1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.videoeditor.widgets; 18 19 import android.content.Context; 20 import android.content.res.TypedArray; 21 import android.graphics.Canvas; 22 import android.graphics.Rect; 23 import android.os.Bundle; 24 import android.util.AttributeSet; 25 import android.view.FocusFinder; 26 import android.view.InputDevice; 27 import android.view.KeyEvent; 28 import android.view.MotionEvent; 29 import android.view.VelocityTracker; 30 import android.view.View; 31 import android.view.ViewConfiguration; 32 import android.view.ViewDebug; 33 import android.view.ViewGroup; 34 import android.view.ViewParent; 35 import android.view.accessibility.AccessibilityEvent; 36 import android.view.accessibility.AccessibilityNodeInfo; 37 import android.view.animation.AnimationUtils; 38 import android.widget.EdgeEffect; 39 import android.widget.FrameLayout; 40 import android.widget.OverScroller; 41 42 import java.util.List; 43 44 /** 45 * Layout container for a view hierarchy that can be scrolled by the user, 46 * allowing it to be larger than the physical display. A HorizontalScrollView 47 * is a {@link FrameLayout}, meaning you should place one child in it 48 * containing the entire contents to scroll; this child may itself be a layout 49 * manager with a complex hierarchy of objects. A child that is often used 50 * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal 51 * array of top-level items that the user can scroll through. 52 * 53 * <p>The {@link TextView} class also 54 * takes care of its own scrolling, so does not require a HorizontalScrollView, but 55 * using the two together is possible to achieve the effect of a text view 56 * within a larger container. 57 * 58 * <p>HorizontalScrollView only supports horizontal scrolling. For vertical scrolling, 59 * use either {@link ScrollView} or {@link ListView}. 60 * 61 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 62 */ 63 public class HorizontalScrollView extends FrameLayout { 64 private static final int ANIMATED_SCROLL_GAP = 250; 65 66 private static final float MAX_SCROLL_FACTOR = 0.5f; 67 68 69 private long mLastScroll; 70 71 private final Rect mTempRect = new Rect(); 72 private OverScroller mScroller; 73 private EdgeEffect mEdgeGlowLeft; 74 private EdgeEffect mEdgeGlowRight; 75 76 /** 77 * X position of the last focal point. 78 */ 79 private int mLastFocusX; 80 81 /** 82 * True if the value of mLastFocusX is still valid. 83 */ 84 private boolean mHasLastFocusX; 85 86 /** 87 * True when the layout has changed but the traversal has not come through yet. 88 * Ideally the view hierarchy would keep track of this for us. 89 */ 90 private boolean mIsLayoutDirty = true; 91 92 /** 93 * The child to give focus to in the event that a child has requested focus while the 94 * layout is dirty. This prevents the scroll from being wrong if the child has not been 95 * laid out before requesting focus. 96 */ 97 private View mChildToScrollTo = null; 98 99 /** 100 * True if the user is currently dragging this ScrollView around. This is 101 * not the same as 'is being flinged', which can be checked by 102 * mScroller.isFinished() (flinging begins when the user lifts his finger). 103 */ 104 private boolean mIsBeingDragged = false; 105 106 /** 107 * Determines speed during touch scrolling 108 */ 109 private VelocityTracker mVelocityTracker; 110 111 /** 112 * When set to true, the scroll view measure its child to make it fill the currently 113 * visible area. 114 */ 115 @ViewDebug.ExportedProperty(category = "layout") 116 private boolean mFillViewport; 117 118 /** 119 * Whether arrow scrolling is animated. 120 */ 121 private boolean mSmoothScrollingEnabled = true; 122 123 private int mTouchSlop; 124 private int mMinimumVelocity; 125 private int mMaximumVelocity; 126 127 private int mOverscrollDistance; 128 private int mOverflingDistance; 129 130 public HorizontalScrollView(Context context) { 131 this(context, null); 132 } 133 134 public HorizontalScrollView(Context context, AttributeSet attrs) { 135 this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); 136 } 137 138 public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { 139 super(context, attrs, defStyle); 140 initScrollView(); 141 142 TypedArray a = context.obtainStyledAttributes(attrs, 143 android.R.styleable.HorizontalScrollView, defStyle, 0); 144 145 setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); 146 147 a.recycle(); 148 } 149 150 @Override 151 protected float getLeftFadingEdgeStrength() { 152 if (getChildCount() == 0) { 153 return 0.0f; 154 } 155 156 final int length = getHorizontalFadingEdgeLength(); 157 if (mScrollX < length) { 158 return mScrollX / (float) length; 159 } 160 161 return 1.0f; 162 } 163 164 @Override 165 protected float getRightFadingEdgeStrength() { 166 if (getChildCount() == 0) { 167 return 0.0f; 168 } 169 170 final int length = getHorizontalFadingEdgeLength(); 171 final int rightEdge = getWidth() - mPaddingRight; 172 final int span = getChildAt(0).getRight() - mScrollX - rightEdge; 173 if (span < length) { 174 return span / (float) length; 175 } 176 177 return 1.0f; 178 } 179 180 /** 181 * @return The maximum amount this scroll view will scroll in response to 182 * an arrow event. 183 */ 184 public int getMaxScrollAmount() { 185 return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); 186 } 187 188 189 private void initScrollView() { 190 mScroller = new OverScroller(getContext()); 191 setFocusable(true); 192 setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); 193 setWillNotDraw(false); 194 final ViewConfiguration configuration = ViewConfiguration.get(mContext); 195 mTouchSlop = configuration.getScaledTouchSlop(); 196 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 197 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); 198 mOverscrollDistance = configuration.getScaledOverscrollDistance(); 199 mOverflingDistance = configuration.getScaledOverflingDistance(); 200 } 201 202 @Override 203 public void addView(View child) { 204 if (getChildCount() > 0) { 205 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 206 } 207 208 super.addView(child); 209 } 210 211 @Override 212 public void addView(View child, int index) { 213 if (getChildCount() > 0) { 214 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 215 } 216 217 super.addView(child, index); 218 } 219 220 @Override 221 public void addView(View child, ViewGroup.LayoutParams params) { 222 if (getChildCount() > 0) { 223 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 224 } 225 226 super.addView(child, params); 227 } 228 229 @Override 230 public void addView(View child, int index, ViewGroup.LayoutParams params) { 231 if (getChildCount() > 0) { 232 throw new IllegalStateException("HorizontalScrollView can host only one direct child"); 233 } 234 235 super.addView(child, index, params); 236 } 237 238 /** 239 * @return Returns true this HorizontalScrollView can be scrolled 240 */ 241 private boolean canScroll() { 242 View child = getChildAt(0); 243 if (child != null) { 244 int childWidth = child.getWidth(); 245 return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; 246 } 247 return false; 248 } 249 250 /** 251 * Indicates whether this HorizontalScrollView's content is stretched to 252 * fill the viewport. 253 * 254 * @return True if the content fills the viewport, false otherwise. 255 * 256 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 257 */ 258 public boolean isFillViewport() { 259 return mFillViewport; 260 } 261 262 /** 263 * Indicates this HorizontalScrollView whether it should stretch its content width 264 * to fill the viewport or not. 265 * 266 * @param fillViewport True to stretch the content's width to the viewport's 267 * boundaries, false otherwise. 268 * 269 * @attr ref android.R.styleable#HorizontalScrollView_fillViewport 270 */ 271 public void setFillViewport(boolean fillViewport) { 272 if (fillViewport != mFillViewport) { 273 mFillViewport = fillViewport; 274 requestLayout(); 275 } 276 } 277 278 /** 279 * @return Whether arrow scrolling will animate its transition. 280 */ 281 public boolean isSmoothScrollingEnabled() { 282 return mSmoothScrollingEnabled; 283 } 284 285 /** 286 * Set whether arrow scrolling will animate its transition. 287 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 288 */ 289 public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { 290 mSmoothScrollingEnabled = smoothScrollingEnabled; 291 } 292 293 @Override 294 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 295 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 296 297 if (!mFillViewport) { 298 return; 299 } 300 301 final int widthMode = MeasureSpec.getMode(widthMeasureSpec); 302 if (widthMode == MeasureSpec.UNSPECIFIED) { 303 return; 304 } 305 306 if (getChildCount() > 0) { 307 final View child = getChildAt(0); 308 int width = getMeasuredWidth(); 309 if (child.getMeasuredWidth() < width) { 310 final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); 311 312 int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop 313 + mPaddingBottom, lp.height); 314 width -= mPaddingLeft; 315 width -= mPaddingRight; 316 int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); 317 318 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 319 } 320 } 321 } 322 323 @Override 324 public boolean dispatchKeyEvent(KeyEvent event) { 325 // Let the focused view and/or our descendants get the key first 326 return super.dispatchKeyEvent(event) || executeKeyEvent(event); 327 } 328 329 /** 330 * You can call this function yourself to have the scroll view perform 331 * scrolling from a key event, just as if the event had been dispatched to 332 * it by the view hierarchy. 333 * 334 * @param event The key event to execute. 335 * @return Return true if the event was handled, else false. 336 */ 337 public boolean executeKeyEvent(KeyEvent event) { 338 mTempRect.setEmpty(); 339 340 if (!canScroll()) { 341 if (isFocused()) { 342 View currentFocused = findFocus(); 343 if (currentFocused == this) currentFocused = null; 344 View nextFocused = FocusFinder.getInstance().findNextFocus(this, 345 currentFocused, View.FOCUS_RIGHT); 346 return nextFocused != null && nextFocused != this && 347 nextFocused.requestFocus(View.FOCUS_RIGHT); 348 } 349 return false; 350 } 351 352 boolean handled = false; 353 if (event.getAction() == KeyEvent.ACTION_DOWN) { 354 switch (event.getKeyCode()) { 355 case KeyEvent.KEYCODE_DPAD_LEFT: 356 if (!event.isAltPressed()) { 357 handled = arrowScroll(View.FOCUS_LEFT); 358 } else { 359 handled = fullScroll(View.FOCUS_LEFT); 360 } 361 break; 362 case KeyEvent.KEYCODE_DPAD_RIGHT: 363 if (!event.isAltPressed()) { 364 handled = arrowScroll(View.FOCUS_RIGHT); 365 } else { 366 handled = fullScroll(View.FOCUS_RIGHT); 367 } 368 break; 369 case KeyEvent.KEYCODE_SPACE: 370 pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); 371 break; 372 } 373 } 374 375 return handled; 376 } 377 378 private boolean inChild(int x, int y) { 379 if (getChildCount() > 0) { 380 final int scrollX = mScrollX; 381 final View child = getChildAt(0); 382 return !(y < child.getTop() 383 || y >= child.getBottom() 384 || x < child.getLeft() - scrollX 385 || x >= child.getRight() - scrollX); 386 } 387 return false; 388 } 389 390 private void initOrResetVelocityTracker() { 391 if (mVelocityTracker == null) { 392 mVelocityTracker = VelocityTracker.obtain(); 393 } else { 394 mVelocityTracker.clear(); 395 } 396 } 397 398 private void initVelocityTrackerIfNotExists() { 399 if (mVelocityTracker == null) { 400 mVelocityTracker = VelocityTracker.obtain(); 401 } 402 } 403 404 private void recycleVelocityTracker() { 405 if (mVelocityTracker != null) { 406 mVelocityTracker.recycle(); 407 mVelocityTracker = null; 408 } 409 } 410 411 private static int getFocusX(MotionEvent ev) { 412 final int action = ev.getAction(); 413 final boolean pointerUp = 414 (action & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_POINTER_UP; 415 final int skipIndex = pointerUp ? ev.getActionIndex() : -1; 416 417 // Determine focal point 418 float sumX = 0; 419 final int count = ev.getPointerCount(); 420 for (int i = 0; i < count; i++) { 421 if (skipIndex == i) continue; 422 sumX += ev.getX(i); 423 } 424 final int div = pointerUp ? count - 1 : count; 425 final float focusX = sumX / div; 426 return (int) focusX; 427 } 428 429 @Override 430 public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { 431 if (disallowIntercept) { 432 recycleVelocityTracker(); 433 } 434 super.requestDisallowInterceptTouchEvent(disallowIntercept); 435 } 436 437 @Override 438 public boolean onInterceptTouchEvent(MotionEvent ev) { 439 /* 440 * This method JUST determines whether we want to intercept the motion. 441 * If we return true, onMotionEvent will be called and we do the actual 442 * scrolling there. 443 */ 444 445 /* 446 * Shortcut the most recurring case: the user is in the dragging 447 * state and he is moving his finger. We want to intercept this 448 * motion. 449 */ 450 final int action = ev.getAction(); 451 if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { 452 return true; 453 } 454 455 switch (action & MotionEvent.ACTION_MASK) { 456 case MotionEvent.ACTION_MOVE: { 457 /* 458 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 459 * whether the user has moved far enough from his original down touch. 460 */ 461 462 if (!mHasLastFocusX) { 463 // If we don't have a valid mLastFocusX, the touch down wasn't 464 // on content. 465 break; 466 } 467 468 final int x = getFocusX(ev); 469 final int xDiff = (int) Math.abs(x - mLastFocusX); 470 if (xDiff > mTouchSlop) { 471 mIsBeingDragged = true; 472 mLastFocusX = x; 473 initVelocityTrackerIfNotExists(); 474 mVelocityTracker.addMovement(ev); 475 if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); 476 } 477 break; 478 } 479 480 case MotionEvent.ACTION_DOWN: { 481 final int x = (int) ev.getX(); 482 if (!inChild((int) x, (int) ev.getY())) { 483 mIsBeingDragged = false; 484 recycleVelocityTracker(); 485 break; 486 } 487 488 /* 489 * Remember location of down touch. 490 */ 491 mLastFocusX = getFocusX(ev); 492 mHasLastFocusX = true; 493 494 initOrResetVelocityTracker(); 495 mVelocityTracker.addMovement(ev); 496 497 /* 498 * If being flinged and user touches the screen, initiate drag; 499 * otherwise don't. mScroller.isFinished should be false when 500 * being flinged. 501 */ 502 mIsBeingDragged = !mScroller.isFinished(); 503 break; 504 } 505 506 case MotionEvent.ACTION_CANCEL: 507 case MotionEvent.ACTION_UP: 508 /* Release the drag */ 509 mIsBeingDragged = false; 510 mHasLastFocusX = false; 511 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 512 postInvalidateOnAnimation(); 513 } 514 break; 515 case MotionEvent.ACTION_POINTER_DOWN: { 516 mLastFocusX = getFocusX(ev); 517 mHasLastFocusX = true; 518 break; 519 } 520 case MotionEvent.ACTION_POINTER_UP: 521 onSecondaryPointerUp(ev); 522 mLastFocusX = getFocusX(ev); 523 break; 524 } 525 526 /* 527 * The only time we want to intercept motion events is if we are in the 528 * drag mode. 529 */ 530 return mIsBeingDragged; 531 } 532 533 @Override 534 public boolean onTouchEvent(MotionEvent ev) { 535 initVelocityTrackerIfNotExists(); 536 mVelocityTracker.addMovement(ev); 537 538 final int action = ev.getAction(); 539 540 switch (action & MotionEvent.ACTION_MASK) { 541 case MotionEvent.ACTION_DOWN: { 542 if (getChildCount() == 0) { 543 return false; 544 } 545 if ((mIsBeingDragged = !mScroller.isFinished())) { 546 final ViewParent parent = getParent(); 547 if (parent != null) { 548 parent.requestDisallowInterceptTouchEvent(true); 549 } 550 } 551 552 /* 553 * If being flinged and user touches, stop the fling. isFinished 554 * will be false if being flinged. 555 */ 556 if (!mScroller.isFinished()) { 557 mScroller.abortAnimation(); 558 } 559 560 // Remember where the motion event started 561 mLastFocusX = getFocusX(ev); 562 mHasLastFocusX = true; 563 break; 564 } 565 case MotionEvent.ACTION_MOVE: 566 final int x = getFocusX(ev); 567 int deltaX = mLastFocusX - x; 568 if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) { 569 final ViewParent parent = getParent(); 570 if (parent != null) { 571 parent.requestDisallowInterceptTouchEvent(true); 572 } 573 mIsBeingDragged = true; 574 if (deltaX > 0) { 575 deltaX -= mTouchSlop; 576 } else { 577 deltaX += mTouchSlop; 578 } 579 } 580 if (mIsBeingDragged) { 581 // Scroll to follow the motion event 582 mLastFocusX = x; 583 584 final int oldX = mScrollX; 585 final int oldY = mScrollY; 586 final int range = getScrollRange(); 587 final int overscrollMode = getOverScrollMode(); 588 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 589 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 590 591 if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, 592 mOverscrollDistance, 0, true)) { 593 // Break our velocity if we hit a scroll barrier. 594 mVelocityTracker.clear(); 595 } 596 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 597 598 if (canOverscroll) { 599 final int pulledToX = oldX + deltaX; 600 if (pulledToX < 0) { 601 mEdgeGlowLeft.onPull((float) deltaX / getWidth()); 602 if (!mEdgeGlowRight.isFinished()) { 603 mEdgeGlowRight.onRelease(); 604 } 605 } else if (pulledToX > range) { 606 mEdgeGlowRight.onPull((float) deltaX / getWidth()); 607 if (!mEdgeGlowLeft.isFinished()) { 608 mEdgeGlowLeft.onRelease(); 609 } 610 } 611 if (mEdgeGlowLeft != null 612 && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { 613 postInvalidateOnAnimation(); 614 } 615 } 616 } 617 break; 618 case MotionEvent.ACTION_UP: 619 if (mIsBeingDragged) { 620 final VelocityTracker velocityTracker = mVelocityTracker; 621 final int pointerId = ev.getPointerId(0); 622 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); 623 int initialVelocity = (int) velocityTracker.getXVelocity(pointerId); 624 625 if (getChildCount() > 0) { 626 if ((Math.abs(initialVelocity) > mMinimumVelocity)) { 627 fling(-initialVelocity); 628 } else { 629 if (mScroller.springBack(mScrollX, mScrollY, 0, 630 getScrollRange(), 0, 0)) { 631 postInvalidateOnAnimation(); 632 } 633 } 634 } 635 636 mHasLastFocusX = false; 637 mIsBeingDragged = false; 638 recycleVelocityTracker(); 639 640 if (mEdgeGlowLeft != null) { 641 mEdgeGlowLeft.onRelease(); 642 mEdgeGlowRight.onRelease(); 643 } 644 } 645 break; 646 case MotionEvent.ACTION_CANCEL: 647 if (mIsBeingDragged && getChildCount() > 0) { 648 if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { 649 postInvalidateOnAnimation(); 650 } 651 mHasLastFocusX = false; 652 mIsBeingDragged = false; 653 recycleVelocityTracker(); 654 655 if (mEdgeGlowLeft != null) { 656 mEdgeGlowLeft.onRelease(); 657 mEdgeGlowRight.onRelease(); 658 } 659 } 660 break; 661 case MotionEvent.ACTION_POINTER_UP: 662 onSecondaryPointerUp(ev); 663 break; 664 } 665 return true; 666 } 667 668 private void onSecondaryPointerUp(MotionEvent ev) { 669 mLastFocusX = getFocusX(ev); 670 mHasLastFocusX = true; 671 if (mVelocityTracker != null) { 672 mVelocityTracker.clear(); 673 } 674 } 675 676 @Override 677 public boolean onGenericMotionEvent(MotionEvent event) { 678 if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { 679 switch (event.getAction()) { 680 case MotionEvent.ACTION_SCROLL: { 681 if (!mIsBeingDragged) { 682 final float hscroll; 683 if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { 684 hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); 685 } else { 686 hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL); 687 } 688 if (hscroll != 0) { 689 final int delta = (int) (hscroll * getHorizontalScrollFactor()); 690 final int range = getScrollRange(); 691 int oldScrollX = mScrollX; 692 int newScrollX = oldScrollX + delta; 693 if (newScrollX < 0) { 694 newScrollX = 0; 695 } else if (newScrollX > range) { 696 newScrollX = range; 697 } 698 if (newScrollX != oldScrollX) { 699 super.scrollTo(newScrollX, mScrollY); 700 return true; 701 } 702 } 703 } 704 } 705 } 706 } 707 return super.onGenericMotionEvent(event); 708 } 709 710 @Override 711 public boolean shouldDelayChildPressedState() { 712 return true; 713 } 714 715 @Override 716 protected void onOverScrolled(int scrollX, int scrollY, 717 boolean clampedX, boolean clampedY) { 718 // Treat animating scrolls differently; see #computeScroll() for why. 719 if (!mScroller.isFinished()) { 720 mScrollX = scrollX; 721 mScrollY = scrollY; 722 invalidateParentIfNeeded(); 723 if (clampedX) { 724 mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); 725 } 726 } else { 727 super.scrollTo(scrollX, scrollY); 728 } 729 730 awakenScrollBars(); 731 } 732 733 @Override 734 public boolean performAccessibilityAction(int action, Bundle arguments) { 735 if (super.performAccessibilityAction(action, arguments)) { 736 return true; 737 } 738 switch (action) { 739 case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: { 740 if (!isEnabled()) { 741 return false; 742 } 743 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 744 final int targetScrollX = Math.min(mScrollX + viewportWidth, getScrollRange()); 745 if (targetScrollX != mScrollX) { 746 smoothScrollTo(targetScrollX, 0); 747 return true; 748 } 749 } return false; 750 case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: { 751 if (!isEnabled()) { 752 return false; 753 } 754 final int viewportWidth = getWidth() - mPaddingLeft - mPaddingRight; 755 final int targetScrollX = Math.max(0, mScrollX - viewportWidth); 756 if (targetScrollX != mScrollX) { 757 smoothScrollTo(targetScrollX, 0); 758 return true; 759 } 760 } return false; 761 } 762 return false; 763 } 764 765 @Override 766 public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { 767 super.onInitializeAccessibilityNodeInfo(info); 768 info.setClassName(HorizontalScrollView.class.getName()); 769 final int scrollRange = getScrollRange(); 770 if (scrollRange > 0) { 771 info.setScrollable(true); 772 if (isEnabled() && mScrollX > 0) { 773 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD); 774 } 775 if (isEnabled() && mScrollX < scrollRange) { 776 info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD); 777 } 778 } 779 } 780 781 @Override 782 public void onInitializeAccessibilityEvent(AccessibilityEvent event) { 783 super.onInitializeAccessibilityEvent(event); 784 event.setClassName(HorizontalScrollView.class.getName()); 785 event.setScrollable(getScrollRange() > 0); 786 event.setScrollX(mScrollX); 787 event.setScrollY(mScrollY); 788 event.setMaxScrollX(getScrollRange()); 789 event.setMaxScrollY(mScrollY); 790 } 791 792 private int getScrollRange() { 793 int scrollRange = 0; 794 if (getChildCount() > 0) { 795 View child = getChildAt(0); 796 scrollRange = Math.max(0, 797 child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); 798 } 799 return scrollRange; 800 } 801 802 /** 803 * <p> 804 * Finds the next focusable component that fits in this View's bounds 805 * (excluding fading edges) pretending that this View's left is located at 806 * the parameter left. 807 * </p> 808 * 809 * @param leftFocus look for a candidate is the one at the left of the bounds 810 * if leftFocus is true, or at the right of the bounds if leftFocus 811 * is false 812 * @param left the left offset of the bounds in which a focusable must be 813 * found (the fading edge is assumed to start at this position) 814 * @param preferredFocusable the View that has highest priority and will be 815 * returned if it is within my bounds (null is valid) 816 * @return the next focusable component in the bounds or null if none can be found 817 */ 818 private View findFocusableViewInMyBounds(final boolean leftFocus, 819 final int left, View preferredFocusable) { 820 /* 821 * The fading edge's transparent side should be considered for focus 822 * since it's mostly visible, so we divide the actual fading edge length 823 * by 2. 824 */ 825 final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; 826 final int leftWithoutFadingEdge = left + fadingEdgeLength; 827 final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; 828 829 if ((preferredFocusable != null) 830 && (preferredFocusable.getLeft() < rightWithoutFadingEdge) 831 && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { 832 return preferredFocusable; 833 } 834 835 return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, 836 rightWithoutFadingEdge); 837 } 838 839 /** 840 * <p> 841 * Finds the next focusable component that fits in the specified bounds. 842 * </p> 843 * 844 * @param leftFocus look for a candidate is the one at the left of the bounds 845 * if leftFocus is true, or at the right of the bounds if 846 * leftFocus is false 847 * @param left the left offset of the bounds in which a focusable must be 848 * found 849 * @param right the right offset of the bounds in which a focusable must 850 * be found 851 * @return the next focusable component in the bounds or null if none can 852 * be found 853 */ 854 private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { 855 856 List<View> focusables = getFocusables(View.FOCUS_FORWARD); 857 View focusCandidate = null; 858 859 /* 860 * A fully contained focusable is one where its left is below the bound's 861 * left, and its right is above the bound's right. A partially 862 * contained focusable is one where some part of it is within the 863 * bounds, but it also has some part that is not within bounds. A fully contained 864 * focusable is preferred to a partially contained focusable. 865 */ 866 boolean foundFullyContainedFocusable = false; 867 868 int count = focusables.size(); 869 for (int i = 0; i < count; i++) { 870 View view = focusables.get(i); 871 int viewLeft = view.getLeft(); 872 int viewRight = view.getRight(); 873 874 if (left < viewRight && viewLeft < right) { 875 /* 876 * the focusable is in the target area, it is a candidate for 877 * focusing 878 */ 879 880 final boolean viewIsFullyContained = (left < viewLeft) && 881 (viewRight < right); 882 883 if (focusCandidate == null) { 884 /* No candidate, take this one */ 885 focusCandidate = view; 886 foundFullyContainedFocusable = viewIsFullyContained; 887 } else { 888 final boolean viewIsCloserToBoundary = 889 (leftFocus && viewLeft < focusCandidate.getLeft()) || 890 (!leftFocus && viewRight > focusCandidate.getRight()); 891 892 if (foundFullyContainedFocusable) { 893 if (viewIsFullyContained && viewIsCloserToBoundary) { 894 /* 895 * We're dealing with only fully contained views, so 896 * it has to be closer to the boundary to beat our 897 * candidate 898 */ 899 focusCandidate = view; 900 } 901 } else { 902 if (viewIsFullyContained) { 903 /* Any fully contained view beats a partially contained view */ 904 focusCandidate = view; 905 foundFullyContainedFocusable = true; 906 } else if (viewIsCloserToBoundary) { 907 /* 908 * Partially contained view beats another partially 909 * contained view if it's closer 910 */ 911 focusCandidate = view; 912 } 913 } 914 } 915 } 916 } 917 918 return focusCandidate; 919 } 920 921 /** 922 * <p>Handles scrolling in response to a "page up/down" shortcut press. This 923 * method will scroll the view by one page left or right and give the focus 924 * to the leftmost/rightmost component in the new visible area. If no 925 * component is a good candidate for focus, this scrollview reclaims the 926 * focus.</p> 927 * 928 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 929 * to go one page left or {@link android.view.View#FOCUS_RIGHT} 930 * to go one page right 931 * @return true if the key event is consumed by this method, false otherwise 932 */ 933 public boolean pageScroll(int direction) { 934 boolean right = direction == View.FOCUS_RIGHT; 935 int width = getWidth(); 936 937 if (right) { 938 mTempRect.left = getScrollX() + width; 939 int count = getChildCount(); 940 if (count > 0) { 941 View view = getChildAt(0); 942 if (mTempRect.left + width > view.getRight()) { 943 mTempRect.left = view.getRight() - width; 944 } 945 } 946 } else { 947 mTempRect.left = getScrollX() - width; 948 if (mTempRect.left < 0) { 949 mTempRect.left = 0; 950 } 951 } 952 mTempRect.right = mTempRect.left + width; 953 954 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 955 } 956 957 /** 958 * <p>Handles scrolling in response to a "home/end" shortcut press. This 959 * method will scroll the view to the left or right and give the focus 960 * to the leftmost/rightmost component in the new visible area. If no 961 * component is a good candidate for focus, this scrollview reclaims the 962 * focus.</p> 963 * 964 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 965 * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} 966 * to go the right 967 * @return true if the key event is consumed by this method, false otherwise 968 */ 969 public boolean fullScroll(int direction) { 970 boolean right = direction == View.FOCUS_RIGHT; 971 int width = getWidth(); 972 973 mTempRect.left = 0; 974 mTempRect.right = width; 975 976 if (right) { 977 int count = getChildCount(); 978 if (count > 0) { 979 View view = getChildAt(0); 980 mTempRect.right = view.getRight(); 981 mTempRect.left = mTempRect.right - width; 982 } 983 } 984 985 return scrollAndFocus(direction, mTempRect.left, mTempRect.right); 986 } 987 988 /** 989 * <p>Scrolls the view to make the area defined by <code>left</code> and 990 * <code>right</code> visible. This method attempts to give the focus 991 * to a component visible in this area. If no component can be focused in 992 * the new visible area, the focus is reclaimed by this scrollview.</p> 993 * 994 * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} 995 * to go left {@link android.view.View#FOCUS_RIGHT} to right 996 * @param left the left offset of the new area to be made visible 997 * @param right the right offset of the new area to be made visible 998 * @return true if the key event is consumed by this method, false otherwise 999 */ 1000 private boolean scrollAndFocus(int direction, int left, int right) { 1001 boolean handled = true; 1002 1003 int width = getWidth(); 1004 int containerLeft = getScrollX(); 1005 int containerRight = containerLeft + width; 1006 boolean goLeft = direction == View.FOCUS_LEFT; 1007 1008 View newFocused = findFocusableViewInBounds(goLeft, left, right); 1009 if (newFocused == null) { 1010 newFocused = this; 1011 } 1012 1013 if (left >= containerLeft && right <= containerRight) { 1014 handled = false; 1015 } else { 1016 int delta = goLeft ? (left - containerLeft) : (right - containerRight); 1017 doScrollX(delta); 1018 } 1019 1020 if (newFocused != findFocus()) newFocused.requestFocus(direction); 1021 1022 return handled; 1023 } 1024 1025 /** 1026 * Handle scrolling in response to a left or right arrow click. 1027 * 1028 * @param direction The direction corresponding to the arrow key that was 1029 * pressed 1030 * @return True if we consumed the event, false otherwise 1031 */ 1032 public boolean arrowScroll(int direction) { 1033 1034 View currentFocused = findFocus(); 1035 if (currentFocused == this) currentFocused = null; 1036 1037 View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); 1038 1039 final int maxJump = getMaxScrollAmount(); 1040 1041 if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { 1042 nextFocused.getDrawingRect(mTempRect); 1043 offsetDescendantRectToMyCoords(nextFocused, mTempRect); 1044 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1045 doScrollX(scrollDelta); 1046 nextFocused.requestFocus(direction); 1047 } else { 1048 // no new focus 1049 int scrollDelta = maxJump; 1050 1051 if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { 1052 scrollDelta = getScrollX(); 1053 } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { 1054 1055 int daRight = getChildAt(0).getRight(); 1056 1057 int screenRight = getScrollX() + getWidth(); 1058 1059 if (daRight - screenRight < maxJump) { 1060 scrollDelta = daRight - screenRight; 1061 } 1062 } 1063 if (scrollDelta == 0) { 1064 return false; 1065 } 1066 doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); 1067 } 1068 1069 if (currentFocused != null && currentFocused.isFocused() 1070 && isOffScreen(currentFocused)) { 1071 // previously focused item still has focus and is off screen, give 1072 // it up (take it back to ourselves) 1073 // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are 1074 // sure to 1075 // get it) 1076 final int descendantFocusability = getDescendantFocusability(); // save 1077 setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); 1078 requestFocus(); 1079 setDescendantFocusability(descendantFocusability); // restore 1080 } 1081 return true; 1082 } 1083 1084 /** 1085 * @return whether the descendant of this scroll view is scrolled off 1086 * screen. 1087 */ 1088 private boolean isOffScreen(View descendant) { 1089 return !isWithinDeltaOfScreen(descendant, 0); 1090 } 1091 1092 /** 1093 * @return whether the descendant of this scroll view is within delta 1094 * pixels of being on the screen. 1095 */ 1096 private boolean isWithinDeltaOfScreen(View descendant, int delta) { 1097 descendant.getDrawingRect(mTempRect); 1098 offsetDescendantRectToMyCoords(descendant, mTempRect); 1099 1100 return (mTempRect.right + delta) >= getScrollX() 1101 && (mTempRect.left - delta) <= (getScrollX() + getWidth()); 1102 } 1103 1104 /** 1105 * Smooth scroll by a X delta 1106 * 1107 * @param delta the number of pixels to scroll by on the X axis 1108 */ 1109 private void doScrollX(int delta) { 1110 if (delta != 0) { 1111 if (mSmoothScrollingEnabled) { 1112 smoothScrollBy(delta, 0); 1113 } else { 1114 scrollBy(delta, 0); 1115 } 1116 } 1117 } 1118 1119 /** 1120 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 1121 * 1122 * @param dx the number of pixels to scroll by on the X axis 1123 * @param dy the number of pixels to scroll by on the Y axis 1124 */ 1125 public final void smoothScrollBy(int dx, int dy) { 1126 if (getChildCount() == 0) { 1127 // Nothing to do. 1128 return; 1129 } 1130 long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; 1131 if (duration > ANIMATED_SCROLL_GAP) { 1132 final int width = getWidth() - mPaddingRight - mPaddingLeft; 1133 final int right = getChildAt(0).getWidth(); 1134 final int maxX = Math.max(0, right - width); 1135 final int scrollX = mScrollX; 1136 dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; 1137 1138 mScroller.startScroll(scrollX, mScrollY, dx, 0); 1139 postInvalidateOnAnimation(); 1140 } else { 1141 if (!mScroller.isFinished()) { 1142 mScroller.abortAnimation(); 1143 } 1144 scrollBy(dx, dy); 1145 } 1146 mLastScroll = AnimationUtils.currentAnimationTimeMillis(); 1147 } 1148 1149 /** 1150 * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 1151 * 1152 * @param x the position where to scroll on the X axis 1153 * @param y the position where to scroll on the Y axis 1154 */ 1155 public final void smoothScrollTo(int x, int y) { 1156 smoothScrollBy(x - mScrollX, y - mScrollY); 1157 } 1158 1159 /** 1160 * <p>The scroll range of a scroll view is the overall width of all of its 1161 * children.</p> 1162 */ 1163 @Override 1164 protected int computeHorizontalScrollRange() { 1165 final int count = getChildCount(); 1166 final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; 1167 if (count == 0) { 1168 return contentWidth; 1169 } 1170 1171 int scrollRange = getChildAt(0).getRight(); 1172 final int scrollX = mScrollX; 1173 final int overscrollRight = Math.max(0, scrollRange - contentWidth); 1174 if (scrollX < 0) { 1175 scrollRange -= scrollX; 1176 } else if (scrollX > overscrollRight) { 1177 scrollRange += scrollX - overscrollRight; 1178 } 1179 1180 return scrollRange; 1181 } 1182 1183 @Override 1184 protected int computeHorizontalScrollOffset() { 1185 return Math.max(0, super.computeHorizontalScrollOffset()); 1186 } 1187 1188 @Override 1189 protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { 1190 ViewGroup.LayoutParams lp = child.getLayoutParams(); 1191 1192 int childWidthMeasureSpec; 1193 int childHeightMeasureSpec; 1194 1195 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop 1196 + mPaddingBottom, lp.height); 1197 1198 childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 1199 1200 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1201 } 1202 1203 @Override 1204 protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, 1205 int parentHeightMeasureSpec, int heightUsed) { 1206 final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); 1207 1208 final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, 1209 mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin 1210 + heightUsed, lp.height); 1211 final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( 1212 lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 1213 1214 child.measure(childWidthMeasureSpec, childHeightMeasureSpec); 1215 } 1216 1217 @Override 1218 public void computeScroll() { 1219 if (mScroller.computeScrollOffset()) { 1220 // This is called at drawing time by ViewGroup. We don't want to 1221 // re-show the scrollbars at this point, which scrollTo will do, 1222 // so we replicate most of scrollTo here. 1223 // 1224 // It's a little odd to call onScrollChanged from inside the drawing. 1225 // 1226 // It is, except when you remember that computeScroll() is used to 1227 // animate scrolling. So unless we want to defer the onScrollChanged() 1228 // until the end of the animated scrolling, we don't really have a 1229 // choice here. 1230 // 1231 // I agree. The alternative, which I think would be worse, is to post 1232 // something and tell the subclasses later. This is bad because there 1233 // will be a window where mScrollX/Y is different from what the app 1234 // thinks it is. 1235 // 1236 int oldX = mScrollX; 1237 int oldY = mScrollY; 1238 int x = mScroller.getCurrX(); 1239 int y = mScroller.getCurrY(); 1240 1241 if (oldX != x || oldY != y) { 1242 final int range = getScrollRange(); 1243 final int overscrollMode = getOverScrollMode(); 1244 final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || 1245 (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); 1246 1247 overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, 1248 mOverflingDistance, 0, false); 1249 onScrollChanged(mScrollX, mScrollY, oldX, oldY); 1250 1251 if (canOverscroll) { 1252 if (x < 0 && oldX >= 0) { 1253 mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); 1254 } else if (x > range && oldX <= range) { 1255 mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); 1256 } 1257 } 1258 } 1259 1260 if (!awakenScrollBars()) { 1261 postInvalidateOnAnimation(); 1262 } 1263 } 1264 } 1265 1266 /** 1267 * Scrolls the view to the given child. 1268 * 1269 * @param child the View to scroll to 1270 */ 1271 private void scrollToChild(View child) { 1272 child.getDrawingRect(mTempRect); 1273 1274 /* Offset from child's local coordinates to ScrollView coordinates */ 1275 offsetDescendantRectToMyCoords(child, mTempRect); 1276 1277 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1278 1279 if (scrollDelta != 0) { 1280 scrollBy(scrollDelta, 0); 1281 } 1282 } 1283 1284 /** 1285 * If rect is off screen, scroll just enough to get it (or at least the 1286 * first screen size chunk of it) on screen. 1287 * 1288 * @param rect The rectangle. 1289 * @param immediate True to scroll immediately without animation 1290 * @return true if scrolling was performed 1291 */ 1292 private boolean scrollToChildRect(Rect rect, boolean immediate) { 1293 final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); 1294 final boolean scroll = delta != 0; 1295 if (scroll) { 1296 if (immediate) { 1297 scrollBy(delta, 0); 1298 } else { 1299 smoothScrollBy(delta, 0); 1300 } 1301 } 1302 return scroll; 1303 } 1304 1305 /** 1306 * Compute the amount to scroll in the X direction in order to get 1307 * a rectangle completely on the screen (or, if taller than the screen, 1308 * at least the first screen size chunk of it). 1309 * 1310 * @param rect The rect. 1311 * @return The scroll delta. 1312 */ 1313 protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { 1314 if (getChildCount() == 0) return 0; 1315 1316 int width = getWidth(); 1317 int screenLeft = getScrollX(); 1318 int screenRight = screenLeft + width; 1319 1320 int fadingEdge = getHorizontalFadingEdgeLength(); 1321 1322 // leave room for left fading edge as long as rect isn't at very left 1323 if (rect.left > 0) { 1324 screenLeft += fadingEdge; 1325 } 1326 1327 // leave room for right fading edge as long as rect isn't at very right 1328 if (rect.right < getChildAt(0).getWidth()) { 1329 screenRight -= fadingEdge; 1330 } 1331 1332 int scrollXDelta = 0; 1333 1334 if (rect.right > screenRight && rect.left > screenLeft) { 1335 // need to move right to get it in view: move right just enough so 1336 // that the entire rectangle is in view (or at least the first 1337 // screen size chunk). 1338 1339 if (rect.width() > width) { 1340 // just enough to get screen size chunk on 1341 scrollXDelta += (rect.left - screenLeft); 1342 } else { 1343 // get entire rect at right of screen 1344 scrollXDelta += (rect.right - screenRight); 1345 } 1346 1347 // make sure we aren't scrolling beyond the end of our content 1348 int right = getChildAt(0).getRight(); 1349 int distanceToRight = right - screenRight; 1350 scrollXDelta = Math.min(scrollXDelta, distanceToRight); 1351 1352 } else if (rect.left < screenLeft && rect.right < screenRight) { 1353 // need to move right to get it in view: move right just enough so that 1354 // entire rectangle is in view (or at least the first screen 1355 // size chunk of it). 1356 1357 if (rect.width() > width) { 1358 // screen size chunk 1359 scrollXDelta -= (screenRight - rect.right); 1360 } else { 1361 // entire rect at left 1362 scrollXDelta -= (screenLeft - rect.left); 1363 } 1364 1365 // make sure we aren't scrolling any further than the left our content 1366 scrollXDelta = Math.max(scrollXDelta, -getScrollX()); 1367 } 1368 return scrollXDelta; 1369 } 1370 1371 @Override 1372 public void requestChildFocus(View child, View focused) { 1373 if (!mIsLayoutDirty) { 1374 scrollToChild(focused); 1375 } else { 1376 // The child may not be laid out yet, we can't compute the scroll yet 1377 mChildToScrollTo = focused; 1378 } 1379 super.requestChildFocus(child, focused); 1380 } 1381 1382 1383 /** 1384 * When looking for focus in children of a scroll view, need to be a little 1385 * more careful not to give focus to something that is scrolled off screen. 1386 * 1387 * This is more expensive than the default {@link android.view.ViewGroup} 1388 * implementation, otherwise this behavior might have been made the default. 1389 */ 1390 @Override 1391 protected boolean onRequestFocusInDescendants(int direction, 1392 Rect previouslyFocusedRect) { 1393 1394 // convert from forward / backward notation to up / down / left / right 1395 // (ugh). 1396 if (direction == View.FOCUS_FORWARD) { 1397 direction = View.FOCUS_RIGHT; 1398 } else if (direction == View.FOCUS_BACKWARD) { 1399 direction = View.FOCUS_LEFT; 1400 } 1401 1402 final View nextFocus = previouslyFocusedRect == null ? 1403 FocusFinder.getInstance().findNextFocus(this, null, direction) : 1404 FocusFinder.getInstance().findNextFocusFromRect(this, 1405 previouslyFocusedRect, direction); 1406 1407 if (nextFocus == null) { 1408 return false; 1409 } 1410 1411 if (isOffScreen(nextFocus)) { 1412 return false; 1413 } 1414 1415 return nextFocus.requestFocus(direction, previouslyFocusedRect); 1416 } 1417 1418 @Override 1419 public boolean requestChildRectangleOnScreen(View child, Rect rectangle, 1420 boolean immediate) { 1421 // offset into coordinate space of this scroll view 1422 rectangle.offset(child.getLeft() - child.getScrollX(), 1423 child.getTop() - child.getScrollY()); 1424 1425 return scrollToChildRect(rectangle, immediate); 1426 } 1427 1428 @Override 1429 public void requestLayout() { 1430 mIsLayoutDirty = true; 1431 super.requestLayout(); 1432 } 1433 1434 @Override 1435 protected void onLayout(boolean changed, int l, int t, int r, int b) { 1436 super.onLayout(changed, l, t, r, b); 1437 mIsLayoutDirty = false; 1438 // Give a child focus if it needs it 1439 if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { 1440 scrollToChild(mChildToScrollTo); 1441 } 1442 mChildToScrollTo = null; 1443 1444 // Calling this with the present values causes it to re-claim them 1445 scrollTo(mScrollX, mScrollY); 1446 } 1447 1448 @Override 1449 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 1450 super.onSizeChanged(w, h, oldw, oldh); 1451 1452 View currentFocused = findFocus(); 1453 if (null == currentFocused || this == currentFocused) 1454 return; 1455 1456 final int maxJump = mRight - mLeft; 1457 1458 if (isWithinDeltaOfScreen(currentFocused, maxJump)) { 1459 currentFocused.getDrawingRect(mTempRect); 1460 offsetDescendantRectToMyCoords(currentFocused, mTempRect); 1461 int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); 1462 doScrollX(scrollDelta); 1463 } 1464 } 1465 1466 /** 1467 * Return true if child is a descendant of parent, (or equal to the parent). 1468 */ 1469 private static boolean isViewDescendantOf(View child, View parent) { 1470 if (child == parent) { 1471 return true; 1472 } 1473 1474 final ViewParent theParent = child.getParent(); 1475 return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); 1476 } 1477 1478 /** 1479 * Fling the scroll view 1480 * 1481 * @param velocityX The initial velocity in the X direction. Positive 1482 * numbers mean that the finger/cursor is moving down the screen, 1483 * which means we want to scroll towards the left. 1484 */ 1485 public void fling(int velocityX) { 1486 if (getChildCount() > 0) { 1487 int width = getWidth() - mPaddingRight - mPaddingLeft; 1488 int right = getChildAt(0).getWidth(); 1489 1490 mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, 1491 Math.max(0, right - width), 0, 0, width/2, 0); 1492 1493 final boolean movingRight = velocityX > 0; 1494 1495 View currentFocused = findFocus(); 1496 View newFocused = findFocusableViewInMyBounds(movingRight, 1497 mScroller.getFinalX(), currentFocused); 1498 1499 if (newFocused == null) { 1500 newFocused = this; 1501 } 1502 1503 if (newFocused != currentFocused) { 1504 newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); 1505 } 1506 1507 postInvalidateOnAnimation(); 1508 } 1509 } 1510 1511 /** 1512 * {@inheritDoc} 1513 * 1514 * <p>This version also clamps the scrolling to the bounds of our child. 1515 */ 1516 @Override 1517 public void scrollTo(int x, int y) { 1518 // we rely on the fact the View.scrollBy calls scrollTo. 1519 if (getChildCount() > 0) { 1520 View child = getChildAt(0); 1521 x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); 1522 y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); 1523 if (x != mScrollX || y != mScrollY) { 1524 super.scrollTo(x, y); 1525 } 1526 } 1527 } 1528 1529 @Override 1530 public void setOverScrollMode(int mode) { 1531 if (mode != OVER_SCROLL_NEVER) { 1532 if (mEdgeGlowLeft == null) { 1533 Context context = getContext(); 1534 mEdgeGlowLeft = new EdgeEffect(context); 1535 mEdgeGlowRight = new EdgeEffect(context); 1536 } 1537 } else { 1538 mEdgeGlowLeft = null; 1539 mEdgeGlowRight = null; 1540 } 1541 super.setOverScrollMode(mode); 1542 } 1543 1544 @SuppressWarnings({"SuspiciousNameCombination"}) 1545 @Override 1546 public void draw(Canvas canvas) { 1547 super.draw(canvas); 1548 if (mEdgeGlowLeft != null) { 1549 final int scrollX = mScrollX; 1550 if (!mEdgeGlowLeft.isFinished()) { 1551 final int restoreCount = canvas.save(); 1552 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1553 1554 canvas.rotate(270); 1555 canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); 1556 mEdgeGlowLeft.setSize(height, getWidth()); 1557 if (mEdgeGlowLeft.draw(canvas)) { 1558 postInvalidateOnAnimation(); 1559 } 1560 canvas.restoreToCount(restoreCount); 1561 } 1562 if (!mEdgeGlowRight.isFinished()) { 1563 final int restoreCount = canvas.save(); 1564 final int width = getWidth(); 1565 final int height = getHeight() - mPaddingTop - mPaddingBottom; 1566 1567 canvas.rotate(90); 1568 canvas.translate(-mPaddingTop, 1569 -(Math.max(getScrollRange(), scrollX) + width)); 1570 mEdgeGlowRight.setSize(height, width); 1571 if (mEdgeGlowRight.draw(canvas)) { 1572 postInvalidateOnAnimation(); 1573 } 1574 canvas.restoreToCount(restoreCount); 1575 } 1576 } 1577 } 1578 1579 private static int clamp(int n, int my, int child) { 1580 if (my >= child || n < 0) { 1581 return 0; 1582 } 1583 if ((my + n) > child) { 1584 return child - my; 1585 } 1586 return n; 1587 } 1588 } 1589
