HorizontalScrollView.java revision f2fb76cc23e18f7b15f7244e6352d024b5008f38
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.widget; 18 19import android.content.Context; 20import android.content.res.TypedArray; 21import android.graphics.Canvas; 22import android.graphics.Rect; 23import android.os.Bundle; 24import android.os.Parcel; 25import android.os.Parcelable; 26import android.util.AttributeSet; 27import android.util.Log; 28import android.view.FocusFinder; 29import android.view.InputDevice; 30import android.view.KeyEvent; 31import android.view.MotionEvent; 32import android.view.VelocityTracker; 33import android.view.View; 34import android.view.ViewConfiguration; 35import android.view.ViewDebug; 36import android.view.ViewGroup; 37import android.view.ViewParent; 38import android.view.accessibility.AccessibilityEvent; 39import android.view.accessibility.AccessibilityNodeInfo; 40import android.view.animation.AnimationUtils; 41 42import java.util.List; 43 44/** 45 * Layout container for a view hierarchy that can be scrolled by the user, 46 * allowing it to be larger than the physical display. A HorizontalScrollView 47 * is a {@link FrameLayout}, meaning you should place one child in it 48 * containing the entire contents to scroll; this child may itself be a layout 49 * manager with a complex hierarchy of objects. A child that is often used 50 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 51 * array of top-level items that the user can scroll through. 52 * 53 * <p>The {@link TextView} class also 54 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 55 * using the two together is possible to achieve the effect of a text view 56 * within a larger container. 57 * 58 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 59 * use either {@link ScrollView} or {@link ListView}. 60 * 61 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 62 */ 63public class HorizontalScrollView extends FrameLayout { 64 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 65 66 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 67 68 private static final String TAG = "HorizontalScrollView"; 69 70 private long mLastScroll; 71 72 private final Rect mTempRect = new Rect(); 73 private OverScroller mScroller; 74 private EdgeEffect mEdgeGlowLeft; 75 private EdgeEffect mEdgeGlowRight; 76 77 /** 78 * Position of the last motion event. 79 */ 80 private int mLastMotionX; 81 82 /** 83 * True when the layout has changed but the traversal has not come through yet. 84 * Ideally the view hierarchy would keep track of this for us. 85 */ 86 private boolean mIsLayoutDirty = true; 87 88 /** 89 * The child to give focus to in the event that a child has requested focus while the 90 * layout is dirty. This prevents the scroll from being wrong if the child has not been 91 * laid out before requesting focus. 92 */ 93 private View mChildToScrollTo = null; 94 95 /** 96 * True if the user is currently dragging this ScrollView around. This is 97 * not the same as 'is being flinged', which can be checked by 98 * mScroller.isFinished() (flinging begins when the user lifts his finger). 99 */ 100 private boolean mIsBeingDragged = false; 101 102 /** 103 * Determines speed during touch scrolling 104 */ 105 private VelocityTracker mVelocityTracker; 106 107 /** 108 * When set to true, the scroll view measure its child to make it fill the currently 109 * visible area. 110 */ 111 @ViewDebug.ExportedProperty(category = "layout") 112 private boolean mFillViewport; 113 114 /** 115 * Whether arrow scrolling is animated. 116 */ 117 private boolean mSmoothScrollingEnabled = true; 118 119 private int mTouchSlop; 120 private int mMinimumVelocity; 121 private int mMaximumVelocity; 122 123 private int mOverscrollDistance; 124 private int mOverflingDistance; 125 126 /** 127 * ID of the active pointer. This is used to retain consistency during 128 * drags/flings if multiple pointers are used. 129 */ 130 private int mActivePointerId = INVALID_POINTER; 131 132 /** 133 * Sentinel value for no current active pointer. 134 * Used by {@link #mActivePointerId}. 135 */ 136 private static final int INVALID_POINTER = -1; 137 138 private SavedState mSavedState; 139 140 public HorizontalScrollView(Context context) { 141 this(context, null); 142 } 143 144 public HorizontalScrollView(Context context, AttributeSet attrs) { 145 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 146 } 147 148 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 149 super(context, attrs, defStyle); 150 initScrollView(); 151 152 TypedArray a = context.obtainStyledAttributes(attrs, 153 android.R.styleable.HorizontalScrollView, defStyle, 0); 154 155 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 156 157 a.recycle(); 158 } 159 160 @Override 161 protected float getLeftFadingEdgeStrength() { 162 if (getChildCount() == 0) { 163 return 0.0f; 164 } 165 166 final int length = getHorizontalFadingEdgeLength(); 167 if (mScrollX < length) { 168 return mScrollX / (float) length; 169 } 170 171 return 1.0f; 172 } 173 174 @Override 175 protected float getRightFadingEdgeStrength() { 176 if (getChildCount() == 0) { 177 return 0.0f; 178 } 179 180 final int length = getHorizontalFadingEdgeLength(); 181 final int rightEdge = getWidth() - mPaddingRight; 182 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 183 if (span < length) { 184 return span / (float) length; 185 } 186 187 return 1.0f; 188 } 189 190 /** 191 * @return The maximum amount this scroll view will scroll in response to 192 * an arrow event. 193 */ 194 public int getMaxScrollAmount() { 195 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 196 } 197 198 199 private void initScrollView() { 200 mScroller = new OverScroller(getContext()); 201 setFocusable(true); 202 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 203 setWillNotDraw(false); 204 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 205 mTouchSlop = configuration.getScaledTouchSlop(); 206 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 207 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 208 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 209 mOverflingDistance = configuration.getScaledOverflingDistance(); 210 } 211 212 @Override 213 public void addView(View child) { 214 if (getChildCount() > 0) { 215 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 216 } 217 218 super.addView(child); 219 } 220 221 @Override 222 public void addView(View child, int index) { 223 if (getChildCount() > 0) { 224 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 225 } 226 227 super.addView(child, index); 228 } 229 230 @Override 231 public void addView(View child, ViewGroup.LayoutParams params) { 232 if (getChildCount() > 0) { 233 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 234 } 235 236 super.addView(child, params); 237 } 238 239 @Override 240 public void addView(View child, int index, ViewGroup.LayoutParams params) { 241 if (getChildCount() > 0) { 242 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 243 } 244 245 super.addView(child, index, params); 246 } 247 248 /** 249 * @return Returns true this HorizontalScrollView can be scrolled 250 */ 251 private boolean canScroll() { 252 View child = getChildAt(0); 253 if (child != null) { 254 int childWidth = child.getWidth(); 255 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 256 } 257 return false; 258 } 259 260 /** 261 * Indicates whether this HorizontalScrollView's content is stretched to 262 * fill the viewport. 263 * 264 * @return True if the content fills the viewport, false otherwise. 265 * 266 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 267 */ 268 public boolean isFillViewport() { 269 return mFillViewport; 270 } 271 272 /** 273 * Indicates this HorizontalScrollView whether it should stretch its content width 274 * to fill the viewport or not. 275 * 276 * @param fillViewport True to stretch the content's width to the viewport's 277 * boundaries, false otherwise. 278 * 279 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 280 */ 281 public void setFillViewport(boolean fillViewport) { 282 if (fillViewport != mFillViewport) { 283 mFillViewport = fillViewport; 284 requestLayout(); 285 } 286 } 287 288 /** 289 * @return Whether arrow scrolling will animate its transition. 290 */ 291 public boolean isSmoothScrollingEnabled() { 292 return mSmoothScrollingEnabled; 293 } 294 295 /** 296 * Set whether arrow scrolling will animate its transition. 297 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 298 */ 299 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 300 mSmoothScrollingEnabled = smoothScrollingEnabled; 301 } 302 303 @Override 304 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 305 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 306 307 if (!mFillViewport) { 308 return; 309 } 310 311 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 312 if (widthMode == MeasureSpec.UNSPECIFIED) { 313 return; 314 } 315 316 if (getChildCount() > 0) { 317 final View child = getChildAt(0); 318 int width = getMeasuredWidth(); 319 if (child.getMeasuredWidth() < width) { 320 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 321 322 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 323 + mPaddingBottom, lp.height); 324 width -= mPaddingLeft; 325 width -= mPaddingRight; 326 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 327 328 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 329 } 330 } 331 } 332 333 @Override 334 public boolean dispatchKeyEvent(KeyEvent event) { 335 // Let the focused view and/or our descendants get the key first 336 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 337 } 338 339 /** 340 * You can call this function yourself to have the scroll view perform 341 * scrolling from a key event, just as if the event had been dispatched to 342 * it by the view hierarchy. 343 * 344 * @param event The key event to execute. 345 * @return Return true if the event was handled, else false. 346 */ 347 public boolean executeKeyEvent(KeyEvent event) { 348 mTempRect.setEmpty(); 349 350 if (!canScroll()) { 351 if (isFocused()) { 352 View currentFocused = findFocus(); 353 if (currentFocused == this) currentFocused = null; 354 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 355 currentFocused, View.FOCUS_RIGHT); 356 return nextFocused != null && nextFocused != this && 357 nextFocused.requestFocus(View.FOCUS_RIGHT); 358 } 359 return false; 360 } 361 362 boolean handled = false; 363 if (event.getAction() == KeyEvent.ACTION_DOWN) { 364 switch (event.getKeyCode()) { 365 case KeyEvent.KEYCODE_DPAD_LEFT: 366 if (!event.isAltPressed()) { 367 handled = arrowScroll(View.FOCUS_LEFT); 368 } else { 369 handled = fullScroll(View.FOCUS_LEFT); 370 } 371 break; 372 case KeyEvent.KEYCODE_DPAD_RIGHT: 373 if (!event.isAltPressed()) { 374 handled = arrowScroll(View.FOCUS_RIGHT); 375 } else { 376 handled = fullScroll(View.FOCUS_RIGHT); 377 } 378 break; 379 case KeyEvent.KEYCODE_SPACE: 380 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 381 break; 382 } 383 } 384 385 return handled; 386 } 387 388 private boolean inChild(int x, int y) { 389 if (getChildCount() > 0) { 390 final int scrollX = mScrollX; 391 final View child = getChildAt(0); 392 return !(y < child.getTop() 393 || y >= child.getBottom() 394 || x < child.getLeft() - scrollX 395 || x >= child.getRight() - scrollX); 396 } 397 return false; 398 } 399 400 private void initOrResetVelocityTracker() { 401 if (mVelocityTracker == null) { 402 mVelocityTracker = VelocityTracker.obtain(); 403 } else { 404 mVelocityTracker.clear(); 405 } 406 } 407 408 private void initVelocityTrackerIfNotExists() { 409 if (mVelocityTracker == null) { 410 mVelocityTracker = VelocityTracker.obtain(); 411 } 412 } 413 414 private void recycleVelocityTracker() { 415 if (mVelocityTracker != null) { 416 mVelocityTracker.recycle(); 417 mVelocityTracker = null; 418 } 419 } 420 421 @Override 422 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 423 if (disallowIntercept) { 424 recycleVelocityTracker(); 425 } 426 super.requestDisallowInterceptTouchEvent(disallowIntercept); 427 } 428 429 @Override 430 public boolean onInterceptTouchEvent(MotionEvent ev) { 431 /* 432 * This method JUST determines whether we want to intercept the motion. 433 * If we return true, onMotionEvent will be called and we do the actual 434 * scrolling there. 435 */ 436 437 /* 438 * Shortcut the most recurring case: the user is in the dragging 439 * state and he is moving his finger. We want to intercept this 440 * motion. 441 */ 442 final int action = ev.getAction(); 443 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 444 return true; 445 } 446 447 switch (action & MotionEvent.ACTION_MASK) { 448 case MotionEvent.ACTION_MOVE: { 449 /* 450 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 451 * whether the user has moved far enough from his original down touch. 452 */ 453 454 /* 455 * Locally do absolute value. mLastMotionX is set to the x value 456 * of the down event. 457 */ 458 final int activePointerId = mActivePointerId; 459 if (activePointerId == INVALID_POINTER) { 460 // If we don't have a valid id, the touch down wasn't on content. 461 break; 462 } 463 464 final int pointerIndex = ev.findPointerIndex(activePointerId); 465 if (pointerIndex == -1) { 466 Log.e(TAG, "Invalid pointerId=" + activePointerId 467 + " in onInterceptTouchEvent"); 468 break; 469 } 470 471 final int x = (int) ev.getX(pointerIndex); 472 final int xDiff = (int) Math.abs(x - mLastMotionX); 473 if (xDiff > mTouchSlop) { 474 mIsBeingDragged = true; 475 mLastMotionX = x; 476 initVelocityTrackerIfNotExists(); 477 mVelocityTracker.addMovement(ev); 478 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 479 } 480 break; 481 } 482 483 case MotionEvent.ACTION_DOWN: { 484 final int x = (int) ev.getX(); 485 if (!inChild((int) x, (int) ev.getY())) { 486 mIsBeingDragged = false; 487 recycleVelocityTracker(); 488 break; 489 } 490 491 /* 492 * Remember location of down touch. 493 * ACTION_DOWN always refers to pointer index 0. 494 */ 495 mLastMotionX = x; 496 mActivePointerId = ev.getPointerId(0); 497 498 initOrResetVelocityTracker(); 499 mVelocityTracker.addMovement(ev); 500 501 /* 502 * If being flinged and user touches the screen, initiate drag; 503 * otherwise don't. mScroller.isFinished should be false when 504 * being flinged. 505 */ 506 mIsBeingDragged = !mScroller.isFinished(); 507 break; 508 } 509 510 case MotionEvent.ACTION_CANCEL: 511 case MotionEvent.ACTION_UP: 512 /* Release the drag */ 513 mIsBeingDragged = false; 514 mActivePointerId = INVALID_POINTER; 515 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 516 postInvalidateOnAnimation(); 517 } 518 break; 519 case MotionEvent.ACTION_POINTER_DOWN: { 520 final int index = ev.getActionIndex(); 521 mLastMotionX = (int) ev.getX(index); 522 mActivePointerId = ev.getPointerId(index); 523 break; 524 } 525 case MotionEvent.ACTION_POINTER_UP: 526 onSecondaryPointerUp(ev); 527 mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId)); 528 break; 529 } 530 531 /* 532 * The only time we want to intercept motion events is if we are in the 533 * drag mode. 534 */ 535 return mIsBeingDragged; 536 } 537 538 @Override 539 public boolean onTouchEvent(MotionEvent ev) { 540 initVelocityTrackerIfNotExists(); 541 mVelocityTracker.addMovement(ev); 542 543 final int action = ev.getAction(); 544 545 switch (action & MotionEvent.ACTION_MASK) { 546 case MotionEvent.ACTION_DOWN: { 547 if (getChildCount() == 0) { 548 return false; 549 } 550 if ((mIsBeingDragged = !mScroller.isFinished())) { 551 final ViewParent parent = getParent(); 552 if (parent != null) { 553 parent.requestDisallowInterceptTouchEvent(true); 554 } 555 } 556 557 /* 558 * If being flinged and user touches, stop the fling. isFinished 559 * will be false if being flinged. 560 */ 561 if (!mScroller.isFinished()) { 562 mScroller.abortAnimation(); 563 } 564 565 // Remember where the motion event started 566 mLastMotionX = (int) ev.getX(); 567 mActivePointerId = ev.getPointerId(0); 568 break; 569 } 570 case MotionEvent.ACTION_MOVE: 571 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 572 if (activePointerIndex == -1) { 573 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 574 break; 575 } 576 577 final int x = (int) ev.getX(activePointerIndex); 578 int deltaX = mLastMotionX - x; 579 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 580 final ViewParent parent = getParent(); 581 if (parent != null) { 582 parent.requestDisallowInterceptTouchEvent(true); 583 } 584 mIsBeingDragged = true; 585 if (deltaX > 0) { 586 deltaX -= mTouchSlop; 587 } else { 588 deltaX += mTouchSlop; 589 } 590 } 591 if (mIsBeingDragged) { 592 // Scroll to follow the motion event 593 mLastMotionX = x; 594 595 final int oldX = mScrollX; 596 final int oldY = mScrollY; 597 final int range = getScrollRange(); 598 final int overscrollMode = getOverScrollMode(); 599 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 600 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 601 602 // Calling overScrollBy will call onOverScrolled, which 603 // calls onScrollChanged if applicable. 604 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 605 mOverscrollDistance, 0, true)) { 606 // Break our velocity if we hit a scroll barrier. 607 mVelocityTracker.clear(); 608 } 609 610 if (canOverscroll) { 611 final int pulledToX = oldX + deltaX; 612 if (pulledToX < 0) { 613 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 614 if (!mEdgeGlowRight.isFinished()) { 615 mEdgeGlowRight.onRelease(); 616 } 617 } else if (pulledToX > range) { 618 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 619 if (!mEdgeGlowLeft.isFinished()) { 620 mEdgeGlowLeft.onRelease(); 621 } 622 } 623 if (mEdgeGlowLeft != null 624 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 625 postInvalidateOnAnimation(); 626 } 627 } 628 } 629 break; 630 case MotionEvent.ACTION_UP: 631 if (mIsBeingDragged) { 632 final VelocityTracker velocityTracker = mVelocityTracker; 633 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 634 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 635 636 if (getChildCount() > 0) { 637 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 638 fling(-initialVelocity); 639 } else { 640 if (mScroller.springBack(mScrollX, mScrollY, 0, 641 getScrollRange(), 0, 0)) { 642 postInvalidateOnAnimation(); 643 } 644 } 645 } 646 647 mActivePointerId = INVALID_POINTER; 648 mIsBeingDragged = false; 649 recycleVelocityTracker(); 650 651 if (mEdgeGlowLeft != null) { 652 mEdgeGlowLeft.onRelease(); 653 mEdgeGlowRight.onRelease(); 654 } 655 } 656 break; 657 case MotionEvent.ACTION_CANCEL: 658 if (mIsBeingDragged && getChildCount() > 0) { 659 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 660 postInvalidateOnAnimation(); 661 } 662 mActivePointerId = INVALID_POINTER; 663 mIsBeingDragged = false; 664 recycleVelocityTracker(); 665 666 if (mEdgeGlowLeft != null) { 667 mEdgeGlowLeft.onRelease(); 668 mEdgeGlowRight.onRelease(); 669 } 670 } 671 break; 672 case MotionEvent.ACTION_POINTER_UP: 673 onSecondaryPointerUp(ev); 674 break; 675 } 676 return true; 677 } 678 679 private void onSecondaryPointerUp(MotionEvent ev) { 680 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 681 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 682 final int pointerId = ev.getPointerId(pointerIndex); 683 if (pointerId == mActivePointerId) { 684 // This was our active pointer going up. Choose a new 685 // active pointer and adjust accordingly. 686 // TODO: Make this decision more intelligent. 687 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 688 mLastMotionX = (int) ev.getX(newPointerIndex); 689 mActivePointerId = ev.getPointerId(newPointerIndex); 690 if (mVelocityTracker != null) { 691 mVelocityTracker.clear(); 692 } 693 } 694 } 695 696 @Override 697 public boolean onGenericMotionEvent(MotionEvent event) { 698 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 699 switch (event.getAction()) { 700 case MotionEvent.ACTION_SCROLL: { 701 if (!mIsBeingDragged) { 702 final float hscroll; 703 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 704 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 705 } else { 706 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 707 } 708 if (hscroll != 0) { 709 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 710 final int range = getScrollRange(); 711 int oldScrollX = mScrollX; 712 int newScrollX = oldScrollX + delta; 713 if (newScrollX < 0) { 714 newScrollX = 0; 715 } else if (newScrollX > range) { 716 newScrollX = range; 717 } 718 if (newScrollX != oldScrollX) { 719 super.scrollTo(newScrollX, mScrollY); 720 return true; 721 } 722 } 723 } 724 } 725 } 726 } 727 return super.onGenericMotionEvent(event); 728 } 729 730 @Override 731 public boolean shouldDelayChildPressedState() { 732 return true; 733 } 734 735 @Override 736 protected void onOverScrolled(int scrollX, int scrollY, 737 boolean clampedX, boolean clampedY) { 738 // Treat animating scrolls differently; see #computeScroll() for why. 739 if (!mScroller.isFinished()) { 740 final int oldX = mScrollX; 741 final int oldY = mScrollY; 742 mScrollX = scrollX; 743 mScrollY = scrollY; 744 invalidateParentIfNeeded(); 745 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 746 if (clampedX) { 747 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 748 } 749 } else { 750 super.scrollTo(scrollX, scrollY); 751 } 752 753 awakenScrollBars(); 754 } 755 756 @Override 757 public boolean performAccessibilityAction(int action, Bundle arguments) { 758 if (super.performAccessibilityAction(action, arguments)) { 759 return true; 760 } 761 switch (action) { 762 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 763 if (!isEnabled()) { 764 return false; 765 } 766 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 767 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 768 if (targetScrollX != mScrollX) { 769 smoothScrollTo(targetScrollX, 0); 770 return true; 771 } 772 } return false; 773 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 774 if (!isEnabled()) { 775 return false; 776 } 777 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 778 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 779 if (targetScrollX != mScrollX) { 780 smoothScrollTo(targetScrollX, 0); 781 return true; 782 } 783 } return false; 784 } 785 return false; 786 } 787 788 @Override 789 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 790 super.onInitializeAccessibilityNodeInfo(info); 791 info.setClassName(HorizontalScrollView.class.getName()); 792 final int scrollRange = getScrollRange(); 793 if (scrollRange > 0) { 794 info.setScrollable(true); 795 if (isEnabled() && mScrollX > 0) { 796 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 797 } 798 if (isEnabled() && mScrollX < scrollRange) { 799 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 800 } 801 } 802 } 803 804 @Override 805 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 806 super.onInitializeAccessibilityEvent(event); 807 event.setClassName(HorizontalScrollView.class.getName()); 808 event.setScrollable(getScrollRange() > 0); 809 event.setScrollX(mScrollX); 810 event.setScrollY(mScrollY); 811 event.setMaxScrollX(getScrollRange()); 812 event.setMaxScrollY(mScrollY); 813 } 814 815 private int getScrollRange() { 816 int scrollRange = 0; 817 if (getChildCount() > 0) { 818 View child = getChildAt(0); 819 scrollRange = Math.max(0, 820 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 821 } 822 return scrollRange; 823 } 824 825 /** 826 * <p> 827 * Finds the next focusable component that fits in this View's bounds 828 * (excluding fading edges) pretending that this View's left is located at 829 * the parameter left. 830 * </p> 831 * 832 * @param leftFocus look for a candidate is the one at the left of the bounds 833 * if leftFocus is true, or at the right of the bounds if leftFocus 834 * is false 835 * @param left the left offset of the bounds in which a focusable must be 836 * found (the fading edge is assumed to start at this position) 837 * @param preferredFocusable the View that has highest priority and will be 838 * returned if it is within my bounds (null is valid) 839 * @return the next focusable component in the bounds or null if none can be found 840 */ 841 private View findFocusableViewInMyBounds(final boolean leftFocus, 842 final int left, View preferredFocusable) { 843 /* 844 * The fading edge's transparent side should be considered for focus 845 * since it's mostly visible, so we divide the actual fading edge length 846 * by 2. 847 */ 848 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 849 final int leftWithoutFadingEdge = left + fadingEdgeLength; 850 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 851 852 if ((preferredFocusable != null) 853 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 854 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 855 return preferredFocusable; 856 } 857 858 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 859 rightWithoutFadingEdge); 860 } 861 862 /** 863 * <p> 864 * Finds the next focusable component that fits in the specified bounds. 865 * </p> 866 * 867 * @param leftFocus look for a candidate is the one at the left of the bounds 868 * if leftFocus is true, or at the right of the bounds if 869 * leftFocus is false 870 * @param left the left offset of the bounds in which a focusable must be 871 * found 872 * @param right the right offset of the bounds in which a focusable must 873 * be found 874 * @return the next focusable component in the bounds or null if none can 875 * be found 876 */ 877 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 878 879 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 880 View focusCandidate = null; 881 882 /* 883 * A fully contained focusable is one where its left is below the bound's 884 * left, and its right is above the bound's right. A partially 885 * contained focusable is one where some part of it is within the 886 * bounds, but it also has some part that is not within bounds. A fully contained 887 * focusable is preferred to a partially contained focusable. 888 */ 889 boolean foundFullyContainedFocusable = false; 890 891 int count = focusables.size(); 892 for (int i = 0; i < count; i++) { 893 View view = focusables.get(i); 894 int viewLeft = view.getLeft(); 895 int viewRight = view.getRight(); 896 897 if (left < viewRight && viewLeft < right) { 898 /* 899 * the focusable is in the target area, it is a candidate for 900 * focusing 901 */ 902 903 final boolean viewIsFullyContained = (left < viewLeft) && 904 (viewRight < right); 905 906 if (focusCandidate == null) { 907 /* No candidate, take this one */ 908 focusCandidate = view; 909 foundFullyContainedFocusable = viewIsFullyContained; 910 } else { 911 final boolean viewIsCloserToBoundary = 912 (leftFocus && viewLeft < focusCandidate.getLeft()) || 913 (!leftFocus && viewRight > focusCandidate.getRight()); 914 915 if (foundFullyContainedFocusable) { 916 if (viewIsFullyContained && viewIsCloserToBoundary) { 917 /* 918 * We're dealing with only fully contained views, so 919 * it has to be closer to the boundary to beat our 920 * candidate 921 */ 922 focusCandidate = view; 923 } 924 } else { 925 if (viewIsFullyContained) { 926 /* Any fully contained view beats a partially contained view */ 927 focusCandidate = view; 928 foundFullyContainedFocusable = true; 929 } else if (viewIsCloserToBoundary) { 930 /* 931 * Partially contained view beats another partially 932 * contained view if it's closer 933 */ 934 focusCandidate = view; 935 } 936 } 937 } 938 } 939 } 940 941 return focusCandidate; 942 } 943 944 /** 945 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 946 * method will scroll the view by one page left or right and give the focus 947 * to the leftmost/rightmost component in the new visible area. If no 948 * component is a good candidate for focus, this scrollview reclaims the 949 * focus.</p> 950 * 951 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 952 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 953 * to go one page right 954 * @return true if the key event is consumed by this method, false otherwise 955 */ 956 public boolean pageScroll(int direction) { 957 boolean right = direction == View.FOCUS_RIGHT; 958 int width = getWidth(); 959 960 if (right) { 961 mTempRect.left = getScrollX() + width; 962 int count = getChildCount(); 963 if (count > 0) { 964 View view = getChildAt(0); 965 if (mTempRect.left + width > view.getRight()) { 966 mTempRect.left = view.getRight() - width; 967 } 968 } 969 } else { 970 mTempRect.left = getScrollX() - width; 971 if (mTempRect.left < 0) { 972 mTempRect.left = 0; 973 } 974 } 975 mTempRect.right = mTempRect.left + width; 976 977 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 978 } 979 980 /** 981 * <p>Handles scrolling in response to a "home/end" shortcut press. This 982 * method will scroll the view to the left or right and give the focus 983 * to the leftmost/rightmost component in the new visible area. If no 984 * component is a good candidate for focus, this scrollview reclaims the 985 * focus.</p> 986 * 987 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 988 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 989 * to go the right 990 * @return true if the key event is consumed by this method, false otherwise 991 */ 992 public boolean fullScroll(int direction) { 993 boolean right = direction == View.FOCUS_RIGHT; 994 int width = getWidth(); 995 996 mTempRect.left = 0; 997 mTempRect.right = width; 998 999 if (right) { 1000 int count = getChildCount(); 1001 if (count > 0) { 1002 View view = getChildAt(0); 1003 mTempRect.right = view.getRight(); 1004 mTempRect.left = mTempRect.right - width; 1005 } 1006 } 1007 1008 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 1009 } 1010 1011 /** 1012 * <p>Scrolls the view to make the area defined by <code>left</code> and 1013 * <code>right</code> visible. This method attempts to give the focus 1014 * to a component visible in this area. If no component can be focused in 1015 * the new visible area, the focus is reclaimed by this scrollview.</p> 1016 * 1017 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1018 * to go left {@link android.view.View#FOCUS_RIGHT} to right 1019 * @param left the left offset of the new area to be made visible 1020 * @param right the right offset of the new area to be made visible 1021 * @return true if the key event is consumed by this method, false otherwise 1022 */ 1023 private boolean scrollAndFocus(int direction, int left, int right) { 1024 boolean handled = true; 1025 1026 int width = getWidth(); 1027 int containerLeft = getScrollX(); 1028 int containerRight = containerLeft + width; 1029 boolean goLeft = direction == View.FOCUS_LEFT; 1030 1031 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1032 if (newFocused == null) { 1033 newFocused = this; 1034 } 1035 1036 if (left >= containerLeft && right <= containerRight) { 1037 handled = false; 1038 } else { 1039 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1040 doScrollX(delta); 1041 } 1042 1043 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1044 1045 return handled; 1046 } 1047 1048 /** 1049 * Handle scrolling in response to a left or right arrow click. 1050 * 1051 * @param direction The direction corresponding to the arrow key that was 1052 * pressed 1053 * @return True if we consumed the event, false otherwise 1054 */ 1055 public boolean arrowScroll(int direction) { 1056 1057 View currentFocused = findFocus(); 1058 if (currentFocused == this) currentFocused = null; 1059 1060 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1061 1062 final int maxJump = getMaxScrollAmount(); 1063 1064 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1065 nextFocused.getDrawingRect(mTempRect); 1066 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1067 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1068 doScrollX(scrollDelta); 1069 nextFocused.requestFocus(direction); 1070 } else { 1071 // no new focus 1072 int scrollDelta = maxJump; 1073 1074 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1075 scrollDelta = getScrollX(); 1076 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1077 1078 int daRight = getChildAt(0).getRight(); 1079 1080 int screenRight = getScrollX() + getWidth(); 1081 1082 if (daRight - screenRight < maxJump) { 1083 scrollDelta = daRight - screenRight; 1084 } 1085 } 1086 if (scrollDelta == 0) { 1087 return false; 1088 } 1089 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1090 } 1091 1092 if (currentFocused != null && currentFocused.isFocused() 1093 && isOffScreen(currentFocused)) { 1094 // previously focused item still has focus and is off screen, give 1095 // it up (take it back to ourselves) 1096 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1097 // sure to 1098 // get it) 1099 final int descendantFocusability = getDescendantFocusability(); // save 1100 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1101 requestFocus(); 1102 setDescendantFocusability(descendantFocusability); // restore 1103 } 1104 return true; 1105 } 1106 1107 /** 1108 * @return whether the descendant of this scroll view is scrolled off 1109 * screen. 1110 */ 1111 private boolean isOffScreen(View descendant) { 1112 return !isWithinDeltaOfScreen(descendant, 0); 1113 } 1114 1115 /** 1116 * @return whether the descendant of this scroll view is within delta 1117 * pixels of being on the screen. 1118 */ 1119 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1120 descendant.getDrawingRect(mTempRect); 1121 offsetDescendantRectToMyCoords(descendant, mTempRect); 1122 1123 return (mTempRect.right + delta) >= getScrollX() 1124 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1125 } 1126 1127 /** 1128 * Smooth scroll by a X delta 1129 * 1130 * @param delta the number of pixels to scroll by on the X axis 1131 */ 1132 private void doScrollX(int delta) { 1133 if (delta != 0) { 1134 if (mSmoothScrollingEnabled) { 1135 smoothScrollBy(delta, 0); 1136 } else { 1137 scrollBy(delta, 0); 1138 } 1139 } 1140 } 1141 1142 /** 1143 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1144 * 1145 * @param dx the number of pixels to scroll by on the X axis 1146 * @param dy the number of pixels to scroll by on the Y axis 1147 */ 1148 public final void smoothScrollBy(int dx, int dy) { 1149 if (getChildCount() == 0) { 1150 // Nothing to do. 1151 return; 1152 } 1153 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1154 if (duration > ANIMATED_SCROLL_GAP) { 1155 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1156 final int right = getChildAt(0).getWidth(); 1157 final int maxX = Math.max(0, right - width); 1158 final int scrollX = mScrollX; 1159 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1160 1161 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1162 postInvalidateOnAnimation(); 1163 } else { 1164 if (!mScroller.isFinished()) { 1165 mScroller.abortAnimation(); 1166 } 1167 scrollBy(dx, dy); 1168 } 1169 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1170 } 1171 1172 /** 1173 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1174 * 1175 * @param x the position where to scroll on the X axis 1176 * @param y the position where to scroll on the Y axis 1177 */ 1178 public final void smoothScrollTo(int x, int y) { 1179 smoothScrollBy(x - mScrollX, y - mScrollY); 1180 } 1181 1182 /** 1183 * <p>The scroll range of a scroll view is the overall width of all of its 1184 * children.</p> 1185 */ 1186 @Override 1187 protected int computeHorizontalScrollRange() { 1188 final int count = getChildCount(); 1189 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1190 if (count == 0) { 1191 return contentWidth; 1192 } 1193 1194 int scrollRange = getChildAt(0).getRight(); 1195 final int scrollX = mScrollX; 1196 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1197 if (scrollX < 0) { 1198 scrollRange -= scrollX; 1199 } else if (scrollX > overscrollRight) { 1200 scrollRange += scrollX - overscrollRight; 1201 } 1202 1203 return scrollRange; 1204 } 1205 1206 @Override 1207 protected int computeHorizontalScrollOffset() { 1208 return Math.max(0, super.computeHorizontalScrollOffset()); 1209 } 1210 1211 @Override 1212 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1213 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1214 1215 int childWidthMeasureSpec; 1216 int childHeightMeasureSpec; 1217 1218 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1219 + mPaddingBottom, lp.height); 1220 1221 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1222 1223 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1224 } 1225 1226 @Override 1227 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1228 int parentHeightMeasureSpec, int heightUsed) { 1229 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1230 1231 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1232 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1233 + heightUsed, lp.height); 1234 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1235 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1236 1237 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1238 } 1239 1240 @Override 1241 public void computeScroll() { 1242 if (mScroller.computeScrollOffset()) { 1243 // This is called at drawing time by ViewGroup. We don't want to 1244 // re-show the scrollbars at this point, which scrollTo will do, 1245 // so we replicate most of scrollTo here. 1246 // 1247 // It's a little odd to call onScrollChanged from inside the drawing. 1248 // 1249 // It is, except when you remember that computeScroll() is used to 1250 // animate scrolling. So unless we want to defer the onScrollChanged() 1251 // until the end of the animated scrolling, we don't really have a 1252 // choice here. 1253 // 1254 // I agree. The alternative, which I think would be worse, is to post 1255 // something and tell the subclasses later. This is bad because there 1256 // will be a window where mScrollX/Y is different from what the app 1257 // thinks it is. 1258 // 1259 int oldX = mScrollX; 1260 int oldY = mScrollY; 1261 int x = mScroller.getCurrX(); 1262 int y = mScroller.getCurrY(); 1263 1264 if (oldX != x || oldY != y) { 1265 final int range = getScrollRange(); 1266 final int overscrollMode = getOverScrollMode(); 1267 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1268 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1269 1270 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1271 mOverflingDistance, 0, false); 1272 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1273 1274 if (canOverscroll) { 1275 if (x < 0 && oldX >= 0) { 1276 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1277 } else if (x > range && oldX <= range) { 1278 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1279 } 1280 } 1281 } 1282 1283 if (!awakenScrollBars()) { 1284 postInvalidateOnAnimation(); 1285 } 1286 } 1287 } 1288 1289 /** 1290 * Scrolls the view to the given child. 1291 * 1292 * @param child the View to scroll to 1293 */ 1294 private void scrollToChild(View child) { 1295 child.getDrawingRect(mTempRect); 1296 1297 /* Offset from child's local coordinates to ScrollView coordinates */ 1298 offsetDescendantRectToMyCoords(child, mTempRect); 1299 1300 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1301 1302 if (scrollDelta != 0) { 1303 scrollBy(scrollDelta, 0); 1304 } 1305 } 1306 1307 /** 1308 * If rect is off screen, scroll just enough to get it (or at least the 1309 * first screen size chunk of it) on screen. 1310 * 1311 * @param rect The rectangle. 1312 * @param immediate True to scroll immediately without animation 1313 * @return true if scrolling was performed 1314 */ 1315 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1316 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1317 final boolean scroll = delta != 0; 1318 if (scroll) { 1319 if (immediate) { 1320 scrollBy(delta, 0); 1321 } else { 1322 smoothScrollBy(delta, 0); 1323 } 1324 } 1325 return scroll; 1326 } 1327 1328 /** 1329 * Compute the amount to scroll in the X direction in order to get 1330 * a rectangle completely on the screen (or, if taller than the screen, 1331 * at least the first screen size chunk of it). 1332 * 1333 * @param rect The rect. 1334 * @return The scroll delta. 1335 */ 1336 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1337 if (getChildCount() == 0) return 0; 1338 1339 int width = getWidth(); 1340 int screenLeft = getScrollX(); 1341 int screenRight = screenLeft + width; 1342 1343 int fadingEdge = getHorizontalFadingEdgeLength(); 1344 1345 // leave room for left fading edge as long as rect isn't at very left 1346 if (rect.left > 0) { 1347 screenLeft += fadingEdge; 1348 } 1349 1350 // leave room for right fading edge as long as rect isn't at very right 1351 if (rect.right < getChildAt(0).getWidth()) { 1352 screenRight -= fadingEdge; 1353 } 1354 1355 int scrollXDelta = 0; 1356 1357 if (rect.right > screenRight && rect.left > screenLeft) { 1358 // need to move right to get it in view: move right just enough so 1359 // that the entire rectangle is in view (or at least the first 1360 // screen size chunk). 1361 1362 if (rect.width() > width) { 1363 // just enough to get screen size chunk on 1364 scrollXDelta += (rect.left - screenLeft); 1365 } else { 1366 // get entire rect at right of screen 1367 scrollXDelta += (rect.right - screenRight); 1368 } 1369 1370 // make sure we aren't scrolling beyond the end of our content 1371 int right = getChildAt(0).getRight(); 1372 int distanceToRight = right - screenRight; 1373 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1374 1375 } else if (rect.left < screenLeft && rect.right < screenRight) { 1376 // need to move right to get it in view: move right just enough so that 1377 // entire rectangle is in view (or at least the first screen 1378 // size chunk of it). 1379 1380 if (rect.width() > width) { 1381 // screen size chunk 1382 scrollXDelta -= (screenRight - rect.right); 1383 } else { 1384 // entire rect at left 1385 scrollXDelta -= (screenLeft - rect.left); 1386 } 1387 1388 // make sure we aren't scrolling any further than the left our content 1389 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1390 } 1391 return scrollXDelta; 1392 } 1393 1394 @Override 1395 public void requestChildFocus(View child, View focused) { 1396 if (!mIsLayoutDirty) { 1397 scrollToChild(focused); 1398 } else { 1399 // The child may not be laid out yet, we can't compute the scroll yet 1400 mChildToScrollTo = focused; 1401 } 1402 super.requestChildFocus(child, focused); 1403 } 1404 1405 1406 /** 1407 * When looking for focus in children of a scroll view, need to be a little 1408 * more careful not to give focus to something that is scrolled off screen. 1409 * 1410 * This is more expensive than the default {@link android.view.ViewGroup} 1411 * implementation, otherwise this behavior might have been made the default. 1412 */ 1413 @Override 1414 protected boolean onRequestFocusInDescendants(int direction, 1415 Rect previouslyFocusedRect) { 1416 1417 // convert from forward / backward notation to up / down / left / right 1418 // (ugh). 1419 if (direction == View.FOCUS_FORWARD) { 1420 direction = View.FOCUS_RIGHT; 1421 } else if (direction == View.FOCUS_BACKWARD) { 1422 direction = View.FOCUS_LEFT; 1423 } 1424 1425 final View nextFocus = previouslyFocusedRect == null ? 1426 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1427 FocusFinder.getInstance().findNextFocusFromRect(this, 1428 previouslyFocusedRect, direction); 1429 1430 if (nextFocus == null) { 1431 return false; 1432 } 1433 1434 if (isOffScreen(nextFocus)) { 1435 return false; 1436 } 1437 1438 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1439 } 1440 1441 @Override 1442 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1443 boolean immediate) { 1444 // offset into coordinate space of this scroll view 1445 rectangle.offset(child.getLeft() - child.getScrollX(), 1446 child.getTop() - child.getScrollY()); 1447 1448 return scrollToChildRect(rectangle, immediate); 1449 } 1450 1451 @Override 1452 public void requestLayout() { 1453 mIsLayoutDirty = true; 1454 super.requestLayout(); 1455 } 1456 1457 @Override 1458 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1459 int childWidth = 0; 1460 int childMargins = 0; 1461 1462 if (getChildCount() > 0) { 1463 childWidth = getChildAt(0).getMeasuredWidth(); 1464 LayoutParams childParams = (LayoutParams) getChildAt(0).getLayoutParams(); 1465 childMargins = childParams.leftMargin + childParams.rightMargin; 1466 } 1467 1468 final int available = r - l - getPaddingLeftWithForeground() - 1469 getPaddingRightWithForeground() - childMargins; 1470 1471 final boolean forceLeftGravity = (childWidth > available); 1472 1473 layoutChildren(l, t, r, b, forceLeftGravity); 1474 1475 mIsLayoutDirty = false; 1476 // Give a child focus if it needs it 1477 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1478 scrollToChild(mChildToScrollTo); 1479 } 1480 mChildToScrollTo = null; 1481 1482 if (!hasLayout()) { 1483 final int scrollRange = Math.max(0, 1484 childWidth - (r - l - mPaddingLeft - mPaddingRight)); 1485 if (mSavedState != null) { 1486 if (isLayoutRtl() == mSavedState.isLayoutRtl) { 1487 mScrollX = mSavedState.scrollPosition; 1488 } else { 1489 mScrollX = scrollRange - mSavedState.scrollPosition; 1490 } 1491 mSavedState = null; 1492 } else { 1493 if (isLayoutRtl()) { 1494 mScrollX = scrollRange - mScrollX; 1495 } // mScrollX default value is "0" for LTR 1496 } 1497 // Don't forget to clamp 1498 if (mScrollX > scrollRange) { 1499 mScrollX = scrollRange; 1500 } else if (mScrollX < 0) { 1501 mScrollX = 0; 1502 } 1503 } 1504 1505 // Calling this with the present values causes it to re-claim them 1506 scrollTo(mScrollX, mScrollY); 1507 } 1508 1509 @Override 1510 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1511 super.onSizeChanged(w, h, oldw, oldh); 1512 1513 View currentFocused = findFocus(); 1514 if (null == currentFocused || this == currentFocused) 1515 return; 1516 1517 final int maxJump = mRight - mLeft; 1518 1519 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1520 currentFocused.getDrawingRect(mTempRect); 1521 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1522 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1523 doScrollX(scrollDelta); 1524 } 1525 } 1526 1527 /** 1528 * Return true if child is a descendant of parent, (or equal to the parent). 1529 */ 1530 private static boolean isViewDescendantOf(View child, View parent) { 1531 if (child == parent) { 1532 return true; 1533 } 1534 1535 final ViewParent theParent = child.getParent(); 1536 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1537 } 1538 1539 /** 1540 * Fling the scroll view 1541 * 1542 * @param velocityX The initial velocity in the X direction. Positive 1543 * numbers mean that the finger/cursor is moving down the screen, 1544 * which means we want to scroll towards the left. 1545 */ 1546 public void fling(int velocityX) { 1547 if (getChildCount() > 0) { 1548 int width = getWidth() - mPaddingRight - mPaddingLeft; 1549 int right = getChildAt(0).getWidth(); 1550 1551 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1552 Math.max(0, right - width), 0, 0, width/2, 0); 1553 1554 final boolean movingRight = velocityX > 0; 1555 1556 View currentFocused = findFocus(); 1557 View newFocused = findFocusableViewInMyBounds(movingRight, 1558 mScroller.getFinalX(), currentFocused); 1559 1560 if (newFocused == null) { 1561 newFocused = this; 1562 } 1563 1564 if (newFocused != currentFocused) { 1565 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1566 } 1567 1568 postInvalidateOnAnimation(); 1569 } 1570 } 1571 1572 /** 1573 * {@inheritDoc} 1574 * 1575 * <p>This version also clamps the scrolling to the bounds of our child. 1576 */ 1577 @Override 1578 public void scrollTo(int x, int y) { 1579 // we rely on the fact the View.scrollBy calls scrollTo. 1580 if (getChildCount() > 0) { 1581 View child = getChildAt(0); 1582 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1583 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1584 if (x != mScrollX || y != mScrollY) { 1585 super.scrollTo(x, y); 1586 } 1587 } 1588 } 1589 1590 @Override 1591 public void setOverScrollMode(int mode) { 1592 if (mode != OVER_SCROLL_NEVER) { 1593 if (mEdgeGlowLeft == null) { 1594 Context context = getContext(); 1595 mEdgeGlowLeft = new EdgeEffect(context); 1596 mEdgeGlowRight = new EdgeEffect(context); 1597 } 1598 } else { 1599 mEdgeGlowLeft = null; 1600 mEdgeGlowRight = null; 1601 } 1602 super.setOverScrollMode(mode); 1603 } 1604 1605 @SuppressWarnings({"SuspiciousNameCombination"}) 1606 @Override 1607 public void draw(Canvas canvas) { 1608 super.draw(canvas); 1609 if (mEdgeGlowLeft != null) { 1610 final int scrollX = mScrollX; 1611 if (!mEdgeGlowLeft.isFinished()) { 1612 final int restoreCount = canvas.save(); 1613 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1614 1615 canvas.rotate(270); 1616 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1617 mEdgeGlowLeft.setSize(height, getWidth()); 1618 if (mEdgeGlowLeft.draw(canvas)) { 1619 postInvalidateOnAnimation(); 1620 } 1621 canvas.restoreToCount(restoreCount); 1622 } 1623 if (!mEdgeGlowRight.isFinished()) { 1624 final int restoreCount = canvas.save(); 1625 final int width = getWidth(); 1626 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1627 1628 canvas.rotate(90); 1629 canvas.translate(-mPaddingTop, 1630 -(Math.max(getScrollRange(), scrollX) + width)); 1631 mEdgeGlowRight.setSize(height, width); 1632 if (mEdgeGlowRight.draw(canvas)) { 1633 postInvalidateOnAnimation(); 1634 } 1635 canvas.restoreToCount(restoreCount); 1636 } 1637 } 1638 } 1639 1640 private static int clamp(int n, int my, int child) { 1641 if (my >= child || n < 0) { 1642 return 0; 1643 } 1644 if ((my + n) > child) { 1645 return child - my; 1646 } 1647 return n; 1648 } 1649 1650 @Override 1651 protected void onRestoreInstanceState(Parcelable state) { 1652 SavedState ss = (SavedState) state; 1653 super.onRestoreInstanceState(ss.getSuperState()); 1654 mSavedState = ss; 1655 requestLayout(); 1656 } 1657 1658 @Override 1659 protected Parcelable onSaveInstanceState() { 1660 Parcelable superState = super.onSaveInstanceState(); 1661 SavedState ss = new SavedState(superState); 1662 ss.scrollPosition = mScrollX; 1663 ss.isLayoutRtl = isLayoutRtl(); 1664 return ss; 1665 } 1666 1667 static class SavedState extends BaseSavedState { 1668 public int scrollPosition; 1669 public boolean isLayoutRtl; 1670 1671 SavedState(Parcelable superState) { 1672 super(superState); 1673 } 1674 1675 public SavedState(Parcel source) { 1676 super(source); 1677 scrollPosition = source.readInt(); 1678 isLayoutRtl = (source.readInt() == 0) ? true : false; 1679 } 1680 1681 @Override 1682 public void writeToParcel(Parcel dest, int flags) { 1683 super.writeToParcel(dest, flags); 1684 dest.writeInt(scrollPosition); 1685 dest.writeInt(isLayoutRtl ? 1 : 0); 1686 } 1687 1688 @Override 1689 public String toString() { 1690 return "HorizontalScrollView.SavedState{" 1691 + Integer.toHexString(System.identityHashCode(this)) 1692 + " scrollPosition=" + scrollPosition 1693 + " isLayoutRtl=" + isLayoutRtl + "}"; 1694 } 1695 1696 public static final Parcelable.Creator<SavedState> CREATOR 1697 = new Parcelable.Creator<SavedState>() { 1698 public SavedState createFromParcel(Parcel in) { 1699 return new SavedState(in); 1700 } 1701 1702 public SavedState[] newArray(int size) { 1703 return new SavedState[size]; 1704 } 1705 }; 1706 } 1707} 1708