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用canvas画心电图的示例代码

2024-09-05 07:22:38
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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....最后到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++;             cc();             return;         }         if(y > hei/2){             if(reY >= y){                 reX = x;                 reY = y;                 i++;                 cc();                 return;             }         }else if(y < hei/2){             if(reY <= y){                 reX = x;                 reY = y;                 i++;                 cc();                 return;             }         }else{             reX = x;             reY = y;             i++;             cc();             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;             }         }         cc();     }    function cc(){        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>

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