HorizontalScrollView.java revision 15279cfc566aee7f860ebfdfe9d4a6fbc0497362
1/* 2 * Copyright (C) 2009 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 android.widget; 18 19import android.content.Context; 20import android.content.res.TypedArray; 21import android.graphics.Canvas; 22import android.graphics.Rect; 23import android.os.Bundle; 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; 38 39import java.util.List; 40 41/** 42 * Layout container for a view hierarchy that can be scrolled by the user, 43 * allowing it to be larger than the physical display. A HorizontalScrollView 44 * is a {@link FrameLayout}, meaning you should place one child in it 45 * containing the entire contents to scroll; this child may itself be a layout 46 * manager with a complex hierarchy of objects. A child that is often used 47 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 48 * array of top-level items that the user can scroll through. 49 * 50 * <p>The {@link TextView} class also 51 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 52 * using the two together is possible to achieve the effect of a text view 53 * within a larger container. 54 * 55 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 56 * use either {@link ScrollView} or {@link ListView}. 57 * 58 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 59 */ 60public class HorizontalScrollView extends FrameLayout { 61 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 62 63 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 64 65 66 private long mLastScroll; 67 68 private final Rect mTempRect = new Rect(); 69 private OverScroller mScroller; 70 private EdgeEffect mEdgeGlowLeft; 71 private EdgeEffect mEdgeGlowRight; 72 73 /** 74 * Position of the last motion event. 75 */ 76 private int mLastMotionX; 77 78 /** 79 * True when the layout has changed but the traversal has not come through yet. 80 * Ideally the view hierarchy would keep track of this for us. 81 */ 82 private boolean mIsLayoutDirty = true; 83 84 /** 85 * The child to give focus to in the event that a child has requested focus while the 86 * layout is dirty. This prevents the scroll from being wrong if the child has not been 87 * laid out before requesting focus. 88 */ 89 private View mChildToScrollTo = null; 90 91 /** 92 * True if the user is currently dragging this ScrollView around. This is 93 * not the same as 'is being flinged', which can be checked by 94 * mScroller.isFinished() (flinging begins when the user lifts his finger). 95 */ 96 private boolean mIsBeingDragged = false; 97 98 /** 99 * Determines speed during touch scrolling 100 */ 101 private VelocityTracker mVelocityTracker; 102 103 /** 104 * When set to true, the scroll view measure its child to make it fill the currently 105 * visible area. 106 */ 107 @ViewDebug.ExportedProperty(category = "layout") 108 private boolean mFillViewport; 109 110 /** 111 * Whether arrow scrolling is animated. 112 */ 113 private boolean mSmoothScrollingEnabled = true; 114 115 private int mTouchSlop; 116 private int mMinimumVelocity; 117 private int mMaximumVelocity; 118 119 private int mOverscrollDistance; 120 private int mOverflingDistance; 121 122 /** 123 * ID of the active pointer. This is used to retain consistency during 124 * drags/flings if multiple pointers are used. 125 */ 126 private int mActivePointerId = INVALID_POINTER; 127 128 /** 129 * Sentinel value for no current active pointer. 130 * Used by {@link #mActivePointerId}. 131 */ 132 private static final int INVALID_POINTER = -1; 133 134 public HorizontalScrollView(Context context) { 135 this(context, null); 136 } 137 138 public HorizontalScrollView(Context context, AttributeSet attrs) { 139 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 140 } 141 142 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 143 super(context, attrs, defStyle); 144 initScrollView(); 145 146 TypedArray a = context.obtainStyledAttributes(attrs, 147 android.R.styleable.HorizontalScrollView, defStyle, 0); 148 149 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 150 151 a.recycle(); 152 } 153 154 @Override 155 protected float getLeftFadingEdgeStrength() { 156 if (getChildCount() == 0) { 157 return 0.0f; 158 } 159 160 final int length = getHorizontalFadingEdgeLength(); 161 if (mScrollX < length) { 162 return mScrollX / (float) length; 163 } 164 165 return 1.0f; 166 } 167 168 @Override 169 protected float getRightFadingEdgeStrength() { 170 if (getChildCount() == 0) { 171 return 0.0f; 172 } 173 174 final int length = getHorizontalFadingEdgeLength(); 175 final int rightEdge = getWidth() - mPaddingRight; 176 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 177 if (span < length) { 178 return span / (float) length; 179 } 180 181 return 1.0f; 182 } 183 184 /** 185 * @return The maximum amount this scroll view will scroll in response to 186 * an arrow event. 187 */ 188 public int getMaxScrollAmount() { 189 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 190 } 191 192 193 private void initScrollView() { 194 mScroller = new OverScroller(getContext()); 195 setFocusable(true); 196 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 197 setWillNotDraw(false); 198 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 199 mTouchSlop = configuration.getScaledTouchSlop(); 200 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 201 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 202 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 203 mOverflingDistance = configuration.getScaledOverflingDistance(); 204 } 205 206 @Override 207 public void addView(View child) { 208 if (getChildCount() > 0) { 209 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 210 } 211 212 super.addView(child); 213 } 214 215 @Override 216 public void addView(View child, int index) { 217 if (getChildCount() > 0) { 218 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 219 } 220 221 super.addView(child, index); 222 } 223 224 @Override 225 public void addView(View child, ViewGroup.LayoutParams params) { 226 if (getChildCount() > 0) { 227 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 228 } 229 230 super.addView(child, params); 231 } 232 233 @Override 234 public void addView(View child, int index, ViewGroup.LayoutParams params) { 235 if (getChildCount() > 0) { 236 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 237 } 238 239 super.addView(child, index, params); 240 } 241 242 /** 243 * @return Returns true this HorizontalScrollView can be scrolled 244 */ 245 private boolean canScroll() { 246 View child = getChildAt(0); 247 if (child != null) { 248 int childWidth = child.getWidth(); 249 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 250 } 251 return false; 252 } 253 254 /** 255 * Indicates whether this HorizontalScrollView's content is stretched to 256 * fill the viewport. 257 * 258 * @return True if the content fills the viewport, false otherwise. 259 * 260 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 261 */ 262 public boolean isFillViewport() { 263 return mFillViewport; 264 } 265 266 /** 267 * Indicates this HorizontalScrollView whether it should stretch its content width 268 * to fill the viewport or not. 269 * 270 * @param fillViewport True to stretch the content's width to the viewport's 271 * boundaries, false otherwise. 272 * 273 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 274 */ 275 public void setFillViewport(boolean fillViewport) { 276 if (fillViewport != mFillViewport) { 277 mFillViewport = fillViewport; 278 requestLayout(); 279 } 280 } 281 282 /** 283 * @return Whether arrow scrolling will animate its transition. 284 */ 285 public boolean isSmoothScrollingEnabled() { 286 return mSmoothScrollingEnabled; 287 } 288 289 /** 290 * Set whether arrow scrolling will animate its transition. 291 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 292 */ 293 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 294 mSmoothScrollingEnabled = smoothScrollingEnabled; 295 } 296 297 @Override 298 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 299 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 300 301 if (!mFillViewport) { 302 return; 303 } 304 305 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 306 if (widthMode == MeasureSpec.UNSPECIFIED) { 307 return; 308 } 309 310 if (getChildCount() > 0) { 311 final View child = getChildAt(0); 312 int width = getMeasuredWidth(); 313 if (child.getMeasuredWidth() < width) { 314 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 315 316 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 317 + mPaddingBottom, lp.height); 318 width -= mPaddingLeft; 319 width -= mPaddingRight; 320 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 321 322 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 323 } 324 } 325 } 326 327 @Override 328 public boolean dispatchKeyEvent(KeyEvent event) { 329 // Let the focused view and/or our descendants get the key first 330 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 331 } 332 333 /** 334 * You can call this function yourself to have the scroll view perform 335 * scrolling from a key event, just as if the event had been dispatched to 336 * it by the view hierarchy. 337 * 338 * @param event The key event to execute. 339 * @return Return true if the event was handled, else false. 340 */ 341 public boolean executeKeyEvent(KeyEvent event) { 342 mTempRect.setEmpty(); 343 344 if (!canScroll()) { 345 if (isFocused()) { 346 View currentFocused = findFocus(); 347 if (currentFocused == this) currentFocused = null; 348 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 349 currentFocused, View.FOCUS_RIGHT); 350 return nextFocused != null && nextFocused != this && 351 nextFocused.requestFocus(View.FOCUS_RIGHT); 352 } 353 return false; 354 } 355 356 boolean handled = false; 357 if (event.getAction() == KeyEvent.ACTION_DOWN) { 358 switch (event.getKeyCode()) { 359 case KeyEvent.KEYCODE_DPAD_LEFT: 360 if (!event.isAltPressed()) { 361 handled = arrowScroll(View.FOCUS_LEFT); 362 } else { 363 handled = fullScroll(View.FOCUS_LEFT); 364 } 365 break; 366 case KeyEvent.KEYCODE_DPAD_RIGHT: 367 if (!event.isAltPressed()) { 368 handled = arrowScroll(View.FOCUS_RIGHT); 369 } else { 370 handled = fullScroll(View.FOCUS_RIGHT); 371 } 372 break; 373 case KeyEvent.KEYCODE_SPACE: 374 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 375 break; 376 } 377 } 378 379 return handled; 380 } 381 382 private boolean inChild(int x, int y) { 383 if (getChildCount() > 0) { 384 final int scrollX = mScrollX; 385 final View child = getChildAt(0); 386 return !(y < child.getTop() 387 || y >= child.getBottom() 388 || x < child.getLeft() - scrollX 389 || x >= child.getRight() - scrollX); 390 } 391 return false; 392 } 393 394 private void initOrResetVelocityTracker() { 395 if (mVelocityTracker == null) { 396 mVelocityTracker = VelocityTracker.obtain(); 397 } else { 398 mVelocityTracker.clear(); 399 } 400 } 401 402 private void initVelocityTrackerIfNotExists() { 403 if (mVelocityTracker == null) { 404 mVelocityTracker = VelocityTracker.obtain(); 405 } 406 } 407 408 private void recycleVelocityTracker() { 409 if (mVelocityTracker != null) { 410 mVelocityTracker.recycle(); 411 mVelocityTracker = null; 412 } 413 } 414 415 @Override 416 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 417 if (disallowIntercept) { 418 recycleVelocityTracker(); 419 } 420 super.requestDisallowInterceptTouchEvent(disallowIntercept); 421 } 422 423 @Override 424 public boolean onInterceptTouchEvent(MotionEvent ev) { 425 /* 426 * This method JUST determines whether we want to intercept the motion. 427 * If we return true, onMotionEvent will be called and we do the actual 428 * scrolling there. 429 */ 430 431 /* 432 * Shortcut the most recurring case: the user is in the dragging 433 * state and he is moving his finger. We want to intercept this 434 * motion. 435 */ 436 final int action = ev.getAction(); 437 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 438 return true; 439 } 440 441 switch (action & MotionEvent.ACTION_MASK) { 442 case MotionEvent.ACTION_MOVE: { 443 /* 444 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 445 * whether the user has moved far enough from his original down touch. 446 */ 447 448 /* 449 * Locally do absolute value. mLastMotionX is set to the x value 450 * of the down event. 451 */ 452 final int activePointerId = mActivePointerId; 453 if (activePointerId == INVALID_POINTER) { 454 // If we don't have a valid id, the touch down wasn't on content. 455 break; 456 } 457 458 final int pointerIndex = ev.findPointerIndex(activePointerId); 459 final int x = (int) ev.getX(pointerIndex); 460 final int xDiff = (int) Math.abs(x - mLastMotionX); 461 if (xDiff > mTouchSlop) { 462 mIsBeingDragged = true; 463 mLastMotionX = x; 464 initVelocityTrackerIfNotExists(); 465 mVelocityTracker.addMovement(ev); 466 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 467 } 468 break; 469 } 470 471 case MotionEvent.ACTION_DOWN: { 472 final int x = (int) ev.getX(); 473 if (!inChild((int) x, (int) ev.getY())) { 474 mIsBeingDragged = false; 475 recycleVelocityTracker(); 476 break; 477 } 478 479 /* 480 * Remember location of down touch. 481 * ACTION_DOWN always refers to pointer index 0. 482 */ 483 mLastMotionX = x; 484 mActivePointerId = ev.getPointerId(0); 485 486 initOrResetVelocityTracker(); 487 mVelocityTracker.addMovement(ev); 488 489 /* 490 * If being flinged and user touches the screen, initiate drag; 491 * otherwise don't. mScroller.isFinished should be false when 492 * being flinged. 493 */ 494 mIsBeingDragged = !mScroller.isFinished(); 495 break; 496 } 497 498 case MotionEvent.ACTION_CANCEL: 499 case MotionEvent.ACTION_UP: 500 /* Release the drag */ 501 mIsBeingDragged = false; 502 mActivePointerId = INVALID_POINTER; 503 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 504 postInvalidateOnAnimation(); 505 } 506 break; 507 case MotionEvent.ACTION_POINTER_DOWN: { 508 final int index = ev.getActionIndex(); 509 mLastMotionX = (int) ev.getX(index); 510 mActivePointerId = ev.getPointerId(index); 511 break; 512 } 513 case MotionEvent.ACTION_POINTER_UP: 514 onSecondaryPointerUp(ev); 515 mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId)); 516 break; 517 } 518 519 /* 520 * The only time we want to intercept motion events is if we are in the 521 * drag mode. 522 */ 523 return mIsBeingDragged; 524 } 525 526 @Override 527 public boolean onTouchEvent(MotionEvent ev) { 528 initVelocityTrackerIfNotExists(); 529 mVelocityTracker.addMovement(ev); 530 531 final int action = ev.getAction(); 532 533 switch (action & MotionEvent.ACTION_MASK) { 534 case MotionEvent.ACTION_DOWN: { 535 if (getChildCount() == 0) { 536 return false; 537 } 538 if ((mIsBeingDragged = !mScroller.isFinished())) { 539 final ViewParent parent = getParent(); 540 if (parent != null) { 541 parent.requestDisallowInterceptTouchEvent(true); 542 } 543 } 544 545 /* 546 * If being flinged and user touches, stop the fling. isFinished 547 * will be false if being flinged. 548 */ 549 if (!mScroller.isFinished()) { 550 mScroller.abortAnimation(); 551 } 552 553 // Remember where the motion event started 554 mLastMotionX = (int) ev.getX(); 555 mActivePointerId = ev.getPointerId(0); 556 break; 557 } 558 case MotionEvent.ACTION_MOVE: 559 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 560 final int x = (int) ev.getX(activePointerIndex); 561 int deltaX = mLastMotionX - x; 562 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 563 final ViewParent parent = getParent(); 564 if (parent != null) { 565 parent.requestDisallowInterceptTouchEvent(true); 566 } 567 mIsBeingDragged = true; 568 if (deltaX > 0) { 569 deltaX -= mTouchSlop; 570 } else { 571 deltaX += mTouchSlop; 572 } 573 } 574 if (mIsBeingDragged) { 575 // Scroll to follow the motion event 576 mLastMotionX = x; 577 578 final int oldX = mScrollX; 579 final int oldY = mScrollY; 580 final int range = getScrollRange(); 581 final int overscrollMode = getOverScrollMode(); 582 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 583 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 584 585 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 586 mOverscrollDistance, 0, true)) { 587 // Break our velocity if we hit a scroll barrier. 588 mVelocityTracker.clear(); 589 } 590 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 591 592 if (canOverscroll) { 593 final int pulledToX = oldX + deltaX; 594 if (pulledToX < 0) { 595 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 596 if (!mEdgeGlowRight.isFinished()) { 597 mEdgeGlowRight.onRelease(); 598 } 599 } else if (pulledToX > range) { 600 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 601 if (!mEdgeGlowLeft.isFinished()) { 602 mEdgeGlowLeft.onRelease(); 603 } 604 } 605 if (mEdgeGlowLeft != null 606 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 607 postInvalidateOnAnimation(); 608 } 609 } 610 } 611 break; 612 case MotionEvent.ACTION_UP: 613 if (mIsBeingDragged) { 614 final VelocityTracker velocityTracker = mVelocityTracker; 615 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 616 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 617 618 if (getChildCount() > 0) { 619 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 620 fling(-initialVelocity); 621 } else { 622 if (mScroller.springBack(mScrollX, mScrollY, 0, 623 getScrollRange(), 0, 0)) { 624 postInvalidateOnAnimation(); 625 } 626 } 627 } 628 629 mActivePointerId = INVALID_POINTER; 630 mIsBeingDragged = false; 631 recycleVelocityTracker(); 632 633 if (mEdgeGlowLeft != null) { 634 mEdgeGlowLeft.onRelease(); 635 mEdgeGlowRight.onRelease(); 636 } 637 } 638 break; 639 case MotionEvent.ACTION_CANCEL: 640 if (mIsBeingDragged && getChildCount() > 0) { 641 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 642 postInvalidateOnAnimation(); 643 } 644 mActivePointerId = INVALID_POINTER; 645 mIsBeingDragged = false; 646 recycleVelocityTracker(); 647 648 if (mEdgeGlowLeft != null) { 649 mEdgeGlowLeft.onRelease(); 650 mEdgeGlowRight.onRelease(); 651 } 652 } 653 break; 654 case MotionEvent.ACTION_POINTER_UP: 655 onSecondaryPointerUp(ev); 656 break; 657 } 658 return true; 659 } 660 661 private void onSecondaryPointerUp(MotionEvent ev) { 662 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 663 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 664 final int pointerId = ev.getPointerId(pointerIndex); 665 if (pointerId == mActivePointerId) { 666 // This was our active pointer going up. Choose a new 667 // active pointer and adjust accordingly. 668 // TODO: Make this decision more intelligent. 669 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 670 mLastMotionX = (int) ev.getX(newPointerIndex); 671 mActivePointerId = ev.getPointerId(newPointerIndex); 672 if (mVelocityTracker != null) { 673 mVelocityTracker.clear(); 674 } 675 } 676 } 677 678 @Override 679 public boolean onGenericMotionEvent(MotionEvent event) { 680 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 681 switch (event.getAction()) { 682 case MotionEvent.ACTION_SCROLL: { 683 if (!mIsBeingDragged) { 684 final float hscroll; 685 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 686 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 687 } else { 688 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 689 } 690 if (hscroll != 0) { 691 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 692 final int range = getScrollRange(); 693 int oldScrollX = mScrollX; 694 int newScrollX = oldScrollX + delta; 695 if (newScrollX < 0) { 696 newScrollX = 0; 697 } else if (newScrollX > range) { 698 newScrollX = range; 699 } 700 if (newScrollX != oldScrollX) { 701 super.scrollTo(newScrollX, mScrollY); 702 return true; 703 } 704 } 705 } 706 } 707 } 708 } 709 return super.onGenericMotionEvent(event); 710 } 711 712 @Override 713 public boolean shouldDelayChildPressedState() { 714 return true; 715 } 716 717 @Override 718 protected void onOverScrolled(int scrollX, int scrollY, 719 boolean clampedX, boolean clampedY) { 720 // Treat animating scrolls differently; see #computeScroll() for why. 721 if (!mScroller.isFinished()) { 722 mScrollX = scrollX; 723 mScrollY = scrollY; 724 invalidateParentIfNeeded(); 725 if (clampedX) { 726 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 727 } 728 } else { 729 super.scrollTo(scrollX, scrollY); 730 } 731 732 awakenScrollBars(); 733 } 734 735 @Override 736 public boolean performAccessibilityAction(int action, Bundle arguments) { 737 if (super.performAccessibilityAction(action, arguments)) { 738 return true; 739 } 740 switch (action) { 741 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 742 if (!isEnabled()) { 743 return false; 744 } 745 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 746 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 747 if (targetScrollX != mScrollX) { 748 smoothScrollTo(targetScrollX, 0); 749 return true; 750 } 751 } return false; 752 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 753 if (!isEnabled()) { 754 return false; 755 } 756 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 757 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 758 if (targetScrollX != mScrollX) { 759 smoothScrollTo(targetScrollX, 0); 760 return true; 761 } 762 } return false; 763 } 764 return false; 765 } 766 767 @Override 768 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 769 super.onInitializeAccessibilityNodeInfo(info); 770 info.setClassName(HorizontalScrollView.class.getName()); 771 final int scrollRange = getScrollRange(); 772 if (scrollRange > 0) { 773 info.setScrollable(true); 774 if (isEnabled() && mScrollX > 0) { 775 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 776 } 777 if (isEnabled() && mScrollX < scrollRange) { 778 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 779 } 780 } 781 } 782 783 @Override 784 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 785 super.onInitializeAccessibilityEvent(event); 786 event.setClassName(HorizontalScrollView.class.getName()); 787 event.setScrollable(getScrollRange() > 0); 788 event.setScrollX(mScrollX); 789 event.setScrollY(mScrollY); 790 event.setMaxScrollX(getScrollRange()); 791 event.setMaxScrollY(mScrollY); 792 } 793 794 private int getScrollRange() { 795 int scrollRange = 0; 796 if (getChildCount() > 0) { 797 View child = getChildAt(0); 798 scrollRange = Math.max(0, 799 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 800 } 801 return scrollRange; 802 } 803 804 /** 805 * <p> 806 * Finds the next focusable component that fits in this View's bounds 807 * (excluding fading edges) pretending that this View's left is located at 808 * the parameter left. 809 * </p> 810 * 811 * @param leftFocus look for a candidate is the one at the left of the bounds 812 * if leftFocus is true, or at the right of the bounds if leftFocus 813 * is false 814 * @param left the left offset of the bounds in which a focusable must be 815 * found (the fading edge is assumed to start at this position) 816 * @param preferredFocusable the View that has highest priority and will be 817 * returned if it is within my bounds (null is valid) 818 * @return the next focusable component in the bounds or null if none can be found 819 */ 820 private View findFocusableViewInMyBounds(final boolean leftFocus, 821 final int left, View preferredFocusable) { 822 /* 823 * The fading edge's transparent side should be considered for focus 824 * since it's mostly visible, so we divide the actual fading edge length 825 * by 2. 826 */ 827 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 828 final int leftWithoutFadingEdge = left + fadingEdgeLength; 829 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 830 831 if ((preferredFocusable != null) 832 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 833 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 834 return preferredFocusable; 835 } 836 837 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 838 rightWithoutFadingEdge); 839 } 840 841 /** 842 * <p> 843 * Finds the next focusable component that fits in the specified bounds. 844 * </p> 845 * 846 * @param leftFocus look for a candidate is the one at the left of the bounds 847 * if leftFocus is true, or at the right of the bounds if 848 * leftFocus is false 849 * @param left the left offset of the bounds in which a focusable must be 850 * found 851 * @param right the right offset of the bounds in which a focusable must 852 * be found 853 * @return the next focusable component in the bounds or null if none can 854 * be found 855 */ 856 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 857 858 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 859 View focusCandidate = null; 860 861 /* 862 * A fully contained focusable is one where its left is below the bound's 863 * left, and its right is above the bound's right. A partially 864 * contained focusable is one where some part of it is within the 865 * bounds, but it also has some part that is not within bounds. A fully contained 866 * focusable is preferred to a partially contained focusable. 867 */ 868 boolean foundFullyContainedFocusable = false; 869 870 int count = focusables.size(); 871 for (int i = 0; i < count; i++) { 872 View view = focusables.get(i); 873 int viewLeft = view.getLeft(); 874 int viewRight = view.getRight(); 875 876 if (left < viewRight && viewLeft < right) { 877 /* 878 * the focusable is in the target area, it is a candidate for 879 * focusing 880 */ 881 882 final boolean viewIsFullyContained = (left < viewLeft) && 883 (viewRight < right); 884 885 if (focusCandidate == null) { 886 /* No candidate, take this one */ 887 focusCandidate = view; 888 foundFullyContainedFocusable = viewIsFullyContained; 889 } else { 890 final boolean viewIsCloserToBoundary = 891 (leftFocus && viewLeft < focusCandidate.getLeft()) || 892 (!leftFocus && viewRight > focusCandidate.getRight()); 893 894 if (foundFullyContainedFocusable) { 895 if (viewIsFullyContained && viewIsCloserToBoundary) { 896 /* 897 * We're dealing with only fully contained views, so 898 * it has to be closer to the boundary to beat our 899 * candidate 900 */ 901 focusCandidate = view; 902 } 903 } else { 904 if (viewIsFullyContained) { 905 /* Any fully contained view beats a partially contained view */ 906 focusCandidate = view; 907 foundFullyContainedFocusable = true; 908 } else if (viewIsCloserToBoundary) { 909 /* 910 * Partially contained view beats another partially 911 * contained view if it's closer 912 */ 913 focusCandidate = view; 914 } 915 } 916 } 917 } 918 } 919 920 return focusCandidate; 921 } 922 923 /** 924 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 925 * method will scroll the view by one page left or right and give the focus 926 * to the leftmost/rightmost component in the new visible area. If no 927 * component is a good candidate for focus, this scrollview reclaims the 928 * focus.</p> 929 * 930 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 931 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 932 * to go one page right 933 * @return true if the key event is consumed by this method, false otherwise 934 */ 935 public boolean pageScroll(int direction) { 936 boolean right = direction == View.FOCUS_RIGHT; 937 int width = getWidth(); 938 939 if (right) { 940 mTempRect.left = getScrollX() + width; 941 int count = getChildCount(); 942 if (count > 0) { 943 View view = getChildAt(0); 944 if (mTempRect.left + width > view.getRight()) { 945 mTempRect.left = view.getRight() - width; 946 } 947 } 948 } else { 949 mTempRect.left = getScrollX() - width; 950 if (mTempRect.left < 0) { 951 mTempRect.left = 0; 952 } 953 } 954 mTempRect.right = mTempRect.left + width; 955 956 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 957 } 958 959 /** 960 * <p>Handles scrolling in response to a "home/end" shortcut press. This 961 * method will scroll the view to the left or right and give the focus 962 * to the leftmost/rightmost component in the new visible area. If no 963 * component is a good candidate for focus, this scrollview reclaims the 964 * focus.</p> 965 * 966 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 967 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 968 * to go the right 969 * @return true if the key event is consumed by this method, false otherwise 970 */ 971 public boolean fullScroll(int direction) { 972 boolean right = direction == View.FOCUS_RIGHT; 973 int width = getWidth(); 974 975 mTempRect.left = 0; 976 mTempRect.right = width; 977 978 if (right) { 979 int count = getChildCount(); 980 if (count > 0) { 981 View view = getChildAt(0); 982 mTempRect.right = view.getRight(); 983 mTempRect.left = mTempRect.right - width; 984 } 985 } 986 987 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 988 } 989 990 /** 991 * <p>Scrolls the view to make the area defined by <code>left</code> and 992 * <code>right</code> visible. This method attempts to give the focus 993 * to a component visible in this area. If no component can be focused in 994 * the new visible area, the focus is reclaimed by this scrollview.</p> 995 * 996 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 997 * to go left {@link android.view.View#FOCUS_RIGHT} to right 998 * @param left the left offset of the new area to be made visible 999 * @param right the right offset of the new area to be made visible 1000 * @return true if the key event is consumed by this method, false otherwise 1001 */ 1002 private boolean scrollAndFocus(int direction, int left, int right) { 1003 boolean handled = true; 1004 1005 int width = getWidth(); 1006 int containerLeft = getScrollX(); 1007 int containerRight = containerLeft + width; 1008 boolean goLeft = direction == View.FOCUS_LEFT; 1009 1010 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1011 if (newFocused == null) { 1012 newFocused = this; 1013 } 1014 1015 if (left >= containerLeft && right <= containerRight) { 1016 handled = false; 1017 } else { 1018 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1019 doScrollX(delta); 1020 } 1021 1022 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1023 1024 return handled; 1025 } 1026 1027 /** 1028 * Handle scrolling in response to a left or right arrow click. 1029 * 1030 * @param direction The direction corresponding to the arrow key that was 1031 * pressed 1032 * @return True if we consumed the event, false otherwise 1033 */ 1034 public boolean arrowScroll(int direction) { 1035 1036 View currentFocused = findFocus(); 1037 if (currentFocused == this) currentFocused = null; 1038 1039 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1040 1041 final int maxJump = getMaxScrollAmount(); 1042 1043 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1044 nextFocused.getDrawingRect(mTempRect); 1045 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1046 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1047 doScrollX(scrollDelta); 1048 nextFocused.requestFocus(direction); 1049 } else { 1050 // no new focus 1051 int scrollDelta = maxJump; 1052 1053 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1054 scrollDelta = getScrollX(); 1055 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1056 1057 int daRight = getChildAt(0).getRight(); 1058 1059 int screenRight = getScrollX() + getWidth(); 1060 1061 if (daRight - screenRight < maxJump) { 1062 scrollDelta = daRight - screenRight; 1063 } 1064 } 1065 if (scrollDelta == 0) { 1066 return false; 1067 } 1068 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1069 } 1070 1071 if (currentFocused != null && currentFocused.isFocused() 1072 && isOffScreen(currentFocused)) { 1073 // previously focused item still has focus and is off screen, give 1074 // it up (take it back to ourselves) 1075 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1076 // sure to 1077 // get it) 1078 final int descendantFocusability = getDescendantFocusability(); // save 1079 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1080 requestFocus(); 1081 setDescendantFocusability(descendantFocusability); // restore 1082 } 1083 return true; 1084 } 1085 1086 /** 1087 * @return whether the descendant of this scroll view is scrolled off 1088 * screen. 1089 */ 1090 private boolean isOffScreen(View descendant) { 1091 return !isWithinDeltaOfScreen(descendant, 0); 1092 } 1093 1094 /** 1095 * @return whether the descendant of this scroll view is within delta 1096 * pixels of being on the screen. 1097 */ 1098 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1099 descendant.getDrawingRect(mTempRect); 1100 offsetDescendantRectToMyCoords(descendant, mTempRect); 1101 1102 return (mTempRect.right + delta) >= getScrollX() 1103 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1104 } 1105 1106 /** 1107 * Smooth scroll by a X delta 1108 * 1109 * @param delta the number of pixels to scroll by on the X axis 1110 */ 1111 private void doScrollX(int delta) { 1112 if (delta != 0) { 1113 if (mSmoothScrollingEnabled) { 1114 smoothScrollBy(delta, 0); 1115 } else { 1116 scrollBy(delta, 0); 1117 } 1118 } 1119 } 1120 1121 /** 1122 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1123 * 1124 * @param dx the number of pixels to scroll by on the X axis 1125 * @param dy the number of pixels to scroll by on the Y axis 1126 */ 1127 public final void smoothScrollBy(int dx, int dy) { 1128 if (getChildCount() == 0) { 1129 // Nothing to do. 1130 return; 1131 } 1132 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1133 if (duration > ANIMATED_SCROLL_GAP) { 1134 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1135 final int right = getChildAt(0).getWidth(); 1136 final int maxX = Math.max(0, right - width); 1137 final int scrollX = mScrollX; 1138 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1139 1140 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1141 postInvalidateOnAnimation(); 1142 } else { 1143 if (!mScroller.isFinished()) { 1144 mScroller.abortAnimation(); 1145 } 1146 scrollBy(dx, dy); 1147 } 1148 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1149 } 1150 1151 /** 1152 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1153 * 1154 * @param x the position where to scroll on the X axis 1155 * @param y the position where to scroll on the Y axis 1156 */ 1157 public final void smoothScrollTo(int x, int y) { 1158 smoothScrollBy(x - mScrollX, y - mScrollY); 1159 } 1160 1161 /** 1162 * <p>The scroll range of a scroll view is the overall width of all of its 1163 * children.</p> 1164 */ 1165 @Override 1166 protected int computeHorizontalScrollRange() { 1167 final int count = getChildCount(); 1168 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1169 if (count == 0) { 1170 return contentWidth; 1171 } 1172 1173 int scrollRange = getChildAt(0).getRight(); 1174 final int scrollX = mScrollX; 1175 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1176 if (scrollX < 0) { 1177 scrollRange -= scrollX; 1178 } else if (scrollX > overscrollRight) { 1179 scrollRange += scrollX - overscrollRight; 1180 } 1181 1182 return scrollRange; 1183 } 1184 1185 @Override 1186 protected int computeHorizontalScrollOffset() { 1187 return Math.max(0, super.computeHorizontalScrollOffset()); 1188 } 1189 1190 @Override 1191 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1192 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1193 1194 int childWidthMeasureSpec; 1195 int childHeightMeasureSpec; 1196 1197 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1198 + mPaddingBottom, lp.height); 1199 1200 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1201 1202 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1203 } 1204 1205 @Override 1206 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1207 int parentHeightMeasureSpec, int heightUsed) { 1208 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1209 1210 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1211 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1212 + heightUsed, lp.height); 1213 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1214 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1215 1216 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1217 } 1218 1219 @Override 1220 public void computeScroll() { 1221 if (mScroller.computeScrollOffset()) { 1222 // This is called at drawing time by ViewGroup. We don't want to 1223 // re-show the scrollbars at this point, which scrollTo will do, 1224 // so we replicate most of scrollTo here. 1225 // 1226 // It's a little odd to call onScrollChanged from inside the drawing. 1227 // 1228 // It is, except when you remember that computeScroll() is used to 1229 // animate scrolling. So unless we want to defer the onScrollChanged() 1230 // until the end of the animated scrolling, we don't really have a 1231 // choice here. 1232 // 1233 // I agree. The alternative, which I think would be worse, is to post 1234 // something and tell the subclasses later. This is bad because there 1235 // will be a window where mScrollX/Y is different from what the app 1236 // thinks it is. 1237 // 1238 int oldX = mScrollX; 1239 int oldY = mScrollY; 1240 int x = mScroller.getCurrX(); 1241 int y = mScroller.getCurrY(); 1242 1243 if (oldX != x || oldY != y) { 1244 final int range = getScrollRange(); 1245 final int overscrollMode = getOverScrollMode(); 1246 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1247 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1248 1249 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1250 mOverflingDistance, 0, false); 1251 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1252 1253 if (canOverscroll) { 1254 if (x < 0 && oldX >= 0) { 1255 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1256 } else if (x > range && oldX <= range) { 1257 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1258 } 1259 } 1260 } 1261 1262 if (!awakenScrollBars()) { 1263 postInvalidateOnAnimation(); 1264 } 1265 } 1266 } 1267 1268 /** 1269 * Scrolls the view to the given child. 1270 * 1271 * @param child the View to scroll to 1272 */ 1273 private void scrollToChild(View child) { 1274 child.getDrawingRect(mTempRect); 1275 1276 /* Offset from child's local coordinates to ScrollView coordinates */ 1277 offsetDescendantRectToMyCoords(child, mTempRect); 1278 1279 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1280 1281 if (scrollDelta != 0) { 1282 scrollBy(scrollDelta, 0); 1283 } 1284 } 1285 1286 /** 1287 * If rect is off screen, scroll just enough to get it (or at least the 1288 * first screen size chunk of it) on screen. 1289 * 1290 * @param rect The rectangle. 1291 * @param immediate True to scroll immediately without animation 1292 * @return true if scrolling was performed 1293 */ 1294 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1295 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1296 final boolean scroll = delta != 0; 1297 if (scroll) { 1298 if (immediate) { 1299 scrollBy(delta, 0); 1300 } else { 1301 smoothScrollBy(delta, 0); 1302 } 1303 } 1304 return scroll; 1305 } 1306 1307 /** 1308 * Compute the amount to scroll in the X direction in order to get 1309 * a rectangle completely on the screen (or, if taller than the screen, 1310 * at least the first screen size chunk of it). 1311 * 1312 * @param rect The rect. 1313 * @return The scroll delta. 1314 */ 1315 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1316 if (getChildCount() == 0) return 0; 1317 1318 int width = getWidth(); 1319 int screenLeft = getScrollX(); 1320 int screenRight = screenLeft + width; 1321 1322 int fadingEdge = getHorizontalFadingEdgeLength(); 1323 1324 // leave room for left fading edge as long as rect isn't at very left 1325 if (rect.left > 0) { 1326 screenLeft += fadingEdge; 1327 } 1328 1329 // leave room for right fading edge as long as rect isn't at very right 1330 if (rect.right < getChildAt(0).getWidth()) { 1331 screenRight -= fadingEdge; 1332 } 1333 1334 int scrollXDelta = 0; 1335 1336 if (rect.right > screenRight && rect.left > screenLeft) { 1337 // need to move right to get it in view: move right just enough so 1338 // that the entire rectangle is in view (or at least the first 1339 // screen size chunk). 1340 1341 if (rect.width() > width) { 1342 // just enough to get screen size chunk on 1343 scrollXDelta += (rect.left - screenLeft); 1344 } else { 1345 // get entire rect at right of screen 1346 scrollXDelta += (rect.right - screenRight); 1347 } 1348 1349 // make sure we aren't scrolling beyond the end of our content 1350 int right = getChildAt(0).getRight(); 1351 int distanceToRight = right - screenRight; 1352 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1353 1354 } else if (rect.left < screenLeft && rect.right < screenRight) { 1355 // need to move right to get it in view: move right just enough so that 1356 // entire rectangle is in view (or at least the first screen 1357 // size chunk of it). 1358 1359 if (rect.width() > width) { 1360 // screen size chunk 1361 scrollXDelta -= (screenRight - rect.right); 1362 } else { 1363 // entire rect at left 1364 scrollXDelta -= (screenLeft - rect.left); 1365 } 1366 1367 // make sure we aren't scrolling any further than the left our content 1368 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1369 } 1370 return scrollXDelta; 1371 } 1372 1373 @Override 1374 public void requestChildFocus(View child, View focused) { 1375 if (!mIsLayoutDirty) { 1376 scrollToChild(focused); 1377 } else { 1378 // The child may not be laid out yet, we can't compute the scroll yet 1379 mChildToScrollTo = focused; 1380 } 1381 super.requestChildFocus(child, focused); 1382 } 1383 1384 1385 /** 1386 * When looking for focus in children of a scroll view, need to be a little 1387 * more careful not to give focus to something that is scrolled off screen. 1388 * 1389 * This is more expensive than the default {@link android.view.ViewGroup} 1390 * implementation, otherwise this behavior might have been made the default. 1391 */ 1392 @Override 1393 protected boolean onRequestFocusInDescendants(int direction, 1394 Rect previouslyFocusedRect) { 1395 1396 // convert from forward / backward notation to up / down / left / right 1397 // (ugh). 1398 if (direction == View.FOCUS_FORWARD) { 1399 direction = View.FOCUS_RIGHT; 1400 } else if (direction == View.FOCUS_BACKWARD) { 1401 direction = View.FOCUS_LEFT; 1402 } 1403 1404 final View nextFocus = previouslyFocusedRect == null ? 1405 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1406 FocusFinder.getInstance().findNextFocusFromRect(this, 1407 previouslyFocusedRect, direction); 1408 1409 if (nextFocus == null) { 1410 return false; 1411 } 1412 1413 if (isOffScreen(nextFocus)) { 1414 return false; 1415 } 1416 1417 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1418 } 1419 1420 @Override 1421 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1422 boolean immediate) { 1423 // offset into coordinate space of this scroll view 1424 rectangle.offset(child.getLeft() - child.getScrollX(), 1425 child.getTop() - child.getScrollY()); 1426 1427 return scrollToChildRect(rectangle, immediate); 1428 } 1429 1430 @Override 1431 public void requestLayout() { 1432 mIsLayoutDirty = true; 1433 super.requestLayout(); 1434 } 1435 1436 @Override 1437 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1438 super.onLayout(changed, l, t, r, b); 1439 mIsLayoutDirty = false; 1440 // Give a child focus if it needs it 1441 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1442 scrollToChild(mChildToScrollTo); 1443 } 1444 mChildToScrollTo = null; 1445 1446 // Calling this with the present values causes it to re-claim them 1447 scrollTo(mScrollX, mScrollY); 1448 } 1449 1450 @Override 1451 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1452 super.onSizeChanged(w, h, oldw, oldh); 1453 1454 View currentFocused = findFocus(); 1455 if (null == currentFocused || this == currentFocused) 1456 return; 1457 1458 final int maxJump = mRight - mLeft; 1459 1460 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1461 currentFocused.getDrawingRect(mTempRect); 1462 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1463 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1464 doScrollX(scrollDelta); 1465 } 1466 } 1467 1468 /** 1469 * Return true if child is a descendant of parent, (or equal to the parent). 1470 */ 1471 private static boolean isViewDescendantOf(View child, View parent) { 1472 if (child == parent) { 1473 return true; 1474 } 1475 1476 final ViewParent theParent = child.getParent(); 1477 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1478 } 1479 1480 /** 1481 * Fling the scroll view 1482 * 1483 * @param velocityX The initial velocity in the X direction. Positive 1484 * numbers mean that the finger/cursor is moving down the screen, 1485 * which means we want to scroll towards the left. 1486 */ 1487 public void fling(int velocityX) { 1488 if (getChildCount() > 0) { 1489 int width = getWidth() - mPaddingRight - mPaddingLeft; 1490 int right = getChildAt(0).getWidth(); 1491 1492 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1493 Math.max(0, right - width), 0, 0, width/2, 0); 1494 1495 final boolean movingRight = velocityX > 0; 1496 1497 View currentFocused = findFocus(); 1498 View newFocused = findFocusableViewInMyBounds(movingRight, 1499 mScroller.getFinalX(), currentFocused); 1500 1501 if (newFocused == null) { 1502 newFocused = this; 1503 } 1504 1505 if (newFocused != currentFocused) { 1506 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1507 } 1508 1509 postInvalidateOnAnimation(); 1510 } 1511 } 1512 1513 /** 1514 * {@inheritDoc} 1515 * 1516 * <p>This version also clamps the scrolling to the bounds of our child. 1517 */ 1518 @Override 1519 public void scrollTo(int x, int y) { 1520 // we rely on the fact the View.scrollBy calls scrollTo. 1521 if (getChildCount() > 0) { 1522 View child = getChildAt(0); 1523 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1524 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1525 if (x != mScrollX || y != mScrollY) { 1526 super.scrollTo(x, y); 1527 } 1528 } 1529 } 1530 1531 @Override 1532 public void setOverScrollMode(int mode) { 1533 if (mode != OVER_SCROLL_NEVER) { 1534 if (mEdgeGlowLeft == null) { 1535 Context context = getContext(); 1536 mEdgeGlowLeft = new EdgeEffect(context); 1537 mEdgeGlowRight = new EdgeEffect(context); 1538 } 1539 } else { 1540 mEdgeGlowLeft = null; 1541 mEdgeGlowRight = null; 1542 } 1543 super.setOverScrollMode(mode); 1544 } 1545 1546 @SuppressWarnings({"SuspiciousNameCombination"}) 1547 @Override 1548 public void draw(Canvas canvas) { 1549 super.draw(canvas); 1550 if (mEdgeGlowLeft != null) { 1551 final int scrollX = mScrollX; 1552 if (!mEdgeGlowLeft.isFinished()) { 1553 final int restoreCount = canvas.save(); 1554 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1555 1556 canvas.rotate(270); 1557 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1558 mEdgeGlowLeft.setSize(height, getWidth()); 1559 if (mEdgeGlowLeft.draw(canvas)) { 1560 postInvalidateOnAnimation(); 1561 } 1562 canvas.restoreToCount(restoreCount); 1563 } 1564 if (!mEdgeGlowRight.isFinished()) { 1565 final int restoreCount = canvas.save(); 1566 final int width = getWidth(); 1567 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1568 1569 canvas.rotate(90); 1570 canvas.translate(-mPaddingTop, 1571 -(Math.max(getScrollRange(), scrollX) + width)); 1572 mEdgeGlowRight.setSize(height, width); 1573 if (mEdgeGlowRight.draw(canvas)) { 1574 postInvalidateOnAnimation(); 1575 } 1576 canvas.restoreToCount(restoreCount); 1577 } 1578 } 1579 } 1580 1581 private static int clamp(int n, int my, int child) { 1582 if (my >= child || n < 0) { 1583 return 0; 1584 } 1585 if ((my + n) > child) { 1586 return child - my; 1587 } 1588 return n; 1589 } 1590} 1591