這篇文章帶給大家的內容是關於如何使用html5 canvas實現心電圖的移動效果，有一定的參考價值，有需要的朋友可以參考一下，希望對你有幫助。
1、模擬點（如果你有真實的數據，那就是把資料幻化成canvas對應的座標點）
模擬點時注意的點就是高起部分需要對稱以及為了好看要隨機出現上上下下
2、畫線
畫線需要注意有勻速移動的過程。
例如A點到B點，不是簡單的A畫到B，而是A點到A1,A2....最後到B（這一塊按照比例移動比較難）
#3、畫線的一些效果，例如加上陰影（這裡就可以自由發揮了）
<!DOCTYPE html>
<html>
<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>
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