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The Media Control UI
As mentioned in the previous section, providing handlers for the MediaControl object events is required
for background audio so that the user can control the audio through hardware buttons (built into many
devices, including keyboards and remote controls) without needing to switch to the app. This is
especially important because background audio continues to play not only when the user switches to
another app, but also when they switch to the Start screen switch to the desktop, or lock the device.
The default media control UI appears as shown in Figure 10-3 in the upper left of the screen,
regardless of what is on the screen at the time. Tapping the app name will switch to the app.
FIGURE 10-3 The media control UI appearing above the Start screen (left) and the desktop (right)
You can see in these images that the app’s Display Name from the manifest is what’s shown by
default in the UI. Although this is an acceptable fallback, audio apps should ideally provide richer audio
metadata to the MediaControl, specifically it’s albumArt, trackName, and artistName properties (the
latter two of which must be less than 128 characters). This is done in the Configure keys for media
sample, which demonstrates how to obtain album art for a track, a subject we’ll return to later.
With such metadata the media control UI will appear as follows; tapping the album art, track name
or artist name will switch back to the audio app.
You’ll notice in the images above that the forward and backward buttons are disabled. This is
because the app does not have listeners for the nexttrackpressed and previoustrackpressed events
of the MediaControl object; we’ll see how to use these in the next section. There are other events as well,
such as channeldownpressed, channeluppressed, fastforwardpressed, rewindpressed,
recordpressed, and stoppressed, though these aren’t represented in the media control UI.
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