| <html> |
| <head> |
| <meta charset="UTF-8"> |
| <title>Previous/Next example</title> |
| </head> |
| <body> |
|
|
| <h1>'Previous/Next' example</h1> |
|
|
| <div> |
| <button id="prev">Previous</button> |
| <button id="next">Next</button> |
| |
| <span>Page: <span id="page_num"></span> / <span id="page_count"></span></span> |
| </div> |
|
|
| <div> |
| <canvas id="the-canvas" style="border: 1px solid black; direction: ltr;"></canvas> |
| </div> |
|
|
| <script src="../../node_modules/pdfjs-dist/build/pdf.js"></script> |
|
|
| <script id="script"> |
| // |
| // If absolute URL from the remote server is provided, configure the CORS |
| // header on that server. |
| // |
| var url = '../../web/compressed.tracemonkey-pldi-09.pdf'; |
|
|
| // |
| // In cases when the pdf.worker.js is located at the different folder than the |
| // PDF.js's one, or the PDF.js is executed via eval(), the workerSrc property |
| // shall be specified. |
| // |
| pdfjsLib.GlobalWorkerOptions.workerSrc = |
| '../../node_modules/pdfjs-dist/build/pdf.worker.js'; |
|
|
| var pdfDoc = null, |
| pageNum = 1, |
| pageRendering = false, |
| pageNumPending = null, |
| scale = 0.8, |
| canvas = document.getElementById('the-canvas'), |
| ctx = canvas.getContext('2d'); |
|
|
| /** |
| * Get page info from document, resize canvas accordingly, and render page. |
| * @param num Page number. |
| */ |
| function renderPage(num) { |
| pageRendering = true; |
| // Using promise to fetch the page |
| pdfDoc.getPage(num).then(function(page) { |
| var viewport = page.getViewport({ scale: scale, }); |
| canvas.height = viewport.height; |
| canvas.width = viewport.width; |
|
|
| // Render PDF page into canvas context |
| var renderContext = { |
| canvasContext: ctx, |
| viewport: viewport, |
| }; |
| var renderTask = page.render(renderContext); |
|
|
| // Wait for rendering to finish |
| renderTask.promise.then(function () { |
| pageRendering = false; |
| if (pageNumPending !== null) { |
| // New page rendering is pending |
| renderPage(pageNumPending); |
| pageNumPending = null; |
| } |
| }); |
| }); |
|
|
| // Update page counters |
| document.getElementById('page_num').textContent = num; |
| } |
|
|
| /** |
| * If another page rendering in progress, waits until the rendering is |
| * finised. Otherwise, executes rendering immediately. |
| */ |
| function queueRenderPage(num) { |
| if (pageRendering) { |
| pageNumPending = num; |
| } else { |
| renderPage(num); |
| } |
| } |
|
|
| /** |
| * Displays previous page. |
| */ |
| function onPrevPage() { |
| if (pageNum <= 1) { |
| return; |
| } |
| pageNum--; |
| queueRenderPage(pageNum); |
| } |
| document.getElementById('prev').addEventListener('click', onPrevPage); |
|
|
| /** |
| * Displays next page. |
| */ |
| function onNextPage() { |
| if (pageNum >= pdfDoc.numPages) { |
| return; |
| } |
| pageNum++; |
| queueRenderPage(pageNum); |
| } |
| document.getElementById('next').addEventListener('click', onNextPage); |
|
|
| /** |
| * Asynchronously downloads PDF. |
| */ |
| var loadingTask = pdfjsLib.getDocument(url); |
| loadingTask.promise.then(function(pdfDoc_) { |
| pdfDoc = pdfDoc_; |
| document.getElementById('page_count').textContent = pdfDoc.numPages; |
|
|
| // Initial/first page rendering |
| renderPage(pageNum); |
| }); |
| </script> |
|
|
| </body> |
| </html> |
