通过canvas合成图片

效果图

页面布局部分

两个图片以及一个canvas画布

<img src="https://qnlite.gtimg.com/qqnewslite/20190924/avatar/head1.png" alt="" id="bg-img">
<img src="http://thirdwx.qlogo.cn/mmopen/vi_32/Q0j4TwGTfTLFPJR06vhs1iccMd3hFzJ3GXAFm4VljTErIq6ejH3ZicIvfz9DqKxecXkKlUsZtDYYXOo9h0icQWZDw/0" alt="" id="avatar">
<canvas id="my-canvas" width="" height=""></canvas>

JavaScript代码部分

<script src="https://code.jquery.com/jquery-3.4.1.min.js" ></script>
<script type="text/javascript">
    // 获取图片及画板对象
    var border_img = document.getElementById("border-img");
    var avatar = document.getElementById("avatar");
    var ca = document.getElementById("my-canvas");

	// 创建二维画布，并设置宽高
    var ctx = ca.getContext('2d');
    ca.width = 200;
    ca.height = 200;

	// 在画布 (0, 0) 位置作为起点绘制两张图片实现合成
    ctx.drawImage(avatar, 0, 0, 200, 200);
    ctx.drawImage(border_img, 0, 0, 200, 200);

	// 得到图片的Base64编码
    dataurl = ca.toDataURL();
</script>

代码合总

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>通过canvas合成图片</title>
	</head>
	<body>
		<img crossorigin="Anonymous" src="https://qnlite.gtimg.com/qqnewslite/20190924/avatar/head1.png" alt="" id="border-img">
		<img crossorigin="Anonymous" src="http://thirdwx.qlogo.cn/mmopen/vi_32/Q0j4TwGTfTLFPJR06vhs1iccMd3hFzJ3GXAFm4VljTErIq6ejH3ZicIvfz9DqKxecXkKlUsZtDYYXOo9h0icQWZDw/0" alt="" id="avatar">
		<hr>
		<canvas id="my-canvas" width="" height=""></canvas>
		<img src="" id="base64-img">
		
		<script src="https://code.jquery.com/jquery-3.4.1.min.js" ></script>
		<script type="text/javascript">
			var border_img = document.getElementById("border-img");
			var avatar = document.getElementById("avatar");
			
			var ca = document.getElementById("my-canvas");
			var ctx = ca.getContext('2d');
			ca.width = 200;
			ca.height = 200;
			ctx.drawImage(avatar, 0, 0, 200, 200);
			ctx.drawImage(border_img, 0, 0, 200, 200);
			dataurl = ca.toDataURL();
			$('#base64-img').attr('src', dataurl);
		</script>
	</body>
</html>