Use custom object inside react component

Question

I guess I really don't get the concept. I want to create a custom object inside a react component. The custom objects itself creates new elements.

For example: I have a custom object

function LabelEditor(canvas, width, height) {

    this.canvas = canvas;
    this.canvas.width = width;
    this.canvas.height = height;
    this.canvas.id = 'mainEditor';
    this.canvas.getContext('2d');

    console.log('hi ' + this.canvas.width  + ' / ' + this.canvas.height);

    this.getCanvas = function() {
        return this.canvas;
    };
}

Now I want to access the properties, functions and the elements created by this object inside a react component, something like this:

var Editor = React.createClass({
    render: function() {
        return (
            <div>{this.props.editor.getCanvas()}</div>
        );
    }
});

React.render(
    <Editor editor={new LabelEditor(React.DOM.canvas, 500, 500)} />,
    document.getElementsByTagName('editor')[0]
);

But every combination of props, state and something have failed by now.

The idea behind this is, I want to build an editor with fabric.js, but want to use it inside a React.js application. The fabric.js functionality will be wrapped inside a custom object with an interface to control the actions. I want to use React only as the visual part, the LabelEditor-object will as a controller, and the the fabric.js as some sort of model, providing a drawable canvas.

Brian Park · Accepted Answer · 2015-07-30 04:52:38Z

4

Below is how I would structure the code (See this JSBin for a working demo). Basically, Editor component renders <canvas> and you would instantiate your LabelEditor in componentDidMount(). You use React.findDOMNode() because <canvas> in render() represents a virtual DOM and you would need to find the corresponding DOM. Now, LabelEditor can do the drawing.

function LabelEditor(canvas, width, height) {
  this.canvas = canvas;
  this.canvas.width = width;
  this.canvas.height = height;
  this.canvas.id = 'mainEditor';

  // Draw something
  var ctx = this.canvas.getContext('2d');
  ctx.fillStyle = "#A0EBDD"
  ctx.fillRect(30, 30, 150, 150);
}

var Editor = React.createClass({
  componentDidMount: function() {
    var canvas = React.findDOMNode(this.refs.canvas);
    this._editor = new LabelEditor(canvas, this.props.width, this.props.height);
  },

  render: function() {
    return (
      <canvas ref="canvas"></canvas>
    );
  }
});

React.render(
  <Editor width={500} height={500} />,
  document.getElementById('editor')
);

answered Jul 30, 2015 at 4:52

Brian Park

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1 Comment

Ello Over a year ago

Oh! thank you. this works exactly as I want. Now I can go on and try new stuff.

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