package com.martinrgb.animer.component.scrollview;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.os.Build;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.Log;
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.ViewDebug;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.animation.AnimationUtils;
import android.widget.FrameLayout;

import com.martinrgb.animer.Animer;

import java.util.List;

public class AnScrollView extends FrameLayout {
    static final int ANIMATED_SCROLL_GAP = 500;

    static final float MAX_SCROLL_FACTOR = 0.5f;

    // clampedY 回弹 init is 0.25f; // 0.4
    static final float FOLLOW_HAND_FACTOR = 0.25f; //0.25f

    private static final String TAG = "ScrollView";

    private long mLastScroll;

    private final Rect mTempRect = new Rect();
    public AnOverScroller mScroller;

    /**
     * Position of the last motion event.
     */
    private int mLastMotionY;
    private int 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.
     */
    @ViewDebug.ExportedProperty(category = "layout")
    private boolean mFillViewport;

    /**
     * Whether arrow scrolling is animated.
     */
    private boolean mSmoothScrollingEnabled = true;

    private int mTouchSlop;
    private int mMinimumVelocity;
    private int mMaximumVelocity;

    private int mOverscrollDistance;
    private int mOverflingDistance;

    /**
     * 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 SavedState mSavedState;

    public AnScrollView(Context context) {
        this(context, null);
    }

    public AnScrollView(Context context, AttributeSet attrs) {
        this(context, attrs, 0); //TODO: com.android.internal.R.attr.scrollViewStyle);
    }

    public AnScrollView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initScrollView();
    }

    @Override
    public int getOverScrollMode() {
        return OVER_SCROLL_ALWAYS;
    }

    @Override
    public boolean shouldDelayChildPressedState() {
        return true;
    }

    @Override
    protected float getTopFadingEdgeStrength() {
        return 0;
    }

    @Override
    protected float getBottomFadingEdgeStrength() {
        return 0;
    }

    /**
     * @return The maximum amount this scroll view will scroll in response to
     *   an arrow event.
     */
    public int getMaxScrollAmount() {
        return (int) (MAX_SCROLL_FACTOR * (getBottom() - getTop()));
    }


    private void initScrollView() {
        mScroller = new AnOverScroller(getContext());
        //mScroller.setVertScroll(isVertScroll());
        setFocusable(true);
        setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
        setWillNotDraw(false);
        final ViewConfiguration configuration = ViewConfiguration.get(getContext());
        mTouchSlop = configuration.getScaledTouchSlop();
        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
        mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
        mOverscrollDistance = configuration.getScaledOverscrollDistance();
        mOverflingDistance = configuration.getScaledOverflingDistance();
    }

    @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 canScroll() {
        View child = getChildAt(0);
        if (child != null) {
            if(isVertScroll()){
                int childHeight = child.getHeight();
                return getHeight() < childHeight + getPaddingTop() + getPaddingBottom();
            }
            else{
                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.
     *
     * @attr ref android.R.styleable#ScrollView_fillViewport
     */
    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.
     *
     * @attr ref android.R.styleable#ScrollView_fillViewport
     */
    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);
        if (heightMode == MeasureSpec.UNSPECIFIED) {
            return;
        }
        Log.e("totalHeight",String.valueOf(heightMeasureSpec));

        if (getChildCount() > 0) {
            final View child = getChildAt(0);
            int height = getMeasuredHeight();
            int width = getMeasuredWidth();
            if(isVertScroll()) {
                if (child.getMeasuredHeight() < height) {
                    final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams();

                    int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
                            getPaddingLeft() + getPaddingRight(), lp.width);
                    height -= getPaddingTop();
                    height -= getPaddingBottom();
                    int childHeightMeasureSpec =
                            MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);

                    child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
                }
            }else{
                if (child.getMeasuredWidth() < width) {
                    final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams();

                    int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec,
                            getPaddingTop() + getPaddingBottom(), lp.height);
                    width -= getPaddingLeft();
                    width -= getPaddingRight();
                    int childWidthMeasureSpec =
                            MeasureSpec.makeMeasureSpec(width, 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();

        if (!canScroll()) {
            if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) {
                View currentFocused = findFocus();
                if (currentFocused == this) currentFocused = null;
                View nextFocused = FocusFinder.getInstance().findNextFocus(this,
                        currentFocused, View.FOCUS_DOWN);
                return nextFocused != null
                        && nextFocused != this
                        && nextFocused.requestFocus(View.FOCUS_DOWN);
            }
            return false;
        }

        boolean handled = false;
        if (event.getAction() == KeyEvent.ACTION_DOWN) {
            switch (event.getKeyCode()) {
                case KeyEvent.KEYCODE_DPAD_UP:
                    if (!event.isAltPressed()) {
                        handled = arrowScroll(View.FOCUS_UP);
                    } else {
                        handled = fullScroll(View.FOCUS_UP);
                    }
                    break;
                case KeyEvent.KEYCODE_DPAD_DOWN:
                    if (!event.isAltPressed()) {
                        handled = arrowScroll(View.FOCUS_DOWN);
                    } else {
                        handled = fullScroll(View.FOCUS_DOWN);
                    }
                    break;
                case KeyEvent.KEYCODE_SPACE:
                    pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN);
                    break;
            }
        }

        return handled;
    }

    private boolean inChild(int x, int y) {
        if (getChildCount() > 0) {
            final int scrollY = getScrollY();
            final int scrollX = getScrollX();
            final View child = getChildAt(0);
            if(isVertScroll()){
                return !(y < child.getTop() - scrollY
                        || y >= child.getBottom() - scrollY
                        || x < child.getLeft()
                        || x >= child.getRight());
            }
            else {
                return !(y < child.getTop()
                        || y >= child.getBottom()
                        || x < child.getLeft() - scrollX
                        || x >= child.getRight() - scrollX);
            }

        }
        return false;
    }

    private void initOrResetVelocityTracker() {
        if (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        } else {
            mVelocityTracker.clear();
        }
    }

    private void initVelocityTrackerIfNotExists() {
        if (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        }
    }

    private void recycleVelocityTracker() {
        if (mVelocityTracker != null) {
            mVelocityTracker.recycle();
            mVelocityTracker = null;
        }
    }

    @Override
    public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
        if (disallowIntercept) {
            recycleVelocityTracker();
        }
        super.requestDisallowInterceptTouchEvent(disallowIntercept);
    }


    @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;
        }

        /*
         * Don't try to intercept touch if we can't scroll anyway.
         */
        if (getScrollY() == 0 && !canScrollVertically(1) && isVertScroll()) {
            return false;
        }

        if (getScrollX() == 0 && !canScrollVertically(1) && !isVertScroll()) {
            return false;
        }

        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);
                if (pointerIndex == -1) {
                    Log.e(TAG, "Invalid pointerId=" + activePointerId
                            + " in onInterceptTouchEvent");
                    break;
                }

                if(isVertScroll()) {
                    final int y = (int) ev.getY(pointerIndex);
                    final int yDiff = Math.abs(y - mLastMotionY);
                    if (yDiff > mTouchSlop) {
                        mIsBeingDragged = true;
                        mLastMotionY = y;
                        initVelocityTrackerIfNotExists();
                        mVelocityTracker.addMovement(ev);
                        final ViewParent parent = getParent();
                        if (parent != null) {
                            parent.requestDisallowInterceptTouchEvent(true);
                        }
                    }
                }
                else{
                    final int x = (int) ev.getX(pointerIndex);
                    final int xDiff = Math.abs(x - mLastMotionX);
                    if (xDiff > mTouchSlop) {
                        mIsBeingDragged = true;
                        mLastMotionX = x;
                        initVelocityTrackerIfNotExists();
                        mVelocityTracker.addMovement(ev);
                        final ViewParent parent = getParent();
                        if (parent != null) {
                            parent.requestDisallowInterceptTouchEvent(true);
                        }
                    }
                }
                break;
            }

            case MotionEvent.ACTION_DOWN: {
                if(isVertScroll()) {
                    final int y = (int) ev.getY();
                    if (!inChild((int) ev.getX(), (int) y)) {
                        mIsBeingDragged = false;
                        recycleVelocityTracker();
                        break;
                    }

                    /*
                     * Remember location of down touch.
                     * ACTION_DOWN always refers to pointer index 0.
                     */
                    mLastMotionY = y;
                }
                else{
                    final int x = (int) ev.getX();
                    if (!inChild((int) x, (int) ev.getY())) {
                        mIsBeingDragged = false;
                        recycleVelocityTracker();
                        break;
                    }

                    /*
                     * Remember location of down touch.
                     * ACTION_DOWN always refers to pointer index 0.
                     */
                    mLastMotionX = x;
                }


                mActivePointerId = ev.getPointerId(0);

                initOrResetVelocityTracker();
                mVelocityTracker.addMovement(ev);
                /*
                 * 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;
                recycleVelocityTracker();
                if(isVertScroll()){
                    if (mScroller.springBack(getScrollX(), getScrollY(), 0,0,0, 0, 0, getScrollRange())) {
                        postInvalidateOnAnimation();
                    }
                }
                else {
                    if (mScroller.springBack(getScrollX(), getScrollY(), 0,0,0, getScrollRange(), 0, 0)) {
                        postInvalidateOnAnimation();
                    }
                }


                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) {
        initVelocityTrackerIfNotExists();
        mVelocityTracker.addMovement(ev);

        final int action = ev.getAction();

        switch (action & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN: {
                if (getChildCount() == 0) {
                    return false;
                }
                if ((mIsBeingDragged = !mScroller.isFinished())) {
                    final ViewParent parent = getParent();
                    if (parent != null) {
                        parent.requestDisallowInterceptTouchEvent(true);
                    }
                }

                /*
                 * 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
                if(isVertScroll()){
                    mLastMotionY = (int) ev.getY();
                }
                else {
                    mLastMotionX = (int) ev.getX();
                }

                mActivePointerId = ev.getPointerId(0);
                break;
            }
            case MotionEvent.ACTION_MOVE:
                final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
                if (activePointerIndex == -1) {
                    Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent");
                    break;
                }

                if(isVertScroll()) {
                    final int y = (int) ev.getY(activePointerIndex);
                    int deltaY = mLastMotionY - y;
                    if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) {
                        final ViewParent parent = getParent();
                        if (parent != null) {
                            parent.requestDisallowInterceptTouchEvent(true);
                        }
                        mIsBeingDragged = true;
                        if (deltaY > 0) {
                            deltaY -= mTouchSlop;
                        } else {
                            deltaY += mTouchSlop;
                        }
                    }
                    if (mIsBeingDragged) {
                        // Scroll to follow the motion event
                        mLastMotionY = y;

                        final int oldX = getScrollX();
                        final int oldY = getScrollY();
                        final int range = getScrollRange();
                        final int overscrollMode = getOverScrollMode();
                        final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS ||
                                (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);

                        // Calling overScrollBy will call onOverScrolled, which
                        // calls onScrollChanged if applicable.
                        if (overScrollBy(0, deltaY, 0, getScrollY(),
                                0, range, 0, mOverscrollDistance, true)) {
                            // Break our velocity if we hit a scroll barrier.
                            mVelocityTracker.clear();
                        }
                    }
                }
                else{
                    final int x = (int) ev.getX(activePointerIndex);
                    int deltaX = mLastMotionX - x;
                    if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) {
                        final ViewParent parent = getParent();
                        if (parent != null) {
                            parent.requestDisallowInterceptTouchEvent(true);
                        }
                        mIsBeingDragged = true;
                        if (deltaX > 0) {
                            deltaX -= mTouchSlop;
                        } else {
                            deltaX += mTouchSlop;
                        }
                    }
                    if (mIsBeingDragged) {
                        // Scroll to follow the motion event
                        mLastMotionX = x;

                        final int oldX = getScrollX();
                        final int oldY = getScrollY();
                        final int range = getScrollRange();
                        final int overscrollMode = getOverScrollMode();
                        final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS ||
                                (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);

                        // Calling overScrollBy will call onOverScrolled, which
                        // calls onScrollChanged if applicable.
                        if (overScrollBy(deltaX, 0, getScrollX(), 0,
                                range, 0, mOverscrollDistance, 0, true)) {
                            // Break our velocity if we hit a scroll barrier.
                            mVelocityTracker.clear();
                        }
                    }
                }
                break;
            case MotionEvent.ACTION_UP:
                if (mIsBeingDragged) {
                    final VelocityTracker velocityTracker = mVelocityTracker;
                    velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
                    int initialVelocityY = (int) velocityTracker.getYVelocity(mActivePointerId);
                    int initialVelocityX =  (int) velocityTracker.getXVelocity(mActivePointerId);

                    if (getChildCount() > 0) {
                        if(isVertScroll()) {
                            if ((Math.abs(initialVelocityY) > mMinimumVelocity)) {
                                fling(-initialVelocityY);
                            } else {
                                if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, 0, 0, getScrollRange())) {
                                    postInvalidateOnAnimation();
                                }
                            }
                        }
                        else {
                            if ((Math.abs(initialVelocityX) > mMinimumVelocity)) {
                                fling(-initialVelocityX);
                            } else{
                                if (mScroller.springBack(getScrollX(), getScrollY(),0,0, 0, getScrollRange(), 0, 0)) {
                                    postInvalidateOnAnimation();
                                }
                            }
                        }
                    }

                    mActivePointerId = INVALID_POINTER;
                    endDrag();
                }
                break;
            case MotionEvent.ACTION_CANCEL:
                if (mIsBeingDragged && getChildCount() > 0) {
                    if(isVertScroll()){
                        if (mScroller.springBack(getScrollX(), getScrollY(),0,0, 0, 0, 0, getScrollRange())) {
                            postInvalidateOnAnimation();
                        }
                    }
                    else {
                        if (mScroller.springBack(getScrollX(), getScrollY(),0,0, 0, getScrollRange(), 0, 0)) {
                            postInvalidateOnAnimation();
                        }
                    }
                    mActivePointerId = INVALID_POINTER;
                    endDrag();
                }
                break;
            case MotionEvent.ACTION_POINTER_DOWN: {
                final int index = ev.getActionIndex();
                if(isVertScroll()){
                    mLastMotionY = (int) ev.getY(index);
                }
                else {
                    mLastMotionX = (int) ev.getX(index);
                }

                mActivePointerId = ev.getPointerId(index);
                break;
            }
            case MotionEvent.ACTION_POINTER_UP:
                onSecondaryPointerUp(ev);
                if(isVertScroll()){
                    mLastMotionY = (int) ev.getY(ev.findPointerIndex(mActivePointerId));
                }
                else {
                    mLastMotionY = (int) ev.getX(ev.findPointerIndex(mActivePointerId));
                }

                break;
        }
        return true;
    }

    private void onSecondaryPointerUp(MotionEvent ev) {
        final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
                MotionEvent.ACTION_POINTER_INDEX_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.
            // TODO: Make this decision more intelligent.
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
            if(isVertScroll()){
                mLastMotionY = (int) ev.getY(newPointerIndex);
            }
            else {
                mLastMotionX = (int) ev.getX(newPointerIndex);
            }
            mActivePointerId = ev.getPointerId(newPointerIndex);
            if (mVelocityTracker != null) {
                mVelocityTracker.clear();
            }
        }
    }

//  @Override
//  public boolean onGenericMotionEvent(MotionEvent event) {
//    if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) {
//      switch (event.getAction()) {
//        case MotionEvent.ACTION_SCROLL: {
//          if (!mIsBeingDragged) {
//            final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL);
//            if (vscroll != 0) {
//              final int delta = (int) (vscroll * getVerticalScrollFactor());
//              final int range = getScrollRange();
//              int oldScrollY = getScrollY();
//              int newScrollY = oldScrollY - delta;
//              if (newScrollY < 0) {
//                newScrollY = 0;
//              } else if (newScrollY > range) {
//                newScrollY = range;
//              }
//              if (newScrollY != oldScrollY) {
//                super.scrollTo(getScrollX(), newScrollY);
//                return true;
//              }
//            }
//          }
//        }
//      }
//    }
//    return super.onGenericMotionEvent(event);
//  }

    // 滑动后的松手

    @Override
    protected void onOverScrolled(int scrollX, int scrollY,
                                  boolean clampedX, boolean clampedY) {
        // Treat animating scrolls differently; see #computeScroll() for why.
        if (!mScroller.isFinished()) {
            final int oldX = getScrollX();
            final int oldY = getScrollY();
            setScrollX(scrollX);
            setScrollY(scrollY);
            invalidateParentIfNeeded();
            onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);

            if(isVertScroll()){
                if (clampedY) {
                    //松手后 OverScroll 的滑动
                    mScroller.springBack(getScrollX(), getScrollY(), 0,0,0, 0, 0, getScrollRange());
                }
            }
            else {
                if(clampedX){
                    mScroller.springBack(getScrollX(), getScrollY(), 0,0,0, getScrollRange(), 0, 0);
                }
            }


        } else {
            //跟手的滑动(包括 OverScroll)
            super.scrollTo(scrollX, scrollY);

        }

        awakenScrollBars();
    }

    private void invalidateParentIfNeeded() {

        if (isHardwareAccelerated() && getParent() instanceof View) {
            ((View) getParent()).invalidate();
        }
    }

    @Override
    public boolean performAccessibilityAction(int action, Bundle arguments) {
        if (super.performAccessibilityAction(action, arguments)) {
            return true;
        }
        if (!isEnabled()) {
            return false;
        }
        switch (action) {
            case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: {
                if(isVertScroll()){
                    final int viewportHeight = getHeight() - getPaddingBottom() - getPaddingTop();
                    final int targetScrollY = Math.min(getScrollY() + viewportHeight, getScrollRange());
                    if (targetScrollY != getScrollY()) {
                        smoothScrollTo(0, targetScrollY);
                        return true;
                    }
                }
                else {
                    final int viewportWidth = getWidth() - getPaddingRight() - getPaddingLeft();
                    final int targetScrollX = Math.min(getScrollX() + viewportWidth, getScrollRange());
                    if (targetScrollX != getScrollX()) {
                        smoothScrollTo(targetScrollX, 0);
                        return true;
                    }
                }

            } return false;
            case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: {
                if(isVertScroll()){
                    final int viewportHeight = getHeight() - getPaddingBottom() - getPaddingTop();
                    final int targetScrollY = Math.max(getScrollY() - viewportHeight, 0);
                    if (targetScrollY != getScrollY()) {
                        smoothScrollTo(0, targetScrollY);
                        return true;
                    }
                }
                else {
                    final int viewportWidth = getWidth() - getPaddingRight() - getPaddingLeft();
                    final int targetScrollX = Math.max(getScrollX() - viewportWidth, 0);
                    if (targetScrollX != getScrollX()) {
                        smoothScrollTo(targetScrollX, 0);
                        return true;
                    }
                }

            } return false;
        }
        return false;
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        info.setClassName(AnScrollView.class.getName());
        if (isEnabled()) {
            final int scrollRange = getScrollRange();
            if (scrollRange > 0) {
                info.setScrollable(true);
                if(isVertScroll()){
                    if (getScrollY() > 0) {
                        info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD);
                    }
                    if (getScrollY() < scrollRange) {
                        info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD);
                    }
                }
                else {
                    if (getScrollX() > 0) {
                        info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD);
                    }
                    if (getScrollX() < scrollRange) {
                        info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD);
                    }
                }

            }
        }
    }

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        event.setClassName(AnScrollView.class.getName());
        final boolean scrollable = getScrollRange() > 0;
        event.setScrollable(scrollable);
        event.setScrollX(getScrollX());
        event.setScrollY(getScrollY());
        if(isVertScroll()){
            event.setMaxScrollX(getScrollX());
            event.setMaxScrollY(getScrollRange());
        }
        else {
            event.setMaxScrollX(getScrollRange());
            event.setMaxScrollY(getScrollY());
        }

    }

    private int getScrollRange() {
        int scrollRange = 0;
        if (getChildCount() > 0) {
            View child = getChildAt(0);
            if(isVertScroll()){
                scrollRange = Math.max(0,child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop()));
            }
            else {
                scrollRange = Math.max(0,child.getWidth() - (getWidth() - getPaddingLeft() - getPaddingRight()));
            }
        }
        return scrollRange;
    }

    /**
     * <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 findFocusableViewInBounds(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();
        if(isVertScroll()){
            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;
                            }
                        }
                    }
                }
            }
        }
        else {
            for (int i = 0; i < count; i++) {
                View view = focusables.get(i);
                int viewLeft = view.getLeft();
                int viewRight = view.getRight();

                if (top < viewRight && viewLeft < bottom) {
                    /*
                     * the focusable is in the target area, it is a candidate for
                     * focusing
                     */

                    final boolean viewIsFullyContained = (top < viewLeft) &&
                            (viewRight < bottom);

                    if (focusCandidate == null) {
                        /* No candidate, take this one */
                        focusCandidate = view;
                        foundFullyContainedFocusable = viewIsFullyContained;
                    } else {
                        final boolean viewIsCloserToBoundary =
                                (topFocus && viewLeft < focusCandidate.getLeft()) ||
                                        (!topFocus && 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 "page up/down" shortcut press. This
     * method will scroll the view by one page up or down 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 one page up or
     *                  {@link android.view.View#FOCUS_DOWN} to go one page down
     * @return true if the key event is consumed by this method, false otherwise
     */
    public boolean pageScroll(int direction) {
        boolean down = direction == View.FOCUS_DOWN;
        if(isVertScroll()) {
            int height = getHeight();

            if (down) {
                mTempRect.top = getScrollY() + height;
                int count = getChildCount();
                if (count > 0) {
                    View view = getChildAt(count - 1);
                    if (mTempRect.top + height > view.getBottom()) {
                        mTempRect.top = view.getBottom() - height;
                    }
                }
            } else {
                mTempRect.top = getScrollY() - height;
                if (mTempRect.top < 0) {
                    mTempRect.top = 0;
                }
            }
            mTempRect.bottom = mTempRect.top + height;

            return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
        }
        else{
            int width = getWidth();

            if (down) {
                mTempRect.left = getScrollX() + width;
                int count = getChildCount();
                if (count > 0) {
                    View view = getChildAt(count - 1);
                    if (mTempRect.left + width > view.getRight()) {
                        mTempRect.left = view.getRight() - width;
                    }
                }
            } else {
                mTempRect.left = getScrollX() - width;
                if (mTempRect.left < 0) {
                    mTempRect.left = 0;
                }
            }
            mTempRect.right = mTempRect.left + width;

            return scrollAndFocus(direction, mTempRect.left,mTempRect.right);
        }
    }

    /**
     * <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 fullScroll(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() + getPaddingBottom();
                mTempRect.top = mTempRect.bottom - height;
            }
        }

        return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
    }

    /**
     * <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 scrollAndFocus(int direction, int top, int bottom) {
        boolean handled = true;

        if(isVertScroll()){
            int height = getHeight();
            int containerTop = getScrollY();
            int containerBottom = containerTop + height;
            boolean up = direction == View.FOCUS_UP;

            View newFocused = findFocusableViewInBounds(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);
        }
        else {
            int width = getWidth();
            int containerLeft = getScrollX();
            int containerRight = containerLeft + width;
            boolean up = direction == View.FOCUS_UP;

            View newFocused = findFocusableViewInBounds(up, top, bottom);
            if (newFocused == null) {
                newFocused = this;
            }

            if (top >= containerLeft && bottom <= containerRight) {
                handled = false;
            } else {
                int delta = up ? (top - containerLeft) : (bottom - containerRight);
                doScrollX(delta);
            }

            if (newFocused != findFocus()) newFocused.requestFocus(direction);
        }


        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 arrowScroll(int direction) {

        View currentFocused = findFocus();
        if (currentFocused == this) currentFocused = null;

        View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);

        final int maxJump = getMaxScrollAmount();

        if(isVertScroll()){
            if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) {
                nextFocused.getDrawingRect(mTempRect);
                offsetDescendantRectToMyCoords(nextFocused, mTempRect);
                int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(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() - getPaddingBottom();
                        if (daBottom - screenBottom < maxJump) {
                            scrollDelta = daBottom - screenBottom;
                        }
                    }
                }
                if (scrollDelta == 0) {
                    return false;
                }
                doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
            }
        }
        else {
            if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getWidth())) {
                nextFocused.getDrawingRect(mTempRect);
                offsetDescendantRectToMyCoords(nextFocused, mTempRect);
                int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
                doScrollX(scrollDelta);
                nextFocused.requestFocus(direction);
            } else {
                // no new focus
                int scrollDelta = maxJump;

                if (direction == View.FOCUS_UP && getScrollX() < scrollDelta) {
                    scrollDelta = getScrollX();
                } else if (direction == View.FOCUS_DOWN) {
                    if (getChildCount() > 0) {
                        int daRight = getChildAt(0).getRight();
                        int screenRight = getScrollX() + getWidth() - getPaddingRight();
                        if (daRight - screenRight < maxJump) {
                            scrollDelta = daRight - screenRight;
                        }
                    }
                }
                if (scrollDelta == 0) {
                    return false;
                }
                doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
            }
        }


        if (currentFocused != null && currentFocused.isFocused()
                && isOffScreen(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 isOffScreen(View descendant) {
        if(isVertScroll()){
            return !isWithinDeltaOfScreen(descendant, 0, getHeight());
        }
        else {
            return !isWithinDeltaOfScreen(descendant, 0, getWidth());
        }

    }

    /**
     * @return whether the descendant of this scroll view is within delta
     *  pixels of being on the screen.
     */
    private boolean isWithinDeltaOfScreen(View descendant, int delta, int value) {
        descendant.getDrawingRect(mTempRect);
        offsetDescendantRectToMyCoords(descendant, mTempRect);

        if(isVertScroll()){
            return (mTempRect.bottom + delta) >= getScrollY()  && (mTempRect.top - delta) <= (getScrollY() + value);
        }
        else {
            return (mTempRect.right + delta) >= getScrollX()  && (mTempRect.left - delta) <= (getScrollX() + value);
        }
    }

    /**
     * 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 final void smoothScrollBy(int dx, int dy) {
        if (getChildCount() == 0) {
            // Nothing to do.
            return;
        }
        long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
        if (duration > ANIMATED_SCROLL_GAP) {
            if(isVertScroll()){
                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;

                mScroller.startScroll(getScrollX(), scrollY, 0, dy);
            }
            else {
                final int width = getWidth() - getPaddingRight() - getPaddingLeft();
                final int right = getChildAt(0).getRight();
                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, getScrollY(), dx, 0);
            }

            postInvalidateOnAnimation();
        } 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();
        final int contentWidth = getWidth() - getPaddingRight() - getPaddingLeft();
        if(isVertScroll()){
            if (count == 0) {
                return contentHeight;
            }
        }
        else {
            if (count == 0) {
                return contentWidth;
            }
        }


        if(isVertScroll()){
            int scrollRange = getChildAt(0).getBottom();
            final int scrollY = getScrollY();
            final int overscrollBottom = Math.max(0, scrollRange - contentHeight);
            if (scrollY < 0) {
                scrollRange -= scrollY;
            } else if (scrollY > overscrollBottom) {
                scrollRange += scrollY - overscrollBottom;
            }

            return scrollRange;
        }
        else {
            int scrollRange = getChildAt(0).getRight();
            final int scrollX = getScrollX();
            final int overscrollRight = Math.max(0, scrollRange - contentWidth);
            if (scrollX < 0) {
                scrollRange -= scrollX;
            } else if (scrollX > overscrollRight) {
                scrollRange += scrollX - overscrollRight;
            }

            return scrollRange;
        }
    }

    @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) {
        ViewGroup.LayoutParams lp = child.getLayoutParams();

        int childWidthMeasureSpec;
        int childHeightMeasureSpec;

        if(isVertScroll()){
            childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft()
                    + getPaddingRight(), lp.width);

            childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        }
        else {
            childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, getPaddingTop()
                    + getPaddingBottom(), lp.height);
            childWidthMeasureSpec = 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();

        int childWidthMeasureSpec;
        int childHeightMeasureSpec;
        if (isVertScroll()) {
            childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
                    getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin
                            + widthUsed, lp.width);
             childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
                    lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);
        }
        else {
            childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
                    getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin
                            + heightUsed, lp.height);
            childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
                    lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED);
        }


        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
    }

    @Override
    public void computeScroll() {
        //滚动尚未完成
        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 getScrollX()/Y is different from what the app
            //         thinks it is.
            //
            int oldX = getScrollX();
            int oldY = getScrollY();
            int x = mScroller.getCurrX();
            int y = mScroller.getCurrY();


            if (oldX != x || oldY != y) {
                final int range = getScrollRange();
                final int overscrollMode = getOverScrollMode();
                final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS ||
                        (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);

                if(isVertScroll()){
                    overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, range,
                            0, mOverflingDistance, false);
                }else {
                    overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0,
                            mOverflingDistance,0, false);
                }

                onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);
            }

            if (!awakenScrollBars()) {
                // Keep on drawing until the animation has finished.
                postInvalidateOnAnimation();
            }
        }
    }

    /**
     * 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 scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);

        if (scrollDelta != 0) {
            if(isVertScroll()){
                scrollBy(0, scrollDelta);
            }
            else {
                scrollBy(scrollDelta, 0);
            }
        }
    }

    /**
     * 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 delta = computeScrollDeltaToGetChildRectOnScreen(rect);
        final boolean scroll = delta != 0;
        if (scroll) {
            if (immediate) {
                if(isVertScroll()){
                    scrollBy(0, delta);
                }
                else {
                    scrollBy(delta, 0);
                }
            } else {
                if(isVertScroll()){
                    smoothScrollBy(0, delta);
                }
                else {
                    smoothScrollBy(delta, 0);
                }
            }
        }
        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 computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
        if (getChildCount() == 0) return 0;

        int height = getHeight();
        int screenTop = getScrollY();
        int screenBottom = screenTop + height;

        int width = getWidth();
        int screenLeft = getScrollX();
        int screenRight = screenLeft + width;

        int fadingEdgeVertical = getVerticalFadingEdgeLength();
        int fadingEdgeHorizontal = getHorizontalFadingEdgeLength();

        if(isVertScroll()){
            // leave room for top fading edge as long as rect isn't at very top
            if (rect.top > 0) {
                screenTop += fadingEdgeVertical;
            }

            // leave room for bottom fading edge as long as rect isn't at very bottom
            if (rect.bottom < getChildAt(0).getHeight()) {
                screenBottom -= fadingEdgeVertical;
            }

            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;

        }else {
            // leave room for top fading edge as long as rect isn't at very top
            if (rect.left > 0) {
                screenLeft += fadingEdgeHorizontal;
            }

            // leave room for bottom fading edge as long as rect isn't at very bottom
            if (rect.right < getChildAt(0).getWidth()) {
                screenRight -= fadingEdgeHorizontal;
            }

            int scrollXDelta = 0;

            if (rect.right > screenRight && rect.left > screenLeft) {
                // 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.width() > width) {
                    // just enough to get screen size chunk on
                    scrollXDelta += (rect.left - screenLeft);
                } else {
                    // get entire rect at bottom 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 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.width() > width) {
                    // screen size chunk
                    scrollXDelta -= (screenRight - rect.right);
                } else {
                    // entire rect at top
                    scrollXDelta -= (screenLeft - rect.left);
                }

                // make sure we aren't scrolling any further than the top our content
                scrollXDelta = Math.max(scrollXDelta, -getScrollX());
            }
            return scrollXDelta;
        }

    }

    @Override
    public void requestChildFocus(View child, View focused) {
        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).
        if (direction == View.FOCUS_FORWARD) {
            direction = View.FOCUS_DOWN;
        } else if (direction == View.FOCUS_BACKWARD) {
            direction = View.FOCUS_UP;
        }

        final View nextFocus = previouslyFocusedRect == null ?
                FocusFinder.getInstance().findNextFocus(this, null, direction) :
                FocusFinder.getInstance().findNextFocusFromRect(this,
                        previouslyFocusedRect, direction);

        if (nextFocus == null) {
            return false;
        }

        if (isOffScreen(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 onDetachedFromWindow() {
        super.onDetachedFromWindow();
    }

    @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;

        if (!isLaidOut()) {
            if (mSavedState != null) {
                if(isVertScroll()){
                    setScrollY(mSavedState.scrollPosition);
                }
                else {
                    setScrollX(mSavedState.scrollPosition);
                }
                mSavedState = null;
            } // getScrollY() default value is "0"

            final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0;
            final int scrollRangeY = Math.max(0, childHeight - (b - t - getPaddingBottom() - getPaddingTop()));

            final int childWidth = (getChildCount() > 0) ? getChildAt(0).getMeasuredWidth() : 0;
            final int scrollRangeX = Math.max(0, childWidth - (r - l - getPaddingRight() - getPaddingLeft()));

            if(isVertScroll()){
                // Don't forget to clamp
                if (getScrollY() > scrollRangeY) {
                    setScrollY(scrollRangeY);
                } else if (getScrollY() < 0) {
                    //Original is setScaleY
                    setScrollY(0);
                }
            }
            else {
                // Don't forget to clamp
                if (getScrollX() > scrollRangeX) {
                    setScrollX(scrollRangeX);
                } else if (getScrollX() < 0) {
                    setScrollX(0);
                }
            }

        }

        // Calling this with the present values causes it to re-claim 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(isVertScroll()){
            if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {
                currentFocused.getDrawingRect(mTempRect);
                offsetDescendantRectToMyCoords(currentFocused, mTempRect);
                int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
                doScrollY(scrollDelta);
            }
        }
        else {
            if (isWithinDeltaOfScreen(currentFocused, 0, oldw)) {
                currentFocused.getDrawingRect(mTempRect);
                offsetDescendantRectToMyCoords(currentFocused, mTempRect);
                int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
                doScrollX(scrollDelta);
            }
        }

    }

    /**
     * Return true if child is a descendant of parent, (or equal to the parent).
     */
    private static 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 velocity 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 velocity) {
        if (getChildCount() > 0) {
            int height = getHeight() - getPaddingBottom() - getPaddingTop();
            int bottom = getChildAt(0).getHeight();
            int width = getWidth() - getPaddingRight() - getPaddingLeft();
            int right = getChildAt(0).getRight();
            if(isVertScroll()) {
                mScroller.fling(getScrollX(), getScrollY(), 0, velocity, 0, 0, 0,
                        Math.max(0, bottom - height), 0, height / 2);
            }
            else {
                mScroller.fling(getScrollX(), getScrollY(), velocity, 0, 0, Math.max(0, right - width), 0,
                        0, width/2, 0);
            }
            postInvalidateOnAnimation();
        }
    }


    private void endDrag() {
        mIsBeingDragged = false;
        recycleVelocityTracker();
    }

    /**
     * {@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) {
            if (x != getScrollX() || y != getScrollY()) {
                super.scrollTo(x, y);
            }
        }
    }

    @Override
    public void setOverScrollMode(int mode) {
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (getContext().getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) {
            // Some old apps reused IDs in ways they shouldn't have.
            // Don't break them, but they don't get scroll state restoration.
            super.onRestoreInstanceState(state);
            return;
        }
        SavedState ss = (SavedState) state;
        super.onRestoreInstanceState(ss.getSuperState());
        mSavedState = ss;
        requestLayout();
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        if (getContext().getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) {
            // Some old apps reused IDs in ways they shouldn't have.
            // Don't break them, but they don't get scroll state restoration.
            return super.onSaveInstanceState();
        }
        Parcelable superState = super.onSaveInstanceState();
        SavedState ss = new SavedState(superState);
        ss.scrollPosition = getScrollY();
        return ss;
    }

    static class SavedState extends BaseSavedState {
        public int scrollPosition;

        SavedState(Parcelable superState) {
            super(superState);
        }

        public SavedState(Parcel source) {
            super(source);
            scrollPosition = source.readInt();
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            dest.writeInt(scrollPosition);
        }

        @Override
        public String toString() {
            return "HorizontalScrollView.SavedState{"
                    + Integer.toHexString(System.identityHashCode(this))
                    + " scrollPosition=" + scrollPosition + "}";
        }

        public static final Parcelable.Creator<SavedState> CREATOR
                = new Parcelable.Creator<SavedState>() {
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in);
            }

            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }


    protected boolean overScrollBy(int deltaX, int deltaY,
                                   int scrollX, int scrollY,
                                   int scrollRangeX, int scrollRangeY,
                                   int maxOverScrollX, int maxOverScrollY,
                                   boolean isTouchEvent) {
        final int overScrollMode = OVER_SCROLL_ALWAYS;
        final boolean canScrollHorizontal =
                computeHorizontalScrollRange() > computeHorizontalScrollExtent();
        final boolean canScrollVertical =
                computeVerticalScrollRange() > computeVerticalScrollExtent();
        final boolean overScrollHorizontal = overScrollMode == OVER_SCROLL_ALWAYS ||
                (overScrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal);
        final boolean overScrollVertical = overScrollMode == OVER_SCROLL_ALWAYS ||
                (overScrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical);

        //  不涉及 Drag + Overscroll 的 Fling
        int newScrollX = scrollX + deltaX;
        if (!overScrollHorizontal) {
          maxOverScrollX = 0;
        }

        int newScrollY = scrollY + deltaY;
        if (!overScrollVertical) {
            maxOverScrollY = 0;
        }

        // Clamp values if at the limits and record
        int padding = 0;
        final int left = -maxOverScrollX - padding;
        final int right = maxOverScrollX + scrollRangeX + padding;
        final int top = -maxOverScrollY - padding;
        final int bottom = maxOverScrollY + scrollRangeY + padding;

        boolean clampedX = false;
        if (newScrollX > right) {
            //newScrollX = right;
            clampedX = true;
        } else if (newScrollX < left) {
            //newScrollX = left;
            clampedX = true;
        }

        boolean clampedY = false;
        if (newScrollY > bottom) {
            //newScrollY = bottom;
            clampedY = true;
        } else if (newScrollY < top) {
            //newScrollY = top;
            clampedY = true;
        }

        if (mIsBeingDragged && clampedX) {
            newScrollX = (int)(scrollX + deltaX * FOLLOW_HAND_FACTOR);
        }
        if (mIsBeingDragged && clampedY) {
            newScrollY = (int)(scrollY + deltaY * FOLLOW_HAND_FACTOR);
        }

        onOverScrolled(newScrollX, newScrollY, clampedX, clampedY);

        return clampedX || clampedY;
    }

    private boolean isVertScroll(){
        return mScroller.isVertScroll();
    }
    public AnOverScroller getScroller(){ return mScroller; }

}