BottomNavigationBehavior.java

package com.blargh.android.utils;

import java.util.logging.Logger;

import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.Snackbar;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;

public class BottomNavigationBehavior<V extends View>  extends CoordinatorLayout.Behavior<V> {

	final private static Logger log = Logger.getLogger(BottomNavigationBehavior.class.getName());
	
	public BottomNavigationBehavior (Context context, AttributeSet attrs) {
		super(context, attrs);
	}
	
	public BottomNavigationBehavior () {
		super();
	}
	
	@Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, V child, View directTargetChild,
    		View target, int axes, int type) {
        return axes == ViewCompat.SCROLL_AXIS_VERTICAL;
    }
	
	@Override
	public void onNestedPreScroll (CoordinatorLayout coordinatorLayout, 
            V child, 
            View target, 
            int dx, 
            int dy, 
            int[] consumed, 
            int type) {
		   
		super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type);
	   child.setTranslationY(Math.max(0f, Math.min(child.getHeight(), child.getTranslationY() + dy)));
	}
	
	
	@Override 
	public boolean layoutDependsOn(CoordinatorLayout parent, V child, View dependency) {
		if(dependency instanceof Snackbar.SnackbarLayout) {
			updateSnackbar(child, (Snackbar.SnackbarLayout)dependency);
		}
		
		return super.layoutDependsOn(parent, child, dependency);
	}
	
	
	private void updateSnackbar(View child, Snackbar.SnackbarLayout snackbarLayout) {
		if(snackbarLayout.getLayoutParams() instanceof CoordinatorLayout.LayoutParams) {
			CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams)snackbarLayout.getLayoutParams();
			
			params.setAnchorId(child.getId());
		    params.anchorGravity = Gravity.TOP;
		    params.gravity = Gravity.TOP;
		    snackbarLayout.setLayoutParams(params);
		}
	}
		

}