98 lines
3.8 KiB
JavaScript
98 lines
3.8 KiB
JavaScript
// Minimal PDF rendering and text-selection example using PDF.js by Vivin Suresh Paliath (http://vivin.net)
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// This example uses a built version of PDF.js that contains all modules that it requires.
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//
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// The problem with understanding text selection was that the text selection code has heavily intertwined
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// with viewer.html and viewer.js. I have extracted the parts I need out of viewer.js into a separate file
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// which contains the bare minimum required to implement text selection. The key component is TextLayerBuilder,
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// which is the object that handles the creation of text-selection divs. I have added this code as an external
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// resource.
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//
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// This demo uses a PDF that only has one page. You can render other pages if you wish, but the focus here is
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// just to show you how you can render a PDF with text selection. Hence the code only loads up one page.
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//
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// The CSS used here is also very important since it sets up the CSS for the text layer divs overlays that
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// you actually end up selecting.
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//
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// NOTE: The original example was changed to remove jQuery usage, re-structure and add more comments.
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window.onload = function () {
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if (typeof PDFJS === 'undefined') {
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alert('Built version of pdf.js is not found\nPlease run `node make generic`');
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return;
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}
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var scale = 1.5; //Set this to whatever you want. This is basically the "zoom" factor for the PDF.
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PDFJS.workerSrc = '../../build/generic/build/pdf.worker.js';
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function loadPdf(pdfPath) {
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var pdf = PDFJS.getDocument(pdfPath);
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return pdf.then(renderPdf);
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}
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function renderPdf(pdf) {
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return pdf.getPage(1).then(renderPage);
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}
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function renderPage(page) {
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var viewport = page.getViewport(scale);
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// Create and append the 'pdf-page' div to the pdf container.
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var pdfPage = document.createElement('div');
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pdfPage.className = 'pdfPage';
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var pdfContainer = document.getElementById('pdfContainer');
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pdfContainer.appendChild(pdfPage);
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// Set the canvas height and width to the height and width of the viewport.
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var canvas = document.createElement('canvas');
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var context = canvas.getContext('2d');
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// The following few lines of code set up scaling on the context, if we are
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// on a HiDPI display.
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var outputScale = getOutputScale(context);
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canvas.width = (Math.floor(viewport.width) * outputScale.sx) | 0;
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canvas.height = (Math.floor(viewport.height) * outputScale.sy) | 0;
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context._scaleX = outputScale.sx;
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context._scaleY = outputScale.sy;
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if (outputScale.scaled) {
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context.scale(outputScale.sx, outputScale.sy);
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}
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// The page, canvas and text layer elements will have the same size.
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canvas.style.width = Math.floor(viewport.width) + 'px';
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canvas.style.height = Math.floor(viewport.height) + 'px';
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pdfPage.style.width = canvas.style.width;
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pdfPage.style.height = canvas.style.height;
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pdfPage.appendChild(canvas);
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var textLayerDiv = document.createElement('div');
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textLayerDiv.className = 'textLayer';
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textLayerDiv.style.width = canvas.style.width;
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textLayerDiv.style.height = canvas.style.height;
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pdfPage.appendChild(textLayerDiv);
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// Painting the canvas...
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var renderContext = {
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canvasContext: context,
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viewport: viewport
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};
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var renderTask = page.render(renderContext);
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// ... and at the same time, getting the text and creating the text layer.
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var textLayerPromise = page.getTextContent().then(function (textContent) {
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var textLayerBuilder = new TextLayerBuilder({
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textLayerDiv: textLayerDiv,
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viewport: viewport,
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pageIndex: 0
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});
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textLayerBuilder.setTextContent(textContent);
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});
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// We might be interested when rendering complete and text layer is built.
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return Promise.all([renderTask.promise, textLayerPromise]);
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}
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loadPdf('pdf/TestDocument.pdf');
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};
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