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|
//CODE DU CUSTOM CONTROL
//
// A Force-Directed Diagram Layout Algorithm
// Bradley Smith - 2010/07/01
using System;
using System.Collections.Generic;
using System.Drawing;
/// <summary>
/// Represents a simple diagram consisting of nodes and connections, implementing a
/// force-directed algorithm for automatically arranging the nodes.
/// </summary>
public class Diagram {
private const double ATTRACTION_CONSTANT = 0.1; // spring constant
private const double REPULSION_CONSTANT = 10000; // charge constant
private const double DEFAULT_DAMPING = 0.5;
private const int DEFAULT_SPRING_LENGTH = 100;
private const int DEFAULT_MAX_ITERATIONS = 500;
private List<Node> mNodes;
/// <summary>
/// Gets a read-only collection of the nodes in this Diagram.
/// </summary>
public IList<Node> Nodes {
get {
return mNodes.AsReadOnly();
}
}
/// <summary>
/// Initialises a new instance of the Diagram class.
/// </summary>
public Diagram() {
mNodes = new List<Node>();
}
/// <summary>
/// Adds the specified Node to this Diagram.
/// </summary>
/// <param name="node">The Node to add to the diagram.</param>
/// <returns>True if the node was added, false if the node is already on this Diagram.</returns>
public bool AddNode(Node node) {
if (node == null) throw new ArgumentNullException("node");
if (!mNodes.Contains(node)) {
// add node, associate with diagram, then add all connected nodes
mNodes.Add(node);
node.Diagram = this;
foreach (Node child in node.Connections) AddNode(child);
return true;
}
else {
return false;
}
}
/// <summary>
/// Runs the force-directed layout algorithm on this Diagram, using the default parameters.
/// </summary>
public void Arrange() {
Arrange(DEFAULT_DAMPING, DEFAULT_SPRING_LENGTH, DEFAULT_MAX_ITERATIONS, true);
}
/// <summary>
/// Runs the force-directed layout algorithm on this Diagram, offering the option of a random or deterministic layout.
/// </summary>
/// <param name="deterministic">Whether to use a random or deterministic layout.</param>
public void Arrange(bool deterministic) {
Arrange(DEFAULT_DAMPING, DEFAULT_SPRING_LENGTH, DEFAULT_MAX_ITERATIONS, deterministic);
}
/// <summary>
/// Runs the force-directed layout algorithm on this Diagram, using the specified parameters.
/// </summary>
/// <param name="damping">Value between 0 and 1 that slows the motion of the nodes during layout.</param>
/// <param name="springLength">Value in pixels representing the length of the imaginary springs that run along the connectors.</param>
/// <param name="maxIterations">Maximum number of iterations before the algorithm terminates.</param>
/// <param name="deterministic">Whether to use a random or deterministic layout.</param>
public void Arrange(double damping, int springLength, int maxIterations, bool deterministic) {
// random starting positions can be made deterministic by seeding System.Random with a constant
Random rnd = deterministic ? new Random(0) : new Random();
// copy nodes into an array of metadata and randomise initial coordinates for each node
NodeLayoutInfo[] layout = new NodeLayoutInfo[mNodes.Count];
for (int i = 0; i < mNodes.Count; i++) {
layout[i] = new NodeLayoutInfo(mNodes[i], new Vector(), Point.Empty);
layout[i].Node.Location = new Point(rnd.Next(-50, 50), rnd.Next(-50, 50));
}
int stopCount = 0;
int iterations = 0;
while (true) {
double totalDisplacement = 0;
for (int i=0; i<layout.Length; i++) {
NodeLayoutInfo current = layout[i];
// express the node's current position as a vector, relative to the origin
Vector currentPosition = new Vector(CalcDistance(Point.Empty, current.Node.Location), GetBearingAngle(Point.Empty, current.Node.Location));
Vector netForce = new Vector(0, 0);
// determine repulsion between nodes
foreach (Node other in mNodes) {
if (other != current.Node) netForce += CalcRepulsionForce(current.Node, other);
}
// determine attraction caused by connections
foreach (Node child in current.Node.Connections) {
netForce += CalcAttractionForce(current.Node, child, springLength);
}
foreach (Node parent in mNodes) {
if (parent.Connections.Contains(current.Node)) netForce += CalcAttractionForce(current.Node, parent, springLength);
}
// apply net force to node velocity
current.Velocity = (current.Velocity + netForce) * damping;
// apply velocity to node position
current.NextPosition = (currentPosition + current.Velocity).ToPoint();
}
// move nodes to resultant positions (and calculate total displacement)
for (int i = 0; i < layout.Length; i++) {
NodeLayoutInfo current = layout[i];
totalDisplacement += CalcDistance(current.Node.Location, current.NextPosition);
current.Node.Location = current.NextPosition;
}
iterations++;
if (totalDisplacement < 10) stopCount++;
if (stopCount > 15) break;
if (iterations > maxIterations) break;
}
// center the diagram around the origin
Rectangle logicalBounds = GetDiagramBounds();
Point midPoint = new Point(logicalBounds.X + (logicalBounds.Width / 2), logicalBounds.Y + (logicalBounds.Height / 2));
foreach (Node node in mNodes) {
node.Location -= (Size)midPoint;
}
}
/// <summary>
/// Calculates the attraction force between two connected nodes, using the specified spring length.
/// </summary>
/// <param name="x">The node that the force is acting on.</param>
/// <param name="y">The node creating the force.</param>
/// <param name="springLength">The length of the spring, in pixels.</param>
/// <returns>A Vector representing the attraction force.</returns>
private Vector CalcAttractionForce(Node x, Node y, double springLength) {
int proximity = Math.Max(CalcDistance(x.Location, y.Location), 1);
// Hooke's Law: F = -kx
double force = ATTRACTION_CONSTANT * Math.Max(proximity - springLength, 0);
double angle = GetBearingAngle(x.Location, y.Location);
return new Vector(force, angle);
}
/// <summary>
/// Calculates the distance between two points.
/// </summary>
/// <param name="a">The first point.</param>
/// <param name="b">The second point.</param>
/// <returns>The pixel distance between the two points.</returns>
public static int CalcDistance(Point a, Point b) {
double xDist = (a.X - b.X);
double yDist = (a.Y - b.Y);
return (int)Math.Sqrt(Math.Pow(xDist, 2) + Math.Pow(yDist, 2));
}
/// <summary>
/// Calculates the repulsion force between any two nodes in the diagram space.
/// </summary>
/// <param name="x">The node that the force is acting on.</param>
/// <param name="y">The node creating the force.</param>
/// <returns>A Vector representing the repulsion force.</returns>
private Vector CalcRepulsionForce(Node x, Node y) {
int proximity = Math.Max(CalcDistance(x.Location, y.Location), 1);
// Coulomb's Law: F = k(Qq/r^2)
double force = -(REPULSION_CONSTANT / Math.Pow(proximity, 2));
double angle = GetBearingAngle(x.Location, y.Location);
return new Vector(force, angle);
}
/// <summary>
/// Removes all nodes and connections from the diagram.
/// </summary>
public void Clear() {
mNodes.Clear();
}
/// <summary>
/// Determines whether the diagram contains the specified node.
/// </summary>
/// <param name="node">The node to test.</param>
/// <returns>True if the diagram contains the node.</returns>
public bool ContainsNode(Node node) {
return mNodes.Contains(node);
}
/// <summary>
/// Draws the diagram using GDI+, centering and scaling within the specified bounds.
/// </summary>
/// <param name="graphics">GDI+ Graphics surface.</param>
/// <param name="bounds">Bounds in which to draw the diagram.</param>
public void Draw(Graphics graphics, Rectangle bounds) {
Point center = new Point(bounds.X + (bounds.Width / 2), bounds.Y + (bounds.Height / 2));
// determine the scaling factor
Rectangle logicalBounds = GetDiagramBounds();
double scale = 1;
if (logicalBounds.Width > logicalBounds.Height) {
if (logicalBounds.Width != 0) scale = (double)Math.Min(bounds.Width, bounds.Height) / (double)logicalBounds.Width;
}
else {
if (logicalBounds.Height != 0) scale = (double)Math.Min(bounds.Width, bounds.Height) / (double)logicalBounds.Height;
}
// draw all of the connectors first
foreach (Node node in mNodes) {
Point source = ScalePoint(node.Location, scale);
// connectors
foreach (Node other in node.Connections) {
Point destination = ScalePoint(other.Location, scale);
node.DrawConnector(graphics, center + (Size)source, center + (Size)destination, other);
}
}
// then draw all of the nodes
foreach (Node node in mNodes) {
Point destination = ScalePoint(node.Location, scale);
Size nodeSize = node.Size;
Rectangle nodeBounds = new Rectangle(center.X + destination.X - (nodeSize.Width / 2), center.Y + destination.Y - (nodeSize.Height / 2), nodeSize.Width, nodeSize.Height);
node.DrawNode(graphics, nodeBounds);
}
}
/// <summary>
/// Calculates the bearing angle from one point to another.
/// </summary>
/// <param name="start">The node that the angle is measured from.</param>
/// <param name="end">The node that creates the angle.</param>
/// <returns>The bearing angle, in degrees.</returns>
private double GetBearingAngle(Point start, Point end) {
Point half = new Point(start.X + ((end.X - start.X) / 2), start.Y + ((end.Y - start.Y) / 2));
double diffX = (double)(half.X - start.X);
double diffY = (double)(half.Y - start.Y);
if (diffX == 0) diffX = 0.001;
if (diffY == 0) diffY = 0.001;
double angle;
if (Math.Abs(diffX) > Math.Abs(diffY)) {
angle = Math.Tanh(diffY / diffX) * (180.0 / Math.PI);
if (((diffX < 0) && (diffY > 0)) || ((diffX < 0) && (diffY < 0))) angle += 180;
}
else {
angle = Math.Tanh(diffX / diffY) * (180.0 / Math.PI);
if (((diffY < 0) && (diffX > 0)) || ((diffY < 0) && (diffX < 0))) angle += 180;
angle = (180 - (angle + 90));
}
return angle;
}
/// <summary>
/// Determines the logical bounds of the diagram. This is used to center and scale the diagram when drawing.
/// </summary>
/// <returns>A System.Drawing.Rectangle that fits exactly around every node in the diagram.</returns>
private Rectangle GetDiagramBounds() {
int minX = Int32.MaxValue, minY = Int32.MaxValue;
int maxX = Int32.MinValue, maxY = Int32.MinValue;
foreach (Node node in mNodes) {
if (node.X < minX) minX = node.X;
if (node.X > maxX) maxX = node.X;
if (node.Y < minY) minY = node.Y;
if (node.Y > maxY) maxY = node.Y;
}
return Rectangle.FromLTRB(minX, minY, maxX, maxY);
}
/// <summary>
/// Removes the specified node from the diagram. Any connected nodes will remain on the diagram.
/// </summary>
/// <param name="node">The node to remove from the diagram.</param>
/// <returns>True if the node belonged to the diagram.</returns>
public bool RemoveNode(Node node) {
node.Diagram = null;
foreach (Node other in mNodes) {
if ((other != node) && other.Connections.Contains(node)) other.Disconnect(node);
}
return mNodes.Remove(node);
}
/// <summary>
/// Applies a scaling factor to the specified point, used for zooming.
/// </summary>
/// <param name="point">The coordinates to scale.</param>
/// <param name="scale">The scaling factor.</param>
/// <returns>A System.Drawing.Point representing the scaled coordinates.</returns>
private Point ScalePoint(Point point, double scale) {
return new Point((int)((double)point.X * scale), (int)((double)point.Y * scale));
}
/// <summary>
/// Private inner class used to track the node's position and velocity during simulation.
/// </summary>
private class NodeLayoutInfo {
public Node Node; // reference to the node in the simulation
public Vector Velocity; // the node's current velocity, expressed in vector form
public Point NextPosition; // the node's position after the next iteration
/// <summary>
/// Initialises a new instance of the Diagram.NodeLayoutInfo class, using the specified parameters.
/// </summary>
/// <param name="node"></param>
/// <param name="velocity"></param>
/// <param name="nextPosition"></param>
public NodeLayoutInfo(Node node, Vector velocity, Point nextPosition) {
Node = node;
Velocity = velocity;
NextPosition = nextPosition;
}
}
}
//CODE DU WINFORM QUI L'UTILISE
// A Force-Directed Diagram Layout Algorithm
// Bradley Smith - 2010/07/01
// uncomment the following line to animate the iterations of the force-directed algorithm:
//#define ANIMATE
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;
namespace ForceDirected {
public partial class Demo : Form {
Diagram mDiagram;
Random mRandom;
public Demo() {
InitializeComponent();
mDiagram = new Diagram();
mRandom = new Random();
}
protected override void OnPaint(PaintEventArgs e) {
base.OnPaint(e);
// draw with anti-aliasing and a 12 pixel border
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
mDiagram.Draw(e.Graphics, Rectangle.FromLTRB(12, 12, ClientSize.Width - 12, ClientSize.Height - 12));
}
protected override void OnResize(EventArgs e) {
base.OnResize(e);
// redraw on resize
Invalidate();
}
private void btnGenerate_Click(object sender, EventArgs e) {
mDiagram.Clear();
// create a basic, random diagram that is between 2 and 4 levels deep
// and has between 1 and 10 leaf nodes per branch
Node node = new SpotNode(Color.Black);
mDiagram.AddNode(node);
for (int i = 0; i < mRandom.Next(1, 10); i++) {
Node child = new SpotNode(Color.Navy);
node.AddChild(child);
for (int j = 0; j < mRandom.Next(0, 10); j++) {
Node grandchild = new SpotNode(Color.Blue);
child.AddChild(grandchild);
for (int k = 0; k < mRandom.Next(0, 10); k++) {
Node descendant = new SpotNode(Color.CornflowerBlue);
grandchild.AddChild(descendant);
}
}
}
// run the force-directed algorithm (async)
Cursor = Cursors.WaitCursor;
btnGenerate.Enabled = false;
Thread bg = new Thread(mDiagram.Arrange);
bg.IsBackground = true;
bg.Start();
Graphics g = CreateGraphics();
#if ANIMATE
while (bg.IsAlive) {
Invalidate();
Application.DoEvents();
Thread.Sleep(20);
}
#else
bg.Join();
#endif
btnGenerate.Enabled = true;
Cursor = Cursors.Default;
Invalidate();
}
}
} |
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