HorizontalScrollView.java revision 33bbfd2232ea9eaae9a9d87a05a95a430f09bd83
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.widget; 18 19import com.android.internal.R; 20 21import android.content.Context; 22import android.content.res.Resources; 23import android.content.res.TypedArray; 24import android.graphics.Canvas; 25import android.graphics.Rect; 26import android.graphics.drawable.Drawable; 27import android.util.AttributeSet; 28import android.view.FocusFinder; 29import android.view.InputDevice; 30import android.view.KeyEvent; 31import android.view.MotionEvent; 32import android.view.VelocityTracker; 33import android.view.View; 34import android.view.ViewConfiguration; 35import android.view.ViewDebug; 36import android.view.ViewGroup; 37import android.view.ViewParent; 38import android.view.animation.AnimationUtils; 39 40import java.util.List; 41 42/** 43 * Layout container for a view hierarchy that can be scrolled by the user, 44 * allowing it to be larger than the physical display. A HorizontalScrollView 45 * is a {@link FrameLayout}, meaning you should place one child in it 46 * containing the entire contents to scroll; this child may itself be a layout 47 * manager with a complex hierarchy of objects. A child that is often used 48 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 49 * array of top-level items that the user can scroll through. 50 * 51 * <p>You should never use a HorizontalScrollView with a {@link ListView}, since 52 * ListView takes care of its own scrolling. Most importantly, doing this 53 * defeats all of the important optimizations in ListView for dealing with 54 * large lists, since it effectively forces the ListView to display its entire 55 * list of items to fill up the infinite container supplied by HorizontalScrollView. 56 * 57 * <p>The {@link TextView} class also 58 * takes care of its own scrolling, so does not require a ScrollView, but 59 * using the two together is possible to achieve the effect of a text view 60 * within a larger container. 61 * 62 * <p>HorizontalScrollView only supports horizontal scrolling. 63 * 64 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 65 */ 66public class HorizontalScrollView extends FrameLayout { 67 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 68 69 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 70 71 72 private long mLastScroll; 73 74 private final Rect mTempRect = new Rect(); 75 private OverScroller mScroller; 76 private EdgeGlow mEdgeGlowLeft; 77 private EdgeGlow mEdgeGlowRight; 78 79 /** 80 * Position of the last motion event. 81 */ 82 private float mLastMotionX; 83 84 /** 85 * True when the layout has changed but the traversal has not come through yet. 86 * Ideally the view hierarchy would keep track of this for us. 87 */ 88 private boolean mIsLayoutDirty = true; 89 90 /** 91 * The child to give focus to in the event that a child has requested focus while the 92 * layout is dirty. This prevents the scroll from being wrong if the child has not been 93 * laid out before requesting focus. 94 */ 95 private View mChildToScrollTo = null; 96 97 /** 98 * True if the user is currently dragging this ScrollView around. This is 99 * not the same as 'is being flinged', which can be checked by 100 * mScroller.isFinished() (flinging begins when the user lifts his finger). 101 */ 102 private boolean mIsBeingDragged = false; 103 104 /** 105 * Determines speed during touch scrolling 106 */ 107 private VelocityTracker mVelocityTracker; 108 109 /** 110 * When set to true, the scroll view measure its child to make it fill the currently 111 * visible area. 112 */ 113 @ViewDebug.ExportedProperty(category = "layout") 114 private boolean mFillViewport; 115 116 /** 117 * Whether arrow scrolling is animated. 118 */ 119 private boolean mSmoothScrollingEnabled = true; 120 121 private int mTouchSlop; 122 private int mMinimumVelocity; 123 private int mMaximumVelocity; 124 125 private int mOverscrollDistance; 126 private int mOverflingDistance; 127 128 /** 129 * ID of the active pointer. This is used to retain consistency during 130 * drags/flings if multiple pointers are used. 131 */ 132 private int mActivePointerId = INVALID_POINTER; 133 134 /** 135 * Sentinel value for no current active pointer. 136 * Used by {@link #mActivePointerId}. 137 */ 138 private static final int INVALID_POINTER = -1; 139 140 public HorizontalScrollView(Context context) { 141 this(context, null); 142 } 143 144 public HorizontalScrollView(Context context, AttributeSet attrs) { 145 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 146 } 147 148 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 149 super(context, attrs, defStyle); 150 initScrollView(); 151 152 TypedArray a = context.obtainStyledAttributes(attrs, 153 android.R.styleable.HorizontalScrollView, defStyle, 0); 154 155 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 156 157 a.recycle(); 158 } 159 160 @Override 161 protected float getLeftFadingEdgeStrength() { 162 if (getChildCount() == 0) { 163 return 0.0f; 164 } 165 166 final int length = getHorizontalFadingEdgeLength(); 167 if (mScrollX < length) { 168 return mScrollX / (float) length; 169 } 170 171 return 1.0f; 172 } 173 174 @Override 175 protected float getRightFadingEdgeStrength() { 176 if (getChildCount() == 0) { 177 return 0.0f; 178 } 179 180 final int length = getHorizontalFadingEdgeLength(); 181 final int rightEdge = getWidth() - mPaddingRight; 182 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 183 if (span < length) { 184 return span / (float) length; 185 } 186 187 return 1.0f; 188 } 189 190 /** 191 * @return The maximum amount this scroll view will scroll in response to 192 * an arrow event. 193 */ 194 public int getMaxScrollAmount() { 195 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 196 } 197 198 199 private void initScrollView() { 200 mScroller = new OverScroller(getContext()); 201 setFocusable(true); 202 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 203 setWillNotDraw(false); 204 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 205 mTouchSlop = configuration.getScaledTouchSlop(); 206 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 207 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 208 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 209 mOverflingDistance = configuration.getScaledOverflingDistance(); 210 } 211 212 @Override 213 public void addView(View child) { 214 if (getChildCount() > 0) { 215 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 216 } 217 218 super.addView(child); 219 } 220 221 @Override 222 public void addView(View child, int index) { 223 if (getChildCount() > 0) { 224 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 225 } 226 227 super.addView(child, index); 228 } 229 230 @Override 231 public void addView(View child, ViewGroup.LayoutParams params) { 232 if (getChildCount() > 0) { 233 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 234 } 235 236 super.addView(child, params); 237 } 238 239 @Override 240 public void addView(View child, int index, ViewGroup.LayoutParams params) { 241 if (getChildCount() > 0) { 242 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 243 } 244 245 super.addView(child, index, params); 246 } 247 248 /** 249 * @return Returns true this HorizontalScrollView can be scrolled 250 */ 251 private boolean canScroll() { 252 View child = getChildAt(0); 253 if (child != null) { 254 int childWidth = child.getWidth(); 255 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 256 } 257 return false; 258 } 259 260 /** 261 * Indicates whether this HorizontalScrollView's content is stretched to 262 * fill the viewport. 263 * 264 * @return True if the content fills the viewport, false otherwise. 265 * 266 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 267 */ 268 public boolean isFillViewport() { 269 return mFillViewport; 270 } 271 272 /** 273 * Indicates this HorizontalScrollView whether it should stretch its content width 274 * to fill the viewport or not. 275 * 276 * @param fillViewport True to stretch the content's width to the viewport's 277 * boundaries, false otherwise. 278 * 279 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 280 */ 281 public void setFillViewport(boolean fillViewport) { 282 if (fillViewport != mFillViewport) { 283 mFillViewport = fillViewport; 284 requestLayout(); 285 } 286 } 287 288 /** 289 * @return Whether arrow scrolling will animate its transition. 290 */ 291 public boolean isSmoothScrollingEnabled() { 292 return mSmoothScrollingEnabled; 293 } 294 295 /** 296 * Set whether arrow scrolling will animate its transition. 297 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 298 */ 299 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 300 mSmoothScrollingEnabled = smoothScrollingEnabled; 301 } 302 303 @Override 304 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 305 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 306 307 if (!mFillViewport) { 308 return; 309 } 310 311 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 312 if (widthMode == MeasureSpec.UNSPECIFIED) { 313 return; 314 } 315 316 if (getChildCount() > 0) { 317 final View child = getChildAt(0); 318 int width = getMeasuredWidth(); 319 if (child.getMeasuredWidth() < width) { 320 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 321 322 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 323 + mPaddingBottom, lp.height); 324 width -= mPaddingLeft; 325 width -= mPaddingRight; 326 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 327 328 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 329 } 330 } 331 } 332 333 @Override 334 public boolean dispatchKeyEvent(KeyEvent event) { 335 // Let the focused view and/or our descendants get the key first 336 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 337 } 338 339 /** 340 * You can call this function yourself to have the scroll view perform 341 * scrolling from a key event, just as if the event had been dispatched to 342 * it by the view hierarchy. 343 * 344 * @param event The key event to execute. 345 * @return Return true if the event was handled, else false. 346 */ 347 public boolean executeKeyEvent(KeyEvent event) { 348 mTempRect.setEmpty(); 349 350 if (!canScroll()) { 351 if (isFocused()) { 352 View currentFocused = findFocus(); 353 if (currentFocused == this) currentFocused = null; 354 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 355 currentFocused, View.FOCUS_RIGHT); 356 return nextFocused != null && nextFocused != this && 357 nextFocused.requestFocus(View.FOCUS_RIGHT); 358 } 359 return false; 360 } 361 362 boolean handled = false; 363 if (event.getAction() == KeyEvent.ACTION_DOWN) { 364 switch (event.getKeyCode()) { 365 case KeyEvent.KEYCODE_DPAD_LEFT: 366 if (!event.isAltPressed()) { 367 handled = arrowScroll(View.FOCUS_LEFT); 368 } else { 369 handled = fullScroll(View.FOCUS_LEFT); 370 } 371 break; 372 case KeyEvent.KEYCODE_DPAD_RIGHT: 373 if (!event.isAltPressed()) { 374 handled = arrowScroll(View.FOCUS_RIGHT); 375 } else { 376 handled = fullScroll(View.FOCUS_RIGHT); 377 } 378 break; 379 case KeyEvent.KEYCODE_SPACE: 380 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 381 break; 382 } 383 } 384 385 return handled; 386 } 387 388 private boolean inChild(int x, int y) { 389 if (getChildCount() > 0) { 390 final int scrollX = mScrollX; 391 final View child = getChildAt(0); 392 return !(y < child.getTop() 393 || y >= child.getBottom() 394 || x < child.getLeft() - scrollX 395 || x >= child.getRight() - scrollX); 396 } 397 return false; 398 } 399 400 @Override 401 public boolean onInterceptTouchEvent(MotionEvent ev) { 402 /* 403 * This method JUST determines whether we want to intercept the motion. 404 * If we return true, onMotionEvent will be called and we do the actual 405 * scrolling there. 406 */ 407 408 /* 409 * Shortcut the most recurring case: the user is in the dragging 410 * state and he is moving his finger. We want to intercept this 411 * motion. 412 */ 413 final int action = ev.getAction(); 414 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 415 return true; 416 } 417 418 switch (action & MotionEvent.ACTION_MASK) { 419 case MotionEvent.ACTION_MOVE: { 420 /* 421 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 422 * whether the user has moved far enough from his original down touch. 423 */ 424 425 /* 426 * Locally do absolute value. mLastMotionX is set to the x value 427 * of the down event. 428 */ 429 final int activePointerId = mActivePointerId; 430 if (activePointerId == INVALID_POINTER) { 431 // If we don't have a valid id, the touch down wasn't on content. 432 break; 433 } 434 435 final int pointerIndex = ev.findPointerIndex(activePointerId); 436 final float x = ev.getX(pointerIndex); 437 final int xDiff = (int) Math.abs(x - mLastMotionX); 438 if (xDiff > mTouchSlop) { 439 mIsBeingDragged = true; 440 mLastMotionX = x; 441 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 442 } 443 break; 444 } 445 446 case MotionEvent.ACTION_DOWN: { 447 final float x = ev.getX(); 448 if (!inChild((int) x, (int) ev.getY())) { 449 mIsBeingDragged = false; 450 break; 451 } 452 453 /* 454 * Remember location of down touch. 455 * ACTION_DOWN always refers to pointer index 0. 456 */ 457 mLastMotionX = x; 458 mActivePointerId = ev.getPointerId(0); 459 460 /* 461 * If being flinged and user touches the screen, initiate drag; 462 * otherwise don't. mScroller.isFinished should be false when 463 * being flinged. 464 */ 465 mIsBeingDragged = !mScroller.isFinished(); 466 break; 467 } 468 469 case MotionEvent.ACTION_CANCEL: 470 case MotionEvent.ACTION_UP: 471 /* Release the drag */ 472 mIsBeingDragged = false; 473 mActivePointerId = INVALID_POINTER; 474 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 475 invalidate(); 476 } 477 break; 478 case MotionEvent.ACTION_POINTER_UP: 479 onSecondaryPointerUp(ev); 480 break; 481 } 482 483 /* 484 * The only time we want to intercept motion events is if we are in the 485 * drag mode. 486 */ 487 return mIsBeingDragged; 488 } 489 490 @Override 491 public boolean onTouchEvent(MotionEvent ev) { 492 493 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 494 // Don't handle edge touches immediately -- they may actually belong to one of our 495 // descendants. 496 return false; 497 } 498 499 if (mVelocityTracker == null) { 500 mVelocityTracker = VelocityTracker.obtain(); 501 } 502 mVelocityTracker.addMovement(ev); 503 504 final int action = ev.getAction(); 505 506 switch (action & MotionEvent.ACTION_MASK) { 507 case MotionEvent.ACTION_DOWN: { 508 mIsBeingDragged = getChildCount() != 0; 509 if (!mIsBeingDragged) { 510 return false; 511 } 512 513 /* 514 * If being flinged and user touches, stop the fling. isFinished 515 * will be false if being flinged. 516 */ 517 if (!mScroller.isFinished()) { 518 mScroller.abortAnimation(); 519 } 520 521 // Remember where the motion event started 522 mLastMotionX = ev.getX(); 523 mActivePointerId = ev.getPointerId(0); 524 break; 525 } 526 case MotionEvent.ACTION_MOVE: 527 if (mIsBeingDragged) { 528 // Scroll to follow the motion event 529 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 530 final float x = ev.getX(activePointerIndex); 531 final int deltaX = (int) (mLastMotionX - x); 532 mLastMotionX = x; 533 534 final int oldX = mScrollX; 535 final int oldY = mScrollY; 536 final int range = getScrollRange(); 537 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 538 mOverscrollDistance, 0, true)) { 539 // Break our velocity if we hit a scroll barrier. 540 mVelocityTracker.clear(); 541 } 542 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 543 544 final int overscrollMode = getOverScrollMode(); 545 if (overscrollMode == OVER_SCROLL_ALWAYS || 546 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 547 final int pulledToX = oldX + deltaX; 548 if (pulledToX < 0) { 549 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 550 if (!mEdgeGlowRight.isFinished()) { 551 mEdgeGlowRight.onRelease(); 552 } 553 } else if (pulledToX > range) { 554 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 555 if (!mEdgeGlowLeft.isFinished()) { 556 mEdgeGlowLeft.onRelease(); 557 } 558 } 559 if (mEdgeGlowLeft != null 560 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 561 invalidate(); 562 } 563 } 564 } 565 break; 566 case MotionEvent.ACTION_UP: 567 if (mIsBeingDragged) { 568 final VelocityTracker velocityTracker = mVelocityTracker; 569 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 570 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 571 572 if (getChildCount() > 0) { 573 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 574 fling(-initialVelocity); 575 } else { 576 final int right = getScrollRange(); 577 if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { 578 invalidate(); 579 } 580 } 581 } 582 583 mActivePointerId = INVALID_POINTER; 584 mIsBeingDragged = false; 585 586 if (mVelocityTracker != null) { 587 mVelocityTracker.recycle(); 588 mVelocityTracker = null; 589 } 590 if (mEdgeGlowLeft != null) { 591 mEdgeGlowLeft.onRelease(); 592 mEdgeGlowRight.onRelease(); 593 } 594 } 595 break; 596 case MotionEvent.ACTION_CANCEL: 597 if (mIsBeingDragged && getChildCount() > 0) { 598 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 599 invalidate(); 600 } 601 mActivePointerId = INVALID_POINTER; 602 mIsBeingDragged = false; 603 if (mVelocityTracker != null) { 604 mVelocityTracker.recycle(); 605 mVelocityTracker = null; 606 } 607 if (mEdgeGlowLeft != null) { 608 mEdgeGlowLeft.onRelease(); 609 mEdgeGlowRight.onRelease(); 610 } 611 } 612 break; 613 case MotionEvent.ACTION_POINTER_UP: 614 onSecondaryPointerUp(ev); 615 break; 616 } 617 return true; 618 } 619 620 private void onSecondaryPointerUp(MotionEvent ev) { 621 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 622 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 623 final int pointerId = ev.getPointerId(pointerIndex); 624 if (pointerId == mActivePointerId) { 625 // This was our active pointer going up. Choose a new 626 // active pointer and adjust accordingly. 627 // TODO: Make this decision more intelligent. 628 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 629 mLastMotionX = ev.getX(newPointerIndex); 630 mActivePointerId = ev.getPointerId(newPointerIndex); 631 if (mVelocityTracker != null) { 632 mVelocityTracker.clear(); 633 } 634 } 635 } 636 637 @Override 638 public boolean onGenericMotionEvent(MotionEvent event) { 639 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 640 switch (event.getAction()) { 641 case MotionEvent.ACTION_SCROLL: { 642 if (!mIsBeingDragged) { 643 final float hscroll; 644 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 645 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 646 } else { 647 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 648 } 649 if (hscroll != 0) { 650 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 651 final int range = getScrollRange(); 652 int oldScrollX = mScrollX; 653 int newScrollX = oldScrollX + delta; 654 if (newScrollX < 0) { 655 newScrollX = 0; 656 } else if (newScrollX > range) { 657 newScrollX = range; 658 } 659 if (newScrollX != oldScrollX) { 660 super.scrollTo(newScrollX, mScrollY); 661 return true; 662 } 663 } 664 } 665 } 666 } 667 } 668 return super.onGenericMotionEvent(event); 669 } 670 671 @Override 672 protected void onOverScrolled(int scrollX, int scrollY, 673 boolean clampedX, boolean clampedY) { 674 // Treat animating scrolls differently; see #computeScroll() for why. 675 if (!mScroller.isFinished()) { 676 mScrollX = scrollX; 677 mScrollY = scrollY; 678 invalidateParentIfNeeded(); 679 if (clampedX) { 680 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 681 } 682 } else { 683 super.scrollTo(scrollX, scrollY); 684 } 685 awakenScrollBars(); 686 } 687 688 private int getScrollRange() { 689 int scrollRange = 0; 690 if (getChildCount() > 0) { 691 View child = getChildAt(0); 692 scrollRange = Math.max(0, 693 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 694 } 695 return scrollRange; 696 } 697 698 /** 699 * <p> 700 * Finds the next focusable component that fits in this View's bounds 701 * (excluding fading edges) pretending that this View's left is located at 702 * the parameter left. 703 * </p> 704 * 705 * @param leftFocus look for a candidate is the one at the left of the bounds 706 * if leftFocus is true, or at the right of the bounds if leftFocus 707 * is false 708 * @param left the left offset of the bounds in which a focusable must be 709 * found (the fading edge is assumed to start at this position) 710 * @param preferredFocusable the View that has highest priority and will be 711 * returned if it is within my bounds (null is valid) 712 * @return the next focusable component in the bounds or null if none can be found 713 */ 714 private View findFocusableViewInMyBounds(final boolean leftFocus, 715 final int left, View preferredFocusable) { 716 /* 717 * The fading edge's transparent side should be considered for focus 718 * since it's mostly visible, so we divide the actual fading edge length 719 * by 2. 720 */ 721 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 722 final int leftWithoutFadingEdge = left + fadingEdgeLength; 723 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 724 725 if ((preferredFocusable != null) 726 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 727 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 728 return preferredFocusable; 729 } 730 731 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 732 rightWithoutFadingEdge); 733 } 734 735 /** 736 * <p> 737 * Finds the next focusable component that fits in the specified bounds. 738 * </p> 739 * 740 * @param leftFocus look for a candidate is the one at the left of the bounds 741 * if leftFocus is true, or at the right of the bounds if 742 * leftFocus is false 743 * @param left the left offset of the bounds in which a focusable must be 744 * found 745 * @param right the right offset of the bounds in which a focusable must 746 * be found 747 * @return the next focusable component in the bounds or null if none can 748 * be found 749 */ 750 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 751 752 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 753 View focusCandidate = null; 754 755 /* 756 * A fully contained focusable is one where its left is below the bound's 757 * left, and its right is above the bound's right. A partially 758 * contained focusable is one where some part of it is within the 759 * bounds, but it also has some part that is not within bounds. A fully contained 760 * focusable is preferred to a partially contained focusable. 761 */ 762 boolean foundFullyContainedFocusable = false; 763 764 int count = focusables.size(); 765 for (int i = 0; i < count; i++) { 766 View view = focusables.get(i); 767 int viewLeft = view.getLeft(); 768 int viewRight = view.getRight(); 769 770 if (left < viewRight && viewLeft < right) { 771 /* 772 * the focusable is in the target area, it is a candidate for 773 * focusing 774 */ 775 776 final boolean viewIsFullyContained = (left < viewLeft) && 777 (viewRight < right); 778 779 if (focusCandidate == null) { 780 /* No candidate, take this one */ 781 focusCandidate = view; 782 foundFullyContainedFocusable = viewIsFullyContained; 783 } else { 784 final boolean viewIsCloserToBoundary = 785 (leftFocus && viewLeft < focusCandidate.getLeft()) || 786 (!leftFocus && viewRight > focusCandidate.getRight()); 787 788 if (foundFullyContainedFocusable) { 789 if (viewIsFullyContained && viewIsCloserToBoundary) { 790 /* 791 * We're dealing with only fully contained views, so 792 * it has to be closer to the boundary to beat our 793 * candidate 794 */ 795 focusCandidate = view; 796 } 797 } else { 798 if (viewIsFullyContained) { 799 /* Any fully contained view beats a partially contained view */ 800 focusCandidate = view; 801 foundFullyContainedFocusable = true; 802 } else if (viewIsCloserToBoundary) { 803 /* 804 * Partially contained view beats another partially 805 * contained view if it's closer 806 */ 807 focusCandidate = view; 808 } 809 } 810 } 811 } 812 } 813 814 return focusCandidate; 815 } 816 817 /** 818 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 819 * method will scroll the view by one page left or right and give the focus 820 * to the leftmost/rightmost component in the new visible area. If no 821 * component is a good candidate for focus, this scrollview reclaims the 822 * focus.</p> 823 * 824 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 825 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 826 * to go one page right 827 * @return true if the key event is consumed by this method, false otherwise 828 */ 829 public boolean pageScroll(int direction) { 830 boolean right = direction == View.FOCUS_RIGHT; 831 int width = getWidth(); 832 833 if (right) { 834 mTempRect.left = getScrollX() + width; 835 int count = getChildCount(); 836 if (count > 0) { 837 View view = getChildAt(0); 838 if (mTempRect.left + width > view.getRight()) { 839 mTempRect.left = view.getRight() - width; 840 } 841 } 842 } else { 843 mTempRect.left = getScrollX() - width; 844 if (mTempRect.left < 0) { 845 mTempRect.left = 0; 846 } 847 } 848 mTempRect.right = mTempRect.left + width; 849 850 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 851 } 852 853 /** 854 * <p>Handles scrolling in response to a "home/end" shortcut press. This 855 * method will scroll the view to the left or right and give the focus 856 * to the leftmost/rightmost component in the new visible area. If no 857 * component is a good candidate for focus, this scrollview reclaims the 858 * focus.</p> 859 * 860 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 861 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 862 * to go the right 863 * @return true if the key event is consumed by this method, false otherwise 864 */ 865 public boolean fullScroll(int direction) { 866 boolean right = direction == View.FOCUS_RIGHT; 867 int width = getWidth(); 868 869 mTempRect.left = 0; 870 mTempRect.right = width; 871 872 if (right) { 873 int count = getChildCount(); 874 if (count > 0) { 875 View view = getChildAt(0); 876 mTempRect.right = view.getRight(); 877 mTempRect.left = mTempRect.right - width; 878 } 879 } 880 881 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 882 } 883 884 /** 885 * <p>Scrolls the view to make the area defined by <code>left</code> and 886 * <code>right</code> visible. This method attempts to give the focus 887 * to a component visible in this area. If no component can be focused in 888 * the new visible area, the focus is reclaimed by this scrollview.</p> 889 * 890 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 891 * to go left {@link android.view.View#FOCUS_RIGHT} to right 892 * @param left the left offset of the new area to be made visible 893 * @param right the right offset of the new area to be made visible 894 * @return true if the key event is consumed by this method, false otherwise 895 */ 896 private boolean scrollAndFocus(int direction, int left, int right) { 897 boolean handled = true; 898 899 int width = getWidth(); 900 int containerLeft = getScrollX(); 901 int containerRight = containerLeft + width; 902 boolean goLeft = direction == View.FOCUS_LEFT; 903 904 View newFocused = findFocusableViewInBounds(goLeft, left, right); 905 if (newFocused == null) { 906 newFocused = this; 907 } 908 909 if (left >= containerLeft && right <= containerRight) { 910 handled = false; 911 } else { 912 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 913 doScrollX(delta); 914 } 915 916 if (newFocused != findFocus()) newFocused.requestFocus(direction); 917 918 return handled; 919 } 920 921 /** 922 * Handle scrolling in response to a left or right arrow click. 923 * 924 * @param direction The direction corresponding to the arrow key that was 925 * pressed 926 * @return True if we consumed the event, false otherwise 927 */ 928 public boolean arrowScroll(int direction) { 929 930 View currentFocused = findFocus(); 931 if (currentFocused == this) currentFocused = null; 932 933 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 934 935 final int maxJump = getMaxScrollAmount(); 936 937 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 938 nextFocused.getDrawingRect(mTempRect); 939 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 940 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 941 doScrollX(scrollDelta); 942 nextFocused.requestFocus(direction); 943 } else { 944 // no new focus 945 int scrollDelta = maxJump; 946 947 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 948 scrollDelta = getScrollX(); 949 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 950 951 int daRight = getChildAt(0).getRight(); 952 953 int screenRight = getScrollX() + getWidth(); 954 955 if (daRight - screenRight < maxJump) { 956 scrollDelta = daRight - screenRight; 957 } 958 } 959 if (scrollDelta == 0) { 960 return false; 961 } 962 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 963 } 964 965 if (currentFocused != null && currentFocused.isFocused() 966 && isOffScreen(currentFocused)) { 967 // previously focused item still has focus and is off screen, give 968 // it up (take it back to ourselves) 969 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 970 // sure to 971 // get it) 972 final int descendantFocusability = getDescendantFocusability(); // save 973 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 974 requestFocus(); 975 setDescendantFocusability(descendantFocusability); // restore 976 } 977 return true; 978 } 979 980 /** 981 * @return whether the descendant of this scroll view is scrolled off 982 * screen. 983 */ 984 private boolean isOffScreen(View descendant) { 985 return !isWithinDeltaOfScreen(descendant, 0); 986 } 987 988 /** 989 * @return whether the descendant of this scroll view is within delta 990 * pixels of being on the screen. 991 */ 992 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 993 descendant.getDrawingRect(mTempRect); 994 offsetDescendantRectToMyCoords(descendant, mTempRect); 995 996 return (mTempRect.right + delta) >= getScrollX() 997 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 998 } 999 1000 /** 1001 * Smooth scroll by a X delta 1002 * 1003 * @param delta the number of pixels to scroll by on the X axis 1004 */ 1005 private void doScrollX(int delta) { 1006 if (delta != 0) { 1007 if (mSmoothScrollingEnabled) { 1008 smoothScrollBy(delta, 0); 1009 } else { 1010 scrollBy(delta, 0); 1011 } 1012 } 1013 } 1014 1015 /** 1016 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1017 * 1018 * @param dx the number of pixels to scroll by on the X axis 1019 * @param dy the number of pixels to scroll by on the Y axis 1020 */ 1021 public final void smoothScrollBy(int dx, int dy) { 1022 if (getChildCount() == 0) { 1023 // Nothing to do. 1024 return; 1025 } 1026 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1027 if (duration > ANIMATED_SCROLL_GAP) { 1028 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1029 final int right = getChildAt(0).getWidth(); 1030 final int maxX = Math.max(0, right - width); 1031 final int scrollX = mScrollX; 1032 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1033 1034 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1035 invalidate(); 1036 } else { 1037 if (!mScroller.isFinished()) { 1038 mScroller.abortAnimation(); 1039 } 1040 scrollBy(dx, dy); 1041 } 1042 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1043 } 1044 1045 /** 1046 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1047 * 1048 * @param x the position where to scroll on the X axis 1049 * @param y the position where to scroll on the Y axis 1050 */ 1051 public final void smoothScrollTo(int x, int y) { 1052 smoothScrollBy(x - mScrollX, y - mScrollY); 1053 } 1054 1055 /** 1056 * <p>The scroll range of a scroll view is the overall width of all of its 1057 * children.</p> 1058 */ 1059 @Override 1060 protected int computeHorizontalScrollRange() { 1061 final int count = getChildCount(); 1062 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1063 if (count == 0) { 1064 return contentWidth; 1065 } 1066 1067 int scrollRange = getChildAt(0).getRight(); 1068 final int scrollX = mScrollX; 1069 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1070 if (scrollX < 0) { 1071 scrollRange -= scrollX; 1072 } else if (scrollX > overscrollRight) { 1073 scrollRange += scrollX - overscrollRight; 1074 } 1075 1076 return scrollRange; 1077 } 1078 1079 @Override 1080 protected int computeHorizontalScrollOffset() { 1081 return Math.max(0, super.computeHorizontalScrollOffset()); 1082 } 1083 1084 @Override 1085 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1086 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1087 1088 int childWidthMeasureSpec; 1089 int childHeightMeasureSpec; 1090 1091 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1092 + mPaddingBottom, lp.height); 1093 1094 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1095 1096 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1097 } 1098 1099 @Override 1100 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1101 int parentHeightMeasureSpec, int heightUsed) { 1102 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1103 1104 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1105 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1106 + heightUsed, lp.height); 1107 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1108 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1109 1110 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1111 } 1112 1113 @Override 1114 public void computeScroll() { 1115 if (mScroller.computeScrollOffset()) { 1116 // This is called at drawing time by ViewGroup. We don't want to 1117 // re-show the scrollbars at this point, which scrollTo will do, 1118 // so we replicate most of scrollTo here. 1119 // 1120 // It's a little odd to call onScrollChanged from inside the drawing. 1121 // 1122 // It is, except when you remember that computeScroll() is used to 1123 // animate scrolling. So unless we want to defer the onScrollChanged() 1124 // until the end of the animated scrolling, we don't really have a 1125 // choice here. 1126 // 1127 // I agree. The alternative, which I think would be worse, is to post 1128 // something and tell the subclasses later. This is bad because there 1129 // will be a window where mScrollX/Y is different from what the app 1130 // thinks it is. 1131 // 1132 int oldX = mScrollX; 1133 int oldY = mScrollY; 1134 int x = mScroller.getCurrX(); 1135 int y = mScroller.getCurrY(); 1136 1137 if (oldX != x || oldY != y) { 1138 overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, 1139 mOverflingDistance, 0, false); 1140 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1141 1142 final int range = getScrollRange(); 1143 final int overscrollMode = getOverScrollMode(); 1144 if (overscrollMode == OVER_SCROLL_ALWAYS || 1145 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1146 if (x < 0 && oldX >= 0) { 1147 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1148 } else if (x > range && oldX <= range) { 1149 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1150 } 1151 } 1152 } 1153 awakenScrollBars(); 1154 1155 // Keep on drawing until the animation has finished. 1156 postInvalidate(); 1157 } 1158 } 1159 1160 /** 1161 * Scrolls the view to the given child. 1162 * 1163 * @param child the View to scroll to 1164 */ 1165 private void scrollToChild(View child) { 1166 child.getDrawingRect(mTempRect); 1167 1168 /* Offset from child's local coordinates to ScrollView coordinates */ 1169 offsetDescendantRectToMyCoords(child, mTempRect); 1170 1171 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1172 1173 if (scrollDelta != 0) { 1174 scrollBy(scrollDelta, 0); 1175 } 1176 } 1177 1178 /** 1179 * If rect is off screen, scroll just enough to get it (or at least the 1180 * first screen size chunk of it) on screen. 1181 * 1182 * @param rect The rectangle. 1183 * @param immediate True to scroll immediately without animation 1184 * @return true if scrolling was performed 1185 */ 1186 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1187 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1188 final boolean scroll = delta != 0; 1189 if (scroll) { 1190 if (immediate) { 1191 scrollBy(delta, 0); 1192 } else { 1193 smoothScrollBy(delta, 0); 1194 } 1195 } 1196 return scroll; 1197 } 1198 1199 /** 1200 * Compute the amount to scroll in the X direction in order to get 1201 * a rectangle completely on the screen (or, if taller than the screen, 1202 * at least the first screen size chunk of it). 1203 * 1204 * @param rect The rect. 1205 * @return The scroll delta. 1206 */ 1207 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1208 if (getChildCount() == 0) return 0; 1209 1210 int width = getWidth(); 1211 int screenLeft = getScrollX(); 1212 int screenRight = screenLeft + width; 1213 1214 int fadingEdge = getHorizontalFadingEdgeLength(); 1215 1216 // leave room for left fading edge as long as rect isn't at very left 1217 if (rect.left > 0) { 1218 screenLeft += fadingEdge; 1219 } 1220 1221 // leave room for right fading edge as long as rect isn't at very right 1222 if (rect.right < getChildAt(0).getWidth()) { 1223 screenRight -= fadingEdge; 1224 } 1225 1226 int scrollXDelta = 0; 1227 1228 if (rect.right > screenRight && rect.left > screenLeft) { 1229 // need to move right to get it in view: move right just enough so 1230 // that the entire rectangle is in view (or at least the first 1231 // screen size chunk). 1232 1233 if (rect.width() > width) { 1234 // just enough to get screen size chunk on 1235 scrollXDelta += (rect.left - screenLeft); 1236 } else { 1237 // get entire rect at right of screen 1238 scrollXDelta += (rect.right - screenRight); 1239 } 1240 1241 // make sure we aren't scrolling beyond the end of our content 1242 int right = getChildAt(0).getRight(); 1243 int distanceToRight = right - screenRight; 1244 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1245 1246 } else if (rect.left < screenLeft && rect.right < screenRight) { 1247 // need to move right to get it in view: move right just enough so that 1248 // entire rectangle is in view (or at least the first screen 1249 // size chunk of it). 1250 1251 if (rect.width() > width) { 1252 // screen size chunk 1253 scrollXDelta -= (screenRight - rect.right); 1254 } else { 1255 // entire rect at left 1256 scrollXDelta -= (screenLeft - rect.left); 1257 } 1258 1259 // make sure we aren't scrolling any further than the left our content 1260 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1261 } 1262 return scrollXDelta; 1263 } 1264 1265 @Override 1266 public void requestChildFocus(View child, View focused) { 1267 if (!mIsLayoutDirty) { 1268 scrollToChild(focused); 1269 } else { 1270 // The child may not be laid out yet, we can't compute the scroll yet 1271 mChildToScrollTo = focused; 1272 } 1273 super.requestChildFocus(child, focused); 1274 } 1275 1276 1277 /** 1278 * When looking for focus in children of a scroll view, need to be a little 1279 * more careful not to give focus to something that is scrolled off screen. 1280 * 1281 * This is more expensive than the default {@link android.view.ViewGroup} 1282 * implementation, otherwise this behavior might have been made the default. 1283 */ 1284 @Override 1285 protected boolean onRequestFocusInDescendants(int direction, 1286 Rect previouslyFocusedRect) { 1287 1288 // convert from forward / backward notation to up / down / left / right 1289 // (ugh). 1290 if (direction == View.FOCUS_FORWARD) { 1291 direction = View.FOCUS_RIGHT; 1292 } else if (direction == View.FOCUS_BACKWARD) { 1293 direction = View.FOCUS_LEFT; 1294 } 1295 1296 final View nextFocus = previouslyFocusedRect == null ? 1297 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1298 FocusFinder.getInstance().findNextFocusFromRect(this, 1299 previouslyFocusedRect, direction); 1300 1301 if (nextFocus == null) { 1302 return false; 1303 } 1304 1305 if (isOffScreen(nextFocus)) { 1306 return false; 1307 } 1308 1309 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1310 } 1311 1312 @Override 1313 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1314 boolean immediate) { 1315 // offset into coordinate space of this scroll view 1316 rectangle.offset(child.getLeft() - child.getScrollX(), 1317 child.getTop() - child.getScrollY()); 1318 1319 return scrollToChildRect(rectangle, immediate); 1320 } 1321 1322 @Override 1323 public void requestLayout() { 1324 mIsLayoutDirty = true; 1325 super.requestLayout(); 1326 } 1327 1328 @Override 1329 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1330 super.onLayout(changed, l, t, r, b); 1331 mIsLayoutDirty = false; 1332 // Give a child focus if it needs it 1333 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1334 scrollToChild(mChildToScrollTo); 1335 } 1336 mChildToScrollTo = null; 1337 1338 // Calling this with the present values causes it to re-clam them 1339 scrollTo(mScrollX, mScrollY); 1340 } 1341 1342 @Override 1343 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1344 super.onSizeChanged(w, h, oldw, oldh); 1345 1346 View currentFocused = findFocus(); 1347 if (null == currentFocused || this == currentFocused) 1348 return; 1349 1350 final int maxJump = mRight - mLeft; 1351 1352 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1353 currentFocused.getDrawingRect(mTempRect); 1354 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1355 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1356 doScrollX(scrollDelta); 1357 } 1358 } 1359 1360 /** 1361 * Return true if child is an descendant of parent, (or equal to the parent). 1362 */ 1363 private boolean isViewDescendantOf(View child, View parent) { 1364 if (child == parent) { 1365 return true; 1366 } 1367 1368 final ViewParent theParent = child.getParent(); 1369 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1370 } 1371 1372 /** 1373 * Fling the scroll view 1374 * 1375 * @param velocityX The initial velocity in the X direction. Positive 1376 * numbers mean that the finger/curor is moving down the screen, 1377 * which means we want to scroll towards the left. 1378 */ 1379 public void fling(int velocityX) { 1380 if (getChildCount() > 0) { 1381 int width = getWidth() - mPaddingRight - mPaddingLeft; 1382 int right = getChildAt(0).getWidth(); 1383 1384 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1385 Math.max(0, right - width), 0, 0, width/2, 0); 1386 1387 final boolean movingRight = velocityX > 0; 1388 1389 View currentFocused = findFocus(); 1390 View newFocused = findFocusableViewInMyBounds(movingRight, 1391 mScroller.getFinalX(), currentFocused); 1392 1393 if (newFocused == null) { 1394 newFocused = this; 1395 } 1396 1397 if (newFocused != currentFocused) { 1398 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1399 } 1400 1401 invalidate(); 1402 } 1403 } 1404 1405 /** 1406 * {@inheritDoc} 1407 * 1408 * <p>This version also clamps the scrolling to the bounds of our child. 1409 */ 1410 @Override 1411 public void scrollTo(int x, int y) { 1412 // we rely on the fact the View.scrollBy calls scrollTo. 1413 if (getChildCount() > 0) { 1414 View child = getChildAt(0); 1415 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1416 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1417 if (x != mScrollX || y != mScrollY) { 1418 super.scrollTo(x, y); 1419 } 1420 } 1421 } 1422 1423 @Override 1424 public void setOverScrollMode(int mode) { 1425 if (mode != OVER_SCROLL_NEVER) { 1426 if (mEdgeGlowLeft == null) { 1427 Context context = getContext(); 1428 final Resources res = context.getResources(); 1429 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1430 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1431 mEdgeGlowLeft = new EdgeGlow(context, edge, glow); 1432 mEdgeGlowRight = new EdgeGlow(context, edge, glow); 1433 } 1434 } else { 1435 mEdgeGlowLeft = null; 1436 mEdgeGlowRight = null; 1437 } 1438 super.setOverScrollMode(mode); 1439 } 1440 1441 @Override 1442 public void draw(Canvas canvas) { 1443 super.draw(canvas); 1444 if (mEdgeGlowLeft != null) { 1445 final int scrollX = mScrollX; 1446 if (!mEdgeGlowLeft.isFinished()) { 1447 final int restoreCount = canvas.save(); 1448 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1449 1450 canvas.rotate(270); 1451 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1452 mEdgeGlowLeft.setSize(height, getWidth()); 1453 if (mEdgeGlowLeft.draw(canvas)) { 1454 invalidate(); 1455 } 1456 canvas.restoreToCount(restoreCount); 1457 } 1458 if (!mEdgeGlowRight.isFinished()) { 1459 final int restoreCount = canvas.save(); 1460 final int width = getWidth(); 1461 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1462 1463 canvas.rotate(90); 1464 canvas.translate(-mPaddingTop, 1465 -(Math.max(getScrollRange(), scrollX) + width)); 1466 mEdgeGlowRight.setSize(height, width); 1467 if (mEdgeGlowRight.draw(canvas)) { 1468 invalidate(); 1469 } 1470 canvas.restoreToCount(restoreCount); 1471 } 1472 } 1473 } 1474 1475 private int clamp(int n, int my, int child) { 1476 if (my >= child || n < 0) { 1477 return 0; 1478 } 1479 if ((my + n) > child) { 1480 return child - my; 1481 } 1482 return n; 1483 } 1484} 1485