This sample creates state charts, and more specifically, finite-state machines. A finite-state machine is a mathematical model of computation used to design computer programs and sequential logic circuits.

The text is editable for both the nodes and the links. The user can draw as many links from one node to another node as desired, and the links can be reshaped or deleted when selected. Double-clicking in the background of the diagram creates a new node. The mouse wheel is set to zoom in and out instead of scroll.

This sample customizes the Part.selectionAdornmentTemplate of the node to a template that contains a button The button is positioned to be at the Top-Right corner of the node by being in a Spot Panel with its GraphObject.alignment property set to Spot.TopRight.

The Button's GraphObject.click method creates a new node data, adds it to the model, and creates a link from the original node data to the new node data. All of this is done inside a transaction, so that it can be undone by the user (Ctrl+Z and Ctrl+Y will undo and redo transactions). After the node is created, Diagram.scrollToRect is called in case it is off-screen.

Diagram Model saved in JSON format:
{ "class": "go.GraphLinksModel", "nodeKeyProperty": "id", "nodeDataArray": [ { "id": 0, "loc": "120 120", "text": "Initial" }, { "id": 1, "loc": "330 120", "text": "First down" }, { "id": 2, "loc": "226 376", "text": "First up" }, { "id": 3, "loc": "60 276", "text": "Second down" }, { "id": 4, "loc": "226 226", "text": "Wait" } ], "linkDataArray": [ { "from": 0, "to": 0, "text": "up or timer", "curviness": -20 }, { "from": 0, "to": 1, "text": "down", "curviness": 20 }, { "from": 1, "to": 0, "text": "up (moved)\nPOST", "curviness": 20 }, { "from": 1, "to": 1, "text": "down", "curviness": -20 }, { "from": 1, "to": 2, "text": "up (no move)" }, { "from": 1, "to": 4, "text": "timer" }, { "from": 2, "to": 0, "text": "timer\nPOST" }, { "from": 2, "to": 3, "text": "down" }, { "from": 3, "to": 0, "text": "up\nPOST\n(dblclick\nif no move)" }, { "from": 3, "to": 3, "text": "down or timer", "curviness": 20 }, { "from": 4, "to": 0, "text": "up\nPOST" }, { "from": 4, "to": 4, "text": "down" } ] }