#1 'Quick dim' button and functionality for DIU display

sleep 0.5 ; xset dpms force off

Feature --- Provide a button that will dim the DIU display. Any other tap to the display should bring the display back to the previous brightness. Background --- When travelling at night, the display is often too bright during normal operation. The glare from the screen could be too bright and so drivers like to dim the display, sometimes completely. While it's tempting to try to do this automatically, this gets tricky as velocity discovery and knowledge of driver intent needs to be done. For example, is this a scheduled stop or is the bus stopping at at a light or stop sign? For the time being, it's probably better to have the driver be in control of when the screen dims or not. Note that this is separate from overall brightness control. Implementation Notes --- There should be a button on the main DIU screen (`ui_screen`) that allows for a 'quick dim' feature. This can be implemented by: ``` sleep 0.5 ; xset dpms force off ``` (see [SO](https://superuser.com/questions/374637/how-to-turn-off-screen-with-shortcut-in-linux)). The `sleep` is to make sure not stray keyboard presses pollute the operation. I believe this will set the screensaver so any other button press should wake up with display. | | | |---|---| | priority | high | | estimate | 1 work unit |