HorizontalScrollView.java revision a1dc761c8322355eb1bb71d3d6c9c603c1d1fc0f
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>You should never use a HorizontalScrollView with a {@link ListView}, since 51 * ListView takes care of its own scrolling. Most importantly, doing this 52 * defeats all of the important optimizations in ListView for dealing with 53 * large lists, since it effectively forces the ListView to display its entire 54 * list of items to fill up the infinite container supplied by HorizontalScrollView. 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>HorizontalScrollView only supports horizontal scrolling. 62 * 63 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 64 */ 65public class HorizontalScrollView extends FrameLayout { 66 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 67 68 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 69 70 71 private long mLastScroll; 72 73 private final Rect mTempRect = new Rect(); 74 private OverScroller mScroller; 75 private EdgeEffect mEdgeGlowLeft; 76 private EdgeEffect mEdgeGlowRight; 77 78 /** 79 * Position of the last motion event. 80 */ 81 private int mLastMotionX; 82 83 /** 84 * True when the layout has changed but the traversal has not come through yet. 85 * Ideally the view hierarchy would keep track of this for us. 86 */ 87 private boolean mIsLayoutDirty = true; 88 89 /** 90 * The child to give focus to in the event that a child has requested focus while the 91 * layout is dirty. This prevents the scroll from being wrong if the child has not been 92 * laid out before requesting focus. 93 */ 94 private View mChildToScrollTo = null; 95 96 /** 97 * True if the user is currently dragging this ScrollView around. This is 98 * not the same as 'is being flinged', which can be checked by 99 * mScroller.isFinished() (flinging begins when the user lifts his finger). 100 */ 101 private boolean mIsBeingDragged = false; 102 103 /** 104 * Determines speed during touch scrolling 105 */ 106 private VelocityTracker mVelocityTracker; 107 108 /** 109 * When set to true, the scroll view measure its child to make it fill the currently 110 * visible area. 111 */ 112 @ViewDebug.ExportedProperty(category = "layout") 113 private boolean mFillViewport; 114 115 /** 116 * Whether arrow scrolling is animated. 117 */ 118 private boolean mSmoothScrollingEnabled = true; 119 120 private int mTouchSlop; 121 private int mMinimumVelocity; 122 private int mMaximumVelocity; 123 124 private int mOverscrollDistance; 125 private int mOverflingDistance; 126 127 /** 128 * ID of the active pointer. This is used to retain consistency during 129 * drags/flings if multiple pointers are used. 130 */ 131 private int mActivePointerId = INVALID_POINTER; 132 133 /** 134 * Sentinel value for no current active pointer. 135 * Used by {@link #mActivePointerId}. 136 */ 137 private static final int INVALID_POINTER = -1; 138 139 public HorizontalScrollView(Context context) { 140 this(context, null); 141 } 142 143 public HorizontalScrollView(Context context, AttributeSet attrs) { 144 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 145 } 146 147 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 148 super(context, attrs, defStyle); 149 initScrollView(); 150 151 TypedArray a = context.obtainStyledAttributes(attrs, 152 android.R.styleable.HorizontalScrollView, defStyle, 0); 153 154 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 155 156 a.recycle(); 157 } 158 159 @Override 160 protected float getLeftFadingEdgeStrength() { 161 if (getChildCount() == 0) { 162 return 0.0f; 163 } 164 165 final int length = getHorizontalFadingEdgeLength(); 166 if (mScrollX < length) { 167 return mScrollX / (float) length; 168 } 169 170 return 1.0f; 171 } 172 173 @Override 174 protected float getRightFadingEdgeStrength() { 175 if (getChildCount() == 0) { 176 return 0.0f; 177 } 178 179 final int length = getHorizontalFadingEdgeLength(); 180 final int rightEdge = getWidth() - mPaddingRight; 181 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 182 if (span < length) { 183 return span / (float) length; 184 } 185 186 return 1.0f; 187 } 188 189 /** 190 * @return The maximum amount this scroll view will scroll in response to 191 * an arrow event. 192 */ 193 public int getMaxScrollAmount() { 194 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 195 } 196 197 198 private void initScrollView() { 199 mScroller = new OverScroller(getContext()); 200 setFocusable(true); 201 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 202 setWillNotDraw(false); 203 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 204 mTouchSlop = configuration.getScaledTouchSlop(); 205 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 206 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 207 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 208 mOverflingDistance = configuration.getScaledOverflingDistance(); 209 } 210 211 @Override 212 public void addView(View child) { 213 if (getChildCount() > 0) { 214 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 215 } 216 217 super.addView(child); 218 } 219 220 @Override 221 public void addView(View child, int index) { 222 if (getChildCount() > 0) { 223 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 224 } 225 226 super.addView(child, index); 227 } 228 229 @Override 230 public void addView(View child, ViewGroup.LayoutParams params) { 231 if (getChildCount() > 0) { 232 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 233 } 234 235 super.addView(child, params); 236 } 237 238 @Override 239 public void addView(View child, int index, ViewGroup.LayoutParams params) { 240 if (getChildCount() > 0) { 241 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 242 } 243 244 super.addView(child, index, params); 245 } 246 247 /** 248 * @return Returns true this HorizontalScrollView can be scrolled 249 */ 250 private boolean canScroll() { 251 View child = getChildAt(0); 252 if (child != null) { 253 int childWidth = child.getWidth(); 254 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 255 } 256 return false; 257 } 258 259 /** 260 * Indicates whether this HorizontalScrollView's content is stretched to 261 * fill the viewport. 262 * 263 * @return True if the content fills the viewport, false otherwise. 264 * 265 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 266 */ 267 public boolean isFillViewport() { 268 return mFillViewport; 269 } 270 271 /** 272 * Indicates this HorizontalScrollView whether it should stretch its content width 273 * to fill the viewport or not. 274 * 275 * @param fillViewport True to stretch the content's width to the viewport's 276 * boundaries, false otherwise. 277 * 278 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 279 */ 280 public void setFillViewport(boolean fillViewport) { 281 if (fillViewport != mFillViewport) { 282 mFillViewport = fillViewport; 283 requestLayout(); 284 } 285 } 286 287 /** 288 * @return Whether arrow scrolling will animate its transition. 289 */ 290 public boolean isSmoothScrollingEnabled() { 291 return mSmoothScrollingEnabled; 292 } 293 294 /** 295 * Set whether arrow scrolling will animate its transition. 296 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 297 */ 298 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 299 mSmoothScrollingEnabled = smoothScrollingEnabled; 300 } 301 302 @Override 303 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 304 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 305 306 if (!mFillViewport) { 307 return; 308 } 309 310 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 311 if (widthMode == MeasureSpec.UNSPECIFIED) { 312 return; 313 } 314 315 if (getChildCount() > 0) { 316 final View child = getChildAt(0); 317 int width = getMeasuredWidth(); 318 if (child.getMeasuredWidth() < width) { 319 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 320 321 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 322 + mPaddingBottom, lp.height); 323 width -= mPaddingLeft; 324 width -= mPaddingRight; 325 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 326 327 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 328 } 329 } 330 } 331 332 @Override 333 public boolean dispatchKeyEvent(KeyEvent event) { 334 // Let the focused view and/or our descendants get the key first 335 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 336 } 337 338 /** 339 * You can call this function yourself to have the scroll view perform 340 * scrolling from a key event, just as if the event had been dispatched to 341 * it by the view hierarchy. 342 * 343 * @param event The key event to execute. 344 * @return Return true if the event was handled, else false. 345 */ 346 public boolean executeKeyEvent(KeyEvent event) { 347 mTempRect.setEmpty(); 348 349 if (!canScroll()) { 350 if (isFocused()) { 351 View currentFocused = findFocus(); 352 if (currentFocused == this) currentFocused = null; 353 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 354 currentFocused, View.FOCUS_RIGHT); 355 return nextFocused != null && nextFocused != this && 356 nextFocused.requestFocus(View.FOCUS_RIGHT); 357 } 358 return false; 359 } 360 361 boolean handled = false; 362 if (event.getAction() == KeyEvent.ACTION_DOWN) { 363 switch (event.getKeyCode()) { 364 case KeyEvent.KEYCODE_DPAD_LEFT: 365 if (!event.isAltPressed()) { 366 handled = arrowScroll(View.FOCUS_LEFT); 367 } else { 368 handled = fullScroll(View.FOCUS_LEFT); 369 } 370 break; 371 case KeyEvent.KEYCODE_DPAD_RIGHT: 372 if (!event.isAltPressed()) { 373 handled = arrowScroll(View.FOCUS_RIGHT); 374 } else { 375 handled = fullScroll(View.FOCUS_RIGHT); 376 } 377 break; 378 case KeyEvent.KEYCODE_SPACE: 379 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 380 break; 381 } 382 } 383 384 return handled; 385 } 386 387 private boolean inChild(int x, int y) { 388 if (getChildCount() > 0) { 389 final int scrollX = mScrollX; 390 final View child = getChildAt(0); 391 return !(y < child.getTop() 392 || y >= child.getBottom() 393 || x < child.getLeft() - scrollX 394 || x >= child.getRight() - scrollX); 395 } 396 return false; 397 } 398 399 private void initOrResetVelocityTracker() { 400 if (mVelocityTracker == null) { 401 mVelocityTracker = VelocityTracker.obtain(); 402 } else { 403 mVelocityTracker.clear(); 404 } 405 } 406 407 private void initVelocityTrackerIfNotExists() { 408 if (mVelocityTracker == null) { 409 mVelocityTracker = VelocityTracker.obtain(); 410 } 411 } 412 413 private void recycleVelocityTracker() { 414 if (mVelocityTracker != null) { 415 mVelocityTracker.recycle(); 416 mVelocityTracker = null; 417 } 418 } 419 420 @Override 421 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 422 if (disallowIntercept) { 423 recycleVelocityTracker(); 424 } 425 super.requestDisallowInterceptTouchEvent(disallowIntercept); 426 } 427 428 @Override 429 public boolean onInterceptTouchEvent(MotionEvent ev) { 430 /* 431 * This method JUST determines whether we want to intercept the motion. 432 * If we return true, onMotionEvent will be called and we do the actual 433 * scrolling there. 434 */ 435 436 /* 437 * Shortcut the most recurring case: the user is in the dragging 438 * state and he is moving his finger. We want to intercept this 439 * motion. 440 */ 441 final int action = ev.getAction(); 442 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 443 return true; 444 } 445 446 switch (action & MotionEvent.ACTION_MASK) { 447 case MotionEvent.ACTION_MOVE: { 448 /* 449 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 450 * whether the user has moved far enough from his original down touch. 451 */ 452 453 /* 454 * Locally do absolute value. mLastMotionX is set to the x value 455 * of the down event. 456 */ 457 final int activePointerId = mActivePointerId; 458 if (activePointerId == INVALID_POINTER) { 459 // If we don't have a valid id, the touch down wasn't on content. 460 break; 461 } 462 463 final int pointerIndex = ev.findPointerIndex(activePointerId); 464 final int x = (int) ev.getX(pointerIndex); 465 final int xDiff = (int) Math.abs(x - mLastMotionX); 466 if (xDiff > mTouchSlop) { 467 mIsBeingDragged = true; 468 mLastMotionX = x; 469 initVelocityTrackerIfNotExists(); 470 mVelocityTracker.addMovement(ev); 471 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 472 } 473 break; 474 } 475 476 case MotionEvent.ACTION_DOWN: { 477 final int x = (int) ev.getX(); 478 if (!inChild((int) x, (int) ev.getY())) { 479 mIsBeingDragged = false; 480 recycleVelocityTracker(); 481 break; 482 } 483 484 /* 485 * Remember location of down touch. 486 * ACTION_DOWN always refers to pointer index 0. 487 */ 488 mLastMotionX = x; 489 mActivePointerId = ev.getPointerId(0); 490 491 initOrResetVelocityTracker(); 492 mVelocityTracker.addMovement(ev); 493 494 /* 495 * If being flinged and user touches the screen, initiate drag; 496 * otherwise don't. mScroller.isFinished should be false when 497 * being flinged. 498 */ 499 mIsBeingDragged = !mScroller.isFinished(); 500 break; 501 } 502 503 case MotionEvent.ACTION_CANCEL: 504 case MotionEvent.ACTION_UP: 505 /* Release the drag */ 506 mIsBeingDragged = false; 507 mActivePointerId = INVALID_POINTER; 508 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 509 postInvalidateOnAnimation(); 510 } 511 break; 512 case MotionEvent.ACTION_POINTER_DOWN: { 513 final int index = ev.getActionIndex(); 514 mLastMotionX = (int) ev.getX(index); 515 mActivePointerId = ev.getPointerId(index); 516 break; 517 } 518 case MotionEvent.ACTION_POINTER_UP: 519 onSecondaryPointerUp(ev); 520 mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId)); 521 break; 522 } 523 524 /* 525 * The only time we want to intercept motion events is if we are in the 526 * drag mode. 527 */ 528 return mIsBeingDragged; 529 } 530 531 @Override 532 public boolean onTouchEvent(MotionEvent ev) { 533 initVelocityTrackerIfNotExists(); 534 mVelocityTracker.addMovement(ev); 535 536 final int action = ev.getAction(); 537 538 switch (action & MotionEvent.ACTION_MASK) { 539 case MotionEvent.ACTION_DOWN: { 540 if (getChildCount() == 0) { 541 return false; 542 } 543 if ((mIsBeingDragged = !mScroller.isFinished())) { 544 final ViewParent parent = getParent(); 545 if (parent != null) { 546 parent.requestDisallowInterceptTouchEvent(true); 547 } 548 } 549 550 /* 551 * If being flinged and user touches, stop the fling. isFinished 552 * will be false if being flinged. 553 */ 554 if (!mScroller.isFinished()) { 555 mScroller.abortAnimation(); 556 } 557 558 // Remember where the motion event started 559 mLastMotionX = (int) ev.getX(); 560 mActivePointerId = ev.getPointerId(0); 561 break; 562 } 563 case MotionEvent.ACTION_MOVE: 564 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 565 final int x = (int) ev.getX(activePointerIndex); 566 int deltaX = mLastMotionX - x; 567 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 568 final ViewParent parent = getParent(); 569 if (parent != null) { 570 parent.requestDisallowInterceptTouchEvent(true); 571 } 572 mIsBeingDragged = true; 573 if (deltaX > 0) { 574 deltaX -= mTouchSlop; 575 } else { 576 deltaX += mTouchSlop; 577 } 578 } 579 if (mIsBeingDragged) { 580 // Scroll to follow the motion event 581 mLastMotionX = x; 582 583 final int oldX = mScrollX; 584 final int oldY = mScrollY; 585 final int range = getScrollRange(); 586 final int overscrollMode = getOverScrollMode(); 587 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 588 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 589 590 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 591 mOverscrollDistance, 0, true)) { 592 // Break our velocity if we hit a scroll barrier. 593 mVelocityTracker.clear(); 594 } 595 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 596 597 if (canOverscroll) { 598 final int pulledToX = oldX + deltaX; 599 if (pulledToX < 0) { 600 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 601 if (!mEdgeGlowRight.isFinished()) { 602 mEdgeGlowRight.onRelease(); 603 } 604 } else if (pulledToX > range) { 605 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 606 if (!mEdgeGlowLeft.isFinished()) { 607 mEdgeGlowLeft.onRelease(); 608 } 609 } 610 if (mEdgeGlowLeft != null 611 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 612 postInvalidateOnAnimation(); 613 } 614 } 615 } 616 break; 617 case MotionEvent.ACTION_UP: 618 if (mIsBeingDragged) { 619 final VelocityTracker velocityTracker = mVelocityTracker; 620 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 621 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 622 623 if (getChildCount() > 0) { 624 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 625 fling(-initialVelocity); 626 } else { 627 if (mScroller.springBack(mScrollX, mScrollY, 0, 628 getScrollRange(), 0, 0)) { 629 postInvalidateOnAnimation(); 630 } 631 } 632 } 633 634 mActivePointerId = INVALID_POINTER; 635 mIsBeingDragged = false; 636 recycleVelocityTracker(); 637 638 if (mEdgeGlowLeft != null) { 639 mEdgeGlowLeft.onRelease(); 640 mEdgeGlowRight.onRelease(); 641 } 642 } 643 break; 644 case MotionEvent.ACTION_CANCEL: 645 if (mIsBeingDragged && getChildCount() > 0) { 646 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 647 postInvalidateOnAnimation(); 648 } 649 mActivePointerId = INVALID_POINTER; 650 mIsBeingDragged = false; 651 recycleVelocityTracker(); 652 653 if (mEdgeGlowLeft != null) { 654 mEdgeGlowLeft.onRelease(); 655 mEdgeGlowRight.onRelease(); 656 } 657 } 658 break; 659 case MotionEvent.ACTION_POINTER_UP: 660 onSecondaryPointerUp(ev); 661 break; 662 } 663 return true; 664 } 665 666 private void onSecondaryPointerUp(MotionEvent ev) { 667 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 668 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 669 final int pointerId = ev.getPointerId(pointerIndex); 670 if (pointerId == mActivePointerId) { 671 // This was our active pointer going up. Choose a new 672 // active pointer and adjust accordingly. 673 // TODO: Make this decision more intelligent. 674 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 675 mLastMotionX = (int) ev.getX(newPointerIndex); 676 mActivePointerId = ev.getPointerId(newPointerIndex); 677 if (mVelocityTracker != null) { 678 mVelocityTracker.clear(); 679 } 680 } 681 } 682 683 @Override 684 public boolean onGenericMotionEvent(MotionEvent event) { 685 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 686 switch (event.getAction()) { 687 case MotionEvent.ACTION_SCROLL: { 688 if (!mIsBeingDragged) { 689 final float hscroll; 690 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 691 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 692 } else { 693 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 694 } 695 if (hscroll != 0) { 696 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 697 final int range = getScrollRange(); 698 int oldScrollX = mScrollX; 699 int newScrollX = oldScrollX + delta; 700 if (newScrollX < 0) { 701 newScrollX = 0; 702 } else if (newScrollX > range) { 703 newScrollX = range; 704 } 705 if (newScrollX != oldScrollX) { 706 super.scrollTo(newScrollX, mScrollY); 707 return true; 708 } 709 } 710 } 711 } 712 } 713 } 714 return super.onGenericMotionEvent(event); 715 } 716 717 @Override 718 public boolean shouldDelayChildPressedState() { 719 return true; 720 } 721 722 @Override 723 protected void onOverScrolled(int scrollX, int scrollY, 724 boolean clampedX, boolean clampedY) { 725 // Treat animating scrolls differently; see #computeScroll() for why. 726 if (!mScroller.isFinished()) { 727 mScrollX = scrollX; 728 mScrollY = scrollY; 729 invalidateParentIfNeeded(); 730 if (clampedX) { 731 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 732 } 733 } else { 734 super.scrollTo(scrollX, scrollY); 735 } 736 737 awakenScrollBars(); 738 } 739 740 @Override 741 public boolean performAccessibilityAction(int action, Bundle arguments) { 742 switch (action) { 743 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 744 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 745 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 746 if (targetScrollX != mScrollX) { 747 smoothScrollTo(targetScrollX, 0); 748 return true; 749 } 750 } return false; 751 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 752 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 753 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 754 if (targetScrollX != mScrollX) { 755 smoothScrollTo(targetScrollX, 0); 756 return true; 757 } 758 } return false; 759 } 760 return super.performAccessibilityAction(action, arguments); 761 } 762 763 @Override 764 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 765 super.onInitializeAccessibilityNodeInfo(info); 766 info.setClassName(HorizontalScrollView.class.getName()); 767 final int scrollRange = getScrollRange(); 768 if (scrollRange > 0) { 769 info.setScrollable(true); 770 if (mScrollX > 0) { 771 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 772 } 773 if (mScrollX < scrollRange) { 774 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 775 } 776 } 777 } 778 779 @Override 780 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 781 super.onInitializeAccessibilityEvent(event); 782 event.setClassName(HorizontalScrollView.class.getName()); 783 event.setScrollable(getScrollRange() > 0); 784 event.setScrollX(mScrollX); 785 event.setScrollY(mScrollY); 786 event.setMaxScrollX(getScrollRange()); 787 event.setMaxScrollY(mScrollY); 788 } 789 790 private int getScrollRange() { 791 int scrollRange = 0; 792 if (getChildCount() > 0) { 793 View child = getChildAt(0); 794 scrollRange = Math.max(0, 795 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 796 } 797 return scrollRange; 798 } 799 800 /** 801 * <p> 802 * Finds the next focusable component that fits in this View's bounds 803 * (excluding fading edges) pretending that this View's left is located at 804 * the parameter left. 805 * </p> 806 * 807 * @param leftFocus look for a candidate is the one at the left of the bounds 808 * if leftFocus is true, or at the right of the bounds if leftFocus 809 * is false 810 * @param left the left offset of the bounds in which a focusable must be 811 * found (the fading edge is assumed to start at this position) 812 * @param preferredFocusable the View that has highest priority and will be 813 * returned if it is within my bounds (null is valid) 814 * @return the next focusable component in the bounds or null if none can be found 815 */ 816 private View findFocusableViewInMyBounds(final boolean leftFocus, 817 final int left, View preferredFocusable) { 818 /* 819 * The fading edge's transparent side should be considered for focus 820 * since it's mostly visible, so we divide the actual fading edge length 821 * by 2. 822 */ 823 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 824 final int leftWithoutFadingEdge = left + fadingEdgeLength; 825 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 826 827 if ((preferredFocusable != null) 828 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 829 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 830 return preferredFocusable; 831 } 832 833 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 834 rightWithoutFadingEdge); 835 } 836 837 /** 838 * <p> 839 * Finds the next focusable component that fits in the specified bounds. 840 * </p> 841 * 842 * @param leftFocus look for a candidate is the one at the left of the bounds 843 * if leftFocus is true, or at the right of the bounds if 844 * leftFocus is false 845 * @param left the left offset of the bounds in which a focusable must be 846 * found 847 * @param right the right offset of the bounds in which a focusable must 848 * be found 849 * @return the next focusable component in the bounds or null if none can 850 * be found 851 */ 852 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 853 854 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 855 View focusCandidate = null; 856 857 /* 858 * A fully contained focusable is one where its left is below the bound's 859 * left, and its right is above the bound's right. A partially 860 * contained focusable is one where some part of it is within the 861 * bounds, but it also has some part that is not within bounds. A fully contained 862 * focusable is preferred to a partially contained focusable. 863 */ 864 boolean foundFullyContainedFocusable = false; 865 866 int count = focusables.size(); 867 for (int i = 0; i < count; i++) { 868 View view = focusables.get(i); 869 int viewLeft = view.getLeft(); 870 int viewRight = view.getRight(); 871 872 if (left < viewRight && viewLeft < right) { 873 /* 874 * the focusable is in the target area, it is a candidate for 875 * focusing 876 */ 877 878 final boolean viewIsFullyContained = (left < viewLeft) && 879 (viewRight < right); 880 881 if (focusCandidate == null) { 882 /* No candidate, take this one */ 883 focusCandidate = view; 884 foundFullyContainedFocusable = viewIsFullyContained; 885 } else { 886 final boolean viewIsCloserToBoundary = 887 (leftFocus && viewLeft < focusCandidate.getLeft()) || 888 (!leftFocus && viewRight > focusCandidate.getRight()); 889 890 if (foundFullyContainedFocusable) { 891 if (viewIsFullyContained && viewIsCloserToBoundary) { 892 /* 893 * We're dealing with only fully contained views, so 894 * it has to be closer to the boundary to beat our 895 * candidate 896 */ 897 focusCandidate = view; 898 } 899 } else { 900 if (viewIsFullyContained) { 901 /* Any fully contained view beats a partially contained view */ 902 focusCandidate = view; 903 foundFullyContainedFocusable = true; 904 } else if (viewIsCloserToBoundary) { 905 /* 906 * Partially contained view beats another partially 907 * contained view if it's closer 908 */ 909 focusCandidate = view; 910 } 911 } 912 } 913 } 914 } 915 916 return focusCandidate; 917 } 918 919 /** 920 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 921 * method will scroll the view by one page left or right and give the focus 922 * to the leftmost/rightmost component in the new visible area. If no 923 * component is a good candidate for focus, this scrollview reclaims the 924 * focus.</p> 925 * 926 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 927 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 928 * to go one page right 929 * @return true if the key event is consumed by this method, false otherwise 930 */ 931 public boolean pageScroll(int direction) { 932 boolean right = direction == View.FOCUS_RIGHT; 933 int width = getWidth(); 934 935 if (right) { 936 mTempRect.left = getScrollX() + width; 937 int count = getChildCount(); 938 if (count > 0) { 939 View view = getChildAt(0); 940 if (mTempRect.left + width > view.getRight()) { 941 mTempRect.left = view.getRight() - width; 942 } 943 } 944 } else { 945 mTempRect.left = getScrollX() - width; 946 if (mTempRect.left < 0) { 947 mTempRect.left = 0; 948 } 949 } 950 mTempRect.right = mTempRect.left + width; 951 952 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 953 } 954 955 /** 956 * <p>Handles scrolling in response to a "home/end" shortcut press. This 957 * method will scroll the view to the left or right and give the focus 958 * to the leftmost/rightmost component in the new visible area. If no 959 * component is a good candidate for focus, this scrollview reclaims the 960 * focus.</p> 961 * 962 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 963 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 964 * to go the right 965 * @return true if the key event is consumed by this method, false otherwise 966 */ 967 public boolean fullScroll(int direction) { 968 boolean right = direction == View.FOCUS_RIGHT; 969 int width = getWidth(); 970 971 mTempRect.left = 0; 972 mTempRect.right = width; 973 974 if (right) { 975 int count = getChildCount(); 976 if (count > 0) { 977 View view = getChildAt(0); 978 mTempRect.right = view.getRight(); 979 mTempRect.left = mTempRect.right - width; 980 } 981 } 982 983 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 984 } 985 986 /** 987 * <p>Scrolls the view to make the area defined by <code>left</code> and 988 * <code>right</code> visible. This method attempts to give the focus 989 * to a component visible in this area. If no component can be focused in 990 * the new visible area, the focus is reclaimed by this scrollview.</p> 991 * 992 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 993 * to go left {@link android.view.View#FOCUS_RIGHT} to right 994 * @param left the left offset of the new area to be made visible 995 * @param right the right offset of the new area to be made visible 996 * @return true if the key event is consumed by this method, false otherwise 997 */ 998 private boolean scrollAndFocus(int direction, int left, int right) { 999 boolean handled = true; 1000 1001 int width = getWidth(); 1002 int containerLeft = getScrollX(); 1003 int containerRight = containerLeft + width; 1004 boolean goLeft = direction == View.FOCUS_LEFT; 1005 1006 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1007 if (newFocused == null) { 1008 newFocused = this; 1009 } 1010 1011 if (left >= containerLeft && right <= containerRight) { 1012 handled = false; 1013 } else { 1014 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1015 doScrollX(delta); 1016 } 1017 1018 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1019 1020 return handled; 1021 } 1022 1023 /** 1024 * Handle scrolling in response to a left or right arrow click. 1025 * 1026 * @param direction The direction corresponding to the arrow key that was 1027 * pressed 1028 * @return True if we consumed the event, false otherwise 1029 */ 1030 public boolean arrowScroll(int direction) { 1031 1032 View currentFocused = findFocus(); 1033 if (currentFocused == this) currentFocused = null; 1034 1035 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1036 1037 final int maxJump = getMaxScrollAmount(); 1038 1039 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1040 nextFocused.getDrawingRect(mTempRect); 1041 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1042 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1043 doScrollX(scrollDelta); 1044 nextFocused.requestFocus(direction); 1045 } else { 1046 // no new focus 1047 int scrollDelta = maxJump; 1048 1049 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1050 scrollDelta = getScrollX(); 1051 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1052 1053 int daRight = getChildAt(0).getRight(); 1054 1055 int screenRight = getScrollX() + getWidth(); 1056 1057 if (daRight - screenRight < maxJump) { 1058 scrollDelta = daRight - screenRight; 1059 } 1060 } 1061 if (scrollDelta == 0) { 1062 return false; 1063 } 1064 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1065 } 1066 1067 if (currentFocused != null && currentFocused.isFocused() 1068 && isOffScreen(currentFocused)) { 1069 // previously focused item still has focus and is off screen, give 1070 // it up (take it back to ourselves) 1071 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1072 // sure to 1073 // get it) 1074 final int descendantFocusability = getDescendantFocusability(); // save 1075 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1076 requestFocus(); 1077 setDescendantFocusability(descendantFocusability); // restore 1078 } 1079 return true; 1080 } 1081 1082 /** 1083 * @return whether the descendant of this scroll view is scrolled off 1084 * screen. 1085 */ 1086 private boolean isOffScreen(View descendant) { 1087 return !isWithinDeltaOfScreen(descendant, 0); 1088 } 1089 1090 /** 1091 * @return whether the descendant of this scroll view is within delta 1092 * pixels of being on the screen. 1093 */ 1094 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1095 descendant.getDrawingRect(mTempRect); 1096 offsetDescendantRectToMyCoords(descendant, mTempRect); 1097 1098 return (mTempRect.right + delta) >= getScrollX() 1099 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1100 } 1101 1102 /** 1103 * Smooth scroll by a X delta 1104 * 1105 * @param delta the number of pixels to scroll by on the X axis 1106 */ 1107 private void doScrollX(int delta) { 1108 if (delta != 0) { 1109 if (mSmoothScrollingEnabled) { 1110 smoothScrollBy(delta, 0); 1111 } else { 1112 scrollBy(delta, 0); 1113 } 1114 } 1115 } 1116 1117 /** 1118 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1119 * 1120 * @param dx the number of pixels to scroll by on the X axis 1121 * @param dy the number of pixels to scroll by on the Y axis 1122 */ 1123 public final void smoothScrollBy(int dx, int dy) { 1124 if (getChildCount() == 0) { 1125 // Nothing to do. 1126 return; 1127 } 1128 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1129 if (duration > ANIMATED_SCROLL_GAP) { 1130 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1131 final int right = getChildAt(0).getWidth(); 1132 final int maxX = Math.max(0, right - width); 1133 final int scrollX = mScrollX; 1134 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1135 1136 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1137 postInvalidateOnAnimation(); 1138 } else { 1139 if (!mScroller.isFinished()) { 1140 mScroller.abortAnimation(); 1141 } 1142 scrollBy(dx, dy); 1143 } 1144 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1145 } 1146 1147 /** 1148 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1149 * 1150 * @param x the position where to scroll on the X axis 1151 * @param y the position where to scroll on the Y axis 1152 */ 1153 public final void smoothScrollTo(int x, int y) { 1154 smoothScrollBy(x - mScrollX, y - mScrollY); 1155 } 1156 1157 /** 1158 * <p>The scroll range of a scroll view is the overall width of all of its 1159 * children.</p> 1160 */ 1161 @Override 1162 protected int computeHorizontalScrollRange() { 1163 final int count = getChildCount(); 1164 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1165 if (count == 0) { 1166 return contentWidth; 1167 } 1168 1169 int scrollRange = getChildAt(0).getRight(); 1170 final int scrollX = mScrollX; 1171 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1172 if (scrollX < 0) { 1173 scrollRange -= scrollX; 1174 } else if (scrollX > overscrollRight) { 1175 scrollRange += scrollX - overscrollRight; 1176 } 1177 1178 return scrollRange; 1179 } 1180 1181 @Override 1182 protected int computeHorizontalScrollOffset() { 1183 return Math.max(0, super.computeHorizontalScrollOffset()); 1184 } 1185 1186 @Override 1187 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1188 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1189 1190 int childWidthMeasureSpec; 1191 int childHeightMeasureSpec; 1192 1193 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1194 + mPaddingBottom, lp.height); 1195 1196 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1197 1198 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1199 } 1200 1201 @Override 1202 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1203 int parentHeightMeasureSpec, int heightUsed) { 1204 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1205 1206 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1207 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1208 + heightUsed, lp.height); 1209 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1210 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1211 1212 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1213 } 1214 1215 @Override 1216 public void computeScroll() { 1217 if (mScroller.computeScrollOffset()) { 1218 // This is called at drawing time by ViewGroup. We don't want to 1219 // re-show the scrollbars at this point, which scrollTo will do, 1220 // so we replicate most of scrollTo here. 1221 // 1222 // It's a little odd to call onScrollChanged from inside the drawing. 1223 // 1224 // It is, except when you remember that computeScroll() is used to 1225 // animate scrolling. So unless we want to defer the onScrollChanged() 1226 // until the end of the animated scrolling, we don't really have a 1227 // choice here. 1228 // 1229 // I agree. The alternative, which I think would be worse, is to post 1230 // something and tell the subclasses later. This is bad because there 1231 // will be a window where mScrollX/Y is different from what the app 1232 // thinks it is. 1233 // 1234 int oldX = mScrollX; 1235 int oldY = mScrollY; 1236 int x = mScroller.getCurrX(); 1237 int y = mScroller.getCurrY(); 1238 1239 if (oldX != x || oldY != y) { 1240 final int range = getScrollRange(); 1241 final int overscrollMode = getOverScrollMode(); 1242 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1243 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1244 1245 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1246 mOverflingDistance, 0, false); 1247 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1248 1249 if (canOverscroll) { 1250 if (x < 0 && oldX >= 0) { 1251 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1252 } else if (x > range && oldX <= range) { 1253 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1254 } 1255 } 1256 } 1257 1258 if (!awakenScrollBars()) { 1259 postInvalidateOnAnimation(); 1260 } 1261 } 1262 } 1263 1264 /** 1265 * Scrolls the view to the given child. 1266 * 1267 * @param child the View to scroll to 1268 */ 1269 private void scrollToChild(View child) { 1270 child.getDrawingRect(mTempRect); 1271 1272 /* Offset from child's local coordinates to ScrollView coordinates */ 1273 offsetDescendantRectToMyCoords(child, mTempRect); 1274 1275 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1276 1277 if (scrollDelta != 0) { 1278 scrollBy(scrollDelta, 0); 1279 } 1280 } 1281 1282 /** 1283 * If rect is off screen, scroll just enough to get it (or at least the 1284 * first screen size chunk of it) on screen. 1285 * 1286 * @param rect The rectangle. 1287 * @param immediate True to scroll immediately without animation 1288 * @return true if scrolling was performed 1289 */ 1290 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1291 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1292 final boolean scroll = delta != 0; 1293 if (scroll) { 1294 if (immediate) { 1295 scrollBy(delta, 0); 1296 } else { 1297 smoothScrollBy(delta, 0); 1298 } 1299 } 1300 return scroll; 1301 } 1302 1303 /** 1304 * Compute the amount to scroll in the X direction in order to get 1305 * a rectangle completely on the screen (or, if taller than the screen, 1306 * at least the first screen size chunk of it). 1307 * 1308 * @param rect The rect. 1309 * @return The scroll delta. 1310 */ 1311 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1312 if (getChildCount() == 0) return 0; 1313 1314 int width = getWidth(); 1315 int screenLeft = getScrollX(); 1316 int screenRight = screenLeft + width; 1317 1318 int fadingEdge = getHorizontalFadingEdgeLength(); 1319 1320 // leave room for left fading edge as long as rect isn't at very left 1321 if (rect.left > 0) { 1322 screenLeft += fadingEdge; 1323 } 1324 1325 // leave room for right fading edge as long as rect isn't at very right 1326 if (rect.right < getChildAt(0).getWidth()) { 1327 screenRight -= fadingEdge; 1328 } 1329 1330 int scrollXDelta = 0; 1331 1332 if (rect.right > screenRight && rect.left > screenLeft) { 1333 // need to move right to get it in view: move right just enough so 1334 // that the entire rectangle is in view (or at least the first 1335 // screen size chunk). 1336 1337 if (rect.width() > width) { 1338 // just enough to get screen size chunk on 1339 scrollXDelta += (rect.left - screenLeft); 1340 } else { 1341 // get entire rect at right of screen 1342 scrollXDelta += (rect.right - screenRight); 1343 } 1344 1345 // make sure we aren't scrolling beyond the end of our content 1346 int right = getChildAt(0).getRight(); 1347 int distanceToRight = right - screenRight; 1348 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1349 1350 } else if (rect.left < screenLeft && rect.right < screenRight) { 1351 // need to move right to get it in view: move right just enough so that 1352 // entire rectangle is in view (or at least the first screen 1353 // size chunk of it). 1354 1355 if (rect.width() > width) { 1356 // screen size chunk 1357 scrollXDelta -= (screenRight - rect.right); 1358 } else { 1359 // entire rect at left 1360 scrollXDelta -= (screenLeft - rect.left); 1361 } 1362 1363 // make sure we aren't scrolling any further than the left our content 1364 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1365 } 1366 return scrollXDelta; 1367 } 1368 1369 @Override 1370 public void requestChildFocus(View child, View focused) { 1371 if (!mIsLayoutDirty) { 1372 scrollToChild(focused); 1373 } else { 1374 // The child may not be laid out yet, we can't compute the scroll yet 1375 mChildToScrollTo = focused; 1376 } 1377 super.requestChildFocus(child, focused); 1378 } 1379 1380 1381 /** 1382 * When looking for focus in children of a scroll view, need to be a little 1383 * more careful not to give focus to something that is scrolled off screen. 1384 * 1385 * This is more expensive than the default {@link android.view.ViewGroup} 1386 * implementation, otherwise this behavior might have been made the default. 1387 */ 1388 @Override 1389 protected boolean onRequestFocusInDescendants(int direction, 1390 Rect previouslyFocusedRect) { 1391 1392 // convert from forward / backward notation to up / down / left / right 1393 // (ugh). 1394 if (direction == View.FOCUS_FORWARD) { 1395 direction = View.FOCUS_RIGHT; 1396 } else if (direction == View.FOCUS_BACKWARD) { 1397 direction = View.FOCUS_LEFT; 1398 } 1399 1400 final View nextFocus = previouslyFocusedRect == null ? 1401 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1402 FocusFinder.getInstance().findNextFocusFromRect(this, 1403 previouslyFocusedRect, direction); 1404 1405 if (nextFocus == null) { 1406 return false; 1407 } 1408 1409 if (isOffScreen(nextFocus)) { 1410 return false; 1411 } 1412 1413 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1414 } 1415 1416 @Override 1417 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1418 boolean immediate) { 1419 // offset into coordinate space of this scroll view 1420 rectangle.offset(child.getLeft() - child.getScrollX(), 1421 child.getTop() - child.getScrollY()); 1422 1423 return scrollToChildRect(rectangle, immediate); 1424 } 1425 1426 @Override 1427 public void requestLayout() { 1428 mIsLayoutDirty = true; 1429 super.requestLayout(); 1430 } 1431 1432 @Override 1433 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1434 super.onLayout(changed, l, t, r, b); 1435 mIsLayoutDirty = false; 1436 // Give a child focus if it needs it 1437 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1438 scrollToChild(mChildToScrollTo); 1439 } 1440 mChildToScrollTo = null; 1441 1442 // Calling this with the present values causes it to re-claim them 1443 scrollTo(mScrollX, mScrollY); 1444 } 1445 1446 @Override 1447 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1448 super.onSizeChanged(w, h, oldw, oldh); 1449 1450 View currentFocused = findFocus(); 1451 if (null == currentFocused || this == currentFocused) 1452 return; 1453 1454 final int maxJump = mRight - mLeft; 1455 1456 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1457 currentFocused.getDrawingRect(mTempRect); 1458 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1459 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1460 doScrollX(scrollDelta); 1461 } 1462 } 1463 1464 /** 1465 * Return true if child is a descendant of parent, (or equal to the parent). 1466 */ 1467 private static boolean isViewDescendantOf(View child, View parent) { 1468 if (child == parent) { 1469 return true; 1470 } 1471 1472 final ViewParent theParent = child.getParent(); 1473 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1474 } 1475 1476 /** 1477 * Fling the scroll view 1478 * 1479 * @param velocityX The initial velocity in the X direction. Positive 1480 * numbers mean that the finger/cursor is moving down the screen, 1481 * which means we want to scroll towards the left. 1482 */ 1483 public void fling(int velocityX) { 1484 if (getChildCount() > 0) { 1485 int width = getWidth() - mPaddingRight - mPaddingLeft; 1486 int right = getChildAt(0).getWidth(); 1487 1488 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1489 Math.max(0, right - width), 0, 0, width/2, 0); 1490 1491 final boolean movingRight = velocityX > 0; 1492 1493 View currentFocused = findFocus(); 1494 View newFocused = findFocusableViewInMyBounds(movingRight, 1495 mScroller.getFinalX(), currentFocused); 1496 1497 if (newFocused == null) { 1498 newFocused = this; 1499 } 1500 1501 if (newFocused != currentFocused) { 1502 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1503 } 1504 1505 postInvalidateOnAnimation(); 1506 } 1507 } 1508 1509 /** 1510 * {@inheritDoc} 1511 * 1512 * <p>This version also clamps the scrolling to the bounds of our child. 1513 */ 1514 @Override 1515 public void scrollTo(int x, int y) { 1516 // we rely on the fact the View.scrollBy calls scrollTo. 1517 if (getChildCount() > 0) { 1518 View child = getChildAt(0); 1519 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1520 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1521 if (x != mScrollX || y != mScrollY) { 1522 super.scrollTo(x, y); 1523 } 1524 } 1525 } 1526 1527 @Override 1528 public void setOverScrollMode(int mode) { 1529 if (mode != OVER_SCROLL_NEVER) { 1530 if (mEdgeGlowLeft == null) { 1531 Context context = getContext(); 1532 mEdgeGlowLeft = new EdgeEffect(context); 1533 mEdgeGlowRight = new EdgeEffect(context); 1534 } 1535 } else { 1536 mEdgeGlowLeft = null; 1537 mEdgeGlowRight = null; 1538 } 1539 super.setOverScrollMode(mode); 1540 } 1541 1542 @SuppressWarnings({"SuspiciousNameCombination"}) 1543 @Override 1544 public void draw(Canvas canvas) { 1545 super.draw(canvas); 1546 if (mEdgeGlowLeft != null) { 1547 final int scrollX = mScrollX; 1548 if (!mEdgeGlowLeft.isFinished()) { 1549 final int restoreCount = canvas.save(); 1550 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1551 1552 canvas.rotate(270); 1553 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1554 mEdgeGlowLeft.setSize(height, getWidth()); 1555 if (mEdgeGlowLeft.draw(canvas)) { 1556 postInvalidateOnAnimation(); 1557 } 1558 canvas.restoreToCount(restoreCount); 1559 } 1560 if (!mEdgeGlowRight.isFinished()) { 1561 final int restoreCount = canvas.save(); 1562 final int width = getWidth(); 1563 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1564 1565 canvas.rotate(90); 1566 canvas.translate(-mPaddingTop, 1567 -(Math.max(getScrollRange(), scrollX) + width)); 1568 mEdgeGlowRight.setSize(height, width); 1569 if (mEdgeGlowRight.draw(canvas)) { 1570 postInvalidateOnAnimation(); 1571 } 1572 canvas.restoreToCount(restoreCount); 1573 } 1574 } 1575 } 1576 1577 private static int clamp(int n, int my, int child) { 1578 if (my >= child || n < 0) { 1579 return 0; 1580 } 1581 if ((my + n) > child) { 1582 return child - my; 1583 } 1584 return n; 1585 } 1586} 1587