Class CellMeasurer

source/CellMeasurer/CellMeasurer.js:30–178

 * Cached-content is not be re-measured.
 */
export default class CellMeasurer extends React.PureComponent<Props> {
  static __internalCellMeasurerFlag = false;

  _child: {current: HTMLElement | null} = React.createRef();

  componentDidMount() {
    this._maybeMeasureCell();
  }

  componentDidUpdate() {
    this._maybeMeasureCell();
  }

  render() {
    const {children} = this.props;

    const resolvedChildren =
      typeof children === 'function'
        ? children({measure: this._measure, registerChild: this._registerChild})
        : children;

    if (resolvedChildren === null) {
      return resolvedChildren;
    }

    return cloneElement(resolvedChildren, {
      ref: node => {
        if (typeof resolvedChildren.ref === 'function') {
          resolvedChildren.ref(node);
        } else if (resolvedChildren.ref) {
          resolvedChildren.ref.current = node;
        }
        this._child.current = node;
      },
    });
  }

  _getCellMeasurements() {
    const {cache} = this.props;

    const node = this._child.current;

    // TODO Check for a bad combination of fixedWidth and missing numeric width or vice versa with height

    if (
      node &&
      node.ownerDocument &&
      node.ownerDocument.defaultView &&
      node instanceof node.ownerDocument.defaultView.HTMLElement
    ) {
      const styleWidth = node.style.width;
      const styleHeight = node.style.height;

      // If we are re-measuring a cell that has already been measured,
      // It will have a hard-coded width/height from the previous measurement.
      // The fact that we are measuring indicates this measurement is probably stale,
      // So explicitly clear it out (eg set to "auto") so we can recalculate.
      // See issue #593 for more info.