vue實現爲頁面加水印

主要實現邏輯是先創建一個所需水印的canvas圖片, 然後建一個div, 將canvas圖片作爲背景插入html

主要實現的方式是參考 https://www.jb51.net/article/221760.htm 感謝

1. 首先是創建一個js, 將水印的公共方法封裝一下

let watermark = {};
let setWatermark = (text, sourceBody) => {
    let id = 'watermark_fjq_' + parseInt(Math.random() * 100000);
    if (document.getElementById(id) !== null) {
        document.body.removeChild(document.getElementById(id));
    }
    //水印圖片
    let can = document.createElement('canvas');
    can.width = 150;// 單個水印大小
    can.height = 120;// 單個水印大小
    let cans = can.getContext('2d');
    cans.rotate(-20 * Math.PI / 180);
    cans.font = '15px Vedana';
    cans.fillStyle = '#DCDCDC';//水印顏色
    cans.textAlign = 'left';
    cans.textBaseline = 'Middle';
    cans.fillText(text, can.width / 20, can.height);
    //設置插入div樣式
    let water_div = document.createElement('div');
    water_div.id = id;
    water_div.style.pointerEvents = 'none';
    water_div.style.overflow = 'hidden';
    water_div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat';
    if (sourceBody) {
        sourceBody.style.position = 'relative';
        water_div.style.width = '100%';
        water_div.style.height = '100%';
        water_div.style.position = 'absolute';
        water_div.style.top = '0';
        water_div.style.left = '0';
        sourceBody.appendChild(water_div);
    } else {
        water_div.style.top = '3px';
        water_div.style.left = '0px';
        water_div.style.position = 'fixed';
        water_div.style.zIndex = '9999';
        water_div.style.width = document.documentElement.clientWidth + 'px';
        water_div.style.height = document.documentElement.clientHeight + 'px';
        document.body.appendChild(water_div);
    }
    return id;
}

/**
 *  該方法只允許調用一次
 *  @param:
 *  @text == 水印內容
 *  @sourceBody == 水印添加在哪裏，不傳就是body
 * */
watermark.set = (text, sourceBody) => {
    setTimeout(() => {
        setWatermark(text, sourceBody);
    }, 1000);//延遲加載
}

export default watermark;

2. 在需要的需要調用

import watermark from '@/lib/watermark.js';
watermark.set('水印文本',this.$refs.mkdiv);//某個div需要水印, 需要提前給div設置ref屬性
watermark.set('水印文本');//整個頁面需要水印

3. 查看效果