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queries; just search for this class in the ui.js file of WinJS and you’ll find it. Along the way, you’ll run into
one more set of WinRT APIs—perhaps the bottom of the hole!—that I wanted to mention before
wrapping up this subject: Windows.Storage.BulkAccess. These actually exist solely for use by
StorageDataSource and are not intended for direct use in apps. Even if you create your own data source
or collection control, it’s best to just use the enumeration and prefetch APIs we’ve already discussed, as
they give identical performance.
Here My Am! Update
To bring together some of the topics we’ve covered in this chapter, the companion content includes
another revision of the Here My Am! app with the following changes and additions (mostly to
pages/home/home.js unless noted):
• It now incorporates the Bing Maps SDK so that the control is part of the package rather than
loaded from a remote source. This eliminates the iframe we’ve been using to host the map, so all
the code from html/map.html can move into js/default.js. Note that to run this sample in Visual
Studio you need to download and install the SDK yourself.
• Instead of copying pictures taken with the camera to app data, those are now copied to a
HereMyAm folder in the Pictures library. The Pictures Library capability has been declared.
• Instead of saving a pathname to the last captured image file, which is used when the app is
terminated and restarted, the StorageFile is saved in Windows.Storage.AccessCache to
guarantee future programmatic access.
• An added appbar command allows you to use the File Picker to select an image to load instead
of relying solely on the camera. This also allows you to use a camera app, if desired. Note that we
use a particular settingsIdentifier with the picker in this case to distinguish from the picker for
recent images.
• Another appbar command allows you to choose from recent pictures from the camera. This
defaults to our folder in the Pictures library and uses a different settingsIdentifier.
• Additional commands for About, Help, and a Privacy Statement are included on the Settings
pane using the WinJS.Application.onsettings event (see js/default.js). The first two display
content from within the app whereas the third pulls down web content in an iframe; all the
settings pages are found in the html folder of the project.
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