Android BottomSheet: How can I know if user is dragging up or down the bottomsheet?

Question

I have an app with bottomsheet opened upto 90% of the screen height. How can I know if the user is dragging up/down the bottomsheet. I read we can use onSlide() but the offset values are NaN and sometimes outright weird, so it seems kinda unreliable. Any help is appreciated. Thanks in advance.

Answer 1

bottomsheet documention doens't work but i think i figured it out to clear up the documentation read:

Hidden state is -1.0, collapsed state is 0.0 and expanded state is 1.0.

for me i see it only going from 1 to 0, and 0 to 1. That is because i did not have a hidden state, my sheeet was always to be shown at a peekheight. So as an example, if you have a sheet that will never been hidden you can try this:

just keep a property variable called oldOffSet and then do this:

behavior.addBottomSheetCallback(object : BottomSheetBehavior.BottomSheetCallback() {
    var oldOffSet = 0f
    override fun onSlide(bottomSheet: View, slideOffset: Float) {
    
        val inRangeExpanding = oldOffSet < slideOffset
        val inRangeCollapsing = oldOffSet > slideOffset
        oldOffSet = slideOffset
    }
}

Answer 2

You can add a BottomSheetCallback to know the status and the direction.

Something like:

    BottomSheetBehavior<...> bottomSheetBehavior = BottomSheetBehavior.from(bottomSheetLayout);

    bottomSheetBehavior.addBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {

      @Override public void onStateChanged(@NonNull View bottomSheet, int newState) {
        if (newState == BottomSheetBehavior.STATE_DRAGGING){
            // Dragging state
        }    
      }

      @Override public void onSlide(@NonNull View bottomSheet, float slideOffset) {
        // The new offset of this bottom sheet within [-1,1] range. 
        // Offset increasesas this bottom sheet is moving upward. 
        // From 0 to 1 the sheet is between collapsed and expanded states and 
        // From -1 to 0 it is between hidden and collapsed states.
      }
    });