react-annotator

react-annotator

A React mixin to allow for user annotations directly on images, similar to Red Pen. An example can be seen here.

Getting Started

• npm install --save react-annotator
• var ReactAnnotatorMixin = require('react-annotator').Mixin
• mixins: [ReactAnnotatorMixin({settings})]
• call this.renderAnnotationIndicators() in the component's render() function, in order to render the individual indicators at the top-level of the component element.

var ReactAnnotatorMixin = require('react-annotator').Mixin;
var annotatorSettings = {
  element: '.annotator-parent-image',
  annotations: [
    {
      text: 'This is an annotation on the image.',
      xPos: 127,
      yPos: 431
    },
    {
      text: 'This is another annotation on the image.',
      xPos: 513,
      yPos: 289
    }
  ]
};

var App = React.createClass({

  mixins: [ReactAnnotatorMixin(annotatorSettings)],

  ...

  render: function() {
    return (
      <div>
        ...
        {this.renderAnnotationIndicators()}
      </div>
    );
  }

});

Note: Any interactive elements within the parent component must call event.stopPropagation() on click to prevent triggering the new annotation form.

Options

A Javascript object is passed to the ReactAnnotatorMixin to specify options, as well as any previously created or saved annotations (there is also a method to define these asychronously, discussed below.) The options are:

• element (string): the element selector for the parent element which the annotations are intended for. No default value, and the annotation system will not be rendered without a valid element.
• annotations (array): the array of annotations to be displayed on the parent element. Defaults to an empty array.
• addCallback (function): a function to be called any time a new annotation is entered. The callback is invoked with a single parameter, an object representing the annotation saved (of the format below). Defaults to an empty function.

Each "annotation" in the array represents one indicator on the parent element, which triggers its textual annotation when triggered. An annotation has the following structure:

{
  "text": "The tip, comment, note, etc. that was saved for this annotation.",
  "xPos": "The X coordinate of the annotation indicator, in relation to the parent element.",
  "yPos": "The Y coordinate of the annotation indicator, in relation to the parent element."
}

Methods

Upon including the mixin, a handful of functions will be available to your component. Some of these are intended strictly for internal use in the mixin (all prefixed with an underscore), but there are a few that are intended to provide you with more complex options and interactions. These are outlined below.

setAnnotations(annotations, cb)

This function is intended to provide you with a method to asynchronously define your annotations (if they need to be fetched from a database, etc.) It takes a list of annotations (of the form discussed earlier), along with an optional callback function as parameters. This will completely overwrite any existing annotations, setting this.state.annotations equal to the annotations parameter. Once the state is updated, the callback function will be invoked.

setAddCallback(cb)

This function allows you to asynchronously define the callback that will be invoked any time a new annotation is entered (mentioned above under Options). Useful when you need to access props or state in the callback.

addAnnotation(annotation, cb)

This function takes an annotation (of the form discussed earlier), along with an optional callback function as parameters. It pushes the new annotation onto the existing list, updates its state, and invokes the callback function.

removeAnnotation(annotation, cb)

This function takes an annotation (of the form discussed earlier), along with an optional callback function as parameters. It iterates over the current list of annotations, removing any determined to be equal to the annotation passed (using lodash's _.isEqual function.) The state is then updated accordingly, and the callback function is invoked.

getAnnotations()

This returns the list of annotations currently within the mixin's state. This is essentially a wrapper for the value this.state.annotations.

Styling

Some basic styling is provided in /dist/css/annotator.css. This can either be included directly in your project, or used as a base for your own custom styles. Below, the HTML structure of the annotation system is also outlined for custom styling.

The annotation system consists of two main elements for each annotation: an indicator and a tooltip. An indicator is a small, simple element positioned absolutely on the parent element. Upon hover, the associated annotation is triggered which the user can then read.

In addition, when an empty space is clicked on the parent element an annotation form is triggered. This allows the user to enter the annotation text to be saved for that point.

Indicator

<div class="annotator-indicator"></div>

Annotation

<div class="annotator-tooltip">
  <p>{Text of annotation.}</p>
</div>

Form

<form class="annotator-form">
  <textarea></textarea>
</form>

Testing

All tests for this package are within the __tests__/ directory. If you wish to run the tests:

• git clone [e-mail]:jakemmarsh/react-annotator.git
• cd react-annotator
• npm install
• npm test