MICROSOFT_PRESS_EBOOK_PROGRAMMING_WINDOWS_8_APPS_WITH_HTML_CSS_AND_JAVASCRIPT_PDF

var images = iFrame.contentDocument.documentElement.getElementsByTagName("img");
if (images.length > 0) {
shareOperation.data.getResourceMapAsync().done(function (resourceMap) {
if (resourceMap.size > 0) {
for (var i = 0, len = images.length; i < len; i++) {
var streamReference = resourceMap[images[i].getAttribute("src")];
if (streamReference) {
// Call a helper function to map the image element's src
// to a corresponding blob URL generated from the streamReference
setResourceMapURL(streamReference, images[i]);
}
}
}
});
}
The setResourceMapURL helper function does pretty much what the bitmap-specific code did, which
is call openReadAsync on the stream, call MSApp.createBlobFromRandomAccessStream, pass that blob to
URL.createObjectURL, set the img.src with the result, and close the stream.
After the target app has completed a sharing operation, it should call the ShareOperation.report-
Completed method, as shown earlier with the template code. This lets the system know that the data
package has been consumed, the share flow is complete, and all related resources can be released. The
share target sample does this when you explicitly click a button for this purpose, but normally you
automatically call the method whenever you’ve completed the share. Do be aware that calling
reportCompleted will close the target app’s sharing UI, so avoid calling it as soon as the target activates:
you want the user to feel confident that the operation was carried out.
Long-Running Operations
When you run the share target sample and invoke the Share charm from a suitable source app, there’s a
little expansion control near the bottom labeled “Long-running Share support.” If you expand that,
you’ll see some additional controls and a bunch of descriptive text, as shown in Figure 12-6. The buttons
shown here tie into a number of other methods on the ShareOperation object alongside
reportCompleted. These help Windows understand exactly how the share operation is happening within
the target: reportStarted, reportDataRetrieved, reportSubmittedBackgroundTask, and reportError. As
you can see from the descriptions in Figure 12-6, these generally relate to telling Windows when the
target app has finished cooking its meal, so to speak, and the system can clean the dishes and put away
the utensils:
• reportStarted informs Windows that your sharing operation might take a while, as if you’re
uploading the data from the package to another place, or just sending an email attachment with
what ends up being large images and such. This specific method indicates that you’ve obtained
all necessary user input and that the share pane can be dismissed.
• reportDataRetrieved informs Windows that you’ve extracted what you need from the data
package such that it can be released. If you’ve called MSApp.createBlobFromRandomAccessStream
for an image stream, for example, the blob now contains a copy of the image that’s local to the
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