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 17 package android.widget; 18 19 import com.android.internal.R; 20 21 import android.util.AttributeSet; 22 import android.graphics.Canvas; 23 import android.graphics.Rect; 24 import android.graphics.drawable.Drawable; 25 import android.view.View; 26 import android.view.VelocityTracker; 27 import android.view.ViewConfiguration; 28 import android.view.ViewGroup; 29 import android.view.KeyEvent; 30 import android.view.FocusFinder; 31 import android.view.MotionEvent; 32 import android.view.ViewParent; 33 import android.view.animation.AnimationUtils; 34 import android.content.Context; 35 import android.content.res.Resources; 36 import android.content.res.TypedArray; 37 38 import java.util.List; 39 40 /** 41 * Layout container for a view hierarchy that can be scrolled by the user, 42 * allowing it to be larger than the physical display. A HorizontalScrollView 43 * is a {@link FrameLayout}, meaning you should place one child in it 44 * containing the entire contents to scroll; this child may itself be a layout 45 * manager with a complex hierarchy of objects. A child that is often used 46 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 47 * array of top-level items that the user can scroll through. 48 * 49 * <p>You should never use a HorizontalScrollView with a {@link ListView}, since 50 * ListView takes care of its own scrolling. Most importantly, doing this 51 * defeats all of the important optimizations in ListView for dealing with 52 * large lists, since it effectively forces the ListView to display its entire 53 * list of items to fill up the infinite container supplied by HorizontalScrollView. 54 * 55 * <p>The {@link TextView} class also 56 * takes care of its own scrolling, so does not require a ScrollView, but 57 * using the two together is possible to achieve the effect of a text view 58 * within a larger container. 59 * 60 * <p>HorizontalScrollView only supports horizontal scrolling. 61 */ 62 public class HorizontalScrollView extends FrameLayout { 63 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 64 65 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 66 67 68 private long mLastScroll; 69 70 private final Rect mTempRect = new Rect(); 71 private OverScroller mScroller; 72 private EdgeGlow mEdgeGlowLeft; 73 private EdgeGlow mEdgeGlowRight; 74 75 /** 76 * Flag to indicate that we are moving focus ourselves. This is so the 77 * code that watches for focus changes initiated outside this ScrollView 78 * knows that it does not have to do anything. 79 */ 80 private boolean mScrollViewMovedFocus; 81 82 /** 83 * Position of the last motion event. 84 */ 85 private float mLastMotionX; 86 87 /** 88 * True when the layout has changed but the traversal has not come through yet. 89 * Ideally the view hierarchy would keep track of this for us. 90 */ 91 private boolean mIsLayoutDirty = true; 92 93 /** 94 * The child to give focus to in the event that a child has requested focus while the 95 * layout is dirty. This prevents the scroll from being wrong if the child has not been 96 * laid out before requesting focus. 97 */ 98 private View mChildToScrollTo = null; 99 100 /** 101 * True if the user is currently dragging this ScrollView around. This is 102 * not the same as 'is being flinged', which can be checked by 103 * mScroller.isFinished() (flinging begins when the user lifts his finger). 104 */ 105 private boolean mIsBeingDragged = false; 106 107 /** 108 * Determines speed during touch scrolling 109 */ 110 private VelocityTracker mVelocityTracker; 111 112 /** 113 * When set to true, the scroll view measure its child to make it fill the currently 114 * visible area. 115 */ 116 private boolean mFillViewport; 117 118 /** 119 * Whether arrow scrolling is animated. 120 */ 121 private boolean mSmoothScrollingEnabled = true; 122 123 private int mTouchSlop; 124 private int mMinimumVelocity; 125 private int mMaximumVelocity; 126 127 private int mOverscrollDistance; 128 private int mOverflingDistance; 129 130 /** 131 * ID of the active pointer. This is used to retain consistency during 132 * drags/flings if multiple pointers are used. 133 */ 134 private int mActivePointerId = INVALID_POINTER; 135 136 /** 137 * Sentinel value for no current active pointer. 138 * Used by {@link #mActivePointerId}. 139 */ 140 private static final int INVALID_POINTER = -1; 141 HorizontalScrollView(Context context)142 public HorizontalScrollView(Context context) { 143 this(context, null); 144 } 145 HorizontalScrollView(Context context, AttributeSet attrs)146 public HorizontalScrollView(Context context, AttributeSet attrs) { 147 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 148 } 149 HorizontalScrollView(Context context, AttributeSet attrs, int defStyle)150 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 151 super(context, attrs, defStyle); 152 initScrollView(); 153 154 TypedArray a = context.obtainStyledAttributes(attrs, 155 android.R.styleable.HorizontalScrollView, defStyle, 0); 156 157 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 158 159 a.recycle(); 160 } 161 162 @Override getLeftFadingEdgeStrength()163 protected float getLeftFadingEdgeStrength() { 164 if (getChildCount() == 0) { 165 return 0.0f; 166 } 167 168 final int length = getHorizontalFadingEdgeLength(); 169 if (mScrollX < length) { 170 return mScrollX / (float) length; 171 } 172 173 return 1.0f; 174 } 175 176 @Override getRightFadingEdgeStrength()177 protected float getRightFadingEdgeStrength() { 178 if (getChildCount() == 0) { 179 return 0.0f; 180 } 181 182 final int length = getHorizontalFadingEdgeLength(); 183 final int rightEdge = getWidth() - mPaddingRight; 184 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 185 if (span < length) { 186 return span / (float) length; 187 } 188 189 return 1.0f; 190 } 191 192 /** 193 * @return The maximum amount this scroll view will scroll in response to 194 * an arrow event. 195 */ getMaxScrollAmount()196 public int getMaxScrollAmount() { 197 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 198 } 199 200 initScrollView()201 private void initScrollView() { 202 mScroller = new OverScroller(getContext()); 203 setFocusable(true); 204 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 205 setWillNotDraw(false); 206 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 207 mTouchSlop = configuration.getScaledTouchSlop(); 208 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 209 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 210 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 211 mOverflingDistance = configuration.getScaledOverflingDistance(); 212 } 213 214 @Override addView(View child)215 public void addView(View child) { 216 if (getChildCount() > 0) { 217 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 218 } 219 220 super.addView(child); 221 } 222 223 @Override addView(View child, int index)224 public void addView(View child, int index) { 225 if (getChildCount() > 0) { 226 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 227 } 228 229 super.addView(child, index); 230 } 231 232 @Override addView(View child, ViewGroup.LayoutParams params)233 public void addView(View child, ViewGroup.LayoutParams params) { 234 if (getChildCount() > 0) { 235 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 236 } 237 238 super.addView(child, params); 239 } 240 241 @Override addView(View child, int index, ViewGroup.LayoutParams params)242 public void addView(View child, int index, ViewGroup.LayoutParams params) { 243 if (getChildCount() > 0) { 244 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 245 } 246 247 super.addView(child, index, params); 248 } 249 250 /** 251 * @return Returns true this HorizontalScrollView can be scrolled 252 */ canScroll()253 private boolean canScroll() { 254 View child = getChildAt(0); 255 if (child != null) { 256 int childWidth = child.getWidth(); 257 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 258 } 259 return false; 260 } 261 262 /** 263 * Indicates whether this ScrollView's content is stretched to fill the viewport. 264 * 265 * @return True if the content fills the viewport, false otherwise. 266 */ isFillViewport()267 public boolean isFillViewport() { 268 return mFillViewport; 269 } 270 271 /** 272 * Indicates this ScrollView whether it should stretch its content width to fill 273 * the viewport or not. 274 * 275 * @param fillViewport True to stretch the content's width to the viewport's 276 * boundaries, false otherwise. 277 */ setFillViewport(boolean fillViewport)278 public void setFillViewport(boolean fillViewport) { 279 if (fillViewport != mFillViewport) { 280 mFillViewport = fillViewport; 281 requestLayout(); 282 } 283 } 284 285 /** 286 * @return Whether arrow scrolling will animate its transition. 287 */ isSmoothScrollingEnabled()288 public boolean isSmoothScrollingEnabled() { 289 return mSmoothScrollingEnabled; 290 } 291 292 /** 293 * Set whether arrow scrolling will animate its transition. 294 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 295 */ setSmoothScrollingEnabled(boolean smoothScrollingEnabled)296 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 297 mSmoothScrollingEnabled = smoothScrollingEnabled; 298 } 299 300 @Override onMeasure(int widthMeasureSpec, int heightMeasureSpec)301 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 302 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 303 304 if (!mFillViewport) { 305 return; 306 } 307 308 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 309 if (widthMode == MeasureSpec.UNSPECIFIED) { 310 return; 311 } 312 313 if (getChildCount() > 0) { 314 final View child = getChildAt(0); 315 int width = getMeasuredWidth(); 316 if (child.getMeasuredWidth() < width) { 317 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 318 319 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 320 + mPaddingBottom, lp.height); 321 width -= mPaddingLeft; 322 width -= mPaddingRight; 323 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 324 325 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 326 } 327 } 328 } 329 330 @Override dispatchKeyEvent(KeyEvent event)331 public boolean dispatchKeyEvent(KeyEvent event) { 332 // Let the focused view and/or our descendants get the key first 333 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 334 } 335 336 /** 337 * You can call this function yourself to have the scroll view perform 338 * scrolling from a key event, just as if the event had been dispatched to 339 * it by the view hierarchy. 340 * 341 * @param event The key event to execute. 342 * @return Return true if the event was handled, else false. 343 */ executeKeyEvent(KeyEvent event)344 public boolean executeKeyEvent(KeyEvent event) { 345 mTempRect.setEmpty(); 346 347 if (!canScroll()) { 348 if (isFocused()) { 349 View currentFocused = findFocus(); 350 if (currentFocused == this) currentFocused = null; 351 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 352 currentFocused, View.FOCUS_RIGHT); 353 return nextFocused != null && nextFocused != this && 354 nextFocused.requestFocus(View.FOCUS_RIGHT); 355 } 356 return false; 357 } 358 359 boolean handled = false; 360 if (event.getAction() == KeyEvent.ACTION_DOWN) { 361 switch (event.getKeyCode()) { 362 case KeyEvent.KEYCODE_DPAD_LEFT: 363 if (!event.isAltPressed()) { 364 handled = arrowScroll(View.FOCUS_LEFT); 365 } else { 366 handled = fullScroll(View.FOCUS_LEFT); 367 } 368 break; 369 case KeyEvent.KEYCODE_DPAD_RIGHT: 370 if (!event.isAltPressed()) { 371 handled = arrowScroll(View.FOCUS_RIGHT); 372 } else { 373 handled = fullScroll(View.FOCUS_RIGHT); 374 } 375 break; 376 case KeyEvent.KEYCODE_SPACE: 377 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 378 break; 379 } 380 } 381 382 return handled; 383 } 384 inChild(int x, int y)385 private boolean inChild(int x, int y) { 386 if (getChildCount() > 0) { 387 final int scrollX = mScrollX; 388 final View child = getChildAt(0); 389 return !(y < child.getTop() 390 || y >= child.getBottom() 391 || x < child.getLeft() - scrollX 392 || x >= child.getRight() - scrollX); 393 } 394 return false; 395 } 396 397 @Override onInterceptTouchEvent(MotionEvent ev)398 public boolean onInterceptTouchEvent(MotionEvent ev) { 399 /* 400 * This method JUST determines whether we want to intercept the motion. 401 * If we return true, onMotionEvent will be called and we do the actual 402 * scrolling there. 403 */ 404 405 /* 406 * Shortcut the most recurring case: the user is in the dragging 407 * state and he is moving his finger. We want to intercept this 408 * motion. 409 */ 410 final int action = ev.getAction(); 411 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 412 return true; 413 } 414 415 switch (action & MotionEvent.ACTION_MASK) { 416 case MotionEvent.ACTION_MOVE: { 417 /* 418 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 419 * whether the user has moved far enough from his original down touch. 420 */ 421 422 /* 423 * Locally do absolute value. mLastMotionX is set to the x value 424 * of the down event. 425 */ 426 final int activePointerId = mActivePointerId; 427 if (activePointerId == INVALID_POINTER) { 428 // If we don't have a valid id, the touch down wasn't on content. 429 break; 430 } 431 432 final int pointerIndex = ev.findPointerIndex(activePointerId); 433 final float x = ev.getX(pointerIndex); 434 final int xDiff = (int) Math.abs(x - mLastMotionX); 435 if (xDiff > mTouchSlop) { 436 mIsBeingDragged = true; 437 mLastMotionX = x; 438 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 439 } 440 break; 441 } 442 443 case MotionEvent.ACTION_DOWN: { 444 final float x = ev.getX(); 445 if (!inChild((int) x, (int) ev.getY())) { 446 mIsBeingDragged = false; 447 break; 448 } 449 450 /* 451 * Remember location of down touch. 452 * ACTION_DOWN always refers to pointer index 0. 453 */ 454 mLastMotionX = x; 455 mActivePointerId = ev.getPointerId(0); 456 457 /* 458 * If being flinged and user touches the screen, initiate drag; 459 * otherwise don't. mScroller.isFinished should be false when 460 * being flinged. 461 */ 462 mIsBeingDragged = !mScroller.isFinished(); 463 break; 464 } 465 466 case MotionEvent.ACTION_CANCEL: 467 case MotionEvent.ACTION_UP: 468 /* Release the drag */ 469 mIsBeingDragged = false; 470 mActivePointerId = INVALID_POINTER; 471 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 472 invalidate(); 473 } 474 break; 475 case MotionEvent.ACTION_POINTER_UP: 476 onSecondaryPointerUp(ev); 477 break; 478 } 479 480 /* 481 * The only time we want to intercept motion events is if we are in the 482 * drag mode. 483 */ 484 return mIsBeingDragged; 485 } 486 487 @Override onTouchEvent(MotionEvent ev)488 public boolean onTouchEvent(MotionEvent ev) { 489 490 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 491 // Don't handle edge touches immediately -- they may actually belong to one of our 492 // descendants. 493 return false; 494 } 495 496 if (mVelocityTracker == null) { 497 mVelocityTracker = VelocityTracker.obtain(); 498 } 499 mVelocityTracker.addMovement(ev); 500 501 final int action = ev.getAction(); 502 503 switch (action & MotionEvent.ACTION_MASK) { 504 case MotionEvent.ACTION_DOWN: { 505 mIsBeingDragged = getChildCount() != 0; 506 if (!mIsBeingDragged) { 507 return false; 508 } 509 510 /* 511 * If being flinged and user touches, stop the fling. isFinished 512 * will be false if being flinged. 513 */ 514 if (!mScroller.isFinished()) { 515 mScroller.abortAnimation(); 516 } 517 518 // Remember where the motion event started 519 mLastMotionX = ev.getX(); 520 mActivePointerId = ev.getPointerId(0); 521 break; 522 } 523 case MotionEvent.ACTION_MOVE: 524 if (mIsBeingDragged) { 525 // Scroll to follow the motion event 526 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 527 final float x = ev.getX(activePointerIndex); 528 final int deltaX = (int) (mLastMotionX - x); 529 mLastMotionX = x; 530 531 final int oldX = mScrollX; 532 final int oldY = mScrollY; 533 final int range = getScrollRange(); 534 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 535 mOverscrollDistance, 0, true)) { 536 // Break our velocity if we hit a scroll barrier. 537 mVelocityTracker.clear(); 538 } 539 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 540 541 final int overscrollMode = getOverScrollMode(); 542 if (overscrollMode == OVER_SCROLL_ALWAYS || 543 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 544 final int pulledToX = oldX + deltaX; 545 if (pulledToX < 0) { 546 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 547 if (!mEdgeGlowRight.isFinished()) { 548 mEdgeGlowRight.onRelease(); 549 } 550 } else if (pulledToX > range) { 551 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 552 if (!mEdgeGlowLeft.isFinished()) { 553 mEdgeGlowLeft.onRelease(); 554 } 555 } 556 if (mEdgeGlowLeft != null 557 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 558 invalidate(); 559 } 560 } 561 } 562 break; 563 case MotionEvent.ACTION_UP: 564 if (mIsBeingDragged) { 565 final VelocityTracker velocityTracker = mVelocityTracker; 566 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 567 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 568 569 if (getChildCount() > 0) { 570 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 571 fling(-initialVelocity); 572 } else { 573 final int right = getScrollRange(); 574 if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { 575 invalidate(); 576 } 577 } 578 } 579 580 mActivePointerId = INVALID_POINTER; 581 mIsBeingDragged = false; 582 583 if (mVelocityTracker != null) { 584 mVelocityTracker.recycle(); 585 mVelocityTracker = null; 586 } 587 if (mEdgeGlowLeft != null) { 588 mEdgeGlowLeft.onRelease(); 589 mEdgeGlowRight.onRelease(); 590 } 591 } 592 break; 593 case MotionEvent.ACTION_CANCEL: 594 if (mIsBeingDragged && getChildCount() > 0) { 595 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 596 invalidate(); 597 } 598 mActivePointerId = INVALID_POINTER; 599 mIsBeingDragged = false; 600 if (mVelocityTracker != null) { 601 mVelocityTracker.recycle(); 602 mVelocityTracker = null; 603 } 604 if (mEdgeGlowLeft != null) { 605 mEdgeGlowLeft.onRelease(); 606 mEdgeGlowRight.onRelease(); 607 } 608 } 609 break; 610 case MotionEvent.ACTION_POINTER_UP: 611 onSecondaryPointerUp(ev); 612 break; 613 } 614 return true; 615 } 616 onSecondaryPointerUp(MotionEvent ev)617 private void onSecondaryPointerUp(MotionEvent ev) { 618 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 619 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 620 final int pointerId = ev.getPointerId(pointerIndex); 621 if (pointerId == mActivePointerId) { 622 // This was our active pointer going up. Choose a new 623 // active pointer and adjust accordingly. 624 // TODO: Make this decision more intelligent. 625 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 626 mLastMotionX = ev.getX(newPointerIndex); 627 mActivePointerId = ev.getPointerId(newPointerIndex); 628 if (mVelocityTracker != null) { 629 mVelocityTracker.clear(); 630 } 631 } 632 } 633 634 @Override onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY)635 protected void onOverScrolled(int scrollX, int scrollY, 636 boolean clampedX, boolean clampedY) { 637 // Treat animating scrolls differently; see #computeScroll() for why. 638 if (!mScroller.isFinished()) { 639 mScrollX = scrollX; 640 mScrollY = scrollY; 641 if (clampedX) { 642 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 643 } 644 } else { 645 super.scrollTo(scrollX, scrollY); 646 } 647 awakenScrollBars(); 648 } 649 getScrollRange()650 private int getScrollRange() { 651 int scrollRange = 0; 652 if (getChildCount() > 0) { 653 View child = getChildAt(0); 654 scrollRange = Math.max(0, 655 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 656 } 657 return scrollRange; 658 } 659 660 /** 661 * <p> 662 * Finds the next focusable component that fits in this View's bounds 663 * (excluding fading edges) pretending that this View's left is located at 664 * the parameter left. 665 * </p> 666 * 667 * @param leftFocus look for a candidate is the one at the left of the bounds 668 * if leftFocus is true, or at the right of the bounds if leftFocus 669 * is false 670 * @param left the left offset of the bounds in which a focusable must be 671 * found (the fading edge is assumed to start at this position) 672 * @param preferredFocusable the View that has highest priority and will be 673 * returned if it is within my bounds (null is valid) 674 * @return the next focusable component in the bounds or null if none can be found 675 */ findFocusableViewInMyBounds(final boolean leftFocus, final int left, View preferredFocusable)676 private View findFocusableViewInMyBounds(final boolean leftFocus, 677 final int left, View preferredFocusable) { 678 /* 679 * The fading edge's transparent side should be considered for focus 680 * since it's mostly visible, so we divide the actual fading edge length 681 * by 2. 682 */ 683 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 684 final int leftWithoutFadingEdge = left + fadingEdgeLength; 685 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 686 687 if ((preferredFocusable != null) 688 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 689 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 690 return preferredFocusable; 691 } 692 693 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 694 rightWithoutFadingEdge); 695 } 696 697 /** 698 * <p> 699 * Finds the next focusable component that fits in the specified bounds. 700 * </p> 701 * 702 * @param leftFocus look for a candidate is the one at the left of the bounds 703 * if leftFocus is true, or at the right of the bounds if 704 * leftFocus is false 705 * @param left the left offset of the bounds in which a focusable must be 706 * found 707 * @param right the right offset of the bounds in which a focusable must 708 * be found 709 * @return the next focusable component in the bounds or null if none can 710 * be found 711 */ findFocusableViewInBounds(boolean leftFocus, int left, int right)712 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 713 714 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 715 View focusCandidate = null; 716 717 /* 718 * A fully contained focusable is one where its left is below the bound's 719 * left, and its right is above the bound's right. A partially 720 * contained focusable is one where some part of it is within the 721 * bounds, but it also has some part that is not within bounds. A fully contained 722 * focusable is preferred to a partially contained focusable. 723 */ 724 boolean foundFullyContainedFocusable = false; 725 726 int count = focusables.size(); 727 for (int i = 0; i < count; i++) { 728 View view = focusables.get(i); 729 int viewLeft = view.getLeft(); 730 int viewRight = view.getRight(); 731 732 if (left < viewRight && viewLeft < right) { 733 /* 734 * the focusable is in the target area, it is a candidate for 735 * focusing 736 */ 737 738 final boolean viewIsFullyContained = (left < viewLeft) && 739 (viewRight < right); 740 741 if (focusCandidate == null) { 742 /* No candidate, take this one */ 743 focusCandidate = view; 744 foundFullyContainedFocusable = viewIsFullyContained; 745 } else { 746 final boolean viewIsCloserToBoundary = 747 (leftFocus && viewLeft < focusCandidate.getLeft()) || 748 (!leftFocus && viewRight > focusCandidate.getRight()); 749 750 if (foundFullyContainedFocusable) { 751 if (viewIsFullyContained && viewIsCloserToBoundary) { 752 /* 753 * We're dealing with only fully contained views, so 754 * it has to be closer to the boundary to beat our 755 * candidate 756 */ 757 focusCandidate = view; 758 } 759 } else { 760 if (viewIsFullyContained) { 761 /* Any fully contained view beats a partially contained view */ 762 focusCandidate = view; 763 foundFullyContainedFocusable = true; 764 } else if (viewIsCloserToBoundary) { 765 /* 766 * Partially contained view beats another partially 767 * contained view if it's closer 768 */ 769 focusCandidate = view; 770 } 771 } 772 } 773 } 774 } 775 776 return focusCandidate; 777 } 778 779 /** 780 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 781 * method will scroll the view by one page left or right and give the focus 782 * to the leftmost/rightmost component in the new visible area. If no 783 * component is a good candidate for focus, this scrollview reclaims the 784 * focus.</p> 785 * 786 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 787 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 788 * to go one page right 789 * @return true if the key event is consumed by this method, false otherwise 790 */ pageScroll(int direction)791 public boolean pageScroll(int direction) { 792 boolean right = direction == View.FOCUS_RIGHT; 793 int width = getWidth(); 794 795 if (right) { 796 mTempRect.left = getScrollX() + width; 797 int count = getChildCount(); 798 if (count > 0) { 799 View view = getChildAt(0); 800 if (mTempRect.left + width > view.getRight()) { 801 mTempRect.left = view.getRight() - width; 802 } 803 } 804 } else { 805 mTempRect.left = getScrollX() - width; 806 if (mTempRect.left < 0) { 807 mTempRect.left = 0; 808 } 809 } 810 mTempRect.right = mTempRect.left + width; 811 812 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 813 } 814 815 /** 816 * <p>Handles scrolling in response to a "home/end" shortcut press. This 817 * method will scroll the view to the left or right and give the focus 818 * to the leftmost/rightmost component in the new visible area. If no 819 * component is a good candidate for focus, this scrollview reclaims the 820 * focus.</p> 821 * 822 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 823 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 824 * to go the right 825 * @return true if the key event is consumed by this method, false otherwise 826 */ fullScroll(int direction)827 public boolean fullScroll(int direction) { 828 boolean right = direction == View.FOCUS_RIGHT; 829 int width = getWidth(); 830 831 mTempRect.left = 0; 832 mTempRect.right = width; 833 834 if (right) { 835 int count = getChildCount(); 836 if (count > 0) { 837 View view = getChildAt(0); 838 mTempRect.right = view.getRight(); 839 mTempRect.left = mTempRect.right - width; 840 } 841 } 842 843 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 844 } 845 846 /** 847 * <p>Scrolls the view to make the area defined by <code>left</code> and 848 * <code>right</code> visible. This method attempts to give the focus 849 * to a component visible in this area. If no component can be focused in 850 * the new visible area, the focus is reclaimed by this scrollview.</p> 851 * 852 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 853 * to go left {@link android.view.View#FOCUS_RIGHT} to right 854 * @param left the left offset of the new area to be made visible 855 * @param right the right offset of the new area to be made visible 856 * @return true if the key event is consumed by this method, false otherwise 857 */ scrollAndFocus(int direction, int left, int right)858 private boolean scrollAndFocus(int direction, int left, int right) { 859 boolean handled = true; 860 861 int width = getWidth(); 862 int containerLeft = getScrollX(); 863 int containerRight = containerLeft + width; 864 boolean goLeft = direction == View.FOCUS_LEFT; 865 866 View newFocused = findFocusableViewInBounds(goLeft, left, right); 867 if (newFocused == null) { 868 newFocused = this; 869 } 870 871 if (left >= containerLeft && right <= containerRight) { 872 handled = false; 873 } else { 874 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 875 doScrollX(delta); 876 } 877 878 if (newFocused != findFocus() && newFocused.requestFocus(direction)) { 879 mScrollViewMovedFocus = true; 880 mScrollViewMovedFocus = false; 881 } 882 883 return handled; 884 } 885 886 /** 887 * Handle scrolling in response to a left or right arrow click. 888 * 889 * @param direction The direction corresponding to the arrow key that was 890 * pressed 891 * @return True if we consumed the event, false otherwise 892 */ arrowScroll(int direction)893 public boolean arrowScroll(int direction) { 894 895 View currentFocused = findFocus(); 896 if (currentFocused == this) currentFocused = null; 897 898 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 899 900 final int maxJump = getMaxScrollAmount(); 901 902 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 903 nextFocused.getDrawingRect(mTempRect); 904 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 905 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 906 doScrollX(scrollDelta); 907 nextFocused.requestFocus(direction); 908 } else { 909 // no new focus 910 int scrollDelta = maxJump; 911 912 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 913 scrollDelta = getScrollX(); 914 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 915 916 int daRight = getChildAt(0).getRight(); 917 918 int screenRight = getScrollX() + getWidth(); 919 920 if (daRight - screenRight < maxJump) { 921 scrollDelta = daRight - screenRight; 922 } 923 } 924 if (scrollDelta == 0) { 925 return false; 926 } 927 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 928 } 929 930 if (currentFocused != null && currentFocused.isFocused() 931 && isOffScreen(currentFocused)) { 932 // previously focused item still has focus and is off screen, give 933 // it up (take it back to ourselves) 934 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 935 // sure to 936 // get it) 937 final int descendantFocusability = getDescendantFocusability(); // save 938 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 939 requestFocus(); 940 setDescendantFocusability(descendantFocusability); // restore 941 } 942 return true; 943 } 944 945 /** 946 * @return whether the descendant of this scroll view is scrolled off 947 * screen. 948 */ isOffScreen(View descendant)949 private boolean isOffScreen(View descendant) { 950 return !isWithinDeltaOfScreen(descendant, 0); 951 } 952 953 /** 954 * @return whether the descendant of this scroll view is within delta 955 * pixels of being on the screen. 956 */ isWithinDeltaOfScreen(View descendant, int delta)957 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 958 descendant.getDrawingRect(mTempRect); 959 offsetDescendantRectToMyCoords(descendant, mTempRect); 960 961 return (mTempRect.right + delta) >= getScrollX() 962 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 963 } 964 965 /** 966 * Smooth scroll by a X delta 967 * 968 * @param delta the number of pixels to scroll by on the X axis 969 */ doScrollX(int delta)970 private void doScrollX(int delta) { 971 if (delta != 0) { 972 if (mSmoothScrollingEnabled) { 973 smoothScrollBy(delta, 0); 974 } else { 975 scrollBy(delta, 0); 976 } 977 } 978 } 979 980 /** 981 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 982 * 983 * @param dx the number of pixels to scroll by on the X axis 984 * @param dy the number of pixels to scroll by on the Y axis 985 */ smoothScrollBy(int dx, int dy)986 public final void smoothScrollBy(int dx, int dy) { 987 if (getChildCount() == 0) { 988 // Nothing to do. 989 return; 990 } 991 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 992 if (duration > ANIMATED_SCROLL_GAP) { 993 final int width = getWidth() - mPaddingRight - mPaddingLeft; 994 final int right = getChildAt(0).getWidth(); 995 final int maxX = Math.max(0, right - width); 996 final int scrollX = mScrollX; 997 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 998 999 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1000 invalidate(); 1001 } else { 1002 if (!mScroller.isFinished()) { 1003 mScroller.abortAnimation(); 1004 } 1005 scrollBy(dx, dy); 1006 } 1007 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1008 } 1009 1010 /** 1011 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1012 * 1013 * @param x the position where to scroll on the X axis 1014 * @param y the position where to scroll on the Y axis 1015 */ smoothScrollTo(int x, int y)1016 public final void smoothScrollTo(int x, int y) { 1017 smoothScrollBy(x - mScrollX, y - mScrollY); 1018 } 1019 1020 /** 1021 * <p>The scroll range of a scroll view is the overall width of all of its 1022 * children.</p> 1023 */ 1024 @Override computeHorizontalScrollRange()1025 protected int computeHorizontalScrollRange() { 1026 final int count = getChildCount(); 1027 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1028 if (count == 0) { 1029 return contentWidth; 1030 } 1031 1032 int scrollRange = getChildAt(0).getRight(); 1033 final int scrollX = mScrollX; 1034 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1035 if (scrollX < 0) { 1036 scrollRange -= scrollX; 1037 } else if (scrollX > overscrollRight) { 1038 scrollRange += scrollX - overscrollRight; 1039 } 1040 1041 return scrollRange; 1042 } 1043 1044 @Override computeHorizontalScrollOffset()1045 protected int computeHorizontalScrollOffset() { 1046 return Math.max(0, super.computeHorizontalScrollOffset()); 1047 } 1048 1049 @Override measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec)1050 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1051 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1052 1053 int childWidthMeasureSpec; 1054 int childHeightMeasureSpec; 1055 1056 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1057 + mPaddingBottom, lp.height); 1058 1059 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1060 1061 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1062 } 1063 1064 @Override measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed)1065 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1066 int parentHeightMeasureSpec, int heightUsed) { 1067 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1068 1069 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1070 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1071 + heightUsed, lp.height); 1072 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1073 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1074 1075 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1076 } 1077 1078 @Override computeScroll()1079 public void computeScroll() { 1080 if (mScroller.computeScrollOffset()) { 1081 // This is called at drawing time by ViewGroup. We don't want to 1082 // re-show the scrollbars at this point, which scrollTo will do, 1083 // so we replicate most of scrollTo here. 1084 // 1085 // It's a little odd to call onScrollChanged from inside the drawing. 1086 // 1087 // It is, except when you remember that computeScroll() is used to 1088 // animate scrolling. So unless we want to defer the onScrollChanged() 1089 // until the end of the animated scrolling, we don't really have a 1090 // choice here. 1091 // 1092 // I agree. The alternative, which I think would be worse, is to post 1093 // something and tell the subclasses later. This is bad because there 1094 // will be a window where mScrollX/Y is different from what the app 1095 // thinks it is. 1096 // 1097 int oldX = mScrollX; 1098 int oldY = mScrollY; 1099 int x = mScroller.getCurrX(); 1100 int y = mScroller.getCurrY(); 1101 1102 if (oldX != x || oldY != y) { 1103 overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, 1104 mOverflingDistance, 0, false); 1105 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1106 1107 final int range = getScrollRange(); 1108 final int overscrollMode = getOverScrollMode(); 1109 if (overscrollMode == OVER_SCROLL_ALWAYS || 1110 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1111 if (x < 0 && oldX >= 0) { 1112 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1113 } else if (x > range && oldX <= range) { 1114 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1115 } 1116 } 1117 } 1118 awakenScrollBars(); 1119 1120 // Keep on drawing until the animation has finished. 1121 postInvalidate(); 1122 } 1123 } 1124 1125 /** 1126 * Scrolls the view to the given child. 1127 * 1128 * @param child the View to scroll to 1129 */ scrollToChild(View child)1130 private void scrollToChild(View child) { 1131 child.getDrawingRect(mTempRect); 1132 1133 /* Offset from child's local coordinates to ScrollView coordinates */ 1134 offsetDescendantRectToMyCoords(child, mTempRect); 1135 1136 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1137 1138 if (scrollDelta != 0) { 1139 scrollBy(scrollDelta, 0); 1140 } 1141 } 1142 1143 /** 1144 * If rect is off screen, scroll just enough to get it (or at least the 1145 * first screen size chunk of it) on screen. 1146 * 1147 * @param rect The rectangle. 1148 * @param immediate True to scroll immediately without animation 1149 * @return true if scrolling was performed 1150 */ scrollToChildRect(Rect rect, boolean immediate)1151 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1152 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1153 final boolean scroll = delta != 0; 1154 if (scroll) { 1155 if (immediate) { 1156 scrollBy(delta, 0); 1157 } else { 1158 smoothScrollBy(delta, 0); 1159 } 1160 } 1161 return scroll; 1162 } 1163 1164 /** 1165 * Compute the amount to scroll in the X direction in order to get 1166 * a rectangle completely on the screen (or, if taller than the screen, 1167 * at least the first screen size chunk of it). 1168 * 1169 * @param rect The rect. 1170 * @return The scroll delta. 1171 */ computeScrollDeltaToGetChildRectOnScreen(Rect rect)1172 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1173 if (getChildCount() == 0) return 0; 1174 1175 int width = getWidth(); 1176 int screenLeft = getScrollX(); 1177 int screenRight = screenLeft + width; 1178 1179 int fadingEdge = getHorizontalFadingEdgeLength(); 1180 1181 // leave room for left fading edge as long as rect isn't at very left 1182 if (rect.left > 0) { 1183 screenLeft += fadingEdge; 1184 } 1185 1186 // leave room for right fading edge as long as rect isn't at very right 1187 if (rect.right < getChildAt(0).getWidth()) { 1188 screenRight -= fadingEdge; 1189 } 1190 1191 int scrollXDelta = 0; 1192 1193 if (rect.right > screenRight && rect.left > screenLeft) { 1194 // need to move right to get it in view: move right just enough so 1195 // that the entire rectangle is in view (or at least the first 1196 // screen size chunk). 1197 1198 if (rect.width() > width) { 1199 // just enough to get screen size chunk on 1200 scrollXDelta += (rect.left - screenLeft); 1201 } else { 1202 // get entire rect at right of screen 1203 scrollXDelta += (rect.right - screenRight); 1204 } 1205 1206 // make sure we aren't scrolling beyond the end of our content 1207 int right = getChildAt(0).getRight(); 1208 int distanceToRight = right - screenRight; 1209 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1210 1211 } else if (rect.left < screenLeft && rect.right < screenRight) { 1212 // need to move right to get it in view: move right just enough so that 1213 // entire rectangle is in view (or at least the first screen 1214 // size chunk of it). 1215 1216 if (rect.width() > width) { 1217 // screen size chunk 1218 scrollXDelta -= (screenRight - rect.right); 1219 } else { 1220 // entire rect at left 1221 scrollXDelta -= (screenLeft - rect.left); 1222 } 1223 1224 // make sure we aren't scrolling any further than the left our content 1225 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1226 } 1227 return scrollXDelta; 1228 } 1229 1230 @Override requestChildFocus(View child, View focused)1231 public void requestChildFocus(View child, View focused) { 1232 if (!mScrollViewMovedFocus) { 1233 if (!mIsLayoutDirty) { 1234 scrollToChild(focused); 1235 } else { 1236 // The child may not be laid out yet, we can't compute the scroll yet 1237 mChildToScrollTo = focused; 1238 } 1239 } 1240 super.requestChildFocus(child, focused); 1241 } 1242 1243 1244 /** 1245 * When looking for focus in children of a scroll view, need to be a little 1246 * more careful not to give focus to something that is scrolled off screen. 1247 * 1248 * This is more expensive than the default {@link android.view.ViewGroup} 1249 * implementation, otherwise this behavior might have been made the default. 1250 */ 1251 @Override onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect)1252 protected boolean onRequestFocusInDescendants(int direction, 1253 Rect previouslyFocusedRect) { 1254 1255 // convert from forward / backward notation to up / down / left / right 1256 // (ugh). 1257 if (direction == View.FOCUS_FORWARD) { 1258 direction = View.FOCUS_RIGHT; 1259 } else if (direction == View.FOCUS_BACKWARD) { 1260 direction = View.FOCUS_LEFT; 1261 } 1262 1263 final View nextFocus = previouslyFocusedRect == null ? 1264 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1265 FocusFinder.getInstance().findNextFocusFromRect(this, 1266 previouslyFocusedRect, direction); 1267 1268 if (nextFocus == null) { 1269 return false; 1270 } 1271 1272 if (isOffScreen(nextFocus)) { 1273 return false; 1274 } 1275 1276 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1277 } 1278 1279 @Override requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate)1280 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1281 boolean immediate) { 1282 // offset into coordinate space of this scroll view 1283 rectangle.offset(child.getLeft() - child.getScrollX(), 1284 child.getTop() - child.getScrollY()); 1285 1286 return scrollToChildRect(rectangle, immediate); 1287 } 1288 1289 @Override requestLayout()1290 public void requestLayout() { 1291 mIsLayoutDirty = true; 1292 super.requestLayout(); 1293 } 1294 1295 @Override onLayout(boolean changed, int l, int t, int r, int b)1296 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1297 super.onLayout(changed, l, t, r, b); 1298 mIsLayoutDirty = false; 1299 // Give a child focus if it needs it 1300 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1301 scrollToChild(mChildToScrollTo); 1302 } 1303 mChildToScrollTo = null; 1304 1305 // Calling this with the present values causes it to re-clam them 1306 scrollTo(mScrollX, mScrollY); 1307 } 1308 1309 @Override onSizeChanged(int w, int h, int oldw, int oldh)1310 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1311 super.onSizeChanged(w, h, oldw, oldh); 1312 1313 View currentFocused = findFocus(); 1314 if (null == currentFocused || this == currentFocused) 1315 return; 1316 1317 final int maxJump = mRight - mLeft; 1318 1319 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1320 currentFocused.getDrawingRect(mTempRect); 1321 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1322 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1323 doScrollX(scrollDelta); 1324 } 1325 } 1326 1327 /** 1328 * Return true if child is an descendant of parent, (or equal to the parent). 1329 */ isViewDescendantOf(View child, View parent)1330 private boolean isViewDescendantOf(View child, View parent) { 1331 if (child == parent) { 1332 return true; 1333 } 1334 1335 final ViewParent theParent = child.getParent(); 1336 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1337 } 1338 1339 /** 1340 * Fling the scroll view 1341 * 1342 * @param velocityX The initial velocity in the X direction. Positive 1343 * numbers mean that the finger/curor is moving down the screen, 1344 * which means we want to scroll towards the left. 1345 */ fling(int velocityX)1346 public void fling(int velocityX) { 1347 if (getChildCount() > 0) { 1348 int width = getWidth() - mPaddingRight - mPaddingLeft; 1349 int right = getChildAt(0).getWidth(); 1350 1351 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1352 Math.max(0, right - width), 0, 0, width/2, 0); 1353 1354 final boolean movingRight = velocityX > 0; 1355 1356 View newFocused = findFocusableViewInMyBounds(movingRight, 1357 mScroller.getFinalX(), findFocus()); 1358 1359 if (newFocused == null) { 1360 newFocused = this; 1361 } 1362 1363 if (newFocused != findFocus() 1364 && newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT)) { 1365 mScrollViewMovedFocus = true; 1366 mScrollViewMovedFocus = false; 1367 } 1368 1369 invalidate(); 1370 } 1371 } 1372 1373 /** 1374 * {@inheritDoc} 1375 * 1376 * <p>This version also clamps the scrolling to the bounds of our child. 1377 */ scrollTo(int x, int y)1378 public void scrollTo(int x, int y) { 1379 // we rely on the fact the View.scrollBy calls scrollTo. 1380 if (getChildCount() > 0) { 1381 View child = getChildAt(0); 1382 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1383 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1384 if (x != mScrollX || y != mScrollY) { 1385 super.scrollTo(x, y); 1386 } 1387 } 1388 } 1389 1390 @Override setOverScrollMode(int mode)1391 public void setOverScrollMode(int mode) { 1392 if (mode != OVER_SCROLL_NEVER) { 1393 if (mEdgeGlowLeft == null) { 1394 final Resources res = getContext().getResources(); 1395 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1396 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1397 mEdgeGlowLeft = new EdgeGlow(edge, glow); 1398 mEdgeGlowRight = new EdgeGlow(edge, glow); 1399 } 1400 } else { 1401 mEdgeGlowLeft = null; 1402 mEdgeGlowRight = null; 1403 } 1404 super.setOverScrollMode(mode); 1405 } 1406 1407 @Override draw(Canvas canvas)1408 public void draw(Canvas canvas) { 1409 super.draw(canvas); 1410 if (mEdgeGlowLeft != null) { 1411 final int scrollX = mScrollX; 1412 if (!mEdgeGlowLeft.isFinished()) { 1413 final int restoreCount = canvas.save(); 1414 final int height = getHeight(); 1415 1416 canvas.rotate(270); 1417 canvas.translate(-height * 1.5f, Math.min(0, scrollX)); 1418 mEdgeGlowLeft.setSize(getHeight() * 2, getWidth()); 1419 if (mEdgeGlowLeft.draw(canvas)) { 1420 invalidate(); 1421 } 1422 canvas.restoreToCount(restoreCount); 1423 } 1424 if (!mEdgeGlowRight.isFinished()) { 1425 final int restoreCount = canvas.save(); 1426 final int width = getWidth(); 1427 final int height = getHeight(); 1428 1429 canvas.rotate(90); 1430 canvas.translate(-height / 2, -(Math.max(getScrollRange(), scrollX) + width)); 1431 mEdgeGlowRight.setSize(height * 2, width); 1432 if (mEdgeGlowRight.draw(canvas)) { 1433 invalidate(); 1434 } 1435 canvas.restoreToCount(restoreCount); 1436 } 1437 } 1438 } 1439 clamp(int n, int my, int child)1440 private int clamp(int n, int my, int child) { 1441 if (my >= child || n < 0) { 1442 return 0; 1443 } 1444 if ((my + n) > child) { 1445 return child - my; 1446 } 1447 return n; 1448 } 1449 } 1450