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source: trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.Views/3.4/LayoutEngines/ReingoldTilfordLayoutEngine.cs @ 10531

Last change on this file since 10531 was 10531, checked in by bburlacu, 10 years ago

#2076: SymbolicExpressionTreeChart: initialize layout when the tree node is changed, not when the tree draw method is called.

File size: 11.3 KB
Line 
1
2using System;
3using System.Collections.Generic;
4using System.Drawing;
5using System.Linq;
6
7namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.Views {
8  public class ReingoldTilfordLayoutEngine<T> : ILayoutEngine<T> where T : class {
9    private readonly Dictionary<T, LayoutNode<T>> nodeMap; // provides a reverse mapping T => LayoutNode
10    public int NodeWidth { get; set; }
11    public int NodeHeight { get; set; }
12    private int minHorizontalSpacing = 5;
13    public int HorizontalSpacing {
14      get { return minHorizontalSpacing; }
15      set { minHorizontalSpacing = value; }
16    }
17
18    private int minVerticalSpacing = 5;
19    public int VerticalSpacing {
20      get { return minVerticalSpacing; }
21      set { minVerticalSpacing = value; }
22    }
23
24    public Func<T, IEnumerable<T>> GetChildren { get; set; }
25    public Func<T, int> GetLength { get; set; }
26    public Func<T, int> GetDepth { get; set; }
27    private LayoutNode<T> layoutRoot;
28
29    public ReingoldTilfordLayoutEngine() {
30      nodeMap = new Dictionary<T, LayoutNode<T>>();
31    }
32
33    public ReingoldTilfordLayoutEngine(T root, Func<T, IEnumerable<T>> childrenFunc)
34      : this() {
35      Initialize(root, childrenFunc);
36    }
37
38    public void Initialize(T root, Func<T, IEnumerable<T>> getChildren, Func<T, int> getLength = null, Func<T, int> getDepth = null) {
39      GetChildren = getChildren;
40      Clear();
41      var node = new LayoutNode<T> { Content = root, Width = NodeWidth, Height = NodeHeight };
42      node.Ancestor = node;
43      layoutRoot = node;
44      Expand(node);
45    }
46
47    private void Expand(LayoutNode<T> lRoot) {
48      nodeMap.Add(lRoot.Content, lRoot);
49      var children = GetChildren(lRoot.Content).ToList();
50      if (!children.Any()) return;
51      lRoot.Children = new List<LayoutNode<T>>(children.Count);
52      for (int i = 0; i < children.Count; ++i) {
53        var node = new LayoutNode<T> {
54          Content = children[i],
55          Number = i,
56          Parent = lRoot,
57          Level = lRoot.Level + 1,
58          Width = NodeWidth,
59          Height = NodeHeight
60        };
61        node.Ancestor = node;
62        lRoot.Children.Add(node);
63        Expand(node);
64      }
65    }
66
67    public IEnumerable<VisualTreeNode<T>> GetVisualNodes() {
68      return nodeMap.Values.Select(x => new VisualTreeNode<T>(x.Content) {
69        Width = (int)Math.Round(x.Width),
70        Height = (int)Math.Round(x.Height),
71        X = (int)Math.Round(x.X),
72        Y = (int)Math.Round(x.Y)
73      });
74    }
75
76    public IEnumerable<LayoutNode<T>> GetLayoutNodes() {
77      return nodeMap.Values;
78    }
79
80    public void AddNode(T content) {
81      if (nodeMap.ContainsKey(content)) { throw new ArgumentException("Content already present in the dictionary."); }
82      var node = new LayoutNode<T> { Content = content };
83      nodeMap.Add(content, node);
84    }
85
86    public void AddNode(LayoutNode<T> node) {
87      var content = node.Content;
88      if (nodeMap.ContainsKey(content)) { throw new ArgumentException("Content already present in the dictionary."); }
89      nodeMap.Add(content, node);
90    }
91
92    public void AddNodes(IEnumerable<LayoutNode<T>> nodes) {
93      foreach (var node in nodes)
94        nodeMap.Add(node.Content, node);
95    }
96
97    public LayoutNode<T> GetNode(T content) {
98      LayoutNode<T> layoutNode;
99      nodeMap.TryGetValue(content, out layoutNode);
100      return layoutNode;
101    }
102
103    public void ResetCoordinates() {
104      foreach (var node in nodeMap.Values) {
105        node.ResetCoordinates();
106      }
107    }
108
109    public Dictionary<T, PointF> GetCoordinates() {
110      return nodeMap.ToDictionary(x => x.Key, x => new PointF(x.Value.X, x.Value.Y));
111    }
112
113    /// <summary>
114    /// Transform LayoutNode coordinates so that all coordinates are positive and start from (0,0)
115    /// </summary>
116    private void NormalizeCoordinates() {
117      var nodes = nodeMap.Values.ToList();
118      float xmin = 0, ymin = 0;
119      foreach (var node in nodes) {
120        if (xmin > node.X) xmin = node.X;
121        if (ymin > node.Y) ymin = node.Y;
122      }
123      foreach (var node in nodes) {
124        node.X -= xmin;
125        node.Y -= ymin;
126      }
127    }
128
129    public void Center(float width, float height) {
130      // center layout on screen
131      var bounds = Bounds();
132      float dx = 0, dy = 0;
133      if (width > bounds.Width) { dx = (width - bounds.Width) / 2f; }
134      if (height > bounds.Height) { dy = (height - bounds.Height) / 2f; }
135      foreach (var node in nodeMap.Values) { node.Translate(dx, dy); }
136    }
137
138    public void FitToBounds(float width, float height) {
139      var bounds = Bounds();
140      var myWidth = bounds.Width;
141      var myHeight = bounds.Height;
142
143      if (myWidth <= width && myHeight <= height) return; // no need to fit since we are within bounds
144
145      var layers = nodeMap.Values.GroupBy(node => node.Level, node => node).ToList();
146
147      if (myWidth > width) {
148        // need to scale horizontally
149        float x = width / myWidth;
150        foreach (var node in layers.SelectMany(g => g)) {
151          node.X *= x;
152          node.Width *= x;
153        }
154        float spacing = minHorizontalSpacing * x;
155        foreach (var layer in layers) {
156          var nodes = layer.ToList();
157          float minWidth = float.MaxValue;
158          for (int i = 0; i < nodes.Count - 1; ++i) { minWidth = Math.Min(minWidth, nodes[i + 1].X - nodes[i].X); }
159          float w = Math.Min(NodeWidth, minWidth - spacing);
160          foreach (var node in nodes) {
161            node.X += (node.Width - w) / 2f;
162            node.Width = w;
163            //this is a simple solution to ensure that the leftmost and rightmost nodes are not drawn partially offscreen due to scaling and offset
164            //this should work well enough 99.9% of the time with no noticeable visual difference
165            if (node.X < 0) {
166              node.Width += node.X;
167              node.X = 0;
168            } else if (node.X + node.Width > width) {
169              node.Width = width - node.X;
170            }
171          }
172        }
173      }
174      if (myHeight > height) {
175        // need to scale vertically
176        float x = height / myHeight;
177        foreach (var node in layers.SelectMany(g => g)) {
178          node.Y *= x;
179          node.Height *= x;
180        }
181      }
182    }
183
184    public void Clear() {
185      layoutRoot = null;
186      nodeMap.Clear();
187    }
188
189    public void Reset() {
190      foreach (var layoutNode in nodeMap.Values) {
191        // reset layout-related parameters
192        layoutNode.Reset();
193      }
194    }
195
196    public void CalculateLayout() {
197      if (layoutRoot == null) throw new Exception("Layout layoutRoot cannot be null.");
198      Reset(); // reset node parameters like Mod, Shift etc. and set coordinates to 0
199      FirstWalk(layoutRoot);
200      SecondWalk(layoutRoot, -layoutRoot.Prelim);
201      NormalizeCoordinates();
202    }
203
204    public void CalculateLayout(float width, float height) {
205      CalculateLayout();
206      FitToBounds(width, height);
207      Center(width, height);
208    }
209
210    /// <summary>
211    /// Returns the bounding box for this layout. When the layout is normalized, the rectangle should be [0,0,xmin,xmax].
212    /// </summary>
213    /// <returns></returns>
214    public RectangleF Bounds() {
215      float xmin = 0, xmax = 0, ymin = 0, ymax = 0;
216      var list = nodeMap.Values.ToList();
217      foreach (LayoutNode<T> node in list) {
218        float x = node.X, y = node.Y;
219        if (xmin > x) xmin = x;
220        if (xmax < x) xmax = x;
221        if (ymin > y) ymin = y;
222        if (ymax < y) ymax = y;
223      }
224      return new RectangleF(xmin, ymin, xmax + minHorizontalSpacing + NodeWidth, ymax + minVerticalSpacing + NodeHeight);
225    }
226
227    #region methods specific to the reingold-tilford layout algorithm
228    private void FirstWalk(LayoutNode<T> v) {
229      LayoutNode<T> w;
230      if (v.IsLeaf) {
231        w = v.LeftSibling;
232        if (w != null) {
233          v.Prelim = w.Prelim + minHorizontalSpacing + NodeWidth;
234        }
235      } else {
236        var defaultAncestor = v.Children[0]; // leftmost child
237
238        foreach (var child in v.Children) {
239          FirstWalk(child);
240          Apportion(child, ref defaultAncestor);
241        }
242        ExecuteShifts(v);
243        var leftmost = v.Children.First();
244        var rightmost = v.Children.Last();
245        float midPoint = (leftmost.Prelim + rightmost.Prelim) / 2;
246        w = v.LeftSibling;
247        if (w != null) {
248          v.Prelim = w.Prelim + minHorizontalSpacing + NodeWidth;
249          v.Mod = v.Prelim - midPoint;
250        } else {
251          v.Prelim = midPoint;
252        }
253      }
254    }
255
256    private void SecondWalk(LayoutNode<T> v, float m) {
257      v.X = v.Prelim + m;
258      v.Y = v.Level * (minVerticalSpacing + NodeHeight);
259      if (v.IsLeaf) return;
260      foreach (var child in v.Children) {
261        SecondWalk(child, m + v.Mod);
262      }
263    }
264
265    private void Apportion(LayoutNode<T> v, ref LayoutNode<T> defaultAncestor) {
266      var w = v.LeftSibling;
267      if (w == null) return;
268      LayoutNode<T> vip = v;
269      LayoutNode<T> vop = v;
270      LayoutNode<T> vim = w;
271      LayoutNode<T> vom = vip.LeftmostSibling;
272
273      float sip = vip.Mod;
274      float sop = vop.Mod;
275      float sim = vim.Mod;
276      float som = vom.Mod;
277
278      while (vim.NextRight != null && vip.NextLeft != null) {
279        vim = vim.NextRight;
280        vip = vip.NextLeft;
281        vom = vom.NextLeft;
282        vop = vop.NextRight;
283        vop.Ancestor = v;
284        float shift = (vim.Prelim + sim) - (vip.Prelim + sip) + minHorizontalSpacing + NodeWidth;
285        if (shift > 0) {
286          var ancestor = Ancestor(vim, v) ?? defaultAncestor;
287          MoveSubtree(ancestor, v, shift);
288          sip += shift;
289          sop += shift;
290        }
291        sim += vim.Mod;
292        sip += vip.Mod;
293        som += vom.Mod;
294        sop += vop.Mod;
295      }
296      if (vim.NextRight != null && vop.NextRight == null) {
297        vop.Thread = vim.NextRight;
298        vop.Mod += (sim - sop);
299      }
300      if (vip.NextLeft != null && vom.NextLeft == null) {
301        vom.Thread = vip.NextLeft;
302        vom.Mod += (sip - som);
303        defaultAncestor = v;
304      }
305    }
306
307    private void MoveSubtree(LayoutNode<T> wm, LayoutNode<T> wp, float shift) {
308      int subtrees = wp.Number - wm.Number; // TODO: Investigate possible bug (if the value ever happens to be zero) - happens when the tree is actually a graph (but that's outside the use case of this algorithm which only works with trees)
309      if (subtrees == 0) throw new Exception("MoveSubtree failed: check if object is really a tree (no cycles)");
310      wp.Change -= shift / subtrees;
311      wp.Shift += shift;
312      wm.Change += shift / subtrees;
313      wp.Prelim += shift;
314      wp.Mod += shift;
315    }
316
317    private void ExecuteShifts(LayoutNode<T> v) {
318      if (v.IsLeaf) return;
319      float shift = 0;
320      float change = 0;
321      for (int i = v.Children.Count - 1; i >= 0; --i) {
322        var w = v.Children[i];
323        w.Prelim += shift;
324        w.Mod += shift;
325        change += w.Change;
326        shift += (w.Shift + change);
327      }
328    }
329
330    private LayoutNode<T> Ancestor(LayoutNode<T> u, LayoutNode<T> v) {
331      var ancestor = u.Ancestor;
332      if (ancestor == null) return null;
333      return ancestor.Parent == v.Parent ? ancestor : null;
334    }
335    #endregion
336  }
337}
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