HorizontalScrollView.java revision 9bc30d31322848d61f518c1db43544988faaba8f
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.widget; 18 19import com.android.internal.R; 20 21import android.content.Context; 22import android.content.res.Resources; 23import android.content.res.TypedArray; 24import android.graphics.Canvas; 25import android.graphics.Rect; 26import android.graphics.drawable.Drawable; 27import android.util.AttributeSet; 28import android.view.FocusFinder; 29import android.view.InputDevice; 30import android.view.KeyEvent; 31import android.view.MotionEvent; 32import android.view.VelocityTracker; 33import android.view.View; 34import android.view.ViewConfiguration; 35import android.view.ViewDebug; 36import android.view.ViewGroup; 37import android.view.ViewParent; 38import android.view.animation.AnimationUtils; 39 40import java.util.List; 41 42/** 43 * Layout container for a view hierarchy that can be scrolled by the user, 44 * allowing it to be larger than the physical display. A HorizontalScrollView 45 * is a {@link FrameLayout}, meaning you should place one child in it 46 * containing the entire contents to scroll; this child may itself be a layout 47 * manager with a complex hierarchy of objects. A child that is often used 48 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 49 * array of top-level items that the user can scroll through. 50 * 51 * <p>You should never use a HorizontalScrollView with a {@link ListView}, since 52 * ListView takes care of its own scrolling. Most importantly, doing this 53 * defeats all of the important optimizations in ListView for dealing with 54 * large lists, since it effectively forces the ListView to display its entire 55 * list of items to fill up the infinite container supplied by HorizontalScrollView. 56 * 57 * <p>The {@link TextView} class also 58 * takes care of its own scrolling, so does not require a ScrollView, but 59 * using the two together is possible to achieve the effect of a text view 60 * within a larger container. 61 * 62 * <p>HorizontalScrollView only supports horizontal scrolling. 63 * 64 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 65 */ 66public class HorizontalScrollView extends FrameLayout { 67 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 68 69 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 70 71 72 private long mLastScroll; 73 74 private final Rect mTempRect = new Rect(); 75 private OverScroller mScroller; 76 private EdgeGlow mEdgeGlowLeft; 77 private EdgeGlow mEdgeGlowRight; 78 79 /** 80 * Position of the last motion event. 81 */ 82 private float mLastMotionX; 83 84 /** 85 * True when the layout has changed but the traversal has not come through yet. 86 * Ideally the view hierarchy would keep track of this for us. 87 */ 88 private boolean mIsLayoutDirty = true; 89 90 /** 91 * The child to give focus to in the event that a child has requested focus while the 92 * layout is dirty. This prevents the scroll from being wrong if the child has not been 93 * laid out before requesting focus. 94 */ 95 private View mChildToScrollTo = null; 96 97 /** 98 * True if the user is currently dragging this ScrollView around. This is 99 * not the same as 'is being flinged', which can be checked by 100 * mScroller.isFinished() (flinging begins when the user lifts his finger). 101 */ 102 private boolean mIsBeingDragged = false; 103 104 /** 105 * Determines speed during touch scrolling 106 */ 107 private VelocityTracker mVelocityTracker; 108 109 /** 110 * When set to true, the scroll view measure its child to make it fill the currently 111 * visible area. 112 */ 113 @ViewDebug.ExportedProperty(category = "layout") 114 private boolean mFillViewport; 115 116 /** 117 * Whether arrow scrolling is animated. 118 */ 119 private boolean mSmoothScrollingEnabled = true; 120 121 private int mTouchSlop; 122 private int mMinimumVelocity; 123 private int mMaximumVelocity; 124 125 private int mOverscrollDistance; 126 private int mOverflingDistance; 127 128 /** 129 * ID of the active pointer. This is used to retain consistency during 130 * drags/flings if multiple pointers are used. 131 */ 132 private int mActivePointerId = INVALID_POINTER; 133 134 /** 135 * Sentinel value for no current active pointer. 136 * Used by {@link #mActivePointerId}. 137 */ 138 private static final int INVALID_POINTER = -1; 139 140 public HorizontalScrollView(Context context) { 141 this(context, null); 142 } 143 144 public HorizontalScrollView(Context context, AttributeSet attrs) { 145 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 146 } 147 148 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 149 super(context, attrs, defStyle); 150 initScrollView(); 151 152 TypedArray a = context.obtainStyledAttributes(attrs, 153 android.R.styleable.HorizontalScrollView, defStyle, 0); 154 155 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 156 157 a.recycle(); 158 } 159 160 @Override 161 protected float getLeftFadingEdgeStrength() { 162 if (getChildCount() == 0) { 163 return 0.0f; 164 } 165 166 final int length = getHorizontalFadingEdgeLength(); 167 if (mScrollX < length) { 168 return mScrollX / (float) length; 169 } 170 171 return 1.0f; 172 } 173 174 @Override 175 protected float getRightFadingEdgeStrength() { 176 if (getChildCount() == 0) { 177 return 0.0f; 178 } 179 180 final int length = getHorizontalFadingEdgeLength(); 181 final int rightEdge = getWidth() - mPaddingRight; 182 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 183 if (span < length) { 184 return span / (float) length; 185 } 186 187 return 1.0f; 188 } 189 190 /** 191 * @return The maximum amount this scroll view will scroll in response to 192 * an arrow event. 193 */ 194 public int getMaxScrollAmount() { 195 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 196 } 197 198 199 private void initScrollView() { 200 mScroller = new OverScroller(getContext()); 201 setFocusable(true); 202 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 203 setWillNotDraw(false); 204 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 205 mTouchSlop = configuration.getScaledTouchSlop(); 206 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 207 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 208 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 209 mOverflingDistance = configuration.getScaledOverflingDistance(); 210 } 211 212 @Override 213 public void addView(View child) { 214 if (getChildCount() > 0) { 215 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 216 } 217 218 super.addView(child); 219 } 220 221 @Override 222 public void addView(View child, int index) { 223 if (getChildCount() > 0) { 224 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 225 } 226 227 super.addView(child, index); 228 } 229 230 @Override 231 public void addView(View child, ViewGroup.LayoutParams params) { 232 if (getChildCount() > 0) { 233 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 234 } 235 236 super.addView(child, params); 237 } 238 239 @Override 240 public void addView(View child, int index, ViewGroup.LayoutParams params) { 241 if (getChildCount() > 0) { 242 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 243 } 244 245 super.addView(child, index, params); 246 } 247 248 /** 249 * @return Returns true this HorizontalScrollView can be scrolled 250 */ 251 private boolean canScroll() { 252 View child = getChildAt(0); 253 if (child != null) { 254 int childWidth = child.getWidth(); 255 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 256 } 257 return false; 258 } 259 260 /** 261 * Indicates whether this HorizontalScrollView's content is stretched to 262 * fill the viewport. 263 * 264 * @return True if the content fills the viewport, false otherwise. 265 * 266 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 267 */ 268 public boolean isFillViewport() { 269 return mFillViewport; 270 } 271 272 /** 273 * Indicates this HorizontalScrollView whether it should stretch its content width 274 * to fill the viewport or not. 275 * 276 * @param fillViewport True to stretch the content's width to the viewport's 277 * boundaries, false otherwise. 278 * 279 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 280 */ 281 public void setFillViewport(boolean fillViewport) { 282 if (fillViewport != mFillViewport) { 283 mFillViewport = fillViewport; 284 requestLayout(); 285 } 286 } 287 288 /** 289 * @return Whether arrow scrolling will animate its transition. 290 */ 291 public boolean isSmoothScrollingEnabled() { 292 return mSmoothScrollingEnabled; 293 } 294 295 /** 296 * Set whether arrow scrolling will animate its transition. 297 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 298 */ 299 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 300 mSmoothScrollingEnabled = smoothScrollingEnabled; 301 } 302 303 @Override 304 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 305 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 306 307 if (!mFillViewport) { 308 return; 309 } 310 311 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 312 if (widthMode == MeasureSpec.UNSPECIFIED) { 313 return; 314 } 315 316 if (getChildCount() > 0) { 317 final View child = getChildAt(0); 318 int width = getMeasuredWidth(); 319 if (child.getMeasuredWidth() < width) { 320 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 321 322 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 323 + mPaddingBottom, lp.height); 324 width -= mPaddingLeft; 325 width -= mPaddingRight; 326 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 327 328 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 329 } 330 } 331 } 332 333 @Override 334 public boolean dispatchKeyEvent(KeyEvent event) { 335 // Let the focused view and/or our descendants get the key first 336 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 337 } 338 339 /** 340 * You can call this function yourself to have the scroll view perform 341 * scrolling from a key event, just as if the event had been dispatched to 342 * it by the view hierarchy. 343 * 344 * @param event The key event to execute. 345 * @return Return true if the event was handled, else false. 346 */ 347 public boolean executeKeyEvent(KeyEvent event) { 348 mTempRect.setEmpty(); 349 350 if (!canScroll()) { 351 if (isFocused()) { 352 View currentFocused = findFocus(); 353 if (currentFocused == this) currentFocused = null; 354 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 355 currentFocused, View.FOCUS_RIGHT); 356 return nextFocused != null && nextFocused != this && 357 nextFocused.requestFocus(View.FOCUS_RIGHT); 358 } 359 return false; 360 } 361 362 boolean handled = false; 363 if (event.getAction() == KeyEvent.ACTION_DOWN) { 364 switch (event.getKeyCode()) { 365 case KeyEvent.KEYCODE_DPAD_LEFT: 366 if (!event.isAltPressed()) { 367 handled = arrowScroll(View.FOCUS_LEFT); 368 } else { 369 handled = fullScroll(View.FOCUS_LEFT); 370 } 371 break; 372 case KeyEvent.KEYCODE_DPAD_RIGHT: 373 if (!event.isAltPressed()) { 374 handled = arrowScroll(View.FOCUS_RIGHT); 375 } else { 376 handled = fullScroll(View.FOCUS_RIGHT); 377 } 378 break; 379 case KeyEvent.KEYCODE_SPACE: 380 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 381 break; 382 } 383 } 384 385 return handled; 386 } 387 388 private boolean inChild(int x, int y) { 389 if (getChildCount() > 0) { 390 final int scrollX = mScrollX; 391 final View child = getChildAt(0); 392 return !(y < child.getTop() 393 || y >= child.getBottom() 394 || x < child.getLeft() - scrollX 395 || x >= child.getRight() - scrollX); 396 } 397 return false; 398 } 399 400 @Override 401 public boolean onInterceptTouchEvent(MotionEvent ev) { 402 /* 403 * This method JUST determines whether we want to intercept the motion. 404 * If we return true, onMotionEvent will be called and we do the actual 405 * scrolling there. 406 */ 407 408 /* 409 * Shortcut the most recurring case: the user is in the dragging 410 * state and he is moving his finger. We want to intercept this 411 * motion. 412 */ 413 final int action = ev.getAction(); 414 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 415 return true; 416 } 417 418 switch (action & MotionEvent.ACTION_MASK) { 419 case MotionEvent.ACTION_MOVE: { 420 /* 421 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 422 * whether the user has moved far enough from his original down touch. 423 */ 424 425 /* 426 * Locally do absolute value. mLastMotionX is set to the x value 427 * of the down event. 428 */ 429 final int activePointerId = mActivePointerId; 430 if (activePointerId == INVALID_POINTER) { 431 // If we don't have a valid id, the touch down wasn't on content. 432 break; 433 } 434 435 final int pointerIndex = ev.findPointerIndex(activePointerId); 436 final float x = ev.getX(pointerIndex); 437 final int xDiff = (int) Math.abs(x - mLastMotionX); 438 if (xDiff > mTouchSlop) { 439 mIsBeingDragged = true; 440 mLastMotionX = x; 441 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 442 } 443 break; 444 } 445 446 case MotionEvent.ACTION_DOWN: { 447 final float x = ev.getX(); 448 if (!inChild((int) x, (int) ev.getY())) { 449 mIsBeingDragged = false; 450 break; 451 } 452 453 /* 454 * Remember location of down touch. 455 * ACTION_DOWN always refers to pointer index 0. 456 */ 457 mLastMotionX = x; 458 mActivePointerId = ev.getPointerId(0); 459 460 /* 461 * If being flinged and user touches the screen, initiate drag; 462 * otherwise don't. mScroller.isFinished should be false when 463 * being flinged. 464 */ 465 mIsBeingDragged = !mScroller.isFinished(); 466 break; 467 } 468 469 case MotionEvent.ACTION_CANCEL: 470 case MotionEvent.ACTION_UP: 471 /* Release the drag */ 472 mIsBeingDragged = false; 473 mActivePointerId = INVALID_POINTER; 474 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 475 invalidate(); 476 } 477 break; 478 case MotionEvent.ACTION_POINTER_DOWN: { 479 final int index = ev.getActionIndex(); 480 final float x = ev.getX(index); 481 mLastMotionX = x; 482 mActivePointerId = ev.getPointerId(index); 483 break; 484 } 485 case MotionEvent.ACTION_POINTER_UP: 486 onSecondaryPointerUp(ev); 487 mLastMotionX = ev.getX(ev.findPointerIndex(mActivePointerId)); 488 break; 489 } 490 491 /* 492 * The only time we want to intercept motion events is if we are in the 493 * drag mode. 494 */ 495 return mIsBeingDragged; 496 } 497 498 @Override 499 public boolean onTouchEvent(MotionEvent ev) { 500 501 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 502 // Don't handle edge touches immediately -- they may actually belong to one of our 503 // descendants. 504 return false; 505 } 506 507 if (mVelocityTracker == null) { 508 mVelocityTracker = VelocityTracker.obtain(); 509 } 510 mVelocityTracker.addMovement(ev); 511 512 final int action = ev.getAction(); 513 514 switch (action & MotionEvent.ACTION_MASK) { 515 case MotionEvent.ACTION_DOWN: { 516 mIsBeingDragged = getChildCount() != 0; 517 if (!mIsBeingDragged) { 518 return false; 519 } 520 521 /* 522 * If being flinged and user touches, stop the fling. isFinished 523 * will be false if being flinged. 524 */ 525 if (!mScroller.isFinished()) { 526 mScroller.abortAnimation(); 527 } 528 529 // Remember where the motion event started 530 mLastMotionX = ev.getX(); 531 mActivePointerId = ev.getPointerId(0); 532 break; 533 } 534 case MotionEvent.ACTION_MOVE: 535 if (mIsBeingDragged) { 536 // Scroll to follow the motion event 537 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 538 final float x = ev.getX(activePointerIndex); 539 final int deltaX = (int) (mLastMotionX - x); 540 mLastMotionX = x; 541 542 final int oldX = mScrollX; 543 final int oldY = mScrollY; 544 final int range = getScrollRange(); 545 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 546 mOverscrollDistance, 0, true)) { 547 // Break our velocity if we hit a scroll barrier. 548 mVelocityTracker.clear(); 549 } 550 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 551 552 final int overscrollMode = getOverScrollMode(); 553 if (overscrollMode == OVER_SCROLL_ALWAYS || 554 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 555 final int pulledToX = oldX + deltaX; 556 if (pulledToX < 0) { 557 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 558 if (!mEdgeGlowRight.isFinished()) { 559 mEdgeGlowRight.onRelease(); 560 } 561 } else if (pulledToX > range) { 562 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 563 if (!mEdgeGlowLeft.isFinished()) { 564 mEdgeGlowLeft.onRelease(); 565 } 566 } 567 if (mEdgeGlowLeft != null 568 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 569 invalidate(); 570 } 571 } 572 } 573 break; 574 case MotionEvent.ACTION_UP: 575 if (mIsBeingDragged) { 576 final VelocityTracker velocityTracker = mVelocityTracker; 577 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 578 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 579 580 if (getChildCount() > 0) { 581 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 582 fling(-initialVelocity); 583 } else { 584 final int right = getScrollRange(); 585 if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { 586 invalidate(); 587 } 588 } 589 } 590 591 mActivePointerId = INVALID_POINTER; 592 mIsBeingDragged = false; 593 594 if (mVelocityTracker != null) { 595 mVelocityTracker.recycle(); 596 mVelocityTracker = null; 597 } 598 if (mEdgeGlowLeft != null) { 599 mEdgeGlowLeft.onRelease(); 600 mEdgeGlowRight.onRelease(); 601 } 602 } 603 break; 604 case MotionEvent.ACTION_CANCEL: 605 if (mIsBeingDragged && getChildCount() > 0) { 606 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 607 invalidate(); 608 } 609 mActivePointerId = INVALID_POINTER; 610 mIsBeingDragged = false; 611 if (mVelocityTracker != null) { 612 mVelocityTracker.recycle(); 613 mVelocityTracker = null; 614 } 615 if (mEdgeGlowLeft != null) { 616 mEdgeGlowLeft.onRelease(); 617 mEdgeGlowRight.onRelease(); 618 } 619 } 620 break; 621 case MotionEvent.ACTION_POINTER_UP: 622 onSecondaryPointerUp(ev); 623 break; 624 } 625 return true; 626 } 627 628 private void onSecondaryPointerUp(MotionEvent ev) { 629 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 630 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 631 final int pointerId = ev.getPointerId(pointerIndex); 632 if (pointerId == mActivePointerId) { 633 // This was our active pointer going up. Choose a new 634 // active pointer and adjust accordingly. 635 // TODO: Make this decision more intelligent. 636 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 637 mLastMotionX = ev.getX(newPointerIndex); 638 mActivePointerId = ev.getPointerId(newPointerIndex); 639 if (mVelocityTracker != null) { 640 mVelocityTracker.clear(); 641 } 642 } 643 } 644 645 @Override 646 public boolean onGenericMotionEvent(MotionEvent event) { 647 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 648 switch (event.getAction()) { 649 case MotionEvent.ACTION_SCROLL: { 650 if (!mIsBeingDragged) { 651 final float hscroll; 652 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 653 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 654 } else { 655 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 656 } 657 if (hscroll != 0) { 658 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 659 final int range = getScrollRange(); 660 int oldScrollX = mScrollX; 661 int newScrollX = oldScrollX + delta; 662 if (newScrollX < 0) { 663 newScrollX = 0; 664 } else if (newScrollX > range) { 665 newScrollX = range; 666 } 667 if (newScrollX != oldScrollX) { 668 super.scrollTo(newScrollX, mScrollY); 669 return true; 670 } 671 } 672 } 673 } 674 } 675 } 676 return super.onGenericMotionEvent(event); 677 } 678 679 @Override 680 protected void onOverScrolled(int scrollX, int scrollY, 681 boolean clampedX, boolean clampedY) { 682 // Treat animating scrolls differently; see #computeScroll() for why. 683 if (!mScroller.isFinished()) { 684 mScrollX = scrollX; 685 mScrollY = scrollY; 686 invalidateParentIfNeeded(); 687 if (clampedX) { 688 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 689 } 690 } else { 691 super.scrollTo(scrollX, scrollY); 692 } 693 awakenScrollBars(); 694 } 695 696 private int getScrollRange() { 697 int scrollRange = 0; 698 if (getChildCount() > 0) { 699 View child = getChildAt(0); 700 scrollRange = Math.max(0, 701 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 702 } 703 return scrollRange; 704 } 705 706 /** 707 * <p> 708 * Finds the next focusable component that fits in this View's bounds 709 * (excluding fading edges) pretending that this View's left is located at 710 * the parameter left. 711 * </p> 712 * 713 * @param leftFocus look for a candidate is the one at the left of the bounds 714 * if leftFocus is true, or at the right of the bounds if leftFocus 715 * is false 716 * @param left the left offset of the bounds in which a focusable must be 717 * found (the fading edge is assumed to start at this position) 718 * @param preferredFocusable the View that has highest priority and will be 719 * returned if it is within my bounds (null is valid) 720 * @return the next focusable component in the bounds or null if none can be found 721 */ 722 private View findFocusableViewInMyBounds(final boolean leftFocus, 723 final int left, View preferredFocusable) { 724 /* 725 * The fading edge's transparent side should be considered for focus 726 * since it's mostly visible, so we divide the actual fading edge length 727 * by 2. 728 */ 729 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 730 final int leftWithoutFadingEdge = left + fadingEdgeLength; 731 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 732 733 if ((preferredFocusable != null) 734 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 735 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 736 return preferredFocusable; 737 } 738 739 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 740 rightWithoutFadingEdge); 741 } 742 743 /** 744 * <p> 745 * Finds the next focusable component that fits in the specified bounds. 746 * </p> 747 * 748 * @param leftFocus look for a candidate is the one at the left of the bounds 749 * if leftFocus is true, or at the right of the bounds if 750 * leftFocus is false 751 * @param left the left offset of the bounds in which a focusable must be 752 * found 753 * @param right the right offset of the bounds in which a focusable must 754 * be found 755 * @return the next focusable component in the bounds or null if none can 756 * be found 757 */ 758 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 759 760 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 761 View focusCandidate = null; 762 763 /* 764 * A fully contained focusable is one where its left is below the bound's 765 * left, and its right is above the bound's right. A partially 766 * contained focusable is one where some part of it is within the 767 * bounds, but it also has some part that is not within bounds. A fully contained 768 * focusable is preferred to a partially contained focusable. 769 */ 770 boolean foundFullyContainedFocusable = false; 771 772 int count = focusables.size(); 773 for (int i = 0; i < count; i++) { 774 View view = focusables.get(i); 775 int viewLeft = view.getLeft(); 776 int viewRight = view.getRight(); 777 778 if (left < viewRight && viewLeft < right) { 779 /* 780 * the focusable is in the target area, it is a candidate for 781 * focusing 782 */ 783 784 final boolean viewIsFullyContained = (left < viewLeft) && 785 (viewRight < right); 786 787 if (focusCandidate == null) { 788 /* No candidate, take this one */ 789 focusCandidate = view; 790 foundFullyContainedFocusable = viewIsFullyContained; 791 } else { 792 final boolean viewIsCloserToBoundary = 793 (leftFocus && viewLeft < focusCandidate.getLeft()) || 794 (!leftFocus && viewRight > focusCandidate.getRight()); 795 796 if (foundFullyContainedFocusable) { 797 if (viewIsFullyContained && viewIsCloserToBoundary) { 798 /* 799 * We're dealing with only fully contained views, so 800 * it has to be closer to the boundary to beat our 801 * candidate 802 */ 803 focusCandidate = view; 804 } 805 } else { 806 if (viewIsFullyContained) { 807 /* Any fully contained view beats a partially contained view */ 808 focusCandidate = view; 809 foundFullyContainedFocusable = true; 810 } else if (viewIsCloserToBoundary) { 811 /* 812 * Partially contained view beats another partially 813 * contained view if it's closer 814 */ 815 focusCandidate = view; 816 } 817 } 818 } 819 } 820 } 821 822 return focusCandidate; 823 } 824 825 /** 826 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 827 * method will scroll the view by one page left or right and give the focus 828 * to the leftmost/rightmost component in the new visible area. If no 829 * component is a good candidate for focus, this scrollview reclaims the 830 * focus.</p> 831 * 832 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 833 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 834 * to go one page right 835 * @return true if the key event is consumed by this method, false otherwise 836 */ 837 public boolean pageScroll(int direction) { 838 boolean right = direction == View.FOCUS_RIGHT; 839 int width = getWidth(); 840 841 if (right) { 842 mTempRect.left = getScrollX() + width; 843 int count = getChildCount(); 844 if (count > 0) { 845 View view = getChildAt(0); 846 if (mTempRect.left + width > view.getRight()) { 847 mTempRect.left = view.getRight() - width; 848 } 849 } 850 } else { 851 mTempRect.left = getScrollX() - width; 852 if (mTempRect.left < 0) { 853 mTempRect.left = 0; 854 } 855 } 856 mTempRect.right = mTempRect.left + width; 857 858 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 859 } 860 861 /** 862 * <p>Handles scrolling in response to a "home/end" shortcut press. This 863 * method will scroll the view to the 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 the left of the view or {@link android.view.View#FOCUS_RIGHT} 870 * to go the right 871 * @return true if the key event is consumed by this method, false otherwise 872 */ 873 public boolean fullScroll(int direction) { 874 boolean right = direction == View.FOCUS_RIGHT; 875 int width = getWidth(); 876 877 mTempRect.left = 0; 878 mTempRect.right = width; 879 880 if (right) { 881 int count = getChildCount(); 882 if (count > 0) { 883 View view = getChildAt(0); 884 mTempRect.right = view.getRight(); 885 mTempRect.left = mTempRect.right - width; 886 } 887 } 888 889 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 890 } 891 892 /** 893 * <p>Scrolls the view to make the area defined by <code>left</code> and 894 * <code>right</code> visible. This method attempts to give the focus 895 * to a component visible in this area. If no component can be focused in 896 * the new visible area, the focus is reclaimed by this scrollview.</p> 897 * 898 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 899 * to go left {@link android.view.View#FOCUS_RIGHT} to right 900 * @param left the left offset of the new area to be made visible 901 * @param right the right offset of the new area to be made visible 902 * @return true if the key event is consumed by this method, false otherwise 903 */ 904 private boolean scrollAndFocus(int direction, int left, int right) { 905 boolean handled = true; 906 907 int width = getWidth(); 908 int containerLeft = getScrollX(); 909 int containerRight = containerLeft + width; 910 boolean goLeft = direction == View.FOCUS_LEFT; 911 912 View newFocused = findFocusableViewInBounds(goLeft, left, right); 913 if (newFocused == null) { 914 newFocused = this; 915 } 916 917 if (left >= containerLeft && right <= containerRight) { 918 handled = false; 919 } else { 920 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 921 doScrollX(delta); 922 } 923 924 if (newFocused != findFocus()) newFocused.requestFocus(direction); 925 926 return handled; 927 } 928 929 /** 930 * Handle scrolling in response to a left or right arrow click. 931 * 932 * @param direction The direction corresponding to the arrow key that was 933 * pressed 934 * @return True if we consumed the event, false otherwise 935 */ 936 public boolean arrowScroll(int direction) { 937 938 View currentFocused = findFocus(); 939 if (currentFocused == this) currentFocused = null; 940 941 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 942 943 final int maxJump = getMaxScrollAmount(); 944 945 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 946 nextFocused.getDrawingRect(mTempRect); 947 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 948 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 949 doScrollX(scrollDelta); 950 nextFocused.requestFocus(direction); 951 } else { 952 // no new focus 953 int scrollDelta = maxJump; 954 955 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 956 scrollDelta = getScrollX(); 957 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 958 959 int daRight = getChildAt(0).getRight(); 960 961 int screenRight = getScrollX() + getWidth(); 962 963 if (daRight - screenRight < maxJump) { 964 scrollDelta = daRight - screenRight; 965 } 966 } 967 if (scrollDelta == 0) { 968 return false; 969 } 970 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 971 } 972 973 if (currentFocused != null && currentFocused.isFocused() 974 && isOffScreen(currentFocused)) { 975 // previously focused item still has focus and is off screen, give 976 // it up (take it back to ourselves) 977 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 978 // sure to 979 // get it) 980 final int descendantFocusability = getDescendantFocusability(); // save 981 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 982 requestFocus(); 983 setDescendantFocusability(descendantFocusability); // restore 984 } 985 return true; 986 } 987 988 /** 989 * @return whether the descendant of this scroll view is scrolled off 990 * screen. 991 */ 992 private boolean isOffScreen(View descendant) { 993 return !isWithinDeltaOfScreen(descendant, 0); 994 } 995 996 /** 997 * @return whether the descendant of this scroll view is within delta 998 * pixels of being on the screen. 999 */ 1000 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1001 descendant.getDrawingRect(mTempRect); 1002 offsetDescendantRectToMyCoords(descendant, mTempRect); 1003 1004 return (mTempRect.right + delta) >= getScrollX() 1005 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1006 } 1007 1008 /** 1009 * Smooth scroll by a X delta 1010 * 1011 * @param delta the number of pixels to scroll by on the X axis 1012 */ 1013 private void doScrollX(int delta) { 1014 if (delta != 0) { 1015 if (mSmoothScrollingEnabled) { 1016 smoothScrollBy(delta, 0); 1017 } else { 1018 scrollBy(delta, 0); 1019 } 1020 } 1021 } 1022 1023 /** 1024 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1025 * 1026 * @param dx the number of pixels to scroll by on the X axis 1027 * @param dy the number of pixels to scroll by on the Y axis 1028 */ 1029 public final void smoothScrollBy(int dx, int dy) { 1030 if (getChildCount() == 0) { 1031 // Nothing to do. 1032 return; 1033 } 1034 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1035 if (duration > ANIMATED_SCROLL_GAP) { 1036 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1037 final int right = getChildAt(0).getWidth(); 1038 final int maxX = Math.max(0, right - width); 1039 final int scrollX = mScrollX; 1040 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1041 1042 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1043 invalidate(); 1044 } else { 1045 if (!mScroller.isFinished()) { 1046 mScroller.abortAnimation(); 1047 } 1048 scrollBy(dx, dy); 1049 } 1050 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1051 } 1052 1053 /** 1054 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1055 * 1056 * @param x the position where to scroll on the X axis 1057 * @param y the position where to scroll on the Y axis 1058 */ 1059 public final void smoothScrollTo(int x, int y) { 1060 smoothScrollBy(x - mScrollX, y - mScrollY); 1061 } 1062 1063 /** 1064 * <p>The scroll range of a scroll view is the overall width of all of its 1065 * children.</p> 1066 */ 1067 @Override 1068 protected int computeHorizontalScrollRange() { 1069 final int count = getChildCount(); 1070 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1071 if (count == 0) { 1072 return contentWidth; 1073 } 1074 1075 int scrollRange = getChildAt(0).getRight(); 1076 final int scrollX = mScrollX; 1077 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1078 if (scrollX < 0) { 1079 scrollRange -= scrollX; 1080 } else if (scrollX > overscrollRight) { 1081 scrollRange += scrollX - overscrollRight; 1082 } 1083 1084 return scrollRange; 1085 } 1086 1087 @Override 1088 protected int computeHorizontalScrollOffset() { 1089 return Math.max(0, super.computeHorizontalScrollOffset()); 1090 } 1091 1092 @Override 1093 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1094 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1095 1096 int childWidthMeasureSpec; 1097 int childHeightMeasureSpec; 1098 1099 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1100 + mPaddingBottom, lp.height); 1101 1102 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1103 1104 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1105 } 1106 1107 @Override 1108 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1109 int parentHeightMeasureSpec, int heightUsed) { 1110 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1111 1112 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1113 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1114 + heightUsed, lp.height); 1115 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1116 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1117 1118 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1119 } 1120 1121 @Override 1122 public void computeScroll() { 1123 if (mScroller.computeScrollOffset()) { 1124 // This is called at drawing time by ViewGroup. We don't want to 1125 // re-show the scrollbars at this point, which scrollTo will do, 1126 // so we replicate most of scrollTo here. 1127 // 1128 // It's a little odd to call onScrollChanged from inside the drawing. 1129 // 1130 // It is, except when you remember that computeScroll() is used to 1131 // animate scrolling. So unless we want to defer the onScrollChanged() 1132 // until the end of the animated scrolling, we don't really have a 1133 // choice here. 1134 // 1135 // I agree. The alternative, which I think would be worse, is to post 1136 // something and tell the subclasses later. This is bad because there 1137 // will be a window where mScrollX/Y is different from what the app 1138 // thinks it is. 1139 // 1140 int oldX = mScrollX; 1141 int oldY = mScrollY; 1142 int x = mScroller.getCurrX(); 1143 int y = mScroller.getCurrY(); 1144 1145 if (oldX != x || oldY != y) { 1146 overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, 1147 mOverflingDistance, 0, false); 1148 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1149 1150 final int range = getScrollRange(); 1151 final int overscrollMode = getOverScrollMode(); 1152 if (overscrollMode == OVER_SCROLL_ALWAYS || 1153 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1154 if (x < 0 && oldX >= 0) { 1155 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1156 } else if (x > range && oldX <= range) { 1157 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1158 } 1159 } 1160 } 1161 awakenScrollBars(); 1162 1163 // Keep on drawing until the animation has finished. 1164 postInvalidate(); 1165 } 1166 } 1167 1168 /** 1169 * Scrolls the view to the given child. 1170 * 1171 * @param child the View to scroll to 1172 */ 1173 private void scrollToChild(View child) { 1174 child.getDrawingRect(mTempRect); 1175 1176 /* Offset from child's local coordinates to ScrollView coordinates */ 1177 offsetDescendantRectToMyCoords(child, mTempRect); 1178 1179 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1180 1181 if (scrollDelta != 0) { 1182 scrollBy(scrollDelta, 0); 1183 } 1184 } 1185 1186 /** 1187 * If rect is off screen, scroll just enough to get it (or at least the 1188 * first screen size chunk of it) on screen. 1189 * 1190 * @param rect The rectangle. 1191 * @param immediate True to scroll immediately without animation 1192 * @return true if scrolling was performed 1193 */ 1194 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1195 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1196 final boolean scroll = delta != 0; 1197 if (scroll) { 1198 if (immediate) { 1199 scrollBy(delta, 0); 1200 } else { 1201 smoothScrollBy(delta, 0); 1202 } 1203 } 1204 return scroll; 1205 } 1206 1207 /** 1208 * Compute the amount to scroll in the X direction in order to get 1209 * a rectangle completely on the screen (or, if taller than the screen, 1210 * at least the first screen size chunk of it). 1211 * 1212 * @param rect The rect. 1213 * @return The scroll delta. 1214 */ 1215 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1216 if (getChildCount() == 0) return 0; 1217 1218 int width = getWidth(); 1219 int screenLeft = getScrollX(); 1220 int screenRight = screenLeft + width; 1221 1222 int fadingEdge = getHorizontalFadingEdgeLength(); 1223 1224 // leave room for left fading edge as long as rect isn't at very left 1225 if (rect.left > 0) { 1226 screenLeft += fadingEdge; 1227 } 1228 1229 // leave room for right fading edge as long as rect isn't at very right 1230 if (rect.right < getChildAt(0).getWidth()) { 1231 screenRight -= fadingEdge; 1232 } 1233 1234 int scrollXDelta = 0; 1235 1236 if (rect.right > screenRight && rect.left > screenLeft) { 1237 // need to move right to get it in view: move right just enough so 1238 // that the entire rectangle is in view (or at least the first 1239 // screen size chunk). 1240 1241 if (rect.width() > width) { 1242 // just enough to get screen size chunk on 1243 scrollXDelta += (rect.left - screenLeft); 1244 } else { 1245 // get entire rect at right of screen 1246 scrollXDelta += (rect.right - screenRight); 1247 } 1248 1249 // make sure we aren't scrolling beyond the end of our content 1250 int right = getChildAt(0).getRight(); 1251 int distanceToRight = right - screenRight; 1252 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1253 1254 } else if (rect.left < screenLeft && rect.right < screenRight) { 1255 // need to move right to get it in view: move right just enough so that 1256 // entire rectangle is in view (or at least the first screen 1257 // size chunk of it). 1258 1259 if (rect.width() > width) { 1260 // screen size chunk 1261 scrollXDelta -= (screenRight - rect.right); 1262 } else { 1263 // entire rect at left 1264 scrollXDelta -= (screenLeft - rect.left); 1265 } 1266 1267 // make sure we aren't scrolling any further than the left our content 1268 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1269 } 1270 return scrollXDelta; 1271 } 1272 1273 @Override 1274 public void requestChildFocus(View child, View focused) { 1275 if (!mIsLayoutDirty) { 1276 scrollToChild(focused); 1277 } else { 1278 // The child may not be laid out yet, we can't compute the scroll yet 1279 mChildToScrollTo = focused; 1280 } 1281 super.requestChildFocus(child, focused); 1282 } 1283 1284 1285 /** 1286 * When looking for focus in children of a scroll view, need to be a little 1287 * more careful not to give focus to something that is scrolled off screen. 1288 * 1289 * This is more expensive than the default {@link android.view.ViewGroup} 1290 * implementation, otherwise this behavior might have been made the default. 1291 */ 1292 @Override 1293 protected boolean onRequestFocusInDescendants(int direction, 1294 Rect previouslyFocusedRect) { 1295 1296 // convert from forward / backward notation to up / down / left / right 1297 // (ugh). 1298 if (direction == View.FOCUS_FORWARD) { 1299 direction = View.FOCUS_RIGHT; 1300 } else if (direction == View.FOCUS_BACKWARD) { 1301 direction = View.FOCUS_LEFT; 1302 } 1303 1304 final View nextFocus = previouslyFocusedRect == null ? 1305 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1306 FocusFinder.getInstance().findNextFocusFromRect(this, 1307 previouslyFocusedRect, direction); 1308 1309 if (nextFocus == null) { 1310 return false; 1311 } 1312 1313 if (isOffScreen(nextFocus)) { 1314 return false; 1315 } 1316 1317 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1318 } 1319 1320 @Override 1321 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1322 boolean immediate) { 1323 // offset into coordinate space of this scroll view 1324 rectangle.offset(child.getLeft() - child.getScrollX(), 1325 child.getTop() - child.getScrollY()); 1326 1327 return scrollToChildRect(rectangle, immediate); 1328 } 1329 1330 @Override 1331 public void requestLayout() { 1332 mIsLayoutDirty = true; 1333 super.requestLayout(); 1334 } 1335 1336 @Override 1337 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1338 super.onLayout(changed, l, t, r, b); 1339 mIsLayoutDirty = false; 1340 // Give a child focus if it needs it 1341 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1342 scrollToChild(mChildToScrollTo); 1343 } 1344 mChildToScrollTo = null; 1345 1346 // Calling this with the present values causes it to re-clam them 1347 scrollTo(mScrollX, mScrollY); 1348 } 1349 1350 @Override 1351 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1352 super.onSizeChanged(w, h, oldw, oldh); 1353 1354 View currentFocused = findFocus(); 1355 if (null == currentFocused || this == currentFocused) 1356 return; 1357 1358 final int maxJump = mRight - mLeft; 1359 1360 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1361 currentFocused.getDrawingRect(mTempRect); 1362 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1363 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1364 doScrollX(scrollDelta); 1365 } 1366 } 1367 1368 /** 1369 * Return true if child is an descendant of parent, (or equal to the parent). 1370 */ 1371 private boolean isViewDescendantOf(View child, View parent) { 1372 if (child == parent) { 1373 return true; 1374 } 1375 1376 final ViewParent theParent = child.getParent(); 1377 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1378 } 1379 1380 /** 1381 * Fling the scroll view 1382 * 1383 * @param velocityX The initial velocity in the X direction. Positive 1384 * numbers mean that the finger/curor is moving down the screen, 1385 * which means we want to scroll towards the left. 1386 */ 1387 public void fling(int velocityX) { 1388 if (getChildCount() > 0) { 1389 int width = getWidth() - mPaddingRight - mPaddingLeft; 1390 int right = getChildAt(0).getWidth(); 1391 1392 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1393 Math.max(0, right - width), 0, 0, width/2, 0); 1394 1395 final boolean movingRight = velocityX > 0; 1396 1397 View currentFocused = findFocus(); 1398 View newFocused = findFocusableViewInMyBounds(movingRight, 1399 mScroller.getFinalX(), currentFocused); 1400 1401 if (newFocused == null) { 1402 newFocused = this; 1403 } 1404 1405 if (newFocused != currentFocused) { 1406 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1407 } 1408 1409 invalidate(); 1410 } 1411 } 1412 1413 /** 1414 * {@inheritDoc} 1415 * 1416 * <p>This version also clamps the scrolling to the bounds of our child. 1417 */ 1418 @Override 1419 public void scrollTo(int x, int y) { 1420 // we rely on the fact the View.scrollBy calls scrollTo. 1421 if (getChildCount() > 0) { 1422 View child = getChildAt(0); 1423 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1424 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1425 if (x != mScrollX || y != mScrollY) { 1426 super.scrollTo(x, y); 1427 } 1428 } 1429 } 1430 1431 @Override 1432 public void setOverScrollMode(int mode) { 1433 if (mode != OVER_SCROLL_NEVER) { 1434 if (mEdgeGlowLeft == null) { 1435 Context context = getContext(); 1436 final Resources res = context.getResources(); 1437 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1438 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1439 mEdgeGlowLeft = new EdgeGlow(context, edge, glow); 1440 mEdgeGlowRight = new EdgeGlow(context, edge, glow); 1441 } 1442 } else { 1443 mEdgeGlowLeft = null; 1444 mEdgeGlowRight = null; 1445 } 1446 super.setOverScrollMode(mode); 1447 } 1448 1449 @Override 1450 public void draw(Canvas canvas) { 1451 super.draw(canvas); 1452 if (mEdgeGlowLeft != null) { 1453 final int scrollX = mScrollX; 1454 if (!mEdgeGlowLeft.isFinished()) { 1455 final int restoreCount = canvas.save(); 1456 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1457 1458 canvas.rotate(270); 1459 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1460 mEdgeGlowLeft.setSize(height, getWidth()); 1461 if (mEdgeGlowLeft.draw(canvas)) { 1462 invalidate(); 1463 } 1464 canvas.restoreToCount(restoreCount); 1465 } 1466 if (!mEdgeGlowRight.isFinished()) { 1467 final int restoreCount = canvas.save(); 1468 final int width = getWidth(); 1469 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1470 1471 canvas.rotate(90); 1472 canvas.translate(-mPaddingTop, 1473 -(Math.max(getScrollRange(), scrollX) + width)); 1474 mEdgeGlowRight.setSize(height, width); 1475 if (mEdgeGlowRight.draw(canvas)) { 1476 invalidate(); 1477 } 1478 canvas.restoreToCount(restoreCount); 1479 } 1480 } 1481 } 1482 1483 private int clamp(int n, int my, int child) { 1484 if (my >= child || n < 0) { 1485 return 0; 1486 } 1487 if ((my + n) > child) { 1488 return child - my; 1489 } 1490 return n; 1491 } 1492} 1493