Function DragLayer

packages/react-dnd/src/DragLayer.js:10–126

(collect, options = {})

import checkDecoratorArguments from './utils/checkDecoratorArguments';

export default function DragLayer(collect, options = {}) {
  checkDecoratorArguments('DragLayer', 'collect[, options]', ...arguments); // eslint-disable-line prefer-rest-params
  invariant(
    typeof collect === 'function',
    'Expected "collect" provided as the first argument to DragLayer ' +
    'to be a function that collects props to inject into the component. ',
    'Instead, received %s. ' +
    'Read more: http://react-dnd.github.io/react-dnd/docs-drag-layer.html',
    collect,
  );
  invariant(
    isPlainObject(options),
    'Expected "options" provided as the second argument to DragLayer to be ' +
    'a plain object when specified. ' +
    'Instead, received %s. ' +
    'Read more: http://react-dnd.github.io/react-dnd/docs-drag-layer.html',
    options,
  );

  return function decorateLayer(DecoratedComponent) {
    const { arePropsEqual = shallowEqualScalar } = options;
    const displayName =
      DecoratedComponent.displayName ||
      DecoratedComponent.name ||
      'Component';

    class DragLayerContainer extends Component {
      static DecoratedComponent = DecoratedComponent;

      static displayName = `DragLayer(${displayName})`;

      static contextTypes = {
        dragDropManager: PropTypes.object.isRequired,
      }

      getDecoratedComponentInstance() {
        invariant(
          this.child,
          'In order to access an instance of the decorated component it can ' +
          'not be a stateless component.',
        );
        return this.child;
      }

      shouldComponentUpdate(nextProps, nextState) {
        return !arePropsEqual(nextProps, this.props) ||
          !shallowEqual(nextState, this.state);
      }

      constructor(props, context) {
        super(props);
        this.handleChange = this.handleChange.bind(this);

        this.manager = context.dragDropManager;
        invariant(
          typeof this.manager === 'object',
          'Could not find the drag and drop manager in the context of %s. ' +
          'Make sure to wrap the top-level component of your app with DragDropContext. ' +