HorizontalScrollView.java revision b1297f76351795822c64236c4ce27b97d18e5bca
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.util.AttributeSet; 22import android.graphics.Canvas; 23import android.graphics.Rect; 24import android.graphics.drawable.Drawable; 25import android.view.View; 26import android.view.VelocityTracker; 27import android.view.ViewConfiguration; 28import android.view.ViewGroup; 29import android.view.KeyEvent; 30import android.view.FocusFinder; 31import android.view.MotionEvent; 32import android.view.ViewParent; 33import android.view.animation.AnimationUtils; 34import android.content.Context; 35import android.content.res.Resources; 36import android.content.res.TypedArray; 37 38import java.util.List; 39 40/** 41 * Layout container for a view hierarchy that can be scrolled by the user, 42 * allowing it to be larger than the physical display. A 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 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 63 */ 64public class HorizontalScrollView extends FrameLayout { 65 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 66 67 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 68 69 70 private long mLastScroll; 71 72 private final Rect mTempRect = new Rect(); 73 private OverScroller mScroller; 74 private EdgeGlow mEdgeGlowLeft; 75 private EdgeGlow mEdgeGlowRight; 76 77 /** 78 * Flag to indicate that we are moving focus ourselves. This is so the 79 * code that watches for focus changes initiated outside this ScrollView 80 * knows that it does not have to do anything. 81 */ 82 private boolean mScrollViewMovedFocus; 83 84 /** 85 * Position of the last motion event. 86 */ 87 private float mLastMotionX; 88 89 /** 90 * True when the layout has changed but the traversal has not come through yet. 91 * Ideally the view hierarchy would keep track of this for us. 92 */ 93 private boolean mIsLayoutDirty = true; 94 95 /** 96 * The child to give focus to in the event that a child has requested focus while the 97 * layout is dirty. This prevents the scroll from being wrong if the child has not been 98 * laid out before requesting focus. 99 */ 100 private View mChildToScrollTo = null; 101 102 /** 103 * True if the user is currently dragging this ScrollView around. This is 104 * not the same as 'is being flinged', which can be checked by 105 * mScroller.isFinished() (flinging begins when the user lifts his finger). 106 */ 107 private boolean mIsBeingDragged = false; 108 109 /** 110 * Determines speed during touch scrolling 111 */ 112 private VelocityTracker mVelocityTracker; 113 114 /** 115 * When set to true, the scroll view measure its child to make it fill the currently 116 * visible area. 117 */ 118 private boolean mFillViewport; 119 120 /** 121 * Whether arrow scrolling is animated. 122 */ 123 private boolean mSmoothScrollingEnabled = true; 124 125 private int mTouchSlop; 126 private int mMinimumVelocity; 127 private int mMaximumVelocity; 128 129 private int mOverscrollDistance; 130 private int mOverflingDistance; 131 132 /** 133 * ID of the active pointer. This is used to retain consistency during 134 * drags/flings if multiple pointers are used. 135 */ 136 private int mActivePointerId = INVALID_POINTER; 137 138 /** 139 * Sentinel value for no current active pointer. 140 * Used by {@link #mActivePointerId}. 141 */ 142 private static final int INVALID_POINTER = -1; 143 144 public HorizontalScrollView(Context context) { 145 this(context, null); 146 } 147 148 public HorizontalScrollView(Context context, AttributeSet attrs) { 149 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 150 } 151 152 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 153 super(context, attrs, defStyle); 154 initScrollView(); 155 156 TypedArray a = context.obtainStyledAttributes(attrs, 157 android.R.styleable.HorizontalScrollView, defStyle, 0); 158 159 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 160 161 a.recycle(); 162 } 163 164 @Override 165 protected float getLeftFadingEdgeStrength() { 166 if (getChildCount() == 0) { 167 return 0.0f; 168 } 169 170 final int length = getHorizontalFadingEdgeLength(); 171 if (mScrollX < length) { 172 return mScrollX / (float) length; 173 } 174 175 return 1.0f; 176 } 177 178 @Override 179 protected float getRightFadingEdgeStrength() { 180 if (getChildCount() == 0) { 181 return 0.0f; 182 } 183 184 final int length = getHorizontalFadingEdgeLength(); 185 final int rightEdge = getWidth() - mPaddingRight; 186 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 187 if (span < length) { 188 return span / (float) length; 189 } 190 191 return 1.0f; 192 } 193 194 /** 195 * @return The maximum amount this scroll view will scroll in response to 196 * an arrow event. 197 */ 198 public int getMaxScrollAmount() { 199 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 200 } 201 202 203 private void initScrollView() { 204 mScroller = new OverScroller(getContext()); 205 setFocusable(true); 206 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 207 setWillNotDraw(false); 208 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 209 mTouchSlop = configuration.getScaledTouchSlop(); 210 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 211 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 212 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 213 mOverflingDistance = configuration.getScaledOverflingDistance(); 214 } 215 216 @Override 217 public void addView(View child) { 218 if (getChildCount() > 0) { 219 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 220 } 221 222 super.addView(child); 223 } 224 225 @Override 226 public void addView(View child, int index) { 227 if (getChildCount() > 0) { 228 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 229 } 230 231 super.addView(child, index); 232 } 233 234 @Override 235 public void addView(View child, ViewGroup.LayoutParams params) { 236 if (getChildCount() > 0) { 237 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 238 } 239 240 super.addView(child, params); 241 } 242 243 @Override 244 public void addView(View child, int index, ViewGroup.LayoutParams params) { 245 if (getChildCount() > 0) { 246 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 247 } 248 249 super.addView(child, index, params); 250 } 251 252 /** 253 * @return Returns true this HorizontalScrollView can be scrolled 254 */ 255 private boolean canScroll() { 256 View child = getChildAt(0); 257 if (child != null) { 258 int childWidth = child.getWidth(); 259 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 260 } 261 return false; 262 } 263 264 /** 265 * Indicates whether this HorizontalScrollView's content is stretched to 266 * fill the viewport. 267 * 268 * @return True if the content fills the viewport, false otherwise. 269 * 270 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 271 */ 272 public boolean isFillViewport() { 273 return mFillViewport; 274 } 275 276 /** 277 * Indicates this HorizontalScrollView whether it should stretch its content width 278 * to fill the viewport or not. 279 * 280 * @param fillViewport True to stretch the content's width to the viewport's 281 * boundaries, false otherwise. 282 * 283 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 284 */ 285 public void setFillViewport(boolean fillViewport) { 286 if (fillViewport != mFillViewport) { 287 mFillViewport = fillViewport; 288 requestLayout(); 289 } 290 } 291 292 /** 293 * @return Whether arrow scrolling will animate its transition. 294 */ 295 public boolean isSmoothScrollingEnabled() { 296 return mSmoothScrollingEnabled; 297 } 298 299 /** 300 * Set whether arrow scrolling will animate its transition. 301 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 302 */ 303 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 304 mSmoothScrollingEnabled = smoothScrollingEnabled; 305 } 306 307 @Override 308 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 309 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 310 311 if (!mFillViewport) { 312 return; 313 } 314 315 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 316 if (widthMode == MeasureSpec.UNSPECIFIED) { 317 return; 318 } 319 320 if (getChildCount() > 0) { 321 final View child = getChildAt(0); 322 int width = getMeasuredWidth(); 323 if (child.getMeasuredWidth() < width) { 324 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 325 326 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 327 + mPaddingBottom, lp.height); 328 width -= mPaddingLeft; 329 width -= mPaddingRight; 330 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 331 332 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 333 } 334 } 335 } 336 337 @Override 338 public boolean dispatchKeyEvent(KeyEvent event) { 339 // Let the focused view and/or our descendants get the key first 340 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 341 } 342 343 /** 344 * You can call this function yourself to have the scroll view perform 345 * scrolling from a key event, just as if the event had been dispatched to 346 * it by the view hierarchy. 347 * 348 * @param event The key event to execute. 349 * @return Return true if the event was handled, else false. 350 */ 351 public boolean executeKeyEvent(KeyEvent event) { 352 mTempRect.setEmpty(); 353 354 if (!canScroll()) { 355 if (isFocused()) { 356 View currentFocused = findFocus(); 357 if (currentFocused == this) currentFocused = null; 358 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 359 currentFocused, View.FOCUS_RIGHT); 360 return nextFocused != null && nextFocused != this && 361 nextFocused.requestFocus(View.FOCUS_RIGHT); 362 } 363 return false; 364 } 365 366 boolean handled = false; 367 if (event.getAction() == KeyEvent.ACTION_DOWN) { 368 switch (event.getKeyCode()) { 369 case KeyEvent.KEYCODE_DPAD_LEFT: 370 if (!event.isAltPressed()) { 371 handled = arrowScroll(View.FOCUS_LEFT); 372 } else { 373 handled = fullScroll(View.FOCUS_LEFT); 374 } 375 break; 376 case KeyEvent.KEYCODE_DPAD_RIGHT: 377 if (!event.isAltPressed()) { 378 handled = arrowScroll(View.FOCUS_RIGHT); 379 } else { 380 handled = fullScroll(View.FOCUS_RIGHT); 381 } 382 break; 383 case KeyEvent.KEYCODE_SPACE: 384 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 385 break; 386 } 387 } 388 389 return handled; 390 } 391 392 private boolean inChild(int x, int y) { 393 if (getChildCount() > 0) { 394 final int scrollX = mScrollX; 395 final View child = getChildAt(0); 396 return !(y < child.getTop() 397 || y >= child.getBottom() 398 || x < child.getLeft() - scrollX 399 || x >= child.getRight() - scrollX); 400 } 401 return false; 402 } 403 404 @Override 405 public boolean onInterceptTouchEvent(MotionEvent ev) { 406 /* 407 * This method JUST determines whether we want to intercept the motion. 408 * If we return true, onMotionEvent will be called and we do the actual 409 * scrolling there. 410 */ 411 412 /* 413 * Shortcut the most recurring case: the user is in the dragging 414 * state and he is moving his finger. We want to intercept this 415 * motion. 416 */ 417 final int action = ev.getAction(); 418 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 419 return true; 420 } 421 422 switch (action & MotionEvent.ACTION_MASK) { 423 case MotionEvent.ACTION_MOVE: { 424 /* 425 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 426 * whether the user has moved far enough from his original down touch. 427 */ 428 429 /* 430 * Locally do absolute value. mLastMotionX is set to the x value 431 * of the down event. 432 */ 433 final int activePointerId = mActivePointerId; 434 if (activePointerId == INVALID_POINTER) { 435 // If we don't have a valid id, the touch down wasn't on content. 436 break; 437 } 438 439 final int pointerIndex = ev.findPointerIndex(activePointerId); 440 final float x = ev.getX(pointerIndex); 441 final int xDiff = (int) Math.abs(x - mLastMotionX); 442 if (xDiff > mTouchSlop) { 443 mIsBeingDragged = true; 444 mLastMotionX = x; 445 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 446 } 447 break; 448 } 449 450 case MotionEvent.ACTION_DOWN: { 451 final float x = ev.getX(); 452 if (!inChild((int) x, (int) ev.getY())) { 453 mIsBeingDragged = false; 454 break; 455 } 456 457 /* 458 * Remember location of down touch. 459 * ACTION_DOWN always refers to pointer index 0. 460 */ 461 mLastMotionX = x; 462 mActivePointerId = ev.getPointerId(0); 463 464 /* 465 * If being flinged and user touches the screen, initiate drag; 466 * otherwise don't. mScroller.isFinished should be false when 467 * being flinged. 468 */ 469 mIsBeingDragged = !mScroller.isFinished(); 470 break; 471 } 472 473 case MotionEvent.ACTION_CANCEL: 474 case MotionEvent.ACTION_UP: 475 /* Release the drag */ 476 mIsBeingDragged = false; 477 mActivePointerId = INVALID_POINTER; 478 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 479 invalidate(); 480 } 481 break; 482 case MotionEvent.ACTION_POINTER_UP: 483 onSecondaryPointerUp(ev); 484 break; 485 } 486 487 /* 488 * The only time we want to intercept motion events is if we are in the 489 * drag mode. 490 */ 491 return mIsBeingDragged; 492 } 493 494 @Override 495 public boolean onTouchEvent(MotionEvent ev) { 496 497 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 498 // Don't handle edge touches immediately -- they may actually belong to one of our 499 // descendants. 500 return false; 501 } 502 503 if (mVelocityTracker == null) { 504 mVelocityTracker = VelocityTracker.obtain(); 505 } 506 mVelocityTracker.addMovement(ev); 507 508 final int action = ev.getAction(); 509 510 switch (action & MotionEvent.ACTION_MASK) { 511 case MotionEvent.ACTION_DOWN: { 512 final float x = ev.getX(); 513 mIsBeingDragged = true; 514 515 /* 516 * If being flinged and user touches, stop the fling. isFinished 517 * will be false if being flinged. 518 */ 519 if (!mScroller.isFinished()) { 520 mScroller.abortAnimation(); 521 } 522 523 // Remember where the motion event started 524 mLastMotionX = x; 525 mActivePointerId = ev.getPointerId(0); 526 break; 527 } 528 case MotionEvent.ACTION_MOVE: 529 if (mIsBeingDragged) { 530 // Scroll to follow the motion event 531 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 532 final float x = ev.getX(activePointerIndex); 533 final int deltaX = (int) (mLastMotionX - x); 534 mLastMotionX = x; 535 536 final int oldX = mScrollX; 537 final int oldY = mScrollY; 538 final int range = getScrollRange(); 539 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 540 mOverscrollDistance, 0, true)) { 541 // Break our velocity if we hit a scroll barrier. 542 mVelocityTracker.clear(); 543 } 544 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 545 546 final int overscrollMode = getOverScrollMode(); 547 if (overscrollMode == OVER_SCROLL_ALWAYS || 548 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 549 final int pulledToX = oldX + deltaX; 550 if (pulledToX < 0) { 551 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 552 if (!mEdgeGlowRight.isFinished()) { 553 mEdgeGlowRight.onRelease(); 554 } 555 } else if (pulledToX > range) { 556 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 557 if (!mEdgeGlowLeft.isFinished()) { 558 mEdgeGlowLeft.onRelease(); 559 } 560 } 561 if (mEdgeGlowLeft != null 562 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 563 invalidate(); 564 } 565 } 566 } 567 break; 568 case MotionEvent.ACTION_UP: 569 if (mIsBeingDragged) { 570 final VelocityTracker velocityTracker = mVelocityTracker; 571 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 572 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 573 574 if (getChildCount() > 0) { 575 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 576 fling(-initialVelocity); 577 } else { 578 final int right = getScrollRange(); 579 if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { 580 invalidate(); 581 } 582 } 583 } 584 585 mActivePointerId = INVALID_POINTER; 586 mIsBeingDragged = false; 587 588 if (mVelocityTracker != null) { 589 mVelocityTracker.recycle(); 590 mVelocityTracker = null; 591 } 592 if (mEdgeGlowLeft != null) { 593 mEdgeGlowLeft.onRelease(); 594 mEdgeGlowRight.onRelease(); 595 } 596 } 597 break; 598 case MotionEvent.ACTION_CANCEL: 599 if (mIsBeingDragged && getChildCount() > 0) { 600 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 601 invalidate(); 602 } 603 mActivePointerId = INVALID_POINTER; 604 mIsBeingDragged = false; 605 if (mVelocityTracker != null) { 606 mVelocityTracker.recycle(); 607 mVelocityTracker = null; 608 } 609 if (mEdgeGlowLeft != null) { 610 mEdgeGlowLeft.onRelease(); 611 mEdgeGlowRight.onRelease(); 612 } 613 } 614 break; 615 case MotionEvent.ACTION_POINTER_UP: 616 onSecondaryPointerUp(ev); 617 break; 618 } 619 return true; 620 } 621 622 private void onSecondaryPointerUp(MotionEvent ev) { 623 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 624 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 625 final int pointerId = ev.getPointerId(pointerIndex); 626 if (pointerId == mActivePointerId) { 627 // This was our active pointer going up. Choose a new 628 // active pointer and adjust accordingly. 629 // TODO: Make this decision more intelligent. 630 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 631 mLastMotionX = ev.getX(newPointerIndex); 632 mActivePointerId = ev.getPointerId(newPointerIndex); 633 if (mVelocityTracker != null) { 634 mVelocityTracker.clear(); 635 } 636 } 637 } 638 639 @Override 640 protected void onOverScrolled(int scrollX, int scrollY, 641 boolean clampedX, boolean clampedY) { 642 // Treat animating scrolls differently; see #computeScroll() for why. 643 if (!mScroller.isFinished()) { 644 mScrollX = scrollX; 645 mScrollY = scrollY; 646 if (clampedX) { 647 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 648 } 649 } else { 650 super.scrollTo(scrollX, scrollY); 651 } 652 awakenScrollBars(); 653 } 654 655 private int getScrollRange() { 656 int scrollRange = 0; 657 if (getChildCount() > 0) { 658 View child = getChildAt(0); 659 scrollRange = Math.max(0, 660 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 661 } 662 return scrollRange; 663 } 664 665 /** 666 * <p> 667 * Finds the next focusable component that fits in this View's bounds 668 * (excluding fading edges) pretending that this View's left is located at 669 * the parameter left. 670 * </p> 671 * 672 * @param leftFocus look for a candidate is the one at the left of the bounds 673 * if leftFocus is true, or at the right of the bounds if leftFocus 674 * is false 675 * @param left the left offset of the bounds in which a focusable must be 676 * found (the fading edge is assumed to start at this position) 677 * @param preferredFocusable the View that has highest priority and will be 678 * returned if it is within my bounds (null is valid) 679 * @return the next focusable component in the bounds or null if none can be found 680 */ 681 private View findFocusableViewInMyBounds(final boolean leftFocus, 682 final int left, View preferredFocusable) { 683 /* 684 * The fading edge's transparent side should be considered for focus 685 * since it's mostly visible, so we divide the actual fading edge length 686 * by 2. 687 */ 688 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 689 final int leftWithoutFadingEdge = left + fadingEdgeLength; 690 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 691 692 if ((preferredFocusable != null) 693 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 694 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 695 return preferredFocusable; 696 } 697 698 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 699 rightWithoutFadingEdge); 700 } 701 702 /** 703 * <p> 704 * Finds the next focusable component that fits in the specified bounds. 705 * </p> 706 * 707 * @param leftFocus look for a candidate is the one at the left of the bounds 708 * if leftFocus is true, or at the right of the bounds if 709 * leftFocus is false 710 * @param left the left offset of the bounds in which a focusable must be 711 * found 712 * @param right the right offset of the bounds in which a focusable must 713 * be found 714 * @return the next focusable component in the bounds or null if none can 715 * be found 716 */ 717 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 718 719 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 720 View focusCandidate = null; 721 722 /* 723 * A fully contained focusable is one where its left is below the bound's 724 * left, and its right is above the bound's right. A partially 725 * contained focusable is one where some part of it is within the 726 * bounds, but it also has some part that is not within bounds. A fully contained 727 * focusable is preferred to a partially contained focusable. 728 */ 729 boolean foundFullyContainedFocusable = false; 730 731 int count = focusables.size(); 732 for (int i = 0; i < count; i++) { 733 View view = focusables.get(i); 734 int viewLeft = view.getLeft(); 735 int viewRight = view.getRight(); 736 737 if (left < viewRight && viewLeft < right) { 738 /* 739 * the focusable is in the target area, it is a candidate for 740 * focusing 741 */ 742 743 final boolean viewIsFullyContained = (left < viewLeft) && 744 (viewRight < right); 745 746 if (focusCandidate == null) { 747 /* No candidate, take this one */ 748 focusCandidate = view; 749 foundFullyContainedFocusable = viewIsFullyContained; 750 } else { 751 final boolean viewIsCloserToBoundary = 752 (leftFocus && viewLeft < focusCandidate.getLeft()) || 753 (!leftFocus && viewRight > focusCandidate.getRight()); 754 755 if (foundFullyContainedFocusable) { 756 if (viewIsFullyContained && viewIsCloserToBoundary) { 757 /* 758 * We're dealing with only fully contained views, so 759 * it has to be closer to the boundary to beat our 760 * candidate 761 */ 762 focusCandidate = view; 763 } 764 } else { 765 if (viewIsFullyContained) { 766 /* Any fully contained view beats a partially contained view */ 767 focusCandidate = view; 768 foundFullyContainedFocusable = true; 769 } else if (viewIsCloserToBoundary) { 770 /* 771 * Partially contained view beats another partially 772 * contained view if it's closer 773 */ 774 focusCandidate = view; 775 } 776 } 777 } 778 } 779 } 780 781 return focusCandidate; 782 } 783 784 /** 785 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 786 * method will scroll the view by one page left or right and give the focus 787 * to the leftmost/rightmost component in the new visible area. If no 788 * component is a good candidate for focus, this scrollview reclaims the 789 * focus.</p> 790 * 791 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 792 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 793 * to go one page right 794 * @return true if the key event is consumed by this method, false otherwise 795 */ 796 public boolean pageScroll(int direction) { 797 boolean right = direction == View.FOCUS_RIGHT; 798 int width = getWidth(); 799 800 if (right) { 801 mTempRect.left = getScrollX() + width; 802 int count = getChildCount(); 803 if (count > 0) { 804 View view = getChildAt(0); 805 if (mTempRect.left + width > view.getRight()) { 806 mTempRect.left = view.getRight() - width; 807 } 808 } 809 } else { 810 mTempRect.left = getScrollX() - width; 811 if (mTempRect.left < 0) { 812 mTempRect.left = 0; 813 } 814 } 815 mTempRect.right = mTempRect.left + width; 816 817 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 818 } 819 820 /** 821 * <p>Handles scrolling in response to a "home/end" shortcut press. This 822 * method will scroll the view to the left or right and give the focus 823 * to the leftmost/rightmost component in the new visible area. If no 824 * component is a good candidate for focus, this scrollview reclaims the 825 * focus.</p> 826 * 827 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 828 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 829 * to go the right 830 * @return true if the key event is consumed by this method, false otherwise 831 */ 832 public boolean fullScroll(int direction) { 833 boolean right = direction == View.FOCUS_RIGHT; 834 int width = getWidth(); 835 836 mTempRect.left = 0; 837 mTempRect.right = width; 838 839 if (right) { 840 int count = getChildCount(); 841 if (count > 0) { 842 View view = getChildAt(0); 843 mTempRect.right = view.getRight(); 844 mTempRect.left = mTempRect.right - width; 845 } 846 } 847 848 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 849 } 850 851 /** 852 * <p>Scrolls the view to make the area defined by <code>left</code> and 853 * <code>right</code> visible. This method attempts to give the focus 854 * to a component visible in this area. If no component can be focused in 855 * the new visible area, the focus is reclaimed by this scrollview.</p> 856 * 857 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 858 * to go left {@link android.view.View#FOCUS_RIGHT} to right 859 * @param left the left offset of the new area to be made visible 860 * @param right the right offset of the new area to be made visible 861 * @return true if the key event is consumed by this method, false otherwise 862 */ 863 private boolean scrollAndFocus(int direction, int left, int right) { 864 boolean handled = true; 865 866 int width = getWidth(); 867 int containerLeft = getScrollX(); 868 int containerRight = containerLeft + width; 869 boolean goLeft = direction == View.FOCUS_LEFT; 870 871 View newFocused = findFocusableViewInBounds(goLeft, left, right); 872 if (newFocused == null) { 873 newFocused = this; 874 } 875 876 if (left >= containerLeft && right <= containerRight) { 877 handled = false; 878 } else { 879 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 880 doScrollX(delta); 881 } 882 883 if (newFocused != findFocus() && newFocused.requestFocus(direction)) { 884 mScrollViewMovedFocus = true; 885 mScrollViewMovedFocus = false; 886 } 887 888 return handled; 889 } 890 891 /** 892 * Handle scrolling in response to a left or right arrow click. 893 * 894 * @param direction The direction corresponding to the arrow key that was 895 * pressed 896 * @return True if we consumed the event, false otherwise 897 */ 898 public boolean arrowScroll(int direction) { 899 900 View currentFocused = findFocus(); 901 if (currentFocused == this) currentFocused = null; 902 903 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 904 905 final int maxJump = getMaxScrollAmount(); 906 907 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 908 nextFocused.getDrawingRect(mTempRect); 909 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 910 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 911 doScrollX(scrollDelta); 912 nextFocused.requestFocus(direction); 913 } else { 914 // no new focus 915 int scrollDelta = maxJump; 916 917 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 918 scrollDelta = getScrollX(); 919 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 920 921 int daRight = getChildAt(0).getRight(); 922 923 int screenRight = getScrollX() + getWidth(); 924 925 if (daRight - screenRight < maxJump) { 926 scrollDelta = daRight - screenRight; 927 } 928 } 929 if (scrollDelta == 0) { 930 return false; 931 } 932 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 933 } 934 935 if (currentFocused != null && currentFocused.isFocused() 936 && isOffScreen(currentFocused)) { 937 // previously focused item still has focus and is off screen, give 938 // it up (take it back to ourselves) 939 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 940 // sure to 941 // get it) 942 final int descendantFocusability = getDescendantFocusability(); // save 943 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 944 requestFocus(); 945 setDescendantFocusability(descendantFocusability); // restore 946 } 947 return true; 948 } 949 950 /** 951 * @return whether the descendant of this scroll view is scrolled off 952 * screen. 953 */ 954 private boolean isOffScreen(View descendant) { 955 return !isWithinDeltaOfScreen(descendant, 0); 956 } 957 958 /** 959 * @return whether the descendant of this scroll view is within delta 960 * pixels of being on the screen. 961 */ 962 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 963 descendant.getDrawingRect(mTempRect); 964 offsetDescendantRectToMyCoords(descendant, mTempRect); 965 966 return (mTempRect.right + delta) >= getScrollX() 967 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 968 } 969 970 /** 971 * Smooth scroll by a X delta 972 * 973 * @param delta the number of pixels to scroll by on the X axis 974 */ 975 private void doScrollX(int delta) { 976 if (delta != 0) { 977 if (mSmoothScrollingEnabled) { 978 smoothScrollBy(delta, 0); 979 } else { 980 scrollBy(delta, 0); 981 } 982 } 983 } 984 985 /** 986 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 987 * 988 * @param dx the number of pixels to scroll by on the X axis 989 * @param dy the number of pixels to scroll by on the Y axis 990 */ 991 public final void smoothScrollBy(int dx, int dy) { 992 if (getChildCount() == 0) { 993 // Nothing to do. 994 return; 995 } 996 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 997 if (duration > ANIMATED_SCROLL_GAP) { 998 final int width = getWidth() - mPaddingRight - mPaddingLeft; 999 final int right = getChildAt(0).getWidth(); 1000 final int maxX = Math.max(0, right - width); 1001 final int scrollX = mScrollX; 1002 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1003 1004 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1005 invalidate(); 1006 } else { 1007 if (!mScroller.isFinished()) { 1008 mScroller.abortAnimation(); 1009 } 1010 scrollBy(dx, dy); 1011 } 1012 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1013 } 1014 1015 /** 1016 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1017 * 1018 * @param x the position where to scroll on the X axis 1019 * @param y the position where to scroll on the Y axis 1020 */ 1021 public final void smoothScrollTo(int x, int y) { 1022 smoothScrollBy(x - mScrollX, y - mScrollY); 1023 } 1024 1025 /** 1026 * <p>The scroll range of a scroll view is the overall width of all of its 1027 * children.</p> 1028 */ 1029 @Override 1030 protected int computeHorizontalScrollRange() { 1031 final int count = getChildCount(); 1032 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1033 if (count == 0) { 1034 return contentWidth; 1035 } 1036 1037 int scrollRange = getChildAt(0).getRight(); 1038 final int scrollX = mScrollX; 1039 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1040 if (scrollX < 0) { 1041 scrollRange -= scrollX; 1042 } else if (scrollX > overscrollRight) { 1043 scrollRange += scrollX - overscrollRight; 1044 } 1045 1046 return scrollRange; 1047 } 1048 1049 @Override 1050 protected int computeHorizontalScrollOffset() { 1051 return Math.max(0, super.computeHorizontalScrollOffset()); 1052 } 1053 1054 @Override 1055 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1056 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1057 1058 int childWidthMeasureSpec; 1059 int childHeightMeasureSpec; 1060 1061 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1062 + mPaddingBottom, lp.height); 1063 1064 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1065 1066 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1067 } 1068 1069 @Override 1070 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1071 int parentHeightMeasureSpec, int heightUsed) { 1072 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1073 1074 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1075 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1076 + heightUsed, lp.height); 1077 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1078 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1079 1080 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1081 } 1082 1083 @Override 1084 public void computeScroll() { 1085 if (mScroller.computeScrollOffset()) { 1086 // This is called at drawing time by ViewGroup. We don't want to 1087 // re-show the scrollbars at this point, which scrollTo will do, 1088 // so we replicate most of scrollTo here. 1089 // 1090 // It's a little odd to call onScrollChanged from inside the drawing. 1091 // 1092 // It is, except when you remember that computeScroll() is used to 1093 // animate scrolling. So unless we want to defer the onScrollChanged() 1094 // until the end of the animated scrolling, we don't really have a 1095 // choice here. 1096 // 1097 // I agree. The alternative, which I think would be worse, is to post 1098 // something and tell the subclasses later. This is bad because there 1099 // will be a window where mScrollX/Y is different from what the app 1100 // thinks it is. 1101 // 1102 int oldX = mScrollX; 1103 int oldY = mScrollY; 1104 int x = mScroller.getCurrX(); 1105 int y = mScroller.getCurrY(); 1106 1107 if (oldX != x || oldY != y) { 1108 overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, 1109 mOverflingDistance, 0, false); 1110 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1111 1112 final int range = getScrollRange(); 1113 final int overscrollMode = getOverScrollMode(); 1114 if (overscrollMode == OVER_SCROLL_ALWAYS || 1115 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 1116 if (x < 0 && oldX >= 0) { 1117 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1118 } else if (x > range && oldX <= range) { 1119 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1120 } 1121 } 1122 } 1123 awakenScrollBars(); 1124 1125 // Keep on drawing until the animation has finished. 1126 postInvalidate(); 1127 } 1128 } 1129 1130 /** 1131 * Scrolls the view to the given child. 1132 * 1133 * @param child the View to scroll to 1134 */ 1135 private void scrollToChild(View child) { 1136 child.getDrawingRect(mTempRect); 1137 1138 /* Offset from child's local coordinates to ScrollView coordinates */ 1139 offsetDescendantRectToMyCoords(child, mTempRect); 1140 1141 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1142 1143 if (scrollDelta != 0) { 1144 scrollBy(scrollDelta, 0); 1145 } 1146 } 1147 1148 /** 1149 * If rect is off screen, scroll just enough to get it (or at least the 1150 * first screen size chunk of it) on screen. 1151 * 1152 * @param rect The rectangle. 1153 * @param immediate True to scroll immediately without animation 1154 * @return true if scrolling was performed 1155 */ 1156 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1157 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1158 final boolean scroll = delta != 0; 1159 if (scroll) { 1160 if (immediate) { 1161 scrollBy(delta, 0); 1162 } else { 1163 smoothScrollBy(delta, 0); 1164 } 1165 } 1166 return scroll; 1167 } 1168 1169 /** 1170 * Compute the amount to scroll in the X direction in order to get 1171 * a rectangle completely on the screen (or, if taller than the screen, 1172 * at least the first screen size chunk of it). 1173 * 1174 * @param rect The rect. 1175 * @return The scroll delta. 1176 */ 1177 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1178 if (getChildCount() == 0) return 0; 1179 1180 int width = getWidth(); 1181 int screenLeft = getScrollX(); 1182 int screenRight = screenLeft + width; 1183 1184 int fadingEdge = getHorizontalFadingEdgeLength(); 1185 1186 // leave room for left fading edge as long as rect isn't at very left 1187 if (rect.left > 0) { 1188 screenLeft += fadingEdge; 1189 } 1190 1191 // leave room for right fading edge as long as rect isn't at very right 1192 if (rect.right < getChildAt(0).getWidth()) { 1193 screenRight -= fadingEdge; 1194 } 1195 1196 int scrollXDelta = 0; 1197 1198 if (rect.right > screenRight && rect.left > screenLeft) { 1199 // need to move right to get it in view: move right just enough so 1200 // that the entire rectangle is in view (or at least the first 1201 // screen size chunk). 1202 1203 if (rect.width() > width) { 1204 // just enough to get screen size chunk on 1205 scrollXDelta += (rect.left - screenLeft); 1206 } else { 1207 // get entire rect at right of screen 1208 scrollXDelta += (rect.right - screenRight); 1209 } 1210 1211 // make sure we aren't scrolling beyond the end of our content 1212 int right = getChildAt(0).getRight(); 1213 int distanceToRight = right - screenRight; 1214 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1215 1216 } else if (rect.left < screenLeft && rect.right < screenRight) { 1217 // need to move right to get it in view: move right just enough so that 1218 // entire rectangle is in view (or at least the first screen 1219 // size chunk of it). 1220 1221 if (rect.width() > width) { 1222 // screen size chunk 1223 scrollXDelta -= (screenRight - rect.right); 1224 } else { 1225 // entire rect at left 1226 scrollXDelta -= (screenLeft - rect.left); 1227 } 1228 1229 // make sure we aren't scrolling any further than the left our content 1230 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1231 } 1232 return scrollXDelta; 1233 } 1234 1235 @Override 1236 public void requestChildFocus(View child, View focused) { 1237 if (!mScrollViewMovedFocus) { 1238 if (!mIsLayoutDirty) { 1239 scrollToChild(focused); 1240 } else { 1241 // The child may not be laid out yet, we can't compute the scroll yet 1242 mChildToScrollTo = focused; 1243 } 1244 } 1245 super.requestChildFocus(child, focused); 1246 } 1247 1248 1249 /** 1250 * When looking for focus in children of a scroll view, need to be a little 1251 * more careful not to give focus to something that is scrolled off screen. 1252 * 1253 * This is more expensive than the default {@link android.view.ViewGroup} 1254 * implementation, otherwise this behavior might have been made the default. 1255 */ 1256 @Override 1257 protected boolean onRequestFocusInDescendants(int direction, 1258 Rect previouslyFocusedRect) { 1259 1260 // convert from forward / backward notation to up / down / left / right 1261 // (ugh). 1262 if (direction == View.FOCUS_FORWARD) { 1263 direction = View.FOCUS_RIGHT; 1264 } else if (direction == View.FOCUS_BACKWARD) { 1265 direction = View.FOCUS_LEFT; 1266 } 1267 1268 final View nextFocus = previouslyFocusedRect == null ? 1269 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1270 FocusFinder.getInstance().findNextFocusFromRect(this, 1271 previouslyFocusedRect, direction); 1272 1273 if (nextFocus == null) { 1274 return false; 1275 } 1276 1277 if (isOffScreen(nextFocus)) { 1278 return false; 1279 } 1280 1281 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1282 } 1283 1284 @Override 1285 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1286 boolean immediate) { 1287 // offset into coordinate space of this scroll view 1288 rectangle.offset(child.getLeft() - child.getScrollX(), 1289 child.getTop() - child.getScrollY()); 1290 1291 return scrollToChildRect(rectangle, immediate); 1292 } 1293 1294 @Override 1295 public void requestLayout() { 1296 mIsLayoutDirty = true; 1297 super.requestLayout(); 1298 } 1299 1300 @Override 1301 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1302 super.onLayout(changed, l, t, r, b); 1303 mIsLayoutDirty = false; 1304 // Give a child focus if it needs it 1305 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1306 scrollToChild(mChildToScrollTo); 1307 } 1308 mChildToScrollTo = null; 1309 1310 // Calling this with the present values causes it to re-clam them 1311 scrollTo(mScrollX, mScrollY); 1312 } 1313 1314 @Override 1315 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1316 super.onSizeChanged(w, h, oldw, oldh); 1317 1318 View currentFocused = findFocus(); 1319 if (null == currentFocused || this == currentFocused) 1320 return; 1321 1322 final int maxJump = mRight - mLeft; 1323 1324 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1325 currentFocused.getDrawingRect(mTempRect); 1326 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1327 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1328 doScrollX(scrollDelta); 1329 } 1330 } 1331 1332 /** 1333 * Return true if child is an descendant of parent, (or equal to the parent). 1334 */ 1335 private boolean isViewDescendantOf(View child, View parent) { 1336 if (child == parent) { 1337 return true; 1338 } 1339 1340 final ViewParent theParent = child.getParent(); 1341 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1342 } 1343 1344 /** 1345 * Fling the scroll view 1346 * 1347 * @param velocityX The initial velocity in the X direction. Positive 1348 * numbers mean that the finger/curor is moving down the screen, 1349 * which means we want to scroll towards the left. 1350 */ 1351 public void fling(int velocityX) { 1352 if (getChildCount() > 0) { 1353 int width = getWidth() - mPaddingRight - mPaddingLeft; 1354 int right = getChildAt(0).getWidth(); 1355 1356 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1357 Math.max(0, right - width), 0, 0, width/2, 0); 1358 1359 final boolean movingRight = velocityX > 0; 1360 1361 View newFocused = findFocusableViewInMyBounds(movingRight, 1362 mScroller.getFinalX(), findFocus()); 1363 1364 if (newFocused == null) { 1365 newFocused = this; 1366 } 1367 1368 if (newFocused != findFocus() 1369 && newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT)) { 1370 mScrollViewMovedFocus = true; 1371 mScrollViewMovedFocus = false; 1372 } 1373 1374 invalidate(); 1375 } 1376 } 1377 1378 /** 1379 * {@inheritDoc} 1380 * 1381 * <p>This version also clamps the scrolling to the bounds of our child. 1382 */ 1383 public void scrollTo(int x, int y) { 1384 // we rely on the fact the View.scrollBy calls scrollTo. 1385 if (getChildCount() > 0) { 1386 View child = getChildAt(0); 1387 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1388 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1389 if (x != mScrollX || y != mScrollY) { 1390 super.scrollTo(x, y); 1391 } 1392 } 1393 } 1394 1395 @Override 1396 public void setOverScrollMode(int mode) { 1397 if (mode != OVER_SCROLL_NEVER) { 1398 if (mEdgeGlowLeft == null) { 1399 Context context = getContext(); 1400 final Resources res = context.getResources(); 1401 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1402 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1403 mEdgeGlowLeft = new EdgeGlow(context, edge, glow); 1404 mEdgeGlowRight = new EdgeGlow(context, edge, glow); 1405 } 1406 } else { 1407 mEdgeGlowLeft = null; 1408 mEdgeGlowRight = null; 1409 } 1410 super.setOverScrollMode(mode); 1411 } 1412 1413 @Override 1414 public void draw(Canvas canvas) { 1415 super.draw(canvas); 1416 if (mEdgeGlowLeft != null) { 1417 final int scrollX = mScrollX; 1418 if (!mEdgeGlowLeft.isFinished()) { 1419 final int restoreCount = canvas.save(); 1420 final int height = getHeight(); 1421 1422 canvas.rotate(270); 1423 canvas.translate(-height, Math.min(0, scrollX)); 1424 mEdgeGlowLeft.setSize(getHeight(), getWidth()); 1425 if (mEdgeGlowLeft.draw(canvas)) { 1426 invalidate(); 1427 } 1428 canvas.restoreToCount(restoreCount); 1429 } 1430 if (!mEdgeGlowRight.isFinished()) { 1431 final int restoreCount = canvas.save(); 1432 final int width = getWidth(); 1433 final int height = getHeight(); 1434 1435 canvas.rotate(90); 1436 canvas.translate(0, 1437 -(Math.max(getScrollRange(), scrollX) + width)); 1438 mEdgeGlowRight.setSize(height, width); 1439 if (mEdgeGlowRight.draw(canvas)) { 1440 invalidate(); 1441 } 1442 canvas.restoreToCount(restoreCount); 1443 } 1444 } 1445 } 1446 1447 private int clamp(int n, int my, int child) { 1448 if (my >= child || n < 0) { 1449 return 0; 1450 } 1451 if ((my + n) > child) { 1452 return child - my; 1453 } 1454 return n; 1455 } 1456} 1457