Android中实现上下左右都可滑动的ScrollView

从网上down下来的，以免忘记特此标记：
import java.util.List;  import android.content.Context;  import android.graphics.Rect;  import android.util.AttributeSet;  import android.view.FocusFinder;  import android.view.KeyEvent;  import android.view.MotionEvent;  import android.view.VelocityTracker;  import android.view.View;  import android.view.ViewConfiguration;  import android.view.ViewGroup;  import android.view.ViewParent;  import android.view.animation.AnimationUtils;  import android.widget.FrameLayout;  import android.widget.Scroller;  /**  * Reference to ScrollView and HorizontalScrollView  */  public class HVScrollView extends FrameLayout {  static final int ANIMATED_SCROLL_GAP = 250;  static final float MAX_SCROLL_FACTOR = 0.5f;  private long mLastScroll;  private final Rect mTempRect = new Rect();  private Scroller mScroller;  /**  * Flag to indicate that we are moving focus ourselves. This is so the  * code that watches for focus changes initiated outside this ScrollView  * knows that it does not have to do anything.  */  private boolean mScrollViewMovedFocus;  /**  * Position of the last motion event.  */  private float mLastMotionY;  private float mLastMotionX;  /**  * True when the layout has changed but the traversal has not come through yet.  * Ideally the view hierarchy would keep track of this for us.  */  private boolean mIsLayoutDirty = true;  /**  * The child to give focus to in the event that a child has requested focus while the  * layout is dirty. This prevents the scroll from being wrong if the child has not been  * laid out before requesting focus.  */  private View mChildToScrollTo = null;  /**  * True if the user is currently dragging this ScrollView around. This is  * not the same as 'is being flinged', which can be checked by  * mScroller.isFinished() (flinging begins when the user lifts his finger).  */  private boolean mIsBeingDragged = false;  /**  * Determines speed during touch scrolling  */  private VelocityTracker mVelocityTracker;  /**  * When set to true, the scroll view measure its child to make it fill the currently  * visible area.  */  private boolean mFillViewport;  /**  * Whether arrow scrolling is animated.  */  private boolean mSmoothScrollingEnabled = true;  private int mTouchSlop;  private int mMinimumVelocity;  private int mMaximumVelocity;  /**  * ID of the active pointer. This is used to retain consistency during  * drags/flings if multiple pointers are used.  */  private int mActivePointerId = INVALID_POINTER;  /**  * Sentinel value for no current active pointer.  * Used by {@link #mActivePointerId}.  */  private static final int INVALID_POINTER = -1;  private boolean mFlingEnabled = true;  public HVScrollView(Context context) {  this(context, null);  }  public HVScrollView(Context context, AttributeSet attrs) {  super(context, attrs);  initScrollView();  }  @Override  protected float getTopFadingEdgeStrength() {  if (getChildCount() == 0) {  return 0.0f;  }  final int length = getVerticalFadingEdgeLength();  if (getScrollY() < length) {  return getScrollY() / (float) length;  }  return 1.0f;  }  @Override  protected float getLeftFadingEdgeStrength() {  if (getChildCount() == 0) {  return 0.0f;  }  final int length = getHorizontalFadingEdgeLength();  if (getScrollX() < length) {  return getScrollX() / (float) length;  }  return 1.0f;  }  @Override  protected float getRightFadingEdgeStrength() {  if (getChildCount() == 0) {  return 0.0f;  }  final int length = getHorizontalFadingEdgeLength();  final int rightEdge = getWidth() - getPaddingRight();  final int span = getChildAt(0).getRight() - getScrollX() - rightEdge;  if (span < length) {  return span / (float) length;  }  return 1.0f;  }  @Override  protected float getBottomFadingEdgeStrength() {  if (getChildCount() == 0) {  return 0.0f;  }  final int length = getVerticalFadingEdgeLength();  final int bottomEdge = getHeight() - getPaddingBottom();  final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge;  if (span < length) {  return span / (float) length;  }  return 1.0f;  }  /**  * @return The maximum amount this scroll view will scroll in response to  *   an arrow event.  */   public int getMaxScrollAmountV() {  return (int) (MAX_SCROLL_FACTOR * (getBottom() - getTop()));  }  public int getMaxScrollAmountH() {  return (int) (MAX_SCROLL_FACTOR * (getRight() - getLeft()));  }  private void initScrollView() {  mScroller = new Scroller(getContext());  setFocusable(true);  setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);  setWillNotDraw(false);  final ViewConfiguration configuration = ViewConfiguration.get(getContext());  mTouchSlop = configuration.getScaledTouchSlop();  mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();  mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();  }  @Override  public void addView(View child) {  if (getChildCount() > 0) {  throw new IllegalStateException("ScrollView can host only one direct child");  }  super.addView(child);  }  @Override  public void addView(View child, int index) {  if (getChildCount() > 0) {  throw new IllegalStateException("ScrollView can host only one direct child");  }  super.addView(child, index);  }  @Override  public void addView(View child, ViewGroup.LayoutParams params) {  if (getChildCount() > 0) {  throw new IllegalStateException("ScrollView can host only one direct child");  }  super.addView(child, params);  }  @Override  public void addView(View child, int index, ViewGroup.LayoutParams params) {  if (getChildCount() > 0) {  throw new IllegalStateException("ScrollView can host only one direct child");  }  super.addView(child, index, params);  }  /**  * @return Returns true this ScrollView can be scrolled  */  private boolean canScrollV() {  View child = getChildAt(0);  if (child != null) {  int childHeight = child.getHeight();  return getHeight() < childHeight + getPaddingTop() + getPaddingBottom();  }  return false;  }  private boolean canScrollH() {  View child = getChildAt(0);  if (child != null) {  int childWidth = child.getWidth();  return getWidth() < childWidth + getPaddingLeft() + getPaddingRight() ;  }  return false;  }  /**  * Indicates whether this ScrollView's content is stretched to fill the viewport.  *  * @return True if the content fills the viewport, false otherwise.  */  public boolean isFillViewport() {  return mFillViewport;  }  /**  * Indicates this ScrollView whether it should stretch its content height to fill  * the viewport or not.  *  * @param fillViewport True to stretch the content's height to the viewport's  *        boundaries, false otherwise.  */  public void setFillViewport(boolean fillViewport) {  if (fillViewport != mFillViewport) {  mFillViewport = fillViewport;  requestLayout();  }  }  /**  * @return Whether arrow scrolling will animate its transition.  */  public boolean isSmoothScrollingEnabled() {  return mSmoothScrollingEnabled;  }  /**  * Set whether arrow scrolling will animate its transition.  * @param smoothScrollingEnabled whether arrow scrolling will animate its transition  */  public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {  mSmoothScrollingEnabled = smoothScrollingEnabled;  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  super.onMeasure(widthMeasureSpec, heightMeasureSpec);  if (!mFillViewport) {  return;  }  final int heightMode = MeasureSpec.getMode(heightMeasureSpec);  final int widthMode = MeasureSpec.getMode(widthMeasureSpec);  if (heightMode == MeasureSpec.UNSPECIFIED && widthMode == MeasureSpec.UNSPECIFIED) {  return;  }  if (getChildCount() > 0) {  final View child = getChildAt(0);  int height = getMeasuredHeight();  int width = getMeasuredWidth();  if (child.getMeasuredHeight() < height || child.getMeasuredWidth() < width) {  width -= getPaddingLeft();  width -= getPaddingRight();  int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);  height -= getPaddingTop();  height -= getPaddingBottom();  int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);  child.measure(childWidthMeasureSpec, childHeightMeasureSpec);  }  }  }  @Override  public boolean dispatchKeyEvent(KeyEvent event) {  // Let the focused view and/or our descendants get the key first  return super.dispatchKeyEvent(event) || executeKeyEvent(event);  }  /**  * You can call this function yourself to have the scroll view perform  * scrolling from a key event, just as if the event had been dispatched to  * it by the view hierarchy.  *  * @param event The key event to execute.  * @return Return true if the event was handled, else false.  */  public boolean executeKeyEvent(KeyEvent event) {  mTempRect.setEmpty();  boolean handled = false;  if (event.getAction() == KeyEvent.ACTION_DOWN) {  switch (event.getKeyCode()) {  case KeyEvent.KEYCODE_DPAD_LEFT:  if(canScrollH()){  if (!event.isAltPressed()) {  handled = arrowScrollH(View.FOCUS_LEFT);  } else {  handled = fullScrollH(View.FOCUS_LEFT);  }  }  break;  case KeyEvent.KEYCODE_DPAD_RIGHT:  if(canScrollH()){  if (!event.isAltPressed()) {  handled = arrowScrollH(View.FOCUS_RIGHT);  } else {  handled = fullScrollH(View.FOCUS_RIGHT);  }  }  break;  case KeyEvent.KEYCODE_DPAD_UP:  if(canScrollV()){  if (!event.isAltPressed()) {  handled = arrowScrollV(View.FOCUS_UP);  } else {  handled = fullScrollV(View.FOCUS_UP);  }  }  break;  case KeyEvent.KEYCODE_DPAD_DOWN:  if(canScrollV()){  if (!event.isAltPressed()) {  handled = arrowScrollV(View.FOCUS_DOWN);  } else {  handled = fullScrollV(View.FOCUS_DOWN);  }  }  break;  }  }  return handled;  }  private boolean inChild(int x, int y) {  if (getChildCount() > 0) {  final int scrollX = getScrollX();  final int scrollY = getScrollY();  final View child = getChildAt(0);  return !(y < child.getTop() - scrollY  || y >= child.getBottom() - scrollY  || x < child.getLeft() - scrollX  || x >= child.getRight() - scrollX);  }  return false;  }  @Override  public boolean onInterceptTouchEvent(MotionEvent ev) {  /*  * This method JUST determines whether we want to intercept the motion.  * If we return true, onMotionEvent will be called and we do the actual  * scrolling there.  */  /*  * Shortcut the most recurring case: the user is in the dragging  * state and he is moving his finger.  We want to intercept this  * motion.  */  final int action = ev.getAction();  if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {  return true;  }  switch (action & MotionEvent.ACTION_MASK) {  case MotionEvent.ACTION_MOVE: {  /*  * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check  * whether the user has moved far enough from his original down touch.  */  /*  * Locally do absolute value. mLastMotionY is set to the y value  * of the down event.  */  final int activePointerId = mActivePointerId;  if (activePointerId == INVALID_POINTER) {  // If we don't have a valid id, the touch down wasn't on content.  break;  }  final int pointerIndex = ev.findPointerIndex(activePointerId);  final float y = ev.getY(pointerIndex);  final int yDiff = (int) Math.abs(y - mLastMotionY);  if (yDiff > mTouchSlop) {  mIsBeingDragged = true;  mLastMotionY = y;  }  final float x = ev.getX(pointerIndex);  final int xDiff = (int) Math.abs(x - mLastMotionX);  if (xDiff > mTouchSlop) {  mIsBeingDragged = true;  mLastMotionX = x;  }  break;  }  case MotionEvent.ACTION_DOWN: {  final float x = ev.getX();  final float y = ev.getY();  if (!inChild((int)x, (int) y)) {  mIsBeingDragged = false;  break;  }  /*  * Remember location of down touch.  * ACTION_DOWN always refers to pointer index 0.  */  mLastMotionY = y;  mLastMotionX = x;  mActivePointerId = ev.getPointerId(0);  /*  * If being flinged and user touches the screen, initiate drag;  * otherwise don't.  mScroller.isFinished should be false when  * being flinged.  */  mIsBeingDragged = !mScroller.isFinished();  break;  }  case MotionEvent.ACTION_CANCEL:  case MotionEvent.ACTION_UP:  /* Release the drag */  mIsBeingDragged = false;  mActivePointerId = INVALID_POINTER;  break;  case MotionEvent.ACTION_POINTER_UP:  onSecondaryPointerUp(ev);  break;  }  /*  * The only time we want to intercept motion events is if we are in the  * drag mode.  */  return mIsBeingDragged;  }  @Override  public boolean onTouchEvent(MotionEvent ev) {  if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {  // Don't handle edge touches immediately -- they may actually belong to one of our  // descendants.  return false;  }  if (mVelocityTracker == null) {  mVelocityTracker = VelocityTracker.obtain();  }  mVelocityTracker.addMovement(ev);  final int action = ev.getAction();  switch (action & MotionEvent.ACTION_MASK) {  case MotionEvent.ACTION_DOWN: {  final float x = ev.getX();  final float y = ev.getY();  if (!(mIsBeingDragged = inChild((int) x, (int) y))) {  return false;  }  /*  * If being flinged and user touches, stop the fling. isFinished  * will be false if being flinged.  */  if (!mScroller.isFinished()) {  mScroller.abortAnimation();  }  // Remember where the motion event started  mLastMotionY = y;  mLastMotionX = x;  mActivePointerId = ev.getPointerId(0);  break;  }  case MotionEvent.ACTION_MOVE:  if (mIsBeingDragged) {  // Scroll to follow the motion event  final int activePointerIndex = ev.findPointerIndex(mActivePointerId);  final float y = ev.getY(activePointerIndex);  final int deltaY = (int) (mLastMotionY - y);  mLastMotionY = y;  final float x = ev.getX(activePointerIndex);  final int deltaX = (int) (mLastMotionX - x);  mLastMotionX = x;  scrollBy(deltaX, deltaY);  }  break;  case MotionEvent.ACTION_UP:   if (mIsBeingDragged) {  if(mFlingEnabled){  final VelocityTracker velocityTracker = mVelocityTracker;  velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);  int initialVelocitx = (int) velocityTracker.getXVelocity();  int initialVelocity = (int) velocityTracker.getYVelocity(); //int initialVelocitx = (int) velocityTracker.getXVelocity(mActivePointerId);  //int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId);  if (getChildCount() > 0) {  if(Math.abs(initialVelocitx) > initialVelocitx || Math.abs(initialVelocity) > mMinimumVelocity) {  fling(-initialVelocitx, -initialVelocity);  }  }  }  mActivePointerId = INVALID_POINTER;  mIsBeingDragged = false;  if (mVelocityTracker != null) {  mVelocityTracker.recycle();  mVelocityTracker = null;  }  }  break;  case MotionEvent.ACTION_CANCEL:  if (mIsBeingDragged && getChildCount() > 0) {  mActivePointerId = INVALID_POINTER;  mIsBeingDragged = false;  if (mVelocityTracker != null) {  mVelocityTracker.recycle();  mVelocityTracker = null;  }  }  break;  case MotionEvent.ACTION_POINTER_UP:  onSecondaryPointerUp(ev);  break;  }  return true;  }  private void onSecondaryPointerUp(MotionEvent ev) {  final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >>  MotionEvent.ACTION_POINTER_ID_SHIFT;  final int pointerId = ev.getPointerId(pointerIndex);  if (pointerId == mActivePointerId) {  // This was our active pointer going up. Choose a new  // active pointer and adjust accordingly.  final int newPointerIndex = pointerIndex == 0 ? 1 : 0;  mLastMotionX = ev.getX(newPointerIndex);  mLastMotionY = ev.getY(newPointerIndex);  mActivePointerId = ev.getPointerId(newPointerIndex);  if (mVelocityTracker != null) {  mVelocityTracker.clear();  }  }  } /**  * <p>  * Finds the next focusable component that fits in the specified bounds.  * </p>  *  * @param topFocus look for a candidate is the one at the top of the bounds  *                 if topFocus is true, or at the bottom of the bounds if topFocus is  *                 false  * @param top      the top offset of the bounds in which a focusable must be  *                 found  * @param bottom   the bottom offset of the bounds in which a focusable must  *                 be found  * @return the next focusable component in the bounds or null if none can  *         be found  */  private View findFocusableViewInBoundsV(boolean topFocus, int top, int bottom) {  List<View> focusables = getFocusables(View.FOCUS_FORWARD);  View focusCandidate = null;  /*  * A fully contained focusable is one where its top is below the bound's  * top, and its bottom is above the bound's bottom. A partially  * contained focusable is one where some part of it is within the  * bounds, but it also has some part that is not within bounds.  A fully contained  * focusable is preferred to a partially contained focusable.  */  boolean foundFullyContainedFocusable = false;  int count = focusables.size();  for (int i = 0; i < count; i++) {  View view = focusables.get(i);  int viewTop = view.getTop();  int viewBottom = view.getBottom();  if (top < viewBottom && viewTop < bottom) {  /*  * the focusable is in the target area, it is a candidate for  * focusing  */  final boolean viewIsFullyContained = (top < viewTop) &&  (viewBottom < bottom);  if (focusCandidate == null) {  /* No candidate, take this one */  focusCandidate = view;  foundFullyContainedFocusable = viewIsFullyContained;  } else {  final boolean viewIsCloserToBoundary =  (topFocus && viewTop < focusCandidate.getTop()) ||  (!topFocus && viewBottom > focusCandidate  .getBottom());  if (foundFullyContainedFocusable) {  if (viewIsFullyContained && viewIsCloserToBoundary) {  /*  * We're dealing with only fully contained views, so  * it has to be closer to the boundary to beat our  * candidate  */  focusCandidate = view;  }  } else {  if (viewIsFullyContained) {  /* Any fully contained view beats a partially contained view */  focusCandidate = view;  foundFullyContainedFocusable = true;  } else if (viewIsCloserToBoundary) {  /*  * Partially contained view beats another partially  * contained view if it's closer  */  focusCandidate = view;  }  }  }  }  }  return focusCandidate;  }  private View findFocusableViewInBoundsH(boolean leftFocus, int left, int right) {  List<View> focusables = getFocusables(View.FOCUS_FORWARD);  View focusCandidate = null;  /*  * A fully contained focusable is one where its left is below the bound's  * left, and its right is above the bound's right. A partially  * contained focusable is one where some part of it is within the  * bounds, but it also has some part that is not within bounds.  A fully contained  * focusable is preferred to a partially contained focusable.  */  boolean foundFullyContainedFocusable = false;  int count = focusables.size();  for (int i = 0; i < count; i++) {  View view = focusables.get(i);  int viewLeft = view.getLeft();  int viewRight = view.getRight();  if (left < viewRight && viewLeft < right) {  /*  * the focusable is in the target area, it is a candidate for  * focusing  */  final boolean viewIsFullyContained = (left < viewLeft) &&  (viewRight < right);  if (focusCandidate == null) {  /* No candidate, take this one */  focusCandidate = view;  foundFullyContainedFocusable = viewIsFullyContained;  } else {  final boolean viewIsCloserToBoundary =  (leftFocus && viewLeft < focusCandidate.getLeft()) ||  (!leftFocus && viewRight > focusCandidate.getRight());  if (foundFullyContainedFocusable) {  if (viewIsFullyContained && viewIsCloserToBoundary) {  /*  * We're dealing with only fully contained views, so  * it has to be closer to the boundary to beat our  * candidate  */  focusCandidate = view;  }  } else {  if (viewIsFullyContained) {  /* Any fully contained view beats a partially contained view */  focusCandidate = view;  foundFullyContainedFocusable = true;  } else if (viewIsCloserToBoundary) {  /*  * Partially contained view beats another partially  * contained view if it's closer  */  focusCandidate = view;  }  }  }  }  }  return focusCandidate;  }  /**  * <p>Handles scrolling in response to a "home/end" shortcut press. This  * method will scroll the view to the top or bottom and give the focus  * to the topmost/bottommost component in the new visible area. If no  * component is a good candidate for focus, this scrollview reclaims the  * focus.</p>  *  * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}  *                  to go the top of the view or  *                  {@link android.view.View#FOCUS_DOWN} to go the bottom  * @return true if the key event is consumed by this method, false otherwise  */  public boolean fullScrollV(int direction) {  boolean down = direction == View.FOCUS_DOWN;  int height = getHeight();  mTempRect.top = 0;  mTempRect.bottom = height;  if (down) {  int count = getChildCount();  if (count > 0) {  View view = getChildAt(count - 1);  mTempRect.bottom = view.getBottom();  mTempRect.top = mTempRect.bottom - height;  }  }  return scrollAndFocusV(direction, mTempRect.top, mTempRect.bottom);  }  public boolean fullScrollH(int direction) {  boolean right = direction == View.FOCUS_RIGHT;  int width = getWidth();  mTempRect.left = 0;  mTempRect.right = width;  if (right) {  int count = getChildCount();  if (count > 0) {  View view = getChildAt(0);  mTempRect.right = view.getRight();  mTempRect.left = mTempRect.right - width;  }  }  return scrollAndFocusH(direction, mTempRect.left, mTempRect.right);  }  /**  * <p>Scrolls the view to make the area defined by <code>top</code> and  * <code>bottom</code> visible. This method attempts to give the focus  * to a component visible in this area. If no component can be focused in  * the new visible area, the focus is reclaimed by this scrollview.</p>  *  * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}  *                  to go upward  *                  {@link android.view.View#FOCUS_DOWN} to downward  * @param top       the top offset of the new area to be made visible  * @param bottom    the bottom offset of the new area to be made visible  * @return true if the key event is consumed by this method, false otherwise  */  private boolean scrollAndFocusV(int direction, int top, int bottom) {  boolean handled = true;  int height = getHeight();  int containerTop = getScrollY();  int containerBottom = containerTop + height;  boolean up = direction == View.FOCUS_UP;  View newFocused = findFocusableViewInBoundsV(up, top, bottom);  if (newFocused == null) {  newFocused = this;  }  if (top >= containerTop && bottom <= containerBottom) {  handled = false;  } else {  int delta = up ? (top - containerTop) : (bottom - containerBottom);  doScrollY(delta);  }  if (newFocused != findFocus() && newFocused.requestFocus(direction)) {  mScrollViewMovedFocus = true;  mScrollViewMovedFocus = false;  }  return handled;  }  private boolean scrollAndFocusH(int direction, int left, int right) {  boolean handled = true;  int width = getWidth();  int containerLeft = getScrollX();  int containerRight = containerLeft + width;  boolean goLeft = direction == View.FOCUS_LEFT;  View newFocused = findFocusableViewInBoundsH(goLeft, left, right);  if (newFocused == null) {  newFocused = this;  }  if (left >= containerLeft && right <= containerRight) {  handled = false;  } else {  int delta = goLeft ? (left - containerLeft) : (right - containerRight);  doScrollX(delta);  }  if (newFocused != findFocus() && newFocused.requestFocus(direction)) {  mScrollViewMovedFocus = true;  mScrollViewMovedFocus = false;  }  return handled;  }  /**  * Handle scrolling in response to an up or down arrow click.  *  * @param direction The direction corresponding to the arrow key that was  *                  pressed  * @return True if we consumed the event, false otherwise  */  public boolean arrowScrollV(int direction) {  View currentFocused = findFocus();  if (currentFocused == this) currentFocused = null;  View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);  final int maxJump = getMaxScrollAmountV();  if (nextFocused != null && isWithinDeltaOfScreenV(nextFocused, maxJump, getHeight())) {  nextFocused.getDrawingRect(mTempRect);  offsetDescendantRectToMyCoords(nextFocused, mTempRect);  int scrollDelta = computeScrollDeltaToGetChildRectOnScreenV(mTempRect);  doScrollY(scrollDelta);  nextFocused.requestFocus(direction);  } else {  // no new focus  int scrollDelta = maxJump;  if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {  scrollDelta = getScrollY();  } else if (direction == View.FOCUS_DOWN) {  if (getChildCount() > 0) {  int daBottom = getChildAt(0).getBottom();  int screenBottom = getScrollY() + getHeight();  if (daBottom - screenBottom < maxJump) {  scrollDelta = daBottom - screenBottom;  }  }  }  if (scrollDelta == 0) {  return false;  }  doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);  }  if (currentFocused != null && currentFocused.isFocused()  && isOffScreenV(currentFocused)) {  // previously focused item still has focus and is off screen, give  // it up (take it back to ourselves)  // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are  // sure to  // get it)  final int descendantFocusability = getDescendantFocusability();  // save  setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);  requestFocus();  setDescendantFocusability(descendantFocusability);  // restore  }  return true;  }  public boolean arrowScrollH(int direction) {  View currentFocused = findFocus();  if (currentFocused == this) currentFocused = null;  View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);  final int maxJump = getMaxScrollAmountH();  if (nextFocused != null && isWithinDeltaOfScreenH(nextFocused, maxJump)) {  nextFocused.getDrawingRect(mTempRect);  offsetDescendantRectToMyCoords(nextFocused, mTempRect);  int scrollDelta = computeScrollDeltaToGetChildRectOnScreenH(mTempRect);  doScrollX(scrollDelta);  nextFocused.requestFocus(direction);  } else {  // no new focus  int scrollDelta = maxJump;  if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) {  scrollDelta = getScrollX();  } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) {  int daRight = getChildAt(0).getRight();  int screenRight = getScrollX() + getWidth();  if (daRight - screenRight < maxJump) {  scrollDelta = daRight - screenRight;  }  }  if (scrollDelta == 0) {  return false;  }  doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta);  }  if (currentFocused != null && currentFocused.isFocused()  && isOffScreenH(currentFocused)) {  // previously focused item still has focus and is off screen, give  // it up (take it back to ourselves)  // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are  // sure to  // get it)  final int descendantFocusability = getDescendantFocusability();  // save  setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);  requestFocus();  setDescendantFocusability(descendantFocusability);  // restore  }  return true;  }/**  * @return whether the descendant of this scroll view is scrolled off  *  screen.  */  private boolean isOffScreenV(View descendant) {  return !isWithinDeltaOfScreenV(descendant, 0, getHeight());  }  private boolean isOffScreenH(View descendant) {  return !isWithinDeltaOfScreenH(descendant, 0);  }  /**  * @return whether the descendant of this scroll view is within delta  *  pixels of being on the screen.  */  private boolean isWithinDeltaOfScreenV(View descendant, int delta, int height) {  descendant.getDrawingRect(mTempRect);  offsetDescendantRectToMyCoords(descendant, mTempRect);  return (mTempRect.bottom + delta) >= getScrollY()  && (mTempRect.top - delta) <= (getScrollY() + height);  }  private boolean isWithinDeltaOfScreenH(View descendant, int delta) {  descendant.getDrawingRect(mTempRect);  offsetDescendantRectToMyCoords(descendant, mTempRect);  return (mTempRect.right + delta) >= getScrollX()  && (mTempRect.left - delta) <= (getScrollX() + getWidth());  }  /**  * Smooth scroll by a Y delta  *  * @param delta the number of pixels to scroll by on the Y axis  */  private void doScrollY(int delta) {  if (delta != 0) {  if (mSmoothScrollingEnabled) {  smoothScrollBy(0, delta);  } else {  scrollBy(0, delta);  }  }  }  private void doScrollX(int delta) {  if (delta != 0) {  if (mSmoothScrollingEnabled) {  smoothScrollBy(delta, 0);  } else {  scrollBy(delta, 0);  }  }  }  /**  * Like {@link View#scrollBy}, but scroll smoothly instead of immediately.  *  * @param dx the number of pixels to scroll by on the X axis  * @param dy the number of pixels to scroll by on the Y axis  */  public void smoothScrollBy(int dx, int dy) {  if (getChildCount() == 0) {  // Nothing to do.  return;  }  long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;  if (duration > ANIMATED_SCROLL_GAP) {  final int height = getHeight() - getPaddingBottom() - getPaddingTop();  final int bottom = getChildAt(0).getHeight();  final int maxY = Math.max(0, bottom - height);  final int scrollY = getScrollY();  dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;  final int width = getWidth() - getPaddingRight() - getPaddingLeft();  final int right = getChildAt(0).getWidth();  final int maxX = Math.max(0, right - width);  final int scrollX = getScrollX();  dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX;  mScroller.startScroll(scrollX, scrollY, dx, dy);  invalidate();  } else {  if (!mScroller.isFinished()) {  mScroller.abortAnimation();  }  scrollBy(dx, dy);  }  mLastScroll = AnimationUtils.currentAnimationTimeMillis();  }  /**  * Like {@link #scrollTo}, but scroll smoothly instead of immediately.  *  * @param x the position where to scroll on the X axis  * @param y the position where to scroll on the Y axis  */  public final void smoothScrollTo(int x, int y) {  smoothScrollBy(x - getScrollX(), y - getScrollY());  }  /**  * <p>The scroll range of a scroll view is the overall height of all of its  * children.</p>  */  @Override  protected int computeVerticalScrollRange() {  final int count = getChildCount();  final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop();  if (count == 0) {  return contentHeight;  }  return getChildAt(0).getBottom();  }  @Override  protected int computeHorizontalScrollRange() {  final int count = getChildCount();  final int contentWidth = getWidth() - getPaddingLeft() - getPaddingRight();  if (count == 0) {  return contentWidth;  }  return getChildAt(0).getRight();  }  @Override  protected int computeVerticalScrollOffset() {  return Math.max(0, super.computeVerticalScrollOffset());  }  @Override  protected int computeHorizontalScrollOffset() {  return Math.max(0, super.computeHorizontalScrollOffset());  }  @Override  protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) {  int childWidthMeasureSpec;  int childHeightMeasureSpec;  childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);  childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);  child.measure(childWidthMeasureSpec, childHeightMeasureSpec);  }  @Override  protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,  int parentHeightMeasureSpec, int heightUsed) {  final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();  final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(  lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED);  final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(  lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);  child.measure(childWidthMeasureSpec, childHeightMeasureSpec);  }  @Override  public void computeScroll() {  if (mScroller.computeScrollOffset()) {  // This is called at drawing time by ViewGroup.  We don't want to  // re-show the scrollbars at this point, which scrollTo will do,  // so we replicate most of scrollTo here.  //  //         It's a little odd to call onScrollChanged from inside the drawing.  //  //         It is, except when you remember that computeScroll() is used to  //         animate scrolling. So unless we want to defer the onScrollChanged()  //         until the end of the animated scrolling, we don't really have a  //         choice here.  //  //         I agree.  The alternative, which I think would be worse, is to post  //         something and tell the subclasses later.  This is bad because there  //         will be a window where mScrollX/Y is different from what the app  //         thinks it is.  //  int x = mScroller.getCurrX();  int y = mScroller.getCurrY();  if (getChildCount() > 0) {  View child = getChildAt(0);  x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth());  y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());  super.scrollTo(x, y);  }  awakenScrollBars();  // Keep on drawing until the animation has finished.  postInvalidate();  }  }  /**  * Scrolls the view to the given child.  *  * @param child the View to scroll to  */  private void scrollToChild(View child) {  child.getDrawingRect(mTempRect);  /* Offset from child's local coordinates to ScrollView coordinates */  offsetDescendantRectToMyCoords(child, mTempRect);  int scrollDeltaV = computeScrollDeltaToGetChildRectOnScreenV(mTempRect);  int scrollDeltaH = computeScrollDeltaToGetChildRectOnScreenH(mTempRect);  if (scrollDeltaH != 0 || scrollDeltaV != 0) {  scrollBy(scrollDeltaH, scrollDeltaV);  }  }  /**  * If rect is off screen, scroll just enough to get it (or at least the  * first screen size chunk of it) on screen.  *  * @param rect      The rectangle.  * @param immediate True to scroll immediately without animation  * @return true if scrolling was performed  */  private boolean scrollToChildRect(Rect rect, boolean immediate) {  final int deltaV = computeScrollDeltaToGetChildRectOnScreenV(rect);  final int deltaH = computeScrollDeltaToGetChildRectOnScreenH(rect);  final boolean scroll = deltaH != 0 || deltaV != 0;  if (scroll) {  if (immediate) {  scrollBy(deltaH, deltaV);  } else {  smoothScrollBy(deltaH, deltaV);  }  }  return scroll;  }/**  * Compute the amount to scroll in the Y direction in order to get  * a rectangle completely on the screen (or, if taller than the screen,  * at least the first screen size chunk of it).  *  * @param rect The rect.  * @return The scroll delta.  */  protected int computeScrollDeltaToGetChildRectOnScreenV(Rect rect) {  if (getChildCount() == 0) return 0;  int height = getHeight();  int screenTop = getScrollY();  int screenBottom = screenTop + height;  int fadingEdge = getVerticalFadingEdgeLength();  // leave room for top fading edge as long as rect isn't at very top  if (rect.top > 0) {  screenTop += fadingEdge;  }  // leave room for bottom fading edge as long as rect isn't at very bottom  if (rect.bottom < getChildAt(0).getHeight()) {  screenBottom -= fadingEdge;  }  int scrollYDelta = 0;  if (rect.bottom > screenBottom && rect.top > screenTop) {  // need to move down to get it in view: move down just enough so  // that the entire rectangle is in view (or at least the first  // screen size chunk).  if (rect.height() > height) {  // just enough to get screen size chunk on  scrollYDelta += (rect.top - screenTop);  } else {  // get entire rect at bottom of screen  scrollYDelta += (rect.bottom - screenBottom);  }  // make sure we aren't scrolling beyond the end of our content  int bottom = getChildAt(0).getBottom();  int distanceToBottom = bottom - screenBottom;  scrollYDelta = Math.min(scrollYDelta, distanceToBottom);  } else if (rect.top < screenTop && rect.bottom < screenBottom) {  // need to move up to get it in view: move up just enough so that  // entire rectangle is in view (or at least the first screen  // size chunk of it).  if (rect.height() > height) {  // screen size chunk  scrollYDelta -= (screenBottom - rect.bottom);  } else {  // entire rect at top  scrollYDelta -= (screenTop - rect.top);  }  // make sure we aren't scrolling any further than the top our content  scrollYDelta = Math.max(scrollYDelta, -getScrollY());  }  return scrollYDelta;  }  protected int computeScrollDeltaToGetChildRectOnScreenH(Rect rect) {  if (getChildCount() == 0) return 0;  int width = getWidth();  int screenLeft = getScrollX();  int screenRight = screenLeft + width;  int fadingEdge = getHorizontalFadingEdgeLength();  // leave room for left fading edge as long as rect isn't at very left  if (rect.left > 0) {  screenLeft += fadingEdge;  }  // leave room for right fading edge as long as rect isn't at very right  if (rect.right < getChildAt(0).getWidth()) {  screenRight -= fadingEdge;  }  int scrollXDelta = 0;  if (rect.right > screenRight && rect.left > screenLeft) {  // need to move right to get it in view: move right just enough so  // that the entire rectangle is in view (or at least the first  // screen size chunk).  if (rect.width() > width) {  // just enough to get screen size chunk on  scrollXDelta += (rect.left - screenLeft);  } else {  // get entire rect at right of screen  scrollXDelta += (rect.right - screenRight);  }  // make sure we aren't scrolling beyond the end of our content  int right = getChildAt(0).getRight();  int distanceToRight = right - screenRight;  scrollXDelta = Math.min(scrollXDelta, distanceToRight);  } else if (rect.left < screenLeft && rect.right < screenRight) {  // need to move right to get it in view: move right just enough so that  // entire rectangle is in view (or at least the first screen  // size chunk of it).  if (rect.width() > width) {  // screen size chunk  scrollXDelta -= (screenRight - rect.right);  } else {  // entire rect at left  scrollXDelta -= (screenLeft - rect.left);  }  // make sure we aren't scrolling any further than the left our content  scrollXDelta = Math.max(scrollXDelta, -getScrollX());  }  return scrollXDelta;  }  @Override  public void requestChildFocus(View child, View focused) {  if (!mScrollViewMovedFocus) {  if (!mIsLayoutDirty) {  scrollToChild(focused);  } else {  // The child may not be laid out yet, we can't compute the scroll yet  mChildToScrollTo = focused;  }  }  super.requestChildFocus(child, focused);  }  /**  * When looking for focus in children of a scroll view, need to be a little  * more careful not to give focus to something that is scrolled off screen.  *  * This is more expensive than the default {@link android.view.ViewGroup}  * implementation, otherwise this behavior might have been made the default.  */  @Override  protected boolean onRequestFocusInDescendants(int direction,  Rect previouslyFocusedRect) {  // convert from forward / backward notation to up / down / left / right  // (ugh).  // TODO: FUCK  //        if (direction == View.FOCUS_FORWARD) {  //            direction = View.FOCUS_RIGHT;  //        } else if (direction == View.FOCUS_BACKWARD) {  //            direction = View.FOCUS_LEFT;  //        }  final View nextFocus = previouslyFocusedRect == null ?  FocusFinder.getInstance().findNextFocus(this, null, direction) :  FocusFinder.getInstance().findNextFocusFromRect(this,  previouslyFocusedRect, direction);  if (nextFocus == null) {  return false;  }  //        if (isOffScreenH(nextFocus)) {  //            return false;  //        }  return nextFocus.requestFocus(direction, previouslyFocusedRect);  }    @Override  public boolean requestChildRectangleOnScreen(View child, Rect rectangle,  boolean immediate) {  // offset into coordinate space of this scroll view  rectangle.offset(child.getLeft() - child.getScrollX(),  child.getTop() - child.getScrollY());  return scrollToChildRect(rectangle, immediate);  }  @Override  public void requestLayout() {  mIsLayoutDirty = true;  super.requestLayout();  }  @Override  protected void onLayout(boolean changed, int l, int t, int r, int b) {  super.onLayout(changed, l, t, r, b);  mIsLayoutDirty = false;  // Give a child focus if it needs it   if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {  scrollToChild(mChildToScrollTo);  }  mChildToScrollTo = null;  // Calling this with the present values causes it to re-clam them  scrollTo(getScrollX(), getScrollY());  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {  super.onSizeChanged(w, h, oldw, oldh);  View currentFocused = findFocus();  if (null == currentFocused || this == currentFocused)  return;  // If the currently-focused view was visible on the screen when the  // screen was at the old height, then scroll the screen to make that  // view visible with the new screen height.  if (isWithinDeltaOfScreenV(currentFocused, 0, oldh)) {  currentFocused.getDrawingRect(mTempRect);  offsetDescendantRectToMyCoords(currentFocused, mTempRect);  int scrollDelta = computeScrollDeltaToGetChildRectOnScreenV(mTempRect);  doScrollY(scrollDelta);  }  final int maxJump = getRight() - getLeft();  if (isWithinDeltaOfScreenH(currentFocused, maxJump)) {  currentFocused.getDrawingRect(mTempRect);  offsetDescendantRectToMyCoords(currentFocused, mTempRect);  int scrollDelta = computeScrollDeltaToGetChildRectOnScreenH(mTempRect);  doScrollX(scrollDelta);  }  }      /**  * Return true if child is an descendant of parent, (or equal to the parent).  */  private boolean isViewDescendantOf(View child, View parent) {  if (child == parent) {  return true;  }  final ViewParent theParent = child.getParent();  return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);  }      /**  * Fling the scroll view  *  * @param velocityY The initial velocity in the Y direction. Positive  *                  numbers mean that the finger/cursor is moving down the screen,  *                  which means we want to scroll towards the top.  */  public void fling(int velocityX, int velocityY) {  if (getChildCount() > 0) {  int width = getWidth() - getPaddingRight() - getPaddingLeft();  int right = getChildAt(0).getWidth();  int height = getHeight() - getPaddingBottom() - getPaddingTop();  int bottom = getChildAt(0).getHeight();  mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY,   0, Math.max(0, right - width),   0, Math.max(0, bottom - height));  //            final boolean movingDown = velocityX > 0 || velocityY > 0;  //      //            View newFocused =  //                    findFocusableViewInMyBoundsV(movingDown, mScroller.getFinalY(), findFocus());  //            if (newFocused == null) {  //                newFocused = this;  //            }  //      //            if (newFocused != findFocus()  //                    && newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : View.FOCUS_UP)) {  //                mScrollViewMovedFocus = true;  //                mScrollViewMovedFocus = false;  //            }  invalidate();  }  }  /**  * {@inheritDoc}  *  * <p>This version also clamps the scrolling to the bounds of our child.  */  @Override  public void scrollTo(int x, int y) {  // we rely on the fact the View.scrollBy calls scrollTo.  if (getChildCount() > 0) {  View child = getChildAt(0);  x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth());  y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());  if (x != getScrollX() || y != getScrollY()) {  super.scrollTo(x, y);  }  }  }  private int clamp(int n, int my, int child) {  if (my >= child || n < 0) {  /* my >= child is this case:  *                    |--------------- me ---------------|  *     |------ child ------|  * or  *     |--------------- me ---------------|  *            |------ child ------|  * or  *     |--------------- me ---------------|  *                                  |------ child ------|  *  * n < 0 is this case:  *     |------ me ------|  *                    |-------- child --------|  *     |-- mScrollX --|  */  return 0;  }  if ((my+n) > child) {  /* this case:  *                    |------ me ------|  *     |------ child ------|  *     |-- mScrollX --|  */  return child-my;  }  return n;  }  public boolean isFlingEnabled() {  return mFlingEnabled;  }  public void setFlingEnabled(boolean flingEnabled) {  this.mFlingEnabled = flingEnabled;  }  }
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