vue实现一个pdf在线预览，pdf选择文本并提取复制文字触发弹窗效果

[TOC]

一、文件预览

1、安装依赖包

这里安装了disjs-dist@2.16版本，安装过程中报错缺少worker-loader

npm i pdfjs-dist@2.16.105 worker-loader@3.0.8

2、模板部分

<template>
  <div id="pdf-view">
    <canvas v-for="page in pdfPages" :key="page" :id="pdfCanvas" />
    <div id="text-view"></div>
  </div>
</template>

3、js部分（核心）

核心代码如下：

利用 PDF.getDocument获取pdf基础数据
通过canvas将pdf渲染到canvas画布上
<script> import * as pdfjsViewer from "pdfjs-dist/web/pdf_viewer.js"; import "pdfjs-dist/web/pdf_viewer.css"; import * as PDF from "pdfjs-dist/webpack";
export default {
name: "",
components: {},
data() {
return {
pdfPages: 1,
pdfPath: "http://localhost:8080/qfnext.pdf",
// 总页数
pdfPages: 1,
// 页面缩放
pdfScale: 1,
pdfDoc: null,
};
},
mounted() {
this.loadFile(this.pdfPath);
},
methods: {
loadFile(url) {
PDF.getDocument({
url,
cMapUrl: "https://cdn.jsdelivr.net/npm/pdfjs-dist@2.16.105/cmaps/",
cMapPacked: true,
}).promise.then((pdf) => {
this.pdfDoc = pdf;
// 获取pdf文件总页数
this.pdfPages = pdf.numPages;
this.$nextTick(() => {
this.renderPage(1); // 从第一页开始渲染
});
});
},
renderPage(num) {
this.pdfDoc.getPage(num).then((page) => {
const canvas = document.getElementById(pdfCanvas);
const ctx = canvas.getContext("2d");
const viewport = page.getViewport({ scale: this.pdfScale });
canvas.width = viewport.width;
canvas.height = viewport.height;
const renderContext = {
canvasContext: ctx,
viewport,
};
page.render(renderContext);
});
},
},
};
</script>

可能出现的问题：

(1) 页面文字可选中，但文本不可见

通过测试发现，将 pdfjs-dist/web/pdf_viewer.css 路径下的 color 属性注释后可显示文本。

.textLayer span,
.textLayer br {
  /* color: transparent; */
  position: absolute;
  white-space: pre;
  cursor: text;
  transform-origin: 0% 0%;
}

pdf多页面处理

模板处理id作为唯一标识
<canvas v-for="page in pdfPages" :key="page" :id="`page-${page}`" />
修改canvas渲染逻辑，主要通过递归的方式逐一渲染

renderPage(num) {
this.pdfDoc.getPage(num).then((page) => {
const canvas = document.getElementById(page-${num});
const ctx = canvas.getContext("2d");
const viewport = page.getViewport({ scale: this.pdfScale });
canvas.width = viewport.width;
canvas.height = viewport.height;
const renderContext = {
canvasContext: ctx,
viewport,
};
page.render(renderContext);
if (num < this.pdfPages) {
this.renderPage(num + 1);
}
});
},

二、文本选中与弹窗(核心代码)

   Promise.all([getTextContentPromise, renderPagePromise])
            .then(([textContent]) => {
              const textLayerDiv = document.createElement("div");
              // 注意：此处不要修改该元素的class名称，该元素的样式通过外部导入，名称是固定的
              textLayerDiv.setAttribute("class", "textLayer");
              // 设置容器样式
              textLayerDiv.setAttribute(
                "style",
                `
                  z-index: 1;
                  opacity: .2;
                  // background-color:#fff;
                  // transform: scale(1.1);
                  width: 100%,
                  height: 100%,
              `,
              );
              // 设置容器的位置和宽高
              textLayerDiv.style.left = canvas.offsetLeft + "px";
              textLayerDiv.style.top = canvas.offsetTop + "px";
              textLayerDiv.style.height = canvas.offsetHeight + "px";
              textLayerDiv.style.width = canvas.offsetWidth + "px";

              const textView = document.querySelector("#text-view");
              textView.appendChild(textLayerDiv);

              const textLayer = new TextLayerBuilder({
                // container: ,
                textLayerDiv: textLayerDiv,
                pageIndex: page.pageIndex,
                viewport: viewport,
                eventBus,
                // textDivs: []
              });

              textLayer.setTextContent(textContent);
              textLayer.render();
              // 当选择文本后鼠标取消点击时触发
              textLayerDiv.addEventListener("mouseup", () => {
                // // 隐藏文本层
                // textLayerDiv.style.display = 'none';
                // 是否选择了文本
                const isTextSelected =
                  window.getSelection().toString().trim() !== "";
                if (isTextSelected) {
                  //选择的文本内容
                  const selectedText = window.getSelection().toString();
                  console.log("Selected text:", selectedText);
                  if (selectedText) {
                    alert(selectedText);
                  }
                }
              });
            })
            .catch((error) => {
              console.error("Error rendering page:", error);
            });

三、完整代码如下

<template>
  <div id="pdf-view">
    <canvas v-for="page in pdfPages" :key="page" :id="`page-${page}`" />
    <div id="text-view"></div>
  </div>
</template>

<script>
  import * as pdfjsViewer from "pdfjs-dist/web/pdf_viewer.js";
  import "pdfjs-dist/web/pdf_viewer.css";
  import * as PDF from "pdfjs-dist/webpack";
  // import { getDocument } from 'pdfjs-dist/webpack';
  import { TextLayerBuilder } from "pdfjs-dist/web/pdf_viewer.js";
  const pdfjsWorker = import("pdfjs-dist/build/pdf.worker.entry");
  PDF.GlobalWorkerOptions.workerSrc = pdfjsWorker;
  const eventBus = new pdfjsViewer.EventBus();
  export default {
    name: "",
    components: {},
    data() {
      return {
        pdfPages: 1,
        pdfPath: "http://localhost:8080/qfnext.pdf",
        // 总页数
        pdfPages: 1,
        // 页面缩放
        pdfScale: 1,
        pdfDoc: null,
      };
    },
    mounted() {
      this.loadFile(this.pdfPath);
    },
    methods: {
      loadFile(url) {
        PDF.getDocument({
          url,
          cMapUrl: "https://cdn.jsdelivr.net/npm/pdfjs-dist@2.16.105/cmaps/",
          cMapPacked: true,
        }).promise.then((pdf) => {
          this.pdfDoc = pdf;
          // 获取pdf文件总页数
          this.pdfPages = pdf.numPages;
          this.$nextTick(() => {
            this.renderPage(1); // 从第一页开始渲染
          });
        });
      },
      renderPage(num) {
        this.pdfDoc.getPage(num).then((page) => {
          const canvas = document.getElementById(`page-${num}`);
          const ctx = canvas.getContext("2d");
          const viewport = page.getViewport({ scale: this.pdfScale });
          canvas.width = viewport.width;
          canvas.height = viewport.height;
          const renderContext = {
            canvasContext: ctx,
            viewport,
          };

          // 获取文本内容和渲染页面的 Promise
          const getTextContentPromise = page.getTextContent();
          const renderPagePromise = page.render(renderContext);
          if (num < this.pdfPages) {
            this.renderPage(num + 1);
          }
          Promise.all([getTextContentPromise, renderPagePromise])
            .then(([textContent]) => {
              const textLayerDiv = document.createElement("div");
              // 注意：此处不要修改该元素的class名称，该元素的样式通过外部导入，名称是固定的
              textLayerDiv.setAttribute("class", "textLayer");
              // 设置容器样式
              textLayerDiv.setAttribute(
                "style",
                `
                  z-index: 1;
                  opacity: .2;
                  // background-color:#fff;
                  // transform: scale(1.1);
                  width: 100%,
                  height: 100%,
              `,
              );
              // 设置容器的位置和宽高
              textLayerDiv.style.left = canvas.offsetLeft + "px";
              textLayerDiv.style.top = canvas.offsetTop + "px";
              textLayerDiv.style.height = canvas.offsetHeight + "px";
              textLayerDiv.style.width = canvas.offsetWidth + "px";

              const textView = document.querySelector("#text-view");
              textView.appendChild(textLayerDiv);

              const textLayer = new TextLayerBuilder({
                // container: ,
                textLayerDiv: textLayerDiv,
                pageIndex: page.pageIndex,
                viewport: viewport,
                eventBus,
                // textDivs: []
              });

              textLayer.setTextContent(textContent);
              textLayer.render();
              // 当选择文本后鼠标取消点击时触发
              textLayerDiv.addEventListener("mouseup", () => {
                // // 隐藏文本层
                // textLayerDiv.style.display = 'none';
                // 是否选择了文本
                const isTextSelected =
                  window.getSelection().toString().trim() !== "";
                if (isTextSelected) {
                  //选择的文本内容
                  const selectedText = window.getSelection().toString();
                  console.log("Selected text:", selectedText);
                  if (selectedText) {
                    alert(selectedText);
                  }
                }
              });
            })
            .catch((error) => {
              console.error("Error rendering page:", error);
            });
        });
      },
    },
  };
</script>
<style lang="scss" scoped>
  .pdf-con {
    border: 2px solid #ccc;
    width: 80%;
    margin: auto;
    height: 800px;
    overflow: auto;
    // display: none;
  }
</style>