title: How can I detect where to stamp an image in PDF with javascript
body: <p>Hello</p>
  
  <p>I'm trying to implement a little project that allow me to sign a PDF document, I already implement an Html 5 pad to draw the signature and get the Image to stamp into the pdf.
  I'm using the <strong>signature_pad</strong> library from <strong>Github</strong>:</p>
  
  <pre><code>var canvas = document.querySelector("canvas");
  var signaturePad = new SignaturePad(canvas);
  signaturePad.toDataURL(); // save image as PNG
  signaturePad.toDataURL("image/jpeg"); // save image as JPEG
  signaturePad.fromDataURL("data:image/png;base64,iVBORw0K...");
  signaturePad.clear();
  signaturePad.isEmpty();
  signaturePad.off();
  signaturePad.on();
  </code></pre>
  
  <p>My big problem is how can I know the place where the user have to stamp the signature into the pdf, because the pdf it is not the same, user could upload it's own pdf.</p>
  
  <p>Could anyone help me with any orientation about this, I really appreciate your help.</p>
  
  <p></p>