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CHAPTER 13: Android Service Class and Threads: Background Processing 493

2. Set these with “Turn Audio On” and “Turn Audio Off” data values, as
   shown in Figure 13-9. When the sight impaired access the playAudio or
   stopAudioImageView UI elements used for the audio control icons, they will
   hear these phrases from the Android voice synthesizer, informing them what
   these UI elements are for.

Figure 13-9. Create contentDescription parameter constants for the sight impaired for audio on/off icons

3. Now that your constants are in place, open the /res/layout/
   activity_play.xml file in Eclipse and add two child widget
   tags inside the parent container tag. Configure the first
   with a playAudio ID and sound1.png image source reference and add
   some padding, say 60DIP to compress the icon down in size a bit. Use the
   marginLeft and marginTop parameters with a -50DIP value to pull the icon
   up and to the left a bit.


4. Be sure to add the required layout_width and layout_height parameters,
   set to the value (constant) of wrap_content. Do this using the following XML
   mark-up, as shown in Figure 13-10:

<ImageView android:id="@+id/playAudio" android:src="@drawable/sound1"

android:contentDescription="@string/play_audio" android:padding="60dip"

android:layout_marginLeft="-50dip" android:layout_marginTop="-50dip"

android:layout_width="wrap_content" android:layout_height="wrap_content" />