@harnessio/pipeline-graph v1.1.0

Pipeline Graph

A library for generating and interacting with pipeline graphs.

Anatomy

• Model
• Container and Content nodes
• Edges
• Canvas

Model

Type AnyContainerNodeType us a union of LeafContainerNodeType | ParallelContainerNodeType | SerialContainerNodeType and represent one node. LeafContainerNodeType node does not have children while other have.

Example of the model

const model: AnyContainerNodeType[] = [
  {
    type: 'stage',
    children: [{ type: 'step' }, { type: 'step' }]
  }
]

In order to visualize our model we need container and content nodes.

Container and Content nodes

Container node

Container node is responsible for layout and basic user interaction like adding/deleting nodes. There are three containers: Leaf, Serial and Parallel. Leaf render one Content node, while Serial/Parallel renders itself and children.

Container node anatomy:

• Metadata - At the very root div we have data-path and data-action attributes which are used for event delegation purpose.
• Relative positioning - root div has position:relative so we can use absolute position for styling in the content node.
• Ports - Port is div. It's position is used for calculating and drawing links between ports.
• Add/Delete containers - are used for capturing mouse hover (via css). They have buttons that appears on mouse hover.

Content node

Content nodes are responsible for the content of the node (like text, icons etc.) and visualizing state (like loading or selection)

Pairing Content and Connection nodes

In order to render our graph we have to pair container and content node. For this we uses NodeContent type.

const nodes: NodeContent[] = [
  // register "step" content node which will render "StepContentNode" inside "leaf" container
  {
    type: "step",
    component: StepContentNode,
    containerType: ContainerNode.leaf
  },
  // register "stage" content node which will render "SerialGroupContentNode" inside "serial" container
  {
    type: "stage",
    component: SerialGroupContentNode
    containerType: ContainerNode.serial,
  }
]

Edges

Connection lines between nodes are drawn using svg paths. Lines are calculated using ports (which are part of container nodes).

Canvas

Library provides pan and pinch-to-zoom out of the box. For creating manual controls for zoom in/out and fit we can use useCanvasContext that exposes increment, decrement and fit functions.

Implementing custom controls example

const { increase, decrease, fit } = useCanvasContext()

return <>
    <button onClick={() => increase()}>+</button>
    <button onClick={() => decrease()}>-</button>
    <button onClick={() => fit()}>FIT</button>
</>