清除矩形区域 context.clearRect(x,y,width,height)
x:清除矩形起点横坐标
y:清除矩形起点纵坐标
width:清除矩形长度
height:清除矩形高度
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>huatu</title>
<style>
body{
background: #dddddd;
}
#canvas{
margin: 10px;
background: #ffffff;
border: thin inset #aaaaaa;
}
</style>
</head>
<body>
<canvas id="canvas" width="600" height="400">
Canvas not Supported
</canvas>
<script>
var canvas=document.getElementById('canvas'),
context=canvas.getContext('2d');
context.lineJoin='round';
context.lineWidth=30;
context.font='24px Helvetica';
context.fillText('Click anywhere to erase',175,40);
context.strokeRect(75,100,200,200);
context.fillRect(325,100,200,200);
context.canvas.onmousedown = function(e) {
context.clearRect(0,0,600,400);
}
</script>
</body>
</html>