onClick method not working properly after NestedScrollView scrolled

Question

I used NestedScrollView with CoordinatorLayout to enable scroll animation for Toolbar (by app:layout_scrollFlags=\"scroll|enterAlways\").

NestedScrollView contain th

Answer 1

It is a Bug mention at Google #issues 194398.

Just need to use this WorkaroundNestedScrollView.java class which extends NestedScrollView like,

WorkaroundNestedScrollView.java

public class WorkaroundNestedScrollView extends NestedScrollView {

public WorkaroundNestedScrollView(Context context, AttributeSet attrs) {
    super(context, attrs);
}

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
    if (ev.getAction() == MotionEvent.ACTION_DOWN) {
        // Explicitly call computeScroll() to make the Scroller compute itself
        computeScroll();
    }
    return super.onInterceptTouchEvent(ev);
}
}

And in yourlayout use it like this,

layout.xml

<com.yourpackagename.whatever.WorkaroundNestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent">
...
...

</com.yourpackagename.whatever.WorkaroundNestedScrollView>

You can alson find more details here.

Answer 2

Best solution :

1) Create this class :

public class FixAppBarLayoutBehavior extends AppBarLayout.Behavior {

public FixAppBarLayoutBehavior() {
    super();
}

public FixAppBarLayoutBehavior(Context context, AttributeSet attrs) {
    super(context, attrs);
}

@Override
public void onNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target,
        int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type) {
    super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed,
            dxUnconsumed, dyUnconsumed, type);
    stopNestedScrollIfNeeded(dyUnconsumed, child, target, type);
}

@Override
public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child,
        View target, int dx, int dy, int[] consumed, int type) {
    super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type);
    stopNestedScrollIfNeeded(dy, child, target, type);
}

private void stopNestedScrollIfNeeded(int dy, AppBarLayout child, View target, int type) {
    if (type == ViewCompat.TYPE_NON_TOUCH) {
        final int currOffset = getTopAndBottomOffset();
        if ((dy < 0 && currOffset == 0)
                || (dy > 0 && currOffset == -child.getTotalScrollRange())) {
            ViewCompat.stopNestedScroll(target, ViewCompat.TYPE_NON_TOUCH);
        }
    }
}}

2) And use in xml :

<android.support.design.widget.AppBarLayout
...
app:layout_behavior="yourPackageName.FixAppBarLayoutBehavior"
...>

Answer 3

I met this problem too

    public class NestedScrollView extends FrameLayout implements NestedScrollingParent,
    NestedScrollingChild, ScrollingView {
       @Override
        public boolean onTouchEvent(MotionEvent ev) {
          switch (actionMasked) {
            case MotionEvent.ACTION_DOWN: {
                if (getChildCount() == 0) {
                    return false;
                }
                //add this line
                if (!inChild((int) ev.getX(), (int) ev.getY())) {
                    return false;
                }
                if ((mIsBeingDragged = !mScroller.isFinished())) {
                        final ViewParent parent = getParent();
                    if (parent != null) {
                        parent.requestDisallowInterceptTouchEvent(true);
                    }
                }
           }
      }

and I change my xml file,change paddingTop to margin_top,then my top floating view's OnClick event will not be intercepted by NestedScrollView

Answer 4

I've opened another issue here: https://issuetracker.google.com/issues/68103042 as it still seems to be an issue in Oreo for us (multiple devices, including emulators).

My fix (adapted from ta..@graymeter.com's suggestions at https://issuetracker.google.com/issues/37051723) doesn't require modifying AOSP code as it uses reflection:

public class MyNestedScrollView extends NestedScrollView {

    private static final Logger sLogger = LogFactory.getLogger(MyNestedScrollView.class);

    private OverScroller mScroller;
    public boolean isFling = false;

    public MyNestedScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mScroller = getOverScroller();
    }

    @Override
    public void fling(int velocityY) {
        super.fling(velocityY);

        // here we effectively extend the super class functionality for backwards compatibility and just call invalidateOnAnimation()
        if (getChildCount() > 0) {
            ViewCompat.postInvalidateOnAnimation(this);

            // Initializing isFling to true to track fling action in onScrollChanged() method
            isFling = true;
        }
    }

    @Override
    protected void onScrollChanged(int l, final int t, final int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);

        if (isFling) {
            if (Math.abs(t - oldt) <= 3 || t == 0 || t == (getChildAt(0).getMeasuredHeight() - getMeasuredHeight())) {
                isFling = false;

                // This forces the mFinish variable in scroller to true (as explained the
                //    mentioned link above) and does the trick
                if (mScroller != null) {
                    mScroller.abortAnimation();
                }
            }
        }
    }

    private OverScroller getOverScroller() {
        Field fs = null;
        try {
            fs = this.getClass().getSuperclass().getDeclaredField("mScroller");
            fs.setAccessible(true);
            return (OverScroller) fs.get(this);
        } catch (Throwable t) {
            return null;
        }
    }
}

Answer 5

It is a bug of the NestedScrollView, the detail of the bug can be found in here: issue. The problem is that mScroller.isFinished() in onInterceptTouchEvent(MotionEvent ev) will not return true after a fling operation (even if the fling is stopped). Therefore the touch event is intercepted.

This bug have been reported for a while, but still have not been fixed. So I have created by own version of bug fix for this problem. I implemented my own NestedScrollView, copied all the code from NestedScrollView and having the with the following amendments:

public class NestedScrollView extends FrameLayout implements NestedScrollingParent, NestedScrollingChild {
    ...
    private void initScrollView() {
        ...
        // replace this line:
        // mScroller = new ScrollerCompat(getContext(), null);
        mScroller = ScrollerCompat.create(getContext(), null);
        ...
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        ...
        switch (action & MotionEventCompat.ACTION_MASK) {
            ...
            case MotionEvent.ACTION_DOWN: {
                ...
                // replace this line:
                // mIsBeingDragged = !mScroller.isFinished();
                mIsBeingDragged = false;
                ...
            }
        }
    }   
}

And this NestedScrollView should have the same behaviour as the original one.

Answer 6

This was an issue in support libraries. see this https://issuetracker.google.com/u/1/issues/37070828

If you are using androidX then

'androidx.appcompat:appcompat:1.1.0-alpha04'.

will probably fix this issue though this is an alpha build.