yFiles for HTML Demos Tutorial: Node Style Implementation 02 Create A Custom Shape yFiles Demos

A more interesting shape

Currently, the custom node style renders a rectangle. This is something yFiles for HTML already offers out-of-the box with ShapeNodeStyle and RectangleNodeStyle. So let’s use something a little more interesting, for example a typical card shape with a tab in the top left corner.

protected createVisual(context: IRenderContext, node: INode): Visual | null {
  const { x, y, width, height } = node.layout

  const pathElement = document.createElementNS(
    'http://www.w3.org/2000/svg',
    'path'
  )
  pathElement.setAttribute('d', createPathData(x, y, width, height))
  pathElement.setAttribute('fill', '#0b7189')
  pathElement.setAttribute('stroke', '#042d37')

  // wrap the SVG path into an SvgVisual
  return new SvgVisual(pathElement)
}

Note	The createVisual method can return anything SVG supports. You are not limited to `<rect>` or `<path>` here. This tutorial focuses on how yFiles for HTML works, so we try to keep it simple. For more information about the capabilities of SVG, take a look at the SVG specification.

The path data is created by a separate function that takes the node’s location and size into account:

const tabWidth = 50
const tabHeight = 10

/**
 * Creates the path data for the SVG path element.
 */
function createPathData(
  x: number,
  y: number,
  width: number,
  height: number
): string {
  return (
    `M ${x} ${y} ` +
    `h ${tabWidth} ` +
    `v ${tabHeight} ` +
    `h ${width - tabWidth} ` +
    `v ${height - tabHeight} ` +
    `h ${-width} z`
  )
}

03 Render Performance