index.js

import React, { Component } from 'react';
import PropTypes from 'prop-types';
import {
  requireNativeComponent,
  View,
  UIManager,
  findNodeHandle,
  DeviceEventEmitter,
  ColorPropType
} from 'react-native';

class SketchView extends Component {
  constructor(props) {
    super(props);
    this.onChange = this.onChange.bind(this);
    this.subscriptions = [];
  }

  onChange(event) {
    console.log('save event: ',event.nativeEvent);
    if (event.nativeEvent.type === "onSaveSketch") {

      if (!this.props.onSaveSketch) {
        return;
      }

      this.props.onSaveSketch({
        localFilePath: event.nativeEvent.event.localFilePath,
        imageWidth: event.nativeEvent.event.imageWidth,
        imageHeight: event.nativeEvent.event.imageHeight
      });
    }
  }

  componentDidMount() {
    if (this.props.onSaveSketch) {
      let sub = DeviceEventEmitter.addListener(
        'onSaveSketch',
        this.props.onSaveSketch
      );
      this.subscriptions.push(sub);
    }
  }

  componentWillUnmount() {
    this.subscriptions.forEach(sub => sub.remove());
    this.subscriptions = [];
  }

  render() {
    return (
      <RNSketchView {... this.props} onChange={this.onChange}/>
    );
  }

  clearSketch() {
    UIManager.dispatchViewManagerCommand(
      findNodeHandle(this),
      UIManager.getViewManagerConfig('RNSketchView').Commands.clearSketch,
      [],
    );
  }

  saveSketch() {
    UIManager.dispatchViewManagerCommand(
      findNodeHandle(this),
      UIManager.getViewManagerConfig('RNSketchView').Commands.saveSketch,
      [],
    );
  }

  changeTool(toolId) {
    UIManager.dispatchViewManagerCommand(
      findNodeHandle(this),
      UIManager.getViewManagerConfig('RNSketchView').changeTool,
      [toolId],
    );
  }

}

SketchView.constants = {
  toolType: {
    pen: {
      id: 0,
      name: 'Pen',
    },
    eraser: {
      id: 1,
      name: 'Eraser'
    }
  }
};

SketchView.propTypes = {
  ...View.propTypes,
  selectedTool: PropTypes.number,
  toolColor: ColorPropType,
  localSourceImagePath: PropTypes.string
};

let RNSketchView = requireNativeComponent('RNSketchView', SketchView, {
  nativeOnly: { onChange: true }
});

export default SketchView;