title: How to load an existing pdf and print using printing in flutter
body: <p>I've been been trying to print an existing pdf file which is in sd card. 
  So i added <strong>printing</strong> package to my flutter project to print pdf files.</p>
  
  <p><a href="https://pub.dev/packages/printing/versions/1.0.6" rel="nofollow noreferrer">Printing package link</a></p>
  
  <p>I checked their documentation and i can't find a way to load and print pdf.</p>
  
  <p>Fyi, i can create a pdf from image, text or whaetever it is and pass it to the Printing function. That works as anticipated. </p>
  
  <pre><code>final pdf = Document();
  
  pdf.addPage(Page(
        pageFormat: PdfPageFormat.a4,
        build: (Context context) {
          return Center(
            child: Text("Hello World"),
          );
        })
  );
  
  await Printing.layoutPdf(onLayout: (PdfPageFormat format) async =&gt; pdf.save());
  </code></pre>
  
  <p>Any help to load existing pdf and print would be appreciable</p>
  
  <p>Thanks</p>