利用canvas、js 创作出 字符动画

<video id="video" oncanplay="init()" loop src="./2.mp4" width="400"></video>
    <canvas id="cvs"></canvas>
    <canvas id="cvs2" onclick="video.play()" ></canvas>

css部分代码

 body {
            display: flex;
        }

        video,
        canvas {
            border: 2px solid black;
        }

js代码

 const init = () => {
            const ctx = cvs.getContext('2d')
            const ctx2 = cvs2.getContext('2d')
            //把视频的宽高赋值给cvs 和cvs2
            cvs.height = cvs2.height = video.offsetHeight
            cvs.width = cvs2.width = video.offsetWidth

            // 定义一个函数
            const playVideo = () => {
                requestAnimationFrame(playVideo)
                const { width, height } = cvs
                // 把video复刻到cvs1中
                ctx.drawImage(video, 0, 0, width, height)
                const data = ctx.getImageData(0, 0, width, height).data
                //每次渲染之前 先要把cav2清空一下
                ctx2.clearRect(0, 0, width, height)

                // 定义一个稀释比例
                const bl = 8
                ctx2.font = '12px serif'
                /**
                 * +=4 是因为RGBA是有四个  所以要设置成为4个
                */
                for (let i = 0; i < data.length; i += 4 * bl) {
                    const x = parseInt((i + 1) % (width * 4) / 4)
                    const y = parseInt(i / (width * 4))
                    if (x % bl === 0 && y % bl === 0) {
                        // 转灰度图  从网上抄的
                        const g = parseInt((data[i] + data[i + 1] + data[i + 2]) / 3.3)
                        ctx2.fillStyle = `rgba(${g},${g},${g},${data[i + 3]})`
                        ctx2.fillText('8',x,y)
                    }
                }
            }
            playVideo()
        }