Building collaborative drawing applications with suspense in React

16 Oct 2023

In this blog post, we’ll explore how to create a collaborative drawing application using React and suspense. Drawing applications are fun and can be made even more interesting by allowing multiple users to collaborate in real-time. We’ll use suspense to handle the asynchronous loading of resources and ensure a smooth user experience.

Introduction
Setting up the project
Creating the drawing canvas
Implementing collaborative drawing
Handling suspense and loading state
Conclusion

Introduction

Collaborative drawing applications allow multiple users to draw simultaneously on a shared canvas. This can be a great way to engage users in a fun and collaborative activity, whether it’s for remote teams, online classrooms, or just for friends to doodle together.

React provides a powerful tool called suspense, which enables us to handle asynchronous loading in a declarative way. We can leverage suspense to load resources such as drawing data, user interactions, and collaborative updates.

Setting up the project

Before we begin, make sure you have Node.js and npm installed on your machine. Start by creating a new React project with the following command:

npx create-react-app collaborative-drawing-app

Navigate into the newly created directory:

cd collaborative-drawing-app

Install additional dependencies:

npm install react-firebase-hooks firebase

These dependencies will help us with real-time collaboration using Firebase.

Creating the drawing canvas

Next, let’s create the drawing canvas component. We’ll use HTML5 canvas element to render the drawing area and handle user interactions.

import React, { useRef, useEffect } from 'react';

const DrawingCanvas = () => {
  const canvasRef = useRef(null);
  const contextRef = useRef(null);

  useEffect(() => {
    const canvas = canvasRef.current;
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;

    const context = canvas.getContext('2d');
    context.lineCap = 'round';
    context.strokeStyle = 'black';
    context.lineWidth = 2;

    contextRef.current = context;
  }, []);

  return <canvas ref={canvasRef} />;
};

export default DrawingCanvas;

In this component, we create a canvas element and set its width and height to match the window size. We also set up the context with some default drawing options.

Implementing collaborative drawing

To enable collaborative drawing, we’ll use Firebase as our real-time database. We can leverage the useCollection hook from react-firebase-hooks to synchronize drawing data between users.

First, let’s set up the Firebase configuration and initialize the Firestore instance in our App.js file:

import firebase from 'firebase/app';
import 'firebase/firestore';

const firebaseConfig = {
  // Add your Firebase configuration here
};

firebase.initializeApp(firebaseConfig);
const firestore = firebase.firestore();

Now we can use the useCollection hook in our DrawingCanvas component to listen for updates on the drawing data:

import { useCollection } from 'react-firebase-hooks/firestore';

const DrawingCanvas = () => {
  // other code...

  const [snapshot] = useCollection(firestore.collection('drawings'));

  if (!snapshot) {
    return <div>Loading...</div>;
  }

  const drawings = snapshot.docs.map((doc) => doc.data());

  // rendering and user interaction code...
}

Here, we retrieve the drawings collection from Firestore and listen for updates using the useCollection hook. We map the snapshot’s documents to an array of drawing data.

Handling suspense and loading state

With the use of suspense, we can handle the loading state when retrieving the drawing data. Let’s modify the DrawingCanvas component to use suspense to wrap the rendering logic:

import React, { useRef, useEffect } from 'react';

const DrawingCanvas = () => {
  // other code...

  if (!snapshot) {
    throw new Promise((resolve) => setTimeout(resolve, 2000));
  }

  const drawings = snapshot.docs.map((doc) => doc.data());

  // rendering and user interaction code...
}

By throwing a promise inside the if (!snapshot) condition, we simulate a loading state for 2 seconds. Suspense will capture the promise and display a fallback UI, such as a loading spinner, until the data is loaded.

Conclusion

In this blog post, we explored how to build a collaborative drawing application using React and suspense. We learned how to set up the project, create a drawing canvas, implement collaborative drawing using Firebase, and handle suspense for loading state.

Collaborative drawing applications can be a fun and engaging way to connect with others. Using React and suspense, we can create smooth and interactive experiences for users across different devices. So go ahead and start building your own collaborative drawing application and let your creativity flow!

#hashtags: #React #CollaborativeDrawing

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