在canvas中，可以使用clip()函數裁切區域，設定裁切區域後，只有在區域內的影像才能顯示，其餘部分會被屏蔽掉。本文主要和大家介紹了canvas裁剪clip()函數的具體使用的相關資料,希望能幫助大家。
未使用裁切繪製一個圓形
<!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
##
<!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
使用clip()裁切區域
<!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
也可以使用arc繪製圓形的剪裁區域
<!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.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
##使用save和restore實現只裁切單一路徑
以上是canvas中使用clip()函數裁切法的詳細內容。更多資訊請關注PHP中文網其他相關文章！
