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