How do you use getHtmlPrintDocumentSourceAsync to print in HTML/JavaScript Windows Store apps? - windows-runtime

Question

I am very simply trying to print some content in a Windows 10 app (Universal) using HTML and JavaScript/WinJS.
ALL of the documentation says that there is a function on MSApp called getHtmlPrintDocumentSource.
I do not have this, nor can I seem to find any relevant source to see if it may have been moved. I instead have getHtmlPrintDocumentSourceAsync. This seems to be a replacement for the former, but I cannot get it to work and there is zero documentation on it as far as I can tell.
When I run the below code (which is based on the documentation but updated to be async):
function onPrintTaskRequested(printEvent) {
var printTask = printEvent.request.createPrintTask("Print Sample", function (args) {
MSApp.getHtmlPrintDocumentSourceAsync(document)
.then(function(result) {
args.setSource(result);
});
printTask.oncompleted = onPrintTaskCompleted;
});
}
result is populated with some of the print settings as I would expect, but the content property is set to 0, which I am guessing is the problem. I can't really be sure as there is no documentation for this function. I can't even run any of the dozens of pieces of example code in the documentation using `getHtmlPrintDocumentSource' because it seemingly doesn't exist anymore.
In addition to just sending document to the Async method, I have tried a couple of different variations of creating document fragments. Same results.
Probably not terribly helpful, but the message in the Windows Print Dialog that opens when executing the above code is: "Nothing was sent to print. Open a document and print again."
Any ideas?

Answer 1

getHtmlPrintDocumentSource is a synchronous deprecated API in Windows 10 apps. We'll work on some of the docs left behind for Windows 8 and 8.1 to clarify that.
Check out https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/Printing/js for an example of how to use getHtmlPrintDocumentSourceAsync in JavaScript.
Here is the code:
// Needs to be invoked before calling the print API
function registerForPrintContract() {
var printManager = Windows.Graphics.Printing.PrintManager.getForCurrentView();
printManager.onprinttaskrequested = onPrintTaskRequested;
console.log("Print Contract registered. Use the Print button to print.", "sample", "status");
}
// Variable to hold the document source to print
var gHtmlPrintDocumentSource = null;
// Print event handler for printing via the PrintManager API.
function onPrintTaskRequested(printEvent) {
var printTask = printEvent.request.createPrintTask("Print Sample", function (args) {
args.setSource(gHtmlPrintDocumentSource);
// Register the handler for print task completion event
printTask.oncompleted = onPrintTaskCompleted;
});
}
// Print Task event handler is invoked when the print job is completed.
function onPrintTaskCompleted(printTaskCompletionEvent) {
// Notify the user about the failure
if (printTaskCompletionEvent.completion === Windows.Graphics.Printing.PrintTaskCompletion.failed) {
console.log("Failed to print.", "sample", "error");
}
}
// Executed just before printing.
var beforePrint = function () {
// Replace with code to be executed just before printing the current document:
};
// Executed immediately after printing.
var afterPrint = function () {
// Replace with code to be executed immediately after printing the current document:
};
function printButtonHandler() {
// Optionally, functions to be executed immediately before and after printing can be configured as following:
window.document.body.onbeforeprint = beforePrint;
window.document.body.onafterprint = afterPrint;
// Get document source to print
MSApp.getHtmlPrintDocumentSourceAsync(document).then(function (htmlPrintDocumentSource) {
gHtmlPrintDocumentSource = htmlPrintDocumentSource;
// If the print contract is registered, the print experience is invoked.
Windows.Graphics.Printing.PrintManager.showPrintUIAsync();
});
}