HorizontalScrollView.java revision 4c05c4c216505dde1d9f088cfdb36d2512bcb4fd
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.graphics.RectF; 24import android.os.Build; 25import android.os.Bundle; 26import android.os.Parcel; 27import android.os.Parcelable; 28import android.util.AttributeSet; 29import android.util.Log; 30import android.view.FocusFinder; 31import android.view.InputDevice; 32import android.view.KeyEvent; 33import android.view.MotionEvent; 34import android.view.VelocityTracker; 35import android.view.View; 36import android.view.ViewConfiguration; 37import android.view.ViewDebug; 38import android.view.ViewGroup; 39import android.view.ViewParent; 40import android.view.accessibility.AccessibilityEvent; 41import android.view.accessibility.AccessibilityNodeInfo; 42import android.view.animation.AnimationUtils; 43 44import java.util.List; 45 46/** 47 * Layout container for a view hierarchy that can be scrolled by the user, 48 * allowing it to be larger than the physical display. A HorizontalScrollView 49 * is a {@link FrameLayout}, meaning you should place one child in it 50 * containing the entire contents to scroll; this child may itself be a layout 51 * manager with a complex hierarchy of objects. A child that is often used 52 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 53 * array of top-level items that the user can scroll through. 54 * 55 * <p>The {@link TextView} class also 56 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 57 * using the two together is possible to achieve the effect of a text view 58 * within a larger container. 59 * 60 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 61 * use either {@link ScrollView} or {@link ListView}. 62 * 63 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 64 */ 65public class HorizontalScrollView extends FrameLayout { 66 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 67 68 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 69 70 private static final String TAG = "HorizontalScrollView"; 71 72 private long mLastScroll; 73 74 private final Rect mTempRect = new Rect(); 75 private OverScroller mScroller; 76 private EdgeEffect mEdgeGlowLeft; 77 private EdgeEffect mEdgeGlowRight; 78 79 /** 80 * Position of the last motion event. 81 */ 82 private int mLastMotionX; 83 84 /** 85 * True when the layout has changed but the traversal has not come through yet. 86 * Ideally the view hierarchy would keep track of this for us. 87 */ 88 private boolean mIsLayoutDirty = true; 89 90 /** 91 * The child to give focus to in the event that a child has requested focus while the 92 * layout is dirty. This prevents the scroll from being wrong if the child has not been 93 * laid out before requesting focus. 94 */ 95 private View mChildToScrollTo = null; 96 97 /** 98 * True if the user is currently dragging this ScrollView around. This is 99 * not the same as 'is being flinged', which can be checked by 100 * mScroller.isFinished() (flinging begins when the user lifts his finger). 101 */ 102 private boolean mIsBeingDragged = false; 103 104 /** 105 * Determines speed during touch scrolling 106 */ 107 private VelocityTracker mVelocityTracker; 108 109 /** 110 * When set to true, the scroll view measure its child to make it fill the currently 111 * visible area. 112 */ 113 @ViewDebug.ExportedProperty(category = "layout") 114 private boolean mFillViewport; 115 116 /** 117 * Whether arrow scrolling is animated. 118 */ 119 private boolean mSmoothScrollingEnabled = true; 120 121 private int mTouchSlop; 122 private int mMinimumVelocity; 123 private int mMaximumVelocity; 124 125 private int mOverscrollDistance; 126 private int mOverflingDistance; 127 128 /** 129 * ID of the active pointer. This is used to retain consistency during 130 * drags/flings if multiple pointers are used. 131 */ 132 private int mActivePointerId = INVALID_POINTER; 133 134 /** 135 * Sentinel value for no current active pointer. 136 * Used by {@link #mActivePointerId}. 137 */ 138 private static final int INVALID_POINTER = -1; 139 140 private SavedState mSavedState; 141 142 public HorizontalScrollView(Context context) { 143 this(context, null); 144 } 145 146 public HorizontalScrollView(Context context, AttributeSet attrs) { 147 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 148 } 149 150 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyleAttr) { 151 this(context, attrs, defStyleAttr, 0); 152 } 153 154 public HorizontalScrollView( 155 Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { 156 super(context, attrs, defStyleAttr, defStyleRes); 157 initScrollView(); 158 159 final TypedArray a = context.obtainStyledAttributes( 160 attrs, android.R.styleable.HorizontalScrollView, defStyleAttr, defStyleRes); 161 162 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 163 164 a.recycle(); 165 } 166 167 @Override 168 protected float getLeftFadingEdgeStrength() { 169 if (getChildCount() == 0) { 170 return 0.0f; 171 } 172 173 final int length = getHorizontalFadingEdgeLength(); 174 if (mScrollX < length) { 175 return mScrollX / (float) length; 176 } 177 178 return 1.0f; 179 } 180 181 @Override 182 protected float getRightFadingEdgeStrength() { 183 if (getChildCount() == 0) { 184 return 0.0f; 185 } 186 187 final int length = getHorizontalFadingEdgeLength(); 188 final int rightEdge = getWidth() - mPaddingRight; 189 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 190 if (span < length) { 191 return span / (float) length; 192 } 193 194 return 1.0f; 195 } 196 197 /** 198 * @return The maximum amount this scroll view will scroll in response to 199 * an arrow event. 200 */ 201 public int getMaxScrollAmount() { 202 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 203 } 204 205 206 private void initScrollView() { 207 mScroller = new OverScroller(getContext()); 208 setFocusable(true); 209 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 210 setWillNotDraw(false); 211 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 212 mTouchSlop = configuration.getScaledTouchSlop(); 213 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 214 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 215 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 216 mOverflingDistance = configuration.getScaledOverflingDistance(); 217 } 218 219 @Override 220 public void addView(View child) { 221 if (getChildCount() > 0) { 222 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 223 } 224 225 super.addView(child); 226 } 227 228 @Override 229 public void addView(View child, int index) { 230 if (getChildCount() > 0) { 231 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 232 } 233 234 super.addView(child, index); 235 } 236 237 @Override 238 public void addView(View child, ViewGroup.LayoutParams params) { 239 if (getChildCount() > 0) { 240 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 241 } 242 243 super.addView(child, params); 244 } 245 246 @Override 247 public void addView(View child, int index, ViewGroup.LayoutParams params) { 248 if (getChildCount() > 0) { 249 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 250 } 251 252 super.addView(child, index, params); 253 } 254 255 /** 256 * @return Returns true this HorizontalScrollView can be scrolled 257 */ 258 private boolean canScroll() { 259 View child = getChildAt(0); 260 if (child != null) { 261 int childWidth = child.getWidth(); 262 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 263 } 264 return false; 265 } 266 267 /** 268 * Indicates whether this HorizontalScrollView's content is stretched to 269 * fill the viewport. 270 * 271 * @return True if the content fills the viewport, false otherwise. 272 * 273 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 274 */ 275 public boolean isFillViewport() { 276 return mFillViewport; 277 } 278 279 /** 280 * Indicates this HorizontalScrollView whether it should stretch its content width 281 * to fill the viewport or not. 282 * 283 * @param fillViewport True to stretch the content's width to the viewport's 284 * boundaries, false otherwise. 285 * 286 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 287 */ 288 public void setFillViewport(boolean fillViewport) { 289 if (fillViewport != mFillViewport) { 290 mFillViewport = fillViewport; 291 requestLayout(); 292 } 293 } 294 295 /** 296 * @return Whether arrow scrolling will animate its transition. 297 */ 298 public boolean isSmoothScrollingEnabled() { 299 return mSmoothScrollingEnabled; 300 } 301 302 /** 303 * Set whether arrow scrolling will animate its transition. 304 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 305 */ 306 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 307 mSmoothScrollingEnabled = smoothScrollingEnabled; 308 } 309 310 @Override 311 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 312 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 313 314 if (!mFillViewport) { 315 return; 316 } 317 318 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 319 if (widthMode == MeasureSpec.UNSPECIFIED) { 320 return; 321 } 322 323 if (getChildCount() > 0) { 324 final View child = getChildAt(0); 325 int width = getMeasuredWidth(); 326 if (child.getMeasuredWidth() < width) { 327 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 328 329 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 330 + mPaddingBottom, lp.height); 331 width -= mPaddingLeft; 332 width -= mPaddingRight; 333 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 334 335 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 336 } 337 } 338 } 339 340 @Override 341 public boolean dispatchKeyEvent(KeyEvent event) { 342 // Let the focused view and/or our descendants get the key first 343 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 344 } 345 346 /** 347 * You can call this function yourself to have the scroll view perform 348 * scrolling from a key event, just as if the event had been dispatched to 349 * it by the view hierarchy. 350 * 351 * @param event The key event to execute. 352 * @return Return true if the event was handled, else false. 353 */ 354 public boolean executeKeyEvent(KeyEvent event) { 355 mTempRect.setEmpty(); 356 357 if (!canScroll()) { 358 if (isFocused()) { 359 View currentFocused = findFocus(); 360 if (currentFocused == this) currentFocused = null; 361 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 362 currentFocused, View.FOCUS_RIGHT); 363 return nextFocused != null && nextFocused != this && 364 nextFocused.requestFocus(View.FOCUS_RIGHT); 365 } 366 return false; 367 } 368 369 boolean handled = false; 370 if (event.getAction() == KeyEvent.ACTION_DOWN) { 371 switch (event.getKeyCode()) { 372 case KeyEvent.KEYCODE_DPAD_LEFT: 373 if (!event.isAltPressed()) { 374 handled = arrowScroll(View.FOCUS_LEFT); 375 } else { 376 handled = fullScroll(View.FOCUS_LEFT); 377 } 378 break; 379 case KeyEvent.KEYCODE_DPAD_RIGHT: 380 if (!event.isAltPressed()) { 381 handled = arrowScroll(View.FOCUS_RIGHT); 382 } else { 383 handled = fullScroll(View.FOCUS_RIGHT); 384 } 385 break; 386 case KeyEvent.KEYCODE_SPACE: 387 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 388 break; 389 } 390 } 391 392 return handled; 393 } 394 395 private boolean inChild(int x, int y) { 396 if (getChildCount() > 0) { 397 final int scrollX = mScrollX; 398 final View child = getChildAt(0); 399 return !(y < child.getTop() 400 || y >= child.getBottom() 401 || x < child.getLeft() - scrollX 402 || x >= child.getRight() - scrollX); 403 } 404 return false; 405 } 406 407 private void initOrResetVelocityTracker() { 408 if (mVelocityTracker == null) { 409 mVelocityTracker = VelocityTracker.obtain(); 410 } else { 411 mVelocityTracker.clear(); 412 } 413 } 414 415 private void initVelocityTrackerIfNotExists() { 416 if (mVelocityTracker == null) { 417 mVelocityTracker = VelocityTracker.obtain(); 418 } 419 } 420 421 private void recycleVelocityTracker() { 422 if (mVelocityTracker != null) { 423 mVelocityTracker.recycle(); 424 mVelocityTracker = null; 425 } 426 } 427 428 @Override 429 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 430 if (disallowIntercept) { 431 recycleVelocityTracker(); 432 } 433 super.requestDisallowInterceptTouchEvent(disallowIntercept); 434 } 435 436 @Override 437 public boolean onInterceptTouchEvent(MotionEvent ev) { 438 /* 439 * This method JUST determines whether we want to intercept the motion. 440 * If we return true, onMotionEvent will be called and we do the actual 441 * scrolling there. 442 */ 443 444 /* 445 * Shortcut the most recurring case: the user is in the dragging 446 * state and he is moving his finger. We want to intercept this 447 * motion. 448 */ 449 final int action = ev.getAction(); 450 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 451 return true; 452 } 453 454 switch (action & MotionEvent.ACTION_MASK) { 455 case MotionEvent.ACTION_MOVE: { 456 /* 457 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 458 * whether the user has moved far enough from his original down touch. 459 */ 460 461 /* 462 * Locally do absolute value. mLastMotionX is set to the x value 463 * of the down event. 464 */ 465 final int activePointerId = mActivePointerId; 466 if (activePointerId == INVALID_POINTER) { 467 // If we don't have a valid id, the touch down wasn't on content. 468 break; 469 } 470 471 final int pointerIndex = ev.findPointerIndex(activePointerId); 472 if (pointerIndex == -1) { 473 Log.e(TAG, "Invalid pointerId=" + activePointerId 474 + " in onInterceptTouchEvent"); 475 break; 476 } 477 478 final int x = (int) ev.getX(pointerIndex); 479 final int xDiff = (int) Math.abs(x - mLastMotionX); 480 if (xDiff > mTouchSlop) { 481 mIsBeingDragged = true; 482 mLastMotionX = x; 483 initVelocityTrackerIfNotExists(); 484 mVelocityTracker.addMovement(ev); 485 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 486 } 487 break; 488 } 489 490 case MotionEvent.ACTION_DOWN: { 491 final int x = (int) ev.getX(); 492 if (!inChild((int) x, (int) ev.getY())) { 493 mIsBeingDragged = false; 494 recycleVelocityTracker(); 495 break; 496 } 497 498 /* 499 * Remember location of down touch. 500 * ACTION_DOWN always refers to pointer index 0. 501 */ 502 mLastMotionX = x; 503 mActivePointerId = ev.getPointerId(0); 504 505 initOrResetVelocityTracker(); 506 mVelocityTracker.addMovement(ev); 507 508 /* 509 * If being flinged and user touches the screen, initiate drag; 510 * otherwise don't. mScroller.isFinished should be false when 511 * being flinged. 512 */ 513 mIsBeingDragged = !mScroller.isFinished(); 514 break; 515 } 516 517 case MotionEvent.ACTION_CANCEL: 518 case MotionEvent.ACTION_UP: 519 /* Release the drag */ 520 mIsBeingDragged = false; 521 mActivePointerId = INVALID_POINTER; 522 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 523 postInvalidateOnAnimation(); 524 } 525 break; 526 case MotionEvent.ACTION_POINTER_DOWN: { 527 final int index = ev.getActionIndex(); 528 mLastMotionX = (int) ev.getX(index); 529 mActivePointerId = ev.getPointerId(index); 530 break; 531 } 532 case MotionEvent.ACTION_POINTER_UP: 533 onSecondaryPointerUp(ev); 534 mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId)); 535 break; 536 } 537 538 /* 539 * The only time we want to intercept motion events is if we are in the 540 * drag mode. 541 */ 542 return mIsBeingDragged; 543 } 544 545 @Override 546 public boolean onTouchEvent(MotionEvent ev) { 547 initVelocityTrackerIfNotExists(); 548 mVelocityTracker.addMovement(ev); 549 550 final int action = ev.getAction(); 551 552 switch (action & MotionEvent.ACTION_MASK) { 553 case MotionEvent.ACTION_DOWN: { 554 if (getChildCount() == 0) { 555 return false; 556 } 557 if ((mIsBeingDragged = !mScroller.isFinished())) { 558 final ViewParent parent = getParent(); 559 if (parent != null) { 560 parent.requestDisallowInterceptTouchEvent(true); 561 } 562 } 563 564 /* 565 * If being flinged and user touches, stop the fling. isFinished 566 * will be false if being flinged. 567 */ 568 if (!mScroller.isFinished()) { 569 mScroller.abortAnimation(); 570 } 571 572 // Remember where the motion event started 573 mLastMotionX = (int) ev.getX(); 574 mActivePointerId = ev.getPointerId(0); 575 break; 576 } 577 case MotionEvent.ACTION_MOVE: 578 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 579 if (activePointerIndex == -1) { 580 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 581 break; 582 } 583 584 final int x = (int) ev.getX(activePointerIndex); 585 int deltaX = mLastMotionX - x; 586 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 587 final ViewParent parent = getParent(); 588 if (parent != null) { 589 parent.requestDisallowInterceptTouchEvent(true); 590 } 591 mIsBeingDragged = true; 592 if (deltaX > 0) { 593 deltaX -= mTouchSlop; 594 } else { 595 deltaX += mTouchSlop; 596 } 597 } 598 if (mIsBeingDragged) { 599 // Scroll to follow the motion event 600 mLastMotionX = x; 601 602 final int oldX = mScrollX; 603 final int oldY = mScrollY; 604 final int range = getScrollRange(); 605 final int overscrollMode = getOverScrollMode(); 606 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 607 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 608 609 // Calling overScrollBy will call onOverScrolled, which 610 // calls onScrollChanged if applicable. 611 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 612 mOverscrollDistance, 0, true)) { 613 // Break our velocity if we hit a scroll barrier. 614 mVelocityTracker.clear(); 615 } 616 617 if (canOverscroll) { 618 final int pulledToX = oldX + deltaX; 619 if (pulledToX < 0) { 620 mEdgeGlowLeft.onPull((float) deltaX / getWidth(), 621 1.f - ev.getY(activePointerIndex) / getHeight()); 622 if (!mEdgeGlowRight.isFinished()) { 623 mEdgeGlowRight.onRelease(); 624 } 625 } else if (pulledToX > range) { 626 mEdgeGlowRight.onPull((float) deltaX / getWidth(), 627 ev.getY(activePointerIndex) / getHeight()); 628 if (!mEdgeGlowLeft.isFinished()) { 629 mEdgeGlowLeft.onRelease(); 630 } 631 } 632 if (mEdgeGlowLeft != null 633 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 634 postInvalidateOnAnimation(); 635 } 636 } 637 } 638 break; 639 case MotionEvent.ACTION_UP: 640 if (mIsBeingDragged) { 641 final VelocityTracker velocityTracker = mVelocityTracker; 642 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 643 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 644 645 if (getChildCount() > 0) { 646 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 647 fling(-initialVelocity); 648 } else { 649 if (mScroller.springBack(mScrollX, mScrollY, 0, 650 getScrollRange(), 0, 0)) { 651 postInvalidateOnAnimation(); 652 } 653 } 654 } 655 656 mActivePointerId = INVALID_POINTER; 657 mIsBeingDragged = false; 658 recycleVelocityTracker(); 659 660 if (mEdgeGlowLeft != null) { 661 mEdgeGlowLeft.onRelease(); 662 mEdgeGlowRight.onRelease(); 663 } 664 } 665 break; 666 case MotionEvent.ACTION_CANCEL: 667 if (mIsBeingDragged && getChildCount() > 0) { 668 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 669 postInvalidateOnAnimation(); 670 } 671 mActivePointerId = INVALID_POINTER; 672 mIsBeingDragged = false; 673 recycleVelocityTracker(); 674 675 if (mEdgeGlowLeft != null) { 676 mEdgeGlowLeft.onRelease(); 677 mEdgeGlowRight.onRelease(); 678 } 679 } 680 break; 681 case MotionEvent.ACTION_POINTER_UP: 682 onSecondaryPointerUp(ev); 683 break; 684 } 685 return true; 686 } 687 688 private void onSecondaryPointerUp(MotionEvent ev) { 689 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 690 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 691 final int pointerId = ev.getPointerId(pointerIndex); 692 if (pointerId == mActivePointerId) { 693 // This was our active pointer going up. Choose a new 694 // active pointer and adjust accordingly. 695 // TODO: Make this decision more intelligent. 696 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 697 mLastMotionX = (int) ev.getX(newPointerIndex); 698 mActivePointerId = ev.getPointerId(newPointerIndex); 699 if (mVelocityTracker != null) { 700 mVelocityTracker.clear(); 701 } 702 } 703 } 704 705 @Override 706 public boolean onGenericMotionEvent(MotionEvent event) { 707 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 708 switch (event.getAction()) { 709 case MotionEvent.ACTION_SCROLL: { 710 if (!mIsBeingDragged) { 711 final float hscroll; 712 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 713 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 714 } else { 715 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 716 } 717 if (hscroll != 0) { 718 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 719 final int range = getScrollRange(); 720 int oldScrollX = mScrollX; 721 int newScrollX = oldScrollX + delta; 722 if (newScrollX < 0) { 723 newScrollX = 0; 724 } else if (newScrollX > range) { 725 newScrollX = range; 726 } 727 if (newScrollX != oldScrollX) { 728 super.scrollTo(newScrollX, mScrollY); 729 return true; 730 } 731 } 732 } 733 } 734 } 735 } 736 return super.onGenericMotionEvent(event); 737 } 738 739 @Override 740 public boolean shouldDelayChildPressedState() { 741 return true; 742 } 743 744 @Override 745 protected void onOverScrolled(int scrollX, int scrollY, 746 boolean clampedX, boolean clampedY) { 747 // Treat animating scrolls differently; see #computeScroll() for why. 748 if (!mScroller.isFinished()) { 749 final int oldX = mScrollX; 750 final int oldY = mScrollY; 751 mScrollX = scrollX; 752 mScrollY = scrollY; 753 invalidateParentIfNeeded(); 754 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 755 if (clampedX) { 756 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 757 } 758 } else { 759 super.scrollTo(scrollX, scrollY); 760 } 761 762 awakenScrollBars(); 763 } 764 765 /** @hide */ 766 @Override 767 public boolean performAccessibilityActionInternal(int action, Bundle arguments) { 768 if (super.performAccessibilityActionInternal(action, arguments)) { 769 return true; 770 } 771 switch (action) { 772 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 773 if (!isEnabled()) { 774 return false; 775 } 776 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 777 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 778 if (targetScrollX != mScrollX) { 779 smoothScrollTo(targetScrollX, 0); 780 return true; 781 } 782 } return false; 783 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 784 if (!isEnabled()) { 785 return false; 786 } 787 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 788 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 789 if (targetScrollX != mScrollX) { 790 smoothScrollTo(targetScrollX, 0); 791 return true; 792 } 793 } return false; 794 } 795 return false; 796 } 797 798 /** @hide */ 799 @Override 800 public void onInitializeAccessibilityNodeInfoInternal(AccessibilityNodeInfo info) { 801 super.onInitializeAccessibilityNodeInfoInternal(info); 802 info.setClassName(HorizontalScrollView.class.getName()); 803 final int scrollRange = getScrollRange(); 804 if (scrollRange > 0) { 805 info.setScrollable(true); 806 if (isEnabled() && mScrollX > 0) { 807 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 808 } 809 if (isEnabled() && mScrollX < scrollRange) { 810 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 811 } 812 } 813 } 814 815 /** @hide */ 816 @Override 817 public void onInitializeAccessibilityEventInternal(AccessibilityEvent event) { 818 super.onInitializeAccessibilityEventInternal(event); 819 event.setClassName(HorizontalScrollView.class.getName()); 820 event.setScrollable(getScrollRange() > 0); 821 event.setScrollX(mScrollX); 822 event.setScrollY(mScrollY); 823 event.setMaxScrollX(getScrollRange()); 824 event.setMaxScrollY(mScrollY); 825 } 826 827 private int getScrollRange() { 828 int scrollRange = 0; 829 if (getChildCount() > 0) { 830 View child = getChildAt(0); 831 scrollRange = Math.max(0, 832 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 833 } 834 return scrollRange; 835 } 836 837 /** 838 * <p> 839 * Finds the next focusable component that fits in this View's bounds 840 * (excluding fading edges) pretending that this View's left is located at 841 * the parameter left. 842 * </p> 843 * 844 * @param leftFocus look for a candidate is the one at the left of the bounds 845 * if leftFocus is true, or at the right of the bounds if leftFocus 846 * is false 847 * @param left the left offset of the bounds in which a focusable must be 848 * found (the fading edge is assumed to start at this position) 849 * @param preferredFocusable the View that has highest priority and will be 850 * returned if it is within my bounds (null is valid) 851 * @return the next focusable component in the bounds or null if none can be found 852 */ 853 private View findFocusableViewInMyBounds(final boolean leftFocus, 854 final int left, View preferredFocusable) { 855 /* 856 * The fading edge's transparent side should be considered for focus 857 * since it's mostly visible, so we divide the actual fading edge length 858 * by 2. 859 */ 860 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 861 final int leftWithoutFadingEdge = left + fadingEdgeLength; 862 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 863 864 if ((preferredFocusable != null) 865 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 866 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 867 return preferredFocusable; 868 } 869 870 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 871 rightWithoutFadingEdge); 872 } 873 874 /** 875 * <p> 876 * Finds the next focusable component that fits in the specified bounds. 877 * </p> 878 * 879 * @param leftFocus look for a candidate is the one at the left of the bounds 880 * if leftFocus is true, or at the right of the bounds if 881 * leftFocus is false 882 * @param left the left offset of the bounds in which a focusable must be 883 * found 884 * @param right the right offset of the bounds in which a focusable must 885 * be found 886 * @return the next focusable component in the bounds or null if none can 887 * be found 888 */ 889 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 890 891 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 892 View focusCandidate = null; 893 894 /* 895 * A fully contained focusable is one where its left is below the bound's 896 * left, and its right is above the bound's right. A partially 897 * contained focusable is one where some part of it is within the 898 * bounds, but it also has some part that is not within bounds. A fully contained 899 * focusable is preferred to a partially contained focusable. 900 */ 901 boolean foundFullyContainedFocusable = false; 902 903 int count = focusables.size(); 904 for (int i = 0; i < count; i++) { 905 View view = focusables.get(i); 906 int viewLeft = view.getLeft(); 907 int viewRight = view.getRight(); 908 909 if (left < viewRight && viewLeft < right) { 910 /* 911 * the focusable is in the target area, it is a candidate for 912 * focusing 913 */ 914 915 final boolean viewIsFullyContained = (left < viewLeft) && 916 (viewRight < right); 917 918 if (focusCandidate == null) { 919 /* No candidate, take this one */ 920 focusCandidate = view; 921 foundFullyContainedFocusable = viewIsFullyContained; 922 } else { 923 final boolean viewIsCloserToBoundary = 924 (leftFocus && viewLeft < focusCandidate.getLeft()) || 925 (!leftFocus && viewRight > focusCandidate.getRight()); 926 927 if (foundFullyContainedFocusable) { 928 if (viewIsFullyContained && viewIsCloserToBoundary) { 929 /* 930 * We're dealing with only fully contained views, so 931 * it has to be closer to the boundary to beat our 932 * candidate 933 */ 934 focusCandidate = view; 935 } 936 } else { 937 if (viewIsFullyContained) { 938 /* Any fully contained view beats a partially contained view */ 939 focusCandidate = view; 940 foundFullyContainedFocusable = true; 941 } else if (viewIsCloserToBoundary) { 942 /* 943 * Partially contained view beats another partially 944 * contained view if it's closer 945 */ 946 focusCandidate = view; 947 } 948 } 949 } 950 } 951 } 952 953 return focusCandidate; 954 } 955 956 /** 957 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 958 * method will scroll the view by one page left or right and give the focus 959 * to the leftmost/rightmost component in the new visible area. If no 960 * component is a good candidate for focus, this scrollview reclaims the 961 * focus.</p> 962 * 963 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 964 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 965 * to go one page right 966 * @return true if the key event is consumed by this method, false otherwise 967 */ 968 public boolean pageScroll(int direction) { 969 boolean right = direction == View.FOCUS_RIGHT; 970 int width = getWidth(); 971 972 if (right) { 973 mTempRect.left = getScrollX() + width; 974 int count = getChildCount(); 975 if (count > 0) { 976 View view = getChildAt(0); 977 if (mTempRect.left + width > view.getRight()) { 978 mTempRect.left = view.getRight() - width; 979 } 980 } 981 } else { 982 mTempRect.left = getScrollX() - width; 983 if (mTempRect.left < 0) { 984 mTempRect.left = 0; 985 } 986 } 987 mTempRect.right = mTempRect.left + width; 988 989 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 990 } 991 992 /** 993 * <p>Handles scrolling in response to a "home/end" shortcut press. This 994 * method will scroll the view to the left or right and give the focus 995 * to the leftmost/rightmost component in the new visible area. If no 996 * component is a good candidate for focus, this scrollview reclaims the 997 * focus.</p> 998 * 999 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1000 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 1001 * to go the right 1002 * @return true if the key event is consumed by this method, false otherwise 1003 */ 1004 public boolean fullScroll(int direction) { 1005 boolean right = direction == View.FOCUS_RIGHT; 1006 int width = getWidth(); 1007 1008 mTempRect.left = 0; 1009 mTempRect.right = width; 1010 1011 if (right) { 1012 int count = getChildCount(); 1013 if (count > 0) { 1014 View view = getChildAt(0); 1015 mTempRect.right = view.getRight(); 1016 mTempRect.left = mTempRect.right - width; 1017 } 1018 } 1019 1020 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 1021 } 1022 1023 /** 1024 * <p>Scrolls the view to make the area defined by <code>left</code> and 1025 * <code>right</code> visible. This method attempts to give the focus 1026 * to a component visible in this area. If no component can be focused in 1027 * the new visible area, the focus is reclaimed by this scrollview.</p> 1028 * 1029 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1030 * to go left {@link android.view.View#FOCUS_RIGHT} to right 1031 * @param left the left offset of the new area to be made visible 1032 * @param right the right offset of the new area to be made visible 1033 * @return true if the key event is consumed by this method, false otherwise 1034 */ 1035 private boolean scrollAndFocus(int direction, int left, int right) { 1036 boolean handled = true; 1037 1038 int width = getWidth(); 1039 int containerLeft = getScrollX(); 1040 int containerRight = containerLeft + width; 1041 boolean goLeft = direction == View.FOCUS_LEFT; 1042 1043 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1044 if (newFocused == null) { 1045 newFocused = this; 1046 } 1047 1048 if (left >= containerLeft && right <= containerRight) { 1049 handled = false; 1050 } else { 1051 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1052 doScrollX(delta); 1053 } 1054 1055 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1056 1057 return handled; 1058 } 1059 1060 /** 1061 * Handle scrolling in response to a left or right arrow click. 1062 * 1063 * @param direction The direction corresponding to the arrow key that was 1064 * pressed 1065 * @return True if we consumed the event, false otherwise 1066 */ 1067 public boolean arrowScroll(int direction) { 1068 1069 View currentFocused = findFocus(); 1070 if (currentFocused == this) currentFocused = null; 1071 1072 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1073 1074 final int maxJump = getMaxScrollAmount(); 1075 1076 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1077 nextFocused.getDrawingRect(mTempRect); 1078 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1079 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1080 doScrollX(scrollDelta); 1081 nextFocused.requestFocus(direction); 1082 } else { 1083 // no new focus 1084 int scrollDelta = maxJump; 1085 1086 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1087 scrollDelta = getScrollX(); 1088 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1089 1090 int daRight = getChildAt(0).getRight(); 1091 1092 int screenRight = getScrollX() + getWidth(); 1093 1094 if (daRight - screenRight < maxJump) { 1095 scrollDelta = daRight - screenRight; 1096 } 1097 } 1098 if (scrollDelta == 0) { 1099 return false; 1100 } 1101 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1102 } 1103 1104 if (currentFocused != null && currentFocused.isFocused() 1105 && isOffScreen(currentFocused)) { 1106 // previously focused item still has focus and is off screen, give 1107 // it up (take it back to ourselves) 1108 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1109 // sure to 1110 // get it) 1111 final int descendantFocusability = getDescendantFocusability(); // save 1112 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1113 requestFocus(); 1114 setDescendantFocusability(descendantFocusability); // restore 1115 } 1116 return true; 1117 } 1118 1119 /** 1120 * @return whether the descendant of this scroll view is scrolled off 1121 * screen. 1122 */ 1123 private boolean isOffScreen(View descendant) { 1124 return !isWithinDeltaOfScreen(descendant, 0); 1125 } 1126 1127 /** 1128 * @return whether the descendant of this scroll view is within delta 1129 * pixels of being on the screen. 1130 */ 1131 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1132 descendant.getDrawingRect(mTempRect); 1133 offsetDescendantRectToMyCoords(descendant, mTempRect); 1134 1135 return (mTempRect.right + delta) >= getScrollX() 1136 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1137 } 1138 1139 /** 1140 * Smooth scroll by a X delta 1141 * 1142 * @param delta the number of pixels to scroll by on the X axis 1143 */ 1144 private void doScrollX(int delta) { 1145 if (delta != 0) { 1146 if (mSmoothScrollingEnabled) { 1147 smoothScrollBy(delta, 0); 1148 } else { 1149 scrollBy(delta, 0); 1150 } 1151 } 1152 } 1153 1154 /** 1155 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1156 * 1157 * @param dx the number of pixels to scroll by on the X axis 1158 * @param dy the number of pixels to scroll by on the Y axis 1159 */ 1160 public final void smoothScrollBy(int dx, int dy) { 1161 if (getChildCount() == 0) { 1162 // Nothing to do. 1163 return; 1164 } 1165 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1166 if (duration > ANIMATED_SCROLL_GAP) { 1167 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1168 final int right = getChildAt(0).getWidth(); 1169 final int maxX = Math.max(0, right - width); 1170 final int scrollX = mScrollX; 1171 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1172 1173 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1174 postInvalidateOnAnimation(); 1175 } else { 1176 if (!mScroller.isFinished()) { 1177 mScroller.abortAnimation(); 1178 } 1179 scrollBy(dx, dy); 1180 } 1181 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1182 } 1183 1184 /** 1185 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1186 * 1187 * @param x the position where to scroll on the X axis 1188 * @param y the position where to scroll on the Y axis 1189 */ 1190 public final void smoothScrollTo(int x, int y) { 1191 smoothScrollBy(x - mScrollX, y - mScrollY); 1192 } 1193 1194 /** 1195 * <p>The scroll range of a scroll view is the overall width of all of its 1196 * children.</p> 1197 */ 1198 @Override 1199 protected int computeHorizontalScrollRange() { 1200 final int count = getChildCount(); 1201 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1202 if (count == 0) { 1203 return contentWidth; 1204 } 1205 1206 int scrollRange = getChildAt(0).getRight(); 1207 final int scrollX = mScrollX; 1208 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1209 if (scrollX < 0) { 1210 scrollRange -= scrollX; 1211 } else if (scrollX > overscrollRight) { 1212 scrollRange += scrollX - overscrollRight; 1213 } 1214 1215 return scrollRange; 1216 } 1217 1218 @Override 1219 protected int computeHorizontalScrollOffset() { 1220 return Math.max(0, super.computeHorizontalScrollOffset()); 1221 } 1222 1223 @Override 1224 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1225 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1226 1227 int childWidthMeasureSpec; 1228 int childHeightMeasureSpec; 1229 1230 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1231 + mPaddingBottom, lp.height); 1232 1233 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1234 1235 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1236 } 1237 1238 @Override 1239 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1240 int parentHeightMeasureSpec, int heightUsed) { 1241 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1242 1243 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1244 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1245 + heightUsed, lp.height); 1246 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1247 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1248 1249 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1250 } 1251 1252 @Override 1253 public void computeScroll() { 1254 if (mScroller.computeScrollOffset()) { 1255 // This is called at drawing time by ViewGroup. We don't want to 1256 // re-show the scrollbars at this point, which scrollTo will do, 1257 // so we replicate most of scrollTo here. 1258 // 1259 // It's a little odd to call onScrollChanged from inside the drawing. 1260 // 1261 // It is, except when you remember that computeScroll() is used to 1262 // animate scrolling. So unless we want to defer the onScrollChanged() 1263 // until the end of the animated scrolling, we don't really have a 1264 // choice here. 1265 // 1266 // I agree. The alternative, which I think would be worse, is to post 1267 // something and tell the subclasses later. This is bad because there 1268 // will be a window where mScrollX/Y is different from what the app 1269 // thinks it is. 1270 // 1271 int oldX = mScrollX; 1272 int oldY = mScrollY; 1273 int x = mScroller.getCurrX(); 1274 int y = mScroller.getCurrY(); 1275 1276 if (oldX != x || oldY != y) { 1277 final int range = getScrollRange(); 1278 final int overscrollMode = getOverScrollMode(); 1279 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1280 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1281 1282 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1283 mOverflingDistance, 0, false); 1284 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1285 1286 if (canOverscroll) { 1287 if (x < 0 && oldX >= 0) { 1288 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1289 } else if (x > range && oldX <= range) { 1290 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1291 } 1292 } 1293 } 1294 1295 if (!awakenScrollBars()) { 1296 postInvalidateOnAnimation(); 1297 } 1298 } 1299 } 1300 1301 /** 1302 * Scrolls the view to the given child. 1303 * 1304 * @param child the View to scroll to 1305 */ 1306 private void scrollToChild(View child) { 1307 child.getDrawingRect(mTempRect); 1308 1309 /* Offset from child's local coordinates to ScrollView coordinates */ 1310 offsetDescendantRectToMyCoords(child, mTempRect); 1311 1312 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1313 1314 if (scrollDelta != 0) { 1315 scrollBy(scrollDelta, 0); 1316 } 1317 } 1318 1319 /** 1320 * If rect is off screen, scroll just enough to get it (or at least the 1321 * first screen size chunk of it) on screen. 1322 * 1323 * @param rect The rectangle. 1324 * @param immediate True to scroll immediately without animation 1325 * @return true if scrolling was performed 1326 */ 1327 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1328 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1329 final boolean scroll = delta != 0; 1330 if (scroll) { 1331 if (immediate) { 1332 scrollBy(delta, 0); 1333 } else { 1334 smoothScrollBy(delta, 0); 1335 } 1336 } 1337 return scroll; 1338 } 1339 1340 /** 1341 * Compute the amount to scroll in the X direction in order to get 1342 * a rectangle completely on the screen (or, if taller than the screen, 1343 * at least the first screen size chunk of it). 1344 * 1345 * @param rect The rect. 1346 * @return The scroll delta. 1347 */ 1348 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1349 if (getChildCount() == 0) return 0; 1350 1351 int width = getWidth(); 1352 int screenLeft = getScrollX(); 1353 int screenRight = screenLeft + width; 1354 1355 int fadingEdge = getHorizontalFadingEdgeLength(); 1356 1357 // leave room for left fading edge as long as rect isn't at very left 1358 if (rect.left > 0) { 1359 screenLeft += fadingEdge; 1360 } 1361 1362 // leave room for right fading edge as long as rect isn't at very right 1363 if (rect.right < getChildAt(0).getWidth()) { 1364 screenRight -= fadingEdge; 1365 } 1366 1367 int scrollXDelta = 0; 1368 1369 if (rect.right > screenRight && rect.left > screenLeft) { 1370 // need to move right to get it in view: move right just enough so 1371 // that the entire rectangle is in view (or at least the first 1372 // screen size chunk). 1373 1374 if (rect.width() > width) { 1375 // just enough to get screen size chunk on 1376 scrollXDelta += (rect.left - screenLeft); 1377 } else { 1378 // get entire rect at right of screen 1379 scrollXDelta += (rect.right - screenRight); 1380 } 1381 1382 // make sure we aren't scrolling beyond the end of our content 1383 int right = getChildAt(0).getRight(); 1384 int distanceToRight = right - screenRight; 1385 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1386 1387 } else if (rect.left < screenLeft && rect.right < screenRight) { 1388 // need to move right to get it in view: move right just enough so that 1389 // entire rectangle is in view (or at least the first screen 1390 // size chunk of it). 1391 1392 if (rect.width() > width) { 1393 // screen size chunk 1394 scrollXDelta -= (screenRight - rect.right); 1395 } else { 1396 // entire rect at left 1397 scrollXDelta -= (screenLeft - rect.left); 1398 } 1399 1400 // make sure we aren't scrolling any further than the left our content 1401 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1402 } 1403 return scrollXDelta; 1404 } 1405 1406 @Override 1407 public void requestChildFocus(View child, View focused) { 1408 if (!mIsLayoutDirty) { 1409 scrollToChild(focused); 1410 } else { 1411 // The child may not be laid out yet, we can't compute the scroll yet 1412 mChildToScrollTo = focused; 1413 } 1414 super.requestChildFocus(child, focused); 1415 } 1416 1417 1418 /** 1419 * When looking for focus in children of a scroll view, need to be a little 1420 * more careful not to give focus to something that is scrolled off screen. 1421 * 1422 * This is more expensive than the default {@link android.view.ViewGroup} 1423 * implementation, otherwise this behavior might have been made the default. 1424 */ 1425 @Override 1426 protected boolean onRequestFocusInDescendants(int direction, 1427 Rect previouslyFocusedRect) { 1428 1429 // convert from forward / backward notation to up / down / left / right 1430 // (ugh). 1431 if (direction == View.FOCUS_FORWARD) { 1432 direction = View.FOCUS_RIGHT; 1433 } else if (direction == View.FOCUS_BACKWARD) { 1434 direction = View.FOCUS_LEFT; 1435 } 1436 1437 final View nextFocus = previouslyFocusedRect == null ? 1438 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1439 FocusFinder.getInstance().findNextFocusFromRect(this, 1440 previouslyFocusedRect, direction); 1441 1442 if (nextFocus == null) { 1443 return false; 1444 } 1445 1446 if (isOffScreen(nextFocus)) { 1447 return false; 1448 } 1449 1450 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1451 } 1452 1453 @Override 1454 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1455 boolean immediate) { 1456 // offset into coordinate space of this scroll view 1457 rectangle.offset(child.getLeft() - child.getScrollX(), 1458 child.getTop() - child.getScrollY()); 1459 1460 return scrollToChildRect(rectangle, immediate); 1461 } 1462 1463 @Override 1464 public void requestLayout() { 1465 mIsLayoutDirty = true; 1466 super.requestLayout(); 1467 } 1468 1469 @Override 1470 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1471 int childWidth = 0; 1472 int childMargins = 0; 1473 1474 if (getChildCount() > 0) { 1475 childWidth = getChildAt(0).getMeasuredWidth(); 1476 LayoutParams childParams = (LayoutParams) getChildAt(0).getLayoutParams(); 1477 childMargins = childParams.leftMargin + childParams.rightMargin; 1478 } 1479 1480 final int available = r - l - getPaddingLeftWithForeground() - 1481 getPaddingRightWithForeground() - childMargins; 1482 1483 final boolean forceLeftGravity = (childWidth > available); 1484 1485 layoutChildren(l, t, r, b, forceLeftGravity); 1486 1487 mIsLayoutDirty = false; 1488 // Give a child focus if it needs it 1489 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1490 scrollToChild(mChildToScrollTo); 1491 } 1492 mChildToScrollTo = null; 1493 1494 if (!isLaidOut()) { 1495 final int scrollRange = Math.max(0, 1496 childWidth - (r - l - mPaddingLeft - mPaddingRight)); 1497 if (mSavedState != null) { 1498 if (isLayoutRtl() == mSavedState.isLayoutRtl) { 1499 mScrollX = mSavedState.scrollPosition; 1500 } else { 1501 mScrollX = scrollRange - mSavedState.scrollPosition; 1502 } 1503 mSavedState = null; 1504 } else { 1505 if (isLayoutRtl()) { 1506 mScrollX = scrollRange - mScrollX; 1507 } // mScrollX default value is "0" for LTR 1508 } 1509 // Don't forget to clamp 1510 if (mScrollX > scrollRange) { 1511 mScrollX = scrollRange; 1512 } else if (mScrollX < 0) { 1513 mScrollX = 0; 1514 } 1515 } 1516 1517 // Calling this with the present values causes it to re-claim them 1518 scrollTo(mScrollX, mScrollY); 1519 } 1520 1521 @Override 1522 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1523 super.onSizeChanged(w, h, oldw, oldh); 1524 1525 View currentFocused = findFocus(); 1526 if (null == currentFocused || this == currentFocused) 1527 return; 1528 1529 final int maxJump = mRight - mLeft; 1530 1531 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1532 currentFocused.getDrawingRect(mTempRect); 1533 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1534 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1535 doScrollX(scrollDelta); 1536 } 1537 } 1538 1539 /** 1540 * Return true if child is a descendant of parent, (or equal to the parent). 1541 */ 1542 private static boolean isViewDescendantOf(View child, View parent) { 1543 if (child == parent) { 1544 return true; 1545 } 1546 1547 final ViewParent theParent = child.getParent(); 1548 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1549 } 1550 1551 /** 1552 * Fling the scroll view 1553 * 1554 * @param velocityX The initial velocity in the X direction. Positive 1555 * numbers mean that the finger/cursor is moving down the screen, 1556 * which means we want to scroll towards the left. 1557 */ 1558 public void fling(int velocityX) { 1559 if (getChildCount() > 0) { 1560 int width = getWidth() - mPaddingRight - mPaddingLeft; 1561 int right = getChildAt(0).getWidth(); 1562 1563 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1564 Math.max(0, right - width), 0, 0, width/2, 0); 1565 1566 final boolean movingRight = velocityX > 0; 1567 1568 View currentFocused = findFocus(); 1569 View newFocused = findFocusableViewInMyBounds(movingRight, 1570 mScroller.getFinalX(), currentFocused); 1571 1572 if (newFocused == null) { 1573 newFocused = this; 1574 } 1575 1576 if (newFocused != currentFocused) { 1577 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1578 } 1579 1580 postInvalidateOnAnimation(); 1581 } 1582 } 1583 1584 /** 1585 * {@inheritDoc} 1586 * 1587 * <p>This version also clamps the scrolling to the bounds of our child. 1588 */ 1589 @Override 1590 public void scrollTo(int x, int y) { 1591 // we rely on the fact the View.scrollBy calls scrollTo. 1592 if (getChildCount() > 0) { 1593 View child = getChildAt(0); 1594 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1595 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1596 if (x != mScrollX || y != mScrollY) { 1597 super.scrollTo(x, y); 1598 } 1599 } 1600 } 1601 1602 @Override 1603 public void setOverScrollMode(int mode) { 1604 if (mode != OVER_SCROLL_NEVER) { 1605 if (mEdgeGlowLeft == null) { 1606 Context context = getContext(); 1607 mEdgeGlowLeft = new EdgeEffect(context); 1608 mEdgeGlowRight = new EdgeEffect(context); 1609 } 1610 } else { 1611 mEdgeGlowLeft = null; 1612 mEdgeGlowRight = null; 1613 } 1614 super.setOverScrollMode(mode); 1615 } 1616 1617 @SuppressWarnings({"SuspiciousNameCombination"}) 1618 @Override 1619 public void draw(Canvas canvas) { 1620 super.draw(canvas); 1621 if (mEdgeGlowLeft != null) { 1622 final int scrollX = mScrollX; 1623 if (!mEdgeGlowLeft.isFinished()) { 1624 final int restoreCount = canvas.save(); 1625 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1626 1627 canvas.rotate(270); 1628 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1629 mEdgeGlowLeft.setSize(height, getWidth()); 1630 if (mEdgeGlowLeft.draw(canvas)) { 1631 postInvalidateOnAnimation(); 1632 } 1633 canvas.restoreToCount(restoreCount); 1634 } 1635 if (!mEdgeGlowRight.isFinished()) { 1636 final int restoreCount = canvas.save(); 1637 final int width = getWidth(); 1638 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1639 1640 canvas.rotate(90); 1641 canvas.translate(-mPaddingTop, 1642 -(Math.max(getScrollRange(), scrollX) + width)); 1643 mEdgeGlowRight.setSize(height, width); 1644 if (mEdgeGlowRight.draw(canvas)) { 1645 postInvalidateOnAnimation(); 1646 } 1647 canvas.restoreToCount(restoreCount); 1648 } 1649 } 1650 } 1651 1652 private static int clamp(int n, int my, int child) { 1653 if (my >= child || n < 0) { 1654 return 0; 1655 } 1656 if ((my + n) > child) { 1657 return child - my; 1658 } 1659 return n; 1660 } 1661 1662 @Override 1663 protected void onRestoreInstanceState(Parcelable state) { 1664 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1665 // Some old apps reused IDs in ways they shouldn't have. 1666 // Don't break them, but they don't get scroll state restoration. 1667 super.onRestoreInstanceState(state); 1668 return; 1669 } 1670 SavedState ss = (SavedState) state; 1671 super.onRestoreInstanceState(ss.getSuperState()); 1672 mSavedState = ss; 1673 requestLayout(); 1674 } 1675 1676 @Override 1677 protected Parcelable onSaveInstanceState() { 1678 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1679 // Some old apps reused IDs in ways they shouldn't have. 1680 // Don't break them, but they don't get scroll state restoration. 1681 return super.onSaveInstanceState(); 1682 } 1683 Parcelable superState = super.onSaveInstanceState(); 1684 SavedState ss = new SavedState(superState); 1685 ss.scrollPosition = mScrollX; 1686 ss.isLayoutRtl = isLayoutRtl(); 1687 return ss; 1688 } 1689 1690 static class SavedState extends BaseSavedState { 1691 public int scrollPosition; 1692 public boolean isLayoutRtl; 1693 1694 SavedState(Parcelable superState) { 1695 super(superState); 1696 } 1697 1698 public SavedState(Parcel source) { 1699 super(source); 1700 scrollPosition = source.readInt(); 1701 isLayoutRtl = (source.readInt() == 0) ? true : false; 1702 } 1703 1704 @Override 1705 public void writeToParcel(Parcel dest, int flags) { 1706 super.writeToParcel(dest, flags); 1707 dest.writeInt(scrollPosition); 1708 dest.writeInt(isLayoutRtl ? 1 : 0); 1709 } 1710 1711 @Override 1712 public String toString() { 1713 return "HorizontalScrollView.SavedState{" 1714 + Integer.toHexString(System.identityHashCode(this)) 1715 + " scrollPosition=" + scrollPosition 1716 + " isLayoutRtl=" + isLayoutRtl + "}"; 1717 } 1718 1719 public static final Parcelable.Creator<SavedState> CREATOR 1720 = new Parcelable.Creator<SavedState>() { 1721 public SavedState createFromParcel(Parcel in) { 1722 return new SavedState(in); 1723 } 1724 1725 public SavedState[] newArray(int size) { 1726 return new SavedState[size]; 1727 } 1728 }; 1729 } 1730} 1731