1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.widget; 18 19 import android.content.Context; 20 import android.content.res.TypedArray; 21 import android.graphics.Canvas; 22 import android.graphics.Rect; 23 import android.os.Build; 24 import android.os.Bundle; 25 import android.os.Parcel; 26 import android.os.Parcelable; 27 import android.util.AttributeSet; 28 import android.util.Log; 29 import android.view.FocusFinder; 30 import android.view.InputDevice; 31 import android.view.KeyEvent; 32 import android.view.MotionEvent; 33 import android.view.VelocityTracker; 34 import android.view.View; 35 import android.view.ViewConfiguration; 36 import android.view.ViewDebug; 37 import android.view.ViewGroup; 38 import android.view.ViewParent; 39 import android.view.accessibility.AccessibilityEvent; 40 import android.view.accessibility.AccessibilityNodeInfo; 41 import android.view.animation.AnimationUtils; 42 43 import java.util.List; 44 45 /** 46 * Layout container for a view hierarchy that can be scrolled by the user, 47 * allowing it to be larger than the physical display. A HorizontalScrollView 48 * is a {@link FrameLayout}, meaning you should place one child in it 49 * containing the entire contents to scroll; this child may itself be a layout 50 * manager with a complex hierarchy of objects. A child that is often used 51 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 52 * array of top-level items that the user can scroll through. 53 * 54 * <p>The {@link TextView} class also 55 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 56 * using the two together is possible to achieve the effect of a text view 57 * within a larger container. 58 * 59 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 60 * use either {@link ScrollView} or {@link ListView}. 61 * 62 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 63 */ 64 public class HorizontalScrollView extends FrameLayout { 65 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 66 67 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 68 69 private static final String TAG = "HorizontalScrollView"; 70 71 private long mLastScroll; 72 73 private final Rect mTempRect = new Rect(); 74 private OverScroller mScroller; 75 private EdgeEffect mEdgeGlowLeft; 76 private EdgeEffect mEdgeGlowRight; 77 78 /** 79 * Position of the last motion event. 80 */ 81 private int mLastMotionX; 82 83 /** 84 * True when the layout has changed but the traversal has not come through yet. 85 * Ideally the view hierarchy would keep track of this for us. 86 */ 87 private boolean mIsLayoutDirty = true; 88 89 /** 90 * The child to give focus to in the event that a child has requested focus while the 91 * layout is dirty. This prevents the scroll from being wrong if the child has not been 92 * laid out before requesting focus. 93 */ 94 private View mChildToScrollTo = null; 95 96 /** 97 * True if the user is currently dragging this ScrollView around. This is 98 * not the same as 'is being flinged', which can be checked by 99 * mScroller.isFinished() (flinging begins when the user lifts his finger). 100 */ 101 private boolean mIsBeingDragged = false; 102 103 /** 104 * Determines speed during touch scrolling 105 */ 106 private VelocityTracker mVelocityTracker; 107 108 /** 109 * When set to true, the scroll view measure its child to make it fill the currently 110 * visible area. 111 */ 112 @ViewDebug.ExportedProperty(category = "layout") 113 private boolean mFillViewport; 114 115 /** 116 * Whether arrow scrolling is animated. 117 */ 118 private boolean mSmoothScrollingEnabled = true; 119 120 private int mTouchSlop; 121 private int mMinimumVelocity; 122 private int mMaximumVelocity; 123 124 private int mOverscrollDistance; 125 private int mOverflingDistance; 126 127 /** 128 * ID of the active pointer. This is used to retain consistency during 129 * drags/flings if multiple pointers are used. 130 */ 131 private int mActivePointerId = INVALID_POINTER; 132 133 /** 134 * Sentinel value for no current active pointer. 135 * Used by {@link #mActivePointerId}. 136 */ 137 private static final int INVALID_POINTER = -1; 138 139 private SavedState mSavedState; 140 141 public HorizontalScrollView(Context context) { 142 this(context, null); 143 } 144 145 public HorizontalScrollView(Context context, AttributeSet attrs) { 146 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 147 } 148 149 public HorizontalScrollView(Context context, AttributeSet attrs, int 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 @Override 765 public boolean performAccessibilityAction(int action, Bundle arguments) { 766 if (super.performAccessibilityAction(action, arguments)) { 767 return true; 768 } 769 switch (action) { 770 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 771 if (!isEnabled()) { 772 return false; 773 } 774 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 775 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 776 if (targetScrollX != mScrollX) { 777 smoothScrollTo(targetScrollX, 0); 778 return true; 779 } 780 } return false; 781 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 782 if (!isEnabled()) { 783 return false; 784 } 785 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 786 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 787 if (targetScrollX != mScrollX) { 788 smoothScrollTo(targetScrollX, 0); 789 return true; 790 } 791 } return false; 792 } 793 return false; 794 } 795 796 @Override 797 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 798 super.onInitializeAccessibilityNodeInfo(info); 799 info.setClassName(HorizontalScrollView.class.getName()); 800 final int scrollRange = getScrollRange(); 801 if (scrollRange > 0) { 802 info.setScrollable(true); 803 if (isEnabled() && mScrollX > 0) { 804 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 805 } 806 if (isEnabled() && mScrollX < scrollRange) { 807 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 808 } 809 } 810 } 811 812 @Override 813 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 814 super.onInitializeAccessibilityEvent(event); 815 event.setClassName(HorizontalScrollView.class.getName()); 816 event.setScrollable(getScrollRange() > 0); 817 event.setScrollX(mScrollX); 818 event.setScrollY(mScrollY); 819 event.setMaxScrollX(getScrollRange()); 820 event.setMaxScrollY(mScrollY); 821 } 822 823 private int getScrollRange() { 824 int scrollRange = 0; 825 if (getChildCount() > 0) { 826 View child = getChildAt(0); 827 scrollRange = Math.max(0, 828 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 829 } 830 return scrollRange; 831 } 832 833 /** 834 * <p> 835 * Finds the next focusable component that fits in this View's bounds 836 * (excluding fading edges) pretending that this View's left is located at 837 * the parameter left. 838 * </p> 839 * 840 * @param leftFocus look for a candidate is the one at the left of the bounds 841 * if leftFocus is true, or at the right of the bounds if leftFocus 842 * is false 843 * @param left the left offset of the bounds in which a focusable must be 844 * found (the fading edge is assumed to start at this position) 845 * @param preferredFocusable the View that has highest priority and will be 846 * returned if it is within my bounds (null is valid) 847 * @return the next focusable component in the bounds or null if none can be found 848 */ 849 private View findFocusableViewInMyBounds(final boolean leftFocus, 850 final int left, View preferredFocusable) { 851 /* 852 * The fading edge's transparent side should be considered for focus 853 * since it's mostly visible, so we divide the actual fading edge length 854 * by 2. 855 */ 856 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 857 final int leftWithoutFadingEdge = left + fadingEdgeLength; 858 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 859 860 if ((preferredFocusable != null) 861 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 862 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 863 return preferredFocusable; 864 } 865 866 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 867 rightWithoutFadingEdge); 868 } 869 870 /** 871 * <p> 872 * Finds the next focusable component that fits in the specified bounds. 873 * </p> 874 * 875 * @param leftFocus look for a candidate is the one at the left of the bounds 876 * if leftFocus is true, or at the right of the bounds if 877 * leftFocus is false 878 * @param left the left offset of the bounds in which a focusable must be 879 * found 880 * @param right the right offset of the bounds in which a focusable must 881 * be found 882 * @return the next focusable component in the bounds or null if none can 883 * be found 884 */ 885 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 886 887 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 888 View focusCandidate = null; 889 890 /* 891 * A fully contained focusable is one where its left is below the bound's 892 * left, and its right is above the bound's right. A partially 893 * contained focusable is one where some part of it is within the 894 * bounds, but it also has some part that is not within bounds. A fully contained 895 * focusable is preferred to a partially contained focusable. 896 */ 897 boolean foundFullyContainedFocusable = false; 898 899 int count = focusables.size(); 900 for (int i = 0; i < count; i++) { 901 View view = focusables.get(i); 902 int viewLeft = view.getLeft(); 903 int viewRight = view.getRight(); 904 905 if (left < viewRight && viewLeft < right) { 906 /* 907 * the focusable is in the target area, it is a candidate for 908 * focusing 909 */ 910 911 final boolean viewIsFullyContained = (left < viewLeft) && 912 (viewRight < right); 913 914 if (focusCandidate == null) { 915 /* No candidate, take this one */ 916 focusCandidate = view; 917 foundFullyContainedFocusable = viewIsFullyContained; 918 } else { 919 final boolean viewIsCloserToBoundary = 920 (leftFocus && viewLeft < focusCandidate.getLeft()) || 921 (!leftFocus && viewRight > focusCandidate.getRight()); 922 923 if (foundFullyContainedFocusable) { 924 if (viewIsFullyContained && viewIsCloserToBoundary) { 925 /* 926 * We're dealing with only fully contained views, so 927 * it has to be closer to the boundary to beat our 928 * candidate 929 */ 930 focusCandidate = view; 931 } 932 } else { 933 if (viewIsFullyContained) { 934 /* Any fully contained view beats a partially contained view */ 935 focusCandidate = view; 936 foundFullyContainedFocusable = true; 937 } else if (viewIsCloserToBoundary) { 938 /* 939 * Partially contained view beats another partially 940 * contained view if it's closer 941 */ 942 focusCandidate = view; 943 } 944 } 945 } 946 } 947 } 948 949 return focusCandidate; 950 } 951 952 /** 953 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 954 * method will scroll the view by one page left or right and give the focus 955 * to the leftmost/rightmost component in the new visible area. If no 956 * component is a good candidate for focus, this scrollview reclaims the 957 * focus.</p> 958 * 959 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 960 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 961 * to go one page right 962 * @return true if the key event is consumed by this method, false otherwise 963 */ 964 public boolean pageScroll(int direction) { 965 boolean right = direction == View.FOCUS_RIGHT; 966 int width = getWidth(); 967 968 if (right) { 969 mTempRect.left = getScrollX() + width; 970 int count = getChildCount(); 971 if (count > 0) { 972 View view = getChildAt(0); 973 if (mTempRect.left + width > view.getRight()) { 974 mTempRect.left = view.getRight() - width; 975 } 976 } 977 } else { 978 mTempRect.left = getScrollX() - width; 979 if (mTempRect.left < 0) { 980 mTempRect.left = 0; 981 } 982 } 983 mTempRect.right = mTempRect.left + width; 984 985 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 986 } 987 988 /** 989 * <p>Handles scrolling in response to a "home/end" shortcut press. This 990 * method will scroll the view to the left or right and give the focus 991 * to the leftmost/rightmost component in the new visible area. If no 992 * component is a good candidate for focus, this scrollview reclaims the 993 * focus.</p> 994 * 995 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 996 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 997 * to go the right 998 * @return true if the key event is consumed by this method, false otherwise 999 */ 1000 public boolean fullScroll(int direction) { 1001 boolean right = direction == View.FOCUS_RIGHT; 1002 int width = getWidth(); 1003 1004 mTempRect.left = 0; 1005 mTempRect.right = width; 1006 1007 if (right) { 1008 int count = getChildCount(); 1009 if (count > 0) { 1010 View view = getChildAt(0); 1011 mTempRect.right = view.getRight(); 1012 mTempRect.left = mTempRect.right - width; 1013 } 1014 } 1015 1016 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 1017 } 1018 1019 /** 1020 * <p>Scrolls the view to make the area defined by <code>left</code> and 1021 * <code>right</code> visible. This method attempts to give the focus 1022 * to a component visible in this area. If no component can be focused in 1023 * the new visible area, the focus is reclaimed by this scrollview.</p> 1024 * 1025 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 1026 * to go left {@link android.view.View#FOCUS_RIGHT} to right 1027 * @param left the left offset of the new area to be made visible 1028 * @param right the right offset of the new area to be made visible 1029 * @return true if the key event is consumed by this method, false otherwise 1030 */ 1031 private boolean scrollAndFocus(int direction, int left, int right) { 1032 boolean handled = true; 1033 1034 int width = getWidth(); 1035 int containerLeft = getScrollX(); 1036 int containerRight = containerLeft + width; 1037 boolean goLeft = direction == View.FOCUS_LEFT; 1038 1039 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1040 if (newFocused == null) { 1041 newFocused = this; 1042 } 1043 1044 if (left >= containerLeft && right <= containerRight) { 1045 handled = false; 1046 } else { 1047 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1048 doScrollX(delta); 1049 } 1050 1051 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1052 1053 return handled; 1054 } 1055 1056 /** 1057 * Handle scrolling in response to a left or right arrow click. 1058 * 1059 * @param direction The direction corresponding to the arrow key that was 1060 * pressed 1061 * @return True if we consumed the event, false otherwise 1062 */ 1063 public boolean arrowScroll(int direction) { 1064 1065 View currentFocused = findFocus(); 1066 if (currentFocused == this) currentFocused = null; 1067 1068 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1069 1070 final int maxJump = getMaxScrollAmount(); 1071 1072 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1073 nextFocused.getDrawingRect(mTempRect); 1074 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1075 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1076 doScrollX(scrollDelta); 1077 nextFocused.requestFocus(direction); 1078 } else { 1079 // no new focus 1080 int scrollDelta = maxJump; 1081 1082 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1083 scrollDelta = getScrollX(); 1084 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1085 1086 int daRight = getChildAt(0).getRight(); 1087 1088 int screenRight = getScrollX() + getWidth(); 1089 1090 if (daRight - screenRight < maxJump) { 1091 scrollDelta = daRight - screenRight; 1092 } 1093 } 1094 if (scrollDelta == 0) { 1095 return false; 1096 } 1097 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1098 } 1099 1100 if (currentFocused != null && currentFocused.isFocused() 1101 && isOffScreen(currentFocused)) { 1102 // previously focused item still has focus and is off screen, give 1103 // it up (take it back to ourselves) 1104 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1105 // sure to 1106 // get it) 1107 final int descendantFocusability = getDescendantFocusability(); // save 1108 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1109 requestFocus(); 1110 setDescendantFocusability(descendantFocusability); // restore 1111 } 1112 return true; 1113 } 1114 1115 /** 1116 * @return whether the descendant of this scroll view is scrolled off 1117 * screen. 1118 */ 1119 private boolean isOffScreen(View descendant) { 1120 return !isWithinDeltaOfScreen(descendant, 0); 1121 } 1122 1123 /** 1124 * @return whether the descendant of this scroll view is within delta 1125 * pixels of being on the screen. 1126 */ 1127 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1128 descendant.getDrawingRect(mTempRect); 1129 offsetDescendantRectToMyCoords(descendant, mTempRect); 1130 1131 return (mTempRect.right + delta) >= getScrollX() 1132 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1133 } 1134 1135 /** 1136 * Smooth scroll by a X delta 1137 * 1138 * @param delta the number of pixels to scroll by on the X axis 1139 */ 1140 private void doScrollX(int delta) { 1141 if (delta != 0) { 1142 if (mSmoothScrollingEnabled) { 1143 smoothScrollBy(delta, 0); 1144 } else { 1145 scrollBy(delta, 0); 1146 } 1147 } 1148 } 1149 1150 /** 1151 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1152 * 1153 * @param dx the number of pixels to scroll by on the X axis 1154 * @param dy the number of pixels to scroll by on the Y axis 1155 */ 1156 public final void smoothScrollBy(int dx, int dy) { 1157 if (getChildCount() == 0) { 1158 // Nothing to do. 1159 return; 1160 } 1161 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1162 if (duration > ANIMATED_SCROLL_GAP) { 1163 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1164 final int right = getChildAt(0).getWidth(); 1165 final int maxX = Math.max(0, right - width); 1166 final int scrollX = mScrollX; 1167 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1168 1169 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1170 postInvalidateOnAnimation(); 1171 } else { 1172 if (!mScroller.isFinished()) { 1173 mScroller.abortAnimation(); 1174 } 1175 scrollBy(dx, dy); 1176 } 1177 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1178 } 1179 1180 /** 1181 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1182 * 1183 * @param x the position where to scroll on the X axis 1184 * @param y the position where to scroll on the Y axis 1185 */ 1186 public final void smoothScrollTo(int x, int y) { 1187 smoothScrollBy(x - mScrollX, y - mScrollY); 1188 } 1189 1190 /** 1191 * <p>The scroll range of a scroll view is the overall width of all of its 1192 * children.</p> 1193 */ 1194 @Override 1195 protected int computeHorizontalScrollRange() { 1196 final int count = getChildCount(); 1197 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1198 if (count == 0) { 1199 return contentWidth; 1200 } 1201 1202 int scrollRange = getChildAt(0).getRight(); 1203 final int scrollX = mScrollX; 1204 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1205 if (scrollX < 0) { 1206 scrollRange -= scrollX; 1207 } else if (scrollX > overscrollRight) { 1208 scrollRange += scrollX - overscrollRight; 1209 } 1210 1211 return scrollRange; 1212 } 1213 1214 @Override 1215 protected int computeHorizontalScrollOffset() { 1216 return Math.max(0, super.computeHorizontalScrollOffset()); 1217 } 1218 1219 @Override 1220 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1221 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1222 1223 int childWidthMeasureSpec; 1224 int childHeightMeasureSpec; 1225 1226 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1227 + mPaddingBottom, lp.height); 1228 1229 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1230 1231 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1232 } 1233 1234 @Override 1235 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1236 int parentHeightMeasureSpec, int heightUsed) { 1237 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1238 1239 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1240 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1241 + heightUsed, lp.height); 1242 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1243 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1244 1245 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1246 } 1247 1248 @Override 1249 public void computeScroll() { 1250 if (mScroller.computeScrollOffset()) { 1251 // This is called at drawing time by ViewGroup. We don't want to 1252 // re-show the scrollbars at this point, which scrollTo will do, 1253 // so we replicate most of scrollTo here. 1254 // 1255 // It's a little odd to call onScrollChanged from inside the drawing. 1256 // 1257 // It is, except when you remember that computeScroll() is used to 1258 // animate scrolling. So unless we want to defer the onScrollChanged() 1259 // until the end of the animated scrolling, we don't really have a 1260 // choice here. 1261 // 1262 // I agree. The alternative, which I think would be worse, is to post 1263 // something and tell the subclasses later. This is bad because there 1264 // will be a window where mScrollX/Y is different from what the app 1265 // thinks it is. 1266 // 1267 int oldX = mScrollX; 1268 int oldY = mScrollY; 1269 int x = mScroller.getCurrX(); 1270 int y = mScroller.getCurrY(); 1271 1272 if (oldX != x || oldY != y) { 1273 final int range = getScrollRange(); 1274 final int overscrollMode = getOverScrollMode(); 1275 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1276 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1277 1278 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1279 mOverflingDistance, 0, false); 1280 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1281 1282 if (canOverscroll) { 1283 if (x < 0 && oldX >= 0) { 1284 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1285 } else if (x > range && oldX <= range) { 1286 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1287 } 1288 } 1289 } 1290 1291 if (!awakenScrollBars()) { 1292 postInvalidateOnAnimation(); 1293 } 1294 } 1295 } 1296 1297 /** 1298 * Scrolls the view to the given child. 1299 * 1300 * @param child the View to scroll to 1301 */ 1302 private void scrollToChild(View child) { 1303 child.getDrawingRect(mTempRect); 1304 1305 /* Offset from child's local coordinates to ScrollView coordinates */ 1306 offsetDescendantRectToMyCoords(child, mTempRect); 1307 1308 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1309 1310 if (scrollDelta != 0) { 1311 scrollBy(scrollDelta, 0); 1312 } 1313 } 1314 1315 /** 1316 * If rect is off screen, scroll just enough to get it (or at least the 1317 * first screen size chunk of it) on screen. 1318 * 1319 * @param rect The rectangle. 1320 * @param immediate True to scroll immediately without animation 1321 * @return true if scrolling was performed 1322 */ 1323 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1324 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1325 final boolean scroll = delta != 0; 1326 if (scroll) { 1327 if (immediate) { 1328 scrollBy(delta, 0); 1329 } else { 1330 smoothScrollBy(delta, 0); 1331 } 1332 } 1333 return scroll; 1334 } 1335 1336 /** 1337 * Compute the amount to scroll in the X direction in order to get 1338 * a rectangle completely on the screen (or, if taller than the screen, 1339 * at least the first screen size chunk of it). 1340 * 1341 * @param rect The rect. 1342 * @return The scroll delta. 1343 */ 1344 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1345 if (getChildCount() == 0) return 0; 1346 1347 int width = getWidth(); 1348 int screenLeft = getScrollX(); 1349 int screenRight = screenLeft + width; 1350 1351 int fadingEdge = getHorizontalFadingEdgeLength(); 1352 1353 // leave room for left fading edge as long as rect isn't at very left 1354 if (rect.left > 0) { 1355 screenLeft += fadingEdge; 1356 } 1357 1358 // leave room for right fading edge as long as rect isn't at very right 1359 if (rect.right < getChildAt(0).getWidth()) { 1360 screenRight -= fadingEdge; 1361 } 1362 1363 int scrollXDelta = 0; 1364 1365 if (rect.right > screenRight && rect.left > screenLeft) { 1366 // need to move right to get it in view: move right just enough so 1367 // that the entire rectangle is in view (or at least the first 1368 // screen size chunk). 1369 1370 if (rect.width() > width) { 1371 // just enough to get screen size chunk on 1372 scrollXDelta += (rect.left - screenLeft); 1373 } else { 1374 // get entire rect at right of screen 1375 scrollXDelta += (rect.right - screenRight); 1376 } 1377 1378 // make sure we aren't scrolling beyond the end of our content 1379 int right = getChildAt(0).getRight(); 1380 int distanceToRight = right - screenRight; 1381 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1382 1383 } else if (rect.left < screenLeft && rect.right < screenRight) { 1384 // need to move right to get it in view: move right just enough so that 1385 // entire rectangle is in view (or at least the first screen 1386 // size chunk of it). 1387 1388 if (rect.width() > width) { 1389 // screen size chunk 1390 scrollXDelta -= (screenRight - rect.right); 1391 } else { 1392 // entire rect at left 1393 scrollXDelta -= (screenLeft - rect.left); 1394 } 1395 1396 // make sure we aren't scrolling any further than the left our content 1397 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1398 } 1399 return scrollXDelta; 1400 } 1401 1402 @Override 1403 public void requestChildFocus(View child, View focused) { 1404 if (!mIsLayoutDirty) { 1405 scrollToChild(focused); 1406 } else { 1407 // The child may not be laid out yet, we can't compute the scroll yet 1408 mChildToScrollTo = focused; 1409 } 1410 super.requestChildFocus(child, focused); 1411 } 1412 1413 1414 /** 1415 * When looking for focus in children of a scroll view, need to be a little 1416 * more careful not to give focus to something that is scrolled off screen. 1417 * 1418 * This is more expensive than the default {@link android.view.ViewGroup} 1419 * implementation, otherwise this behavior might have been made the default. 1420 */ 1421 @Override 1422 protected boolean onRequestFocusInDescendants(int direction, 1423 Rect previouslyFocusedRect) { 1424 1425 // convert from forward / backward notation to up / down / left / right 1426 // (ugh). 1427 if (direction == View.FOCUS_FORWARD) { 1428 direction = View.FOCUS_RIGHT; 1429 } else if (direction == View.FOCUS_BACKWARD) { 1430 direction = View.FOCUS_LEFT; 1431 } 1432 1433 final View nextFocus = previouslyFocusedRect == null ? 1434 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1435 FocusFinder.getInstance().findNextFocusFromRect(this, 1436 previouslyFocusedRect, direction); 1437 1438 if (nextFocus == null) { 1439 return false; 1440 } 1441 1442 if (isOffScreen(nextFocus)) { 1443 return false; 1444 } 1445 1446 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1447 } 1448 1449 @Override 1450 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1451 boolean immediate) { 1452 // offset into coordinate space of this scroll view 1453 rectangle.offset(child.getLeft() - child.getScrollX(), 1454 child.getTop() - child.getScrollY()); 1455 1456 return scrollToChildRect(rectangle, immediate); 1457 } 1458 1459 @Override 1460 public void requestLayout() { 1461 mIsLayoutDirty = true; 1462 super.requestLayout(); 1463 } 1464 1465 @Override 1466 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1467 int childWidth = 0; 1468 int childMargins = 0; 1469 1470 if (getChildCount() > 0) { 1471 childWidth = getChildAt(0).getMeasuredWidth(); 1472 LayoutParams childParams = (LayoutParams) getChildAt(0).getLayoutParams(); 1473 childMargins = childParams.leftMargin + childParams.rightMargin; 1474 } 1475 1476 final int available = r - l - getPaddingLeftWithForeground() - 1477 getPaddingRightWithForeground() - childMargins; 1478 1479 final boolean forceLeftGravity = (childWidth > available); 1480 1481 layoutChildren(l, t, r, b, forceLeftGravity); 1482 1483 mIsLayoutDirty = false; 1484 // Give a child focus if it needs it 1485 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1486 scrollToChild(mChildToScrollTo); 1487 } 1488 mChildToScrollTo = null; 1489 1490 if (!isLaidOut()) { 1491 final int scrollRange = Math.max(0, 1492 childWidth - (r - l - mPaddingLeft - mPaddingRight)); 1493 if (mSavedState != null) { 1494 if (isLayoutRtl() == mSavedState.isLayoutRtl) { 1495 mScrollX = mSavedState.scrollPosition; 1496 } else { 1497 mScrollX = scrollRange - mSavedState.scrollPosition; 1498 } 1499 mSavedState = null; 1500 } else { 1501 if (isLayoutRtl()) { 1502 mScrollX = scrollRange - mScrollX; 1503 } // mScrollX default value is "0" for LTR 1504 } 1505 // Don't forget to clamp 1506 if (mScrollX > scrollRange) { 1507 mScrollX = scrollRange; 1508 } else if (mScrollX < 0) { 1509 mScrollX = 0; 1510 } 1511 } 1512 1513 // Calling this with the present values causes it to re-claim them 1514 scrollTo(mScrollX, mScrollY); 1515 } 1516 1517 @Override 1518 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1519 super.onSizeChanged(w, h, oldw, oldh); 1520 1521 View currentFocused = findFocus(); 1522 if (null == currentFocused || this == currentFocused) 1523 return; 1524 1525 final int maxJump = mRight - mLeft; 1526 1527 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1528 currentFocused.getDrawingRect(mTempRect); 1529 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1530 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1531 doScrollX(scrollDelta); 1532 } 1533 } 1534 1535 /** 1536 * Return true if child is a descendant of parent, (or equal to the parent). 1537 */ 1538 private static boolean isViewDescendantOf(View child, View parent) { 1539 if (child == parent) { 1540 return true; 1541 } 1542 1543 final ViewParent theParent = child.getParent(); 1544 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1545 } 1546 1547 /** 1548 * Fling the scroll view 1549 * 1550 * @param velocityX The initial velocity in the X direction. Positive 1551 * numbers mean that the finger/cursor is moving down the screen, 1552 * which means we want to scroll towards the left. 1553 */ 1554 public void fling(int velocityX) { 1555 if (getChildCount() > 0) { 1556 int width = getWidth() - mPaddingRight - mPaddingLeft; 1557 int right = getChildAt(0).getWidth(); 1558 1559 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1560 Math.max(0, right - width), 0, 0, width/2, 0); 1561 1562 final boolean movingRight = velocityX > 0; 1563 1564 View currentFocused = findFocus(); 1565 View newFocused = findFocusableViewInMyBounds(movingRight, 1566 mScroller.getFinalX(), currentFocused); 1567 1568 if (newFocused == null) { 1569 newFocused = this; 1570 } 1571 1572 if (newFocused != currentFocused) { 1573 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1574 } 1575 1576 postInvalidateOnAnimation(); 1577 } 1578 } 1579 1580 /** 1581 * {@inheritDoc} 1582 * 1583 * <p>This version also clamps the scrolling to the bounds of our child. 1584 */ 1585 @Override 1586 public void scrollTo(int x, int y) { 1587 // we rely on the fact the View.scrollBy calls scrollTo. 1588 if (getChildCount() > 0) { 1589 View child = getChildAt(0); 1590 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1591 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1592 if (x != mScrollX || y != mScrollY) { 1593 super.scrollTo(x, y); 1594 } 1595 } 1596 } 1597 1598 @Override 1599 public void setOverScrollMode(int mode) { 1600 if (mode != OVER_SCROLL_NEVER) { 1601 if (mEdgeGlowLeft == null) { 1602 Context context = getContext(); 1603 mEdgeGlowLeft = new EdgeEffect(context); 1604 mEdgeGlowRight = new EdgeEffect(context); 1605 } 1606 } else { 1607 mEdgeGlowLeft = null; 1608 mEdgeGlowRight = null; 1609 } 1610 super.setOverScrollMode(mode); 1611 } 1612 1613 @SuppressWarnings({"SuspiciousNameCombination"}) 1614 @Override 1615 public void draw(Canvas canvas) { 1616 super.draw(canvas); 1617 if (mEdgeGlowLeft != null) { 1618 final int scrollX = mScrollX; 1619 if (!mEdgeGlowLeft.isFinished()) { 1620 final int restoreCount = canvas.save(); 1621 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1622 1623 canvas.rotate(270); 1624 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1625 mEdgeGlowLeft.setSize(height, getWidth()); 1626 if (mEdgeGlowLeft.draw(canvas)) { 1627 postInvalidateOnAnimation(); 1628 } 1629 canvas.restoreToCount(restoreCount); 1630 } 1631 if (!mEdgeGlowRight.isFinished()) { 1632 final int restoreCount = canvas.save(); 1633 final int width = getWidth(); 1634 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1635 1636 canvas.rotate(90); 1637 canvas.translate(-mPaddingTop, 1638 -(Math.max(getScrollRange(), scrollX) + width)); 1639 mEdgeGlowRight.setSize(height, width); 1640 if (mEdgeGlowRight.draw(canvas)) { 1641 postInvalidateOnAnimation(); 1642 } 1643 canvas.restoreToCount(restoreCount); 1644 } 1645 } 1646 } 1647 1648 private static int clamp(int n, int my, int child) { 1649 if (my >= child || n < 0) { 1650 return 0; 1651 } 1652 if ((my + n) > child) { 1653 return child - my; 1654 } 1655 return n; 1656 } 1657 1658 @Override 1659 protected void onRestoreInstanceState(Parcelable state) { 1660 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1661 // Some old apps reused IDs in ways they shouldn't have. 1662 // Don't break them, but they don't get scroll state restoration. 1663 super.onRestoreInstanceState(state); 1664 return; 1665 } 1666 SavedState ss = (SavedState) state; 1667 super.onRestoreInstanceState(ss.getSuperState()); 1668 mSavedState = ss; 1669 requestLayout(); 1670 } 1671 1672 @Override 1673 protected Parcelable onSaveInstanceState() { 1674 if (mContext.getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { 1675 // Some old apps reused IDs in ways they shouldn't have. 1676 // Don't break them, but they don't get scroll state restoration. 1677 return super.onSaveInstanceState(); 1678 } 1679 Parcelable superState = super.onSaveInstanceState(); 1680 SavedState ss = new SavedState(superState); 1681 ss.scrollPosition = mScrollX; 1682 ss.isLayoutRtl = isLayoutRtl(); 1683 return ss; 1684 } 1685 1686 static class SavedState extends BaseSavedState { 1687 public int scrollPosition; 1688 public boolean isLayoutRtl; 1689 1690 SavedState(Parcelable superState) { 1691 super(superState); 1692 } 1693 1694 public SavedState(Parcel source) { 1695 super(source); 1696 scrollPosition = source.readInt(); 1697 isLayoutRtl = (source.readInt() == 0) ? true : false; 1698 } 1699 1700 @Override 1701 public void writeToParcel(Parcel dest, int flags) { 1702 super.writeToParcel(dest, flags); 1703 dest.writeInt(scrollPosition); 1704 dest.writeInt(isLayoutRtl ? 1 : 0); 1705 } 1706 1707 @Override 1708 public String toString() { 1709 return "HorizontalScrollView.SavedState{" 1710 + Integer.toHexString(System.identityHashCode(this)) 1711 + " scrollPosition=" + scrollPosition 1712 + " isLayoutRtl=" + isLayoutRtl + "}"; 1713 } 1714 1715 public static final Parcelable.Creator<SavedState> CREATOR 1716 = new Parcelable.Creator<SavedState>() { 1717 public SavedState createFromParcel(Parcel in) { 1718 return new SavedState(in); 1719 } 1720 1721 public SavedState[] newArray(int size) { 1722 return new SavedState[size]; 1723 } 1724 }; 1725 } 1726 } 1727
