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