该代码可在Arkts 与 前端使用，基于canvas
仓库地址：https://gitee.com/harmony_os_example/harmony-os-ecg-waveform.git
代码中的list数组为波形数据，该示例需要根据自己业务替换绘制频率，波形数据，ecg原始数据生成x,y轴值等
相关代码：
@Entry
@Component
struct Index {@StorageProp('windowWidth') windowWidth: number = 1125;private readonly settings_bg: RenderingContextSettings = new RenderingContextSettings(true);private readonly ctx_bg: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings_bg);private readonly settings: RenderingContextSettings = new RenderingContextSettings(true);private readonly ctx: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings);@State drawFrequency: number = 256; // 绘制频率@State list: number[] =[-0.057600000000000005, -0.0544, -0.05040000000000001, -0.0456, -0.0408, -0.0352, -0.030400000000000003, -0.0256,-0.020800000000000003, -0.016, -0.011200000000000002, -0.007200000000000001, -0.0032, -0.0008, 0.0016, 0.0032,0.0048, 0.005600000000000001, 0.0048, 0.0032, 0.0008, -0.0024, -0.0064, -0.011200000000000002, -0.016,-0.020800000000000003, -0.024800000000000003, -0.028, -0.0296, -0.0296, -0.028, -0.024800000000000003,-0.020800000000000003, -0.016800000000000002, -0.0136, -0.0128, 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0.42240000000000005, 0.3944,0.3632000000000001, 0.328, 0.29040000000000005, 0.2504, 0.2104, 0.16960000000000003, 0.12880000000000005,0.08880000000000002, 0.0488, 0.011200000000000002, -0.024, -0.057600000000000005, -0.0904, -0.12,-0.14720000000000005, -0.172, -0.1944, -0.2128, -0.2304, -0.2448, -0.2584, -0.2696, -0.2792, -0.2872, -0.2928,-0.29760000000000003, -0.3, -0.30160000000000003, -0.3008, -0.2992, -0.296, -0.292, -0.28800000000000003,-0.28240000000000004, -0.2776, -0.2712, -0.264, -0.256, -0.248, -0.2392, -0.2304, -0.2208, -0.21120000000000003,-0.20160000000000003, -0.1936, -0.1856, -0.1784, -0.172, -0.1648, -0.1592, -0.1536, -0.148, -0.1424,-0.1368]; // 绘制数据@State drawList: number[] = [];@State originalData: number[] = []; // 原始数据@State ecgPlay: boolean = false;@State times: number = 0;@State lastX: number | null = null;@State lastY: number | null = null;@State drawIndex: number = 0;@State canvasWidth: number = 375;@State canvasHeight: number = 201;@State averageGridWidth: number = 30;@State gridWidth: number = 6;@State maxGridWidth: number = 151;startDraw() {this.drawCurve();this.drawList = [...this.list]}resetDraw() {this.lastX = null;this.lastY = null;this.drawIndex = 0;this.drawList = [...this.list];clearInterval(this.times)this.ctx.clearRect(0, 0, this.canvasWidth, this.canvasHeight)}aboutToAppear(): void {this.canvasWidth = Math.ceil(px2vp(this.windowWidth))}// 播放完成，重置数据resetPlay() {this.ecgPlay = false;this.lastX = null;this.lastY = null;this.drawIndex = 0;this.drawList = [...this.list]}drawCurve() {let list: number[] = this.drawList;if (list.length === 0) {this.ecgPlay = false;return}let screenPointCount = (2 * this.drawFrequency) + (this.drawFrequency * (1 / 5)) // 屏幕点的数量let pointWidth = (this.canvasWidth - 24) / screenPointCount; // 每一个点的宽度// 256 频率let interval = (1000 / this.drawFrequency) * 4;// 定时器this.times = setInterval(() => {let arr: number[] = list.splice(0, 4);if (arr.length === 0) {clearInterval(this.times);this.resetPlay();this.resetDraw();return}this.ctx.fillStyle = 'rgba(0, 0, 0, 0)';this.ctx.clearRect(((this.drawIndex + 4) * pointWidth) + 24, 0, (4 * pointWidth) + 10,this.canvasHeight - 20)this.ctx.fillRect(((this.drawIndex + 4) * pointWidth) + 24, 0, (4 * pointWidth) + 10,this.canvasHeight - 20);for (let i = 0; i < arr.length; i++) {this.drawIndex = this.drawIndex + 1;let x = (this.drawIndex * pointWidth) + 24;let y = ((this.canvasHeight - 20) / 3) * 2 - arr[i] * 10 * this.gridWidth;if (y > this.canvasHeight - 20) {y = this.canvasHeight - 21;} else if (y <= 0) {y = 0;} else {y = y;}if (this.drawIndex >= screenPointCount) {this.ctx.clearRect(24, 0, 10, this.canvasHeight)this.drawIndex = 0;this.lastX = null; // 关键：清除上一个点，防止错误连接this.lastY = null;continue;}this.ctx.strokeStyle = "#000000";this.ctx.lineWidth = 1.5;if (this.lastX === null || this.lastY === null) {// 记录第一个点，不进行绘制this.lastX = x;this.lastY = y;continue;}this.ctx.beginPath();this.ctx.moveTo(this.lastX, this.lastY); // 从上一个点开始this.ctx.lineTo(x, y); // 连接到当前点this.ctx.stroke();this.ctx.closePath();// 更新上一个点的坐标this.lastX = x;this.lastY = y;}}, interval);}// 网格drawGrid() {// 绘制小网格x轴this.ctx_bg.beginPath();this.ctx_bg.strokeStyle = '#f1bdc3';this.ctx_bg.lineWidth = 0.5;for (let i = 24; i <= this.canvasWidth - 20; i += this.gridWidth) {if (i >= 24) {this.ctx_bg.moveTo(i, 0);this.ctx_bg.lineTo(i, this.canvasHeight - 20);}}this.ctx_bg.stroke();this.ctx_bg.closePath();// 绘制小网格轴y轴this.ctx_bg.beginPath();this.ctx_bg.strokeStyle = '#f1bdc3';this.ctx_bg.lineWidth = 0.5;for (let i = 0; i <= this.canvasHeight - 20; i += this.gridWidth) {this.ctx_bg.moveTo(24, i);this.ctx_bg.lineTo(this.canvasWidth, i);}this.ctx_bg.stroke();this.ctx_bg.closePath();// 绘制中网格x轴this.ctx_bg.beginPath();this.ctx_bg.strokeStyle = '#cd0a20';this.ctx_bg.lineWidth = 0.5;for (let i = 24; i <= this.canvasWidth; i += this.averageGridWidth) {if (i >= 24) {this.ctx_bg.moveTo(i, 0);this.ctx_bg.lineTo(i, this.canvasHeight - 20);}}this.ctx_bg.stroke();this.ctx_bg.closePath();// 绘制中网格y轴this.ctx_bg.beginPath();this.ctx_bg.strokeStyle = '#cd0a20';this.ctx_bg.lineWidth = 0.5;for (let i = 0; i <= this.canvasHeight - 20; i += this.averageGridWidth) {this.ctx_bg.moveTo(24, i);this.ctx_bg.lineTo(this.canvasWidth, i);}this.ctx_bg.stroke();this.ctx_bg.closePath();// 绘制x轴大网格线this.ctx_bg.beginPath();this.ctx_bg.strokeStyle = '#cd0a20';this.ctx_bg.lineWidth = 1;this.ctx_bg.font = '12vp sans-serif'for (let i = 24; i <= this.canvasWidth; i += this.maxGridWidth) {if (i >= 24) {this.ctx_bg.moveTo(i, 0);this.ctx_bg.lineTo(i, this.canvasHeight - 20);}}this.ctx_bg.stroke();this.ctx_bg.closePath();}build() {Column() {Row() {Column() {Canvas(this.ctx_bg).width(`100%`).height(`210vp`).position({ left: 0, top: 0 }).onReady(() => {this.drawGrid();// this.drawCurve();});Canvas(this.ctx).width(`100%`).height(`210vp`).position({ left: 0, top: 0 }).onReady(() => {});}.width(`100%`).height(`210vp`).backgroundColor(Color.White)}.width('100%').height(`210vp`).backgroundColor(0xDCDCDC)Row() {Button(this.ecgPlay ? '结束绘制' : '开始绘制').width('201vp').height('50vp').backgroundColor(Color.Black).type(ButtonType.Normal).borderRadius('12vp').onClick(() => {this.startDraw();})}}.width('100%').height('100%').backgroundColor("#f6f6f6")}
}
