👀 Views: 0 💬 Answers: 1 📅 Created: 2025-07-22

html react canvas javascript

I've looked through the documentation and I'm still confused about I'm working on a React 18 application where I use an HTML `<canvas>` element to render some graphics based on user input. The scenario I'm working with is that when I update the state that controls the drawing parameters, the canvas does not seem to re-render as expected. I've tried using the `useEffect` hook to trigger a redraw whenever the state changes, but it still doesn't update. Here's a simplified version of my code: ```javascript import React, { useRef, useEffect, useState } from 'react'; const CanvasComponent = () => { const canvasRef = useRef(null); const [color, setColor] = useState('black'); const draw = (ctx) => { ctx.fillStyle = color; ctx.fillRect(0, 0, 100, 100); }; useEffect(() => { const canvas = canvasRef.current; const ctx = canvas.getContext('2d'); ctx.clearRect(0, 0, canvas.width, canvas.height); draw(ctx); }, [color]); return ( <div> <canvas ref={canvasRef} width={200} height={200} /> <button onClick={() => setColor(color === 'black' ? 'red' : 'black')}>Change Color</button> </div> ); }; export default CanvasComponent; ``` When I click the button to change the color, the canvas does not update as expected, and the rectangle remains the same color. The `draw` function is not being called again when the state changes. I'm not getting any behavior messages, but the canvas is exploring on the initial render color. Any help on what I might be missing here would be appreciated! This is part of a larger service I'm building. Any help would be greatly appreciated! My development environment is Ubuntu. Thanks in advance!