js 选择一个音频文件，绘制音频的波形，从右向左逐渐前进。

选择一个音频文件，绘制波形，从右向左逐渐前进。

完整代码：

<template><div><input type="file" @change="handleFileChange" accept="audio/*" /><button @click="stopPlayback" :disabled="!isLoaded">停止</button><canvas ref="canvas" width="1201" height="211"></canvas></div>
</template><script>
import axios from "axios";export default {data() {return {// audioUrl:"http://121.41.225.74:9091/mintti/app/storage/newFile/b26uvk9ipd8n5iop1lzs.wav",audioUrl: "http://121.41.225.74:9091/mintti/app/storage/newFile/c19xqqqtd8ywqyaf8gno.wav",// audioUrl: "http://121.41.225.74:9091/mintti/app/storage/newFile/d3msxipdfxrbyijm3ys0.wav",// audioUrl:"http://121.41.225.74:9091/mintti/app/storage/newFile/xm456t9dptsrigxye84q.wav",dataArray: [],isPlaying: false,isLoaded: false,drawInterval: 200, // 设置绘制的时间间隔（单位：毫秒）drawIntervalId: null,fileData: new Int8Array(0),index: 0,mWidth: 0,mHeight: 0,}},mounted() {const ctx = this.$refs.canvas.getContext('2d')this.drawGrid(ctx)this.downloadAudio()},methods: {// 下载音频文件downloadAudio() {axios({method: 'get',url: this.audioUrl,responseType: 'arraybuffer'}).then(res => {if (!res) {return;}console.log("decodeAudioData")this.loadAudio(res.data)}).catch(error => {console.error('下载音频时出错:', error);});;},handleFileChange(event) {this.isLoaded = falseconst file = event.target.files[0]this.stopPlayback()const reader = new FileReader();reader.onload = (e) => {console.log("onLoad")this.loadAudio(e.target.result)};reader.readAsArrayBuffer(file);},loadAudio(res) {this.dataArray = []this.isLoaded = truethis.index = 0;// 获取文件的前 100 个字节this.fileData = new Int8Array(res);this.refreshData()this.drawIntervalId = setInterval(() => {console.log("定时器执行了")this.refreshData()}, this.drawInterval)//循环读取},refreshData() {let i = this.indexconsole.log("文件总长度：" + this.fileData.byteLength + ",,i=" + i)if (i * 1600 + 44 > this.fileData.byteLength) {clearInterval(this.drawIntervalId)return}const byteArray = this.fileData.slice(i * 1600 + 44, (i + 1) * 1600 + 44);// 创建一个新的 Uint16Array,长度为 byteArray 的一半let shortArray = new Int16Array(byteArray.length / 2)//遍历 byteArray,将每两个字节合并成一个短整型for (let i = 0; i < byteArray.length; i += 2) {shortArray[i / 2] = (byteArray[i] & 0xFF) | (byteArray[i + 1] & 0xFF) << 8;}const step = 10;for (let i = 0; i < shortArray.length; i += step) {// console.log(i + "文件short值：" + shortArray[i])if (this.mWidth > 0 && this.dataArray.length >= this.mWidth) {this.dataArray.shift()}this.dataArray.push(shortArray[i])}this.isPlaying = truethis.draw2();this.index += 1;},stopPlayback() {console.log("停止播放-stopPlayback")this.isPlaying = falseclearInterval(this.drawIntervalId)const ctx = this.$refs.canvas.getContext('2d')ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height)this.drawGrid(ctx)},draw2() {if (!this.isPlaying) {return}// console.log('开始绘图-draw')const ctx = this.$refs.canvas.getContext('2d')ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height)this.drawGrid(ctx)this.drawWaveform(ctx)},drawGrid(ctx) {const { width, height } = ctx.canvasthis.mWidth = ctx.canvas.widththis.mHeight = ctx.canvas.heightctx.strokeStyle = '#ccc'ctx.lineWidth = 1for (let i = 0; i < height; i += 10) {ctx.beginPath()ctx.moveTo(0, i)ctx.lineTo(width, i)ctx.stroke()}for (let j = 0; j < width; j += 10) {ctx.beginPath()ctx.moveTo(j, 0)ctx.lineTo(j, height)ctx.stroke()}},drawWaveform(ctx) {ctx.beginPath()ctx.lineWidth = 1ctx.strokeStyle = '#25ebd7'let x = 0let len = this.dataArray.length;let index = this.mWidth - len;for (let i = index + 1; i < this.mWidth; i++) {const mCenterY = this.mHeight / 2;const y = mCenterY - (this.dataArray[i - index - 1] / (32768 / mCenterY));// console.log(`i=${i},position=${i - index - 1},,data=${this.dataArray[i - index - 1]},,y=${y},,mCenterY=${mCenterY}`)x = i - 1;ctx.lineTo(x, y)ctx.stroke()}},}
}
</script>