 /** 403 * You can call this function yourself to have the scroll view perform 404 * scrolling from a key event, just as if the event had been dispatched to 405 * it by the view hierarchy. 406 * 407 * @param event The key event to execute. 408 * @return Return true if the event was handled, else false. 409 */ 410 public boolean executeKeyEvent(KeyEvent event) { 411 mTempRect.setEmpty(); 412 413 if (!canScroll()) { 414 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 415 View currentFocused = findFocus(); 416 if (currentFocused == this) currentFocused = null; 417 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 418 currentFocused, View.FOCUS_DOWN); 419 return nextFocused != null 420 && nextFocused != this 421 && nextFocused.requestFocus(View.FOCUS_DOWN); 422 } 423 return false; 424 } 425 426 boolean handled = false; 427 if (event.getAction() == KeyEvent.ACTION_DOWN) { 428 switch (event.getKeyCode()) { 429 case KeyEvent.KEYCODE_DPAD_UP: 430 if (!event.isAltPressed()) { 431 handled = arrowScroll(View.FOCUS_UP); 432 } else { 433 handled = fullScroll(View.FOCUS_UP); 434 } 435 break; 436 case KeyEvent.KEYCODE_DPAD_DOWN: 437 if (!event.isAltPressed()) { 438 handled = arrowScroll(View.FOCUS_DOWN); 439 } else { 440 handled = fullScroll(View.FOCUS_DOWN); 441 } 442 break; 443 case KeyEvent.KEYCODE_SPACE: 444 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 445 break; 446 } 447 } 448 449 return handled; 450 } 451 452 private boolean inChild(int x, int y) { 453 if (getChildCount() > 0) { 454 final int scrollY = mScrollY; 455 final View child = getChildAt(0); 456 return !(y < child.getTop() - scrollY 457 || y >= child.getBottom() - scrollY 458 || x < child.getLeft() 459 || x >= child.getRight()); 460 } 461 return false; 462 } 463 464 private void initOrResetVelocityTracker() { 465 if (mVelocityTracker == null) { 466 mVelocityTracker = VelocityTracker.obtain(); 467 } else { 468 mVelocityTracker.clear(); 469 } 470 } 471 472 private void initVelocityTrackerIfNotExists() { 473 if (mVelocityTracker == null) { 474 mVelocityTracker = VelocityTracker.obtain(); 475 } 476 } 477 478 private void recycleVelocityTracker() { 479 if (mVelocityTracker != null) { 480 mVelocityTracker.recycle(); 481 mVelocityTracker = null; 482 } 483 } 484 485 @Override 486 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 487 if (disallowIntercept) { 488 recycleVelocityTracker(); 489 } 490 super.requestDisallowInterceptTouchEvent(disallowIntercept); 491 } 492 493 @Override 494 public boolean onInterceptTouchEvent(MotionEvent ev) { 495 /* 496 * This method JUST determines whether we want to intercept the motion. 497 * If we return true, onMotionEvent will be called and we do the actual 498 * scrolling there. 499 */ 500 501 /* 502 * Shortcut the most recurring case: the user is in the dragging state 503 * and he is moving his finger. We want to intercept this motion. 504 */ 505 final int action = ev.getAction(); 506 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 507 return true; 508 } 509 if ((action == MotionEvent.ACTION_MOVE) && (mIsOrthoDragged)) { 510 return true; 511 } 512 switch (action & MotionEvent.ACTION_MASK) { 513 case MotionEvent.ACTION_MOVE: { 514 /* 515 * mIsBeingDragged == false, otherwise the shortcut would have 516 * caught it. Check whether the user has moved far enough from his 517 * original down touch. 518 */ 519 520 /* 521 * Locally do absolute value. mLastMotionY is set to the y value of 522 * the down event. 523 */ 524 final int activePointerId = mActivePointerId; 525 if (activePointerId == INVALID_POINTER) { 526 // If we don't have a valid id, the touch down wasn't on 527 // content. 528 break; 529 } 530 531 final int pointerIndex = ev.findPointerIndex(activePointerId); 532 final float y = mHorizontal ? ev.getX(pointerIndex) : ev 533 .getY(pointerIndex); 534 final int yDiff = (int) Math.abs(y - mLastMotionY); 535 if (yDiff > mTouchSlop) { 536 mIsBeingDragged = true; 537 mLastMotionY = y; 538 initVelocityTrackerIfNotExists(); 539 mVelocityTracker.addMovement(ev); 540 if (mScrollStrictSpan == null) { 541 mScrollStrictSpan = StrictMode 542 .enterCriticalSpan("ScrollView-scroll"); 543 } 544 } else { 545 final float ocoord = mHorizontal ? ev.getY(pointerIndex) : ev 546 .getX(pointerIndex); 547 if (Math.abs(ocoord - mLastOrthoCoord) > mTouchSlop) { 548 mIsOrthoDragged = true; 549 mLastOrthoCoord = ocoord; 550 initVelocityTrackerIfNotExists(); 551 mVelocityTracker.addMovement(ev); 552 } 553 } 554 break; 555 } 556 557 case MotionEvent.ACTION_DOWN: { 558 final float y = mHorizontal ? ev.getX() : ev.getY(); 559 mDownCoords.x = ev.getX(); 560 mDownCoords.y = ev.getY(); 561 if (!inChild((int) ev.getX(), (int) ev.getY())) { 562 mIsBeingDragged = false; 563 recycleVelocityTracker(); 564 break; 565 } 566 567 /* 568 * Remember location of down touch. ACTION_DOWN always refers to 569 * pointer index 0. 570 */ 571 mLastMotionY = y; 572 mActivePointerId = ev.getPointerId(0); 573 574 initOrResetVelocityTracker(); 575 mVelocityTracker.addMovement(ev); 576 /* 577 * If being flinged and user touches the screen, initiate drag; 578 * otherwise don't. mScroller.isFinished should be false when being 579 * flinged. 580 */ 581 mIsBeingDragged = !mScroller.isFinished(); 582 if (mIsBeingDragged && mScrollStrictSpan == null) { 583 mScrollStrictSpan = StrictMode 584 .enterCriticalSpan("ScrollView-scroll"); 585 } 586 mIsOrthoDragged = false; 587 final float ocoord = mHorizontal ? ev.getY() : ev.getX(); 588 mLastOrthoCoord = ocoord; 589 mDownView = findViewAt((int) ev.getX(), (int) ev.getY()); 590 break; 591 } 592 593 case MotionEvent.ACTION_CANCEL: 594 case MotionEvent.ACTION_UP: 595 /* Release the drag */ 596 mIsBeingDragged = false; 597 mIsOrthoDragged = false; 598 mActivePointerId = INVALID_POINTER; 599 recycleVelocityTracker(); 600 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, 601 getScrollRange())) { 602 invalidate(); 603 } 604 break; 605 case MotionEvent.ACTION_POINTER_UP: 606 onSecondaryPointerUp(ev); 607 break; 608 } 609 610 /* 611 * The only time we want to intercept motion events is if we are in the 612 * drag mode. 613 */ 614 return mIsBeingDragged || mIsOrthoDragged; 615 } 616 617 @Override 618 public boolean onTouchEvent(MotionEvent ev) { 619 initVelocityTrackerIfNotExists(); 620 mVelocityTracker.addMovement(ev); 621 622 final int action = ev.getAction(); 623 switch (action & MotionEvent.ACTION_MASK) { 624 case MotionEvent.ACTION_DOWN: { 625 mIsBeingDragged = getChildCount() != 0; 626 if (!mIsBeingDragged) { 627 return false; 628 } 629 630 /* 631 * If being flinged and user touches, stop the fling. isFinished 632 * will be false if being flinged. 633 */ 634 if (!mScroller.isFinished()) { 635 mScroller.abortAnimation(); 636 if (mFlingStrictSpan != null) { 637 mFlingStrictSpan.finish(); 638 mFlingStrictSpan = null; 639 } 640 } 641 642 // Remember where the motion event started 643 mLastMotionY = mHorizontal ? ev.getX() : ev.getY(); 644 mActivePointerId = ev.getPointerId(0); 645 break; 646 } 647 case MotionEvent.ACTION_MOVE: 648 if (mIsOrthoDragged) { 649 // Scroll to follow the motion event 650 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 651 final float x = ev.getX(activePointerIndex); 652 final float y = ev.getY(activePointerIndex); 653 if (isOrthoMove(x - mDownCoords.x, y - mDownCoords.y)) { 654 onOrthoDrag(mDownView, mHorizontal 655 ? y - mDownCoords.y 656 : x - mDownCoords.x); 657 } 658 } else if (mIsBeingDragged) { 659 // Scroll to follow the motion event 660 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 661 final float y = mHorizontal ? ev.getX(activePointerIndex) 662 : ev.getY(activePointerIndex); 663 final int deltaY = (int) (mLastMotionY - y); 664 mLastMotionY = y; 665 666 final int oldX = mScrollX; 667 final int oldY = mScrollY; 668 final int range = getScrollRange(); 669 if (mHorizontal) { 670 if (overScrollBy(deltaY, 0, mScrollX, 0, range, 0, 671 mOverscrollDistance, 0, true)) { 672 // Break our velocity if we hit a scroll barrier. 673 mVelocityTracker.clear(); 674 } 675 } else { 676 if (overScrollBy(0, deltaY, 0, mScrollY, 0, range, 677 0, mOverscrollDistance, true)) { 678 // Break our velocity if we hit a scroll barrier. 679 mVelocityTracker.clear(); 680 } 681 } 682 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 683 684 final int overscrollMode = getOverScrollMode(); 685 if (overscrollMode == OVER_SCROLL_ALWAYS || 686 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 687 final int pulledToY = mHorizontal ? oldX + deltaY : oldY + deltaY; 688 if (pulledToY < 0) { 689 onPull(pulledToY); 690 } else if (pulledToY > range) { 691 onPull(pulledToY - range); 692 } else { 693 onPull(0); 694 } 695 } 696 } 697 break; 698 case MotionEvent.ACTION_UP: 699 final VelocityTracker vtracker = mVelocityTracker; 700 vtracker.computeCurrentVelocity(1000, mMaximumVelocity); 701 if (isOrthoMove(vtracker.getXVelocity(mActivePointerId), 702 vtracker.getYVelocity(mActivePointerId)) 703 && mMinimumVelocity < Math.abs((mHorizontal ? vtracker.getYVelocity() 704 : vtracker.getXVelocity()))) { 705 onOrthoFling(mDownView, mHorizontal ? vtracker.getYVelocity() 706 : vtracker.getXVelocity()); 707 break; 708 } 709 if (mIsOrthoDragged) { 710 onOrthoDragFinished(mDownView); 711 mActivePointerId = INVALID_POINTER; 712 endDrag(); 713 } else if (mIsBeingDragged) { 714 final VelocityTracker velocityTracker = mVelocityTracker; 715 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 716 int initialVelocity = mHorizontal 717 ? (int) velocityTracker.getXVelocity(mActivePointerId) 718 : (int) velocityTracker.getYVelocity(mActivePointerId); 719 720 if (getChildCount() > 0) { 721 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 722 fling(-initialVelocity); 723 } else { 724 final int bottom = getScrollRange(); 725 if (mHorizontal) { 726 if (mScroller.springBack(mScrollX, mScrollY, 0, bottom, 0, 0)) { 727 invalidate(); 728 } 729 } else { 730 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, bottom)) { 731 invalidate(); 732 } 733 } 734 } 735 onPull(0); 736 } 737 738 mActivePointerId = INVALID_POINTER; 739 endDrag(); 740 } 741 break; 742 case MotionEvent.ACTION_CANCEL: 743 if (mIsOrthoDragged) { 744 onOrthoDragFinished(mDownView); 745 mActivePointerId = INVALID_POINTER; 746 endDrag(); 747 } else if (mIsBeingDragged && getChildCount() > 0) { 748 if (mHorizontal) { 749 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 750 invalidate(); 751 } 752 } else { 753 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 754 invalidate(); 755 } 756 } 757 mActivePointerId = INVALID_POINTER; 758 endDrag(); 759 } 760 break; 761 case MotionEvent.ACTION_POINTER_DOWN: { 762 final int index = ev.getActionIndex(); 763 final float y = mHorizontal ? ev.getX(index) : ev.getY(index); 764 mLastMotionY = y; 765 mLastOrthoCoord = mHorizontal ? ev.getY(index) : ev.getX(index); 766 mActivePointerId = ev.getPointerId(index); 767 break; 768 } 769 case MotionEvent.ACTION_POINTER_UP: 770 onSecondaryPointerUp(ev); 771 mLastMotionY = mHorizontal 772 ? ev.getX(ev.findPointerIndex(mActivePointerId)) 773 : ev.getY(ev.findPointerIndex(mActivePointerId)); 774 break; 775 } 776 return true; 777 } 778 779 protected View findViewAt(int x, int y) { 780 // subclass responsibility 781 return null; 782 } 783 784 protected void onPull(int delta) { 785 } 786 787 private void onSecondaryPointerUp(MotionEvent ev) { 788 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 789 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 790 final int pointerId = ev.getPointerId(pointerIndex); 791 if (pointerId == mActivePointerId) { 792 // This was our active pointer going up. Choose a new 793 // active pointer and adjust accordingly. 794 // TODO: Make this decision more intelligent. 795 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 796 mLastMotionY = mHorizontal ? ev.getX(newPointerIndex) : ev.getY(newPointerIndex); 797 mActivePointerId = ev.getPointerId(newPointerIndex); 798 if (mVelocityTracker != null) { 799 mVelocityTracker.clear(); 800 } 801 mLastOrthoCoord = mHorizontal ? ev.getY(newPointerIndex) 802 : ev.getX(newPointerIndex); 803 } 804 } 805 806 @Override 807 public boolean onGenericMotionEvent(MotionEvent event) { 808 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 809 switch (event.getAction()) { 810 case MotionEvent.ACTION_SCROLL: { 811 if (!mIsBeingDragged) { 812 if (mHorizontal) { 813 final float hscroll = event 814 .getAxisValue(MotionEvent.AXIS_HSCROLL); 815 if (hscroll != 0) { 816 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 817 final int range = getScrollRange(); 818 int oldScrollX = mScrollX; 819 int newScrollX = oldScrollX - delta; 820 if (newScrollX < 0) { 821 newScrollX = 0; 822 } else if (newScrollX > range) { 823 newScrollX = range; 824 } 825 if (newScrollX != oldScrollX) { 826 super.scrollTo(newScrollX, mScrollY); 827 return true; 828 } 829 } 830 } else { 831 final float vscroll = event 832 .getAxisValue(MotionEvent.AXIS_VSCROLL); 833 if (vscroll != 0) { 834 final int delta = (int) (vscroll * getVerticalScrollFactor()); 835 final int range = getScrollRange(); 836 int oldScrollY = mScrollY; 837 int newScrollY = oldScrollY - delta; 838 if (newScrollY < 0) { 839 newScrollY = 0; 840 } else if (newScrollY > range) { 841 newScrollY = range; 842 } 843 if (newScrollY != oldScrollY) { 844 super.scrollTo(mScrollX, newScrollY); 845 return true; 846 } 847 } 848 } 849 } 850 } 851 } 852 } 853 return super.onGenericMotionEvent(event); 854 } 855 856 protected void onOrthoDrag(View draggedView, float distance) { 857 } 858 859 protected void onOrthoDragFinished(View draggedView) { 860 } 861 862 protected void onOrthoFling(View draggedView, float velocity) { 863 } 864 865 @Override 866 protected void onOverScrolled(int scrollX, int scrollY, 867 boolean clampedX, boolean clampedY) { 868 // Treat animating scrolls differently; see #computeScroll() for why. 869 if (!mScroller.isFinished()) { 870 mScrollX = scrollX; 871 mScrollY = scrollY; 872 invalidateParentIfNeeded(); 873 if (mHorizontal && clampedX) { 874 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 875 } else if (!mHorizontal && clampedY) { 876 mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 877 } 878 } else { 879 super.scrollTo(scrollX, scrollY); 880 } 881 awakenScrollBars(); 882 } 883 884 @Override 885 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 886 super.onInitializeAccessibilityNodeInfo(info); 887 info.setScrollable(true); 888 } 889 890 @Override 891 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 892 super.onInitializeAccessibilityEvent(event); 893 event.setScrollable(true); 894 } 895 896 @Override 897 public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) { 898 // Do not append text content to scroll events they are fired frequently 899 // and the client has already received another event type with the text. 900 if (event.getEventType() != AccessibilityEvent.TYPE_VIEW_SCROLLED) { 901 super.dispatchPopulateAccessibilityEvent(event); 902 } 903 return false; 904 } 905 906 private int getScrollRange() { 907 int scrollRange = 0; 908 if (getChildCount() > 0) { 909 View child = getChildAt(0); 910 if (mHorizontal) { 911 scrollRange = Math.max(0, 912 child.getWidth() - (getWidth() - mPaddingRight - mPaddingLeft)); 913 } else { 914 scrollRange = Math.max(0, 915 child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop)); 916 } 917 } 918 return scrollRange; 919 } 920 921 /** 922 * <p> 923 * Finds the next focusable component that fits in this View's bounds 924 * (excluding fading edges) pretending that this View's top is located at 925 * the parameter top. 926 * </p> 927 * 928 * @param topFocus look for a candidate at the top of the bounds if topFocus is true, 929 * or at the bottom of the bounds if topFocus is false 930 * @param top the top offset of the bounds in which a focusable must be 931 * found (the fading edge is assumed to start at this position) 932 * @param preferredFocusable the View that has highest priority and will be 933 * returned if it is within my bounds (null is valid) 934 * @return the next focusable component in the bounds or null if none can be found 935 */ 936 private View findFocusableViewInMyBounds(final boolean topFocus, 937 final int top, View preferredFocusable) { 938 /* 939 * The fading edge's transparent side should be considered for focus 940 * since it's mostly visible, so we divide the actual fading edge length 941 * by 2. 942 */ 943 final int fadingEdgeLength = (mHorizontal 944 ? getHorizontalFadingEdgeLength() 945 : getVerticalFadingEdgeLength()) / 2; 946 final int topWithoutFadingEdge = top + fadingEdgeLength; 947 final int bottomWithoutFadingEdge = top + (mHorizontal ? getWidth() : getHeight()) - fadingEdgeLength; 948 949 if ((preferredFocusable != null) 950 && ((mHorizontal ? preferredFocusable.getLeft() : preferredFocusable.getTop()) 951 < bottomWithoutFadingEdge) 952 && ((mHorizontal ? preferredFocusable.getRight() : preferredFocusable.getBottom()) > topWithoutFadingEdge)) { 953 return preferredFocusable; 954 } 955 956 return findFocusableViewInBounds(topFocus, topWithoutFadingEdge, 957 bottomWithoutFadingEdge); 958 } 959 960 /** 961 * <p> 962 * Finds the next focusable component that fits in the specified bounds. 963 * </p> 964 * 965 * @param topFocus look for a candidate is the one at the top of the bounds 966 * if topFocus is true, or at the bottom of the bounds if topFocus is 967 * false 968 * @param top the top offset of the bounds in which a focusable must be 969 * found 970 * @param bottom the bottom offset of the bounds in which a focusable must 971 * be found 972 * @return the next focusable component in the bounds or null if none can 973 * be found 974 */ 975 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 976 977 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 978 View focusCandidate = null; 979 980 /* 981 * A fully contained focusable is one where its top is below the bound's 982 * top, and its bottom is above the bound's bottom. A partially 983 * contained focusable is one where some part of it is within the 984 * bounds, but it also has some part that is not within bounds. A fully contained 985 * focusable is preferred to a partially contained focusable. 986 */ 987 boolean foundFullyContainedFocusable = false; 988 989 int count = focusables.size(); 990 for (int i = 0; i < count; i++) { 991 View view = focusables.get(i); 992 int viewTop = mHorizontal ? view.getLeft() : view.getTop(); 993 int viewBottom = mHorizontal ? view.getRight() : view.getBottom(); 994 995 if (top < viewBottom && viewTop < bottom) { 996 /* 997 * the focusable is in the target area, it is a candidate for 998 * focusing 999 */ 1000 1001 final boolean viewIsFullyContained = (top < viewTop) && 1002 (viewBottom < bottom); 1003 1004 if (focusCandidate == null) { 1005 /* No candidate, take this one */ 1006 focusCandidate = view; 1007 foundFullyContainedFocusable = viewIsFullyContained; 1008 } else { 1009 final int ctop = mHorizontal ? focusCandidate.getLeft() : focusCandidate.getTop(); 1010 final int cbot = mHorizontal ? focusCandidate.getRight() : focusCandidate.getBottom(); 1011 final boolean viewIsCloserToBoundary = 1012 (topFocus && viewTop < ctop) || 1013 (!topFocus && viewBottom > cbot); 1014 1015 if (foundFullyContainedFocusable) { 1016 if (viewIsFullyContained && viewIsCloserToBoundary) { 1017 /* 1018 * We're dealing with only fully contained views, so 1019 * it has to be closer to the boundary to beat our 1020 * candidate 1021 */ 1022 focusCandidate = view; 1023 } 1024 } else { 1025 if (viewIsFullyContained) { 1026 /* Any fully contained view beats a partially contained view */ 1027 focusCandidate = view; 1028 foundFullyContainedFocusable = true; 1029 } else if (viewIsCloserToBoundary) { 1030 /* 1031 * Partially contained view beats another partially 1032 * contained view if it's closer 1033 */ 1034 focusCandidate = view; 1035 } 1036 } 1037 } 1038 } 1039 } 1040 1041 return focusCandidate; 1042 } 1043 1044 // i was here 1045 1046 /** 1047 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 1048 * method will scroll the view by one page up or down and give the focus 1049 * to the topmost/bottommost component in the new visible area. If no 1050 * component is a good candidate for focus, this scrollview reclaims the 1051 * focus.</p> 1052 * 1053 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1054 * to go one page up or 1055 * {@link android.view.View#FOCUS_DOWN} to go one page down 1056 * @return true if the key event is consumed by this method, false otherwise 1057 */ 1058 public boolean pageScroll(int direction) { 1059 boolean down = direction == View.FOCUS_DOWN; 1060 int height = getHeight(); 1061 1062 if (down) { 1063 mTempRect.top = getScrollY() + height; 1064 int count = getChildCount(); 1065 if (count > 0) { 1066 View view = getChildAt(count - 1); 1067 if (mTempRect.top + height > view.getBottom()) { 1068 mTempRect.top = view.getBottom() - height; 1069 } 1070 } 1071 } else { 1072 mTempRect.top = getScrollY() - height; 1073 if (mTempRect.top < 0) { 1074 mTempRect.top = 0; 1075 } 1076 } 1077 mTempRect.bottom = mTempRect.top + height; 1078 1079 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1080 } 1081 1082 /** 1083 * <p>Handles scrolling in response to a "home/end" shortcut press. This 1084 * method will scroll the view to the top or bottom and give the focus 1085 * to the topmost/bottommost component in the new visible area. If no 1086 * component is a good candidate for focus, this scrollview reclaims the 1087 * focus.</p> 1088 * 1089 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1090 * to go the top of the view or 1091 * {@link android.view.View#FOCUS_DOWN} to go the bottom 1092 * @return true if the key event is consumed by this method, false otherwise 1093 */ 1094 public boolean fullScroll(int direction) { 1095 boolean down = direction == View.FOCUS_DOWN; 1096 int height = getHeight(); 1097 1098 mTempRect.top = 0; 1099 mTempRect.bottom = height; 1100 1101 if (down) { 1102 int count = getChildCount(); 1103 if (count > 0) { 1104 View view = getChildAt(count - 1); 1105 mTempRect.bottom = view.getBottom() + mPaddingBottom; 1106 mTempRect.top = mTempRect.bottom - height; 1107 } 1108 } 1109 1110 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 1111 } 1112 1113 /** 1114 * <p>Scrolls the view to make the area defined by <code>top</code> and 1115 * <code>bottom</code> visible. This method attempts to give the focus 1116 * to a component visible in this area. If no component can be focused in 1117 * the new visible area, the focus is reclaimed by this ScrollView.</p> 1118 * 1119 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 1120 * to go upward, {@link android.view.View#FOCUS_DOWN} to downward 1121 * @param top the top offset of the new area to be made visible 1122 * @param bottom the bottom offset of the new area to be made visible 1123 * @return true if the key event is consumed by this method, false otherwise 1124 */ 1125 private boolean scrollAndFocus(int direction, int top, int bottom) { 1126 boolean handled = true; 1127 1128 int height = getHeight(); 1129 int containerTop = getScrollY(); 1130 int containerBottom = containerTop + height; 1131 boolean up = direction == View.FOCUS_UP; 1132 1133 View newFocused = findFocusableViewInBounds(up, top, bottom); 1134 if (newFocused == null) { 1135 newFocused = this; 1136 } 1137 1138 if (top >= containerTop && bottom <= containerBottom) { 1139 handled = false; 1140 } else { 1141 int delta = up ? (top - containerTop) : (bottom - containerBottom); 1142 doScrollY(delta); 1143 } 1144 1145 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1146 1147 return handled; 1148 } 1149 1150 /** 1151 * Handle scrolling in response to an up or down arrow click. 1152 * 1153 * @param direction The direction corresponding to the arrow key that was 1154 * pressed 1155 * @return True if we consumed the event, false otherwise 1156 */ 1157 public boolean arrowScroll(int direction) { 1158 1159 View currentFocused = findFocus(); 1160 if (currentFocused == this) currentFocused = null; 1161 1162 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1163 1164 final int maxJump = getMaxScrollAmount(); 1165 1166 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 1167 nextFocused.getDrawingRect(mTempRect); 1168 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1169 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1170 doScrollY(scrollDelta); 1171 nextFocused.requestFocus(direction); 1172 } else { 1173 // no new focus 1174 int scrollDelta = maxJump; 1175 1176 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 1177 scrollDelta = getScrollY(); 1178 } else if (direction == View.FOCUS_DOWN) { 1179 if (getChildCount() > 0) { 1180 int daBottom = getChildAt(0).getBottom(); 1181 int screenBottom = getScrollY() + getHeight() - mPaddingBottom; 1182 if (daBottom - screenBottom < maxJump) { 1183 scrollDelta = daBottom - screenBottom; 1184 } 1185 } 1186 } 1187 if (scrollDelta == 0) { 1188 return false; 1189 } 1190 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 1191 } 1192 1193 if (currentFocused != null && currentFocused.isFocused() 1194 && isOffScreen(currentFocused)) { 1195 // previously focused item still has focus and is off screen, give 1196 // it up (take it back to ourselves) 1197 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1198 // sure to 1199 // get it) 1200 final int descendantFocusability = getDescendantFocusability(); // save 1201 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1202 requestFocus(); 1203 setDescendantFocusability(descendantFocusability); // restore 1204 } 1205 return true; 1206 } 1207 1208 private boolean isOrthoMove(float moveX, float moveY) { 1209 return mHorizontal && Math.abs(moveY) > Math.abs(moveX) 1210 || !mHorizontal && Math.abs(moveX) > Math.abs(moveY); 1211 } 1212 1213 /** 1214 * @return whether the descendant of this scroll view is scrolled off 1215 * screen. 1216 */ 1217 private boolean isOffScreen(View descendant) { 1218 if (mHorizontal) { 1219 return !isWithinDeltaOfScreen(descendant, getWidth(), 0); 1220 } else { 1221 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 1222 } 1223 } 1224 1225 /** 1226 * @return whether the descendant of this scroll view is within delta 1227 * pixels of being on the screen. 1228 */ 1229 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 1230 descendant.getDrawingRect(mTempRect); 1231 offsetDescendantRectToMyCoords(descendant, mTempRect); 1232 if (mHorizontal) { 1233 return (mTempRect.right + delta) >= getScrollX() 1234 && (mTempRect.left - delta) <= (getScrollX() + height); 1235 } else { 1236 return (mTempRect.bottom + delta) >= getScrollY() 1237 && (mTempRect.top - delta) <= (getScrollY() + height); 1238 } 1239 } 1240 1241 /** 1242 * Smooth scroll by a Y delta 1243 * 1244 * @param delta the number of pixels to scroll by on the Y axis 1245 */ 1246 private void doScrollY(int delta) { 1247 if (delta != 0) { 1248 if (mSmoothScrollingEnabled) { 1249 if (mHorizontal) { 1250 smoothScrollBy(0, delta); 1251 } else { 1252 smoothScrollBy(delta, 0); 1253 } 1254 } else { 1255 if (mHorizontal) { 1256 scrollBy(0, delta); 1257 } else { 1258 scrollBy(delta, 0); 1259 } 1260 } 1261 } 1262 } 1263 1264 /** 1265 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1266 * 1267 * @param dx the number of pixels to scroll by on the X axis 1268 * @param dy the number of pixels to scroll by on the Y axis 1269 */ 1270 public final void smoothScrollBy(int dx, int dy) { 1271 if (getChildCount() == 0) { 1272 // Nothing to do. 1273 return; 1274 } 1275 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1276 if (duration > ANIMATED_SCROLL_GAP) { 1277 if (mHorizontal) { 1278 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1279 final int right = getChildAt(0).getWidth(); 1280 final int maxX = Math.max(0, right - width); 1281 final int scrollX = mScrollX; 1282 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1283 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1284 } else { 1285 final int height = getHeight() - mPaddingBottom - mPaddingTop; 1286 final int bottom = getChildAt(0).getHeight(); 1287 final int maxY = Math.max(0, bottom - height); 1288 final int scrollY = mScrollY; 1289 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 1290 mScroller.startScroll(mScrollX, scrollY, 0, dy); 1291 } 1292 invalidate(); 1293 } else { 1294 if (!mScroller.isFinished()) { 1295 mScroller.abortAnimation(); 1296 if (mFlingStrictSpan != null) { 1297 mFlingStrictSpan.finish(); 1298 mFlingStrictSpan = null; 1299 } 1300 } 1301 scrollBy(dx, dy); 1302 } 1303 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1304 } 1305 1306 /** 1307 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1308 * 1309 * @param x the position where to scroll on the X axis 1310 * @param y the position where to scroll on the Y axis 1311 */ 1312 public final void smoothScrollTo(int x, int y) { 1313 smoothScrollBy(x - mScrollX, y - mScrollY); 1314 } 1315 1316 /** 1317 * <p> 1318 * The scroll range of a scroll view is the overall height of all of its 1319 * children. 1320 * </p> 1321 */ 1322 @Override 1323 protected int computeVerticalScrollRange() { 1324 if (mHorizontal) { 1325 return super.computeVerticalScrollRange(); 1326 } 1327 final int count = getChildCount(); 1328 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1329 if (count == 0) { 1330 return contentHeight; 1331 } 1332 1333 int scrollRange = getChildAt(0).getBottom(); 1334 final int scrollY = mScrollY; 1335 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1336 if (scrollY < 0) { 1337 scrollRange -= scrollY; 1338 } else if (scrollY > overscrollBottom) { 1339 scrollRange += scrollY - overscrollBottom; 1340 } 1341 1342 return scrollRange; 1343 } 1344 1345 /** 1346 * <p> 1347 * The scroll range of a scroll view is the overall height of all of its 1348 * children. 1349 * </p> 1350 */ 1351 @Override 1352 protected int computeHorizontalScrollRange() { 1353 if (!mHorizontal) { 1354 return super.computeHorizontalScrollRange(); 1355 } 1356 final int count = getChildCount(); 1357 final int contentWidth = getWidth() - mPaddingRight - mPaddingLeft; 1358 if (count == 0) { 1359 return contentWidth; 1360 } 1361 1362 int scrollRange = getChildAt(0).getRight(); 1363 final int scrollX = mScrollX; 1364 final int overscrollBottom = Math.max(0, scrollRange - contentWidth); 1365 if (scrollX < 0) { 1366 scrollRange -= scrollX; 1367 } else if (scrollX > overscrollBottom) { 1368 scrollRange += scrollX - overscrollBottom; 1369 } 1370 1371 return scrollRange; 1372 } 1373 1374 @Override 1375 protected int computeVerticalScrollOffset() { 1376 return Math.max(0, super.computeVerticalScrollOffset()); 1377 } 1378 1379 @Override 1380 protected int computeHorizontalScrollOffset() { 1381 return Math.max(0, super.computeHorizontalScrollOffset()); 1382 } 1383 1384 @Override 1385 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1386 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1387 1388 int childWidthMeasureSpec; 1389 int childHeightMeasureSpec; 1390 1391 if (mHorizontal) { 1392 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1393 + mPaddingBottom, lp.height); 1394 1395 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1396 } else { 1397 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1398 + mPaddingRight, lp.width); 1399 1400 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1401 } 1402 1403 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1404 } 1405 1406 @Override 1407 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1408 int parentHeightMeasureSpec, int heightUsed) { 1409 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1410 1411 int childWidthMeasureSpec; 1412 int childHeightMeasureSpec; 1413 if (mHorizontal) { 1414 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1415 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1416 + heightUsed, lp.height); 1417 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1418 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1419 } else { 1420 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1421 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1422 + widthUsed, lp.width); 1423 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1424 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1425 } 1426 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1427 } 1428 1429 @Override 1430 public void computeScroll() { 1431 if (mScroller.computeScrollOffset()) { 1432 // This is called at drawing time by ViewGroup. We don't want to 1433 // re-show the scrollbars at this point, which scrollTo will do, 1434 // so we replicate most of scrollTo here. 1435 // 1436 // It's a little odd to call onScrollChanged from inside the drawing. 1437 // 1438 // It is, except when you remember that computeScroll() is used to 1439 // animate scrolling. So unless we want to defer the onScrollChanged() 1440 // until the end of the animated scrolling, we don't really have a 1441 // choice here. 1442 // 1443 // I agree. The alternative, which I think would be worse, is to post 1444 // something and tell the subclasses later. This is bad because there 1445 // will be a window where mScrollX/Y is different from what the app 1446 // thinks it is. 1447 // 1448 int oldX = mScrollX; 1449 int oldY = mScrollY; 1450 int x = mScroller.getCurrX(); 1451 int y = mScroller.getCurrY(); 1452 1453 if (oldX != x || oldY != y) { 1454 if (mHorizontal) { 1455 overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, 1456 mOverflingDistance, 0, false); 1457 } else { 1458 overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, getScrollRange(), 1459 0, mOverflingDistance, false); 1460 } 1461 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1462 } 1463 awakenScrollBars(); 1464 1465 // Keep on drawing until the animation has finished. 1466 postInvalidate(); 1467 } else { 1468 if (mFlingStrictSpan != null) { 1469 mFlingStrictSpan.finish(); 1470 mFlingStrictSpan = null; 1471 } 1472 } 1473 } 1474 1475 /** 1476 * Scrolls the view to the given child. 1477 * 1478 * @param child the View to scroll to 1479 */ 1480 private void scrollToChild(View child) { 1481 child.getDrawingRect(mTempRect); 1482 1483 /* Offset from child's local coordinates to ScrollView coordinates */ 1484 offsetDescendantRectToMyCoords(child, mTempRect); 1485 scrollToChildRect(mTempRect, true); 1486 } 1487 1488 /** 1489 * If rect is off screen, scroll just enough to get it (or at least the 1490 * first screen size chunk of it) on screen. 1491 * 1492 * @param rect The rectangle. 1493 * @param immediate True to scroll immediately without animation 1494 * @return true if scrolling was performed 1495 */ 1496 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1497 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1498 final boolean scroll = delta != 0; 1499 if (scroll) { 1500 if (immediate) { 1501 if (mHorizontal) { 1502 scrollBy(delta, 0); 1503 } else { 1504 scrollBy(0, delta); 1505 } 1506 } else { 1507 if (mHorizontal) { 1508 smoothScrollBy(delta, 0); 1509 } else { 1510 smoothScrollBy(0, delta); 1511 } 1512 } 1513 } 1514 return scroll; 1515 } 1516 1517 /** 1518 * Compute the amount to scroll in the Y direction in order to get 1519 * a rectangle completely on the screen (or, if taller than the screen, 1520 * at least the first screen size chunk of it). 1521 * 1522 * @param rect The rect. 1523 * @return The scroll delta. 1524 */ 1525 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1526 if (mHorizontal) { 1527 return computeScrollDeltaToGetChildRectOnScreenHorizontal(rect); 1528 } else { 1529 return computeScrollDeltaToGetChildRectOnScreenVertical(rect); 1530 } 1531 } 1532 1533 private int computeScrollDeltaToGetChildRectOnScreenVertical(Rect rect) { 1534 if (getChildCount() == 0) return 0; 1535 1536 int height = getHeight(); 1537 int screenTop = getScrollY(); 1538 int screenBottom = screenTop + height; 1539 1540 int fadingEdge = getVerticalFadingEdgeLength(); 1541 1542 // leave room for top fading edge as long as rect isn't at very top 1543 if (rect.top > 0) { 1544 screenTop += fadingEdge; 1545 } 1546 1547 // leave room for bottom fading edge as long as rect isn't at very bottom 1548 if (rect.bottom < getChildAt(0).getHeight()) { 1549 screenBottom -= fadingEdge; 1550 } 1551 1552 int scrollYDelta = 0; 1553 1554 if (rect.bottom > screenBottom && rect.top > screenTop) { 1555 // need to move down to get it in view: move down just enough so 1556 // that the entire rectangle is in view (or at least the first 1557 // screen size chunk). 1558 1559 if (rect.height() > height) { 1560 // just enough to get screen size chunk on 1561 scrollYDelta += (rect.top - screenTop); 1562 } else { 1563 // get entire rect at bottom of screen 1564 scrollYDelta += (rect.bottom - screenBottom); 1565 } 1566 1567 // make sure we aren't scrolling beyond the end of our content 1568 int bottom = getChildAt(0).getBottom(); 1569 int distanceToBottom = bottom - screenBottom; 1570 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1571 1572 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1573 // need to move up to get it in view: move up just enough so that 1574 // entire rectangle is in view (or at least the first screen 1575 // size chunk of it). 1576 1577 if (rect.height() > height) { 1578 // screen size chunk 1579 scrollYDelta -= (screenBottom - rect.bottom); 1580 } else { 1581 // entire rect at top 1582 scrollYDelta -= (screenTop - rect.top); 1583 } 1584 1585 // make sure we aren't scrolling any further than the top our content 1586 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1587 } 1588 return scrollYDelta; 1589 } 1590 1591 private int computeScrollDeltaToGetChildRectOnScreenHorizontal(Rect rect) { 1592 if (getChildCount() == 0) return 0; 1593 1594 int width = getWidth(); 1595 int screenLeft = getScrollX(); 1596 int screenRight = screenLeft + width; 1597 1598 int fadingEdge = getHorizontalFadingEdgeLength(); 1599 1600 // leave room for left fading edge as long as rect isn't at very left 1601 if (rect.left > 0) { 1602 screenLeft += fadingEdge; 1603 } 1604 1605 // leave room for right fading edge as long as rect isn't at very right 1606 if (rect.right < getChildAt(0).getWidth()) { 1607 screenRight -= fadingEdge; 1608 } 1609 1610 int scrollXDelta = 0; 1611 1612 if (rect.right > screenRight && rect.left > screenLeft) { 1613 // need to move right to get it in view: move right just enough so 1614 // that the entire rectangle is in view (or at least the first 1615 // screen size chunk). 1616 1617 if (rect.width() > width) { 1618 // just enough to get screen size chunk on 1619 scrollXDelta += (rect.left - screenLeft); 1620 } else { 1621 // get entire rect at right of screen 1622 scrollXDelta += (rect.right - screenRight); 1623 } 1624 1625 // make sure we aren't scrolling beyond the end of our content 1626 int right = getChildAt(0).getRight(); 1627 int distanceToRight = right - screenRight; 1628 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1629 1630 } else if (rect.left < screenLeft && rect.right < screenRight) { 1631 // need to move right to get it in view: move right just enough so that 1632 // entire rectangle is in view (or at least the first screen 1633 // size chunk of it). 1634 1635 if (rect.width() > width) { 1636 // screen size chunk 1637 scrollXDelta -= (screenRight - rect.right); 1638 } else { 1639 // entire rect at left 1640 scrollXDelta -= (screenLeft - rect.left); 1641 } 1642 1643 // make sure we aren't scrolling any further than the left our content 1644 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1645 } 1646 return scrollXDelta; 1647 } 1648 1649 1650 @Override 1651 public void requestChildFocus(View child, View focused) { 1652 if (!mIsLayoutDirty) { 1653 scrollToChild(focused); 1654 } else { 1655 // The child may not be laid out yet, we can't compute the scroll yet 1656 mChildToScrollTo = focused; 1657 } 1658 super.requestChildFocus(child, focused); 1659 } 1660 1661 1662 /** 1663 * When looking for focus in children of a scroll view, need to be a little 1664 * more careful not to give focus to something that is scrolled off screen. 1665 * 1666 * This is more expensive than the default {@link android.view.ViewGroup} 1667 * implementation, otherwise this behavior might have been made the default. 1668 */ 1669 @Override 1670 protected boolean onRequestFocusInDescendants(int direction, 1671 Rect previouslyFocusedRect) { 1672 1673 // convert from forward / backward notation to up / down / left / right 1674 // (ugh). 1675 if (mHorizontal) { 1676 if (direction == View.FOCUS_FORWARD) { 1677 direction = View.FOCUS_RIGHT; 1678 } else if (direction == View.FOCUS_BACKWARD) { 1679 direction = View.FOCUS_LEFT; 1680 } 1681 } else { 1682 if (direction == View.FOCUS_FORWARD) { 1683 direction = View.FOCUS_DOWN; 1684 } else if (direction == View.FOCUS_BACKWARD) { 1685 direction = View.FOCUS_UP; 1686 } 1687 } 1688 1689 final View nextFocus = previouslyFocusedRect == null ? 1690 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1691 FocusFinder.getInstance().findNextFocusFromRect(this, 1692 previouslyFocusedRect, direction); 1693 1694 if (nextFocus == null) { 1695 return false; 1696 } 1697 1698 if (isOffScreen(nextFocus)) { 1699 return false; 1700 } 1701 1702 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1703 } 1704 1705 @Override 1706 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1707 boolean immediate) { 1708 // offset into coordinate space of this scroll view 1709 rectangle.offset(child.getLeft() - child.getScrollX(), 1710 child.getTop() - child.getScrollY()); 1711 1712 return scrollToChildRect(rectangle, immediate); 1713 } 1714 1715 @Override 1716 public void requestLayout() { 1717 mIsLayoutDirty = true; 1718 super.requestLayout(); 1719 } 1720 1721 @Override 1722 protected void onDetachedFromWindow() { 1723 super.onDetachedFromWindow(); 1724 1725 if (mScrollStrictSpan != null) { 1726 mScrollStrictSpan.finish(); 1727 mScrollStrictSpan = null; 1728 } 1729 if (mFlingStrictSpan != null) { 1730 mFlingStrictSpan.finish(); 1731 mFlingStrictSpan = null; 1732 } 1733 } 1734 1735 @Override 1736 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1737 super.onLayout(changed, l, t, r, b); 1738 mIsLayoutDirty = false; 1739 // Give a child focus if it needs it 1740 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1741 scrollToChild(mChildToScrollTo); 1742 } 1743 mChildToScrollTo = null; 1744 1745 // Calling this with the present values causes it to re-clam them 1746 scrollTo(mScrollX, mScrollY); 1747 } 1748 1749 @Override 1750 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1751 super.onSizeChanged(w, h, oldw, oldh); 1752 1753 View currentFocused = findFocus(); 1754 if (null == currentFocused || this == currentFocused) 1755 return; 1756 1757 // If the currently-focused view was visible on the screen when the 1758 // screen was at the old height, then scroll the screen to make that 1759 // view visible with the new screen height. 1760 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1761 currentFocused.getDrawingRect(mTempRect); 1762 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1763 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1764 doScrollY(scrollDelta); 1765 } 1766 } 1767 1768 /** 1769 * Return true if child is an descendant of parent, (or equal to the parent). 1770 */ 1771 private boolean isViewDescendantOf(View child, View parent) { 1772 if (child == parent) { 1773 return true; 1774 } 1775 1776 final ViewParent theParent = child.getParent(); 1777 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1778 } 1779 1780 /** 1781 * Fling the scroll view 1782 * 1783 * @param velocityY The initial velocity in the Y direction. Positive 1784 * numbers mean that the finger/cursor is moving down the screen, 1785 * which means we want to scroll towards the top. 1786 */ 1787 public void fling(int velocityY) { 1788 if (getChildCount() > 0) { 1789 if (mHorizontal) { 1790 int width = getWidth() - mPaddingRight - mPaddingLeft; 1791 int right = getChildAt(0).getWidth(); 1792 1793 mScroller.fling(mScrollX, mScrollY, velocityY, 0, 1794 0, Math.max(0, right - width), 0, 0, width/2, 0); 1795 } else { 1796 int height = getHeight() - mPaddingBottom - mPaddingTop; 1797 int bottom = getChildAt(0).getHeight(); 1798 1799 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1800 Math.max(0, bottom - height), 0, height/2); 1801 } 1802 if (mFlingStrictSpan == null) { 1803 mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling"); 1804 } 1805 1806 invalidate(); 1807 } 1808 } 1809 1810 private void endDrag() { 1811 mIsBeingDragged = false; 1812 mIsOrthoDragged = false; 1813 mDownView = null; 1814 recycleVelocityTracker(); 1815 if (mScrollStrictSpan != null) { 1816 mScrollStrictSpan.finish(); 1817 mScrollStrictSpan = null; 1818 } 1819 } 1820 1821 /** 1822 * {@inheritDoc} 1823 * 1824 * <p>This version also clamps the scrolling to the bounds of our child. 1825 */ 1826 @Override 1827 public void scrollTo(int x, int y) { 1828 // we rely on the fact the View.scrollBy calls scrollTo. 1829 if (getChildCount() > 0) { 1830 View child = getChildAt(0); 1831 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1832 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1833 if (x != mScrollX || y != mScrollY) { 1834 super.scrollTo(x, y); 1835 } 1836 } 1837 } 1838 1839 private int clamp(int n, int my, int child) { 1840 if (my >= child || n < 0) { 1841 /* my >= child is this case: 1842 * |--------------- me ---------------| 1843 * |------ child ------| 1844 * or 1845 * |--------------- me ---------------| 1846 * |------ child ------| 1847 * or 1848 * |--------------- me ---------------| 1849 * |------ child ------| 1850 * 1851 * n < 0 is this case: 1852 * |------ me ------| 1853 * |-------- child --------| 1854 * |-- mScrollX --| 1855 */ 1856 return 0; 1857 } 1858 if ((my+n) > child) { 1859 /* this case: 1860 * |------ me ------| 1861 * |------ child ------| 1862 * |-- mScrollX --| 1863 */ 1864 return child-my; 1865 } 1866 return n; 1867 } 1868 1869} 1870