Google Spreadsheet to pdf with watermark in Google script - google-apps-script

Question

I want to convert the spreadsheet with a watermark/background image, and send + save the generated pdf
The converting to pdf worked, but I don't know if/how you can put an image to the generated pdf.
This is what i got now:
function ExportAndSent(subject, filename, email) {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var message = "A message";
var tempSpreadsheet = SpreadsheetApp.create(filename);
var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
sheet = ss.getActiveSheet();
sheet.copyTo(tempSpreadsheet);
tempSpreadsheet.deleteActiveSheet();
var pdf = DriveApp.getFileById(tempSpreadsheet.getId()).getAs(MimeType.PDF);
var pdfBytes = pdf.getBytes();
var attach = {fileName:(filename + ".pdf"),content:pdfBytes, mimeType:MimeType.PDF};
// Here we need to put a watermark
// Send and export
MailApp.sendEmail(email, subject, message, {attachments:[attach]});
DriveApp.createFile(pdf);
// Delete Temporary
DriveApp.getFileById(tempSpreadsheet.getId()).setTrashed(true);
}

Answer 1

It looks like the spreadsheet is already converted to a PDF. A third party service can be used to add a watermark to open the PDF and add a watermark to it. PDF WebAPI is a free service you can use. Below I put together a function that can take in a PDF and add a watermark to it. The watermark is hardcoded to "watermark.jpg" currently, but that can be changed. From looking at the code above, the function should be called between the following lines:
var pdf = DriveApp.getFileById(tempSpreadsheet.getId()).getAs(MimeType.PDF);
var pdfBytes = pdf.getBytes();
The "pdf" variable should be used as input, and "pdfBytes", can take the return value of appendWatermark().
You will need to sign up for a free PDF WebAPI account to get an ID and key.
function appendWatermark(inputPDF) {
var fileBlob = inputPDF.copyBlob();
var decorationData = [{
"watermarkSettings": {
"opacity": 50,
"source": {
"file": "watermark.jpg",
"page": 1
},
"scale": {
"type": "relative",
"percent": 90
},
"location": "top",
"rotation": "0"
}
}];
var applicationData = {
"id": "",
"key": ""
};
var payload = {
"application": JSON.stringify(applicationData),
"input": fileBlob,
"decorationData": JSON.stringify(decorationData),
"resource": DriveApp.getFilesByName("watermark.jpg").next().getBlob()
};
var options = {
"method": "post",
"payload": payload
};
var response = UrlFetchApp.fetch("https://pdfprocess.datalogics.com/api/actions/decorate/document", options);
return response.getBytes;
}