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FIGURE 12-9 The Print-n-Go application.
registering the Print contract
Most of the magic required to print content in Windows 8 happens during the initial phase of an
application. In fact, after registering the Print contract during initialization, you're nearly all set. Note
that application initialization is only the preferred place where you could place the Print contract; you
could do that later in the application. All that really matters is that you must have the Print contract in
place before the user can invoke any printing functionality.
As usual for the exercises in this topic, you have an init method on the main application object.
Here's an implementation of the method that registers the Print contract:
printerApp.init = function () {
var printManager = Windows.Graphics.Printing.PrintManager;
var printView = printManager.getForCurrentView();
printView.onprinttaskrequested = function (eventArgs) {
var printTask = eventArgs.request.createPrintTask("Print-n-Go", function
(args) {
printTask.oncompleted = onPrintTaskCompleted;
function onPrintTaskCompleted(eventArgs) {
if (eventArgs.completion === Windows.Graphics.Printing.PrintTaskCompletion.
failed) {
printerApp.alert("Failed to print.");
Registering the Print contract essentially means invoking the getForCurrentView method on the
PrintManager system object. The returned view must be further configured with a handler for the
requested print task event. In other words, anytime a user requests a print task through the charms,
or anytime an app requests print services programmatically, the application must create a print task.
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