CODEWITHSUNDEEP
javascriptgoogle-apps-scriptblob
EvSunWoodard
EvSunWoodard

Reputation: 1280

How to pass a blob in a .run function

I can't find the answer in the Google Apps Script Reference, so I'm asking: Can you pass a blob through a .run() function in a google script. My code is as follows.

This is my HTML file's script. All the HTML contains is a object. And a

to make "print" statements. 

<script>
  var canvas = document.getElementById('myCanvas');
  var can = canvas.getContext("2d");
  can.fillRect(20,20,150,100);
  var canvasData = canvas.toDataURL('image/png', 1);
  var blob = toBlob(canvasData);

  document.getElementById('ins').innerHTML = "Got the Blob  " + blob.type;
  google.script.run.printCanvas(blob);


  function toBlob(dataURI) {

    // convert base64 to raw binary data held in a string
    // doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
    document.getElementById('ins').innerHTML = ("Data URI:" + dataURI);

    var byteString = atob(dataURI.split(',')[1]);

    // separate out the mime component
    var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0]

    // write the bytes of the string to an ArrayBuffer
    var ab = new ArrayBuffer(byteString.length);
    var ia = new Uint8Array(ab);
    for (var i = 0; i < byteString.length; i++) {
        ia[i] = byteString.charCodeAt(i);
    }

    // write the ArrayBuffer to a blob, and you're done
    var blob = new Blob([ab], {type: 'image/png'});

    return blob;
  }

</script>

The "print" of blob.type, gives me "Got the Blob image/png"

However, the app won't execute the .run(blob), error code:

"Uncaught TypeError: Failed due to illegal value in property: 0"

I know that GAS won't pass DIVs, so I was wondering if it is just impossible to pass a blob to the .gs file. I can't figure out why else the application won't run. If it is possible, tell me how, please.

I know it's not an the .gs side, because the first line of the .gs is a DocumentApp.alert, which doesn't pop. So, the application is not reaching the .gs file.

Upvotes: 3

Views: 2215

Answers (1)

EvSunWoodard
EvSunWoodard

Reputation: 1280

So, thank you to Sandy Good. The answer is in-fact, NO. It is impossible to send a blob to the .gs page as described.

However, you can encode your blob into base-64 encoded string,

https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsDataURL

And then decode it in the .gs file with Utilities.base64Decode(base64encodedstring);

Upvotes: 1

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