主页 / 建站知识 /

用canvas画心电图的示例代码

建站知识 2021-07-02 23:00www.168986.cn长沙网站建设

本文介绍了用canvas画心电图的示例代码，分享给大家，具体如下

效果图

思路

​1.模拟点（如果你有真实的数据，那就是把数据幻化成canvas对应的坐标点）

​ 模拟点时注意的点就是高起部分需要对称以及为了好看要随机出现上上下下

2.画线

​ 画线需要注意有一个匀速移动的过程。

​ 比如 A点到B点，不是简单的A画到B，而是A点到A1,A2....到B（这一块按照比例移动比较难）

3.画线的一些效果，比如加上阴影（这里就可以自由发挥了）具体代码

<!DOCTYPE html>
 <html lang="en">
 <head>
     <meta charset="UTF-8">
     <title>心电图</title>
     <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
     <style>
         html,body{
             width: 100%;
             height: 100%;
             margin: 0;
         }
         canvas{
             background: #000;
             width: 100%;
            height: 100%;
         }
     </style>
 </head>
 <body>
 <div id="canvas">
     <canvas id="can"></canvas>
 </div>
 <script>
     var can = document.getElementById('can'),
         pan,
         index = 0,
         flag = true,
         wid = document.body.clientWidth,
         hei = document.body.clientHeight,
         x = 0,
         y = hei/2,
         drawX = 0, 
         drawY = hei/2,
         drawXY = [],
         cDrawX = 0,
         i = 0,
         reX = 0,
         reY = 0;
     start();
     function start(){
         can.height = hei;
         can.width  = wid;
         pan = can.getContext("2d");
         pan.strokeStyle = "white";
         pan.lineJoin = "round";
         pan.lineWidth = 6;
         pan.shadowColor = "#228DFF";
         pan.shadowOffsetX = 0;
         pan.shadowOffsetY = 0;
         pan.shadowBlur = 20;
         pan.beginPath();
         pan.moveTo(x,y);
         drawXYS();
         index = setInterval(move,1);
     };

     function drawXYS(){
         if(drawX > wid){
         }else{
             if(drawY == hei/2){
                 if(flag){
                     flag = false;
                 }else{
                     var _y = Math.ceil(Math.random()10);
                     _y = _y/2;
                     if(Number.isInteger(_y)){
                         drawY += Math.random()180+30;
                     }else{
                         drawY -= Math.random()180+30;
                     }
                     flag = true;
                 }
                 cDrawX = Math.random()40+15;
             }else{
                 drawY = hei/2;
             }
             drawX += cDrawX;
             drawXY.push({
                 x : drawX,
                 y : drawY
             });
             drawXYS();
         }
     }

     function move(){
         var x = drawXY[i].x,
             y = drawXY[i].y;
         if(reX >= x - 1){
             reX = x;
             reY = y;
             i++;
             ();
             return;
         }
         if(y > hei/2){
             if(reY >= y){
                 reX = x;
                 reY = y;
                 i++;
                 ();
                 return;
             }
         }else if(y < hei/2){
             if(reY <= y){
                 reX = x;
                 reY = y;
                 i++;
                 ();
                 return;
             }
         }else{
             reX = x;
             reY = y;
             i++;
             ();
             return;
         }

         reX += 1;
         if(y == hei/2){
             reY = hei/2;
         }else{
             var c = Math.abs((drawXY[i].x-drawXY[i-1].x)/(drawXY[i].y-drawXY[i-1].y));
             var _yt = (reX-drawXY[i-1].x)/c;

             if(drawXY[i].y < drawXY[i-1].y){
                 reY = drawXY[i-1].y - _yt;
             }else{
                 reY = drawXY[i-1].y + _yt;
             }
         }
         ();
     }

    function (){
        if(i == drawXY.length){
             pan.closePath();
             clearInterval(index);
             index = 0;
             x = 0;
             y = hei/2;
             flag = true;
             i = 0;
         }else{
             pan.lineTo(reX, reY);
             pan.stroke();
         }
    }
 
</script>
</body>
</html>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持狼蚁SEO。

上一篇：html5 figure和figcaption的使用方法 下一篇：Html5 canvas实现粒子时钟的示例代码

长沙网站设计

Copyright © 2016-2025 www.168986.cn 狼蚁网络 版权所有 Power by