ScrollView.java revision e6ffce9f65a1a8f498eb51a993a8cbf5f13a109e
1/* 2 * Copyright (C) 2006 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.KeyEvent; 30import android.view.MotionEvent; 31import android.view.VelocityTracker; 32import android.view.View; 33import android.view.ViewConfiguration; 34import android.view.ViewGroup; 35import android.view.ViewParent; 36import android.view.animation.AnimationUtils; 37 38import 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 ScrollView 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 vertical orientation, presenting a vertical 47 * array of top-level items that the user can scroll through. 48 * 49 * <p>The {@link TextView} class also 50 * takes care of its own scrolling, so does not require a ScrollView, but 51 * using the two together is possible to achieve the effect of a text view 52 * within a larger container. 53 * 54 * <p>ScrollView only supports vertical scrolling. 55 */ 56public class ScrollView extends FrameLayout { 57 static final int ANIMATED_SCROLL_GAP = 250; 58 59 static final float MAX_SCROLL_FACTOR = 0.5f; 60 61 62 private long mLastScroll; 63 64 private final Rect mTempRect = new Rect(); 65 private OverScroller mScroller; 66 private EdgeGlow mEdgeGlowTop; 67 private EdgeGlow mEdgeGlowBottom; 68 69 /** 70 * Flag to indicate that we are moving focus ourselves. This is so the 71 * code that watches for focus changes initiated outside this ScrollView 72 * knows that it does not have to do anything. 73 */ 74 private boolean mScrollViewMovedFocus; 75 76 /** 77 * Position of the last motion event. 78 */ 79 private float mLastMotionY; 80 81 /** 82 * True when the layout has changed but the traversal has not come through yet. 83 * Ideally the view hierarchy would keep track of this for us. 84 */ 85 private boolean mIsLayoutDirty = true; 86 87 /** 88 * The child to give focus to in the event that a child has requested focus while the 89 * layout is dirty. This prevents the scroll from being wrong if the child has not been 90 * laid out before requesting focus. 91 */ 92 private View mChildToScrollTo = null; 93 94 /** 95 * True if the user is currently dragging this ScrollView around. This is 96 * not the same as 'is being flinged', which can be checked by 97 * mScroller.isFinished() (flinging begins when the user lifts his finger). 98 */ 99 private boolean mIsBeingDragged = false; 100 101 /** 102 * Determines speed during touch scrolling 103 */ 104 private VelocityTracker mVelocityTracker; 105 106 /** 107 * When set to true, the scroll view measure its child to make it fill the currently 108 * visible area. 109 */ 110 private boolean mFillViewport; 111 112 /** 113 * Whether arrow scrolling is animated. 114 */ 115 private boolean mSmoothScrollingEnabled = true; 116 117 private int mTouchSlop; 118 private int mMinimumVelocity; 119 private int mMaximumVelocity; 120 121 private int mOverscrollDistance; 122 private int mOverflingDistance; 123 124 /** 125 * ID of the active pointer. This is used to retain consistency during 126 * drags/flings if multiple pointers are used. 127 */ 128 private int mActivePointerId = INVALID_POINTER; 129 130 /** 131 * Sentinel value for no current active pointer. 132 * Used by {@link #mActivePointerId}. 133 */ 134 private static final int INVALID_POINTER = -1; 135 136 public ScrollView(Context context) { 137 this(context, null); 138 } 139 140 public ScrollView(Context context, AttributeSet attrs) { 141 this(context, attrs, com.android.internal.R.attr.scrollViewStyle); 142 } 143 144 public ScrollView(Context context, AttributeSet attrs, int defStyle) { 145 super(context, attrs, defStyle); 146 initScrollView(); 147 148 TypedArray a = 149 context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ScrollView, defStyle, 0); 150 151 setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false)); 152 153 a.recycle(); 154 } 155 156 @Override 157 protected float getTopFadingEdgeStrength() { 158 if (getChildCount() == 0) { 159 return 0.0f; 160 } 161 162 final int length = getVerticalFadingEdgeLength(); 163 if (mScrollY < length) { 164 return mScrollY / (float) length; 165 } 166 167 return 1.0f; 168 } 169 170 @Override 171 protected float getBottomFadingEdgeStrength() { 172 if (getChildCount() == 0) { 173 return 0.0f; 174 } 175 176 final int length = getVerticalFadingEdgeLength(); 177 final int bottomEdge = getHeight() - mPaddingBottom; 178 final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge; 179 if (span < length) { 180 return span / (float) length; 181 } 182 183 return 1.0f; 184 } 185 186 /** 187 * @return The maximum amount this scroll view will scroll in response to 188 * an arrow event. 189 */ 190 public int getMaxScrollAmount() { 191 return (int) (MAX_SCROLL_FACTOR * (mBottom - mTop)); 192 } 193 194 195 private void initScrollView() { 196 mScroller = new OverScroller(getContext()); 197 setFocusable(true); 198 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 199 setWillNotDraw(false); 200 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 201 mTouchSlop = configuration.getScaledTouchSlop(); 202 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 203 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 204 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 205 mOverflingDistance = configuration.getScaledOverflingDistance(); 206 } 207 208 @Override 209 public void addView(View child) { 210 if (getChildCount() > 0) { 211 throw new IllegalStateException("ScrollView can host only one direct child"); 212 } 213 214 super.addView(child); 215 } 216 217 @Override 218 public void addView(View child, int index) { 219 if (getChildCount() > 0) { 220 throw new IllegalStateException("ScrollView can host only one direct child"); 221 } 222 223 super.addView(child, index); 224 } 225 226 @Override 227 public void addView(View child, ViewGroup.LayoutParams params) { 228 if (getChildCount() > 0) { 229 throw new IllegalStateException("ScrollView can host only one direct child"); 230 } 231 232 super.addView(child, params); 233 } 234 235 @Override 236 public void addView(View child, int index, ViewGroup.LayoutParams params) { 237 if (getChildCount() > 0) { 238 throw new IllegalStateException("ScrollView can host only one direct child"); 239 } 240 241 super.addView(child, index, params); 242 } 243 244 /** 245 * @return Returns true this ScrollView can be scrolled 246 */ 247 private boolean canScroll() { 248 View child = getChildAt(0); 249 if (child != null) { 250 int childHeight = child.getHeight(); 251 return getHeight() < childHeight + mPaddingTop + mPaddingBottom; 252 } 253 return false; 254 } 255 256 /** 257 * Indicates whether this ScrollView's content is stretched to fill the viewport. 258 * 259 * @return True if the content fills the viewport, false otherwise. 260 */ 261 public boolean isFillViewport() { 262 return mFillViewport; 263 } 264 265 /** 266 * Indicates this ScrollView whether it should stretch its content height to fill 267 * the viewport or not. 268 * 269 * @param fillViewport True to stretch the content's height to the viewport's 270 * boundaries, false otherwise. 271 */ 272 public void setFillViewport(boolean fillViewport) { 273 if (fillViewport != mFillViewport) { 274 mFillViewport = fillViewport; 275 requestLayout(); 276 } 277 } 278 279 /** 280 * @return Whether arrow scrolling will animate its transition. 281 */ 282 public boolean isSmoothScrollingEnabled() { 283 return mSmoothScrollingEnabled; 284 } 285 286 /** 287 * Set whether arrow scrolling will animate its transition. 288 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 289 */ 290 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 291 mSmoothScrollingEnabled = smoothScrollingEnabled; 292 } 293 294 @Override 295 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 296 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 297 298 if (!mFillViewport) { 299 return; 300 } 301 302 final int heightMode = MeasureSpec.getMode(heightMeasureSpec); 303 if (heightMode == MeasureSpec.UNSPECIFIED) { 304 return; 305 } 306 307 if (getChildCount() > 0) { 308 final View child = getChildAt(0); 309 int height = getMeasuredHeight(); 310 if (child.getMeasuredHeight() < height) { 311 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 312 313 int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, mPaddingLeft 314 + mPaddingRight, lp.width); 315 height -= mPaddingTop; 316 height -= mPaddingBottom; 317 int childHeightMeasureSpec = 318 MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); 319 320 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 321 } 322 } 323 } 324 325 @Override 326 public boolean dispatchKeyEvent(KeyEvent event) { 327 // Let the focused view and/or our descendants get the key first 328 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 329 } 330 331 /** 332 * You can call this function yourself to have the scroll view perform 333 * scrolling from a key event, just as if the event had been dispatched to 334 * it by the view hierarchy. 335 * 336 * @param event The key event to execute. 337 * @return Return true if the event was handled, else false. 338 */ 339 public boolean executeKeyEvent(KeyEvent event) { 340 mTempRect.setEmpty(); 341 342 if (!canScroll()) { 343 if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { 344 View currentFocused = findFocus(); 345 if (currentFocused == this) currentFocused = null; 346 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 347 currentFocused, View.FOCUS_DOWN); 348 return nextFocused != null 349 && nextFocused != this 350 && nextFocused.requestFocus(View.FOCUS_DOWN); 351 } 352 return false; 353 } 354 355 boolean handled = false; 356 if (event.getAction() == KeyEvent.ACTION_DOWN) { 357 switch (event.getKeyCode()) { 358 case KeyEvent.KEYCODE_DPAD_UP: 359 if (!event.isAltPressed()) { 360 handled = arrowScroll(View.FOCUS_UP); 361 } else { 362 handled = fullScroll(View.FOCUS_UP); 363 } 364 break; 365 case KeyEvent.KEYCODE_DPAD_DOWN: 366 if (!event.isAltPressed()) { 367 handled = arrowScroll(View.FOCUS_DOWN); 368 } else { 369 handled = fullScroll(View.FOCUS_DOWN); 370 } 371 break; 372 case KeyEvent.KEYCODE_SPACE: 373 pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); 374 break; 375 } 376 } 377 378 return handled; 379 } 380 381 private boolean inChild(int x, int y) { 382 if (getChildCount() > 0) { 383 final int scrollY = mScrollY; 384 final View child = getChildAt(0); 385 return !(y < child.getTop() - scrollY 386 || y >= child.getBottom() - scrollY 387 || x < child.getLeft() 388 || x >= child.getRight()); 389 } 390 return false; 391 } 392 393 @Override 394 public boolean onInterceptTouchEvent(MotionEvent ev) { 395 /* 396 * This method JUST determines whether we want to intercept the motion. 397 * If we return true, onMotionEvent will be called and we do the actual 398 * scrolling there. 399 */ 400 401 /* 402 * Shortcut the most recurring case: the user is in the dragging 403 * state and he is moving his finger. We want to intercept this 404 * motion. 405 */ 406 final int action = ev.getAction(); 407 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 408 return true; 409 } 410 411 switch (action & MotionEvent.ACTION_MASK) { 412 case MotionEvent.ACTION_MOVE: { 413 /* 414 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 415 * whether the user has moved far enough from his original down touch. 416 */ 417 418 /* 419 * Locally do absolute value. mLastMotionY is set to the y value 420 * of the down event. 421 */ 422 final int activePointerId = mActivePointerId; 423 if (activePointerId == INVALID_POINTER) { 424 // If we don't have a valid id, the touch down wasn't on content. 425 break; 426 } 427 428 final int pointerIndex = ev.findPointerIndex(activePointerId); 429 final float y = ev.getY(pointerIndex); 430 final int yDiff = (int) Math.abs(y - mLastMotionY); 431 if (yDiff > mTouchSlop) { 432 mIsBeingDragged = true; 433 mLastMotionY = y; 434 } 435 break; 436 } 437 438 case MotionEvent.ACTION_DOWN: { 439 final float y = ev.getY(); 440 if (!inChild((int) ev.getX(), (int) y)) { 441 mIsBeingDragged = false; 442 break; 443 } 444 445 /* 446 * Remember location of down touch. 447 * ACTION_DOWN always refers to pointer index 0. 448 */ 449 mLastMotionY = y; 450 mActivePointerId = ev.getPointerId(0); 451 452 /* 453 * If being flinged and user touches the screen, initiate drag; 454 * otherwise don't. mScroller.isFinished should be false when 455 * being flinged. 456 */ 457 mIsBeingDragged = !mScroller.isFinished(); 458 break; 459 } 460 461 case MotionEvent.ACTION_CANCEL: 462 case MotionEvent.ACTION_UP: 463 /* Release the drag */ 464 mIsBeingDragged = false; 465 mActivePointerId = INVALID_POINTER; 466 if (mScroller.springback(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 467 invalidate(); 468 } 469 break; 470 case MotionEvent.ACTION_POINTER_UP: 471 onSecondaryPointerUp(ev); 472 break; 473 } 474 475 /* 476 * The only time we want to intercept motion events is if we are in the 477 * drag mode. 478 */ 479 return mIsBeingDragged; 480 } 481 482 @Override 483 public boolean onTouchEvent(MotionEvent ev) { 484 485 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 486 // Don't handle edge touches immediately -- they may actually belong to one of our 487 // descendants. 488 return false; 489 } 490 491 if (mVelocityTracker == null) { 492 mVelocityTracker = VelocityTracker.obtain(); 493 } 494 mVelocityTracker.addMovement(ev); 495 496 final int action = ev.getAction(); 497 498 switch (action & MotionEvent.ACTION_MASK) { 499 case MotionEvent.ACTION_DOWN: { 500 final float y = ev.getY(); 501 if (!(mIsBeingDragged = inChild((int) ev.getX(), (int) y))) { 502 return false; 503 } 504 505 /* 506 * If being flinged and user touches, stop the fling. isFinished 507 * will be false if being flinged. 508 */ 509 if (!mScroller.isFinished()) { 510 mScroller.abortAnimation(); 511 } 512 513 // Remember where the motion event started 514 mLastMotionY = y; 515 mActivePointerId = ev.getPointerId(0); 516 break; 517 } 518 case MotionEvent.ACTION_MOVE: 519 if (mIsBeingDragged) { 520 // Scroll to follow the motion event 521 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 522 final float y = ev.getY(activePointerIndex); 523 final int deltaY = (int) (mLastMotionY - y); 524 mLastMotionY = y; 525 526 final int oldX = mScrollX; 527 final int oldY = mScrollY; 528 final int range = getScrollRange(); 529 if (overscrollBy(0, deltaY, 0, mScrollY, 0, range, 530 0, mOverscrollDistance, true)) { 531 // Break our velocity if we hit a scroll barrier. 532 mVelocityTracker.clear(); 533 } 534 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 535 536 final int overscrollMode = getOverscrollMode(); 537 if (overscrollMode == OVERSCROLL_ALWAYS || 538 (overscrollMode == OVERSCROLL_IF_CONTENT_SCROLLS && range > 0)) { 539 final int pulledToY = oldY + deltaY; 540 if (pulledToY < 0) { 541 mEdgeGlowTop.onPull((float) deltaY / getHeight()); 542 } else if (pulledToY > range) { 543 mEdgeGlowBottom.onPull((float) deltaY / getHeight()); 544 } 545 } 546 } 547 break; 548 case MotionEvent.ACTION_UP: 549 if (mIsBeingDragged) { 550 final VelocityTracker velocityTracker = mVelocityTracker; 551 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 552 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 553 554 if (getChildCount() > 0) { 555 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 556 fling(-initialVelocity); 557 } else { 558 final int bottom = getScrollRange(); 559 if (mScroller.springback(mScrollX, mScrollY, 0, 0, 0, bottom)) { 560 invalidate(); 561 } 562 } 563 } 564 565 mActivePointerId = INVALID_POINTER; 566 mIsBeingDragged = false; 567 568 if (mVelocityTracker != null) { 569 mVelocityTracker.recycle(); 570 mVelocityTracker = null; 571 } 572 if (mEdgeGlowTop != null) { 573 mEdgeGlowTop.onRelease(); 574 mEdgeGlowBottom.onRelease(); 575 } 576 } 577 break; 578 case MotionEvent.ACTION_CANCEL: 579 if (mIsBeingDragged && getChildCount() > 0) { 580 if (mScroller.springback(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 581 invalidate(); 582 } 583 mActivePointerId = INVALID_POINTER; 584 mIsBeingDragged = false; 585 if (mVelocityTracker != null) { 586 mVelocityTracker.recycle(); 587 mVelocityTracker = null; 588 } 589 if (mEdgeGlowTop != null) { 590 mEdgeGlowTop.onRelease(); 591 mEdgeGlowBottom.onRelease(); 592 } 593 } 594 break; 595 case MotionEvent.ACTION_POINTER_UP: 596 onSecondaryPointerUp(ev); 597 break; 598 } 599 return true; 600 } 601 602 private void onSecondaryPointerUp(MotionEvent ev) { 603 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 604 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 605 final int pointerId = ev.getPointerId(pointerIndex); 606 if (pointerId == mActivePointerId) { 607 // This was our active pointer going up. Choose a new 608 // active pointer and adjust accordingly. 609 // TODO: Make this decision more intelligent. 610 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 611 mLastMotionY = ev.getY(newPointerIndex); 612 mActivePointerId = ev.getPointerId(newPointerIndex); 613 if (mVelocityTracker != null) { 614 mVelocityTracker.clear(); 615 } 616 } 617 } 618 619 @Override 620 protected void onOverscrolled(int scrollX, int scrollY, 621 boolean clampedX, boolean clampedY) { 622 // Treat animating scrolls differently; see #computeScroll() for why. 623 if (!mScroller.isFinished()) { 624 mScrollX = scrollX; 625 mScrollY = scrollY; 626 if (clampedY) { 627 mScroller.springback(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 628 } 629 } else { 630 super.scrollTo(scrollX, scrollY); 631 } 632 awakenScrollBars(); 633 } 634 635 private int getScrollRange() { 636 int scrollRange = 0; 637 if (getChildCount() > 0) { 638 View child = getChildAt(0); 639 scrollRange = Math.max(0, 640 child.getHeight() - getHeight() - mPaddingBottom - mPaddingTop); 641 } 642 return scrollRange; 643 } 644 645 /** 646 * <p> 647 * Finds the next focusable component that fits in this View's bounds 648 * (excluding fading edges) pretending that this View's top is located at 649 * the parameter top. 650 * </p> 651 * 652 * @param topFocus look for a candidate is the one at the top of the bounds 653 * if topFocus is true, or at the bottom of the bounds if topFocus is 654 * false 655 * @param top the top offset of the bounds in which a focusable must be 656 * found (the fading edge is assumed to start at this position) 657 * @param preferredFocusable the View that has highest priority and will be 658 * returned if it is within my bounds (null is valid) 659 * @return the next focusable component in the bounds or null if none can be 660 * found 661 */ 662 private View findFocusableViewInMyBounds(final boolean topFocus, 663 final int top, View preferredFocusable) { 664 /* 665 * The fading edge's transparent side should be considered for focus 666 * since it's mostly visible, so we divide the actual fading edge length 667 * by 2. 668 */ 669 final int fadingEdgeLength = getVerticalFadingEdgeLength() / 2; 670 final int topWithoutFadingEdge = top + fadingEdgeLength; 671 final int bottomWithoutFadingEdge = top + getHeight() - fadingEdgeLength; 672 673 if ((preferredFocusable != null) 674 && (preferredFocusable.getTop() < bottomWithoutFadingEdge) 675 && (preferredFocusable.getBottom() > topWithoutFadingEdge)) { 676 return preferredFocusable; 677 } 678 679 return findFocusableViewInBounds(topFocus, topWithoutFadingEdge, 680 bottomWithoutFadingEdge); 681 } 682 683 /** 684 * <p> 685 * Finds the next focusable component that fits in the specified bounds. 686 * </p> 687 * 688 * @param topFocus look for a candidate is the one at the top of the bounds 689 * if topFocus is true, or at the bottom of the bounds if topFocus is 690 * false 691 * @param top the top offset of the bounds in which a focusable must be 692 * found 693 * @param bottom the bottom offset of the bounds in which a focusable must 694 * be found 695 * @return the next focusable component in the bounds or null if none can 696 * be found 697 */ 698 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 699 700 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 701 View focusCandidate = null; 702 703 /* 704 * A fully contained focusable is one where its top is below the bound's 705 * top, and its bottom is above the bound's bottom. A partially 706 * contained focusable is one where some part of it is within the 707 * bounds, but it also has some part that is not within bounds. A fully contained 708 * focusable is preferred to a partially contained focusable. 709 */ 710 boolean foundFullyContainedFocusable = false; 711 712 int count = focusables.size(); 713 for (int i = 0; i < count; i++) { 714 View view = focusables.get(i); 715 int viewTop = view.getTop(); 716 int viewBottom = view.getBottom(); 717 718 if (top < viewBottom && viewTop < bottom) { 719 /* 720 * the focusable is in the target area, it is a candidate for 721 * focusing 722 */ 723 724 final boolean viewIsFullyContained = (top < viewTop) && 725 (viewBottom < bottom); 726 727 if (focusCandidate == null) { 728 /* No candidate, take this one */ 729 focusCandidate = view; 730 foundFullyContainedFocusable = viewIsFullyContained; 731 } else { 732 final boolean viewIsCloserToBoundary = 733 (topFocus && viewTop < focusCandidate.getTop()) || 734 (!topFocus && viewBottom > focusCandidate 735 .getBottom()); 736 737 if (foundFullyContainedFocusable) { 738 if (viewIsFullyContained && viewIsCloserToBoundary) { 739 /* 740 * We're dealing with only fully contained views, so 741 * it has to be closer to the boundary to beat our 742 * candidate 743 */ 744 focusCandidate = view; 745 } 746 } else { 747 if (viewIsFullyContained) { 748 /* Any fully contained view beats a partially contained view */ 749 focusCandidate = view; 750 foundFullyContainedFocusable = true; 751 } else if (viewIsCloserToBoundary) { 752 /* 753 * Partially contained view beats another partially 754 * contained view if it's closer 755 */ 756 focusCandidate = view; 757 } 758 } 759 } 760 } 761 } 762 763 return focusCandidate; 764 } 765 766 /** 767 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 768 * method will scroll the view by one page up or down and give the focus 769 * to the topmost/bottommost component in the new visible area. If no 770 * component is a good candidate for focus, this scrollview reclaims the 771 * focus.</p> 772 * 773 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 774 * to go one page up or 775 * {@link android.view.View#FOCUS_DOWN} to go one page down 776 * @return true if the key event is consumed by this method, false otherwise 777 */ 778 public boolean pageScroll(int direction) { 779 boolean down = direction == View.FOCUS_DOWN; 780 int height = getHeight(); 781 782 if (down) { 783 mTempRect.top = getScrollY() + height; 784 int count = getChildCount(); 785 if (count > 0) { 786 View view = getChildAt(count - 1); 787 if (mTempRect.top + height > view.getBottom()) { 788 mTempRect.top = view.getBottom() - height; 789 } 790 } 791 } else { 792 mTempRect.top = getScrollY() - height; 793 if (mTempRect.top < 0) { 794 mTempRect.top = 0; 795 } 796 } 797 mTempRect.bottom = mTempRect.top + height; 798 799 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 800 } 801 802 /** 803 * <p>Handles scrolling in response to a "home/end" shortcut press. This 804 * method will scroll the view to the top or bottom and give the focus 805 * to the topmost/bottommost component in the new visible area. If no 806 * component is a good candidate for focus, this scrollview reclaims the 807 * focus.</p> 808 * 809 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 810 * to go the top of the view or 811 * {@link android.view.View#FOCUS_DOWN} to go the bottom 812 * @return true if the key event is consumed by this method, false otherwise 813 */ 814 public boolean fullScroll(int direction) { 815 boolean down = direction == View.FOCUS_DOWN; 816 int height = getHeight(); 817 818 mTempRect.top = 0; 819 mTempRect.bottom = height; 820 821 if (down) { 822 int count = getChildCount(); 823 if (count > 0) { 824 View view = getChildAt(count - 1); 825 mTempRect.bottom = view.getBottom(); 826 mTempRect.top = mTempRect.bottom - height; 827 } 828 } 829 830 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 831 } 832 833 /** 834 * <p>Scrolls the view to make the area defined by <code>top</code> and 835 * <code>bottom</code> visible. This method attempts to give the focus 836 * to a component visible in this area. If no component can be focused in 837 * the new visible area, the focus is reclaimed by this scrollview.</p> 838 * 839 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 840 * to go upward 841 * {@link android.view.View#FOCUS_DOWN} to downward 842 * @param top the top offset of the new area to be made visible 843 * @param bottom the bottom offset of the new area to be made visible 844 * @return true if the key event is consumed by this method, false otherwise 845 */ 846 private boolean scrollAndFocus(int direction, int top, int bottom) { 847 boolean handled = true; 848 849 int height = getHeight(); 850 int containerTop = getScrollY(); 851 int containerBottom = containerTop + height; 852 boolean up = direction == View.FOCUS_UP; 853 854 View newFocused = findFocusableViewInBounds(up, top, bottom); 855 if (newFocused == null) { 856 newFocused = this; 857 } 858 859 if (top >= containerTop && bottom <= containerBottom) { 860 handled = false; 861 } else { 862 int delta = up ? (top - containerTop) : (bottom - containerBottom); 863 doScrollY(delta); 864 } 865 866 if (newFocused != findFocus() && newFocused.requestFocus(direction)) { 867 mScrollViewMovedFocus = true; 868 mScrollViewMovedFocus = false; 869 } 870 871 return handled; 872 } 873 874 /** 875 * Handle scrolling in response to an up or down arrow click. 876 * 877 * @param direction The direction corresponding to the arrow key that was 878 * pressed 879 * @return True if we consumed the event, false otherwise 880 */ 881 public boolean arrowScroll(int direction) { 882 883 View currentFocused = findFocus(); 884 if (currentFocused == this) currentFocused = null; 885 886 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 887 888 final int maxJump = getMaxScrollAmount(); 889 890 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 891 nextFocused.getDrawingRect(mTempRect); 892 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 893 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 894 doScrollY(scrollDelta); 895 nextFocused.requestFocus(direction); 896 } else { 897 // no new focus 898 int scrollDelta = maxJump; 899 900 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 901 scrollDelta = getScrollY(); 902 } else if (direction == View.FOCUS_DOWN) { 903 if (getChildCount() > 0) { 904 int daBottom = getChildAt(0).getBottom(); 905 906 int screenBottom = getScrollY() + getHeight(); 907 908 if (daBottom - screenBottom < maxJump) { 909 scrollDelta = daBottom - screenBottom; 910 } 911 } 912 } 913 if (scrollDelta == 0) { 914 return false; 915 } 916 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 917 } 918 919 if (currentFocused != null && currentFocused.isFocused() 920 && isOffScreen(currentFocused)) { 921 // previously focused item still has focus and is off screen, give 922 // it up (take it back to ourselves) 923 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 924 // sure to 925 // get it) 926 final int descendantFocusability = getDescendantFocusability(); // save 927 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 928 requestFocus(); 929 setDescendantFocusability(descendantFocusability); // restore 930 } 931 return true; 932 } 933 934 /** 935 * @return whether the descendant of this scroll view is scrolled off 936 * screen. 937 */ 938 private boolean isOffScreen(View descendant) { 939 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 940 } 941 942 /** 943 * @return whether the descendant of this scroll view is within delta 944 * pixels of being on the screen. 945 */ 946 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 947 descendant.getDrawingRect(mTempRect); 948 offsetDescendantRectToMyCoords(descendant, mTempRect); 949 950 return (mTempRect.bottom + delta) >= getScrollY() 951 && (mTempRect.top - delta) <= (getScrollY() + height); 952 } 953 954 /** 955 * Smooth scroll by a Y delta 956 * 957 * @param delta the number of pixels to scroll by on the Y axis 958 */ 959 private void doScrollY(int delta) { 960 if (delta != 0) { 961 if (mSmoothScrollingEnabled) { 962 smoothScrollBy(0, delta); 963 } else { 964 scrollBy(0, delta); 965 } 966 } 967 } 968 969 /** 970 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 971 * 972 * @param dx the number of pixels to scroll by on the X axis 973 * @param dy the number of pixels to scroll by on the Y axis 974 */ 975 public final void smoothScrollBy(int dx, int dy) { 976 if (getChildCount() == 0) { 977 // Nothing to do. 978 return; 979 } 980 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 981 if (duration > ANIMATED_SCROLL_GAP) { 982 final int height = getHeight() - mPaddingBottom - mPaddingTop; 983 final int bottom = getChildAt(0).getHeight(); 984 final int maxY = Math.max(0, bottom - height); 985 final int scrollY = mScrollY; 986 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 987 988 mScroller.startScroll(mScrollX, scrollY, 0, dy); 989 invalidate(); 990 } else { 991 if (!mScroller.isFinished()) { 992 mScroller.abortAnimation(); 993 } 994 scrollBy(dx, dy); 995 } 996 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 997 } 998 999 /** 1000 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1001 * 1002 * @param x the position where to scroll on the X axis 1003 * @param y the position where to scroll on the Y axis 1004 */ 1005 public final void smoothScrollTo(int x, int y) { 1006 smoothScrollBy(x - mScrollX, y - mScrollY); 1007 } 1008 1009 /** 1010 * <p>The scroll range of a scroll view is the overall height of all of its 1011 * children.</p> 1012 */ 1013 @Override 1014 protected int computeVerticalScrollRange() { 1015 final int count = getChildCount(); 1016 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1017 if (count == 0) { 1018 return contentHeight; 1019 } 1020 1021 int scrollRange = getChildAt(0).getBottom(); 1022 final int scrollY = mScrollY; 1023 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1024 if (scrollY < 0) { 1025 scrollRange -= scrollY; 1026 } else if (scrollY > overscrollBottom) { 1027 scrollRange += scrollY - overscrollBottom; 1028 } 1029 1030 return scrollRange; 1031 } 1032 1033 @Override 1034 protected int computeVerticalScrollOffset() { 1035 return Math.max(0, super.computeVerticalScrollOffset()); 1036 } 1037 1038 @Override 1039 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1040 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1041 1042 int childWidthMeasureSpec; 1043 int childHeightMeasureSpec; 1044 1045 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1046 + mPaddingRight, lp.width); 1047 1048 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1049 1050 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1051 } 1052 1053 @Override 1054 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1055 int parentHeightMeasureSpec, int heightUsed) { 1056 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1057 1058 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1059 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1060 + widthUsed, lp.width); 1061 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1062 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1063 1064 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1065 } 1066 1067 @Override 1068 public void computeScroll() { 1069 if (mScroller.computeScrollOffset()) { 1070 // This is called at drawing time by ViewGroup. We don't want to 1071 // re-show the scrollbars at this point, which scrollTo will do, 1072 // so we replicate most of scrollTo here. 1073 // 1074 // It's a little odd to call onScrollChanged from inside the drawing. 1075 // 1076 // It is, except when you remember that computeScroll() is used to 1077 // animate scrolling. So unless we want to defer the onScrollChanged() 1078 // until the end of the animated scrolling, we don't really have a 1079 // choice here. 1080 // 1081 // I agree. The alternative, which I think would be worse, is to post 1082 // something and tell the subclasses later. This is bad because there 1083 // will be a window where mScrollX/Y is different from what the app 1084 // thinks it is. 1085 // 1086 int oldX = mScrollX; 1087 int oldY = mScrollY; 1088 int x = mScroller.getCurrX(); 1089 int y = mScroller.getCurrY(); 1090 1091 if (oldX != x || oldY != y) { 1092 overscrollBy(x - oldX, y - oldY, oldX, oldY, 0, getScrollRange(), 1093 0, mOverflingDistance, false); 1094 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1095 1096 final int range = getScrollRange(); 1097 final int overscrollMode = getOverscrollMode(); 1098 if (overscrollMode == OVERSCROLL_ALWAYS || 1099 (overscrollMode == OVERSCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1100 if (y < 0 && oldY >= 0) { 1101 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1102 } else if (y > range && oldY <= range) { 1103 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1104 } 1105 } 1106 } 1107 awakenScrollBars(); 1108 1109 // Keep on drawing until the animation has finished. 1110 postInvalidate(); 1111 } 1112 } 1113 1114 /** 1115 * Scrolls the view to the given child. 1116 * 1117 * @param child the View to scroll to 1118 */ 1119 private void scrollToChild(View child) { 1120 child.getDrawingRect(mTempRect); 1121 1122 /* Offset from child's local coordinates to ScrollView coordinates */ 1123 offsetDescendantRectToMyCoords(child, mTempRect); 1124 1125 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1126 1127 if (scrollDelta != 0) { 1128 scrollBy(0, scrollDelta); 1129 } 1130 } 1131 1132 /** 1133 * If rect is off screen, scroll just enough to get it (or at least the 1134 * first screen size chunk of it) on screen. 1135 * 1136 * @param rect The rectangle. 1137 * @param immediate True to scroll immediately without animation 1138 * @return true if scrolling was performed 1139 */ 1140 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1141 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1142 final boolean scroll = delta != 0; 1143 if (scroll) { 1144 if (immediate) { 1145 scrollBy(0, delta); 1146 } else { 1147 smoothScrollBy(0, delta); 1148 } 1149 } 1150 return scroll; 1151 } 1152 1153 /** 1154 * Compute the amount to scroll in the Y direction in order to get 1155 * a rectangle completely on the screen (or, if taller than the screen, 1156 * at least the first screen size chunk of it). 1157 * 1158 * @param rect The rect. 1159 * @return The scroll delta. 1160 */ 1161 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1162 if (getChildCount() == 0) return 0; 1163 1164 int height = getHeight(); 1165 int screenTop = getScrollY(); 1166 int screenBottom = screenTop + height; 1167 1168 int fadingEdge = getVerticalFadingEdgeLength(); 1169 1170 // leave room for top fading edge as long as rect isn't at very top 1171 if (rect.top > 0) { 1172 screenTop += fadingEdge; 1173 } 1174 1175 // leave room for bottom fading edge as long as rect isn't at very bottom 1176 if (rect.bottom < getChildAt(0).getHeight()) { 1177 screenBottom -= fadingEdge; 1178 } 1179 1180 int scrollYDelta = 0; 1181 1182 if (rect.bottom > screenBottom && rect.top > screenTop) { 1183 // need to move down to get it in view: move down just enough so 1184 // that the entire rectangle is in view (or at least the first 1185 // screen size chunk). 1186 1187 if (rect.height() > height) { 1188 // just enough to get screen size chunk on 1189 scrollYDelta += (rect.top - screenTop); 1190 } else { 1191 // get entire rect at bottom of screen 1192 scrollYDelta += (rect.bottom - screenBottom); 1193 } 1194 1195 // make sure we aren't scrolling beyond the end of our content 1196 int bottom = getChildAt(0).getBottom(); 1197 int distanceToBottom = bottom - screenBottom; 1198 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1199 1200 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1201 // need to move up to get it in view: move up just enough so that 1202 // entire rectangle is in view (or at least the first screen 1203 // size chunk of it). 1204 1205 if (rect.height() > height) { 1206 // screen size chunk 1207 scrollYDelta -= (screenBottom - rect.bottom); 1208 } else { 1209 // entire rect at top 1210 scrollYDelta -= (screenTop - rect.top); 1211 } 1212 1213 // make sure we aren't scrolling any further than the top our content 1214 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1215 } 1216 return scrollYDelta; 1217 } 1218 1219 @Override 1220 public void requestChildFocus(View child, View focused) { 1221 if (!mScrollViewMovedFocus) { 1222 if (!mIsLayoutDirty) { 1223 scrollToChild(focused); 1224 } else { 1225 // The child may not be laid out yet, we can't compute the scroll yet 1226 mChildToScrollTo = focused; 1227 } 1228 } 1229 super.requestChildFocus(child, focused); 1230 } 1231 1232 1233 /** 1234 * When looking for focus in children of a scroll view, need to be a little 1235 * more careful not to give focus to something that is scrolled off screen. 1236 * 1237 * This is more expensive than the default {@link android.view.ViewGroup} 1238 * implementation, otherwise this behavior might have been made the default. 1239 */ 1240 @Override 1241 protected boolean onRequestFocusInDescendants(int direction, 1242 Rect previouslyFocusedRect) { 1243 1244 // convert from forward / backward notation to up / down / left / right 1245 // (ugh). 1246 if (direction == View.FOCUS_FORWARD) { 1247 direction = View.FOCUS_DOWN; 1248 } else if (direction == View.FOCUS_BACKWARD) { 1249 direction = View.FOCUS_UP; 1250 } 1251 1252 final View nextFocus = previouslyFocusedRect == null ? 1253 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1254 FocusFinder.getInstance().findNextFocusFromRect(this, 1255 previouslyFocusedRect, direction); 1256 1257 if (nextFocus == null) { 1258 return false; 1259 } 1260 1261 if (isOffScreen(nextFocus)) { 1262 return false; 1263 } 1264 1265 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1266 } 1267 1268 @Override 1269 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1270 boolean immediate) { 1271 // offset into coordinate space of this scroll view 1272 rectangle.offset(child.getLeft() - child.getScrollX(), 1273 child.getTop() - child.getScrollY()); 1274 1275 return scrollToChildRect(rectangle, immediate); 1276 } 1277 1278 @Override 1279 public void requestLayout() { 1280 mIsLayoutDirty = true; 1281 super.requestLayout(); 1282 } 1283 1284 @Override 1285 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1286 super.onLayout(changed, l, t, r, b); 1287 mIsLayoutDirty = false; 1288 // Give a child focus if it needs it 1289 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1290 scrollToChild(mChildToScrollTo); 1291 } 1292 mChildToScrollTo = null; 1293 1294 // Calling this with the present values causes it to re-clam them 1295 scrollTo(mScrollX, mScrollY); 1296 } 1297 1298 @Override 1299 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1300 super.onSizeChanged(w, h, oldw, oldh); 1301 1302 View currentFocused = findFocus(); 1303 if (null == currentFocused || this == currentFocused) 1304 return; 1305 1306 // If the currently-focused view was visible on the screen when the 1307 // screen was at the old height, then scroll the screen to make that 1308 // view visible with the new screen height. 1309 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1310 currentFocused.getDrawingRect(mTempRect); 1311 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1312 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1313 doScrollY(scrollDelta); 1314 } 1315 } 1316 1317 /** 1318 * Return true if child is an descendant of parent, (or equal to the parent). 1319 */ 1320 private boolean isViewDescendantOf(View child, View parent) { 1321 if (child == parent) { 1322 return true; 1323 } 1324 1325 final ViewParent theParent = child.getParent(); 1326 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1327 } 1328 1329 /** 1330 * Fling the scroll view 1331 * 1332 * @param velocityY The initial velocity in the Y direction. Positive 1333 * numbers mean that the finger/cursor is moving down the screen, 1334 * which means we want to scroll towards the top. 1335 */ 1336 public void fling(int velocityY) { 1337 if (getChildCount() > 0) { 1338 int height = getHeight() - mPaddingBottom - mPaddingTop; 1339 int bottom = getChildAt(0).getHeight(); 1340 1341 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1342 Math.max(0, bottom - height), 0, height/2); 1343 1344 final boolean movingDown = velocityY > 0; 1345 1346 View newFocused = 1347 findFocusableViewInMyBounds(movingDown, mScroller.getFinalY(), findFocus()); 1348 if (newFocused == null) { 1349 newFocused = this; 1350 } 1351 1352 if (newFocused != findFocus() 1353 && newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : View.FOCUS_UP)) { 1354 mScrollViewMovedFocus = true; 1355 mScrollViewMovedFocus = false; 1356 } 1357 1358 invalidate(); 1359 } 1360 } 1361 1362 /** 1363 * {@inheritDoc} 1364 * 1365 * <p>This version also clamps the scrolling to the bounds of our child. 1366 */ 1367 @Override 1368 public void scrollTo(int x, int y) { 1369 // we rely on the fact the View.scrollBy calls scrollTo. 1370 if (getChildCount() > 0) { 1371 View child = getChildAt(0); 1372 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1373 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1374 if (x != mScrollX || y != mScrollY) { 1375 super.scrollTo(x, y); 1376 } 1377 } 1378 } 1379 1380 @Override 1381 public void setOverscrollMode(int mode) { 1382 if (mode != OVERSCROLL_NEVER) { 1383 if (mEdgeGlowTop == null) { 1384 final Resources res = getContext().getResources(); 1385 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1386 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1387 mEdgeGlowTop = new EdgeGlow(edge, glow); 1388 mEdgeGlowBottom = new EdgeGlow(edge, glow); 1389 } 1390 } else { 1391 mEdgeGlowTop = null; 1392 mEdgeGlowBottom = null; 1393 } 1394 super.setOverscrollMode(mode); 1395 } 1396 1397 @Override 1398 public void draw(Canvas canvas) { 1399 super.draw(canvas); 1400 if (mEdgeGlowTop != null) { 1401 final int scrollY = mScrollY; 1402 if (!mEdgeGlowTop.isFinished()) { 1403 final int restoreCount = canvas.save(); 1404 final int width = getWidth(); 1405 1406 canvas.translate(-width / 2, Math.min(0, scrollY)); 1407 mEdgeGlowTop.setSize(width * 2, getHeight()); 1408 if (mEdgeGlowTop.draw(canvas)) { 1409 invalidate(); 1410 } 1411 canvas.restoreToCount(restoreCount); 1412 } 1413 if (!mEdgeGlowBottom.isFinished()) { 1414 final int restoreCount = canvas.save(); 1415 final int width = getWidth(); 1416 final int height = getHeight(); 1417 1418 canvas.translate(-width / 2, Math.max(getScrollRange(), scrollY) + height); 1419 canvas.rotate(180, width, 0); 1420 mEdgeGlowBottom.setSize(width * 2, height); 1421 if (mEdgeGlowBottom.draw(canvas)) { 1422 invalidate(); 1423 } 1424 canvas.restoreToCount(restoreCount); 1425 } 1426 } 1427 } 1428 1429 private int clamp(int n, int my, int child) { 1430 if (my >= child || n < 0) { 1431 /* my >= child is this case: 1432 * |--------------- me ---------------| 1433 * |------ child ------| 1434 * or 1435 * |--------------- me ---------------| 1436 * |------ child ------| 1437 * or 1438 * |--------------- me ---------------| 1439 * |------ child ------| 1440 * 1441 * n < 0 is this case: 1442 * |------ me ------| 1443 * |-------- child --------| 1444 * |-- mScrollX --| 1445 */ 1446 return 0; 1447 } 1448 if ((my+n) > child) { 1449 /* this case: 1450 * |------ me ------| 1451 * |------ child ------| 1452 * |-- mScrollX --| 1453 */ 1454 return child-my; 1455 } 1456 return n; 1457 } 1458} 1459