A tiny systray utility to help me keep track of keyboard layers, showing the current layer.
I use a ZMK firmware powered board which can have multiple layers of keybindings, but I don't have a screen or LEDs on the board to keep track of the current layer.
Since I use certain bindings that conflict depending on the use case (i.e. a acts as
both the letter a and as a layer swap key, depending on if its tapped or held), I wanted
a very simple way to check the current layer. That way, when I need a to be held (say if
I'm playing a game), I can make sure the keyboard is in game mode and not typing mode.
Similarly, I have a different layout when I'm on Mac vs Windows.
Starting from some basic, default state...
Lets swap to a gaming mode by pressing the layer change button on my board...
Or perhaps to one setup for mac...
Or toggle the output from USB to bluetooth...
Written in golang, to produce a single, self-contained binary for every platform. That
is, when I press a layer swap key (to move into gaming mode for example), as well as
swapping layer, a unique keycode is sent to the system that kb_ui reacts to, swapping
the current state of the tray, updating the tray icon to a user selected icon.
Layers are defined in a json file with their name, icon and the input key-press
that activates it.
As stated previously, this doesn't use any HID features or anything so smart, it
relies on keycodes being sent to the host. This means my layer change bindings
had to be updated to include these unique keycodes, and also tell kb_ui what they
are.
On the kb_ui side, launch it by double clicking, then right click the system tray
icon, configure. That should open up the default JSON config in your editor (or copy
the path and open it yourself if it defaults to your browser).
Most importantly, there are the icon swap bindings, defined as follows:
{
"key": "1",
"mods": "ctrl-shift-win-alt",
"name": "Default",
"icon": "kb_light",
"dark_icon": "kb_dark"
}Where key defines the input key that will be pressed, mods the sequence of
modifier keys that will be held at the same time. name is the name you want to
give the layer, icon and dark_icon are relative paths to the icon that you
want to use, in ico format (kb_light, kb_dark and disconnected are built
in icons, so just use strings).
The connect toggle binding is set individually, but works the same. The connect toggle binding swaps the icon between the current layer icon, and the disconnect icon (to show output device state).
An example of my config can be found here.
Similarly, my ZMK config, with the macros to actually output these layer change keybinds can be found here. These are just simple macros that send the corresponding keybinding that I've defined in my config when I swap layer / swap output device.
There is the obvious limitation here, that if I swap my board to my Mac, and then swap to a mac based layout... my PC has no idea about the layer change, so when I swap back its out of sync. A pain sure, but one swap and it gets back in sync and it hardly seems worth fixing when ZMK should in the future be able to tell the current layer easily enough. So I'll swap to HID codes then, rather than fixing the odd edge case now.