本文介紹了用canvas畫心電圖的示例代碼，分享給大家，具體如下：
效果圖：
思路：
?1.模擬點(diǎn)（如果你有真實(shí)的數(shù)據(jù)，那就是把數(shù)據(jù)幻化成canvas對應(yīng)的坐標(biāo)點(diǎn)）
? 模擬點(diǎn)時注意的點(diǎn)就是高起部分需要對稱以及為了好看要隨機(jī)出現(xiàn)上上下下
2.畫線
? 畫線需要注意有一個勻速移動的過程。
? 比如 A點(diǎn)到B點(diǎn)，不是簡單的A畫到B，而是A點(diǎn)到A1,A2....最后到B（這一塊按照比例移動比較難）
3.畫線的一些效果，比如加上陰影（這里就可以自由發(fā)揮了）具體代碼
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>心電圖</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>以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持VeVb武林網(wǎng)。
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