HorizontalScrollView.java revision 2ed2eacd7e0569675410f1e62238b708c5dcc8ac
1/* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.widget; 18 19import com.android.internal.R; 20 21import android.content.Context; 22import android.content.res.Resources; 23import android.content.res.TypedArray; 24import android.graphics.Canvas; 25import android.graphics.Rect; 26import android.graphics.drawable.Drawable; 27import android.util.AttributeSet; 28import android.view.FocusFinder; 29import android.view.KeyEvent; 30import android.view.MotionEvent; 31import android.view.VelocityTracker; 32import android.view.View; 33import android.view.ViewConfiguration; 34import android.view.ViewDebug; 35import android.view.ViewGroup; 36import android.view.ViewParent; 37import android.view.animation.AnimationUtils; 38 39import java.util.List; 40 41/** 42 * Layout container for a view hierarchy that can be scrolled by the user, 43 * allowing it to be larger than the physical display. A HorizontalScrollView 44 * is a {@link FrameLayout}, meaning you should place one child in it 45 * containing the entire contents to scroll; this child may itself be a layout 46 * manager with a complex hierarchy of objects. A child that is often used 47 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 48 * array of top-level items that the user can scroll through. 49 * 50 * <p>You should never use a HorizontalScrollView with a {@link ListView}, since 51 * ListView takes care of its own scrolling. Most importantly, doing this 52 * defeats all of the important optimizations in ListView for dealing with 53 * large lists, since it effectively forces the ListView to display its entire 54 * list of items to fill up the infinite container supplied by HorizontalScrollView. 55 * 56 * <p>The {@link TextView} class also 57 * takes care of its own scrolling, so does not require a ScrollView, but 58 * using the two together is possible to achieve the effect of a text view 59 * within a larger container. 60 * 61 * <p>HorizontalScrollView only supports horizontal scrolling. 62 * 63 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 64 */ 65public class HorizontalScrollView extends FrameLayout { 66 private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; 67 68 private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; 69 70 71 private long mLastScroll; 72 73 private final Rect mTempRect = new Rect(); 74 private OverScroller mScroller; 75 private EdgeGlow mEdgeGlowLeft; 76 private EdgeGlow mEdgeGlowRight; 77 78 /** 79 * Position of the last motion event. 80 */ 81 private float mLastMotionX; 82 83 /** 84 * True when the layout has changed but the traversal has not come through yet. 85 * Ideally the view hierarchy would keep track of this for us. 86 */ 87 private boolean mIsLayoutDirty = true; 88 89 /** 90 * The child to give focus to in the event that a child has requested focus while the 91 * layout is dirty. This prevents the scroll from being wrong if the child has not been 92 * laid out before requesting focus. 93 */ 94 private View mChildToScrollTo = null; 95 96 /** 97 * True if the user is currently dragging this ScrollView around. This is 98 * not the same as 'is being flinged', which can be checked by 99 * mScroller.isFinished() (flinging begins when the user lifts his finger). 100 */ 101 private boolean mIsBeingDragged = false; 102 103 /** 104 * Determines speed during touch scrolling 105 */ 106 private VelocityTracker mVelocityTracker; 107 108 /** 109 * When set to true, the scroll view measure its child to make it fill the currently 110 * visible area. 111 */ 112 @ViewDebug.ExportedProperty(category = "layout") 113 private boolean mFillViewport; 114 115 /** 116 * Whether arrow scrolling is animated. 117 */ 118 private boolean mSmoothScrollingEnabled = true; 119 120 private int mTouchSlop; 121 private int mMinimumVelocity; 122 private int mMaximumVelocity; 123 124 private int mOverscrollDistance; 125 private int mOverflingDistance; 126 127 /** 128 * ID of the active pointer. This is used to retain consistency during 129 * drags/flings if multiple pointers are used. 130 */ 131 private int mActivePointerId = INVALID_POINTER; 132 133 /** 134 * Sentinel value for no current active pointer. 135 * Used by {@link #mActivePointerId}. 136 */ 137 private static final int INVALID_POINTER = -1; 138 139 public HorizontalScrollView(Context context) { 140 this(context, null); 141 } 142 143 public HorizontalScrollView(Context context, AttributeSet attrs) { 144 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 145 } 146 147 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 148 super(context, attrs, defStyle); 149 initScrollView(); 150 151 TypedArray a = context.obtainStyledAttributes(attrs, 152 android.R.styleable.HorizontalScrollView, defStyle, 0); 153 154 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 155 156 a.recycle(); 157 } 158 159 @Override 160 protected float getLeftFadingEdgeStrength() { 161 if (getChildCount() == 0) { 162 return 0.0f; 163 } 164 165 final int length = getHorizontalFadingEdgeLength(); 166 if (mScrollX < length) { 167 return mScrollX / (float) length; 168 } 169 170 return 1.0f; 171 } 172 173 @Override 174 protected float getRightFadingEdgeStrength() { 175 if (getChildCount() == 0) { 176 return 0.0f; 177 } 178 179 final int length = getHorizontalFadingEdgeLength(); 180 final int rightEdge = getWidth() - mPaddingRight; 181 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 182 if (span < length) { 183 return span / (float) length; 184 } 185 186 return 1.0f; 187 } 188 189 /** 190 * @return The maximum amount this scroll view will scroll in response to 191 * an arrow event. 192 */ 193 public int getMaxScrollAmount() { 194 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 195 } 196 197 198 private void initScrollView() { 199 mScroller = new OverScroller(getContext()); 200 setFocusable(true); 201 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 202 setWillNotDraw(false); 203 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 204 mTouchSlop = configuration.getScaledTouchSlop(); 205 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 206 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 207 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 208 mOverflingDistance = configuration.getScaledOverflingDistance(); 209 } 210 211 @Override 212 public void addView(View child) { 213 if (getChildCount() > 0) { 214 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 215 } 216 217 super.addView(child); 218 } 219 220 @Override 221 public void addView(View child, int index) { 222 if (getChildCount() > 0) { 223 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 224 } 225 226 super.addView(child, index); 227 } 228 229 @Override 230 public void addView(View child, ViewGroup.LayoutParams params) { 231 if (getChildCount() > 0) { 232 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 233 } 234 235 super.addView(child, params); 236 } 237 238 @Override 239 public void addView(View child, int index, ViewGroup.LayoutParams params) { 240 if (getChildCount() > 0) { 241 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 242 } 243 244 super.addView(child, index, params); 245 } 246 247 /** 248 * @return Returns true this HorizontalScrollView can be scrolled 249 */ 250 private boolean canScroll() { 251 View child = getChildAt(0); 252 if (child != null) { 253 int childWidth = child.getWidth(); 254 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 255 } 256 return false; 257 } 258 259 /** 260 * Indicates whether this HorizontalScrollView's content is stretched to 261 * fill the viewport. 262 * 263 * @return True if the content fills the viewport, false otherwise. 264 * 265 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 266 */ 267 public boolean isFillViewport() { 268 return mFillViewport; 269 } 270 271 /** 272 * Indicates this HorizontalScrollView whether it should stretch its content width 273 * to fill the viewport or not. 274 * 275 * @param fillViewport True to stretch the content's width to the viewport's 276 * boundaries, false otherwise. 277 * 278 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 279 */ 280 public void setFillViewport(boolean fillViewport) { 281 if (fillViewport != mFillViewport) { 282 mFillViewport = fillViewport; 283 requestLayout(); 284 } 285 } 286 287 /** 288 * @return Whether arrow scrolling will animate its transition. 289 */ 290 public boolean isSmoothScrollingEnabled() { 291 return mSmoothScrollingEnabled; 292 } 293 294 /** 295 * Set whether arrow scrolling will animate its transition. 296 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 297 */ 298 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 299 mSmoothScrollingEnabled = smoothScrollingEnabled; 300 } 301 302 @Override 303 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 304 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 305 306 if (!mFillViewport) { 307 return; 308 } 309 310 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 311 if (widthMode == MeasureSpec.UNSPECIFIED) { 312 return; 313 } 314 315 if (getChildCount() > 0) { 316 final View child = getChildAt(0); 317 int width = getMeasuredWidth(); 318 if (child.getMeasuredWidth() < width) { 319 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 320 321 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 322 + mPaddingBottom, lp.height); 323 width -= mPaddingLeft; 324 width -= mPaddingRight; 325 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 326 327 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 328 } 329 } 330 } 331 332 @Override 333 public boolean dispatchKeyEvent(KeyEvent event) { 334 // Let the focused view and/or our descendants get the key first 335 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 336 } 337 338 /** 339 * You can call this function yourself to have the scroll view perform 340 * scrolling from a key event, just as if the event had been dispatched to 341 * it by the view hierarchy. 342 * 343 * @param event The key event to execute. 344 * @return Return true if the event was handled, else false. 345 */ 346 public boolean executeKeyEvent(KeyEvent event) { 347 mTempRect.setEmpty(); 348 349 if (!canScroll()) { 350 if (isFocused()) { 351 View currentFocused = findFocus(); 352 if (currentFocused == this) currentFocused = null; 353 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 354 currentFocused, View.FOCUS_RIGHT); 355 return nextFocused != null && nextFocused != this && 356 nextFocused.requestFocus(View.FOCUS_RIGHT); 357 } 358 return false; 359 } 360 361 boolean handled = false; 362 if (event.getAction() == KeyEvent.ACTION_DOWN) { 363 switch (event.getKeyCode()) { 364 case KeyEvent.KEYCODE_DPAD_LEFT: 365 if (!event.isAltPressed()) { 366 handled = arrowScroll(View.FOCUS_LEFT); 367 } else { 368 handled = fullScroll(View.FOCUS_LEFT); 369 } 370 break; 371 case KeyEvent.KEYCODE_DPAD_RIGHT: 372 if (!event.isAltPressed()) { 373 handled = arrowScroll(View.FOCUS_RIGHT); 374 } else { 375 handled = fullScroll(View.FOCUS_RIGHT); 376 } 377 break; 378 case KeyEvent.KEYCODE_SPACE: 379 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 380 break; 381 } 382 } 383 384 return handled; 385 } 386 387 private boolean inChild(int x, int y) { 388 if (getChildCount() > 0) { 389 final int scrollX = mScrollX; 390 final View child = getChildAt(0); 391 return !(y < child.getTop() 392 || y >= child.getBottom() 393 || x < child.getLeft() - scrollX 394 || x >= child.getRight() - scrollX); 395 } 396 return false; 397 } 398 399 @Override 400 public boolean onInterceptTouchEvent(MotionEvent ev) { 401 /* 402 * This method JUST determines whether we want to intercept the motion. 403 * If we return true, onMotionEvent will be called and we do the actual 404 * scrolling there. 405 */ 406 407 /* 408 * Shortcut the most recurring case: the user is in the dragging 409 * state and he is moving his finger. We want to intercept this 410 * motion. 411 */ 412 final int action = ev.getAction(); 413 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 414 return true; 415 } 416 417 switch (action & MotionEvent.ACTION_MASK) { 418 case MotionEvent.ACTION_MOVE: { 419 /* 420 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 421 * whether the user has moved far enough from his original down touch. 422 */ 423 424 /* 425 * Locally do absolute value. mLastMotionX is set to the x value 426 * of the down event. 427 */ 428 final int activePointerId = mActivePointerId; 429 if (activePointerId == INVALID_POINTER) { 430 // If we don't have a valid id, the touch down wasn't on content. 431 break; 432 } 433 434 final int pointerIndex = ev.findPointerIndex(activePointerId); 435 final float x = ev.getX(pointerIndex); 436 final int xDiff = (int) Math.abs(x - mLastMotionX); 437 if (xDiff > mTouchSlop) { 438 mIsBeingDragged = true; 439 mLastMotionX = x; 440 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 441 } 442 break; 443 } 444 445 case MotionEvent.ACTION_DOWN: { 446 final float x = ev.getX(); 447 if (!inChild((int) x, (int) ev.getY())) { 448 mIsBeingDragged = false; 449 break; 450 } 451 452 /* 453 * Remember location of down touch. 454 * ACTION_DOWN always refers to pointer index 0. 455 */ 456 mLastMotionX = x; 457 mActivePointerId = ev.getPointerId(0); 458 459 /* 460 * If being flinged and user touches the screen, initiate drag; 461 * otherwise don't. mScroller.isFinished should be false when 462 * being flinged. 463 */ 464 mIsBeingDragged = !mScroller.isFinished(); 465 break; 466 } 467 468 case MotionEvent.ACTION_CANCEL: 469 case MotionEvent.ACTION_UP: 470 /* Release the drag */ 471 mIsBeingDragged = false; 472 mActivePointerId = INVALID_POINTER; 473 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 474 invalidate(); 475 } 476 break; 477 case MotionEvent.ACTION_POINTER_UP: 478 onSecondaryPointerUp(ev); 479 break; 480 } 481 482 /* 483 * The only time we want to intercept motion events is if we are in the 484 * drag mode. 485 */ 486 return mIsBeingDragged; 487 } 488 489 @Override 490 public boolean onTouchEvent(MotionEvent ev) { 491 492 if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { 493 // Don't handle edge touches immediately -- they may actually belong to one of our 494 // descendants. 495 return false; 496 } 497 498 if (mVelocityTracker == null) { 499 mVelocityTracker = VelocityTracker.obtain(); 500 } 501 mVelocityTracker.addMovement(ev); 502 503 final int action = ev.getAction(); 504 505 switch (action & MotionEvent.ACTION_MASK) { 506 case MotionEvent.ACTION_DOWN: { 507 mIsBeingDragged = getChildCount() != 0; 508 if (!mIsBeingDragged) { 509 return false; 510 } 511 512 /* 513 * If being flinged and user touches, stop the fling. isFinished 514 * will be false if being flinged. 515 */ 516 if (!mScroller.isFinished()) { 517 mScroller.abortAnimation(); 518 } 519 520 // Remember where the motion event started 521 mLastMotionX = ev.getX(); 522 mActivePointerId = ev.getPointerId(0); 523 break; 524 } 525 case MotionEvent.ACTION_MOVE: 526 if (mIsBeingDragged) { 527 // Scroll to follow the motion event 528 final int activePointerIndex = ev.findPointerIndex(mActivePointerId); 529 final float x = ev.getX(activePointerIndex); 530 final int deltaX = (int) (mLastMotionX - x); 531 mLastMotionX = x; 532 533 final int oldX = mScrollX; 534 final int oldY = mScrollY; 535 final int range = getScrollRange(); 536 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 537 mOverscrollDistance, 0, true)) { 538 // Break our velocity if we hit a scroll barrier. 539 mVelocityTracker.clear(); 540 } 541 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 542 543 final int overscrollMode = getOverScrollMode(); 544 if (overscrollMode == OVER_SCROLL_ALWAYS || 545 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { 546 final int pulledToX = oldX + deltaX; 547 if (pulledToX < 0) { 548 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 549 if (!mEdgeGlowRight.isFinished()) { 550 mEdgeGlowRight.onRelease(); 551 } 552 } else if (pulledToX > range) { 553 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 554 if (!mEdgeGlowLeft.isFinished()) { 555 mEdgeGlowLeft.onRelease(); 556 } 557 } 558 if (mEdgeGlowLeft != null 559 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 560 invalidate(); 561 } 562 } 563 } 564 break; 565 case MotionEvent.ACTION_UP: 566 if (mIsBeingDragged) { 567 final VelocityTracker velocityTracker = mVelocityTracker; 568 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 569 int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); 570 571 if (getChildCount() > 0) { 572 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 573 fling(-initialVelocity); 574 } else { 575 final int right = getScrollRange(); 576 if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { 577 invalidate(); 578 } 579 } 580 } 581 582 mActivePointerId = INVALID_POINTER; 583 mIsBeingDragged = false; 584 585 if (mVelocityTracker != null) { 586 mVelocityTracker.recycle(); 587 mVelocityTracker = null; 588 } 589 if (mEdgeGlowLeft != null) { 590 mEdgeGlowLeft.onRelease(); 591 mEdgeGlowRight.onRelease(); 592 } 593 } 594 break; 595 case MotionEvent.ACTION_CANCEL: 596 if (mIsBeingDragged && getChildCount() > 0) { 597 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 598 invalidate(); 599 } 600 mActivePointerId = INVALID_POINTER; 601 mIsBeingDragged = false; 602 if (mVelocityTracker != null) { 603 mVelocityTracker.recycle(); 604 mVelocityTracker = null; 605 } 606 if (mEdgeGlowLeft != null) { 607 mEdgeGlowLeft.onRelease(); 608 mEdgeGlowRight.onRelease(); 609 } 610 } 611 break; 612 case MotionEvent.ACTION_POINTER_UP: 613 onSecondaryPointerUp(ev); 614 break; 615 } 616 return true; 617 } 618 619 private void onSecondaryPointerUp(MotionEvent ev) { 620 final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> 621 MotionEvent.ACTION_POINTER_INDEX_SHIFT; 622 final int pointerId = ev.getPointerId(pointerIndex); 623 if (pointerId == mActivePointerId) { 624 // This was our active pointer going up. Choose a new 625 // active pointer and adjust accordingly. 626 // TODO: Make this decision more intelligent. 627 final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 628 mLastMotionX = ev.getX(newPointerIndex); 629 mActivePointerId = ev.getPointerId(newPointerIndex); 630 if (mVelocityTracker != null) { 631 mVelocityTracker.clear(); 632 } 633 } 634 } 635 636 @Override 637 protected void onOverScrolled(int scrollX, int scrollY, 638 boolean clampedX, boolean clampedY) { 639 // Treat animating scrolls differently; see #computeScroll() for why. 640 if (!mScroller.isFinished()) { 641 mScrollX = scrollX; 642 mScrollY = scrollY; 643 invalidateParentIfNeeded(); 644 if (clampedX) { 645 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 646 } 647 } else { 648 super.scrollTo(scrollX, scrollY); 649 } 650 awakenScrollBars(); 651 } 652 653 private int getScrollRange() { 654 int scrollRange = 0; 655 if (getChildCount() > 0) { 656 View child = getChildAt(0); 657 scrollRange = Math.max(0, 658 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 659 } 660 return scrollRange; 661 } 662 663 /** 664 * <p> 665 * Finds the next focusable component that fits in this View's bounds 666 * (excluding fading edges) pretending that this View's left is located at 667 * the parameter left. 668 * </p> 669 * 670 * @param leftFocus look for a candidate is the one at the left of the bounds 671 * if leftFocus is true, or at the right of the bounds if leftFocus 672 * is false 673 * @param left the left offset of the bounds in which a focusable must be 674 * found (the fading edge is assumed to start at this position) 675 * @param preferredFocusable the View that has highest priority and will be 676 * returned if it is within my bounds (null is valid) 677 * @return the next focusable component in the bounds or null if none can be found 678 */ 679 private View findFocusableViewInMyBounds(final boolean leftFocus, 680 final int left, View preferredFocusable) { 681 /* 682 * The fading edge's transparent side should be considered for focus 683 * since it's mostly visible, so we divide the actual fading edge length 684 * by 2. 685 */ 686 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 687 final int leftWithoutFadingEdge = left + fadingEdgeLength; 688 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 689 690 if ((preferredFocusable != null) 691 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 692 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 693 return preferredFocusable; 694 } 695 696 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 697 rightWithoutFadingEdge); 698 } 699 700 /** 701 * <p> 702 * Finds the next focusable component that fits in the specified bounds. 703 * </p> 704 * 705 * @param leftFocus look for a candidate is the one at the left of the bounds 706 * if leftFocus is true, or at the right of the bounds if 707 * leftFocus is false 708 * @param left the left offset of the bounds in which a focusable must be 709 * found 710 * @param right the right offset of the bounds in which a focusable must 711 * be found 712 * @return the next focusable component in the bounds or null if none can 713 * be found 714 */ 715 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 716 717 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 718 View focusCandidate = null; 719 720 /* 721 * A fully contained focusable is one where its left is below the bound's 722 * left, and its right is above the bound's right. A partially 723 * contained focusable is one where some part of it is within the 724 * bounds, but it also has some part that is not within bounds. A fully contained 725 * focusable is preferred to a partially contained focusable. 726 */ 727 boolean foundFullyContainedFocusable = false; 728 729 int count = focusables.size(); 730 for (int i = 0; i < count; i++) { 731 View view = focusables.get(i); 732 int viewLeft = view.getLeft(); 733 int viewRight = view.getRight(); 734 735 if (left < viewRight && viewLeft < right) { 736 /* 737 * the focusable is in the target area, it is a candidate for 738 * focusing 739 */ 740 741 final boolean viewIsFullyContained = (left < viewLeft) && 742 (viewRight < right); 743 744 if (focusCandidate == null) { 745 /* No candidate, take this one */ 746 focusCandidate = view; 747 foundFullyContainedFocusable = viewIsFullyContained; 748 } else { 749 final boolean viewIsCloserToBoundary = 750 (leftFocus && viewLeft < focusCandidate.getLeft()) || 751 (!leftFocus && viewRight > focusCandidate.getRight()); 752 753 if (foundFullyContainedFocusable) { 754 if (viewIsFullyContained && viewIsCloserToBoundary) { 755 /* 756 * We're dealing with only fully contained views, so 757 * it has to be closer to the boundary to beat our 758 * candidate 759 */ 760 focusCandidate = view; 761 } 762 } else { 763 if (viewIsFullyContained) { 764 /* Any fully contained view beats a partially contained view */ 765 focusCandidate = view; 766 foundFullyContainedFocusable = true; 767 } else if (viewIsCloserToBoundary) { 768 /* 769 * Partially contained view beats another partially 770 * contained view if it's closer 771 */ 772 focusCandidate = view; 773 } 774 } 775 } 776 } 777 } 778 779 return focusCandidate; 780 } 781 782 /** 783 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 784 * method will scroll the view by one page left or right and give the focus 785 * to the leftmost/rightmost component in the new visible area. If no 786 * component is a good candidate for focus, this scrollview reclaims the 787 * focus.</p> 788 * 789 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 790 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 791 * to go one page right 792 * @return true if the key event is consumed by this method, false otherwise 793 */ 794 public boolean pageScroll(int direction) { 795 boolean right = direction == View.FOCUS_RIGHT; 796 int width = getWidth(); 797 798 if (right) { 799 mTempRect.left = getScrollX() + width; 800 int count = getChildCount(); 801 if (count > 0) { 802 View view = getChildAt(0); 803 if (mTempRect.left + width > view.getRight()) { 804 mTempRect.left = view.getRight() - width; 805 } 806 } 807 } else { 808 mTempRect.left = getScrollX() - width; 809 if (mTempRect.left < 0) { 810 mTempRect.left = 0; 811 } 812 } 813 mTempRect.right = mTempRect.left + width; 814 815 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 816 } 817 818 /** 819 * <p>Handles scrolling in response to a "home/end" shortcut press. This 820 * method will scroll the view to the left or right and give the focus 821 * to the leftmost/rightmost component in the new visible area. If no 822 * component is a good candidate for focus, this scrollview reclaims the 823 * focus.</p> 824 * 825 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 826 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 827 * to go the right 828 * @return true if the key event is consumed by this method, false otherwise 829 */ 830 public boolean fullScroll(int direction) { 831 boolean right = direction == View.FOCUS_RIGHT; 832 int width = getWidth(); 833 834 mTempRect.left = 0; 835 mTempRect.right = width; 836 837 if (right) { 838 int count = getChildCount(); 839 if (count > 0) { 840 View view = getChildAt(0); 841 mTempRect.right = view.getRight(); 842 mTempRect.left = mTempRect.right - width; 843 } 844 } 845 846 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 847 } 848 849 /** 850 * <p>Scrolls the view to make the area defined by <code>left</code> and 851 * <code>right</code> visible. This method attempts to give the focus 852 * to a component visible in this area. If no component can be focused in 853 * the new visible area, the focus is reclaimed by this scrollview.</p> 854 * 855 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 856 * to go left {@link android.view.View#FOCUS_RIGHT} to right 857 * @param left the left offset of the new area to be made visible 858 * @param right the right offset of the new area to be made visible 859 * @return true if the key event is consumed by this method, false otherwise 860 */ 861 private boolean scrollAndFocus(int direction, int left, int right) { 862 boolean handled = true; 863 864 int width = getWidth(); 865 int containerLeft = getScrollX(); 866 int containerRight = containerLeft + width; 867 boolean goLeft = direction == View.FOCUS_LEFT; 868 869 View newFocused = findFocusableViewInBounds(goLeft, left, right); 870 if (newFocused == null) { 871 newFocused = this; 872 } 873 874 if (left >= containerLeft && right <= containerRight) { 875 handled = false; 876 } else { 877 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 878 doScrollX(delta); 879 } 880 881 if (newFocused != findFocus()) newFocused.requestFocus(direction); 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 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 1045 protected int computeHorizontalScrollOffset() { 1046 return Math.max(0, super.computeHorizontalScrollOffset()); 1047 } 1048 1049 @Override 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 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 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 */ 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 */ 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 */ 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 1231 public void requestChildFocus(View child, View focused) { 1232 if (!mIsLayoutDirty) { 1233 scrollToChild(focused); 1234 } else { 1235 // The child may not be laid out yet, we can't compute the scroll yet 1236 mChildToScrollTo = focused; 1237 } 1238 super.requestChildFocus(child, focused); 1239 } 1240 1241 1242 /** 1243 * When looking for focus in children of a scroll view, need to be a little 1244 * more careful not to give focus to something that is scrolled off screen. 1245 * 1246 * This is more expensive than the default {@link android.view.ViewGroup} 1247 * implementation, otherwise this behavior might have been made the default. 1248 */ 1249 @Override 1250 protected boolean onRequestFocusInDescendants(int direction, 1251 Rect previouslyFocusedRect) { 1252 1253 // convert from forward / backward notation to up / down / left / right 1254 // (ugh). 1255 if (direction == View.FOCUS_FORWARD) { 1256 direction = View.FOCUS_RIGHT; 1257 } else if (direction == View.FOCUS_BACKWARD) { 1258 direction = View.FOCUS_LEFT; 1259 } 1260 1261 final View nextFocus = previouslyFocusedRect == null ? 1262 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1263 FocusFinder.getInstance().findNextFocusFromRect(this, 1264 previouslyFocusedRect, direction); 1265 1266 if (nextFocus == null) { 1267 return false; 1268 } 1269 1270 if (isOffScreen(nextFocus)) { 1271 return false; 1272 } 1273 1274 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1275 } 1276 1277 @Override 1278 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1279 boolean immediate) { 1280 // offset into coordinate space of this scroll view 1281 rectangle.offset(child.getLeft() - child.getScrollX(), 1282 child.getTop() - child.getScrollY()); 1283 1284 return scrollToChildRect(rectangle, immediate); 1285 } 1286 1287 @Override 1288 public void requestLayout() { 1289 mIsLayoutDirty = true; 1290 super.requestLayout(); 1291 } 1292 1293 @Override 1294 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1295 super.onLayout(changed, l, t, r, b); 1296 mIsLayoutDirty = false; 1297 // Give a child focus if it needs it 1298 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1299 scrollToChild(mChildToScrollTo); 1300 } 1301 mChildToScrollTo = null; 1302 1303 // Calling this with the present values causes it to re-clam them 1304 scrollTo(mScrollX, mScrollY); 1305 } 1306 1307 @Override 1308 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1309 super.onSizeChanged(w, h, oldw, oldh); 1310 1311 View currentFocused = findFocus(); 1312 if (null == currentFocused || this == currentFocused) 1313 return; 1314 1315 final int maxJump = mRight - mLeft; 1316 1317 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1318 currentFocused.getDrawingRect(mTempRect); 1319 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1320 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1321 doScrollX(scrollDelta); 1322 } 1323 } 1324 1325 /** 1326 * Return true if child is an descendant of parent, (or equal to the parent). 1327 */ 1328 private boolean isViewDescendantOf(View child, View parent) { 1329 if (child == parent) { 1330 return true; 1331 } 1332 1333 final ViewParent theParent = child.getParent(); 1334 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1335 } 1336 1337 /** 1338 * Fling the scroll view 1339 * 1340 * @param velocityX The initial velocity in the X direction. Positive 1341 * numbers mean that the finger/curor is moving down the screen, 1342 * which means we want to scroll towards the left. 1343 */ 1344 public void fling(int velocityX) { 1345 if (getChildCount() > 0) { 1346 int width = getWidth() - mPaddingRight - mPaddingLeft; 1347 int right = getChildAt(0).getWidth(); 1348 1349 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1350 Math.max(0, right - width), 0, 0, width/2, 0); 1351 1352 final boolean movingRight = velocityX > 0; 1353 1354 View currentFocused = findFocus(); 1355 View newFocused = findFocusableViewInMyBounds(movingRight, 1356 mScroller.getFinalX(), currentFocused); 1357 1358 if (newFocused == null) { 1359 newFocused = this; 1360 } 1361 1362 if (newFocused != currentFocused) { 1363 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1364 } 1365 1366 invalidate(); 1367 } 1368 } 1369 1370 /** 1371 * {@inheritDoc} 1372 * 1373 * <p>This version also clamps the scrolling to the bounds of our child. 1374 */ 1375 @Override 1376 public void scrollTo(int x, int y) { 1377 // we rely on the fact the View.scrollBy calls scrollTo. 1378 if (getChildCount() > 0) { 1379 View child = getChildAt(0); 1380 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1381 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1382 if (x != mScrollX || y != mScrollY) { 1383 super.scrollTo(x, y); 1384 } 1385 } 1386 } 1387 1388 @Override 1389 public void setOverScrollMode(int mode) { 1390 if (mode != OVER_SCROLL_NEVER) { 1391 if (mEdgeGlowLeft == null) { 1392 Context context = getContext(); 1393 final Resources res = context.getResources(); 1394 final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); 1395 final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); 1396 mEdgeGlowLeft = new EdgeGlow(context, edge, glow); 1397 mEdgeGlowRight = new EdgeGlow(context, edge, glow); 1398 } 1399 } else { 1400 mEdgeGlowLeft = null; 1401 mEdgeGlowRight = null; 1402 } 1403 super.setOverScrollMode(mode); 1404 } 1405 1406 @Override 1407 public void draw(Canvas canvas) { 1408 super.draw(canvas); 1409 if (mEdgeGlowLeft != null) { 1410 final int scrollX = mScrollX; 1411 if (!mEdgeGlowLeft.isFinished()) { 1412 final int restoreCount = canvas.save(); 1413 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1414 1415 canvas.rotate(270); 1416 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1417 mEdgeGlowLeft.setSize(height, getWidth()); 1418 if (mEdgeGlowLeft.draw(canvas)) { 1419 invalidate(); 1420 } 1421 canvas.restoreToCount(restoreCount); 1422 } 1423 if (!mEdgeGlowRight.isFinished()) { 1424 final int restoreCount = canvas.save(); 1425 final int width = getWidth(); 1426 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1427 1428 canvas.rotate(90); 1429 canvas.translate(-mPaddingTop, 1430 -(Math.max(getScrollRange(), scrollX) + width)); 1431 mEdgeGlowRight.setSize(height, width); 1432 if (mEdgeGlowRight.draw(canvas)) { 1433 invalidate(); 1434 } 1435 canvas.restoreToCount(restoreCount); 1436 } 1437 } 1438 } 1439 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