前端水印的简单实现代码示例

<div class="wrap1 wrap_common"></div>

<style>
* {
  margin: 0; 
  padding: 0; 
}
.wrap_common {
  position: relative; 
  margin: 0 auto; 
  width: 800px; 
  height: 44vh; 
  border: 1px solid rgba(0, 0, 0, 1); 
  background: rgba(255, 255, 255, 1); 
  overflow: hidden; 
}
.wrap_common:first-child{
  margin-bottom: 5vh; 
}
</style>

const wrap = document.querySelector('.wrap1');
const { clientWidth, clientHeight } = wrap;
const waterHeight = 100;
const waterWidth = 180;
// 能放下几行几列
const [columns, rows] = [Math.ceil(clientWidth / waterWidth), Math.ceil(clientHeight / waterHeight)]
for (let i = 0; i < columns; i++) {
  for (let j = 0; j <= rows; j++) {
    // 生成水印块
    const watcerMarkElement = createWaterMarkElement();
    // 动态设置偏移值
    addAttributes(watcerMarkElement, {
      width: `${waterWidth}px` ,
      height: `${waterHeight}px` ,
      left: `${waterWidth + (i - 1) * waterWidth + 10}px` ,
      top: `${waterHeight + (j - 1) * waterHeight + 10}px` ,
    });
    wrap.appendChild(watcerMarkElement)
  }
}

const wrap = document. querySelector('. wrap2'); 
wrap.style.backgroundImage = `url(${drawWaterMark()})` ; 

const drawWaterMark = (text = '小豪看世界') => {
  const sin = Math.sin(Math.PI / 4.5);
  const cos = Math.cos(Math.PI / 4.5);
  const canvas = document.createElement('canvas')
  canvas.width = 200;
  canvas.height = 100;
  const ctx = canvas.getContext('2d');
  ctx.transform(cos, -sin, sin, cos, 0, 0);
  ctx.font = '16px';
  ctx.fillStyle = 'rgba(0,0,0,.4)';
  ctx.fillText(text, 80, 140);
  ctx.fillText(text, -30, 100);
  return canvas.toDataURL('image/png')
};

const style = document. createElement('style'); 
style.type = 'text/css'; 
style.innerHTML = `
  .wrap2 {
    background-image: url(${drawWaterMark()});
  }
`; 
document.body.appendChild(style);