Load RTL PDF in Region

Two years ago I'v written a post about Displaying PDF in APEX but when I saw a blog post from Adrian Png  I'll try to use this method with a little changing and also to add two Next/Previous Buttons.


Demo application : OAC

Download sample application : APEX-LOADRTL-PDF


First Step we must add a CDN js via Cloudflare like below image and next we write codes in "Function and global variable Declaration"

File URLs:

//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.0.550/pdf.min.js

Function and global variable Declaration:

// If absolute URL from the remote server is provided, configure the CORS
// header on that server.
var url = '';
var pdfDoc = null,
    pageNum = 1,
    pageRendering = false,
    pageNumPending = null,
    scale = 1.5,
    canvas = document.getElementById('preview-pdfpane'),
    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);
    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);

Tip: When we set Right-To-Left in Globalization cause to have wrong displaying spatially for Persian PDF so I have a workaround for this issue, we can set "Direction : ltr"

Right-To_Left

Issue for Displaying

Page Inline:

#region-pdf{
    direction: ltr;
}

Solve issue

Now we create a region "Load PDF" and set this source code for adding a button in order to load PDF file.

<div>
  <a class="t-Button t-Button--icon t-Button--large t-Button--iconRight btn-preview-pdf" href="javascript:void(0);" type="button" id="B4">
        <span class="t-Icon fa fa-arrow-circle-right fa-anim-horizontal-shake"></span>    
        <span class="t-Icon t-Icon--left fa fa-newspaper-o" aria-hidden="true"></span>
<span class="t-Button-label">View PDF</span>
<span class="t-Icon t-Icon--right fa fa-newspaper-o" aria-hidden="true"></span></a>
</div>

In this sample we add a sub region under "Load PDF" region and change "Title" according below code , next add a source code

<span>صفحه: <span id="page_num"></span> / <span id="page_count"></span></span>
<canvas id="preview-pdfpane" ></canvas>

We set Static ID of region that used for example "region-pdf"

Under the sub region we add two buttons in order to implement "NEXT/Previous" of pages.

Previous Button:

Next Button:

So, we add two Dynamic Action on page 5 {Page Load & Preview PDF). 

Step by Step we add some true Actions.(Below Images are clear and we don't need to explain about each image)

Page Load:
we want to hide the Buttons and region when page loads.

1)

2)

3) 

JQuery Selector: #region-pdf_heading     (statisc_id + "_heading")

Page Load:
we want to show the Buttons and region when click on the button.

1)

var Url = 'https://......./test.pdf';
/**
 * Asynchronously downloads PDF.
 */
pdfjsLib.getDocument(Url).then(function(pdf) {
  pdfDoc = pdf;
  document.getElementById('page_count').textContent = pdfDoc.numPages;
  // Initial/first page rendering
  renderPage(1);
});

2)

3)

4)

JQuery Selector: #region-pdf_heading     (statisc_id + "_heading")

Enjoy it.