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 17 package android.widget; 18 19 import com.android.internal.R; 20 21 import android.content.Context; 22 import android.content.res.Resources; 23 import android.content.res.TypedArray; 24 import android.graphics.Canvas; 25 import android.graphics.Rect; 26 import android.graphics.drawable.Drawable; 27 import android.util.AttributeSet; 28 import android.view.FocusFinder; 29 import android.view.KeyEvent; 30 import android.view.MotionEvent; 31 import android.view.VelocityTracker; 32 import android.view.View; 33 import android.view.ViewConfiguration; 34 import android.view.ViewGroup; 35 import android.view.ViewParent; 36 import android.view.animation.AnimationUtils; 37 38 import java.util.List; 39 40 /** 41 * Layout container for a view hierarchy that can be scrolled by the user, 42 * allowing it to be larger than the physical display. A 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 */ 56 public 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 mIsBeingDragged = true; 502 503 /* 504 * If being flinged and user touches, stop the fling. isFinished 505 * will be false if being flinged. 506 */ 507 if (!mScroller.isFinished()) { 508 mScroller.abortAnimation(); 509 } 510 511 // Remember where the motion event started 512 mLastMotionY = y; 513 mActivePointerId = ev.getPointerId(0); 514 break; 515 } 516 case MotionEvent.ACTION_MOVE: 517 if (mIsBeingDragged) { 518 // Scroll to follow the motion event 519 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 520 final float y = ev.getY(activePointerIndex); 521 final int deltaY = (int) (mLastMotionY - y); 522 mLastMotionY = y; 523 524 final int oldX = mScrollX; 525 final int oldY = mScrollY; 526 final int range = getScrollRange(); 527 if (overScrollBy(0, deltaY, 0, mScrollY, 0, range, 528 0, mOverscrollDistance, true)) { 529 // Break our velocity if we hit a scroll barrier. 530 mVelocityTracker.clear(); 531 } 532 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 533 534 final int overscrollMode = getOverScrollMode(); 535 if (overscrollMode == OVER_SCROLL_ALWAYS || 536 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 537 final int pulledToY = oldY + deltaY; 538 if (pulledToY < 0) { 539 mEdgeGlowTop.onPull((float) deltaY / getHeight()); 540 if (!mEdgeGlowBottom.isFinished()) { 541 mEdgeGlowBottom.onRelease(); 542 } 543 } else if (pulledToY > range) { 544 mEdgeGlowBottom.onPull((float) deltaY / getHeight()); 545 if (!mEdgeGlowTop.isFinished()) { 546 mEdgeGlowTop.onRelease(); 547 } 548 } 549 if (mEdgeGlowTop != null 550 && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { 551 invalidate(); 552 } 553 } 554 } 555 break; 556 case MotionEvent.ACTION_UP: 557 if (mIsBeingDragged) { 558 final VelocityTracker velocityTracker = mVelocityTracker; 559 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 560 int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId); 561 562 if (getChildCount() > 0) { 563 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 564 fling(-initialVelocity); 565 } else { 566 final int bottom = getScrollRange(); 567 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, bottom)) { 568 invalidate(); 569 } 570 } 571 } 572 573 mActivePointerId = INVALID_POINTER; 574 mIsBeingDragged = false; 575 576 if (mVelocityTracker != null) { 577 mVelocityTracker.recycle(); 578 mVelocityTracker = null; 579 } 580 if (mEdgeGlowTop != null) { 581 mEdgeGlowTop.onRelease(); 582 mEdgeGlowBottom.onRelease(); 583 } 584 } 585 break; 586 case MotionEvent.ACTION_CANCEL: 587 if (mIsBeingDragged && getChildCount() > 0) { 588 if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { 589 invalidate(); 590 } 591 mActivePointerId = INVALID_POINTER; 592 mIsBeingDragged = false; 593 if (mVelocityTracker != null) { 594 mVelocityTracker.recycle(); 595 mVelocityTracker = null; 596 } 597 if (mEdgeGlowTop != null) { 598 mEdgeGlowTop.onRelease(); 599 mEdgeGlowBottom.onRelease(); 600 } 601 } 602 break; 603 case MotionEvent.ACTION_POINTER_UP: 604 onSecondaryPointerUp(ev); 605 break; 606 } 607 return true; 608 } 609 610 private void onSecondaryPointerUp(MotionEvent ev) { 611 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 612 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 613 final int pointerId = ev.getPointerId(pointerIndex); 614 if (pointerId == mActivePointerId) { 615 // This was our active pointer going up. Choose a new 616 // active pointer and adjust accordingly. 617 // TODO: Make this decision more intelligent. 618 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 619 mLastMotionY = ev.getY(newPointerIndex); 620 mActivePointerId = ev.getPointerId(newPointerIndex); 621 if (mVelocityTracker != null) { 622 mVelocityTracker.clear(); 623 } 624 } 625 } 626 627 @Override 628 protected void onOverScrolled(int scrollX, int scrollY, 629 boolean clampedX, boolean clampedY) { 630 // Treat animating scrolls differently; see #computeScroll() for why. 631 if (!mScroller.isFinished()) { 632 mScrollX = scrollX; 633 mScrollY = scrollY; 634 if (clampedY) { 635 mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange()); 636 } 637 } else { 638 super.scrollTo(scrollX, scrollY); 639 } 640 awakenScrollBars(); 641 } 642 643 private int getScrollRange() { 644 int scrollRange = 0; 645 if (getChildCount() > 0) { 646 View child = getChildAt(0); 647 scrollRange = Math.max(0, 648 child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop)); 649 } 650 return scrollRange; 651 } 652 653 /** 654 * <p> 655 * Finds the next focusable component that fits in this View's bounds 656 * (excluding fading edges) pretending that this View's top is located at 657 * the parameter top. 658 * </p> 659 * 660 * @param topFocus look for a candidate is the one at the top of the bounds 661 * if topFocus is true, or at the bottom of the bounds if topFocus is 662 * false 663 * @param top the top offset of the bounds in which a focusable must be 664 * found (the fading edge is assumed to start at this position) 665 * @param preferredFocusable the View that has highest priority and will be 666 * returned if it is within my bounds (null is valid) 667 * @return the next focusable component in the bounds or null if none can be 668 * found 669 */ 670 private View findFocusableViewInMyBounds(final boolean topFocus, 671 final int top, View preferredFocusable) { 672 /* 673 * The fading edge's transparent side should be considered for focus 674 * since it's mostly visible, so we divide the actual fading edge length 675 * by 2. 676 */ 677 final int fadingEdgeLength = getVerticalFadingEdgeLength() / 2; 678 final int topWithoutFadingEdge = top + fadingEdgeLength; 679 final int bottomWithoutFadingEdge = top + getHeight() - fadingEdgeLength; 680 681 if ((preferredFocusable != null) 682 && (preferredFocusable.getTop() < bottomWithoutFadingEdge) 683 && (preferredFocusable.getBottom() > topWithoutFadingEdge)) { 684 return preferredFocusable; 685 } 686 687 return findFocusableViewInBounds(topFocus, topWithoutFadingEdge, 688 bottomWithoutFadingEdge); 689 } 690 691 /** 692 * <p> 693 * Finds the next focusable component that fits in the specified bounds. 694 * </p> 695 * 696 * @param topFocus look for a candidate is the one at the top of the bounds 697 * if topFocus is true, or at the bottom of the bounds if topFocus is 698 * false 699 * @param top the top offset of the bounds in which a focusable must be 700 * found 701 * @param bottom the bottom offset of the bounds in which a focusable must 702 * be found 703 * @return the next focusable component in the bounds or null if none can 704 * be found 705 */ 706 private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { 707 708 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 709 View focusCandidate = null; 710 711 /* 712 * A fully contained focusable is one where its top is below the bound's 713 * top, and its bottom is above the bound's bottom. A partially 714 * contained focusable is one where some part of it is within the 715 * bounds, but it also has some part that is not within bounds. A fully contained 716 * focusable is preferred to a partially contained focusable. 717 */ 718 boolean foundFullyContainedFocusable = false; 719 720 int count = focusables.size(); 721 for (int i = 0; i < count; i++) { 722 View view = focusables.get(i); 723 int viewTop = view.getTop(); 724 int viewBottom = view.getBottom(); 725 726 if (top < viewBottom && viewTop < bottom) { 727 /* 728 * the focusable is in the target area, it is a candidate for 729 * focusing 730 */ 731 732 final boolean viewIsFullyContained = (top < viewTop) && 733 (viewBottom < bottom); 734 735 if (focusCandidate == null) { 736 /* No candidate, take this one */ 737 focusCandidate = view; 738 foundFullyContainedFocusable = viewIsFullyContained; 739 } else { 740 final boolean viewIsCloserToBoundary = 741 (topFocus && viewTop < focusCandidate.getTop()) || 742 (!topFocus && viewBottom > focusCandidate 743 .getBottom()); 744 745 if (foundFullyContainedFocusable) { 746 if (viewIsFullyContained && viewIsCloserToBoundary) { 747 /* 748 * We're dealing with only fully contained views, so 749 * it has to be closer to the boundary to beat our 750 * candidate 751 */ 752 focusCandidate = view; 753 } 754 } else { 755 if (viewIsFullyContained) { 756 /* Any fully contained view beats a partially contained view */ 757 focusCandidate = view; 758 foundFullyContainedFocusable = true; 759 } else if (viewIsCloserToBoundary) { 760 /* 761 * Partially contained view beats another partially 762 * contained view if it's closer 763 */ 764 focusCandidate = view; 765 } 766 } 767 } 768 } 769 } 770 771 return focusCandidate; 772 } 773 774 /** 775 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 776 * method will scroll the view by one page up or down and give the focus 777 * to the topmost/bottommost component in the new visible area. If no 778 * component is a good candidate for focus, this scrollview reclaims the 779 * focus.</p> 780 * 781 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 782 * to go one page up or 783 * {@link android.view.View#FOCUS_DOWN} to go one page down 784 * @return true if the key event is consumed by this method, false otherwise 785 */ 786 public boolean pageScroll(int direction) { 787 boolean down = direction == View.FOCUS_DOWN; 788 int height = getHeight(); 789 790 if (down) { 791 mTempRect.top = getScrollY() + height; 792 int count = getChildCount(); 793 if (count > 0) { 794 View view = getChildAt(count - 1); 795 if (mTempRect.top + height > view.getBottom()) { 796 mTempRect.top = view.getBottom() - height; 797 } 798 } 799 } else { 800 mTempRect.top = getScrollY() - height; 801 if (mTempRect.top < 0) { 802 mTempRect.top = 0; 803 } 804 } 805 mTempRect.bottom = mTempRect.top + height; 806 807 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 808 } 809 810 /** 811 * <p>Handles scrolling in response to a "home/end" shortcut press. This 812 * method will scroll the view to the top or bottom and give the focus 813 * to the topmost/bottommost component in the new visible area. If no 814 * component is a good candidate for focus, this scrollview reclaims the 815 * focus.</p> 816 * 817 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 818 * to go the top of the view or 819 * {@link android.view.View#FOCUS_DOWN} to go the bottom 820 * @return true if the key event is consumed by this method, false otherwise 821 */ 822 public boolean fullScroll(int direction) { 823 boolean down = direction == View.FOCUS_DOWN; 824 int height = getHeight(); 825 826 mTempRect.top = 0; 827 mTempRect.bottom = height; 828 829 if (down) { 830 int count = getChildCount(); 831 if (count > 0) { 832 View view = getChildAt(count - 1); 833 mTempRect.bottom = view.getBottom(); 834 mTempRect.top = mTempRect.bottom - height; 835 } 836 } 837 838 return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); 839 } 840 841 /** 842 * <p>Scrolls the view to make the area defined by <code>top</code> and 843 * <code>bottom</code> visible. This method attempts to give the focus 844 * to a component visible in this area. If no component can be focused in 845 * the new visible area, the focus is reclaimed by this scrollview.</p> 846 * 847 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} 848 * to go upward 849 * {@link android.view.View#FOCUS_DOWN} to downward 850 * @param top the top offset of the new area to be made visible 851 * @param bottom the bottom offset of the new area to be made visible 852 * @return true if the key event is consumed by this method, false otherwise 853 */ 854 private boolean scrollAndFocus(int direction, int top, int bottom) { 855 boolean handled = true; 856 857 int height = getHeight(); 858 int containerTop = getScrollY(); 859 int containerBottom = containerTop + height; 860 boolean up = direction == View.FOCUS_UP; 861 862 View newFocused = findFocusableViewInBounds(up, top, bottom); 863 if (newFocused == null) { 864 newFocused = this; 865 } 866 867 if (top >= containerTop && bottom <= containerBottom) { 868 handled = false; 869 } else { 870 int delta = up ? (top - containerTop) : (bottom - containerBottom); 871 doScrollY(delta); 872 } 873 874 if (newFocused != findFocus() && newFocused.requestFocus(direction)) { 875 mScrollViewMovedFocus = true; 876 mScrollViewMovedFocus = false; 877 } 878 879 return handled; 880 } 881 882 /** 883 * Handle scrolling in response to an up or down arrow click. 884 * 885 * @param direction The direction corresponding to the arrow key that was 886 * pressed 887 * @return True if we consumed the event, false otherwise 888 */ 889 public boolean arrowScroll(int direction) { 890 891 View currentFocused = findFocus(); 892 if (currentFocused == this) currentFocused = null; 893 894 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 895 896 final int maxJump = getMaxScrollAmount(); 897 898 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { 899 nextFocused.getDrawingRect(mTempRect); 900 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 901 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 902 doScrollY(scrollDelta); 903 nextFocused.requestFocus(direction); 904 } else { 905 // no new focus 906 int scrollDelta = maxJump; 907 908 if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { 909 scrollDelta = getScrollY(); 910 } else if (direction == View.FOCUS_DOWN) { 911 if (getChildCount() > 0) { 912 int daBottom = getChildAt(0).getBottom(); 913 914 int screenBottom = getScrollY() + getHeight(); 915 916 if (daBottom - screenBottom < maxJump) { 917 scrollDelta = daBottom - screenBottom; 918 } 919 } 920 } 921 if (scrollDelta == 0) { 922 return false; 923 } 924 doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); 925 } 926 927 if (currentFocused != null && currentFocused.isFocused() 928 && isOffScreen(currentFocused)) { 929 // previously focused item still has focus and is off screen, give 930 // it up (take it back to ourselves) 931 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 932 // sure to 933 // get it) 934 final int descendantFocusability = getDescendantFocusability(); // save 935 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 936 requestFocus(); 937 setDescendantFocusability(descendantFocusability); // restore 938 } 939 return true; 940 } 941 942 /** 943 * @return whether the descendant of this scroll view is scrolled off 944 * screen. 945 */ 946 private boolean isOffScreen(View descendant) { 947 return !isWithinDeltaOfScreen(descendant, 0, getHeight()); 948 } 949 950 /** 951 * @return whether the descendant of this scroll view is within delta 952 * pixels of being on the screen. 953 */ 954 private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { 955 descendant.getDrawingRect(mTempRect); 956 offsetDescendantRectToMyCoords(descendant, mTempRect); 957 958 return (mTempRect.bottom + delta) >= getScrollY() 959 && (mTempRect.top - delta) <= (getScrollY() + height); 960 } 961 962 /** 963 * Smooth scroll by a Y delta 964 * 965 * @param delta the number of pixels to scroll by on the Y axis 966 */ 967 private void doScrollY(int delta) { 968 if (delta != 0) { 969 if (mSmoothScrollingEnabled) { 970 smoothScrollBy(0, delta); 971 } else { 972 scrollBy(0, delta); 973 } 974 } 975 } 976 977 /** 978 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 979 * 980 * @param dx the number of pixels to scroll by on the X axis 981 * @param dy the number of pixels to scroll by on the Y axis 982 */ 983 public final void smoothScrollBy(int dx, int dy) { 984 if (getChildCount() == 0) { 985 // Nothing to do. 986 return; 987 } 988 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 989 if (duration > ANIMATED_SCROLL_GAP) { 990 final int height = getHeight() - mPaddingBottom - mPaddingTop; 991 final int bottom = getChildAt(0).getHeight(); 992 final int maxY = Math.max(0, bottom - height); 993 final int scrollY = mScrollY; 994 dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; 995 996 mScroller.startScroll(mScrollX, scrollY, 0, dy); 997 invalidate(); 998 } else { 999 if (!mScroller.isFinished()) { 1000 mScroller.abortAnimation(); 1001 } 1002 scrollBy(dx, dy); 1003 } 1004 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1005 } 1006 1007 /** 1008 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1009 * 1010 * @param x the position where to scroll on the X axis 1011 * @param y the position where to scroll on the Y axis 1012 */ 1013 public final void smoothScrollTo(int x, int y) { 1014 smoothScrollBy(x - mScrollX, y - mScrollY); 1015 } 1016 1017 /** 1018 * <p>The scroll range of a scroll view is the overall height of all of its 1019 * children.</p> 1020 */ 1021 @Override 1022 protected int computeVerticalScrollRange() { 1023 final int count = getChildCount(); 1024 final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop; 1025 if (count == 0) { 1026 return contentHeight; 1027 } 1028 1029 int scrollRange = getChildAt(0).getBottom(); 1030 final int scrollY = mScrollY; 1031 final int overscrollBottom = Math.max(0, scrollRange - contentHeight); 1032 if (scrollY < 0) { 1033 scrollRange -= scrollY; 1034 } else if (scrollY > overscrollBottom) { 1035 scrollRange += scrollY - overscrollBottom; 1036 } 1037 1038 return scrollRange; 1039 } 1040 1041 @Override 1042 protected int computeVerticalScrollOffset() { 1043 return Math.max(0, super.computeVerticalScrollOffset()); 1044 } 1045 1046 @Override 1047 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1048 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1049 1050 int childWidthMeasureSpec; 1051 int childHeightMeasureSpec; 1052 1053 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft 1054 + mPaddingRight, lp.width); 1055 1056 childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1057 1058 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1059 } 1060 1061 @Override 1062 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1063 int parentHeightMeasureSpec, int heightUsed) { 1064 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1065 1066 final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, 1067 mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin 1068 + widthUsed, lp.width); 1069 final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( 1070 lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); 1071 1072 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1073 } 1074 1075 @Override 1076 public void computeScroll() { 1077 if (mScroller.computeScrollOffset()) { 1078 // This is called at drawing time by ViewGroup. We don't want to 1079 // re-show the scrollbars at this point, which scrollTo will do, 1080 // so we replicate most of scrollTo here. 1081 // 1082 // It's a little odd to call onScrollChanged from inside the drawing. 1083 // 1084 // It is, except when you remember that computeScroll() is used to 1085 // animate scrolling. So unless we want to defer the onScrollChanged() 1086 // until the end of the animated scrolling, we don't really have a 1087 // choice here. 1088 // 1089 // I agree. The alternative, which I think would be worse, is to post 1090 // something and tell the subclasses later. This is bad because there 1091 // will be a window where mScrollX/Y is different from what the app 1092 // thinks it is. 1093 // 1094 int oldX = mScrollX; 1095 int oldY = mScrollY; 1096 int x = mScroller.getCurrX(); 1097 int y = mScroller.getCurrY(); 1098 1099 if (oldX != x || oldY != y) { 1100 overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, getScrollRange(), 1101 0, mOverflingDistance, false); 1102 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1103 1104 final int range = getScrollRange(); 1105 final int overscrollMode = getOverScrollMode(); 1106 if (overscrollMode == OVER_SCROLL_ALWAYS || 1107 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1108 if (y < 0 && oldY >= 0) { 1109 mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); 1110 } else if (y > range && oldY <= range) { 1111 mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); 1112 } 1113 } 1114 } 1115 awakenScrollBars(); 1116 1117 // Keep on drawing until the animation has finished. 1118 postInvalidate(); 1119 } 1120 } 1121 1122 /** 1123 * Scrolls the view to the given child. 1124 * 1125 * @param child the View to scroll to 1126 */ 1127 private void scrollToChild(View child) { 1128 child.getDrawingRect(mTempRect); 1129 1130 /* Offset from child's local coordinates to ScrollView coordinates */ 1131 offsetDescendantRectToMyCoords(child, mTempRect); 1132 1133 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1134 1135 if (scrollDelta != 0) { 1136 scrollBy(0, scrollDelta); 1137 } 1138 } 1139 1140 /** 1141 * If rect is off screen, scroll just enough to get it (or at least the 1142 * first screen size chunk of it) on screen. 1143 * 1144 * @param rect The rectangle. 1145 * @param immediate True to scroll immediately without animation 1146 * @return true if scrolling was performed 1147 */ 1148 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1149 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1150 final boolean scroll = delta != 0; 1151 if (scroll) { 1152 if (immediate) { 1153 scrollBy(0, delta); 1154 } else { 1155 smoothScrollBy(0, delta); 1156 } 1157 } 1158 return scroll; 1159 } 1160 1161 /** 1162 * Compute the amount to scroll in the Y direction in order to get 1163 * a rectangle completely on the screen (or, if taller than the screen, 1164 * at least the first screen size chunk of it). 1165 * 1166 * @param rect The rect. 1167 * @return The scroll delta. 1168 */ 1169 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1170 if (getChildCount() == 0) return 0; 1171 1172 int height = getHeight(); 1173 int screenTop = getScrollY(); 1174 int screenBottom = screenTop + height; 1175 1176 int fadingEdge = getVerticalFadingEdgeLength(); 1177 1178 // leave room for top fading edge as long as rect isn't at very top 1179 if (rect.top > 0) { 1180 screenTop += fadingEdge; 1181 } 1182 1183 // leave room for bottom fading edge as long as rect isn't at very bottom 1184 if (rect.bottom < getChildAt(0).getHeight()) { 1185 screenBottom -= fadingEdge; 1186 } 1187 1188 int scrollYDelta = 0; 1189 1190 if (rect.bottom > screenBottom && rect.top > screenTop) { 1191 // need to move down to get it in view: move down just enough so 1192 // that the entire rectangle is in view (or at least the first 1193 // screen size chunk). 1194 1195 if (rect.height() > height) { 1196 // just enough to get screen size chunk on 1197 scrollYDelta += (rect.top - screenTop); 1198 } else { 1199 // get entire rect at bottom of screen 1200 scrollYDelta += (rect.bottom - screenBottom); 1201 } 1202 1203 // make sure we aren't scrolling beyond the end of our content 1204 int bottom = getChildAt(0).getBottom(); 1205 int distanceToBottom = bottom - screenBottom; 1206 scrollYDelta = Math.min(scrollYDelta, distanceToBottom); 1207 1208 } else if (rect.top < screenTop && rect.bottom < screenBottom) { 1209 // need to move up to get it in view: move up just enough so that 1210 // entire rectangle is in view (or at least the first screen 1211 // size chunk of it). 1212 1213 if (rect.height() > height) { 1214 // screen size chunk 1215 scrollYDelta -= (screenBottom - rect.bottom); 1216 } else { 1217 // entire rect at top 1218 scrollYDelta -= (screenTop - rect.top); 1219 } 1220 1221 // make sure we aren't scrolling any further than the top our content 1222 scrollYDelta = Math.max(scrollYDelta, -getScrollY()); 1223 } 1224 return scrollYDelta; 1225 } 1226 1227 @Override 1228 public void requestChildFocus(View child, View focused) { 1229 if (!mScrollViewMovedFocus) { 1230 if (!mIsLayoutDirty) { 1231 scrollToChild(focused); 1232 } else { 1233 // The child may not be laid out yet, we can't compute the scroll yet 1234 mChildToScrollTo = focused; 1235 } 1236 } 1237 super.requestChildFocus(child, focused); 1238 } 1239 1240 1241 /** 1242 * When looking for focus in children of a scroll view, need to be a little 1243 * more careful not to give focus to something that is scrolled off screen. 1244 * 1245 * This is more expensive than the default {@link android.view.ViewGroup} 1246 * implementation, otherwise this behavior might have been made the default. 1247 */ 1248 @Override 1249 protected boolean onRequestFocusInDescendants(int direction, 1250 Rect previouslyFocusedRect) { 1251 1252 // convert from forward / backward notation to up / down / left / right 1253 // (ugh). 1254 if (direction == View.FOCUS_FORWARD) { 1255 direction = View.FOCUS_DOWN; 1256 } else if (direction == View.FOCUS_BACKWARD) { 1257 direction = View.FOCUS_UP; 1258 } 1259 1260 final View nextFocus = previouslyFocusedRect == null ? 1261 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1262 FocusFinder.getInstance().findNextFocusFromRect(this, 1263 previouslyFocusedRect, direction); 1264 1265 if (nextFocus == null) { 1266 return false; 1267 } 1268 1269 if (isOffScreen(nextFocus)) { 1270 return false; 1271 } 1272 1273 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1274 } 1275 1276 @Override 1277 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1278 boolean immediate) { 1279 // offset into coordinate space of this scroll view 1280 rectangle.offset(child.getLeft() - child.getScrollX(), 1281 child.getTop() - child.getScrollY()); 1282 1283 return scrollToChildRect(rectangle, immediate); 1284 } 1285 1286 @Override 1287 public void requestLayout() { 1288 mIsLayoutDirty = true; 1289 super.requestLayout(); 1290 } 1291 1292 @Override 1293 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1294 super.onLayout(changed, l, t, r, b); 1295 mIsLayoutDirty = false; 1296 // Give a child focus if it needs it 1297 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1298 scrollToChild(mChildToScrollTo); 1299 } 1300 mChildToScrollTo = null; 1301 1302 // Calling this with the present values causes it to re-clam them 1303 scrollTo(mScrollX, mScrollY); 1304 } 1305 1306 @Override 1307 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1308 super.onSizeChanged(w, h, oldw, oldh); 1309 1310 View currentFocused = findFocus(); 1311 if (null == currentFocused || this == currentFocused) 1312 return; 1313 1314 // If the currently-focused view was visible on the screen when the 1315 // screen was at the old height, then scroll the screen to make that 1316 // view visible with the new screen height. 1317 if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { 1318 currentFocused.getDrawingRect(mTempRect); 1319 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1320 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1321 doScrollY(scrollDelta); 1322 } 1323 } 1324 1325 /** 1326 * Return true if child is an descendant of parent, (or equal to the parent). 1327 */ 1328 private boolean isViewDescendantOf(View child, View parent) { 1329 if (child == parent) { 1330 return true; 1331 } 1332 1333 final ViewParent theParent = child.getParent(); 1334 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1335 } 1336 1337 /** 1338 * Fling the scroll view 1339 * 1340 * @param velocityY The initial velocity in the Y direction. Positive 1341 * numbers mean that the finger/cursor is moving down the screen, 1342 * which means we want to scroll towards the top. 1343 */ 1344 public void fling(int velocityY) { 1345 if (getChildCount() > 0) { 1346 int height = getHeight() - mPaddingBottom - mPaddingTop; 1347 int bottom = getChildAt(0).getHeight(); 1348 1349 mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0, 1350 Math.max(0, bottom - height), 0, height/2); 1351 1352 final boolean movingDown = velocityY > 0; 1353 1354 View newFocused = 1355 findFocusableViewInMyBounds(movingDown, mScroller.getFinalY(), findFocus()); 1356 if (newFocused == null) { 1357 newFocused = this; 1358 } 1359 1360 if (newFocused != findFocus() 1361 && newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : View.FOCUS_UP)) { 1362 mScrollViewMovedFocus = true; 1363 mScrollViewMovedFocus = false; 1364 } 1365 1366 invalidate(); 1367 } 1368 } 1369 1370 /** 1371 * {@inheritDoc} 1372 * 1373 * <p>This version also clamps the scrolling to the bounds of our child. 1374 */ 1375 @Override 1376 public void scrollTo(int x, int y) { 1377 // we rely on the fact the View.scrollBy calls scrollTo. 1378 if (getChildCount() > 0) { 1379 View child = getChildAt(0); 1380 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1381 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1382 if (x != mScrollX || y != mScrollY) { 1383 super.scrollTo(x, y); 1384 } 1385 } 1386 } 1387 1388 @Override 1389 public void setOverScrollMode(int mode) { 1390 if (mode != OVER_SCROLL_NEVER) { 1391 if (mEdgeGlowTop == null) { 1392 final Resources res = getContext().getResources(); 1393 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1394 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1395 mEdgeGlowTop = new EdgeGlow(edge, glow); 1396 mEdgeGlowBottom = new EdgeGlow(edge, glow); 1397 } 1398 } else { 1399 mEdgeGlowTop = null; 1400 mEdgeGlowBottom = null; 1401 } 1402 super.setOverScrollMode(mode); 1403 } 1404 1405 @Override 1406 public void draw(Canvas canvas) { 1407 super.draw(canvas); 1408 if (mEdgeGlowTop != null) { 1409 final int scrollY = mScrollY; 1410 if (!mEdgeGlowTop.isFinished()) { 1411 final int restoreCount = canvas.save(); 1412 final int width = getWidth(); 1413 1414 canvas.translate(-width / 2, Math.min(0, scrollY)); 1415 mEdgeGlowTop.setSize(width * 2, getHeight()); 1416 if (mEdgeGlowTop.draw(canvas)) { 1417 invalidate(); 1418 } 1419 canvas.restoreToCount(restoreCount); 1420 } 1421 if (!mEdgeGlowBottom.isFinished()) { 1422 final int restoreCount = canvas.save(); 1423 final int width = getWidth(); 1424 final int height = getHeight(); 1425 1426 canvas.translate(-width / 2, Math.max(getScrollRange(), scrollY) + height); 1427 canvas.rotate(180, width, 0); 1428 mEdgeGlowBottom.setSize(width * 2, height); 1429 if (mEdgeGlowBottom.draw(canvas)) { 1430 invalidate(); 1431 } 1432 canvas.restoreToCount(restoreCount); 1433 } 1434 } 1435 } 1436 1437 private int clamp(int n, int my, int child) { 1438 if (my >= child || n < 0) { 1439 /* my >= child is this case: 1440 * |--------------- me ---------------| 1441 * |------ child ------| 1442 * or 1443 * |--------------- me ---------------| 1444 * |------ child ------| 1445 * or 1446 * |--------------- me ---------------| 1447 * |------ child ------| 1448 * 1449 * n < 0 is this case: 1450 * |------ me ------| 1451 * |-------- child --------| 1452 * |-- mScrollX --| 1453 */ 1454 return 0; 1455 } 1456 if ((my+n) > child) { 1457 /* this case: 1458 * |------ me ------| 1459 * |------ child ------| 1460 * |-- mScrollX --| 1461 */ 1462 return child-my; 1463 } 1464 return n; 1465 } 1466 } 1467
