MICROSOFT_PRESS_EBOOK_PROGRAMMING_WINDOWS_8_APPS_WITH_HTML_CSS_AND_JAVASCRIPT_PDF

For example, the Music app that comes with Windows 8 allows you create a new playlist when you’re
viewing tracks of some album. The following commands appear on the app bar (left), and when you
select New Playlist, a flyout appears (middle) requesting the name, after which the flyout appears on the
app bar (right):
The playlist then appears within the app as another album. In other words, though playlists might be
saved in discrete files, they aren’t necessarily presented that way to the user, and the API reflects that
usage pattern.
Loading a playlist uses the Playlist.loadAsync method given a StorageFile for the playlist. This
might be a StorageFile obtained from a file picker or from the enumeration of the app’s private playlist
folder. Scenario 2 of the Playlist sample (display.js) demonstrates the former, where it then goes through
each file and requests their music properties:
function displayPlaylist() {
var picker = new Windows.Storage.Pickers.FileOpenPicker();
picker.suggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.musicLibrary;
picker.fileTypeFilter.replaceAll(SdkSample.playlistExtensions);
var promiseCount = 0;
picker.pickSingleFileAsync()
.then(function (item) {
if (item) {
return Windows.Media.Playlists.Playlist.loadAsync(item);
}
return WinJS.Promise.wrapError("No file picked.");
})
.then(function (playlist) {
SdkSample.playlist = playlist;
var promises = {};
// Request music properties for each file in the playlist.
playlist.files.forEach(function (file) {
promises[promiseCount++] = file.properties.getMusicPropertiesAsync();
});
// Print the music properties for each file. Due to the asynchronous
// nature of the call to retrieve music properties, the data may appear
// in an order different than the one specified in the original playlist.
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