Saving image to Spreadsheet with Google Scripts

Question

I'm trying to add a signature pad to a Google Sheet using jSignature. I've added a dialog box that records the signature like this:

//Code.gs
function showDialog() {
  var html = HtmlService.createHtmlOutputFromFile('Page')
    .setWidth(400)
    .setHeight(300);
DocumentApp.getUi()
  .showModalDialog(html, 'Your Signature is Required');
}

//Page.html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdn.rawgit.com/willowsystems/jSignature/master/libs/jSignature.min.js"></script>

Please draw your signature on the signature pad below: 

<div id="signature"></div>

<img id="rendered" src="">

<script>
  $("#signature").jSignature({
    'background-color': 'transparent',
    'decor-color': 'transparent'
  });

  function renderSignature(){
    $("img#rendered").attr("src",$('#signature').jSignature('getData','default'));
  }
</script>

<input type="button" value="Render" onclick="renderSignature();"/>
<input type="button" value="Add to Sheet" onclick="//What to do"/>
<input type="button" value="Close" onclick="google.script.host.close()" />

The only thing is I can't figure out how to get the image into a cell. Copy/paste won't work, it would need to be inserted as far as I can tell. I was thinking maybe I write a function to save it to Google Drive and then insert it using a URL, but I still can't figure out how to grab the actual image in order to do anything with it. Any insight appreciated, I'm new to GS.

Answer 1

To the save the image to your Drive you can do something like this

Your Html Code:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdn.rawgit.com/willowsystems/jSignature/master/libs/jSignature.min.js"></script>

Please draw your signature on the signature pad below: 

<div id="signature"></div>

<img id="rendered" src="">

<script>
  $("#signature").jSignature({
    'background-color': 'transparent',
    'decor-color': 'transparent'
  });

  function renderSignature(){
    $("img#rendered").attr("src",$('#signature').jSignature('getData','default'));
  }

  function saveImage(){ //This sends the image src to saveImages function
  var bytes = document.getElementById('rendered').src
  console.log(bytes)
  google.script.run.saveImage(bytes)
  }
</script>

<input type="button" value="Render" onclick="renderSignature();"/>
<input type="button" value="Add to Sheet" onclick="saveImage()"/>
<input type="button" value="Close" onclick="google.script.host.close()" />

Server side code:

function showDialog() {
  var html = HtmlService.createHtmlOutputFromFile('Sign')
    .setWidth(400)
    .setHeight(300);
SpreadsheetApp.getUi()
  .showModalDialog(html, 'Your Signature is Required');
}

function saveImage(bytes){
  var bytes = bytes.split(",")
  var blob = Utilities.newBlob(Utilities.base64Decode(bytes[1]), 'image/png');
  blob.setName("Sign Pic")
  DriveApp.getFolderById("Folder ID to save SignPic").createFile(blob)
}

You will have to keep track of names of image files and insert the pics into the spreadsheet accordingly.