HorizontalScrollView.java revision a174d7a0d5475dbae2b48f7359abf1637a882896
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.widget; 18 19import android.view.ViewDebug; 20import com.android.internal.R; 21 22import android.util.AttributeSet; 23import android.graphics.Canvas; 24import android.graphics.Rect; 25import android.graphics.drawable.Drawable; 26import android.view.View; 27import android.view.VelocityTracker; 28import android.view.ViewConfiguration; 29import android.view.ViewGroup; 30import android.view.KeyEvent; 31import android.view.FocusFinder; 32import android.view.MotionEvent; 33import android.view.ViewParent; 34import android.view.animation.AnimationUtils; 35import android.content.Context; 36import android.content.res.Resources; 37import android.content.res.TypedArray; 38 39import java.util.List; 40 41/** 42 * Layout container for a view hierarchy that can be scrolled by the user, 43 * allowing it to be larger than the physical display. A HorizontalScrollView 44 * is a {@link FrameLayout}, meaning you should place one child in it 45 * containing the entire contents to scroll; this child may itself be a layout 46 * manager with a complex hierarchy of objects. A child that is often used 47 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 48 * array of top-level items that the user can scroll through. 49 * 50 * <p>You should never use a HorizontalScrollView with a {@link ListView}, since 51 * ListView takes care of its own scrolling. Most importantly, doing this 52 * defeats all of the important optimizations in ListView for dealing with 53 * large lists, since it effectively forces the ListView to display its entire 54 * list of items to fill up the infinite container supplied by HorizontalScrollView. 55 * 56 * <p>The {@link TextView} class also 57 * takes care of its own scrolling, so does not require a ScrollView, but 58 * using the two together is possible to achieve the effect of a text view 59 * within a larger container. 60 * 61 * <p>HorizontalScrollView only supports horizontal scrolling. 62 * 63 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 64 */ 65public class HorizontalScrollView extends FrameLayout { 66 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 67 68 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 69 70 71 private long mLastScroll; 72 73 private final Rect mTempRect = new Rect(); 74 private OverScroller mScroller; 75 private EdgeGlow mEdgeGlowLeft; 76 private EdgeGlow mEdgeGlowRight; 77 78 /** 79 * Flag to indicate that we are moving focus ourselves. This is so the 80 * code that watches for focus changes initiated outside this ScrollView 81 * knows that it does not have to do anything. 82 */ 83 private boolean mScrollViewMovedFocus; 84 85 /** 86 * Position of the last motion event. 87 */ 88 private float mLastMotionX; 89 90 /** 91 * True when the layout has changed but the traversal has not come through yet. 92 * Ideally the view hierarchy would keep track of this for us. 93 */ 94 private boolean mIsLayoutDirty = true; 95 96 /** 97 * The child to give focus to in the event that a child has requested focus while the 98 * layout is dirty. This prevents the scroll from being wrong if the child has not been 99 * laid out before requesting focus. 100 */ 101 private View mChildToScrollTo = null; 102 103 /** 104 * True if the user is currently dragging this ScrollView around. This is 105 * not the same as 'is being flinged', which can be checked by 106 * mScroller.isFinished() (flinging begins when the user lifts his finger). 107 */ 108 private boolean mIsBeingDragged = false; 109 110 /** 111 * Determines speed during touch scrolling 112 */ 113 private VelocityTracker mVelocityTracker; 114 115 /** 116 * When set to true, the scroll view measure its child to make it fill the currently 117 * visible area. 118 */ 119 @ViewDebug.ExportedProperty(category = "layout") 120 private boolean mFillViewport; 121 122 /** 123 * Whether arrow scrolling is animated. 124 */ 125 private boolean mSmoothScrollingEnabled = true; 126 127 private int mTouchSlop; 128 private int mMinimumVelocity; 129 private int mMaximumVelocity; 130 131 private int mOverscrollDistance; 132 private int mOverflingDistance; 133 134 /** 135 * ID of the active pointer. This is used to retain consistency during 136 * drags/flings if multiple pointers are used. 137 */ 138 private int mActivePointerId = INVALID_POINTER; 139 140 /** 141 * Sentinel value for no current active pointer. 142 * Used by {@link #mActivePointerId}. 143 */ 144 private static final int INVALID_POINTER = -1; 145 146 public HorizontalScrollView(Context context) { 147 this(context, null); 148 } 149 150 public HorizontalScrollView(Context context, AttributeSet attrs) { 151 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 152 } 153 154 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 155 super(context, attrs, defStyle); 156 initScrollView(); 157 158 TypedArray a = context.obtainStyledAttributes(attrs, 159 android.R.styleable.HorizontalScrollView, defStyle, 0); 160 161 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 162 163 a.recycle(); 164 } 165 166 @Override 167 protected float getLeftFadingEdgeStrength() { 168 if (getChildCount() == 0) { 169 return 0.0f; 170 } 171 172 final int length = getHorizontalFadingEdgeLength(); 173 if (mScrollX < length) { 174 return mScrollX / (float) length; 175 } 176 177 return 1.0f; 178 } 179 180 @Override 181 protected float getRightFadingEdgeStrength() { 182 if (getChildCount() == 0) { 183 return 0.0f; 184 } 185 186 final int length = getHorizontalFadingEdgeLength(); 187 final int rightEdge = getWidth() - mPaddingRight; 188 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 189 if (span < length) { 190 return span / (float) length; 191 } 192 193 return 1.0f; 194 } 195 196 /** 197 * @return The maximum amount this scroll view will scroll in response to 198 * an arrow event. 199 */ 200 public int getMaxScrollAmount() { 201 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 202 } 203 204 205 private void initScrollView() { 206 mScroller = new OverScroller(getContext()); 207 setFocusable(true); 208 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 209 setWillNotDraw(false); 210 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 211 mTouchSlop = configuration.getScaledTouchSlop(); 212 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 213 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 214 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 215 mOverflingDistance = configuration.getScaledOverflingDistance(); 216 } 217 218 @Override 219 public void addView(View child) { 220 if (getChildCount() > 0) { 221 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 222 } 223 224 super.addView(child); 225 } 226 227 @Override 228 public void addView(View child, int index) { 229 if (getChildCount() > 0) { 230 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 231 } 232 233 super.addView(child, index); 234 } 235 236 @Override 237 public void addView(View child, ViewGroup.LayoutParams params) { 238 if (getChildCount() > 0) { 239 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 240 } 241 242 super.addView(child, params); 243 } 244 245 @Override 246 public void addView(View child, int index, ViewGroup.LayoutParams params) { 247 if (getChildCount() > 0) { 248 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 249 } 250 251 super.addView(child, index, params); 252 } 253 254 /** 255 * @return Returns true this HorizontalScrollView can be scrolled 256 */ 257 private boolean canScroll() { 258 View child = getChildAt(0); 259 if (child != null) { 260 int childWidth = child.getWidth(); 261 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 262 } 263 return false; 264 } 265 266 /** 267 * Indicates whether this HorizontalScrollView's content is stretched to 268 * fill the viewport. 269 * 270 * @return True if the content fills the viewport, false otherwise. 271 * 272 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 273 */ 274 public boolean isFillViewport() { 275 return mFillViewport; 276 } 277 278 /** 279 * Indicates this HorizontalScrollView whether it should stretch its content width 280 * to fill the viewport or not. 281 * 282 * @param fillViewport True to stretch the content's width to the viewport's 283 * boundaries, false otherwise. 284 * 285 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 286 */ 287 public void setFillViewport(boolean fillViewport) { 288 if (fillViewport != mFillViewport) { 289 mFillViewport = fillViewport; 290 requestLayout(); 291 } 292 } 293 294 /** 295 * @return Whether arrow scrolling will animate its transition. 296 */ 297 public boolean isSmoothScrollingEnabled() { 298 return mSmoothScrollingEnabled; 299 } 300 301 /** 302 * Set whether arrow scrolling will animate its transition. 303 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 304 */ 305 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 306 mSmoothScrollingEnabled = smoothScrollingEnabled; 307 } 308 309 @Override 310 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 311 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 312 313 if (!mFillViewport) { 314 return; 315 } 316 317 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 318 if (widthMode == MeasureSpec.UNSPECIFIED) { 319 return; 320 } 321 322 if (getChildCount() > 0) { 323 final View child = getChildAt(0); 324 int width = getMeasuredWidth(); 325 if (child.getMeasuredWidth() < width) { 326 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 327 328 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 329 + mPaddingBottom, lp.height); 330 width -= mPaddingLeft; 331 width -= mPaddingRight; 332 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 333 334 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 335 } 336 } 337 } 338 339 @Override 340 public boolean dispatchKeyEvent(KeyEvent event) { 341 // Let the focused view and/or our descendants get the key first 342 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 343 } 344 345 /** 346 * You can call this function yourself to have the scroll view perform 347 * scrolling from a key event, just as if the event had been dispatched to 348 * it by the view hierarchy. 349 * 350 * @param event The key event to execute. 351 * @return Return true if the event was handled, else false. 352 */ 353 public boolean executeKeyEvent(KeyEvent event) { 354 mTempRect.setEmpty(); 355 356 if (!canScroll()) { 357 if (isFocused()) { 358 View currentFocused = findFocus(); 359 if (currentFocused == this) currentFocused = null; 360 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 361 currentFocused, View.FOCUS_RIGHT); 362 return nextFocused != null && nextFocused != this && 363 nextFocused.requestFocus(View.FOCUS_RIGHT); 364 } 365 return false; 366 } 367 368 boolean handled = false; 369 if (event.getAction() == KeyEvent.ACTION_DOWN) { 370 switch (event.getKeyCode()) { 371 case KeyEvent.KEYCODE_DPAD_LEFT: 372 if (!event.isAltPressed()) { 373 handled = arrowScroll(View.FOCUS_LEFT); 374 } else { 375 handled = fullScroll(View.FOCUS_LEFT); 376 } 377 break; 378 case KeyEvent.KEYCODE_DPAD_RIGHT: 379 if (!event.isAltPressed()) { 380 handled = arrowScroll(View.FOCUS_RIGHT); 381 } else { 382 handled = fullScroll(View.FOCUS_RIGHT); 383 } 384 break; 385 case KeyEvent.KEYCODE_SPACE: 386 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 387 break; 388 } 389 } 390 391 return handled; 392 } 393 394 private boolean inChild(int x, int y) { 395 if (getChildCount() > 0) { 396 final int scrollX = mScrollX; 397 final View child = getChildAt(0); 398 return !(y < child.getTop() 399 || y >= child.getBottom() 400 || x < child.getLeft() - scrollX 401 || x >= child.getRight() - scrollX); 402 } 403 return false; 404 } 405 406 @Override 407 public boolean onInterceptTouchEvent(MotionEvent ev) { 408 /* 409 * This method JUST determines whether we want to intercept the motion. 410 * If we return true, onMotionEvent will be called and we do the actual 411 * scrolling there. 412 */ 413 414 /* 415 * Shortcut the most recurring case: the user is in the dragging 416 * state and he is moving his finger. We want to intercept this 417 * motion. 418 */ 419 final int action = ev.getAction(); 420 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 421 return true; 422 } 423 424 switch (action & MotionEvent.ACTION_MASK) { 425 case MotionEvent.ACTION_MOVE: { 426 /* 427 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 428 * whether the user has moved far enough from his original down touch. 429 */ 430 431 /* 432 * Locally do absolute value. mLastMotionX is set to the x value 433 * of the down event. 434 */ 435 final int activePointerId = mActivePointerId; 436 if (activePointerId == INVALID_POINTER) { 437 // If we don't have a valid id, the touch down wasn't on content. 438 break; 439 } 440 441 final int pointerIndex = ev.findPointerIndex(activePointerId); 442 final float x = ev.getX(pointerIndex); 443 final int xDiff = (int) Math.abs(x - mLastMotionX); 444 if (xDiff > mTouchSlop) { 445 mIsBeingDragged = true; 446 mLastMotionX = x; 447 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 448 } 449 break; 450 } 451 452 case MotionEvent.ACTION_DOWN: { 453 final float x = ev.getX(); 454 if (!inChild((int) x, (int) ev.getY())) { 455 mIsBeingDragged = false; 456 break; 457 } 458 459 /* 460 * Remember location of down touch. 461 * ACTION_DOWN always refers to pointer index 0. 462 */ 463 mLastMotionX = x; 464 mActivePointerId = ev.getPointerId(0); 465 466 /* 467 * If being flinged and user touches the screen, initiate drag; 468 * otherwise don't. mScroller.isFinished should be false when 469 * being flinged. 470 */ 471 mIsBeingDragged = !mScroller.isFinished(); 472 break; 473 } 474 475 case MotionEvent.ACTION_CANCEL: 476 case MotionEvent.ACTION_UP: 477 /* Release the drag */ 478 mIsBeingDragged = false; 479 mActivePointerId = INVALID_POINTER; 480 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 481 invalidate(); 482 } 483 break; 484 case MotionEvent.ACTION_POINTER_UP: 485 onSecondaryPointerUp(ev); 486 break; 487 } 488 489 /* 490 * The only time we want to intercept motion events is if we are in the 491 * drag mode. 492 */ 493 return mIsBeingDragged; 494 } 495 496 @Override 497 public boolean onTouchEvent(MotionEvent ev) { 498 499 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 500 // Don't handle edge touches immediately -- they may actually belong to one of our 501 // descendants. 502 return false; 503 } 504 505 if (mVelocityTracker == null) { 506 mVelocityTracker = VelocityTracker.obtain(); 507 } 508 mVelocityTracker.addMovement(ev); 509 510 final int action = ev.getAction(); 511 512 switch (action & MotionEvent.ACTION_MASK) { 513 case MotionEvent.ACTION_DOWN: { 514 final float x = ev.getX(); 515 mIsBeingDragged = true; 516 517 /* 518 * If being flinged and user touches, stop the fling. isFinished 519 * will be false if being flinged. 520 */ 521 if (!mScroller.isFinished()) { 522 mScroller.abortAnimation(); 523 } 524 525 // Remember where the motion event started 526 mLastMotionX = x; 527 mActivePointerId = ev.getPointerId(0); 528 break; 529 } 530 case MotionEvent.ACTION_MOVE: 531 if (mIsBeingDragged) { 532 // Scroll to follow the motion event 533 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 534 final float x = ev.getX(activePointerIndex); 535 final int deltaX = (int) (mLastMotionX - x); 536 mLastMotionX = x; 537 538 final int oldX = mScrollX; 539 final int oldY = mScrollY; 540 final int range = getScrollRange(); 541 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 542 mOverscrollDistance, 0, true)) { 543 // Break our velocity if we hit a scroll barrier. 544 mVelocityTracker.clear(); 545 } 546 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 547 548 final int overscrollMode = getOverScrollMode(); 549 if (overscrollMode == OVER_SCROLL_ALWAYS || 550 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 551 final int pulledToX = oldX + deltaX; 552 if (pulledToX < 0) { 553 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 554 if (!mEdgeGlowRight.isFinished()) { 555 mEdgeGlowRight.onRelease(); 556 } 557 } else if (pulledToX > range) { 558 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 559 if (!mEdgeGlowLeft.isFinished()) { 560 mEdgeGlowLeft.onRelease(); 561 } 562 } 563 if (mEdgeGlowLeft != null 564 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 565 invalidate(); 566 } 567 } 568 } 569 break; 570 case MotionEvent.ACTION_UP: 571 if (mIsBeingDragged) { 572 final VelocityTracker velocityTracker = mVelocityTracker; 573 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 574 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 575 576 if (getChildCount() > 0) { 577 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 578 fling(-initialVelocity); 579 } else { 580 final int right = getScrollRange(); 581 if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { 582 invalidate(); 583 } 584 } 585 } 586 587 mActivePointerId = INVALID_POINTER; 588 mIsBeingDragged = false; 589 590 if (mVelocityTracker != null) { 591 mVelocityTracker.recycle(); 592 mVelocityTracker = null; 593 } 594 if (mEdgeGlowLeft != null) { 595 mEdgeGlowLeft.onRelease(); 596 mEdgeGlowRight.onRelease(); 597 } 598 } 599 break; 600 case MotionEvent.ACTION_CANCEL: 601 if (mIsBeingDragged && getChildCount() > 0) { 602 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 603 invalidate(); 604 } 605 mActivePointerId = INVALID_POINTER; 606 mIsBeingDragged = false; 607 if (mVelocityTracker != null) { 608 mVelocityTracker.recycle(); 609 mVelocityTracker = null; 610 } 611 if (mEdgeGlowLeft != null) { 612 mEdgeGlowLeft.onRelease(); 613 mEdgeGlowRight.onRelease(); 614 } 615 } 616 break; 617 case MotionEvent.ACTION_POINTER_UP: 618 onSecondaryPointerUp(ev); 619 break; 620 } 621 return true; 622 } 623 624 private void onSecondaryPointerUp(MotionEvent ev) { 625 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 626 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 627 final int pointerId = ev.getPointerId(pointerIndex); 628 if (pointerId == mActivePointerId) { 629 // This was our active pointer going up. Choose a new 630 // active pointer and adjust accordingly. 631 // TODO: Make this decision more intelligent. 632 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 633 mLastMotionX = ev.getX(newPointerIndex); 634 mActivePointerId = ev.getPointerId(newPointerIndex); 635 if (mVelocityTracker != null) { 636 mVelocityTracker.clear(); 637 } 638 } 639 } 640 641 @Override 642 protected void onOverScrolled(int scrollX, int scrollY, 643 boolean clampedX, boolean clampedY) { 644 // Treat animating scrolls differently; see #computeScroll() for why. 645 if (!mScroller.isFinished()) { 646 mScrollX = scrollX; 647 mScrollY = scrollY; 648 if (clampedX) { 649 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 650 } 651 } else { 652 super.scrollTo(scrollX, scrollY); 653 } 654 awakenScrollBars(); 655 } 656 657 private int getScrollRange() { 658 int scrollRange = 0; 659 if (getChildCount() > 0) { 660 View child = getChildAt(0); 661 scrollRange = Math.max(0, 662 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 663 } 664 return scrollRange; 665 } 666 667 /** 668 * <p> 669 * Finds the next focusable component that fits in this View's bounds 670 * (excluding fading edges) pretending that this View's left is located at 671 * the parameter left. 672 * </p> 673 * 674 * @param leftFocus look for a candidate is the one at the left of the bounds 675 * if leftFocus is true, or at the right of the bounds if leftFocus 676 * is false 677 * @param left the left offset of the bounds in which a focusable must be 678 * found (the fading edge is assumed to start at this position) 679 * @param preferredFocusable the View that has highest priority and will be 680 * returned if it is within my bounds (null is valid) 681 * @return the next focusable component in the bounds or null if none can be found 682 */ 683 private View findFocusableViewInMyBounds(final boolean leftFocus, 684 final int left, View preferredFocusable) { 685 /* 686 * The fading edge's transparent side should be considered for focus 687 * since it's mostly visible, so we divide the actual fading edge length 688 * by 2. 689 */ 690 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 691 final int leftWithoutFadingEdge = left + fadingEdgeLength; 692 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 693 694 if ((preferredFocusable != null) 695 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 696 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 697 return preferredFocusable; 698 } 699 700 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 701 rightWithoutFadingEdge); 702 } 703 704 /** 705 * <p> 706 * Finds the next focusable component that fits in the specified bounds. 707 * </p> 708 * 709 * @param leftFocus look for a candidate is the one at the left of the bounds 710 * if leftFocus is true, or at the right of the bounds if 711 * leftFocus is false 712 * @param left the left offset of the bounds in which a focusable must be 713 * found 714 * @param right the right offset of the bounds in which a focusable must 715 * be found 716 * @return the next focusable component in the bounds or null if none can 717 * be found 718 */ 719 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 720 721 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 722 View focusCandidate = null; 723 724 /* 725 * A fully contained focusable is one where its left is below the bound's 726 * left, and its right is above the bound's right. A partially 727 * contained focusable is one where some part of it is within the 728 * bounds, but it also has some part that is not within bounds. A fully contained 729 * focusable is preferred to a partially contained focusable. 730 */ 731 boolean foundFullyContainedFocusable = false; 732 733 int count = focusables.size(); 734 for (int i = 0; i < count; i++) { 735 View view = focusables.get(i); 736 int viewLeft = view.getLeft(); 737 int viewRight = view.getRight(); 738 739 if (left < viewRight && viewLeft < right) { 740 /* 741 * the focusable is in the target area, it is a candidate for 742 * focusing 743 */ 744 745 final boolean viewIsFullyContained = (left < viewLeft) && 746 (viewRight < right); 747 748 if (focusCandidate == null) { 749 /* No candidate, take this one */ 750 focusCandidate = view; 751 foundFullyContainedFocusable = viewIsFullyContained; 752 } else { 753 final boolean viewIsCloserToBoundary = 754 (leftFocus && viewLeft < focusCandidate.getLeft()) || 755 (!leftFocus && viewRight > focusCandidate.getRight()); 756 757 if (foundFullyContainedFocusable) { 758 if (viewIsFullyContained && viewIsCloserToBoundary) { 759 /* 760 * We're dealing with only fully contained views, so 761 * it has to be closer to the boundary to beat our 762 * candidate 763 */ 764 focusCandidate = view; 765 } 766 } else { 767 if (viewIsFullyContained) { 768 /* Any fully contained view beats a partially contained view */ 769 focusCandidate = view; 770 foundFullyContainedFocusable = true; 771 } else if (viewIsCloserToBoundary) { 772 /* 773 * Partially contained view beats another partially 774 * contained view if it's closer 775 */ 776 focusCandidate = view; 777 } 778 } 779 } 780 } 781 } 782 783 return focusCandidate; 784 } 785 786 /** 787 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 788 * method will scroll the view by one page left or right and give the focus 789 * to the leftmost/rightmost component in the new visible area. If no 790 * component is a good candidate for focus, this scrollview reclaims the 791 * focus.</p> 792 * 793 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 794 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 795 * to go one page right 796 * @return true if the key event is consumed by this method, false otherwise 797 */ 798 public boolean pageScroll(int direction) { 799 boolean right = direction == View.FOCUS_RIGHT; 800 int width = getWidth(); 801 802 if (right) { 803 mTempRect.left = getScrollX() + width; 804 int count = getChildCount(); 805 if (count > 0) { 806 View view = getChildAt(0); 807 if (mTempRect.left + width > view.getRight()) { 808 mTempRect.left = view.getRight() - width; 809 } 810 } 811 } else { 812 mTempRect.left = getScrollX() - width; 813 if (mTempRect.left < 0) { 814 mTempRect.left = 0; 815 } 816 } 817 mTempRect.right = mTempRect.left + width; 818 819 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 820 } 821 822 /** 823 * <p>Handles scrolling in response to a "home/end" shortcut press. This 824 * method will scroll the view to the left or right and give the focus 825 * to the leftmost/rightmost component in the new visible area. If no 826 * component is a good candidate for focus, this scrollview reclaims the 827 * focus.</p> 828 * 829 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 830 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 831 * to go the right 832 * @return true if the key event is consumed by this method, false otherwise 833 */ 834 public boolean fullScroll(int direction) { 835 boolean right = direction == View.FOCUS_RIGHT; 836 int width = getWidth(); 837 838 mTempRect.left = 0; 839 mTempRect.right = width; 840 841 if (right) { 842 int count = getChildCount(); 843 if (count > 0) { 844 View view = getChildAt(0); 845 mTempRect.right = view.getRight(); 846 mTempRect.left = mTempRect.right - width; 847 } 848 } 849 850 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 851 } 852 853 /** 854 * <p>Scrolls the view to make the area defined by <code>left</code> and 855 * <code>right</code> visible. This method attempts to give the focus 856 * to a component visible in this area. If no component can be focused in 857 * the new visible area, the focus is reclaimed by this scrollview.</p> 858 * 859 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 860 * to go left {@link android.view.View#FOCUS_RIGHT} to right 861 * @param left the left offset of the new area to be made visible 862 * @param right the right offset of the new area to be made visible 863 * @return true if the key event is consumed by this method, false otherwise 864 */ 865 private boolean scrollAndFocus(int direction, int left, int right) { 866 boolean handled = true; 867 868 int width = getWidth(); 869 int containerLeft = getScrollX(); 870 int containerRight = containerLeft + width; 871 boolean goLeft = direction == View.FOCUS_LEFT; 872 873 View newFocused = findFocusableViewInBounds(goLeft, left, right); 874 if (newFocused == null) { 875 newFocused = this; 876 } 877 878 if (left >= containerLeft && right <= containerRight) { 879 handled = false; 880 } else { 881 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 882 doScrollX(delta); 883 } 884 885 if (newFocused != findFocus() && newFocused.requestFocus(direction)) { 886 mScrollViewMovedFocus = true; 887 mScrollViewMovedFocus = false; 888 } 889 890 return handled; 891 } 892 893 /** 894 * Handle scrolling in response to a left or right arrow click. 895 * 896 * @param direction The direction corresponding to the arrow key that was 897 * pressed 898 * @return True if we consumed the event, false otherwise 899 */ 900 public boolean arrowScroll(int direction) { 901 902 View currentFocused = findFocus(); 903 if (currentFocused == this) currentFocused = null; 904 905 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 906 907 final int maxJump = getMaxScrollAmount(); 908 909 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 910 nextFocused.getDrawingRect(mTempRect); 911 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 912 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 913 doScrollX(scrollDelta); 914 nextFocused.requestFocus(direction); 915 } else { 916 // no new focus 917 int scrollDelta = maxJump; 918 919 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 920 scrollDelta = getScrollX(); 921 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 922 923 int daRight = getChildAt(0).getRight(); 924 925 int screenRight = getScrollX() + getWidth(); 926 927 if (daRight - screenRight < maxJump) { 928 scrollDelta = daRight - screenRight; 929 } 930 } 931 if (scrollDelta == 0) { 932 return false; 933 } 934 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 935 } 936 937 if (currentFocused != null && currentFocused.isFocused() 938 && isOffScreen(currentFocused)) { 939 // previously focused item still has focus and is off screen, give 940 // it up (take it back to ourselves) 941 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 942 // sure to 943 // get it) 944 final int descendantFocusability = getDescendantFocusability(); // save 945 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 946 requestFocus(); 947 setDescendantFocusability(descendantFocusability); // restore 948 } 949 return true; 950 } 951 952 /** 953 * @return whether the descendant of this scroll view is scrolled off 954 * screen. 955 */ 956 private boolean isOffScreen(View descendant) { 957 return !isWithinDeltaOfScreen(descendant, 0); 958 } 959 960 /** 961 * @return whether the descendant of this scroll view is within delta 962 * pixels of being on the screen. 963 */ 964 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 965 descendant.getDrawingRect(mTempRect); 966 offsetDescendantRectToMyCoords(descendant, mTempRect); 967 968 return (mTempRect.right + delta) >= getScrollX() 969 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 970 } 971 972 /** 973 * Smooth scroll by a X delta 974 * 975 * @param delta the number of pixels to scroll by on the X axis 976 */ 977 private void doScrollX(int delta) { 978 if (delta != 0) { 979 if (mSmoothScrollingEnabled) { 980 smoothScrollBy(delta, 0); 981 } else { 982 scrollBy(delta, 0); 983 } 984 } 985 } 986 987 /** 988 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 989 * 990 * @param dx the number of pixels to scroll by on the X axis 991 * @param dy the number of pixels to scroll by on the Y axis 992 */ 993 public final void smoothScrollBy(int dx, int dy) { 994 if (getChildCount() == 0) { 995 // Nothing to do. 996 return; 997 } 998 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 999 if (duration > ANIMATED_SCROLL_GAP) { 1000 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1001 final int right = getChildAt(0).getWidth(); 1002 final int maxX = Math.max(0, right - width); 1003 final int scrollX = mScrollX; 1004 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1005 1006 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1007 invalidate(); 1008 } else { 1009 if (!mScroller.isFinished()) { 1010 mScroller.abortAnimation(); 1011 } 1012 scrollBy(dx, dy); 1013 } 1014 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1015 } 1016 1017 /** 1018 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1019 * 1020 * @param x the position where to scroll on the X axis 1021 * @param y the position where to scroll on the Y axis 1022 */ 1023 public final void smoothScrollTo(int x, int y) { 1024 smoothScrollBy(x - mScrollX, y - mScrollY); 1025 } 1026 1027 /** 1028 * <p>The scroll range of a scroll view is the overall width of all of its 1029 * children.</p> 1030 */ 1031 @Override 1032 protected int computeHorizontalScrollRange() { 1033 final int count = getChildCount(); 1034 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1035 if (count == 0) { 1036 return contentWidth; 1037 } 1038 1039 int scrollRange = getChildAt(0).getRight(); 1040 final int scrollX = mScrollX; 1041 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1042 if (scrollX < 0) { 1043 scrollRange -= scrollX; 1044 } else if (scrollX > overscrollRight) { 1045 scrollRange += scrollX - overscrollRight; 1046 } 1047 1048 return scrollRange; 1049 } 1050 1051 @Override 1052 protected int computeHorizontalScrollOffset() { 1053 return Math.max(0, super.computeHorizontalScrollOffset()); 1054 } 1055 1056 @Override 1057 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1058 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1059 1060 int childWidthMeasureSpec; 1061 int childHeightMeasureSpec; 1062 1063 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1064 + mPaddingBottom, lp.height); 1065 1066 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1067 1068 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1069 } 1070 1071 @Override 1072 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1073 int parentHeightMeasureSpec, int heightUsed) { 1074 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1075 1076 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1077 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1078 + heightUsed, lp.height); 1079 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1080 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1081 1082 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1083 } 1084 1085 @Override 1086 public void computeScroll() { 1087 if (mScroller.computeScrollOffset()) { 1088 // This is called at drawing time by ViewGroup. We don't want to 1089 // re-show the scrollbars at this point, which scrollTo will do, 1090 // so we replicate most of scrollTo here. 1091 // 1092 // It's a little odd to call onScrollChanged from inside the drawing. 1093 // 1094 // It is, except when you remember that computeScroll() is used to 1095 // animate scrolling. So unless we want to defer the onScrollChanged() 1096 // until the end of the animated scrolling, we don't really have a 1097 // choice here. 1098 // 1099 // I agree. The alternative, which I think would be worse, is to post 1100 // something and tell the subclasses later. This is bad because there 1101 // will be a window where mScrollX/Y is different from what the app 1102 // thinks it is. 1103 // 1104 int oldX = mScrollX; 1105 int oldY = mScrollY; 1106 int x = mScroller.getCurrX(); 1107 int y = mScroller.getCurrY(); 1108 1109 if (oldX != x || oldY != y) { 1110 overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, 1111 mOverflingDistance, 0, false); 1112 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1113 1114 final int range = getScrollRange(); 1115 final int overscrollMode = getOverScrollMode(); 1116 if (overscrollMode == OVER_SCROLL_ALWAYS || 1117 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1118 if (x < 0 && oldX >= 0) { 1119 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1120 } else if (x > range && oldX <= range) { 1121 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1122 } 1123 } 1124 } 1125 awakenScrollBars(); 1126 1127 // Keep on drawing until the animation has finished. 1128 postInvalidate(); 1129 } 1130 } 1131 1132 /** 1133 * Scrolls the view to the given child. 1134 * 1135 * @param child the View to scroll to 1136 */ 1137 private void scrollToChild(View child) { 1138 child.getDrawingRect(mTempRect); 1139 1140 /* Offset from child's local coordinates to ScrollView coordinates */ 1141 offsetDescendantRectToMyCoords(child, mTempRect); 1142 1143 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1144 1145 if (scrollDelta != 0) { 1146 scrollBy(scrollDelta, 0); 1147 } 1148 } 1149 1150 /** 1151 * If rect is off screen, scroll just enough to get it (or at least the 1152 * first screen size chunk of it) on screen. 1153 * 1154 * @param rect The rectangle. 1155 * @param immediate True to scroll immediately without animation 1156 * @return true if scrolling was performed 1157 */ 1158 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1159 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1160 final boolean scroll = delta != 0; 1161 if (scroll) { 1162 if (immediate) { 1163 scrollBy(delta, 0); 1164 } else { 1165 smoothScrollBy(delta, 0); 1166 } 1167 } 1168 return scroll; 1169 } 1170 1171 /** 1172 * Compute the amount to scroll in the X direction in order to get 1173 * a rectangle completely on the screen (or, if taller than the screen, 1174 * at least the first screen size chunk of it). 1175 * 1176 * @param rect The rect. 1177 * @return The scroll delta. 1178 */ 1179 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1180 if (getChildCount() == 0) return 0; 1181 1182 int width = getWidth(); 1183 int screenLeft = getScrollX(); 1184 int screenRight = screenLeft + width; 1185 1186 int fadingEdge = getHorizontalFadingEdgeLength(); 1187 1188 // leave room for left fading edge as long as rect isn't at very left 1189 if (rect.left > 0) { 1190 screenLeft += fadingEdge; 1191 } 1192 1193 // leave room for right fading edge as long as rect isn't at very right 1194 if (rect.right < getChildAt(0).getWidth()) { 1195 screenRight -= fadingEdge; 1196 } 1197 1198 int scrollXDelta = 0; 1199 1200 if (rect.right > screenRight && rect.left > screenLeft) { 1201 // need to move right to get it in view: move right just enough so 1202 // that the entire rectangle is in view (or at least the first 1203 // screen size chunk). 1204 1205 if (rect.width() > width) { 1206 // just enough to get screen size chunk on 1207 scrollXDelta += (rect.left - screenLeft); 1208 } else { 1209 // get entire rect at right of screen 1210 scrollXDelta += (rect.right - screenRight); 1211 } 1212 1213 // make sure we aren't scrolling beyond the end of our content 1214 int right = getChildAt(0).getRight(); 1215 int distanceToRight = right - screenRight; 1216 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1217 1218 } else if (rect.left < screenLeft && rect.right < screenRight) { 1219 // need to move right to get it in view: move right just enough so that 1220 // entire rectangle is in view (or at least the first screen 1221 // size chunk of it). 1222 1223 if (rect.width() > width) { 1224 // screen size chunk 1225 scrollXDelta -= (screenRight - rect.right); 1226 } else { 1227 // entire rect at left 1228 scrollXDelta -= (screenLeft - rect.left); 1229 } 1230 1231 // make sure we aren't scrolling any further than the left our content 1232 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1233 } 1234 return scrollXDelta; 1235 } 1236 1237 @Override 1238 public void requestChildFocus(View child, View focused) { 1239 if (!mScrollViewMovedFocus) { 1240 if (!mIsLayoutDirty) { 1241 scrollToChild(focused); 1242 } else { 1243 // The child may not be laid out yet, we can't compute the scroll yet 1244 mChildToScrollTo = focused; 1245 } 1246 } 1247 super.requestChildFocus(child, focused); 1248 } 1249 1250 1251 /** 1252 * When looking for focus in children of a scroll view, need to be a little 1253 * more careful not to give focus to something that is scrolled off screen. 1254 * 1255 * This is more expensive than the default {@link android.view.ViewGroup} 1256 * implementation, otherwise this behavior might have been made the default. 1257 */ 1258 @Override 1259 protected boolean onRequestFocusInDescendants(int direction, 1260 Rect previouslyFocusedRect) { 1261 1262 // convert from forward / backward notation to up / down / left / right 1263 // (ugh). 1264 if (direction == View.FOCUS_FORWARD) { 1265 direction = View.FOCUS_RIGHT; 1266 } else if (direction == View.FOCUS_BACKWARD) { 1267 direction = View.FOCUS_LEFT; 1268 } 1269 1270 final View nextFocus = previouslyFocusedRect == null ? 1271 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1272 FocusFinder.getInstance().findNextFocusFromRect(this, 1273 previouslyFocusedRect, direction); 1274 1275 if (nextFocus == null) { 1276 return false; 1277 } 1278 1279 if (isOffScreen(nextFocus)) { 1280 return false; 1281 } 1282 1283 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1284 } 1285 1286 @Override 1287 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1288 boolean immediate) { 1289 // offset into coordinate space of this scroll view 1290 rectangle.offset(child.getLeft() - child.getScrollX(), 1291 child.getTop() - child.getScrollY()); 1292 1293 return scrollToChildRect(rectangle, immediate); 1294 } 1295 1296 @Override 1297 public void requestLayout() { 1298 mIsLayoutDirty = true; 1299 super.requestLayout(); 1300 } 1301 1302 @Override 1303 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1304 super.onLayout(changed, l, t, r, b); 1305 mIsLayoutDirty = false; 1306 // Give a child focus if it needs it 1307 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1308 scrollToChild(mChildToScrollTo); 1309 } 1310 mChildToScrollTo = null; 1311 1312 // Calling this with the present values causes it to re-clam them 1313 scrollTo(mScrollX, mScrollY); 1314 } 1315 1316 @Override 1317 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1318 super.onSizeChanged(w, h, oldw, oldh); 1319 1320 View currentFocused = findFocus(); 1321 if (null == currentFocused || this == currentFocused) 1322 return; 1323 1324 final int maxJump = mRight - mLeft; 1325 1326 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1327 currentFocused.getDrawingRect(mTempRect); 1328 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1329 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1330 doScrollX(scrollDelta); 1331 } 1332 } 1333 1334 /** 1335 * Return true if child is an descendant of parent, (or equal to the parent). 1336 */ 1337 private boolean isViewDescendantOf(View child, View parent) { 1338 if (child == parent) { 1339 return true; 1340 } 1341 1342 final ViewParent theParent = child.getParent(); 1343 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1344 } 1345 1346 /** 1347 * Fling the scroll view 1348 * 1349 * @param velocityX The initial velocity in the X direction. Positive 1350 * numbers mean that the finger/curor is moving down the screen, 1351 * which means we want to scroll towards the left. 1352 */ 1353 public void fling(int velocityX) { 1354 if (getChildCount() > 0) { 1355 int width = getWidth() - mPaddingRight - mPaddingLeft; 1356 int right = getChildAt(0).getWidth(); 1357 1358 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1359 Math.max(0, right - width), 0, 0, width/2, 0); 1360 1361 final boolean movingRight = velocityX > 0; 1362 1363 View newFocused = findFocusableViewInMyBounds(movingRight, 1364 mScroller.getFinalX(), findFocus()); 1365 1366 if (newFocused == null) { 1367 newFocused = this; 1368 } 1369 1370 if (newFocused != findFocus() 1371 && newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT)) { 1372 mScrollViewMovedFocus = true; 1373 mScrollViewMovedFocus = false; 1374 } 1375 1376 invalidate(); 1377 } 1378 } 1379 1380 /** 1381 * {@inheritDoc} 1382 * 1383 * <p>This version also clamps the scrolling to the bounds of our child. 1384 */ 1385 public void scrollTo(int x, int y) { 1386 // we rely on the fact the View.scrollBy calls scrollTo. 1387 if (getChildCount() > 0) { 1388 View child = getChildAt(0); 1389 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1390 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1391 if (x != mScrollX || y != mScrollY) { 1392 super.scrollTo(x, y); 1393 } 1394 } 1395 } 1396 1397 @Override 1398 public void setOverScrollMode(int mode) { 1399 if (mode != OVER_SCROLL_NEVER) { 1400 if (mEdgeGlowLeft == null) { 1401 Context context = getContext(); 1402 final Resources res = context.getResources(); 1403 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1404 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1405 mEdgeGlowLeft = new EdgeGlow(context, edge, glow); 1406 mEdgeGlowRight = new EdgeGlow(context, edge, glow); 1407 } 1408 } else { 1409 mEdgeGlowLeft = null; 1410 mEdgeGlowRight = null; 1411 } 1412 super.setOverScrollMode(mode); 1413 } 1414 1415 @Override 1416 public void draw(Canvas canvas) { 1417 super.draw(canvas); 1418 if (mEdgeGlowLeft != null) { 1419 final int scrollX = mScrollX; 1420 if (!mEdgeGlowLeft.isFinished()) { 1421 final int restoreCount = canvas.save(); 1422 final int height = getHeight(); 1423 1424 canvas.rotate(270); 1425 canvas.translate(-height, Math.min(0, scrollX)); 1426 mEdgeGlowLeft.setSize(getHeight(), getWidth()); 1427 if (mEdgeGlowLeft.draw(canvas)) { 1428 invalidate(); 1429 } 1430 canvas.restoreToCount(restoreCount); 1431 } 1432 if (!mEdgeGlowRight.isFinished()) { 1433 final int restoreCount = canvas.save(); 1434 final int width = getWidth(); 1435 final int height = getHeight(); 1436 1437 canvas.rotate(90); 1438 canvas.translate(0, 1439 -(Math.max(getScrollRange(), scrollX) + width)); 1440 mEdgeGlowRight.setSize(height, width); 1441 if (mEdgeGlowRight.draw(canvas)) { 1442 invalidate(); 1443 } 1444 canvas.restoreToCount(restoreCount); 1445 } 1446 } 1447 } 1448 1449 private int clamp(int n, int my, int child) { 1450 if (my >= child || n < 0) { 1451 return 0; 1452 } 1453 if ((my + n) > child) { 1454 return child - my; 1455 } 1456 return n; 1457 } 1458} 1459