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.Build; 24 import android.os.Bundle; 25 import android.os.Parcel; 26 import android.os.Parcelable; 27 import android.util.AttributeSet; 28 import android.util.Log; 29 import android.view.FocusFinder; 30 import android.view.InputDevice; 31 import android.view.KeyEvent; 32 import android.view.MotionEvent; 33 import android.view.VelocityTracker; 34 import android.view.View; 35 import android.view.ViewConfiguration; 36 import android.view.ViewDebug; 37 import android.view.ViewGroup; 38 import android.view.ViewParent; 39 import android.view.accessibility.AccessibilityEvent; 40 import android.view.accessibility.AccessibilityNodeInfo; 41 import android.view.animation.AnimationUtils; 42 43 import java.util.List; 44 45 /** 46 * Layout container for a view hierarchy that can be scrolled by the user, 47 * allowing it to be larger than the physical display. A HorizontalScrollView 48 * is a {@link FrameLayout}, meaning you should place one child in it 49 * containing the entire contents to scroll; this child may itself be a layout 50 * manager with a complex hierarchy of objects. A child that is often used 51 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 52 * array of top-level items that the user can scroll through. 53 * 54 * <p>The {@link TextView} class also 55 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 56 * using the two together is possible to achieve the effect of a text view 57 * within a larger container. 58 * 59 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 60 * use either {@link ScrollView} or {@link ListView}. 61 * 62 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 63 */ 64 public class HorizontalScrollView extends FrameLayout { 65 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 66 67 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 68 69 private static final String TAG = "HorizontalScrollView"; 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 private SavedState mSavedState; 140 141 public HorizontalScrollView(Context context) { 142 this(context, null); 143 } 144 145 public HorizontalScrollView(Context context, AttributeSet attrs) { 146 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 147 } 148 149 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 150 super(context, attrs, defStyle); 151 initScrollView(); 152 153 TypedArray a = context.obtainStyledAttributes(attrs, 154 android.R.styleable.HorizontalScrollView, defStyle, 0); 155 156 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 157 158 a.recycle(); 159 } 160 161 @Override 162 protected float getLeftFadingEdgeStrength() { 163 if (getChildCount() == 0) { 164 return 0.0f; 165 } 166 167 final int length = getHorizontalFadingEdgeLength(); 168 if (mScrollX < length) { 169 return mScrollX / (float) length; 170 } 171 172 return 1.0f; 173 } 174 175 @Override 176 protected float getRightFadingEdgeStrength() { 177 if (getChildCount() == 0) { 178 return 0.0f; 179 } 180 181 final int length = getHorizontalFadingEdgeLength(); 182 final int rightEdge = getWidth() - mPaddingRight; 183 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 184 if (span < length) { 185 return span / (float) length; 186 } 187 188 return 1.0f; 189 } 190 191 /** 192 * @return The maximum amount this scroll view will scroll in response to 193 * an arrow event. 194 */ 195 public int getMaxScrollAmount() { 196 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 197 } 198 199 200 private void initScrollView() { 201 mScroller = new OverScroller(getContext()); 202 setFocusable(true); 203 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 204 setWillNotDraw(false); 205 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 206 mTouchSlop = configuration.getScaledTouchSlop(); 207 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 208 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 209 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 210 mOverflingDistance = configuration.getScaledOverflingDistance(); 211 } 212 213 @Override 214 public void addView(View child) { 215 if (getChildCount() > 0) { 216 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 217 } 218 219 super.addView(child); 220 } 221 222 @Override 223 public void addView(View child, int index) { 224 if (getChildCount() > 0) { 225 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 226 } 227 228 super.addView(child, index); 229 } 230 231 @Override 232 public void addView(View child, ViewGroup.LayoutParams params) { 233 if (getChildCount() > 0) { 234 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 235 } 236 237 super.addView(child, params); 238 } 239 240 @Override 241 public void addView(View child, int index, ViewGroup.LayoutParams params) { 242 if (getChildCount() > 0) { 243 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 244 } 245 246 super.addView(child, index, params); 247 } 248 249 /** 250 * @return Returns true this HorizontalScrollView can be scrolled 251 */ 252 private boolean canScroll() { 253 View child = getChildAt(0); 254 if (child != null) { 255 int childWidth = child.getWidth(); 256 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 257 } 258 return false; 259 } 260 261 /** 262 * Indicates whether this HorizontalScrollView's content is stretched to 263 * fill the viewport. 264 * 265 * @return True if the content fills the viewport, false otherwise. 266 * 267 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 268 */ 269 public boolean isFillViewport() { 270 return mFillViewport; 271 } 272 273 /** 274 * Indicates this HorizontalScrollView whether it should stretch its content width 275 * to fill the viewport or not. 276 * 277 * @param fillViewport True to stretch the content's width to the viewport's 278 * boundaries, false otherwise. 279 * 280 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 281 */ 282 public void setFillViewport(boolean fillViewport) { 283 if (fillViewport != mFillViewport) { 284 mFillViewport = fillViewport; 285 requestLayout(); 286 } 287 } 288 289 /** 290 * @return Whether arrow scrolling will animate its transition. 291 */ 292 public boolean isSmoothScrollingEnabled() { 293 return mSmoothScrollingEnabled; 294 } 295 296 /** 297 * Set whether arrow scrolling will animate its transition. 298 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 299 */ 300 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 301 mSmoothScrollingEnabled = smoothScrollingEnabled; 302 } 303 304 @Override 305 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 306 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 307 308 if (!mFillViewport) { 309 return; 310 } 311 312 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 313 if (widthMode == MeasureSpec.UNSPECIFIED) { 314 return; 315 } 316 317 if (getChildCount() > 0) { 318 final View child = getChildAt(0); 319 int width = getMeasuredWidth(); 320 if (child.getMeasuredWidth() < width) { 321 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 322 323 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 324 + mPaddingBottom, lp.height); 325 width -= mPaddingLeft; 326 width -= mPaddingRight; 327 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 328 329 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 330 } 331 } 332 } 333 334 @Override 335 public boolean dispatchKeyEvent(KeyEvent event) { 336 // Let the focused view and/or our descendants get the key first 337 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 338 } 339 340 /** 341 * You can call this function yourself to have the scroll view perform 342 * scrolling from a key event, just as if the event had been dispatched to 343 * it by the view hierarchy. 344 * 345 * @param event The key event to execute. 346 * @return Return true if the event was handled, else false. 347 */ 348 public boolean executeKeyEvent(KeyEvent event) { 349 mTempRect.setEmpty(); 350 351 if (!canScroll()) { 352 if (isFocused()) { 353 View currentFocused = findFocus(); 354 if (currentFocused == this) currentFocused = null; 355 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 356 currentFocused, View.FOCUS_RIGHT); 357 return nextFocused != null && nextFocused != this && 358 nextFocused.requestFocus(View.FOCUS_RIGHT); 359 } 360 return false; 361 } 362 363 boolean handled = false; 364 if (event.getAction() == KeyEvent.ACTION_DOWN) { 365 switch (event.getKeyCode()) { 366 case KeyEvent.KEYCODE_DPAD_LEFT: 367 if (!event.isAltPressed()) { 368 handled = arrowScroll(View.FOCUS_LEFT); 369 } else { 370 handled = fullScroll(View.FOCUS_LEFT); 371 } 372 break; 373 case KeyEvent.KEYCODE_DPAD_RIGHT: 374 if (!event.isAltPressed()) { 375 handled = arrowScroll(View.FOCUS_RIGHT); 376 } else { 377 handled = fullScroll(View.FOCUS_RIGHT); 378 } 379 break; 380 case KeyEvent.KEYCODE_SPACE: 381 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 382 break; 383 } 384 } 385 386 return handled; 387 } 388 389 private boolean inChild(int x, int y) { 390 if (getChildCount() > 0) { 391 final int scrollX = mScrollX; 392 final View child = getChildAt(0); 393 return !(y < child.getTop() 394 || y >= child.getBottom() 395 || x < child.getLeft() - scrollX 396 || x >= child.getRight() - scrollX); 397 } 398 return false; 399 } 400 401 private void initOrResetVelocityTracker() { 402 if (mVelocityTracker == null) { 403 mVelocityTracker = VelocityTracker.obtain(); 404 } else { 405 mVelocityTracker.clear(); 406 } 407 } 408 409 private void initVelocityTrackerIfNotExists() { 410 if (mVelocityTracker == null) { 411 mVelocityTracker = VelocityTracker.obtain(); 412 } 413 } 414 415 private void recycleVelocityTracker() { 416 if (mVelocityTracker != null) { 417 mVelocityTracker.recycle(); 418 mVelocityTracker = null; 419 } 420 } 421 422 @Override 423 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 424 if (disallowIntercept) { 425 recycleVelocityTracker(); 426 } 427 super.requestDisallowInterceptTouchEvent(disallowIntercept); 428 } 429 430 @Override 431 public boolean onInterceptTouchEvent(MotionEvent ev) { 432 /* 433 * This method JUST determines whether we want to intercept the motion. 434 * If we return true, onMotionEvent will be called and we do the actual 435 * scrolling there. 436 */ 437 438 /* 439 * Shortcut the most recurring case: the user is in the dragging 440 * state and he is moving his finger. We want to intercept this 441 * motion. 442 */ 443 final int action = ev.getAction(); 444 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 445 return true; 446 } 447 448 switch (action & MotionEvent.ACTION_MASK) { 449 case MotionEvent.ACTION_MOVE: { 450 /* 451 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 452 * whether the user has moved far enough from his original down touch. 453 */ 454 455 /* 456 * Locally do absolute value. mLastMotionX is set to the x value 457 * of the down event. 458 */ 459 final int activePointerId = mActivePointerId; 460 if (activePointerId == INVALID_POINTER) { 461 // If we don't have a valid id, the touch down wasn't on content. 462 break; 463 } 464 465 final int pointerIndex = ev.findPointerIndex(activePointerId); 466 if (pointerIndex == -1) { 467 Log.e(TAG, "Invalid pointerId=" + activePointerId 468 + " in onInterceptTouchEvent"); 469 break; 470 } 471 472 final int x = (int) ev.getX(pointerIndex); 473 final int xDiff = (int) Math.abs(x - mLastMotionX); 474 if (xDiff > mTouchSlop) { 475 mIsBeingDragged = true; 476 mLastMotionX = x; 477 initVelocityTrackerIfNotExists(); 478 mVelocityTracker.addMovement(ev); 479 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 480 } 481 break; 482 } 483 484 case MotionEvent.ACTION_DOWN: { 485 final int x = (int) ev.getX(); 486 if (!inChild((int) x, (int) ev.getY())) { 487 mIsBeingDragged = false; 488 recycleVelocityTracker(); 489 break; 490 } 491 492 /* 493 * Remember location of down touch. 494 * ACTION_DOWN always refers to pointer index 0. 495 */ 496 mLastMotionX = x; 497 mActivePointerId = ev.getPointerId(0); 498 499 initOrResetVelocityTracker(); 500 mVelocityTracker.addMovement(ev); 501 502 /* 503 * If being flinged and user touches the screen, initiate drag; 504 * otherwise don't. mScroller.isFinished should be false when 505 * being flinged. 506 */ 507 mIsBeingDragged = !mScroller.isFinished(); 508 break; 509 } 510 511 case MotionEvent.ACTION_CANCEL: 512 case MotionEvent.ACTION_UP: 513 /* Release the drag */ 514 mIsBeingDragged = false; 515 mActivePointerId = INVALID_POINTER; 516 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 517 postInvalidateOnAnimation(); 518 } 519 break; 520 case MotionEvent.ACTION_POINTER_DOWN: { 521 final int index = ev.getActionIndex(); 522 mLastMotionX = (int) ev.getX(index); 523 mActivePointerId = ev.getPointerId(index); 524 break; 525 } 526 case MotionEvent.ACTION_POINTER_UP: 527 onSecondaryPointerUp(ev); 528 mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId)); 529 break; 530 } 531 532 /* 533 * The only time we want to intercept motion events is if we are in the 534 * drag mode. 535 */ 536 return mIsBeingDragged; 537 } 538 539 @Override 540 public boolean onTouchEvent(MotionEvent ev) { 541 initVelocityTrackerIfNotExists(); 542 mVelocityTracker.addMovement(ev); 543 544 final int action = ev.getAction(); 545 546 switch (action & MotionEvent.ACTION_MASK) { 547 case MotionEvent.ACTION_DOWN: { 548 if (getChildCount() == 0) { 549 return false; 550 } 551 if ((mIsBeingDragged = !mScroller.isFinished())) { 552 final ViewParent parent = getParent(); 553 if (parent != null) { 554 parent.requestDisallowInterceptTouchEvent(true); 555 } 556 } 557 558 /* 559 * If being flinged and user touches, stop the fling. isFinished 560 * will be false if being flinged. 561 */ 562 if (!mScroller.isFinished()) { 563 mScroller.abortAnimation(); 564 } 565 566 // Remember where the motion event started 567 mLastMotionX = (int) ev.getX(); 568 mActivePointerId = ev.getPointerId(0); 569 break; 570 } 571 case MotionEvent.ACTION_MOVE: 572 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 573 if (activePointerIndex == -1) { 574 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 575 break; 576 } 577 578 final int x = (int) ev.getX(activePointerIndex); 579 int deltaX = mLastMotionX - x; 580 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 581 final ViewParent parent = getParent(); 582 if (parent != null) { 583 parent.requestDisallowInterceptTouchEvent(true); 584 } 585 mIsBeingDragged = true; 586 if (deltaX > 0) { 587 deltaX -= mTouchSlop; 588 } else { 589 deltaX += mTouchSlop; 590 } 591 } 592 if (mIsBeingDragged) { 593 // Scroll to follow the motion event 594 mLastMotionX = x; 595 596 final int oldX = mScrollX; 597 final int oldY = mScrollY; 598 final int range = getScrollRange(); 599 final int overscrollMode = getOverScrollMode(); 600 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 601 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 602 603 // Calling overScrollBy will call onOverScrolled, which 604 // calls onScrollChanged if applicable. 605 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 606 mOverscrollDistance, 0, true)) { 607 // Break our velocity if we hit a scroll barrier. 608 mVelocityTracker.clear(); 609 } 610 611 if (canOverscroll) { 612 final int pulledToX = oldX + deltaX; 613 if (pulledToX < 0) { 614 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 615 if (!mEdgeGlowRight.isFinished()) { 616 mEdgeGlowRight.onRelease(); 617 } 618 } else if (pulledToX > range) { 619 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 620 if (!mEdgeGlowLeft.isFinished()) { 621 mEdgeGlowLeft.onRelease(); 622 } 623 } 624 if (mEdgeGlowLeft != null 625 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 626 postInvalidateOnAnimation(); 627 } 628 } 629 } 630 break; 631 case MotionEvent.ACTION_UP: 632 if (mIsBeingDragged) { 633 final VelocityTracker velocityTracker = mVelocityTracker; 634 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 635 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 636 637 if (getChildCount() > 0) { 638 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 639 fling(-initialVelocity); 640 } else { 641 if (mScroller.springBack(mScrollX, mScrollY, 0, 642 getScrollRange(), 0, 0)) { 643 postInvalidateOnAnimation(); 644 } 645 } 646 } 647 648 mActivePointerId = INVALID_POINTER; 649 mIsBeingDragged = false; 650 recycleVelocityTracker(); 651 652 if (mEdgeGlowLeft != null) { 653 mEdgeGlowLeft.onRelease(); 654 mEdgeGlowRight.onRelease(); 655 } 656 } 657 break; 658 case MotionEvent.ACTION_CANCEL: 659 if (mIsBeingDragged && getChildCount() > 0) { 660 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 661 postInvalidateOnAnimation(); 662 } 663 mActivePointerId = INVALID_POINTER; 664 mIsBeingDragged = false; 665 recycleVelocityTracker(); 666 667 if (mEdgeGlowLeft != null) { 668 mEdgeGlowLeft.onRelease(); 669 mEdgeGlowRight.onRelease(); 670 } 671 } 672 break; 673 case MotionEvent.ACTION_POINTER_UP: 674 onSecondaryPointerUp(ev); 675 break; 676 } 677 return true; 678 } 679 680 private void onSecondaryPointerUp(MotionEvent ev) { 681 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 682 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 683 final int pointerId = ev.getPointerId(pointerIndex); 684 if (pointerId == mActivePointerId) { 685 // This was our active pointer going up. Choose a new 686 // active pointer and adjust accordingly. 687 // TODO: Make this decision more intelligent. 688 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 689 mLastMotionX = (int) ev.getX(newPointerIndex); 690 mActivePointerId = ev.getPointerId(newPointerIndex); 691 if (mVelocityTracker != null) { 692 mVelocityTracker.clear(); 693 } 694 } 695 } 696 697 @Override 698 public boolean onGenericMotionEvent(MotionEvent event) { 699 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 700 switch (event.getAction()) { 701 case MotionEvent.ACTION_SCROLL: { 702 if (!mIsBeingDragged) { 703 final float hscroll; 704 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 705 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 706 } else { 707 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 708 } 709 if (hscroll != 0) { 710 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 711 final int range = getScrollRange(); 712 int oldScrollX = mScrollX; 713 int newScrollX = oldScrollX + delta; 714 if (newScrollX < 0) { 715 newScrollX = 0; 716 } else if (newScrollX > range) { 717 newScrollX = range; 718 } 719 if (newScrollX != oldScrollX) { 720 super.scrollTo(newScrollX, mScrollY); 721 return true; 722 } 723 } 724 } 725 } 726 } 727 } 728 return super.onGenericMotionEvent(event); 729 } 730 731 @Override 732 public boolean shouldDelayChildPressedState() { 733 return true; 734 } 735 736 @Override 737 protected void onOverScrolled(int scrollX, int scrollY, 738 boolean clampedX, boolean clampedY) { 739 // Treat animating scrolls differently; see #computeScroll() for why. 740 if (!mScroller.isFinished()) { 741 final int oldX = mScrollX; 742 final int oldY = mScrollY; 743 mScrollX = scrollX; 744 mScrollY = scrollY; 745 invalidateParentIfNeeded(); 746 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 747 if (clampedX) { 748 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 749 } 750 } else { 751 super.scrollTo(scrollX, scrollY); 752 } 753 754 awakenScrollBars(); 755 } 756 757 @Override 758 public boolean performAccessibilityAction(int action, Bundle arguments) { 759 if (super.performAccessibilityAction(action, arguments)) { 760 return true; 761 } 762 switch (action) { 763 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 764 if (!isEnabled()) { 765 return false; 766 } 767 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 768 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 769 if (targetScrollX != mScrollX) { 770 smoothScrollTo(targetScrollX, 0); 771 return true; 772 } 773 } return false; 774 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 775 if (!isEnabled()) { 776 return false; 777 } 778 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 779 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 780 if (targetScrollX != mScrollX) { 781 smoothScrollTo(targetScrollX, 0); 782 return true; 783 } 784 } return false; 785 } 786 return false; 787 } 788 789 @Override 790 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 791 super.onInitializeAccessibilityNodeInfo(info); 792 info.setClassName(HorizontalScrollView.class.getName()); 793 final int scrollRange = getScrollRange(); 794 if (scrollRange > 0) { 795 info.setScrollable(true); 796 if (isEnabled() && mScrollX > 0) { 797 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 798 } 799 if (isEnabled() && mScrollX < scrollRange) { 800 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 801 } 802 } 803 } 804 805 @Override 806 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 807 super.onInitializeAccessibilityEvent(event); 808 event.setClassName(HorizontalScrollView.class.getName()); 809 event.setScrollable(getScrollRange() > 0); 810 event.setScrollX(mScrollX); 811 event.setScrollY(mScrollY); 812 event.setMaxScrollX(getScrollRange()); 813 event.setMaxScrollY(mScrollY); 814 } 815 816 private int getScrollRange() { 817 int scrollRange = 0; 818 if (getChildCount() > 0) { 819 View child = getChildAt(0); 820 scrollRange = Math.max(0, 821 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 822 } 823 return scrollRange; 824 } 825 826 /** 827 * <p> 828 * Finds the next focusable component that fits in this View's bounds 829 * (excluding fading edges) pretending that this View's left is located at 830 * the parameter left. 831 * </p> 832 * 833 * @param leftFocus look for a candidate is the one at the left of the bounds 834 * if leftFocus is true, or at the right of the bounds if leftFocus 835 * is false 836 * @param left the left offset of the bounds in which a focusable must be 837 * found (the fading edge is assumed to start at this position) 838 * @param preferredFocusable the View that has highest priority and will be 839 * returned if it is within my bounds (null is valid) 840 * @return the next focusable component in the bounds or null if none can be found 841 */ 842 private View findFocusableViewInMyBounds(final boolean leftFocus, 843 final int left, View preferredFocusable) { 844 /* 845 * The fading edge's transparent side should be considered for focus 846 * since it's mostly visible, so we divide the actual fading edge length 847 * by 2. 848 */ 849 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 850 final int leftWithoutFadingEdge = left + fadingEdgeLength; 851 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 852 853 if ((preferredFocusable != null) 854 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 855 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 856 return preferredFocusable; 857 } 858 859 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 860 rightWithoutFadingEdge); 861 } 862 863 /** 864 * <p> 865 * Finds the next focusable component that fits in the specified bounds. 866 * </p> 867 * 868 * @param leftFocus look for a candidate is the one at the left of the bounds 869 * if leftFocus is true, or at the right of the bounds if 870 * leftFocus is false 871 * @param left the left offset of the bounds in which a focusable must be 872 * found 873 * @param right the right offset of the bounds in which a focusable must 874 * be found 875 * @return the next focusable component in the bounds or null if none can 876 * be found 877 */ 878 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 879 880 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 881 View focusCandidate = null; 882 883 /* 884 * A fully contained focusable is one where its left is below the bound's 885 * left, and its right is above the bound's right. A partially 886 * contained focusable is one where some part of it is within the 887 * bounds, but it also has some part that is not within bounds. A fully contained 888 * focusable is preferred to a partially contained focusable. 889 */ 890 boolean foundFullyContainedFocusable = false; 891 892 int count = focusables.size(); 893 for (int i = 0; i < count; i++) { 894 View view = focusables.get(i); 895 int viewLeft = view.getLeft(); 896 int viewRight = view.getRight(); 897 898 if (left < viewRight && viewLeft < right) { 899 /* 900 * the focusable is in the target area, it is a candidate for 901 * focusing 902 */ 903 904 final boolean viewIsFullyContained = (left < viewLeft) && 905 (viewRight < right); 906 907 if (focusCandidate == null) { 908 /* No candidate, take this one */ 909 focusCandidate = view; 910 foundFullyContainedFocusable = viewIsFullyContained; 911 } else { 912 final boolean viewIsCloserToBoundary = 913 (leftFocus && viewLeft < focusCandidate.getLeft()) || 914 (!leftFocus && viewRight > focusCandidate.getRight()); 915 916 if (foundFullyContainedFocusable) { 917 if (viewIsFullyContained && viewIsCloserToBoundary) { 918 /* 919 * We're dealing with only fully contained views, so 920 * it has to be closer to the boundary to beat our 921 * candidate 922 */ 923 focusCandidate = view; 924 } 925 } else { 926 if (viewIsFullyContained) { 927 /* Any fully contained view beats a partially contained view */ 928 focusCandidate = view; 929 foundFullyContainedFocusable = true; 930 } else if (viewIsCloserToBoundary) { 931 /* 932 * Partially contained view beats another partially 933 * contained view if it's closer 934 */ 935 focusCandidate = view; 936 } 937 } 938 } 939 } 940 } 941 942 return focusCandidate; 943 } 944 945 /** 946 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 947 * method will scroll the view by one page left or right and give the focus 948 * to the leftmost/rightmost component in the new visible area. If no 949 * component is a good candidate for focus, this scrollview reclaims the 950 * focus.</p> 951 * 952 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 953 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 954 * to go one page right 955 * @return true if the key event is consumed by this method, false otherwise 956 */ 957 public boolean pageScroll(int direction) { 958 boolean right = direction == View.FOCUS_RIGHT; 959 int width = getWidth(); 960 961 if (right) { 962 mTempRect.left = getScrollX() + width; 963 int count = getChildCount(); 964 if (count > 0) { 965 View view = getChildAt(0); 966 if (mTempRect.left + width > view.getRight()) { 967 mTempRect.left = view.getRight() - width; 968 } 969 } 970 } else { 971 mTempRect.left = getScrollX() - width; 972 if (mTempRect.left < 0) { 973 mTempRect.left = 0; 974 } 975 } 976 mTempRect.right = mTempRect.left + width; 977 978 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 979 } 980 981 /** 982 * <p>Handles scrolling in response to a "home/end" shortcut press. This 983 * method will scroll the view to the left or right and give the focus 984 * to the leftmost/rightmost component in the new visible area. If no 985 * component is a good candidate for focus, this scrollview reclaims the 986 * focus.</p> 987 * 988 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 989 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 990 * to go the right 991 * @return true if the key event is consumed by this method, false otherwise 992 */ 993 public boolean fullScroll(int direction) { 994 boolean right = direction == View.FOCUS_RIGHT; 995 int width = getWidth(); 996 997 mTempRect.left = 0; 998 mTempRect.right = width; 999 1000 if (right) { 1001 int count = getChildCount(); 1002 if (count > 0) { 1003 View view = getChildAt(0); 1004 mTempRect.right = view.getRight(); 1005 mTempRect.left = mTempRect.right - width; 1006 } 1007 } 1008 1009 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 1010 } 1011 1012 /** 1013 * <p>Scrolls the view to make the area defined by <code>left</code> and 1014 * <code>right</code> visible. This method attempts to give the focus 1015 * to a component visible in this area. If no component can be focused in 1016 * the new visible area, the focus is reclaimed by this scrollview.</p> 1017 * 1018 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1019 * to go left {@link android.view.View#FOCUS_RIGHT} to right 1020 * @param left the left offset of the new area to be made visible 1021 * @param right the right offset of the new area to be made visible 1022 * @return true if the key event is consumed by this method, false otherwise 1023 */ 1024 private boolean scrollAndFocus(int direction, int left, int right) { 1025 boolean handled = true; 1026 1027 int width = getWidth(); 1028 int containerLeft = getScrollX(); 1029 int containerRight = containerLeft + width; 1030 boolean goLeft = direction == View.FOCUS_LEFT; 1031 1032 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1033 if (newFocused == null) { 1034 newFocused = this; 1035 } 1036 1037 if (left >= containerLeft && right <= containerRight) { 1038 handled = false; 1039 } else { 1040 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1041 doScrollX(delta); 1042 } 1043 1044 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1045 1046 return handled; 1047 } 1048 1049 /** 1050 * Handle scrolling in response to a left or right arrow click. 1051 * 1052 * @param direction The direction corresponding to the arrow key that was 1053 * pressed 1054 * @return True if we consumed the event, false otherwise 1055 */ 1056 public boolean arrowScroll(int direction) { 1057 1058 View currentFocused = findFocus(); 1059 if (currentFocused == this) currentFocused = null; 1060 1061 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1062 1063 final int maxJump = getMaxScrollAmount(); 1064 1065 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1066 nextFocused.getDrawingRect(mTempRect); 1067 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1068 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1069 doScrollX(scrollDelta); 1070 nextFocused.requestFocus(direction); 1071 } else { 1072 // no new focus 1073 int scrollDelta = maxJump; 1074 1075 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1076 scrollDelta = getScrollX(); 1077 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1078 1079 int daRight = getChildAt(0).getRight(); 1080 1081 int screenRight = getScrollX() + getWidth(); 1082 1083 if (daRight - screenRight < maxJump) { 1084 scrollDelta = daRight - screenRight; 1085 } 1086 } 1087 if (scrollDelta == 0) { 1088 return false; 1089 } 1090 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1091 } 1092 1093 if (currentFocused != null && currentFocused.isFocused() 1094 && isOffScreen(currentFocused)) { 1095 // previously focused item still has focus and is off screen, give 1096 // it up (take it back to ourselves) 1097 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1098 // sure to 1099 // get it) 1100 final int descendantFocusability = getDescendantFocusability(); // save 1101 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1102 requestFocus(); 1103 setDescendantFocusability(descendantFocusability); // restore 1104 } 1105 return true; 1106 } 1107 1108 /** 1109 * @return whether the descendant of this scroll view is scrolled off 1110 * screen. 1111 */ 1112 private boolean isOffScreen(View descendant) { 1113 return !isWithinDeltaOfScreen(descendant, 0); 1114 } 1115 1116 /** 1117 * @return whether the descendant of this scroll view is within delta 1118 * pixels of being on the screen. 1119 */ 1120 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1121 descendant.getDrawingRect(mTempRect); 1122 offsetDescendantRectToMyCoords(descendant, mTempRect); 1123 1124 return (mTempRect.right + delta) >= getScrollX() 1125 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1126 } 1127 1128 /** 1129 * Smooth scroll by a X delta 1130 * 1131 * @param delta the number of pixels to scroll by on the X axis 1132 */ 1133 private void doScrollX(int delta) { 1134 if (delta != 0) { 1135 if (mSmoothScrollingEnabled) { 1136 smoothScrollBy(delta, 0); 1137 } else { 1138 scrollBy(delta, 0); 1139 } 1140 } 1141 } 1142 1143 /** 1144 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1145 * 1146 * @param dx the number of pixels to scroll by on the X axis 1147 * @param dy the number of pixels to scroll by on the Y axis 1148 */ 1149 public final void smoothScrollBy(int dx, int dy) { 1150 if (getChildCount() == 0) { 1151 // Nothing to do. 1152 return; 1153 } 1154 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1155 if (duration > ANIMATED_SCROLL_GAP) { 1156 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1157 final int right = getChildAt(0).getWidth(); 1158 final int maxX = Math.max(0, right - width); 1159 final int scrollX = mScrollX; 1160 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1161 1162 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1163 postInvalidateOnAnimation(); 1164 } else { 1165 if (!mScroller.isFinished()) { 1166 mScroller.abortAnimation(); 1167 } 1168 scrollBy(dx, dy); 1169 } 1170 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1171 } 1172 1173 /** 1174 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1175 * 1176 * @param x the position where to scroll on the X axis 1177 * @param y the position where to scroll on the Y axis 1178 */ 1179 public final void smoothScrollTo(int x, int y) { 1180 smoothScrollBy(x - mScrollX, y - mScrollY); 1181 } 1182 1183 /** 1184 * <p>The scroll range of a scroll view is the overall width of all of its 1185 * children.</p> 1186 */ 1187 @Override 1188 protected int computeHorizontalScrollRange() { 1189 final int count = getChildCount(); 1190 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1191 if (count == 0) { 1192 return contentWidth; 1193 } 1194 1195 int scrollRange = getChildAt(0).getRight(); 1196 final int scrollX = mScrollX; 1197 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1198 if (scrollX < 0) { 1199 scrollRange -= scrollX; 1200 } else if (scrollX > overscrollRight) { 1201 scrollRange += scrollX - overscrollRight; 1202 } 1203 1204 return scrollRange; 1205 } 1206 1207 @Override 1208 protected int computeHorizontalScrollOffset() { 1209 return Math.max(0, super.computeHorizontalScrollOffset()); 1210 } 1211 1212 @Override 1213 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1214 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1215 1216 int childWidthMeasureSpec; 1217 int childHeightMeasureSpec; 1218 1219 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1220 + mPaddingBottom, lp.height); 1221 1222 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1223 1224 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1225 } 1226 1227 @Override 1228 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1229 int parentHeightMeasureSpec, int heightUsed) { 1230 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1231 1232 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1233 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1234 + heightUsed, lp.height); 1235 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1236 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1237 1238 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1239 } 1240 1241 @Override 1242 public void computeScroll() { 1243 if (mScroller.computeScrollOffset()) { 1244 // This is called at drawing time by ViewGroup. We don't want to 1245 // re-show the scrollbars at this point, which scrollTo will do, 1246 // so we replicate most of scrollTo here. 1247 // 1248 // It's a little odd to call onScrollChanged from inside the drawing. 1249 // 1250 // It is, except when you remember that computeScroll() is used to 1251 // animate scrolling. So unless we want to defer the onScrollChanged() 1252 // until the end of the animated scrolling, we don't really have a 1253 // choice here. 1254 // 1255 // I agree. The alternative, which I think would be worse, is to post 1256 // something and tell the subclasses later. This is bad because there 1257 // will be a window where mScrollX/Y is different from what the app 1258 // thinks it is. 1259 // 1260 int oldX = mScrollX; 1261 int oldY = mScrollY; 1262 int x = mScroller.getCurrX(); 1263 int y = mScroller.getCurrY(); 1264 1265 if (oldX != x || oldY != y) { 1266 final int range = getScrollRange(); 1267 final int overscrollMode = getOverScrollMode(); 1268 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1269 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1270 1271 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1272 mOverflingDistance, 0, false); 1273 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1274 1275 if (canOverscroll) { 1276 if (x < 0 && oldX >= 0) { 1277 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1278 } else if (x > range && oldX <= range) { 1279 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1280 } 1281 } 1282 } 1283 1284 if (!awakenScrollBars()) { 1285 postInvalidateOnAnimation(); 1286 } 1287 } 1288 } 1289 1290 /** 1291 * Scrolls the view to the given child. 1292 * 1293 * @param child the View to scroll to 1294 */ 1295 private void scrollToChild(View child) { 1296 child.getDrawingRect(mTempRect); 1297 1298 /* Offset from child's local coordinates to ScrollView coordinates */ 1299 offsetDescendantRectToMyCoords(child, mTempRect); 1300 1301 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1302 1303 if (scrollDelta != 0) { 1304 scrollBy(scrollDelta, 0); 1305 } 1306 } 1307 1308 /** 1309 * If rect is off screen, scroll just enough to get it (or at least the 1310 * first screen size chunk of it) on screen. 1311 * 1312 * @param rect The rectangle. 1313 * @param immediate True to scroll immediately without animation 1314 * @return true if scrolling was performed 1315 */ 1316 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1317 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1318 final boolean scroll = delta != 0; 1319 if (scroll) { 1320 if (immediate) { 1321 scrollBy(delta, 0); 1322 } else { 1323 smoothScrollBy(delta, 0); 1324 } 1325 } 1326 return scroll; 1327 } 1328 1329 /** 1330 * Compute the amount to scroll in the X direction in order to get 1331 * a rectangle completely on the screen (or, if taller than the screen, 1332 * at least the first screen size chunk of it). 1333 * 1334 * @param rect The rect. 1335 * @return The scroll delta. 1336 */ 1337 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1338 if (getChildCount() == 0) return 0; 1339 1340 int width = getWidth(); 1341 int screenLeft = getScrollX(); 1342 int screenRight = screenLeft + width; 1343 1344 int fadingEdge = getHorizontalFadingEdgeLength(); 1345 1346 // leave room for left fading edge as long as rect isn't at very left 1347 if (rect.left > 0) { 1348 screenLeft += fadingEdge; 1349 } 1350 1351 // leave room for right fading edge as long as rect isn't at very right 1352 if (rect.right < getChildAt(0).getWidth()) { 1353 screenRight -= fadingEdge; 1354 } 1355 1356 int scrollXDelta = 0; 1357 1358 if (rect.right > screenRight && rect.left > screenLeft) { 1359 // need to move right to get it in view: move right just enough so 1360 // that the entire rectangle is in view (or at least the first 1361 // screen size chunk). 1362 1363 if (rect.width() > width) { 1364 // just enough to get screen size chunk on 1365 scrollXDelta += (rect.left - screenLeft); 1366 } else { 1367 // get entire rect at right of screen 1368 scrollXDelta += (rect.right - screenRight); 1369 } 1370 1371 // make sure we aren't scrolling beyond the end of our content 1372 int right = getChildAt(0).getRight(); 1373 int distanceToRight = right - screenRight; 1374 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1375 1376 } else if (rect.left < screenLeft && rect.right < screenRight) { 1377 // need to move right to get it in view: move right just enough so that 1378 // entire rectangle is in view (or at least the first screen 1379 // size chunk of it). 1380 1381 if (rect.width() > width) { 1382 // screen size chunk 1383 scrollXDelta -= (screenRight - rect.right); 1384 } else { 1385 // entire rect at left 1386 scrollXDelta -= (screenLeft - rect.left); 1387 } 1388 1389 // make sure we aren't scrolling any further than the left our content 1390 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1391 } 1392 return scrollXDelta; 1393 } 1394 1395 @Override 1396 public void requestChildFocus(View child, View focused) { 1397 if (!mIsLayoutDirty) { 1398 scrollToChild(focused); 1399 } else { 1400 // The child may not be laid out yet, we can't compute the scroll yet 1401 mChildToScrollTo = focused; 1402 } 1403 super.requestChildFocus(child, focused); 1404 } 1405 1406 1407 /** 1408 * When looking for focus in children of a scroll view, need to be a little 1409 * more careful not to give focus to something that is scrolled off screen. 1410 * 1411 * This is more expensive than the default {@link android.view.ViewGroup} 1412 * implementation, otherwise this behavior might have been made the default. 1413 */ 1414 @Override 1415 protected boolean onRequestFocusInDescendants(int direction, 1416 Rect previouslyFocusedRect) { 1417 1418 // convert from forward / backward notation to up / down / left / right 1419 // (ugh). 1420 if (direction == View.FOCUS_FORWARD) { 1421 direction = View.FOCUS_RIGHT; 1422 } else if (direction == View.FOCUS_BACKWARD) { 1423 direction = View.FOCUS_LEFT; 1424 } 1425 1426 final View nextFocus = previouslyFocusedRect == null ? 1427 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1428 FocusFinder.getInstance().findNextFocusFromRect(this, 1429 previouslyFocusedRect, direction); 1430 1431 if (nextFocus == null) { 1432 return false; 1433 } 1434 1435 if (isOffScreen(nextFocus)) { 1436 return false; 1437 } 1438 1439 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1440 } 1441 1442 @Override 1443 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1444 boolean immediate) { 1445 // offset into coordinate space of this scroll view 1446 rectangle.offset(child.getLeft() - child.getScrollX(), 1447 child.getTop() - child.getScrollY()); 1448 1449 return scrollToChildRect(rectangle, immediate); 1450 } 1451 1452 @Override 1453 public void requestLayout() { 1454 mIsLayoutDirty = true; 1455 super.requestLayout(); 1456 } 1457 1458 @Override 1459 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1460 int childWidth = 0; 1461 int childMargins = 0; 1462 1463 if (getChildCount() > 0) { 1464 childWidth = getChildAt(0).getMeasuredWidth(); 1465 LayoutParams childParams = (LayoutParams) getChildAt(0).getLayoutParams(); 1466 childMargins = childParams.leftMargin + childParams.rightMargin; 1467 } 1468 1469 final int available = r - l - getPaddingLeftWithForeground() - 1470 getPaddingRightWithForeground() - childMargins; 1471 1472 final boolean forceLeftGravity = (childWidth > available); 1473 1474 layoutChildren(l, t, r, b, forceLeftGravity); 1475 1476 mIsLayoutDirty = false; 1477 // Give a child focus if it needs it 1478 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1479 scrollToChild(mChildToScrollTo); 1480 } 1481 mChildToScrollTo = null; 1482 1483 if (!isLaidOut()) { 1484 final int scrollRange = Math.max(0, 1485 childWidth - (r - l - mPaddingLeft - mPaddingRight)); 1486 if (mSavedState != null) { 1487 if (isLayoutRtl() == mSavedState.isLayoutRtl) { 1488 mScrollX = mSavedState.scrollPosition; 1489 } else { 1490 mScrollX = scrollRange - mSavedState.scrollPosition; 1491 } 1492 mSavedState = null; 1493 } else { 1494 if (isLayoutRtl()) { 1495 mScrollX = scrollRange - mScrollX; 1496 } // mScrollX default value is "0" for LTR 1497 } 1498 // Don't forget to clamp 1499 if (mScrollX > scrollRange) { 1500 mScrollX = scrollRange; 1501 } else if (mScrollX < 0) { 1502 mScrollX = 0; 1503 } 1504 } 1505 1506 // Calling this with the present values causes it to re-claim them 1507 scrollTo(mScrollX, mScrollY); 1508 } 1509 1510 @Override 1511 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1512 super.onSizeChanged(w, h, oldw, oldh); 1513 1514 View currentFocused = findFocus(); 1515 if (null == currentFocused || this == currentFocused) 1516 return; 1517 1518 final int maxJump = mRight - mLeft; 1519 1520 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1521 currentFocused.getDrawingRect(mTempRect); 1522 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1523 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1524 doScrollX(scrollDelta); 1525 } 1526 } 1527 1528 /** 1529 * Return true if child is a descendant of parent, (or equal to the parent). 1530 */ 1531 private static boolean isViewDescendantOf(View child, View parent) { 1532 if (child == parent) { 1533 return true; 1534 } 1535 1536 final ViewParent theParent = child.getParent(); 1537 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1538 } 1539 1540 /** 1541 * Fling the scroll view 1542 * 1543 * @param velocityX The initial velocity in the X direction. Positive 1544 * numbers mean that the finger/cursor is moving down the screen, 1545 * which means we want to scroll towards the left. 1546 */ 1547 public void fling(int velocityX) { 1548 if (getChildCount() > 0) { 1549 int width = getWidth() - mPaddingRight - mPaddingLeft; 1550 int right = getChildAt(0).getWidth(); 1551 1552 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1553 Math.max(0, right - width), 0, 0, width/2, 0); 1554 1555 final boolean movingRight = velocityX > 0; 1556 1557 View currentFocused = findFocus(); 1558 View newFocused = findFocusableViewInMyBounds(movingRight, 1559 mScroller.getFinalX(), currentFocused); 1560 1561 if (newFocused == null) { 1562 newFocused = this; 1563 } 1564 1565 if (newFocused != currentFocused) { 1566 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1567 } 1568 1569 postInvalidateOnAnimation(); 1570 } 1571 } 1572 1573 /** 1574 * {@inheritDoc} 1575 * 1576 * <p>This version also clamps the scrolling to the bounds of our child. 1577 */ 1578 @Override 1579 public void scrollTo(int x, int y) { 1580 // we rely on the fact the View.scrollBy calls scrollTo. 1581 if (getChildCount() > 0) { 1582 View child = getChildAt(0); 1583 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1584 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1585 if (x != mScrollX || y != mScrollY) { 1586 super.scrollTo(x, y); 1587 } 1588 } 1589 } 1590 1591 @Override 1592 public void setOverScrollMode(int mode) { 1593 if (mode != OVER_SCROLL_NEVER) { 1594 if (mEdgeGlowLeft == null) { 1595 Context context = getContext(); 1596 mEdgeGlowLeft = new EdgeEffect(context); 1597 mEdgeGlowRight = new EdgeEffect(context); 1598 } 1599 } else { 1600 mEdgeGlowLeft = null; 1601 mEdgeGlowRight = null; 1602 } 1603 super.setOverScrollMode(mode); 1604 } 1605 1606 @SuppressWarnings({"SuspiciousNameCombination"}) 1607 @Override 1608 public void draw(Canvas canvas) { 1609 super.draw(canvas); 1610 if (mEdgeGlowLeft != null) { 1611 final int scrollX = mScrollX; 1612 if (!mEdgeGlowLeft.isFinished()) { 1613 final int restoreCount = canvas.save(); 1614 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1615 1616 canvas.rotate(270); 1617 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1618 mEdgeGlowLeft.setSize(height, getWidth()); 1619 if (mEdgeGlowLeft.draw(canvas)) { 1620 postInvalidateOnAnimation(); 1621 } 1622 canvas.restoreToCount(restoreCount); 1623 } 1624 if (!mEdgeGlowRight.isFinished()) { 1625 final int restoreCount = canvas.save(); 1626 final int width = getWidth(); 1627 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1628 1629 canvas.rotate(90); 1630 canvas.translate(-mPaddingTop, 1631 -(Math.max(getScrollRange(), scrollX) + width)); 1632 mEdgeGlowRight.setSize(height, width); 1633 if (mEdgeGlowRight.draw(canvas)) { 1634 postInvalidateOnAnimation(); 1635 } 1636 canvas.restoreToCount(restoreCount); 1637 } 1638 } 1639 } 1640 1641 private static int clamp(int n, int my, int child) { 1642 if (my >= child || n < 0) { 1643 return 0; 1644 } 1645 if ((my + n) > child) { 1646 return child - my; 1647 } 1648 return n; 1649 } 1650 1651 @Override 1652 protected void onRestoreInstanceState(Parcelable state) { 1653 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1654 // Some old apps reused IDs in ways they shouldn't have. 1655 // Don't break them, but they don't get scroll state restoration. 1656 super.onRestoreInstanceState(state); 1657 return; 1658 } 1659 SavedState ss = (SavedState) state; 1660 super.onRestoreInstanceState(ss.getSuperState()); 1661 mSavedState = ss; 1662 requestLayout(); 1663 } 1664 1665 @Override 1666 protected Parcelable onSaveInstanceState() { 1667 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1668 // Some old apps reused IDs in ways they shouldn't have. 1669 // Don't break them, but they don't get scroll state restoration. 1670 return super.onSaveInstanceState(); 1671 } 1672 Parcelable superState = super.onSaveInstanceState(); 1673 SavedState ss = new SavedState(superState); 1674 ss.scrollPosition = mScrollX; 1675 ss.isLayoutRtl = isLayoutRtl(); 1676 return ss; 1677 } 1678 1679 static class SavedState extends BaseSavedState { 1680 public int scrollPosition; 1681 public boolean isLayoutRtl; 1682 1683 SavedState(Parcelable superState) { 1684 super(superState); 1685 } 1686 1687 public SavedState(Parcel source) { 1688 super(source); 1689 scrollPosition = source.readInt(); 1690 isLayoutRtl = (source.readInt() == 0) ? true : false; 1691 } 1692 1693 @Override 1694 public void writeToParcel(Parcel dest, int flags) { 1695 super.writeToParcel(dest, flags); 1696 dest.writeInt(scrollPosition); 1697 dest.writeInt(isLayoutRtl ? 1 : 0); 1698 } 1699 1700 @Override 1701 public String toString() { 1702 return "HorizontalScrollView.SavedState{" 1703 + Integer.toHexString(System.identityHashCode(this)) 1704 + " scrollPosition=" + scrollPosition 1705 + " isLayoutRtl=" + isLayoutRtl + "}"; 1706 } 1707 1708 public static final Parcelable.Creator<SavedState> CREATOR 1709 = new Parcelable.Creator<SavedState>() { 1710 public SavedState createFromParcel(Parcel in) { 1711 return new SavedState(in); 1712 } 1713 1714 public SavedState[] newArray(int size) { 1715 return new SavedState[size]; 1716 } 1717 }; 1718 } 1719 } 1720
