CODEWITHSUNDEEP
androidandroid-xmlandroid-coordinatorlayoutcoordinator-layout
Karen Forde
Karen Forde

Reputation: 1127

Programmatically scrolling to specific view in CoordinatorLayout, or sticky behaviour

I've got a CoordinatorLayout, and I need to programmatically scroll vertically to have a specific view anchored to the top as a sticky view. The stickiness works by having an AppBarLayout with app:layout_scrollFlags="scroll|snap" set on the view I want to make sticky. The programmatically scrolling of the CoordinatorLayout is proving to be problematic.

The structure of the CoordinatorLayout content is:

<com.google.android.material.appbar.AppBarLayout
 …   
</com.google.android.material.appbar.AppBarLayout>

<!--list of reviews-->
<RecyclerView
    ../>


<androidx.constraintlayout.widget.ConstraintLayout
    ..
</androidx.constraintlayout.widget.ConstraintLayout>

<com.google.android.material.floatingactionbutton.FloatingActionButton
   .. />

I've tried scrollTo, scrollBy but can't seem to calculate the correct value for Y. I thought height - view.top would do it but it didn't.

I've tried wrapping in a ScrollView but this caused a RecyclerView in the same layout to disappear, and the smoothScroll didn't work anyway.

I've tried 

val view = mLayout.findViewById<ConstraintLayout>(R.id.view)
val rect = Rect(0, 0, view.getWidth(), view.getHeight())
view.requestRectangleOnScreen(rect, true) // and tried false

I've tried view.parent.requestChildFocus(view, view)

--

I'm now trying a new approach, I'm trying to set the views above the one I need to scroll to to View.GONE - which works, except that setting the views above as GONE causes the anchored view to lose its 'stickiness'. I tried adding this view above it but still once I set the above views to GONE the stickiness won't work.

<View
        android:id="@+id/sticky_helper"
        android:layout_width="wrap_content"
        android:layout_height="1dp"
        app:layout_scrollFlags="scroll|snap"/>

However when I just set the views to INVISIBLE the stickiness still works so it seems to be to do with setting them to GONE even though the above view is still visible.

If anyone has a workaround for the stickiness, or indeed knows how to scroll to specific view in CoordinatorLayout I'd be very grateful.

Upvotes: 0

Views: 1627

Answers (1)

Marat Zangiev
Marat Zangiev

Reputation: 1402

Hope, this will help you:

  1. scroll your RecyclerView to 0 position:

    recyclerView.smoothScrollToPosition(0)

  2. Expand your AppBarLayout:

    app_bar.setExpanded(true, true)

And bacause of I don't know what is inside your AppBarLayout can't say how to scroll it in right way :) But your AppBarLayout will be expanded and all of it's views will be shown

Upvotes: 2

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