在canvas中，可以使用clip()函數(shù)裁剪區(qū)域，設(shè)定裁剪區(qū)域后，只有在區(qū)域內(nèi)的圖像才能顯示，其余部分會(huì)被屏蔽掉
未使用裁剪繪制一個(gè)圓
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
*{margin:0; padding:0;}
html, body{width:100%; height:100%; overflow:hidden; background-color:#AFAFAF;}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d');
canvas.width = document.body.clientWidth;
canvas.height = document.body.clientHeight;
context.lineWidth = 3;
context.strokeStyle = 'red';
context.beginPath();
context.arc(200, 200, 100, (Math.PI / 180) * 0, (Math.PI / 180) * 360, false);
context.stroke();
context.closePath();
</script>
</body>
</html>
效果
使用clip()裁剪區(qū)域
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
*{margin:0; padding:0;}
html, body{width:100%; height:100%; overflow:hidden; background-color:#AFAFAF;}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d');
canvas.width = document.body.clientWidth;
canvas.height = document.body.clientHeight;
context.lineWidth = 3;
context.strokeStyle = 'red';
context.rect(0, 0, 200, 200);
context.clip();
context.beginPath();
context.arc(200, 200, 100, (Math.PI / 180) * 0, (Math.PI / 180) * 360, false);
context.stroke();
context.closePath();
</script>
</body>
</html>
效果
也可以使用arc繪制圓形的剪裁區(qū)域
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
*{margin:0; padding:0;}
html, body{width:100%; height:100%; overflow:hidden; background-color:#AFAFAF;}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d');
canvas.width = document.body.clientWidth;
canvas.height = document.body.clientHeight;
context.lineWidth = 3;
context.strokeStyle = 'red';
context.arc(100, 100, 150, (Math.PI / 180) * 0, (Math.PI / 180) * 360, false);
context.clip();
context.beginPath();
context.arc(200, 200, 100, (Math.PI / 180) * 0, (Math.PI / 180) * 360, false);
context.stroke();
context.closePath();
</script>
</body>
</html>
效果
使用save和restore實(shí)現(xiàn)只裁剪單個(gè)路徑
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
*{margin:0; padding:0;}
html, body{width:100%; height:100%; overflow:hidden; background-color:#AFAFAF;}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d');
canvas.width = document.body.clientWidth;
canvas.height = document.body.clientHeight;
context.lineWidth = 3;
context.strokeStyle = 'red';
context.save();
context.rect(0, 0, 200, 200);
context.clip();
context.beginPath();
context.arc(200, 200, 100, (Math.PI / 180) * 0, (Math.PI / 180) * 360, false);
context.stroke();
context.closePath();
context.restore();
context.beginPath();
context.arc(250, 250, 100, (Math.PI / 180) * 0, (Math.PI / 180) * 360, false);
context.stroke();
context.closePath();
</script>
</body>
</html>
效果
以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。
