/*
    * Copyright (c) 2005, The JUNG Authors 
    *
    * All rights reserved.
    *
    * This software is open-source under the BSD license; see either
    * "license.txt" or
    * https://github.com/jrtom/jung/blob/master/LICENSE for a description.
    * Created on Mar 8, 2005
   *
   */
  package edu.uci.ics.jung.visualization.control;
  
  import java.awt.geom.Point2D;
  
  import edu.uci.ics.jung.visualization.Layer;
  import edu.uci.ics.jung.visualization.VisualizationServer;
  import edu.uci.ics.jung.visualization.transform.MutableTransformer;
  
  /** 
   * LayoutScalingControl applies a scaling transformation to the graph layout.
   * The Vertices get closer or farther apart, but do not themselves change
   * size. ScalingGraphMouse uses MouseWheelEvents to apply the scaling.
   * 
   * @author Tom Nelson
   */
  public class LayoutScalingControl implements ScalingControl {
  
      /**
  	 * zoom the display in or out, depending on the direction of the
  	 * mouse wheel motion.
  	 */
      public void scale(VisualizationServer<?, ?> vv, float amount, Point2D from) {
          
          Point2D ivtfrom = vv.getRenderContext().getMultiLayerTransformer()
          	.inverseTransform(Layer.VIEW, from);
          MutableTransformer modelTransformer = vv.getRenderContext().getMultiLayerTransformer()
          	.getTransformer(Layer.LAYOUT);
          modelTransformer.scale(amount, amount, ivtfrom);
          vv.repaint();
      }
  }