给图片添加自定义水印并下载

<template><div class="wrap"><div class="optea"><div class="file-upload"><p>选择图片</p><el-button type="text" style="color: #c00;"><label for="uploads"><i class="el-icon-upload2" style="margin-right: 5px;"></i>选择需要添加水印的图片</label></el-button><inputtype="file"id="uploads"hiddenaccept="image/png, image/jpeg, image/gif, image/jpg"@change="uploadImg($event, 1)"/></div><p>水印文字</p><el-inputv-model="watermarkOptions.text"placeholder="请输入水印内容"></el-input><p>字体颜色</p><el-color-picker v-model="watermarkOptions.color"></el-color-picker><p>旋转角度</p><el-sliderv-model="watermarkOptions.rotate":min="0":max="360"></el-slider><p>透明度</p><el-sliderv-model="watermarkOptions.alpha":min="0":max="100"></el-slider><p>文本间距</p><el-sliderv-model="watermarkOptions.width":min="0":max="100"></el-slider><p>字体大小</p><el-sliderv-model="watermarkOptions.fontSize":min="0":step="0.5":max="50"></el-slider></div><div><el-button@click="handleDown"class="download-btn"type="primary"plainicon="el-icon-download">下载水印图片</el-button><div class="preview" ref="previewImg"><img :src="preImg || defaultimg" alt="" /><div class="watermark" :style="{ background: paint }"></div></div></div></div>
</template>
<script>
/* eslint-disable */
import defaultimg from "@/assets/img/headPortrait.jpg";
import DomToImage from "dom-to-image";
export default {data() {return {defaultimg,preImg: "",watermarkOptions: {text: "仅供 xxx 验证使用",fontSize: 10,width: 5,color: "#000000",alpha: 35,rotate: 35}};},methods: {uploadImg(e, num) {//上传图片// this.option.imgvar file = e.target.files[0];if (!/\.(gif|jpg|jpeg|png|bmp|GIF|JPG|PNG)$/.test(e.target.value)) {alert("图片类型必须是.gif,jpeg,jpg,png,bmp中的一种");return false;}var reader = new FileReader();reader.onload = e => {let data;if (typeof e.target.result === "object") {// 把Array Buffer转化为blob 如果是base64不需要data = window.URL.createObjectURL(new Blob([e.target.result]));} else {data = e.target.result;}if (num === 1) {this.preImg = data;}};// 转化为base64reader.readAsDataURL(file);// 转化为blob// reader.readAsArrayBuffer(file)},handleDown() {let node = this.$refs.previewImg;let that = this;DomToImage.toPng(node).then(function(dataUrl) {var oLink = document.createElement("a");oLink.download = "水印图片.png";oLink.href = dataUrl;oLink.click();that.$nextTick(() => {that.$message.success("水印图片下载成功");});}).catch(function(error) {console.error("oops, something went wrong!", error);that.$message.error("下载失败");});}},computed: {paint() {// 文字长度const wordWidth =this.watermarkOptions.fontSize *this.watermarkOptions.text.split("").length;const width = wordWidth + this.watermarkOptions.width;let svgText = `<svg xmlns="http://www.w3.org/2000/svg" width="${width}px" height="${width}px"><text x="50%" y="50%"alignment-baseline="middle"text-anchor="middle"stroke="${this.watermarkOptions.color}"opacity="${this.watermarkOptions.alpha / 100}"transform="translate(${width / 2}, ${width / 2}) rotate(${this.watermarkOptions.rotate}) translate(-${width / 2}, -${width / 2})"font-weight="100"font-size="${this.watermarkOptions.fontSize}"font-family="microsoft yahe">${this.watermarkOptions.text}</text></svg>`;return `url(data:image/svg+xml;base64,${btoa(unescape(encodeURIComponent(svgText)))})`;}}
};
</script><style lang="scss" scoped>
.wrap {padding: 10px 20px;display: flex;justify-content: flex-start;align-items: center;p {margin: 5px 0;margin-bottom: 10px;font-weight: 600;}.download-btn {margin: 0 15px 15px;}.optea {width: 500px;}.preview {position: relative;margin-left: 20px;min-width: 750px;img {width: 100%;height: 100%;}.watermark {position: absolute;left: 0;top: 0;width: 100%;height: 100%;}}
}
</style>