HorizontalScrollView.java revision 08c7116ab9cd04ad6dd3c04aa1017237e7f409ac
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.Build; 24import android.os.Bundle; 25import android.os.Parcel; 26import android.os.Parcelable; 27import android.util.AttributeSet; 28import android.util.Log; 29import android.view.FocusFinder; 30import android.view.InputDevice; 31import android.view.KeyEvent; 32import android.view.MotionEvent; 33import android.view.VelocityTracker; 34import android.view.View; 35import android.view.ViewConfiguration; 36import android.view.ViewDebug; 37import android.view.ViewGroup; 38import android.view.ViewParent; 39import android.view.accessibility.AccessibilityEvent; 40import android.view.accessibility.AccessibilityNodeInfo; 41import android.view.animation.AnimationUtils; 42 43import java.util.List; 44 45/** 46 * Layout container for a view hierarchy that can be scrolled by the user, 47 * allowing it to be larger than the physical display. A HorizontalScrollView 48 * is a {@link FrameLayout}, meaning you should place one child in it 49 * containing the entire contents to scroll; this child may itself be a layout 50 * manager with a complex hierarchy of objects. A child that is often used 51 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 52 * array of top-level items that the user can scroll through. 53 * 54 * <p>The {@link TextView} class also 55 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 56 * using the two together is possible to achieve the effect of a text view 57 * within a larger container. 58 * 59 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 60 * use either {@link ScrollView} or {@link ListView}. 61 * 62 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 63 */ 64public class HorizontalScrollView extends FrameLayout { 65 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 66 67 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 68 69 private static final String TAG = "HorizontalScrollView"; 70 71 private long mLastScroll; 72 73 private final Rect mTempRect = new Rect(); 74 private OverScroller mScroller; 75 private EdgeEffect mEdgeGlowLeft; 76 private EdgeEffect mEdgeGlowRight; 77 78 /** 79 * Position of the last motion event. 80 */ 81 private int mLastMotionX; 82 83 /** 84 * True when the layout has changed but the traversal has not come through yet. 85 * Ideally the view hierarchy would keep track of this for us. 86 */ 87 private boolean mIsLayoutDirty = true; 88 89 /** 90 * The child to give focus to in the event that a child has requested focus while the 91 * layout is dirty. This prevents the scroll from being wrong if the child has not been 92 * laid out before requesting focus. 93 */ 94 private View mChildToScrollTo = null; 95 96 /** 97 * True if the user is currently dragging this ScrollView around. This is 98 * not the same as 'is being flinged', which can be checked by 99 * mScroller.isFinished() (flinging begins when the user lifts his finger). 100 */ 101 private boolean mIsBeingDragged = false; 102 103 /** 104 * Determines speed during touch scrolling 105 */ 106 private VelocityTracker mVelocityTracker; 107 108 /** 109 * When set to true, the scroll view measure its child to make it fill the currently 110 * visible area. 111 */ 112 @ViewDebug.ExportedProperty(category = "layout") 113 private boolean mFillViewport; 114 115 /** 116 * Whether arrow scrolling is animated. 117 */ 118 private boolean mSmoothScrollingEnabled = true; 119 120 private int mTouchSlop; 121 private int mMinimumVelocity; 122 private int mMaximumVelocity; 123 124 private int mOverscrollDistance; 125 private int mOverflingDistance; 126 127 /** 128 * ID of the active pointer. This is used to retain consistency during 129 * drags/flings if multiple pointers are used. 130 */ 131 private int mActivePointerId = INVALID_POINTER; 132 133 /** 134 * Sentinel value for no current active pointer. 135 * Used by {@link #mActivePointerId}. 136 */ 137 private static final int INVALID_POINTER = -1; 138 139 private SavedState mSavedState; 140 141 public HorizontalScrollView(Context context) { 142 this(context, null); 143 } 144 145 public HorizontalScrollView(Context context, AttributeSet attrs) { 146 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 147 } 148 149 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyleAttr) { 150 this(context, attrs, defStyleAttr, 0); 151 } 152 153 public HorizontalScrollView( 154 Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { 155 super(context, attrs, defStyleAttr, defStyleRes); 156 initScrollView(); 157 158 final TypedArray a = context.obtainStyledAttributes( 159 attrs, android.R.styleable.HorizontalScrollView, defStyleAttr, defStyleRes); 160 161 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 162 163 a.recycle(); 164 } 165 166 @Override 167 protected float getLeftFadingEdgeStrength() { 168 if (getChildCount() == 0) { 169 return 0.0f; 170 } 171 172 final int length = getHorizontalFadingEdgeLength(); 173 if (mScrollX < length) { 174 return mScrollX / (float) length; 175 } 176 177 return 1.0f; 178 } 179 180 @Override 181 protected float getRightFadingEdgeStrength() { 182 if (getChildCount() == 0) { 183 return 0.0f; 184 } 185 186 final int length = getHorizontalFadingEdgeLength(); 187 final int rightEdge = getWidth() - mPaddingRight; 188 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 189 if (span < length) { 190 return span / (float) length; 191 } 192 193 return 1.0f; 194 } 195 196 /** 197 * @return The maximum amount this scroll view will scroll in response to 198 * an arrow event. 199 */ 200 public int getMaxScrollAmount() { 201 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 202 } 203 204 205 private void initScrollView() { 206 mScroller = new OverScroller(getContext()); 207 setFocusable(true); 208 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 209 setWillNotDraw(false); 210 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 211 mTouchSlop = configuration.getScaledTouchSlop(); 212 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 213 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 214 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 215 mOverflingDistance = configuration.getScaledOverflingDistance(); 216 } 217 218 @Override 219 public void addView(View child) { 220 if (getChildCount() > 0) { 221 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 222 } 223 224 super.addView(child); 225 } 226 227 @Override 228 public void addView(View child, int index) { 229 if (getChildCount() > 0) { 230 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 231 } 232 233 super.addView(child, index); 234 } 235 236 @Override 237 public void addView(View child, ViewGroup.LayoutParams params) { 238 if (getChildCount() > 0) { 239 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 240 } 241 242 super.addView(child, params); 243 } 244 245 @Override 246 public void addView(View child, int index, ViewGroup.LayoutParams params) { 247 if (getChildCount() > 0) { 248 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 249 } 250 251 super.addView(child, index, params); 252 } 253 254 /** 255 * @return Returns true this HorizontalScrollView can be scrolled 256 */ 257 private boolean canScroll() { 258 View child = getChildAt(0); 259 if (child != null) { 260 int childWidth = child.getWidth(); 261 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 262 } 263 return false; 264 } 265 266 /** 267 * Indicates whether this HorizontalScrollView's content is stretched to 268 * fill the viewport. 269 * 270 * @return True if the content fills the viewport, false otherwise. 271 * 272 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 273 */ 274 public boolean isFillViewport() { 275 return mFillViewport; 276 } 277 278 /** 279 * Indicates this HorizontalScrollView whether it should stretch its content width 280 * to fill the viewport or not. 281 * 282 * @param fillViewport True to stretch the content's width to the viewport's 283 * boundaries, false otherwise. 284 * 285 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 286 */ 287 public void setFillViewport(boolean fillViewport) { 288 if (fillViewport != mFillViewport) { 289 mFillViewport = fillViewport; 290 requestLayout(); 291 } 292 } 293 294 /** 295 * @return Whether arrow scrolling will animate its transition. 296 */ 297 public boolean isSmoothScrollingEnabled() { 298 return mSmoothScrollingEnabled; 299 } 300 301 /** 302 * Set whether arrow scrolling will animate its transition. 303 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 304 */ 305 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 306 mSmoothScrollingEnabled = smoothScrollingEnabled; 307 } 308 309 @Override 310 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 311 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 312 313 if (!mFillViewport) { 314 return; 315 } 316 317 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 318 if (widthMode == MeasureSpec.UNSPECIFIED) { 319 return; 320 } 321 322 if (getChildCount() > 0) { 323 final View child = getChildAt(0); 324 int width = getMeasuredWidth(); 325 if (child.getMeasuredWidth() < width) { 326 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 327 328 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 329 + mPaddingBottom, lp.height); 330 width -= mPaddingLeft; 331 width -= mPaddingRight; 332 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 333 334 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 335 } 336 } 337 } 338 339 @Override 340 public boolean dispatchKeyEvent(KeyEvent event) { 341 // Let the focused view and/or our descendants get the key first 342 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 343 } 344 345 /** 346 * You can call this function yourself to have the scroll view perform 347 * scrolling from a key event, just as if the event had been dispatched to 348 * it by the view hierarchy. 349 * 350 * @param event The key event to execute. 351 * @return Return true if the event was handled, else false. 352 */ 353 public boolean executeKeyEvent(KeyEvent event) { 354 mTempRect.setEmpty(); 355 356 if (!canScroll()) { 357 if (isFocused()) { 358 View currentFocused = findFocus(); 359 if (currentFocused == this) currentFocused = null; 360 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 361 currentFocused, View.FOCUS_RIGHT); 362 return nextFocused != null && nextFocused != this && 363 nextFocused.requestFocus(View.FOCUS_RIGHT); 364 } 365 return false; 366 } 367 368 boolean handled = false; 369 if (event.getAction() == KeyEvent.ACTION_DOWN) { 370 switch (event.getKeyCode()) { 371 case KeyEvent.KEYCODE_DPAD_LEFT: 372 if (!event.isAltPressed()) { 373 handled = arrowScroll(View.FOCUS_LEFT); 374 } else { 375 handled = fullScroll(View.FOCUS_LEFT); 376 } 377 break; 378 case KeyEvent.KEYCODE_DPAD_RIGHT: 379 if (!event.isAltPressed()) { 380 handled = arrowScroll(View.FOCUS_RIGHT); 381 } else { 382 handled = fullScroll(View.FOCUS_RIGHT); 383 } 384 break; 385 case KeyEvent.KEYCODE_SPACE: 386 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 387 break; 388 } 389 } 390 391 return handled; 392 } 393 394 private boolean inChild(int x, int y) { 395 if (getChildCount() > 0) { 396 final int scrollX = mScrollX; 397 final View child = getChildAt(0); 398 return !(y < child.getTop() 399 || y >= child.getBottom() 400 || x < child.getLeft() - scrollX 401 || x >= child.getRight() - scrollX); 402 } 403 return false; 404 } 405 406 private void initOrResetVelocityTracker() { 407 if (mVelocityTracker == null) { 408 mVelocityTracker = VelocityTracker.obtain(); 409 } else { 410 mVelocityTracker.clear(); 411 } 412 } 413 414 private void initVelocityTrackerIfNotExists() { 415 if (mVelocityTracker == null) { 416 mVelocityTracker = VelocityTracker.obtain(); 417 } 418 } 419 420 private void recycleVelocityTracker() { 421 if (mVelocityTracker != null) { 422 mVelocityTracker.recycle(); 423 mVelocityTracker = null; 424 } 425 } 426 427 @Override 428 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 429 if (disallowIntercept) { 430 recycleVelocityTracker(); 431 } 432 super.requestDisallowInterceptTouchEvent(disallowIntercept); 433 } 434 435 @Override 436 public boolean onInterceptTouchEvent(MotionEvent ev) { 437 /* 438 * This method JUST determines whether we want to intercept the motion. 439 * If we return true, onMotionEvent will be called and we do the actual 440 * scrolling there. 441 */ 442 443 /* 444 * Shortcut the most recurring case: the user is in the dragging 445 * state and he is moving his finger. We want to intercept this 446 * motion. 447 */ 448 final int action = ev.getAction(); 449 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 450 return true; 451 } 452 453 switch (action & MotionEvent.ACTION_MASK) { 454 case MotionEvent.ACTION_MOVE: { 455 /* 456 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 457 * whether the user has moved far enough from his original down touch. 458 */ 459 460 /* 461 * Locally do absolute value. mLastMotionX is set to the x value 462 * of the down event. 463 */ 464 final int activePointerId = mActivePointerId; 465 if (activePointerId == INVALID_POINTER) { 466 // If we don't have a valid id, the touch down wasn't on content. 467 break; 468 } 469 470 final int pointerIndex = ev.findPointerIndex(activePointerId); 471 if (pointerIndex == -1) { 472 Log.e(TAG, "Invalid pointerId=" + activePointerId 473 + " in onInterceptTouchEvent"); 474 break; 475 } 476 477 final int x = (int) ev.getX(pointerIndex); 478 final int xDiff = (int) Math.abs(x - mLastMotionX); 479 if (xDiff > mTouchSlop) { 480 mIsBeingDragged = true; 481 mLastMotionX = x; 482 initVelocityTrackerIfNotExists(); 483 mVelocityTracker.addMovement(ev); 484 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 485 } 486 break; 487 } 488 489 case MotionEvent.ACTION_DOWN: { 490 final int x = (int) ev.getX(); 491 if (!inChild((int) x, (int) ev.getY())) { 492 mIsBeingDragged = false; 493 recycleVelocityTracker(); 494 break; 495 } 496 497 /* 498 * Remember location of down touch. 499 * ACTION_DOWN always refers to pointer index 0. 500 */ 501 mLastMotionX = x; 502 mActivePointerId = ev.getPointerId(0); 503 504 initOrResetVelocityTracker(); 505 mVelocityTracker.addMovement(ev); 506 507 /* 508 * If being flinged and user touches the screen, initiate drag; 509 * otherwise don't. mScroller.isFinished should be false when 510 * being flinged. 511 */ 512 mIsBeingDragged = !mScroller.isFinished(); 513 break; 514 } 515 516 case MotionEvent.ACTION_CANCEL: 517 case MotionEvent.ACTION_UP: 518 /* Release the drag */ 519 mIsBeingDragged = false; 520 mActivePointerId = INVALID_POINTER; 521 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 522 postInvalidateOnAnimation(); 523 } 524 break; 525 case MotionEvent.ACTION_POINTER_DOWN: { 526 final int index = ev.getActionIndex(); 527 mLastMotionX = (int) ev.getX(index); 528 mActivePointerId = ev.getPointerId(index); 529 break; 530 } 531 case MotionEvent.ACTION_POINTER_UP: 532 onSecondaryPointerUp(ev); 533 mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId)); 534 break; 535 } 536 537 /* 538 * The only time we want to intercept motion events is if we are in the 539 * drag mode. 540 */ 541 return mIsBeingDragged; 542 } 543 544 @Override 545 public boolean onTouchEvent(MotionEvent ev) { 546 initVelocityTrackerIfNotExists(); 547 mVelocityTracker.addMovement(ev); 548 549 final int action = ev.getAction(); 550 551 switch (action & MotionEvent.ACTION_MASK) { 552 case MotionEvent.ACTION_DOWN: { 553 if (getChildCount() == 0) { 554 return false; 555 } 556 if ((mIsBeingDragged = !mScroller.isFinished())) { 557 final ViewParent parent = getParent(); 558 if (parent != null) { 559 parent.requestDisallowInterceptTouchEvent(true); 560 } 561 } 562 563 /* 564 * If being flinged and user touches, stop the fling. isFinished 565 * will be false if being flinged. 566 */ 567 if (!mScroller.isFinished()) { 568 mScroller.abortAnimation(); 569 } 570 571 // Remember where the motion event started 572 mLastMotionX = (int) ev.getX(); 573 mActivePointerId = ev.getPointerId(0); 574 break; 575 } 576 case MotionEvent.ACTION_MOVE: 577 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 578 if (activePointerIndex == -1) { 579 Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); 580 break; 581 } 582 583 final int x = (int) ev.getX(activePointerIndex); 584 int deltaX = mLastMotionX - x; 585 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 586 final ViewParent parent = getParent(); 587 if (parent != null) { 588 parent.requestDisallowInterceptTouchEvent(true); 589 } 590 mIsBeingDragged = true; 591 if (deltaX > 0) { 592 deltaX -= mTouchSlop; 593 } else { 594 deltaX += mTouchSlop; 595 } 596 } 597 if (mIsBeingDragged) { 598 // Scroll to follow the motion event 599 mLastMotionX = x; 600 601 final int oldX = mScrollX; 602 final int oldY = mScrollY; 603 final int range = getScrollRange(); 604 final int overscrollMode = getOverScrollMode(); 605 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 606 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 607 608 // Calling overScrollBy will call onOverScrolled, which 609 // calls onScrollChanged if applicable. 610 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 611 mOverscrollDistance, 0, true)) { 612 // Break our velocity if we hit a scroll barrier. 613 mVelocityTracker.clear(); 614 } 615 616 if (canOverscroll) { 617 final int pulledToX = oldX + deltaX; 618 if (pulledToX < 0) { 619 mEdgeGlowLeft.onPull((float) deltaX / getWidth(), 620 1.f - ev.getY(activePointerIndex) / getHeight()); 621 if (!mEdgeGlowRight.isFinished()) { 622 mEdgeGlowRight.onRelease(); 623 } 624 } else if (pulledToX > range) { 625 mEdgeGlowRight.onPull((float) deltaX / getWidth(), 626 ev.getY(activePointerIndex) / getHeight()); 627 if (!mEdgeGlowLeft.isFinished()) { 628 mEdgeGlowLeft.onRelease(); 629 } 630 } 631 if (mEdgeGlowLeft != null 632 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 633 postInvalidateOnAnimation(); 634 } 635 } 636 } 637 break; 638 case MotionEvent.ACTION_UP: 639 if (mIsBeingDragged) { 640 final VelocityTracker velocityTracker = mVelocityTracker; 641 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 642 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 643 644 if (getChildCount() > 0) { 645 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 646 fling(-initialVelocity); 647 } else { 648 if (mScroller.springBack(mScrollX, mScrollY, 0, 649 getScrollRange(), 0, 0)) { 650 postInvalidateOnAnimation(); 651 } 652 } 653 } 654 655 mActivePointerId = INVALID_POINTER; 656 mIsBeingDragged = false; 657 recycleVelocityTracker(); 658 659 if (mEdgeGlowLeft != null) { 660 mEdgeGlowLeft.onRelease(); 661 mEdgeGlowRight.onRelease(); 662 } 663 } 664 break; 665 case MotionEvent.ACTION_CANCEL: 666 if (mIsBeingDragged && getChildCount() > 0) { 667 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 668 postInvalidateOnAnimation(); 669 } 670 mActivePointerId = INVALID_POINTER; 671 mIsBeingDragged = false; 672 recycleVelocityTracker(); 673 674 if (mEdgeGlowLeft != null) { 675 mEdgeGlowLeft.onRelease(); 676 mEdgeGlowRight.onRelease(); 677 } 678 } 679 break; 680 case MotionEvent.ACTION_POINTER_UP: 681 onSecondaryPointerUp(ev); 682 break; 683 } 684 return true; 685 } 686 687 private void onSecondaryPointerUp(MotionEvent ev) { 688 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 689 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 690 final int pointerId = ev.getPointerId(pointerIndex); 691 if (pointerId == mActivePointerId) { 692 // This was our active pointer going up. Choose a new 693 // active pointer and adjust accordingly. 694 // TODO: Make this decision more intelligent. 695 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 696 mLastMotionX = (int) ev.getX(newPointerIndex); 697 mActivePointerId = ev.getPointerId(newPointerIndex); 698 if (mVelocityTracker != null) { 699 mVelocityTracker.clear(); 700 } 701 } 702 } 703 704 @Override 705 public boolean onGenericMotionEvent(MotionEvent event) { 706 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 707 switch (event.getAction()) { 708 case MotionEvent.ACTION_SCROLL: { 709 if (!mIsBeingDragged) { 710 final float hscroll; 711 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 712 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 713 } else { 714 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 715 } 716 if (hscroll != 0) { 717 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 718 final int range = getScrollRange(); 719 int oldScrollX = mScrollX; 720 int newScrollX = oldScrollX + delta; 721 if (newScrollX < 0) { 722 newScrollX = 0; 723 } else if (newScrollX > range) { 724 newScrollX = range; 725 } 726 if (newScrollX != oldScrollX) { 727 super.scrollTo(newScrollX, mScrollY); 728 return true; 729 } 730 } 731 } 732 } 733 } 734 } 735 return super.onGenericMotionEvent(event); 736 } 737 738 @Override 739 public boolean shouldDelayChildPressedState() { 740 return true; 741 } 742 743 @Override 744 protected void onOverScrolled(int scrollX, int scrollY, 745 boolean clampedX, boolean clampedY) { 746 // Treat animating scrolls differently; see #computeScroll() for why. 747 if (!mScroller.isFinished()) { 748 final int oldX = mScrollX; 749 final int oldY = mScrollY; 750 mScrollX = scrollX; 751 mScrollY = scrollY; 752 invalidateParentIfNeeded(); 753 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 754 if (clampedX) { 755 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 756 } 757 } else { 758 super.scrollTo(scrollX, scrollY); 759 } 760 761 awakenScrollBars(); 762 } 763 764 /** @hide */ 765 @Override 766 public boolean performAccessibilityActionInternal(int action, Bundle arguments) { 767 if (super.performAccessibilityActionInternal(action, arguments)) { 768 return true; 769 } 770 switch (action) { 771 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 772 if (!isEnabled()) { 773 return false; 774 } 775 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 776 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 777 if (targetScrollX != mScrollX) { 778 smoothScrollTo(targetScrollX, 0); 779 return true; 780 } 781 } return false; 782 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 783 if (!isEnabled()) { 784 return false; 785 } 786 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 787 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 788 if (targetScrollX != mScrollX) { 789 smoothScrollTo(targetScrollX, 0); 790 return true; 791 } 792 } return false; 793 } 794 return false; 795 } 796 797 @Override 798 public CharSequence getAccessibilityClassName() { 799 return HorizontalScrollView.class.getName(); 800 } 801 802 /** @hide */ 803 @Override 804 public void onInitializeAccessibilityNodeInfoInternal(AccessibilityNodeInfo info) { 805 super.onInitializeAccessibilityNodeInfoInternal(info); 806 final int scrollRange = getScrollRange(); 807 if (scrollRange > 0) { 808 info.setScrollable(true); 809 if (isEnabled() && mScrollX > 0) { 810 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 811 } 812 if (isEnabled() && mScrollX < scrollRange) { 813 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 814 } 815 } 816 } 817 818 /** @hide */ 819 @Override 820 public void onInitializeAccessibilityEventInternal(AccessibilityEvent event) { 821 super.onInitializeAccessibilityEventInternal(event); 822 event.setScrollable(getScrollRange() > 0); 823 event.setScrollX(mScrollX); 824 event.setScrollY(mScrollY); 825 event.setMaxScrollX(getScrollRange()); 826 event.setMaxScrollY(mScrollY); 827 } 828 829 private int getScrollRange() { 830 int scrollRange = 0; 831 if (getChildCount() > 0) { 832 View child = getChildAt(0); 833 scrollRange = Math.max(0, 834 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 835 } 836 return scrollRange; 837 } 838 839 /** 840 * <p> 841 * Finds the next focusable component that fits in this View's bounds 842 * (excluding fading edges) pretending that this View's left is located at 843 * the parameter left. 844 * </p> 845 * 846 * @param leftFocus look for a candidate is the one at the left of the bounds 847 * if leftFocus is true, or at the right of the bounds if leftFocus 848 * is false 849 * @param left the left offset of the bounds in which a focusable must be 850 * found (the fading edge is assumed to start at this position) 851 * @param preferredFocusable the View that has highest priority and will be 852 * returned if it is within my bounds (null is valid) 853 * @return the next focusable component in the bounds or null if none can be found 854 */ 855 private View findFocusableViewInMyBounds(final boolean leftFocus, 856 final int left, View preferredFocusable) { 857 /* 858 * The fading edge's transparent side should be considered for focus 859 * since it's mostly visible, so we divide the actual fading edge length 860 * by 2. 861 */ 862 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 863 final int leftWithoutFadingEdge = left + fadingEdgeLength; 864 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 865 866 if ((preferredFocusable != null) 867 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 868 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 869 return preferredFocusable; 870 } 871 872 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 873 rightWithoutFadingEdge); 874 } 875 876 /** 877 * <p> 878 * Finds the next focusable component that fits in the specified bounds. 879 * </p> 880 * 881 * @param leftFocus look for a candidate is the one at the left of the bounds 882 * if leftFocus is true, or at the right of the bounds if 883 * leftFocus is false 884 * @param left the left offset of the bounds in which a focusable must be 885 * found 886 * @param right the right offset of the bounds in which a focusable must 887 * be found 888 * @return the next focusable component in the bounds or null if none can 889 * be found 890 */ 891 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 892 893 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 894 View focusCandidate = null; 895 896 /* 897 * A fully contained focusable is one where its left is below the bound's 898 * left, and its right is above the bound's right. A partially 899 * contained focusable is one where some part of it is within the 900 * bounds, but it also has some part that is not within bounds. A fully contained 901 * focusable is preferred to a partially contained focusable. 902 */ 903 boolean foundFullyContainedFocusable = false; 904 905 int count = focusables.size(); 906 for (int i = 0; i < count; i++) { 907 View view = focusables.get(i); 908 int viewLeft = view.getLeft(); 909 int viewRight = view.getRight(); 910 911 if (left < viewRight && viewLeft < right) { 912 /* 913 * the focusable is in the target area, it is a candidate for 914 * focusing 915 */ 916 917 final boolean viewIsFullyContained = (left < viewLeft) && 918 (viewRight < right); 919 920 if (focusCandidate == null) { 921 /* No candidate, take this one */ 922 focusCandidate = view; 923 foundFullyContainedFocusable = viewIsFullyContained; 924 } else { 925 final boolean viewIsCloserToBoundary = 926 (leftFocus && viewLeft < focusCandidate.getLeft()) || 927 (!leftFocus && viewRight > focusCandidate.getRight()); 928 929 if (foundFullyContainedFocusable) { 930 if (viewIsFullyContained && viewIsCloserToBoundary) { 931 /* 932 * We're dealing with only fully contained views, so 933 * it has to be closer to the boundary to beat our 934 * candidate 935 */ 936 focusCandidate = view; 937 } 938 } else { 939 if (viewIsFullyContained) { 940 /* Any fully contained view beats a partially contained view */ 941 focusCandidate = view; 942 foundFullyContainedFocusable = true; 943 } else if (viewIsCloserToBoundary) { 944 /* 945 * Partially contained view beats another partially 946 * contained view if it's closer 947 */ 948 focusCandidate = view; 949 } 950 } 951 } 952 } 953 } 954 955 return focusCandidate; 956 } 957 958 /** 959 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 960 * method will scroll the view by one page left or right and give the focus 961 * to the leftmost/rightmost component in the new visible area. If no 962 * component is a good candidate for focus, this scrollview reclaims the 963 * focus.</p> 964 * 965 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 966 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 967 * to go one page right 968 * @return true if the key event is consumed by this method, false otherwise 969 */ 970 public boolean pageScroll(int direction) { 971 boolean right = direction == View.FOCUS_RIGHT; 972 int width = getWidth(); 973 974 if (right) { 975 mTempRect.left = getScrollX() + width; 976 int count = getChildCount(); 977 if (count > 0) { 978 View view = getChildAt(0); 979 if (mTempRect.left + width > view.getRight()) { 980 mTempRect.left = view.getRight() - width; 981 } 982 } 983 } else { 984 mTempRect.left = getScrollX() - width; 985 if (mTempRect.left < 0) { 986 mTempRect.left = 0; 987 } 988 } 989 mTempRect.right = mTempRect.left + width; 990 991 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 992 } 993 994 /** 995 * <p>Handles scrolling in response to a "home/end" shortcut press. This 996 * method will scroll the view to the left or right and give the focus 997 * to the leftmost/rightmost component in the new visible area. If no 998 * component is a good candidate for focus, this scrollview reclaims the 999 * focus.</p> 1000 * 1001 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1002 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 1003 * to go the right 1004 * @return true if the key event is consumed by this method, false otherwise 1005 */ 1006 public boolean fullScroll(int direction) { 1007 boolean right = direction == View.FOCUS_RIGHT; 1008 int width = getWidth(); 1009 1010 mTempRect.left = 0; 1011 mTempRect.right = width; 1012 1013 if (right) { 1014 int count = getChildCount(); 1015 if (count > 0) { 1016 View view = getChildAt(0); 1017 mTempRect.right = view.getRight(); 1018 mTempRect.left = mTempRect.right - width; 1019 } 1020 } 1021 1022 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 1023 } 1024 1025 /** 1026 * <p>Scrolls the view to make the area defined by <code>left</code> and 1027 * <code>right</code> visible. This method attempts to give the focus 1028 * to a component visible in this area. If no component can be focused in 1029 * the new visible area, the focus is reclaimed by this scrollview.</p> 1030 * 1031 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1032 * to go left {@link android.view.View#FOCUS_RIGHT} to right 1033 * @param left the left offset of the new area to be made visible 1034 * @param right the right offset of the new area to be made visible 1035 * @return true if the key event is consumed by this method, false otherwise 1036 */ 1037 private boolean scrollAndFocus(int direction, int left, int right) { 1038 boolean handled = true; 1039 1040 int width = getWidth(); 1041 int containerLeft = getScrollX(); 1042 int containerRight = containerLeft + width; 1043 boolean goLeft = direction == View.FOCUS_LEFT; 1044 1045 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1046 if (newFocused == null) { 1047 newFocused = this; 1048 } 1049 1050 if (left >= containerLeft && right <= containerRight) { 1051 handled = false; 1052 } else { 1053 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1054 doScrollX(delta); 1055 } 1056 1057 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1058 1059 return handled; 1060 } 1061 1062 /** 1063 * Handle scrolling in response to a left or right arrow click. 1064 * 1065 * @param direction The direction corresponding to the arrow key that was 1066 * pressed 1067 * @return True if we consumed the event, false otherwise 1068 */ 1069 public boolean arrowScroll(int direction) { 1070 1071 View currentFocused = findFocus(); 1072 if (currentFocused == this) currentFocused = null; 1073 1074 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1075 1076 final int maxJump = getMaxScrollAmount(); 1077 1078 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1079 nextFocused.getDrawingRect(mTempRect); 1080 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1081 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1082 doScrollX(scrollDelta); 1083 nextFocused.requestFocus(direction); 1084 } else { 1085 // no new focus 1086 int scrollDelta = maxJump; 1087 1088 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1089 scrollDelta = getScrollX(); 1090 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1091 1092 int daRight = getChildAt(0).getRight(); 1093 1094 int screenRight = getScrollX() + getWidth(); 1095 1096 if (daRight - screenRight < maxJump) { 1097 scrollDelta = daRight - screenRight; 1098 } 1099 } 1100 if (scrollDelta == 0) { 1101 return false; 1102 } 1103 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1104 } 1105 1106 if (currentFocused != null && currentFocused.isFocused() 1107 && isOffScreen(currentFocused)) { 1108 // previously focused item still has focus and is off screen, give 1109 // it up (take it back to ourselves) 1110 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1111 // sure to 1112 // get it) 1113 final int descendantFocusability = getDescendantFocusability(); // save 1114 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1115 requestFocus(); 1116 setDescendantFocusability(descendantFocusability); // restore 1117 } 1118 return true; 1119 } 1120 1121 /** 1122 * @return whether the descendant of this scroll view is scrolled off 1123 * screen. 1124 */ 1125 private boolean isOffScreen(View descendant) { 1126 return !isWithinDeltaOfScreen(descendant, 0); 1127 } 1128 1129 /** 1130 * @return whether the descendant of this scroll view is within delta 1131 * pixels of being on the screen. 1132 */ 1133 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1134 descendant.getDrawingRect(mTempRect); 1135 offsetDescendantRectToMyCoords(descendant, mTempRect); 1136 1137 return (mTempRect.right + delta) >= getScrollX() 1138 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1139 } 1140 1141 /** 1142 * Smooth scroll by a X delta 1143 * 1144 * @param delta the number of pixels to scroll by on the X axis 1145 */ 1146 private void doScrollX(int delta) { 1147 if (delta != 0) { 1148 if (mSmoothScrollingEnabled) { 1149 smoothScrollBy(delta, 0); 1150 } else { 1151 scrollBy(delta, 0); 1152 } 1153 } 1154 } 1155 1156 /** 1157 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1158 * 1159 * @param dx the number of pixels to scroll by on the X axis 1160 * @param dy the number of pixels to scroll by on the Y axis 1161 */ 1162 public final void smoothScrollBy(int dx, int dy) { 1163 if (getChildCount() == 0) { 1164 // Nothing to do. 1165 return; 1166 } 1167 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1168 if (duration > ANIMATED_SCROLL_GAP) { 1169 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1170 final int right = getChildAt(0).getWidth(); 1171 final int maxX = Math.max(0, right - width); 1172 final int scrollX = mScrollX; 1173 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1174 1175 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1176 postInvalidateOnAnimation(); 1177 } else { 1178 if (!mScroller.isFinished()) { 1179 mScroller.abortAnimation(); 1180 } 1181 scrollBy(dx, dy); 1182 } 1183 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1184 } 1185 1186 /** 1187 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1188 * 1189 * @param x the position where to scroll on the X axis 1190 * @param y the position where to scroll on the Y axis 1191 */ 1192 public final void smoothScrollTo(int x, int y) { 1193 smoothScrollBy(x - mScrollX, y - mScrollY); 1194 } 1195 1196 /** 1197 * <p>The scroll range of a scroll view is the overall width of all of its 1198 * children.</p> 1199 */ 1200 @Override 1201 protected int computeHorizontalScrollRange() { 1202 final int count = getChildCount(); 1203 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1204 if (count == 0) { 1205 return contentWidth; 1206 } 1207 1208 int scrollRange = getChildAt(0).getRight(); 1209 final int scrollX = mScrollX; 1210 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1211 if (scrollX < 0) { 1212 scrollRange -= scrollX; 1213 } else if (scrollX > overscrollRight) { 1214 scrollRange += scrollX - overscrollRight; 1215 } 1216 1217 return scrollRange; 1218 } 1219 1220 @Override 1221 protected int computeHorizontalScrollOffset() { 1222 return Math.max(0, super.computeHorizontalScrollOffset()); 1223 } 1224 1225 @Override 1226 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1227 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1228 1229 int childWidthMeasureSpec; 1230 int childHeightMeasureSpec; 1231 1232 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1233 + mPaddingBottom, lp.height); 1234 1235 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1236 1237 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1238 } 1239 1240 @Override 1241 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1242 int parentHeightMeasureSpec, int heightUsed) { 1243 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1244 1245 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1246 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1247 + heightUsed, lp.height); 1248 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1249 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1250 1251 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1252 } 1253 1254 @Override 1255 public void computeScroll() { 1256 if (mScroller.computeScrollOffset()) { 1257 // This is called at drawing time by ViewGroup. We don't want to 1258 // re-show the scrollbars at this point, which scrollTo will do, 1259 // so we replicate most of scrollTo here. 1260 // 1261 // It's a little odd to call onScrollChanged from inside the drawing. 1262 // 1263 // It is, except when you remember that computeScroll() is used to 1264 // animate scrolling. So unless we want to defer the onScrollChanged() 1265 // until the end of the animated scrolling, we don't really have a 1266 // choice here. 1267 // 1268 // I agree. The alternative, which I think would be worse, is to post 1269 // something and tell the subclasses later. This is bad because there 1270 // will be a window where mScrollX/Y is different from what the app 1271 // thinks it is. 1272 // 1273 int oldX = mScrollX; 1274 int oldY = mScrollY; 1275 int x = mScroller.getCurrX(); 1276 int y = mScroller.getCurrY(); 1277 1278 if (oldX != x || oldY != y) { 1279 final int range = getScrollRange(); 1280 final int overscrollMode = getOverScrollMode(); 1281 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1282 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1283 1284 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1285 mOverflingDistance, 0, false); 1286 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1287 1288 if (canOverscroll) { 1289 if (x < 0 && oldX >= 0) { 1290 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1291 } else if (x > range && oldX <= range) { 1292 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1293 } 1294 } 1295 } 1296 1297 if (!awakenScrollBars()) { 1298 postInvalidateOnAnimation(); 1299 } 1300 } 1301 } 1302 1303 /** 1304 * Scrolls the view to the given child. 1305 * 1306 * @param child the View to scroll to 1307 */ 1308 private void scrollToChild(View child) { 1309 child.getDrawingRect(mTempRect); 1310 1311 /* Offset from child's local coordinates to ScrollView coordinates */ 1312 offsetDescendantRectToMyCoords(child, mTempRect); 1313 1314 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1315 1316 if (scrollDelta != 0) { 1317 scrollBy(scrollDelta, 0); 1318 } 1319 } 1320 1321 /** 1322 * If rect is off screen, scroll just enough to get it (or at least the 1323 * first screen size chunk of it) on screen. 1324 * 1325 * @param rect The rectangle. 1326 * @param immediate True to scroll immediately without animation 1327 * @return true if scrolling was performed 1328 */ 1329 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1330 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1331 final boolean scroll = delta != 0; 1332 if (scroll) { 1333 if (immediate) { 1334 scrollBy(delta, 0); 1335 } else { 1336 smoothScrollBy(delta, 0); 1337 } 1338 } 1339 return scroll; 1340 } 1341 1342 /** 1343 * Compute the amount to scroll in the X direction in order to get 1344 * a rectangle completely on the screen (or, if taller than the screen, 1345 * at least the first screen size chunk of it). 1346 * 1347 * @param rect The rect. 1348 * @return The scroll delta. 1349 */ 1350 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1351 if (getChildCount() == 0) return 0; 1352 1353 int width = getWidth(); 1354 int screenLeft = getScrollX(); 1355 int screenRight = screenLeft + width; 1356 1357 int fadingEdge = getHorizontalFadingEdgeLength(); 1358 1359 // leave room for left fading edge as long as rect isn't at very left 1360 if (rect.left > 0) { 1361 screenLeft += fadingEdge; 1362 } 1363 1364 // leave room for right fading edge as long as rect isn't at very right 1365 if (rect.right < getChildAt(0).getWidth()) { 1366 screenRight -= fadingEdge; 1367 } 1368 1369 int scrollXDelta = 0; 1370 1371 if (rect.right > screenRight && rect.left > screenLeft) { 1372 // need to move right to get it in view: move right just enough so 1373 // that the entire rectangle is in view (or at least the first 1374 // screen size chunk). 1375 1376 if (rect.width() > width) { 1377 // just enough to get screen size chunk on 1378 scrollXDelta += (rect.left - screenLeft); 1379 } else { 1380 // get entire rect at right of screen 1381 scrollXDelta += (rect.right - screenRight); 1382 } 1383 1384 // make sure we aren't scrolling beyond the end of our content 1385 int right = getChildAt(0).getRight(); 1386 int distanceToRight = right - screenRight; 1387 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1388 1389 } else if (rect.left < screenLeft && rect.right < screenRight) { 1390 // need to move right to get it in view: move right just enough so that 1391 // entire rectangle is in view (or at least the first screen 1392 // size chunk of it). 1393 1394 if (rect.width() > width) { 1395 // screen size chunk 1396 scrollXDelta -= (screenRight - rect.right); 1397 } else { 1398 // entire rect at left 1399 scrollXDelta -= (screenLeft - rect.left); 1400 } 1401 1402 // make sure we aren't scrolling any further than the left our content 1403 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1404 } 1405 return scrollXDelta; 1406 } 1407 1408 @Override 1409 public void requestChildFocus(View child, View focused) { 1410 if (!mIsLayoutDirty) { 1411 scrollToChild(focused); 1412 } else { 1413 // The child may not be laid out yet, we can't compute the scroll yet 1414 mChildToScrollTo = focused; 1415 } 1416 super.requestChildFocus(child, focused); 1417 } 1418 1419 1420 /** 1421 * When looking for focus in children of a scroll view, need to be a little 1422 * more careful not to give focus to something that is scrolled off screen. 1423 * 1424 * This is more expensive than the default {@link android.view.ViewGroup} 1425 * implementation, otherwise this behavior might have been made the default. 1426 */ 1427 @Override 1428 protected boolean onRequestFocusInDescendants(int direction, 1429 Rect previouslyFocusedRect) { 1430 1431 // convert from forward / backward notation to up / down / left / right 1432 // (ugh). 1433 if (direction == View.FOCUS_FORWARD) { 1434 direction = View.FOCUS_RIGHT; 1435 } else if (direction == View.FOCUS_BACKWARD) { 1436 direction = View.FOCUS_LEFT; 1437 } 1438 1439 final View nextFocus = previouslyFocusedRect == null ? 1440 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1441 FocusFinder.getInstance().findNextFocusFromRect(this, 1442 previouslyFocusedRect, direction); 1443 1444 if (nextFocus == null) { 1445 return false; 1446 } 1447 1448 if (isOffScreen(nextFocus)) { 1449 return false; 1450 } 1451 1452 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1453 } 1454 1455 @Override 1456 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1457 boolean immediate) { 1458 // offset into coordinate space of this scroll view 1459 rectangle.offset(child.getLeft() - child.getScrollX(), 1460 child.getTop() - child.getScrollY()); 1461 1462 return scrollToChildRect(rectangle, immediate); 1463 } 1464 1465 @Override 1466 public void requestLayout() { 1467 mIsLayoutDirty = true; 1468 super.requestLayout(); 1469 } 1470 1471 @Override 1472 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1473 int childWidth = 0; 1474 int childMargins = 0; 1475 1476 if (getChildCount() > 0) { 1477 childWidth = getChildAt(0).getMeasuredWidth(); 1478 LayoutParams childParams = (LayoutParams) getChildAt(0).getLayoutParams(); 1479 childMargins = childParams.leftMargin + childParams.rightMargin; 1480 } 1481 1482 final int available = r - l - getPaddingLeftWithForeground() - 1483 getPaddingRightWithForeground() - childMargins; 1484 1485 final boolean forceLeftGravity = (childWidth > available); 1486 1487 layoutChildren(l, t, r, b, forceLeftGravity); 1488 1489 mIsLayoutDirty = false; 1490 // Give a child focus if it needs it 1491 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1492 scrollToChild(mChildToScrollTo); 1493 } 1494 mChildToScrollTo = null; 1495 1496 if (!isLaidOut()) { 1497 final int scrollRange = Math.max(0, 1498 childWidth - (r - l - mPaddingLeft - mPaddingRight)); 1499 if (mSavedState != null) { 1500 if (isLayoutRtl() == mSavedState.isLayoutRtl) { 1501 mScrollX = mSavedState.scrollPosition; 1502 } else { 1503 mScrollX = scrollRange - mSavedState.scrollPosition; 1504 } 1505 mSavedState = null; 1506 } else { 1507 if (isLayoutRtl()) { 1508 mScrollX = scrollRange - mScrollX; 1509 } // mScrollX default value is "0" for LTR 1510 } 1511 // Don't forget to clamp 1512 if (mScrollX > scrollRange) { 1513 mScrollX = scrollRange; 1514 } else if (mScrollX < 0) { 1515 mScrollX = 0; 1516 } 1517 } 1518 1519 // Calling this with the present values causes it to re-claim them 1520 scrollTo(mScrollX, mScrollY); 1521 } 1522 1523 @Override 1524 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1525 super.onSizeChanged(w, h, oldw, oldh); 1526 1527 View currentFocused = findFocus(); 1528 if (null == currentFocused || this == currentFocused) 1529 return; 1530 1531 final int maxJump = mRight - mLeft; 1532 1533 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1534 currentFocused.getDrawingRect(mTempRect); 1535 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1536 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1537 doScrollX(scrollDelta); 1538 } 1539 } 1540 1541 /** 1542 * Return true if child is a descendant of parent, (or equal to the parent). 1543 */ 1544 private static boolean isViewDescendantOf(View child, View parent) { 1545 if (child == parent) { 1546 return true; 1547 } 1548 1549 final ViewParent theParent = child.getParent(); 1550 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1551 } 1552 1553 /** 1554 * Fling the scroll view 1555 * 1556 * @param velocityX The initial velocity in the X direction. Positive 1557 * numbers mean that the finger/cursor is moving down the screen, 1558 * which means we want to scroll towards the left. 1559 */ 1560 public void fling(int velocityX) { 1561 if (getChildCount() > 0) { 1562 int width = getWidth() - mPaddingRight - mPaddingLeft; 1563 int right = getChildAt(0).getWidth(); 1564 1565 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1566 Math.max(0, right - width), 0, 0, width/2, 0); 1567 1568 final boolean movingRight = velocityX > 0; 1569 1570 View currentFocused = findFocus(); 1571 View newFocused = findFocusableViewInMyBounds(movingRight, 1572 mScroller.getFinalX(), currentFocused); 1573 1574 if (newFocused == null) { 1575 newFocused = this; 1576 } 1577 1578 if (newFocused != currentFocused) { 1579 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1580 } 1581 1582 postInvalidateOnAnimation(); 1583 } 1584 } 1585 1586 /** 1587 * {@inheritDoc} 1588 * 1589 * <p>This version also clamps the scrolling to the bounds of our child. 1590 */ 1591 @Override 1592 public void scrollTo(int x, int y) { 1593 // we rely on the fact the View.scrollBy calls scrollTo. 1594 if (getChildCount() > 0) { 1595 View child = getChildAt(0); 1596 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1597 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1598 if (x != mScrollX || y != mScrollY) { 1599 super.scrollTo(x, y); 1600 } 1601 } 1602 } 1603 1604 @Override 1605 public void setOverScrollMode(int mode) { 1606 if (mode != OVER_SCROLL_NEVER) { 1607 if (mEdgeGlowLeft == null) { 1608 Context context = getContext(); 1609 mEdgeGlowLeft = new EdgeEffect(context); 1610 mEdgeGlowRight = new EdgeEffect(context); 1611 } 1612 } else { 1613 mEdgeGlowLeft = null; 1614 mEdgeGlowRight = null; 1615 } 1616 super.setOverScrollMode(mode); 1617 } 1618 1619 @SuppressWarnings({"SuspiciousNameCombination"}) 1620 @Override 1621 public void draw(Canvas canvas) { 1622 super.draw(canvas); 1623 if (mEdgeGlowLeft != null) { 1624 final int scrollX = mScrollX; 1625 if (!mEdgeGlowLeft.isFinished()) { 1626 final int restoreCount = canvas.save(); 1627 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1628 1629 canvas.rotate(270); 1630 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1631 mEdgeGlowLeft.setSize(height, getWidth()); 1632 if (mEdgeGlowLeft.draw(canvas)) { 1633 postInvalidateOnAnimation(); 1634 } 1635 canvas.restoreToCount(restoreCount); 1636 } 1637 if (!mEdgeGlowRight.isFinished()) { 1638 final int restoreCount = canvas.save(); 1639 final int width = getWidth(); 1640 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1641 1642 canvas.rotate(90); 1643 canvas.translate(-mPaddingTop, 1644 -(Math.max(getScrollRange(), scrollX) + width)); 1645 mEdgeGlowRight.setSize(height, width); 1646 if (mEdgeGlowRight.draw(canvas)) { 1647 postInvalidateOnAnimation(); 1648 } 1649 canvas.restoreToCount(restoreCount); 1650 } 1651 } 1652 } 1653 1654 private static int clamp(int n, int my, int child) { 1655 if (my >= child || n < 0) { 1656 return 0; 1657 } 1658 if ((my + n) > child) { 1659 return child - my; 1660 } 1661 return n; 1662 } 1663 1664 @Override 1665 protected void onRestoreInstanceState(Parcelable state) { 1666 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1667 // Some old apps reused IDs in ways they shouldn't have. 1668 // Don't break them, but they don't get scroll state restoration. 1669 super.onRestoreInstanceState(state); 1670 return; 1671 } 1672 SavedState ss = (SavedState) state; 1673 super.onRestoreInstanceState(ss.getSuperState()); 1674 mSavedState = ss; 1675 requestLayout(); 1676 } 1677 1678 @Override 1679 protected Parcelable onSaveInstanceState() { 1680 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1681 // Some old apps reused IDs in ways they shouldn't have. 1682 // Don't break them, but they don't get scroll state restoration. 1683 return super.onSaveInstanceState(); 1684 } 1685 Parcelable superState = super.onSaveInstanceState(); 1686 SavedState ss = new SavedState(superState); 1687 ss.scrollPosition = mScrollX; 1688 ss.isLayoutRtl = isLayoutRtl(); 1689 return ss; 1690 } 1691 1692 static class SavedState extends BaseSavedState { 1693 public int scrollPosition; 1694 public boolean isLayoutRtl; 1695 1696 SavedState(Parcelable superState) { 1697 super(superState); 1698 } 1699 1700 public SavedState(Parcel source) { 1701 super(source); 1702 scrollPosition = source.readInt(); 1703 isLayoutRtl = (source.readInt() == 0) ? true : false; 1704 } 1705 1706 @Override 1707 public void writeToParcel(Parcel dest, int flags) { 1708 super.writeToParcel(dest, flags); 1709 dest.writeInt(scrollPosition); 1710 dest.writeInt(isLayoutRtl ? 1 : 0); 1711 } 1712 1713 @Override 1714 public String toString() { 1715 return "HorizontalScrollView.SavedState{" 1716 + Integer.toHexString(System.identityHashCode(this)) 1717 + " scrollPosition=" + scrollPosition 1718 + " isLayoutRtl=" + isLayoutRtl + "}"; 1719 } 1720 1721 public static final Parcelable.Creator<SavedState> CREATOR 1722 = new Parcelable.Creator<SavedState>() { 1723 public SavedState createFromParcel(Parcel in) { 1724 return new SavedState(in); 1725 } 1726 1727 public SavedState[] newArray(int size) { 1728 return new SavedState[size]; 1729 } 1730 }; 1731 } 1732} 1733