Tim Tim - 1 month ago 8
Android Question

onClick method not working properly after NestedScrollView scrolled

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

NestedScrollView contain the LinearLayout as the root child, I put the 2 TextViews into LinearLayout to enable expand/collapse animation. The one was set Visible
and other one was set to Gone. And switching visibility by onClick event of LinearLayout

Normally, everything work as expected but when I scrolled the NestedScrollView
the onClick event not working properly. I need double click after scroll to get expand/collapse animation

Does anyone have same problem with me ? Please help me

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">

<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="98dp"
android:paddingLeft="24dp"
android:paddingRight="24dp">

<android.support.v7.widget.AppCompatTextView
android:id="@+id/detail_expense_reason_trim"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:singleLine="false"
android:textColor="@color/add_new_expense_text_color" />

<android.support.v7.widget.AppCompatTextView
android:id="@+id/detail_expense_reason"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:singleLine="false"
android:textColor="@color/add_new_expense_text_color"
android:visibility="gone" />
</LinearLayout>

</android.support.v4.widget.NestedScrollView>

<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">

<android.support.v7.widget.Toolbar
android:id="@+id/detail_expense_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
</android.support.design.widget.AppBarLayout>






@InjectView(R.id.detail_expense_reason)
AppCompatTextView originalReason;

@InjectView(R.id.detail_expense_reason_trim)
AppCompatTextView trimReason;

@InjectView(R.id.detail_expense_container)
LinearLayout expenseContainer;


// Handle event

public void onClick() {
if (originalReason.getVisibility() == View.VISIBLE) {
originalReason.setVisibility(View.GONE);
trimReason.setVisibility(View.VISIBLE);
} else {
originalReason.setVisibility(View.VISIBLE);
trimReason.setVisibility(View.GONE);
}

}

Answer

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.