yFiles for HTML Demos Basic Features Tutorial 08 Grouping yFiles Demos

Grouped Graphs

This step shows how to configure support for grouped or hierarchically organized graphs.

Note	Collapse/expand functionality is demonstrated in the folding demo.

GraphEditorInputMode already provides default gestures for grouping/ungrouping. To use the gesture, we have to enable allowGroupingOperations.

graphEditorInputMode.allowGroupingOperations = true

Press Ctrl+G to group the currently selected nodes.

Select a child node and press Ctrl+U to ungroup. Note that this does not automatically shrink the group node or remove it if it would become empty.

Press Shift+Ctrl+G to shrink a selected group node to its minimum size.
Hold Shift when dragging nodes into or out of groups to change the graph hierarchy.

Group nodes can use special styles that are optimized to visualize a group with content. However, a group node can also use a normal node style like ShapeNodeStyle. In this example, we use GroupNodeStyle.

graph.groupNodeDefaults.style = new GroupNodeStyle({
  tabFill: '#0b7189'
})

// Set a label style with right-aligned text
graph.groupNodeDefaults.labels.style = new DefaultLabelStyle({
  horizontalTextAlignment: 'right',
  textFill: 'white'
})

// Place the label inside the tab area of the group node
// GroupNodeLabelModel is usually the most appropriate label model for GroupNodeStyle
graph.groupNodeDefaults.labels.layoutParameter =
  new GroupNodeLabelModel().createDefaultParameter()

We create some nodes and group them.

const n1 = graph.createNodeAt([30, -200])
const n2 = graph.createNodeAt([170, -200])
const n3 = graph.createNodeAt([30, -100])
graph.createEdge(n1, n3)
// Create an edge that crosses the group node boundary
graph.createEdge(n3, graph.nodes.first())

// Create a group node that encloses n1, n2 and n3
const groupNode = graph.groupNodes([n1, n2, n3])

graph.addLabel(groupNode, 'Group Node')
// Edges starting from the group node itself are also allowed
const edgeFromGroup = graph.createEdge(groupNode, graph.nodes.at(1)!)

If the group content is changed in code, i.e. a child node is added or removed programmatically, the group node size is not adjusted automatically. Instead, we have to call adjustGroupNodeLayout.

// Get a group node
const groupNode = graph.nodes.first(node => graph.isGroupNode(node))
// Create a child node that's outside the group bounds
graph.createNode({ parent: groupNode, layout: [100, -60, 30, 30] })
// Adjust the group node layout to contain the new child
graph.adjustGroupNodeLayout(groupNode)

09 Data Binding