Similar to LayoutWithoutAView, but demonstrates the use of the incremental layout capabilities provided by IncrementalHierarchicLayouter. This too can be achieved without the classes that are only present in the yFiles Viewer distribution.

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 ** This file is part of yFiles-2.6. 
 ** 
 ** yWorks proprietary/confidential. Use is subject to license terms.
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 ** Redistribution of this file or of an unauthorized byte-code version
 ** of this file is strictly forbidden.
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package demo.layout;

import java.util.HashMap;
import y.base.DataMap;
import y.geom.YPoint;
import y.layout.*;
import y.layout.DefaultLayoutGraph;
import y.layout.BufferedLayouter;
import y.util.D;
import y.base.Edge;
import y.base.EdgeMap;
import y.base.Node;
import y.layout.PortConstraint;
import y.layout.PortConstraintKeys;
import y.layout.hierarchic.IncrementalHierarchicLayouter;
import y.layout.hierarchic.incremental.IncrementalHintsFactory;
import y.util.Maps;

/**
 * This demo shows how to use the incremental hierarchical layout algorithm
 * without using classes that are only present in the yFiles Viewer Distribution. 
 * In this demo, first a graph will be layouted from scratch. Then new graph elements
 * will be added to the graph structure. Finally, an updated layout for the
 * grown graph structure will be calculated. The updated layout
 * will still look similar to the original layout. This feature
 * is called incremental layout.
 * <br>
 * This demo displays the calculated coordinates before and
 * after the incremental layout step in a simple graph viewer.
 * Additionally it outputs the calculated coordinates of the graph layout to
 * the console.
 */
public class IncrementalLayoutWithoutAView
{
  
  /**
   * Launcher
   */
  public static void main(String[] args)
  {
    IncrementalLayoutWithoutAView lwv = new IncrementalLayoutWithoutAView();
    lwv.doit();
  }
  
  /**
   * Uses IncrementalHierarchicLayouter to perform an incremental layout of a graph.
   */
  public void doit()
  {
    DefaultLayoutGraph graph = new DefaultLayoutGraph();
    
    //construct graph. assign sizes to nodes
    Node v1 = graph.createNode();
    graph.setSize(v1,30,30);
    Node v2 = graph.createNode();
    graph.setSize(v2,30,30);
    Node v3 = graph.createNode();
    graph.setSize(v3,30,30);
    
    Edge e1 = graph.createEdge(v1,v2);
    Edge e2 = graph.createEdge(v1,v3);
 
    //optionally setup some port constraints for HierarchicLayouter
    EdgeMap spc = graph.createEdgeMap();
    EdgeMap tpc = graph.createEdgeMap();
    //e1 shall leave and enter the node on the right side
    spc.set(e1, PortConstraint.create(PortConstraint.EAST));
    //additionally set a strong port constraint on the target side. 
    tpc.set(e1, PortConstraint.create(PortConstraint.EAST, true));
    //ports with strong port constraints will not be reset by the 
    //layouter.  So we specify the target port right now to connect 
    //to the upper left corner of the node 
    graph.setTargetPointRel(e1, new YPoint(15, -15));
    
    //e2 shall leave and enter the node on the top side
    spc.set(e2, PortConstraint.create(PortConstraint.NORTH));
    tpc.set(e2, PortConstraint.create(PortConstraint.NORTH));
    
    graph.addDataProvider(PortConstraintKeys.SOURCE_PORT_CONSTRAINT_KEY, spc);
    graph.addDataProvider(PortConstraintKeys.TARGET_PORT_CONSTRAINT_KEY, tpc);
    
    IncrementalHierarchicLayouter layouter = new IncrementalHierarchicLayouter();
    layouter.setLayoutMode(IncrementalHierarchicLayouter.LAYOUT_MODE_FROM_SCRATCH);
    
    new BufferedLayouter(layouter).doLayout(graph);
    
    //display result
    LayoutPreviewPanel lpp1 = new LayoutPreviewPanel(new CopiedLayoutGraph(graph));
    lpp1.createFrame("Hierarchical").setVisible(true);
    
    D.bug("\n\nGRAPH LAID OUT HIERARCHICALLY FROM SCRATCH");
    D.bug("v1 center position = " + graph.getCenter(v1));
    D.bug("v2 center position = " + graph.getCenter(v2));
    D.bug("v3 center position = " + graph.getCenter(v3));
    D.bug("e1 path = " + graph.getPath(e1));
    D.bug("e2 path = " + graph.getPath(e2));

    //now add a node and two edges incrementally...
    Node v4 = graph.createNode();
    graph.setSize(v4,30,30);
    
    Edge e3 = graph.createEdge(v1,v4);
    Edge e4 = graph.createEdge(v4,v2);
    
    IncrementalHintsFactory ihf = layouter.createIncrementalHintsFactory();
    DataMap map = Maps.createDataMap(new HashMap());
    
    map.set(v4, ihf.createLayerIncrementallyHint(v4));
    map.set(e3, ihf.createSequenceIncrementallyHint(e3));
    map.set(e4, ihf.createSequenceIncrementallyHint(e4));
    
    graph.addDataProvider(IncrementalHierarchicLayouter.INCREMENTAL_HINTS_DPKEY, map);
    layouter.setLayoutMode(IncrementalHierarchicLayouter.LAYOUT_MODE_INCREMENTAL);
    
    new BufferedLayouter(layouter).doLayout(graph);
    
    //display result
    LayoutPreviewPanel lpp2 = new LayoutPreviewPanel(graph);
    lpp2.createFrame("Hierarchical with incrementally added elements").setVisible(true);

    D.bug("\n\nGRAPH AFTER ELEMENTS HAVE BEEN ADDED INCREMENTALLY");
    D.bug("v1 center position = " + graph.getCenter(v1));
    D.bug("v2 center position = " + graph.getCenter(v2));
    D.bug("v3 center position = " + graph.getCenter(v3));
    D.bug("v4 center position = " + graph.getCenter(v4));
    D.bug("e1 path = " + graph.getPath(e1));
    D.bug("e2 path = " + graph.getPath(e2));
    D.bug("e3 path = " + graph.getPath(e3));
    D.bug("e4 path = " + graph.getPath(e4));
  }
}