This is an explanation of the video content.
 用技术延续对ACG的热爱
...
46
 | 
Js实现使用canvas生成水印图片用于元素背景，提升性能 

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #kok {
            width: 100%;
            height: 100vh;
        }
    </style>
</head>

<body>
    <div id="kok"></div>
    <script>
        function generateWatermarkImage(text, targetElementId, rotation = 0) {
            // 创建一个Canvas元素
            var canvas = document.createElement('canvas');
            var context = canvas.getContext('2d');

            // 设置Canvas的尺寸
            canvas.width = 300;
            canvas.height = 150;

            // 绘制水印文本
            context.font = '20px Arial';
            context.fillStyle = 'rgba(0, 0, 0, 0.2)';
            context.textAlign = 'center';
            context.textBaseline = 'middle';

            // 旋转水印
            context.translate(canvas.width / 2, canvas.height / 2);
            context.rotate((rotation * Math.PI) / 180);
            context.fillText(text, 0, 0);

            // 将Canvas转换为DataURL
            var dataURL = canvas.toDataURL('image/png');

            // 设置目标元素的背景图
            var targetElement = document.getElementById(targetElementId);
            targetElement.style.backgroundImage = 'url(' + dataURL + ')';
        }

        // 示例用法，将水印旋转45度
        generateWatermarkImage('watermark', 'kok', -45);
    </script>
</body>

</html>


46 前端 ↦ 前端JavaScript开发技巧 __ 119 字
 前端JavaScript开发技巧 #9