Feature: "Shifted Keycodes", e.g. assigning `!` to a key press or mod-tap behavior.

[petejohanson]

Potential fix/idea:

• Use upper bits of the first parameter to key_press, etc to have the enum flag of the mods included. UGH, but not sure how to avoid this if we want this to also work w/ things like mod-tap, where the other parameter is already used.
• Add defines to keys.h that are + , e.g. something like #define BANG (NUM_1 + HELD_MODS(MOD_LSFT))
• Updated "key code state changed" event to include mods expected with that keycode.
• Handling in the endpoint logic to inspect the mods and handle accordingly. Need to be careful w/ handling mod state, so we don't release mods early, etc.

[BrainWart]

For people who can't wait for a better solution, brainwart/zmk@e09246a8e664c2e873a21cd8d4903f445156c51d

This does not add new keycodes. It just applies two keys one after another. Usage: &mkp LSFT NUM_7

[okke-formsma]

I have an implementation proposal for this in https://github.com/okke-formsma/zmk/tree/modifiers / https://github.com/zmkfirmware/zmk/pull/153

It brings the following changes:

• Modifiers are counted. If you press LSFT twice, only when it's released for the second time the bitflag in the HID is zeroed.
• No more differentiation between MOD_LSFT and LSFT. It's always LSFT. You can use &lsft A or &kp (A | LSFT) for the same result. A shift key would be &kp LSFT (preferred) or &lsft 0 (bad form but it works)
• This makes mod-taps with multiple mods possible: &mt (LSFT | LCTL) A

The mods are implemented as flags in the third byte of the keycode. This overloads the keycodes a bit, but I feel that's warranted in this case.

There has been some discussion about this on discord: https://discordapp.com/channels/719497620560543766/719544230497878116/751160749203652649

[okke-formsma]

We had a chat on discord about not adding shifted keycodes to the default codes, as they are locale-dependent. (e.g. shifted keycodes result in a different character being typed depending on Dutch/Belgian/French/German/..., UK or US setting.)

By forcing users to use &lsft NUM_3 or &kp (NUM_3 | LSFT), we make them aware of what is happening.

[innovaker]

Would this syntax (using MACROs) be more robust in terms of future implementation refactoring? LCTRL(LSFT(A))

It looks uglier, but it could be eased with composite convenience MACROs such as: LS() LCS() LSC() LCSA() etc.

This would hide some of the implementation detail (bit masks) on primarily user-facing code, potentially easing localized refactors?

[tominabox1]

I like the idea of concatenating mods like this fwiw

I would love to not use pipe's in my code because I don't know where I put them on my keyboards haha

[innovaker]

This syntax would probably also transfer better into whatever supersedes DT/DDM for keymaps/bindings/behaviours, in the future.

[okke-formsma]

discussed on discord https://discordapp.com/channels/719497620560543766/719544230497878116/770359370814586950

• Top byte will be mod flags.
• Simple macros to add each mod flag to a keycode. One per flag.
• Regular normal keycodes for modifiers will be used for those keys that are "just a shift key"
• Same kp used consistently, no duplicated behavior aliases.

#define LS(keycode) (MOD_LSFT << 24) & keycode)

[okke-formsma]

The modifiers branch now includes "implicit" and "explicit" modifiers. An modifier is "explicit" when it's called like &kp LEFT_CONTROL. A modifier is "implicit" when it's added to another key; &kp LC(A).

Explicit modifiers are held until their key is released.

Implicit modifiers are held until their key is released or another key is pressed. This makes rolling over modified keys possible; pressing LS(A) and then B, and then releasing LS(A) and B should output "Ab" (and not AB).

There is one known issue in the current implementation. Implicit modifiers are also released when other keys are released. namely that implicit modthat's not supported: A down, LS(B) down, A up, (wait) LS(B) up. The expected output would be aBBBBBBBBBBBBBB but the actual output is aBbbbbbbbbbb because the shift modifier is released when the A key is released.