Now we can create a simple Petri net:<\/p>\n
Net CreateSampleNet()\n{\n\tvar net = new Net();\n\n\tvar p1 = new Place { Label = \"P1\", Tokens = 1 };\n\tvar p2 = new Place { Label = \"P2\", Tokens = 0 };\n\tvar p3 = new Place { Label = \"P3\", Tokens = 2 };\n\tvar p4 = new Place { Label = \"P4\", Tokens = 1 };\n\n\tnet.Places.AddRange(new[] { p1, p2, p3, p4 });\n\n\tvar t1 = new Transition { Label = \"T1\" };\n\tvar t2 = new Transition { Label = \"T2\" };\n\n\tnet.Transitions.AddRange(new[] { t1, t2 });\n\n\tvar a1 = new Arc(p1, t1);\n\tvar a2 = new Arc(t1, p2);\n\tvar a3 = new Arc(t1, p3);\n\tvar a4 = new Arc(p2, t2);\n\tvar a5 = new Arc(p3, t2);\n\tvar a6 = new Arc(t2, p4);\n\tvar a7 = new Arc(t2, p1);\n\n\tnet.Arcs.AddRange(new[] { a1, a2, a3, a4, a5, a6, a7 });\n\n\treturn net;\n}<\/pre>\nNext, drop a DiagramView and Diagram objects on the form which we’ll use to visualize the net. Add the following method to create diagram elements representing the model objects, and run LayeredLayout to arrange them:<\/p>\n
void BuildDiagram(Net net)\n{\n\tvar nodeMap = new Dictionary<node, diagramnode=\"\">();\n\n\tvar placeBounds = new RectangleF(0, 0, 16, 16);\n\tvar transBounds = new RectangleF(0, 0, 6, 20);\n\n\tforeach (var place in net.Places)\n\t{\n\t\tvar node = diagram.Factory.CreateShapeNode(placeBounds);\n\t\tnode.Text = place.Label;\n\t\tnode.TextFormat.LineAlignment = StringAlignment.Far;\n\t\tnode.Shape = Shapes.Ellipse;\n\t\tnode.Tag = place.Tokens;\n\t\tnode.CustomDraw = CustomDraw.Additional;\n\t\tnodeMap[place] = node;\n\t}\n\n\tforeach (var trans in net.Transitions)\n\t{\n\t\tvar node = diagram.Factory.CreateShapeNode(transBounds);\n\t\tnode.Text = trans.Label;\n\t\tnode.TextFormat.LineAlignment = StringAlignment.Far;\n\t\tnode.Shape = Shapes.Rectangle;\n\t\tnodeMap[trans] = node;\n\t}\n\n\tforeach (var arc in net.Arcs)\n\t{\n\t\tvar link = diagram.Factory.CreateDiagramLink(\n\t\t\tnodeMap[arc.Input], nodeMap[arc.Output]);\n\t\tlink.Tag = arc.Multiplicity;\n\t\tlink.HeadShape = ArrowHeads.PointerArrow;\n\t}\n\n\tvar layout = new LayeredLayout();\n\tlayout.Orientation = Orientation.Horizontal;\n\tlayout.StraightenLongLinks = true;\n\tlayout.Arrange(diagram);\n}<\/node,><\/pre>\nWe will use the DrawNode custom draw event to render marks associated with each place. Another possibility is to create a custom node class and override its Draw method.<\/p>\n
void OnDrawNode(object sender, DrawNodeEventArgs e)\n{\n\tvar node = e.Node;\n\tvar g = e.Graphics;\n\n\tif (node.Tag is int)\n\t{\n\t\tvar tokens = (int)node.Tag;\n\t\tvar cx = node.Bounds.Width \/ 2;\n\t\tvar cy = node.Bounds.Height \/ 2;\n\n\t\tif (tokens == 1)\n\t\t{\n\t\t\tfloat r = cx \/ 2;\n\t\t\tDrawMark(cx, cy, r, g);\n\t\t}\n\t\telse if (tokens == 2)\n\t\t{\n\t\t\tfloat r = 2 * cx \/ 5;\n\t\t\tDrawMark(cx \/ 2, cy, r, g);\n\t\t\tDrawMark(3 * cx \/ 2, cy, r, g);\n\t\t}\n\t\telse if (tokens == 3)\n\t\t{\n\t\t\tfloat r = cx \/ 3;\n\t\t\tfloat y2 = 4 * cy \/ 3;\n\t\t\tDrawMark(cx, 2 * cy \/ 5, r, g);\n\t\t\tDrawMark(cx \/ 2, y2, r, g);\n\t\t\tDrawMark(3 * cx \/ 2, y2, r, g);\n\t\t}\n\t}\n}\n\nvoid DrawMark(float x, float y, float r, IGraphics g)\n{\n\tg.FillEllipse(Brushes.Black, x - r, y - r, r * 2, r * 2);\n}<\/pre>\nFinally, set some appearance properties and call the methods above to build the diagram:<\/p>\n
public MainForm()\n{\n\tInitializeComponent();\n\n\tdiagram.ShadowsStyle = ShadowsStyle.None;\n\tdiagram.DiagramLinkStyle.Brush = new MindFusion.Drawing.SolidBrush(Color.Black);\n\tdiagram.ShapeNodeStyle.Brush = new MindFusion.Drawing.SolidBrush(Color.White);\n\tdiagram.ShapeNodeStyle.FontSize = 10f;\n\tdiagram.ShapeNodeStyle.FontStyle = FontStyle.Bold;\n\n\tvar textAbove = new[]\n\t{\n\t\tnew LineTemplate(-100, -100, 200, -100),\n\t\tnew LineTemplate(200, -100, 200, 0),\n\t\tnew LineTemplate(200, 0, -100, 0),\n\t\tnew LineTemplate(-100, 0, -100, -100)\n\t};\n\tShapes.Ellipse.TextArea = textAbove;\n\tShapes.Rectangle.TextArea = textAbove;\n\n\tvar net = CreateSampleNet();\n\tBuildDiagram(net);\n}<\/pre>\nThe final result is displayed below.
\n![\"Petri](\"http:\/\/mindfusion.dev\/_samples\/petri_net.png\")
<\/p>\n
The complete sample project is available for download here:
\nPetriNet.zip<\/a><\/p>\nFor more information on Petri nets, see this Wikipedia article:
\nhttp:\/\/en.wikipedia.org\/wiki\/Petri_net<\/a><\/p>\nAll MindFusion.Diagramming libraries expose the same programming interface, so most of the sample code shown above will work with only a few modifications in WPF, ASP.NET, Silverlight and Java versions of the control.<\/p>\n
Enjoy!<\/p>\n","protected":false},"excerpt":{"rendered":"
In this post we show how to build a Petri net using MindFusion.Diagramming for WinForms. Petri nets are used to model and study distributed systems. A net contains places, transitions and arcs. A place represents possible state of the system, … Continue reading