@cutting/use-get-parent-size - Get resize events of an observed DOM element's height, width etc. from a resize-observer.

install

pnpm add @cutting/use-get-parent-size

# or

npm install @cutting/use-get-parent-size

useParentSize

A React hook that allows you to use a ResizeObserver to measure an element's size.

usage

const { width, height } = useParentSize(ref, options);

useParentSize takes a react ref object and an optional options object.

Returns the contentRect of the observed element:

interface DOMRectReadOnly {
  readonly bottom: number;
  readonly height: number;
  readonly left: number;
  readonly right: number;
  readonly top: number;
  readonly width: number;
  readonly x: number;
  readonly y: number;
  toJSON(): any;
}

Options

export interface UseParentSizeOptions {
  debounceDelay: number;
  initialValues: Partial<ResizeObserverContentRect>;
  transformFunc?: (
    entry: Partial<ResizeObserverContentRect>
  ) => Partial<ResizeObserverContentRect>;
  maxDifference?: number;
  transformFunc?: ({ width, height }: Dimensions) => Dimensions;
  callback?(entry: ResizeObserverContentRect): void;
}

• debounceDelay - default 500ms. an optional number that will throttle the speed at which reize events are raised to the calling code.
• initialValues - initially, the ref will be null and no width or height values can be returned until it is mounted. The initialValues option can return a specific width and height value until the ref actually references a valid DOM node. e.g. const { width, height } = useParentSize(ref, { width: 100, height: 50});

Default is an empty DomRect:

{
 bottom: undefined,
 height: undefined,
 left: undefined,
 width: undefined,
 right: undefined,
 top: undefined,
 x: undefined,
 y: undefined,
};

• transformFunc optional function to transform the results, e.g. to halve the size of the parent

  transformFunc: ({ width, height }) => ({
    width: width / 2,
    height: height / 2,
  });

  Default is identity, (x) => x

• maxDifference (default 10) - useParentSize stores the current DomRect values in memory and if a resize event occurrs, these values are checked against the new DomRect values after the resize. If the difference between the two values is greater than the maxDifference option then clients are notified.

• callback a function can be provided that is executed on each resize.

Usage

Used to properly resize an svg

import { useRef } from 'react';
import type { UseParentSizeOptions } from '@cutting/use-get-parent-size';

export function ResponsiveSVG({
  children
}): JSX.Element => {
  const ref = useRef<HTMLDivElement>(null);
  const { width, height } = useParentSize(ref, options);
  const aspect = width / height;

  const adjustedHeight = Math.ceil(width / aspect);

  return (
    <div ref={ref}>
      <svg
        viewBox={`${origin.x} ${origin.y} ${width} ${adjustedHeight}`}
      >
        {children}
      </svg>
    </div>
  );
};

Used with callback only

const Pipeline = () => {
  const controller = useVisualizationController();
  const containerRef = useRef<HTMLDivElement>(null);

  useParentSize(containerRef, {
    callback: () => {
      controller.getGraph().fit(70);
    },
    debounceDelay: 500,
  });