<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>簽名</title>
<style type="text/css">
*{
margin: 0;
padding: 0;
}
body{
background: gray;
}
#test{
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
margin: auto;
background:white;
}
</style>
</head>
<body>
<canvas id="test" width="500" height="500"></canvas>
</body>
<script type="text/javascript">
window.onload=function(){
var canvas =document.getElementById("test");
if(canvas.getContext){
var ctx = canvas.getContext("2d");
}
canvas.onmousedown=function(ev){
ev = ev || window.event;
if(canvas.setCapture){
canvas.setCapture();
}
ctx.beginPath()
ctx.moveTo(ev.clientX - canvas.offsetLeft, ev.clientY - canvas.offsetTop)
document.onmousemove=function(ev){
ctx.save()
ctx.strokeStyle = 'green'
ctx.lineWidth = 12
ev = ev || event;
ctx.lineTo(ev.clientX - canvas.offsetLeft, ev.clientY - canvas.offsetTop)
ctx.stroke()
ctx.restore()
}
document.onmouseup=function(){
document.onmousemove=document.onmouseup=null;
if(document.releaseCapture){
document.releaseCapture();
}
}
return false;
}
}
</script>
</html>
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