VUE项目处理PDF文档流数据并实现PDF的预览以及打印功能以及处理PDF打印乱码问题
1.业务需求：
- vue项目需要对后端返回的PDF文档流数据进行处理，在前端实现处理后的PDF文件的预览以及打印功能，最后再处理PDF页面打印乱码问题。
2.需求分析：
- 首先由于后端返回的是文档流数据，所以第一步要将文档流数据转换为正确的PDF格式的数据，第二步是要将转化的PDF数据在页面上进行预览（这里我使用的是vue-pdf插件），最后是要在预览的PDF页面上添加打印按钮以及实现打印功能（PDF打印功能vue-pdf插件里面有方法提供，不用再单独去引入外部的打印插件）。另外由于vue-pdf插件使用的是iframe进行渲染，所以存在乱码问题，所以需要对其源文件进行修改。
3.解决方案：
- 第1步是处理后端返回的文档流数据（注意：请求PDF文档流数据的接口时如果是axios封装的post请求注意使用
params,{responseType:'blob'}，如果是axios封装的get请求注意使用{params:params,responseType:'blob'}，否则文档流解析会报错，或者解析出来是一片空白）：
// 将返回的流数据转换为url（data: 文档流数据）
getObjectURL(data) {
let url = null
let file = new Blob([data],{type:'application/pdf;chartset=utf-8'})
if (window.createObjectURL != undefined) {
// 通用
url = window.createObjectURL(file)
} else if (window.webkitURL != undefined) {
// 兼容谷歌
try {
url = window.webkitURL.createObjectURL(file)
} catch (error) {
}
} else if (window.URL != undefined) {
// 兼容其他
try {
url = window.URL.createObjectURL(file)
} catch (error) {
}
}
// 将转化后url赋值
this.pdfUrl = url
},- 第2步是下载及引入vue-pdf：
// 首先是安装vue-pdf
npm install --save vue-pdf// 在页面引入
import pdf from 'vue-pdf'
components: {
pdf,
},- 第3步是将转化好的PDF数据通过vue-pdf插件进行预览及打印：
<div v-if="src" style="overflow-y: auto;overflow-x: hidden;">
<!--打印直接调用vue-pdf里面的方法-->
<el-button type="primary" @click="$refs.pdf.print()" size="mini">打印</el-button>
<el-button type="warning" plain @click="viewDia = false" size="mini">关闭</el-button>
<div>
<pdf
ref="pdf"
:src="pdfUrl"
></pdf>
</div>
</div>- 第四部是处理PDF打印乱码问题：
- 详情可参考
https://github.com/FranckFreiburger/vue-pdf/pull/130/commits/253f6186ff0676abf9277786087dda8d95dd8ea7 - 解决方法是修改pdfjsWrapper.js文件
（索引：node_modules => vue-pdf => src => pdfjsWrapper.js） - 最后附上我这边最新的修改的pdfjsWrapper.js全部内容（亲测无误，可直接复制）：
import { PDFLinkService } from 'pdfjs-dist/es5/web/pdf_viewer';
var pendingOperation = Promise.resolve();
export default function(PDFJS) {
function isPDFDocumentLoadingTask(obj) {
return typeof(obj) === 'object' && obj !== null && obj.__PDFDocumentLoadingTask === true;
// or: return obj.constructor.name === 'PDFDocumentLoadingTask';
}
function createLoadingTask(src, options) {
var source;
if ( typeof(src) === 'string' )
source = { url: src };
else if ( src instanceof Uint8Array )
source = { data: src };
else if ( typeof(src) === 'object' && src !== null )
source = Object.assign({}, src);
else
throw new TypeError('invalid src type');
// source.verbosity = PDFJS.VerbosityLevel.INFOS;
// source.pdfBug = true;
// source.stopAtErrors = true;
var loadingTask = PDFJS.getDocument(source);
loadingTask.__PDFDocumentLoadingTask = true; // since PDFDocumentLoadingTask is not public
if ( options && options.onPassword )
loadingTask.onPassword = options.onPassword;
if ( options && options.onProgress )
loadingTask.onProgress = options.onProgress;
return loadingTask;
}
function PDFJSWrapper(canvasElt, annotationLayerElt, emitEvent) {
var pdfDoc = null;
var pdfPage = null;
var pdfRender = null;
var canceling = false;
canvasElt.getContext('2d').save();
function clearCanvas() {
canvasElt.getContext('2d').clearRect(0, 0, canvasElt.width, canvasElt.height);
}
function clearAnnotations() {
while ( annotationLayerElt.firstChild )
annotationLayerElt.removeChild(annotationLayerElt.firstChild);
}
this.destroy = function() {
if ( pdfDoc === null )
return;
// Aborts all network requests and destroys worker.
pendingOperation = pdfDoc.destroy();
pdfDoc = null;
}
this.getResolutionScale = function() {
return canvasElt.offsetWidth / canvasElt.width;
}
this.printPage = function(dpi, pageNumberOnly) {
if ( pdfPage === null )
return;
// 1in == 72pt
// 1in == 96px
var PRINT_RESOLUTION = dpi === undefined ? 150 : dpi;
var PRINT_UNITS = PRINT_RESOLUTION / 72.0;
var CSS_UNITS = 96.0 / 72.0;
// var iframeElt = document.createElement('iframe');
var printContainerElement = document.createElement('div');
printContainerElement.setAttribute('id', 'print-container')
// function removeIframe() {
//
// iframeElt.parentNode.removeChild(iframeElt);
// }
function removePrintContainer() {
printContainerElement.parentNode.removeChild(printContainerElement);
}
new Promise(function(resolve, reject) {
// iframeElt.frameBorder = '0';
// iframeElt.scrolling = 'no';
// iframeElt.width = '0px;'
// iframeElt.height = '0px;'
// iframeElt.style.cssText = 'position: absolute; top: 0; left: 0';
//
// iframeElt.onload = function() {
//
// resolve(this.contentWindow);
// }
//
// window.document.body.appendChild(iframeElt);
printContainerElement.frameBorder = '0';
printContainerElement.scrolling = 'no';
printContainerElement.width = '0px;'
printContainerElement.height = '0px;'
printContainerElement.style.cssText = 'position: absolute; top: 0; left: 0';
window.document.body.appendChild(printContainerElement);
resolve(window)
})
.then(function(win) {
win.document.title = '';
return pdfDoc.getPage(1)
.then(function(page) {
var viewport = page.getViewport({ scale: 1 });
// win.document.head.appendChild(win.document.createElement('style')).textContent =
printContainerElement.appendChild(win.document.createElement('style')).textContent =
'@supports ((size:A4) and (size:1pt 1pt)) {' +
'@page { margin: 1pt; size: ' + ((viewport.width * PRINT_UNITS) / CSS_UNITS) + 'pt ' + ((viewport.height * PRINT_UNITS) / CSS_UNITS) + 'pt; }' +
'}' +
'#print-canvas { display: none }' +
'@media print {' +
'body { margin: 0 }' +
// 'canvas { page-break-before: avoid; page-break-after: always; page-break-inside: avoid }' +
'#print-canvas { page-break-before: avoid; page-break-after: always; page-break-inside: avoid; display: block }' +
'body > *:not(#print-container) { display: none; }' +
'}'+
'@media screen {' +
'body { margin: 0 }' +
'}'
return win;
})
})
.then(function(win) {
var allPages = [];
for ( var pageNumber = 1; pageNumber <= pdfDoc.numPages; ++pageNumber ) {
if ( pageNumberOnly !== undefined && pageNumberOnly.indexOf(pageNumber) === -1 )
continue;
allPages.push(
pdfDoc.getPage(pageNumber)
.then(function(page) {
var viewport = page.getViewport({ scale: 1 });
// var printCanvasElt = win.document.body.appendChild(win.document.createElement('canvas'));
var printCanvasElt = printContainerElement.appendChild(win.document.createElement('canvas'));
printCanvasElt.setAttribute('id', 'print-canvas')
printCanvasElt.width = (viewport.width * PRINT_UNITS);
printCanvasElt.height = (viewport.height * PRINT_UNITS);
return page.render({
canvasContext: printCanvasElt.getContext('2d'),
transform: [ // Additional transform, applied just before viewport transform.
PRINT_UNITS, 0, 0,
PRINT_UNITS, 0, 0
],
viewport: viewport,
intent: 'print'
}).promise;
})
);
}
Promise.all(allPages)
.then(function() {
win.focus(); // Required for IE
if (win.document.queryCommandSupported('print')) {
win.document.execCommand('print', false, null);
} else {
win.print();
}
// removeIframe();
removePrintContainer();
})
.catch(function(err) {
// removeIframe();
removePrintContainer();
emitEvent('error', err);
})
})
}
this.renderPage = function(rotate) {
if ( pdfRender !== null ) {
if ( canceling )
return;
canceling = true;
pdfRender.cancel();
return;
}
if ( pdfPage === null )
return;
var pageRotate = (pdfPage.rotate === undefined ? 0 : pdfPage.rotate) + (rotate === undefined ? 0 : rotate);
var scale = canvasElt.offsetWidth / pdfPage.getViewport({ scale: 1 }).width * (window.devicePixelRatio || 1);
var viewport = pdfPage.getViewport({ scale: scale, rotation:pageRotate });
emitEvent('page-size', viewport.width, viewport.height, scale);
canvasElt.width = viewport.width;
canvasElt.height = viewport.height;
pdfRender = pdfPage.render({
canvasContext: canvasElt.getContext('2d'),
viewport: viewport
});
annotationLayerElt.style.visibility = 'hidden';
clearAnnotations();
var viewer = {
scrollPageIntoView: function(params) {
emitEvent('link-clicked', params.pageNumber)
},
};
var linkService = new PDFLinkService();
linkService.setDocument(pdfDoc);
linkService.setViewer(viewer);
pendingOperation = pendingOperation.then(function() {
var getAnnotationsOperation =
pdfPage.getAnnotations({ intent: 'display' })
.then(function(annotations) {
PDFJS.AnnotationLayer.render({
viewport: viewport.clone({ dontFlip: true }),
div: annotationLayerElt,
annotations: annotations,
page: pdfPage,
linkService: linkService,
renderInteractiveForms: false
});
});
var pdfRenderOperation =
pdfRender.promise
.then(function() {
annotationLayerElt.style.visibility = '';
canceling = false;
pdfRender = null;
})
.catch(function(err) {
pdfRender = null;
if ( err instanceof PDFJS.RenderingCancelledException ) {
canceling = false;
this.renderPage(rotate);
return;
}
emitEvent('error', err);
}.bind(this))
return Promise.all([getAnnotationsOperation, pdfRenderOperation]);
}.bind(this));
}
this.forEachPage = function(pageCallback) {
var numPages = pdfDoc.numPages;
(function next(pageNum) {
pdfDoc.getPage(pageNum)
.then(pageCallback)
.then(function() {
if ( ++pageNum <= numPages )
next(pageNum);
})
})(1);
}
this.loadPage = function(pageNumber, rotate) {
pdfPage = null;
if ( pdfDoc === null )
return;
pendingOperation = pendingOperation.then(function() {
return pdfDoc.getPage(pageNumber);
})
.then(function(page) {
pdfPage = page;
this.renderPage(rotate);
emitEvent('page-loaded', page.pageNumber);
}.bind(this))
.catch(function(err) {
clearCanvas();
clearAnnotations();
emitEvent('error', err);
});
}
this.loadDocument = function(src) {
pdfDoc = null;
pdfPage = null;
emitEvent('num-pages', undefined);
if ( !src ) {
canvasElt.removeAttribute('width');
canvasElt.removeAttribute('height');
clearAnnotations();
return;
}
// wait for pending operation ends
pendingOperation = pendingOperation.then(function() {
var loadingTask;
if ( isPDFDocumentLoadingTask(src) ) {
if ( src.destroyed ) {
emitEvent('error', new Error('loadingTask has been destroyed'));
return
}
loadingTask = src;
} else {
loadingTask = createLoadingTask(src, {
onPassword: function(updatePassword, reason) {
var reasonStr;
switch (reason) {
case PDFJS.PasswordResponses.NEED_PASSWORD:
reasonStr = 'NEED_PASSWORD';
break;
case PDFJS.PasswordResponses.INCORRECT_PASSWORD:
reasonStr = 'INCORRECT_PASSWORD';
break;
}
emitEvent('password', updatePassword, reasonStr);
},
onProgress: function(status) {
var ratio = status.loaded / status.total;
emitEvent('progress', Math.min(ratio, 1));
}
});
}
return loadingTask.promise;
})
.then(function(pdf) {
pdfDoc = pdf;
emitEvent('num-pages', pdf.numPages);
emitEvent('loaded');
})
.catch(function(err) {
clearCanvas();
clearAnnotations();
emitEvent('error', err);
})
}
annotationLayerElt.style.transformOrigin = '0 0';
}
return {
createLoadingTask: createLoadingTask,
PDFJSWrapper: PDFJSWrapper,
}
}.then(function(pdf) {
pdfDoc = pdf;
emitEvent('num-pages', pdf.numPages);
emitEvent('loaded');
})
.catch(function(err) {
clearCanvas();
clearAnnotations();
emitEvent('error', err);
})
}
annotationLayerElt.style.transformOrigin = '0 0';
}
return {
createLoadingTask: createLoadingTask,
PDFJSWrapper: PDFJSWrapper,
}
}- 统一说明：最近有码友反馈修改pdfjsWrapper.js不生效，这里大家注意一下vue-pdf版本不要太高了，参考我使用的4.2.0版本，不然会有问题。
- 解决
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