vue 使用class建立和清除水印的示例程式碼
阿新 • • 發佈:2020-12-28
頁面新增水印的方法有很多,以下舉例使用class定義的方法進行水印內容渲染:
1、新建檔案:WatermarkClass.js
export default class WatermarkClass { constructor({id="watermarkID",str = "",fontSize = 18,width = 400,height = 400,fillStyle="#333333",opacity = 1 }) { this.id = id; this.str = str; this.fontSize = fontSize; this.width = width; this.height = height; this.fillStyle = fillStyle this.opacity = opacity; } // 繪製水印 draw() { if (document.getElementById(this.id) !== null) { document.body.removeChild(document.getElementById(this.id)); } const canvas = document.createElement("canvas"); // 設定canvas畫布大小 canvas.width = this.width; canvas.height = this.height; const ctx = canvas.getContext("2d"); ctx.rotate(-(15 * Math.PI) / 180); // 水印旋轉角度 ctx.font = `${this.fontSize}px Vedana`; ctx.fillStyle = this.fillStyle; ctx.textAlign = "center"; ctx.textBaseline = "middle"; this.str.split(",").forEach((item,index) => { ctx.fillText(item,canvas.width / 2,canvas.height / 2 + (index * this.fontSize + 10)); // 水印在畫布的位置x,y軸 }); const div = document.createElement("div"); div.id = this.id; div.style.pointerEvents = "none"; div.style.top = "30px"; div.style.left = "10px"; div.style.opacity = this.opacity; div.style.position = "fixed"; div.style.zIndex = "999999"; div.style.width = `${document.documentElement.clientWidth}px`; div.style.height = `${document.documentElement.clientHeight}px`; div.style.background = `url(${canvas.toDataURL("image/png")}) left top repeat`; document.body.appendChild(div); } setOptions({fontSize = 18,width = 300,height = 300,opacity = 1,str = ""}) { this.fontSize = fontSize; this.width = width; this.height = height; this.fillStyle = fillStyle this.opacity = opacity; this.str = str; this.draw(); } // 繪製 render() { this.draw(); window.onresize = () => { this.draw(); }; } // 移除水印 removeWatermark() { if (document.getElementById(this.id) !== null) { document.body.removeChild(document.getElementById(this.id)); } } }
2、在頁面種引入使用:
import watermarkClass from "@/libs/watermarkClass"; export default { name: "App",mounted: function () { this.initWatermark() },methods: { initWatermark() { // 方法一 let watermark = new watermarkClass({ id: "watermarkID",str: "紫藤蘿-watermarkClass",fontSize: 20,width: 300,height: 200,fillStyle: "#dddddd",opacity: 0.4,}); watermark.render(); // 5秒後,清除水印 setTimeout(() => { watermark.removeWatermark(); },5000); } },};
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