[elektrinis]

I understand this is a non-Kodi question, but a general problem.
I want to use a windows tablet as a media device with a projector permanently connected to HDMI port. When projector is off, I want Kodi to be displayed on the tablet, showing music cover art, etc. However when I switch the projector on, I would like Kodi to move to the projector, leaving tablet's integrated display blank/off. I hope this is clear enough.

Now, very likely I need some 3-rd party software, but was just wondering if anyone tried this before.
So far I am unable to make windows detect whether HDMI projector is on or off. The projector model is BenQ W1080 and is supports CEC, but not sure if that matters..This is where I got stuck for now.

[PatK]

I don't have a projector, I do have a flat TV in which I use Kodi and with that said, I'll pass along a few tips that may or may not be useful.

1) In windows, using the DisplaySwitch.exe in windows (win+p) I can swtich with a keyboard.
2) Using a small script using DisplaySwitch.exe linked to a desktop icon, it's possible to launch Kodi to secondary display, on exit return to primary display
3) Using my Onkyo reciever as an AVR, it auto switches the display on launch (remembering the last set-up) without CEC
4) Using CEC on all devices, there should be some provision for moving the display whenyuturn on various devices.
5) I suppose there is some fancy remote perhaps using a flirc that could handle all of this.

I use #1,2 and 3 depending, don't use #4 CEC, seems to get confused.

[elektrinis]

I don't have a projector, I do have a flat TV in which I use Kodi and with that said, I'll pass along a few tips that may or may not be useful.

1) In windows, using the DisplaySwitch.exe in windows (win+p) I can swtich with a keyboard.
2) Using a small script using DisplaySwitch.exe linked to a desktop icon, it's possible to launch Kodi to secondary display, on exit return to primary display
3) Using my Onkyo reciever as an AVR, it auto switches the display on launch (remembering the last set-up) without CEC
4) Using CEC on all devices, there should be some provision for moving the display whenyuturn on various devices.
5) I suppose there is some fancy remote perhaps using a flirc that could handle all of this.

I use #1,2 and 3 depending, don't use #4 CEC, seems to get confused.

Hi PatK and thanks for your input. The problem is that I am bit lazy to manage switching myself, and a much bigger issue is that the system is being used by much less technical people than myself, and it is very, very hard to explain and educate what does what, like to the level that projector only displays video, that you should not point to a monitor and call it a computer, and that a firefox is not "the internet". You get the idea what I am dealing with here - it must just work.
It should be clear by now why I don't want to use a mouse or keyboard, it must be a single remote solution. Also in this system I don't want to ever exit KODI. It must be running 24/7, but jumping between displays. I also don't have a "AV receiver", it's just an active speaker system.
That said, maybe it is possible to solve from OS side? For example if HDMI device is detected to be ON, the OS could enter projector mode by disabling built-in display and moving everything to secondary external screen. But again, I am still unable to find a way to detect a power state of HDMI device. It only detects when cable is plugged or unplugged, but has absolutely no idea if device is powered on or not. The projector has CEC enabled, but it looks like the tablet itself does not support it. I did get the same results with laptop as well. Frankly, I'm not sure if CEC is what I need here.