react-dnd-preview

React DnD Preview

Try it here!

This project is a React component compatible with React DnD that can be used to emulate a Drag'n'Drop "ghost" when a Backend system doesn't have one (e.g. react-dnd-touch-backend).

See the migration section for instructions when switching from 4.x.x.

Installation

npm install react-dnd-preview

Usage & Example

Just include the Preview component close to the top component of your application (it places itself absolutely).

It is usable in two different ways: function-based and context-based. Both of them receive the same data formatted the same way, an object containing 3 properties:

• itemType: the type of the item (monitor.getItemType())
• item: the item (monitor.getItem())
• style: an object representing the style (used for positioning), it should be passed to the style property of your preview component

The function needs to return something that React can render (React component, null, etc).

See also the examples for more information.

Hook-based

  import { usePreview } from 'react-dnd-preview';

  const MyPreview = () => {
    const {display, itemType, item, style} = usePreview();
    if (!display) {
      return null;
    }
    return <div class="item-list__item" style={style}>{itemType}</div>;
  };

  const App = () => {
    return (
      <DndProvider backend={MyBackend}>
        <ItemList />
        <MyPreview />
      </DndProvider>
    );
  };

Function-based

  import Preview from 'react-dnd-preview';

  const generatePreview = ({itemType, item, style}) => {
    return <div class="item-list__item" style={style}>{itemType}</div>;
  };

  class App extends React.Component {
    ...

    render() {
      return (
        <DndProvider backend={MyBackend}>
          <ItemList />
          <Preview generator={generatePreview} />
          // or
          <Preview>{generatePreview}</Preview>
        </DndProvider>
      );
    }
  }

Context-based

  import Preview, { Context } from 'react-dnd-preview';

  const MyPreview = () => {
    const {itemType, item, style} = useContext(Preview.Component);
    return <div class="item-list__item" style={style}>{itemType}</div>;
  };

  const App = () => {
    return (
      <DndProvider backend={MyBackend}>
        <ItemList />
        <Preview>
          <MyPreview />
          // or
          <Context.Consumer>
            {({itemType, item, style}) => <div class="item-list__item" style={style}>{itemType}</div>}
          </Context.Consumer>
        </Preview>
      </DndProvider>
    );
  };

Migrating

Migrating from 4.x.x

Starting with 5.0.0, react-dnd-preview will start passing its arguments packed in one argument, an object {itemType, item, style}, instead of 3 different arguments (itemType, item and style). This means that will need to change your generator function to receive arguments correctly.

License

MIT, Copyright (c) 2016-2020 Louis Brunner