#10 Create configuration screen for sound and brightness (if available)

As far as I can tell, the screens don't have a brightness setting.

With the 'quick dim' feature, the brightness shouldn't be such a high priority.

The sound is a priority and should have a facility to reduce be able to set the volume in the driver facing application.

This "works for me" (save into changevol script):

#!/bin/bash

volpct=100
if [[ "$1" != "" ]] ; then
  volpct=$1
fi
numid=`amixer controls | grep 'PCM Playback Volume' | head -n1 | cut -f1 -d',' | cut -f2 -d'='`
if [[ "$numid" == "" ]] ; then exit 1; fi
amixer cset numid=$numid "${volpct}%"  > /dev/null
exit 0

Quick test:

changevol 90
espeak "I'm speaking at 90% volume" --stdout | aplay -
changevol 100
espeak "I'm speaking at 100% volume" --stdout | aplay -

Note that at 50% it's barely audible (for me).

Brightness functionality is being deferred to a later ticket.

The configuration screen with a volume slider is implemented.

Still TODO is to hook up the diu_ui.js slider callback to make an API request and have the DIU server make the appropriate volume change.