1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.widget; 18 19 import android.content.Context; 20 import android.content.res.TypedArray; 21 import android.graphics.Canvas; 22 import android.graphics.Rect; 23 import android.graphics.RectF; 24 import android.os.Build; 25 import android.os.Bundle; 26 import android.os.Parcel; 27 import android.os.Parcelable; 28 import android.util.AttributeSet; 29 import android.util.Log; 30 import android.view.FocusFinder; 31 import android.view.InputDevice; 32 import android.view.KeyEvent; 33 import android.view.MotionEvent; 34 import android.view.VelocityTracker; 35 import android.view.View; 36 import android.view.ViewConfiguration; 37 import android.view.ViewDebug; 38 import android.view.ViewGroup; 39 import android.view.ViewParent; 40 import android.view.accessibility.AccessibilityEvent; 41 import android.view.accessibility.AccessibilityNodeInfo; 42 import android.view.animation.AnimationUtils; 43 44 import 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 */ 65 public 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 @Override 766 public boolean performAccessibilityAction(int action, Bundle arguments) { 767 if (super.performAccessibilityAction(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 void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 799 super.onInitializeAccessibilityNodeInfo(info); 800 info.setClassName(HorizontalScrollView.class.getName()); 801 final int scrollRange = getScrollRange(); 802 if (scrollRange > 0) { 803 info.setScrollable(true); 804 if (isEnabled() && mScrollX > 0) { 805 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 806 } 807 if (isEnabled() && mScrollX < scrollRange) { 808 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 809 } 810 } 811 } 812 813 @Override 814 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 815 super.onInitializeAccessibilityEvent(event); 816 event.setClassName(HorizontalScrollView.class.getName()); 817 event.setScrollable(getScrollRange() > 0); 818 event.setScrollX(mScrollX); 819 event.setScrollY(mScrollY); 820 event.setMaxScrollX(getScrollRange()); 821 event.setMaxScrollY(mScrollY); 822 } 823 824 private int getScrollRange() { 825 int scrollRange = 0; 826 if (getChildCount() > 0) { 827 View child = getChildAt(0); 828 scrollRange = Math.max(0, 829 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 830 } 831 return scrollRange; 832 } 833 834 /** 835 * <p> 836 * Finds the next focusable component that fits in this View's bounds 837 * (excluding fading edges) pretending that this View's left is located at 838 * the parameter left. 839 * </p> 840 * 841 * @param leftFocus look for a candidate is the one at the left of the bounds 842 * if leftFocus is true, or at the right of the bounds if leftFocus 843 * is false 844 * @param left the left offset of the bounds in which a focusable must be 845 * found (the fading edge is assumed to start at this position) 846 * @param preferredFocusable the View that has highest priority and will be 847 * returned if it is within my bounds (null is valid) 848 * @return the next focusable component in the bounds or null if none can be found 849 */ 850 private View findFocusableViewInMyBounds(final boolean leftFocus, 851 final int left, View preferredFocusable) { 852 /* 853 * The fading edge's transparent side should be considered for focus 854 * since it's mostly visible, so we divide the actual fading edge length 855 * by 2. 856 */ 857 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 858 final int leftWithoutFadingEdge = left + fadingEdgeLength; 859 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 860 861 if ((preferredFocusable != null) 862 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 863 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 864 return preferredFocusable; 865 } 866 867 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 868 rightWithoutFadingEdge); 869 } 870 871 /** 872 * <p> 873 * Finds the next focusable component that fits in the specified bounds. 874 * </p> 875 * 876 * @param leftFocus look for a candidate is the one at the left of the bounds 877 * if leftFocus is true, or at the right of the bounds if 878 * leftFocus is false 879 * @param left the left offset of the bounds in which a focusable must be 880 * found 881 * @param right the right offset of the bounds in which a focusable must 882 * be found 883 * @return the next focusable component in the bounds or null if none can 884 * be found 885 */ 886 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 887 888 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 889 View focusCandidate = null; 890 891 /* 892 * A fully contained focusable is one where its left is below the bound's 893 * left, and its right is above the bound's right. A partially 894 * contained focusable is one where some part of it is within the 895 * bounds, but it also has some part that is not within bounds. A fully contained 896 * focusable is preferred to a partially contained focusable. 897 */ 898 boolean foundFullyContainedFocusable = false; 899 900 int count = focusables.size(); 901 for (int i = 0; i < count; i++) { 902 View view = focusables.get(i); 903 int viewLeft = view.getLeft(); 904 int viewRight = view.getRight(); 905 906 if (left < viewRight && viewLeft < right) { 907 /* 908 * the focusable is in the target area, it is a candidate for 909 * focusing 910 */ 911 912 final boolean viewIsFullyContained = (left < viewLeft) && 913 (viewRight < right); 914 915 if (focusCandidate == null) { 916 /* No candidate, take this one */ 917 focusCandidate = view; 918 foundFullyContainedFocusable = viewIsFullyContained; 919 } else { 920 final boolean viewIsCloserToBoundary = 921 (leftFocus && viewLeft < focusCandidate.getLeft()) || 922 (!leftFocus && viewRight > focusCandidate.getRight()); 923 924 if (foundFullyContainedFocusable) { 925 if (viewIsFullyContained && viewIsCloserToBoundary) { 926 /* 927 * We're dealing with only fully contained views, so 928 * it has to be closer to the boundary to beat our 929 * candidate 930 */ 931 focusCandidate = view; 932 } 933 } else { 934 if (viewIsFullyContained) { 935 /* Any fully contained view beats a partially contained view */ 936 focusCandidate = view; 937 foundFullyContainedFocusable = true; 938 } else if (viewIsCloserToBoundary) { 939 /* 940 * Partially contained view beats another partially 941 * contained view if it's closer 942 */ 943 focusCandidate = view; 944 } 945 } 946 } 947 } 948 } 949 950 return focusCandidate; 951 } 952 953 /** 954 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 955 * method will scroll the view by one page left or right and give the focus 956 * to the leftmost/rightmost component in the new visible area. If no 957 * component is a good candidate for focus, this scrollview reclaims the 958 * focus.</p> 959 * 960 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 961 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 962 * to go one page right 963 * @return true if the key event is consumed by this method, false otherwise 964 */ 965 public boolean pageScroll(int direction) { 966 boolean right = direction == View.FOCUS_RIGHT; 967 int width = getWidth(); 968 969 if (right) { 970 mTempRect.left = getScrollX() + width; 971 int count = getChildCount(); 972 if (count > 0) { 973 View view = getChildAt(0); 974 if (mTempRect.left + width > view.getRight()) { 975 mTempRect.left = view.getRight() - width; 976 } 977 } 978 } else { 979 mTempRect.left = getScrollX() - width; 980 if (mTempRect.left < 0) { 981 mTempRect.left = 0; 982 } 983 } 984 mTempRect.right = mTempRect.left + width; 985 986 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 987 } 988 989 /** 990 * <p>Handles scrolling in response to a "home/end" shortcut press. This 991 * method will scroll the view to the left or right and give the focus 992 * to the leftmost/rightmost component in the new visible area. If no 993 * component is a good candidate for focus, this scrollview reclaims the 994 * focus.</p> 995 * 996 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 997 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 998 * to go the right 999 * @return true if the key event is consumed by this method, false otherwise 1000 */ 1001 public boolean fullScroll(int direction) { 1002 boolean right = direction == View.FOCUS_RIGHT; 1003 int width = getWidth(); 1004 1005 mTempRect.left = 0; 1006 mTempRect.right = width; 1007 1008 if (right) { 1009 int count = getChildCount(); 1010 if (count > 0) { 1011 View view = getChildAt(0); 1012 mTempRect.right = view.getRight(); 1013 mTempRect.left = mTempRect.right - width; 1014 } 1015 } 1016 1017 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 1018 } 1019 1020 /** 1021 * <p>Scrolls the view to make the area defined by <code>left</code> and 1022 * <code>right</code> visible. This method attempts to give the focus 1023 * to a component visible in this area. If no component can be focused in 1024 * the new visible area, the focus is reclaimed by this scrollview.</p> 1025 * 1026 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1027 * to go left {@link android.view.View#FOCUS_RIGHT} to right 1028 * @param left the left offset of the new area to be made visible 1029 * @param right the right offset of the new area to be made visible 1030 * @return true if the key event is consumed by this method, false otherwise 1031 */ 1032 private boolean scrollAndFocus(int direction, int left, int right) { 1033 boolean handled = true; 1034 1035 int width = getWidth(); 1036 int containerLeft = getScrollX(); 1037 int containerRight = containerLeft + width; 1038 boolean goLeft = direction == View.FOCUS_LEFT; 1039 1040 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1041 if (newFocused == null) { 1042 newFocused = this; 1043 } 1044 1045 if (left >= containerLeft && right <= containerRight) { 1046 handled = false; 1047 } else { 1048 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1049 doScrollX(delta); 1050 } 1051 1052 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1053 1054 return handled; 1055 } 1056 1057 /** 1058 * Handle scrolling in response to a left or right arrow click. 1059 * 1060 * @param direction The direction corresponding to the arrow key that was 1061 * pressed 1062 * @return True if we consumed the event, false otherwise 1063 */ 1064 public boolean arrowScroll(int direction) { 1065 1066 View currentFocused = findFocus(); 1067 if (currentFocused == this) currentFocused = null; 1068 1069 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1070 1071 final int maxJump = getMaxScrollAmount(); 1072 1073 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1074 nextFocused.getDrawingRect(mTempRect); 1075 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1076 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1077 doScrollX(scrollDelta); 1078 nextFocused.requestFocus(direction); 1079 } else { 1080 // no new focus 1081 int scrollDelta = maxJump; 1082 1083 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1084 scrollDelta = getScrollX(); 1085 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1086 1087 int daRight = getChildAt(0).getRight(); 1088 1089 int screenRight = getScrollX() + getWidth(); 1090 1091 if (daRight - screenRight < maxJump) { 1092 scrollDelta = daRight - screenRight; 1093 } 1094 } 1095 if (scrollDelta == 0) { 1096 return false; 1097 } 1098 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1099 } 1100 1101 if (currentFocused != null && currentFocused.isFocused() 1102 && isOffScreen(currentFocused)) { 1103 // previously focused item still has focus and is off screen, give 1104 // it up (take it back to ourselves) 1105 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1106 // sure to 1107 // get it) 1108 final int descendantFocusability = getDescendantFocusability(); // save 1109 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1110 requestFocus(); 1111 setDescendantFocusability(descendantFocusability); // restore 1112 } 1113 return true; 1114 } 1115 1116 /** 1117 * @return whether the descendant of this scroll view is scrolled off 1118 * screen. 1119 */ 1120 private boolean isOffScreen(View descendant) { 1121 return !isWithinDeltaOfScreen(descendant, 0); 1122 } 1123 1124 /** 1125 * @return whether the descendant of this scroll view is within delta 1126 * pixels of being on the screen. 1127 */ 1128 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1129 descendant.getDrawingRect(mTempRect); 1130 offsetDescendantRectToMyCoords(descendant, mTempRect); 1131 1132 return (mTempRect.right + delta) >= getScrollX() 1133 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1134 } 1135 1136 /** 1137 * Smooth scroll by a X delta 1138 * 1139 * @param delta the number of pixels to scroll by on the X axis 1140 */ 1141 private void doScrollX(int delta) { 1142 if (delta != 0) { 1143 if (mSmoothScrollingEnabled) { 1144 smoothScrollBy(delta, 0); 1145 } else { 1146 scrollBy(delta, 0); 1147 } 1148 } 1149 } 1150 1151 /** 1152 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1153 * 1154 * @param dx the number of pixels to scroll by on the X axis 1155 * @param dy the number of pixels to scroll by on the Y axis 1156 */ 1157 public final void smoothScrollBy(int dx, int dy) { 1158 if (getChildCount() == 0) { 1159 // Nothing to do. 1160 return; 1161 } 1162 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1163 if (duration > ANIMATED_SCROLL_GAP) { 1164 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1165 final int right = getChildAt(0).getWidth(); 1166 final int maxX = Math.max(0, right - width); 1167 final int scrollX = mScrollX; 1168 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1169 1170 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1171 postInvalidateOnAnimation(); 1172 } else { 1173 if (!mScroller.isFinished()) { 1174 mScroller.abortAnimation(); 1175 } 1176 scrollBy(dx, dy); 1177 } 1178 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1179 } 1180 1181 /** 1182 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1183 * 1184 * @param x the position where to scroll on the X axis 1185 * @param y the position where to scroll on the Y axis 1186 */ 1187 public final void smoothScrollTo(int x, int y) { 1188 smoothScrollBy(x - mScrollX, y - mScrollY); 1189 } 1190 1191 /** 1192 * <p>The scroll range of a scroll view is the overall width of all of its 1193 * children.</p> 1194 */ 1195 @Override 1196 protected int computeHorizontalScrollRange() { 1197 final int count = getChildCount(); 1198 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1199 if (count == 0) { 1200 return contentWidth; 1201 } 1202 1203 int scrollRange = getChildAt(0).getRight(); 1204 final int scrollX = mScrollX; 1205 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1206 if (scrollX < 0) { 1207 scrollRange -= scrollX; 1208 } else if (scrollX > overscrollRight) { 1209 scrollRange += scrollX - overscrollRight; 1210 } 1211 1212 return scrollRange; 1213 } 1214 1215 @Override 1216 protected int computeHorizontalScrollOffset() { 1217 return Math.max(0, super.computeHorizontalScrollOffset()); 1218 } 1219 1220 @Override 1221 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1222 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1223 1224 int childWidthMeasureSpec; 1225 int childHeightMeasureSpec; 1226 1227 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1228 + mPaddingBottom, lp.height); 1229 1230 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1231 1232 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1233 } 1234 1235 @Override 1236 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1237 int parentHeightMeasureSpec, int heightUsed) { 1238 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1239 1240 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1241 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1242 + heightUsed, lp.height); 1243 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1244 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1245 1246 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1247 } 1248 1249 @Override 1250 public void computeScroll() { 1251 if (mScroller.computeScrollOffset()) { 1252 // This is called at drawing time by ViewGroup. We don't want to 1253 // re-show the scrollbars at this point, which scrollTo will do, 1254 // so we replicate most of scrollTo here. 1255 // 1256 // It's a little odd to call onScrollChanged from inside the drawing. 1257 // 1258 // It is, except when you remember that computeScroll() is used to 1259 // animate scrolling. So unless we want to defer the onScrollChanged() 1260 // until the end of the animated scrolling, we don't really have a 1261 // choice here. 1262 // 1263 // I agree. The alternative, which I think would be worse, is to post 1264 // something and tell the subclasses later. This is bad because there 1265 // will be a window where mScrollX/Y is different from what the app 1266 // thinks it is. 1267 // 1268 int oldX = mScrollX; 1269 int oldY = mScrollY; 1270 int x = mScroller.getCurrX(); 1271 int y = mScroller.getCurrY(); 1272 1273 if (oldX != x || oldY != y) { 1274 final int range = getScrollRange(); 1275 final int overscrollMode = getOverScrollMode(); 1276 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1277 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1278 1279 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1280 mOverflingDistance, 0, false); 1281 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1282 1283 if (canOverscroll) { 1284 if (x < 0 && oldX >= 0) { 1285 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1286 } else if (x > range && oldX <= range) { 1287 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1288 } 1289 } 1290 } 1291 1292 if (!awakenScrollBars()) { 1293 postInvalidateOnAnimation(); 1294 } 1295 } 1296 } 1297 1298 /** 1299 * Scrolls the view to the given child. 1300 * 1301 * @param child the View to scroll to 1302 */ 1303 private void scrollToChild(View child) { 1304 child.getDrawingRect(mTempRect); 1305 1306 /* Offset from child's local coordinates to ScrollView coordinates */ 1307 offsetDescendantRectToMyCoords(child, mTempRect); 1308 1309 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1310 1311 if (scrollDelta != 0) { 1312 scrollBy(scrollDelta, 0); 1313 } 1314 } 1315 1316 /** 1317 * If rect is off screen, scroll just enough to get it (or at least the 1318 * first screen size chunk of it) on screen. 1319 * 1320 * @param rect The rectangle. 1321 * @param immediate True to scroll immediately without animation 1322 * @return true if scrolling was performed 1323 */ 1324 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1325 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1326 final boolean scroll = delta != 0; 1327 if (scroll) { 1328 if (immediate) { 1329 scrollBy(delta, 0); 1330 } else { 1331 smoothScrollBy(delta, 0); 1332 } 1333 } 1334 return scroll; 1335 } 1336 1337 /** 1338 * Compute the amount to scroll in the X direction in order to get 1339 * a rectangle completely on the screen (or, if taller than the screen, 1340 * at least the first screen size chunk of it). 1341 * 1342 * @param rect The rect. 1343 * @return The scroll delta. 1344 */ 1345 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1346 if (getChildCount() == 0) return 0; 1347 1348 int width = getWidth(); 1349 int screenLeft = getScrollX(); 1350 int screenRight = screenLeft + width; 1351 1352 int fadingEdge = getHorizontalFadingEdgeLength(); 1353 1354 // leave room for left fading edge as long as rect isn't at very left 1355 if (rect.left > 0) { 1356 screenLeft += fadingEdge; 1357 } 1358 1359 // leave room for right fading edge as long as rect isn't at very right 1360 if (rect.right < getChildAt(0).getWidth()) { 1361 screenRight -= fadingEdge; 1362 } 1363 1364 int scrollXDelta = 0; 1365 1366 if (rect.right > screenRight && rect.left > screenLeft) { 1367 // need to move right to get it in view: move right just enough so 1368 // that the entire rectangle is in view (or at least the first 1369 // screen size chunk). 1370 1371 if (rect.width() > width) { 1372 // just enough to get screen size chunk on 1373 scrollXDelta += (rect.left - screenLeft); 1374 } else { 1375 // get entire rect at right of screen 1376 scrollXDelta += (rect.right - screenRight); 1377 } 1378 1379 // make sure we aren't scrolling beyond the end of our content 1380 int right = getChildAt(0).getRight(); 1381 int distanceToRight = right - screenRight; 1382 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1383 1384 } else if (rect.left < screenLeft && rect.right < screenRight) { 1385 // need to move right to get it in view: move right just enough so that 1386 // entire rectangle is in view (or at least the first screen 1387 // size chunk of it). 1388 1389 if (rect.width() > width) { 1390 // screen size chunk 1391 scrollXDelta -= (screenRight - rect.right); 1392 } else { 1393 // entire rect at left 1394 scrollXDelta -= (screenLeft - rect.left); 1395 } 1396 1397 // make sure we aren't scrolling any further than the left our content 1398 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1399 } 1400 return scrollXDelta; 1401 } 1402 1403 @Override 1404 public void requestChildFocus(View child, View focused) { 1405 if (!mIsLayoutDirty) { 1406 scrollToChild(focused); 1407 } else { 1408 // The child may not be laid out yet, we can't compute the scroll yet 1409 mChildToScrollTo = focused; 1410 } 1411 super.requestChildFocus(child, focused); 1412 } 1413 1414 1415 /** 1416 * When looking for focus in children of a scroll view, need to be a little 1417 * more careful not to give focus to something that is scrolled off screen. 1418 * 1419 * This is more expensive than the default {@link android.view.ViewGroup} 1420 * implementation, otherwise this behavior might have been made the default. 1421 */ 1422 @Override 1423 protected boolean onRequestFocusInDescendants(int direction, 1424 Rect previouslyFocusedRect) { 1425 1426 // convert from forward / backward notation to up / down / left / right 1427 // (ugh). 1428 if (direction == View.FOCUS_FORWARD) { 1429 direction = View.FOCUS_RIGHT; 1430 } else if (direction == View.FOCUS_BACKWARD) { 1431 direction = View.FOCUS_LEFT; 1432 } 1433 1434 final View nextFocus = previouslyFocusedRect == null ? 1435 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1436 FocusFinder.getInstance().findNextFocusFromRect(this, 1437 previouslyFocusedRect, direction); 1438 1439 if (nextFocus == null) { 1440 return false; 1441 } 1442 1443 if (isOffScreen(nextFocus)) { 1444 return false; 1445 } 1446 1447 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1448 } 1449 1450 @Override 1451 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1452 boolean immediate) { 1453 // offset into coordinate space of this scroll view 1454 rectangle.offset(child.getLeft() - child.getScrollX(), 1455 child.getTop() - child.getScrollY()); 1456 1457 return scrollToChildRect(rectangle, immediate); 1458 } 1459 1460 @Override 1461 public void requestLayout() { 1462 mIsLayoutDirty = true; 1463 super.requestLayout(); 1464 } 1465 1466 @Override 1467 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1468 int childWidth = 0; 1469 int childMargins = 0; 1470 1471 if (getChildCount() > 0) { 1472 childWidth = getChildAt(0).getMeasuredWidth(); 1473 LayoutParams childParams = (LayoutParams) getChildAt(0).getLayoutParams(); 1474 childMargins = childParams.leftMargin + childParams.rightMargin; 1475 } 1476 1477 final int available = r - l - getPaddingLeftWithForeground() - 1478 getPaddingRightWithForeground() - childMargins; 1479 1480 final boolean forceLeftGravity = (childWidth > available); 1481 1482 layoutChildren(l, t, r, b, forceLeftGravity); 1483 1484 mIsLayoutDirty = false; 1485 // Give a child focus if it needs it 1486 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1487 scrollToChild(mChildToScrollTo); 1488 } 1489 mChildToScrollTo = null; 1490 1491 if (!isLaidOut()) { 1492 final int scrollRange = Math.max(0, 1493 childWidth - (r - l - mPaddingLeft - mPaddingRight)); 1494 if (mSavedState != null) { 1495 if (isLayoutRtl() == mSavedState.isLayoutRtl) { 1496 mScrollX = mSavedState.scrollPosition; 1497 } else { 1498 mScrollX = scrollRange - mSavedState.scrollPosition; 1499 } 1500 mSavedState = null; 1501 } else { 1502 if (isLayoutRtl()) { 1503 mScrollX = scrollRange - mScrollX; 1504 } // mScrollX default value is "0" for LTR 1505 } 1506 // Don't forget to clamp 1507 if (mScrollX > scrollRange) { 1508 mScrollX = scrollRange; 1509 } else if (mScrollX < 0) { 1510 mScrollX = 0; 1511 } 1512 } 1513 1514 // Calling this with the present values causes it to re-claim them 1515 scrollTo(mScrollX, mScrollY); 1516 } 1517 1518 @Override 1519 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1520 super.onSizeChanged(w, h, oldw, oldh); 1521 1522 View currentFocused = findFocus(); 1523 if (null == currentFocused || this == currentFocused) 1524 return; 1525 1526 final int maxJump = mRight - mLeft; 1527 1528 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1529 currentFocused.getDrawingRect(mTempRect); 1530 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1531 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1532 doScrollX(scrollDelta); 1533 } 1534 } 1535 1536 /** 1537 * Return true if child is a descendant of parent, (or equal to the parent). 1538 */ 1539 private static boolean isViewDescendantOf(View child, View parent) { 1540 if (child == parent) { 1541 return true; 1542 } 1543 1544 final ViewParent theParent = child.getParent(); 1545 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1546 } 1547 1548 /** 1549 * Fling the scroll view 1550 * 1551 * @param velocityX The initial velocity in the X direction. Positive 1552 * numbers mean that the finger/cursor is moving down the screen, 1553 * which means we want to scroll towards the left. 1554 */ 1555 public void fling(int velocityX) { 1556 if (getChildCount() > 0) { 1557 int width = getWidth() - mPaddingRight - mPaddingLeft; 1558 int right = getChildAt(0).getWidth(); 1559 1560 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1561 Math.max(0, right - width), 0, 0, width/2, 0); 1562 1563 final boolean movingRight = velocityX > 0; 1564 1565 View currentFocused = findFocus(); 1566 View newFocused = findFocusableViewInMyBounds(movingRight, 1567 mScroller.getFinalX(), currentFocused); 1568 1569 if (newFocused == null) { 1570 newFocused = this; 1571 } 1572 1573 if (newFocused != currentFocused) { 1574 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1575 } 1576 1577 postInvalidateOnAnimation(); 1578 } 1579 } 1580 1581 /** 1582 * {@inheritDoc} 1583 * 1584 * <p>This version also clamps the scrolling to the bounds of our child. 1585 */ 1586 @Override 1587 public void scrollTo(int x, int y) { 1588 // we rely on the fact the View.scrollBy calls scrollTo. 1589 if (getChildCount() > 0) { 1590 View child = getChildAt(0); 1591 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1592 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1593 if (x != mScrollX || y != mScrollY) { 1594 super.scrollTo(x, y); 1595 } 1596 } 1597 } 1598 1599 @Override 1600 public void setOverScrollMode(int mode) { 1601 if (mode != OVER_SCROLL_NEVER) { 1602 if (mEdgeGlowLeft == null) { 1603 Context context = getContext(); 1604 mEdgeGlowLeft = new EdgeEffect(context); 1605 mEdgeGlowRight = new EdgeEffect(context); 1606 } 1607 } else { 1608 mEdgeGlowLeft = null; 1609 mEdgeGlowRight = null; 1610 } 1611 super.setOverScrollMode(mode); 1612 } 1613 1614 @SuppressWarnings({"SuspiciousNameCombination"}) 1615 @Override 1616 public void draw(Canvas canvas) { 1617 super.draw(canvas); 1618 if (mEdgeGlowLeft != null) { 1619 final int scrollX = mScrollX; 1620 if (!mEdgeGlowLeft.isFinished()) { 1621 final int restoreCount = canvas.save(); 1622 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1623 1624 canvas.rotate(270); 1625 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1626 mEdgeGlowLeft.setSize(height, getWidth()); 1627 if (mEdgeGlowLeft.draw(canvas)) { 1628 postInvalidateOnAnimation(); 1629 } 1630 canvas.restoreToCount(restoreCount); 1631 } 1632 if (!mEdgeGlowRight.isFinished()) { 1633 final int restoreCount = canvas.save(); 1634 final int width = getWidth(); 1635 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1636 1637 canvas.rotate(90); 1638 canvas.translate(-mPaddingTop, 1639 -(Math.max(getScrollRange(), scrollX) + width)); 1640 mEdgeGlowRight.setSize(height, width); 1641 if (mEdgeGlowRight.draw(canvas)) { 1642 postInvalidateOnAnimation(); 1643 } 1644 canvas.restoreToCount(restoreCount); 1645 } 1646 } 1647 } 1648 1649 private static int clamp(int n, int my, int child) { 1650 if (my >= child || n < 0) { 1651 return 0; 1652 } 1653 if ((my + n) > child) { 1654 return child - my; 1655 } 1656 return n; 1657 } 1658 1659 @Override 1660 protected void onRestoreInstanceState(Parcelable state) { 1661 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1662 // Some old apps reused IDs in ways they shouldn't have. 1663 // Don't break them, but they don't get scroll state restoration. 1664 super.onRestoreInstanceState(state); 1665 return; 1666 } 1667 SavedState ss = (SavedState) state; 1668 super.onRestoreInstanceState(ss.getSuperState()); 1669 mSavedState = ss; 1670 requestLayout(); 1671 } 1672 1673 @Override 1674 protected Parcelable onSaveInstanceState() { 1675 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1676 // Some old apps reused IDs in ways they shouldn't have. 1677 // Don't break them, but they don't get scroll state restoration. 1678 return super.onSaveInstanceState(); 1679 } 1680 Parcelable superState = super.onSaveInstanceState(); 1681 SavedState ss = new SavedState(superState); 1682 ss.scrollPosition = mScrollX; 1683 ss.isLayoutRtl = isLayoutRtl(); 1684 return ss; 1685 } 1686 1687 static class SavedState extends BaseSavedState { 1688 public int scrollPosition; 1689 public boolean isLayoutRtl; 1690 1691 SavedState(Parcelable superState) { 1692 super(superState); 1693 } 1694 1695 public SavedState(Parcel source) { 1696 super(source); 1697 scrollPosition = source.readInt(); 1698 isLayoutRtl = (source.readInt() == 0) ? true : false; 1699 } 1700 1701 @Override 1702 public void writeToParcel(Parcel dest, int flags) { 1703 super.writeToParcel(dest, flags); 1704 dest.writeInt(scrollPosition); 1705 dest.writeInt(isLayoutRtl ? 1 : 0); 1706 } 1707 1708 @Override 1709 public String toString() { 1710 return "HorizontalScrollView.SavedState{" 1711 + Integer.toHexString(System.identityHashCode(this)) 1712 + " scrollPosition=" + scrollPosition 1713 + " isLayoutRtl=" + isLayoutRtl + "}"; 1714 } 1715 1716 public static final Parcelable.Creator<SavedState> CREATOR 1717 = new Parcelable.Creator<SavedState>() { 1718 public SavedState createFromParcel(Parcel in) { 1719 return new SavedState(in); 1720 } 1721 1722 public SavedState[] newArray(int size) { 1723 return new SavedState[size]; 1724 } 1725 }; 1726 } 1727 } 1728
