package bluej.utility.javafx.binding;

import javafx.beans.binding.DoubleBinding;
import javafx.geometry.Bounds;
import javafx.scene.control.ScrollPane;




| An observable binding to the height of a ScrollPane's viewport height.
|
public class ViewportHeightBinding
extends DoubleBinding{    
   private ScrollPane scroll;

   
   public ViewportHeightBinding(ScrollPane scroll)
   {        
      this.scroll = scroll;
      bind(scroll.viewportBoundsProperty());     
      }

   
   @Override
   
   protected double computeValue()
   {
      Bounds viewBound = scroll.getViewportBounds();
      return viewBound == null ? 0.0 : viewBound.getHeight();     
      } 
   }