Navigator — navigator

A screen somebody controls the house from: a Juno OSD on a television, a wall panel, a tablet in a dock. The thing Control4 calls a navigator, and the reason the word is used here rather than "display" — a television is a display and is a different object entirely, one this drives.

It controls; it is not controlled. Nothing in a house asks a navigator to do something, so this contract has almost no commands: what it is for is being placed. A screen in the kitchen should open on the kitchen, and the only way it can know that is for somebody to have said which room it is in — which is exactly what putting a device in a room already means everywhere else in Juno. Nothing new had to be invented for it; a navigator is a device, and devices live in rooms.

The identity is the MAC, in serial. Two Pis flashed from one card image are identical in every other respect — same hostname scheme, same software, same everything — so the burned-in address is the one thing that distinguishes them, and it is what a room assignment has to survive being keyed on. Reflash the card and the assignment still holds; swap the SD into a different Pi and it correctly does not.

There are no commands at all, which is deliberate rather than unfinished — keypad is the same shape for the same reason. A navigator would want an identify ("say which one you are, so I can tell which room I am standing in"), and it is not here because the screen has no control channel yet to receive one. A contract that claimed it would be a contract that lies.

Capabilities

Declared in the driver manifest under [[proxy]] capabilities. Anything not declared takes the default below.

Capability	Type	Default	Meaning
has_cec	bool	false	Has an HDMI-CEC line to a television. It is not driven from here — a screen with this gets a cec_link device of its own — but whether the hardware has one at all is a fact about the screen, and this is where facts about the screen live.
has_control	bool	false	Accepts navigation commands over a channel back to the screen. True for an OSD a remote drives; false for a tablet that is only placed.
has_mixing	bool	false	The navigator has independent voice and media playback paths
has_pause	bool	false	Media on the navigator's companion output can be paused and resumed around voice
has_voice	bool	false	Voice replies and announcements can be delivered to this navigator
is_audio_source	bool	false	Its sound goes with the picture, down the same lead.
is_video_source	bool	false	Its picture goes somewhere — a television, a matrix — rather than being looked at where it is.

Commands

dpad

Only present when has_control is declared true.

Parameter	Type	Notes
key	one of up · down · left · right · select · back · home · menu · info

pause

Only present when has_control is declared true.

No parameters.

play

Only present when has_control is declared true.

No parameters.

play_pause

Only present when has_control is declared true.

One key for both, which is what a remote's transport row actually has.

No parameters.

skip_back

Only present when has_control is declared true.

No parameters.

skip_forward

Only present when has_control is declared true.

No parameters.

stop

Only present when has_control is declared true.

No parameters.

Notifications

online_changed

Parameter	Type	Notes
online	bool

showing_changed

Which room the screen is showing, or nothing when it is on the house view.

Parameter	Type	Notes
room	string

voice_endpoint_changed

Where a voice switch can deliver replies for this navigator. Empty means the voice player is not currently reachable. This is deliberately on the navigator rather than its companion media output: media can be disabled in a distributed-audio room while voice remains available on the screen.

Parameter	Type	Notes
endpoint	string

State

Last-known values core keeps for a binding of this proxy.

Key	Type	Meaning
address	string
endpoint	string
model	string
online	bool
serial	string
showing	string