source: stable/HeuristicLab.ExtLibs/HeuristicLab.Netron/3.0.2672.12446/Netron.Diagramming.Core-3.0.2672.12446/Layout/BalloonTreeLayout.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using Netron.Diagramming.Core.Analysis;
namespace Netron.Diagramming.Core {
  /// <summary>
  /// <para>Layout that computes a circular "balloon-tree" layout of a tree.
  /// This layout places children nodes radially around their parents, and is
  ///equivalent to a top-down flattened view of a ConeTree.</para>
  /// 
  /// <para>The algorithm used is that of G. Melançon and I. Herman from their
  /// research paper Circular Drawings of Rooted Trees, Reports of the Centre for 
  /// Mathematics and Computer Sciences, Report Number INS–9817, 1998.</para>
  /// </summary>
  class BalloonTreeLayout : TreeLayoutBase {
    #region Fields

    private int m_minRadius = 2;
    private Dictionary<string, Params> Pars;
    BackgroundWorker worker;

    #endregion

    #region Properties


    /// <summary>
    /// Gets or sets the MinRadius
    /// </summary>
    public int MinRadius {
      get { return m_minRadius; }
      set { m_minRadius = value; }
    }

    #endregion

    #region Constructor
    ///<summary>
    ///Default constructor
    ///</summary>
    public BalloonTreeLayout(IController controller)
      : base("Balloon TreeLayout", controller) {
    }
    #endregion

    #region Methods
    /// <summary>
    /// Layouts this instance.
    /// </summary>
    public void Layout() {
      FirstWalk(LayoutRoot as INode);
      SecondWalk(LayoutRoot as INode, null, LayoutRoot.Rectangle.X, LayoutRoot.Rectangle.Y, 1, 0);
    }
    /// <summary>
    /// Inits this instance.
    /// </summary>
    /// <returns></returns>
    private bool Init() {


      this.Graph = this.Model as IGraph;

      if (Graph == null)
        throw new InconsistencyException("The model has not been set and the Graph property is hence 'null'");

      this.LayoutRoot = this.Controller.Model.LayoutRoot;//could be null if not set in the GUI
      Graph.ClearSpanningTree();
      Graph.MakeSpanningTree(LayoutRoot as INode);

      Pars = new Dictionary<string, Params>();
      if (Graph.Nodes.Count == 0)
        return false;
      if (Graph.Edges.Count == 0) //this layout is base on embedded springs in the connections
        return false;


      Params par;

      foreach (INode node in Graph.Nodes) {
        par = new Params();
        Pars.Add(node.Uid.ToString(), par);
      }
      return true;
    }

    /// <summary>
    /// First traversal.
    /// </summary>
    /// <param name="n">The n.</param>
    private void FirstWalk(INode n) {
      Params np = Pars[n.Uid.ToString()];
      np.d = 0;
      double s = 0;
      if (n.Children != null) {
        foreach (INode c in n.Children) {
          //if (!c.isVisible()) continue;
          FirstWalk(c);
          Params cp = Pars[c.Uid.ToString()];
          np.d = Math.Max(np.d, cp.r);
          cp.a = Math.Atan(((double)cp.r) / (np.d + cp.r));
          s += cp.a;
        }
      }
      AdjustChildren(np, s);
      SetRadius(np);
    }
    /// <summary>
    /// Second traversal.
    /// </summary>
    /// <param name="n">The n.</param>
    /// <param name="r">The r.</param>
    /// <param name="x">The x.</param>
    /// <param name="y">The y.</param>
    /// <param name="l">The l.</param>
    /// <param name="t">The t.</param>
    private void SecondWalk(INode n, INode r, double x, double y, double l, double t) {
      setX(n, r, x);
      setY(n, r, y);

      Params np = Pars[n.Uid.ToString()];

      double dd = l * np.d;
      double p = t + Math.PI;
      double fs = (n.ChildCount == 0 ? 0 : np.f / n.ChildCount);
      double pr = 0;
      if (n.Children != null) {
        foreach (INode c in n.Children) {

          //if (!c.isVisible()) continue;
          Params cp = Pars[c.Uid.ToString()];
          double aa = np.c * cp.a;
          double rr = np.d * Math.Tan(aa) / (1 - Math.Tan(aa));
          p += pr + aa + fs;
          double xx = (l * rr + dd) * Math.Cos(p);
          double yy = (l * rr + dd) * Math.Sin(p);
          pr = aa;
          SecondWalk(c, n, x + xx, y + yy, l * np.c/*l*rr/cp.r*/, p);
        }
      }
    }
    /// <summary>
    /// Sets the radius.
    /// </summary>
    /// <param name="np">The np.</param>
    private void SetRadius(Params np) {
      np.r = Convert.ToInt32((Math.Max(np.d, m_minRadius) + 2 * np.d) / 2.1D);
    }
    /// <summary>
    /// Adjusts the children.
    /// </summary>
    /// <param name="np">The np.</param>
    /// <param name="s">The s.</param>
    private void AdjustChildren(Params np, double s) {
      if (s > Math.PI) {
        np.c = Math.PI / s;
        np.f = 0;
      } else {
        np.c = 1;
        np.f = Math.PI - s;
      }
    }
    /// <summary>
    /// Runs this instance.
    /// </summary>
    public override void Run() {
      Run(2000);
    }
    /// <summary>
    /// Runs the specified time.
    /// </summary>
    /// <param name="time">The time.</param>
    public override void Run(int time) {
      worker = new BackgroundWorker();
      worker.DoWork += new DoWorkEventHandler(worker_DoWork);
      worker.RunWorkerAsync(time);
    }
    /// <summary>
    /// Stops this instance.
    /// </summary>
    public override void Stop() {
      if (worker != null && worker.IsBusy)
        worker.CancelAsync();
    }
    /// <summary>
    /// Handles the DoWork event of the worker control.
    /// </summary>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">The <see cref="T:System.ComponentModel.DoWorkEventArgs"/> instance containing the event data.</param>
    private void worker_DoWork(object sender, DoWorkEventArgs e) {
      Init();
      Layout();
    }


    #endregion

    #region Classes

    /// <summary>
    /// Paramter blob to temporarily keep working data of one node.
    /// </summary>
    class Params {
      public int d;
      public int r;
      //public double rx;
      //public double ry;
      public double a;
      public double c;
      public double f;
    }

    #endregion
  }
}