Configuring the port size

Unlike nodes, ports do not possess an intrinsic size. A port is defined merely by a point. The port style can define how large the port should be rendered. In the previous step, we used fix values that resulted in a circle with a diameter of 6. In this sample, we will add a property to the port style that allows us to customize the size of the circle.

First, we add a constructor that defines a size property with a default value of 6.

constructor(size: number = 6) {
  super()
  this.size = size
}

Now we can use this value in createVisual to configure the size of the circle.

const radius = this.size * 0.5
ellipseElement.setAttribute('rx', String(radius))
ellipseElement.setAttribute('ry', String(radius))

We also adjust getBounds to consider the size property.

protected getBounds(context: ICanvasContext, port: IPort): Rect {
  const { x, y } = port.location
  const radius = this.size * 0.5
  return new Rect(x - radius, y - radius, this.size, this.size)
}

Note	A port does not have to be visualized as a circle, of course. Any shape is possible. In this tutorial, we use a circle for simplicity.

Now, we can create multiple style instances that use different sizes.

const defaultPortStyle = new CustomPortStyle()
const largePortStyle = new CustomPortStyle(10)
const smallPortStyle = new CustomPortStyle(4)

graph.addPort({
  owner: owner,
  locationParameter: FreeNodePortLocationModel.CENTER,
  style: smallPortStyle
})

03 Render Performance