Implement an emit command (#4937)

[Tert0]

Closes #4937

Command Syntax: emit <press|release|press-release> <criteria> <keys>

Parameters

• action: specifies whether to press, release the keys or do both
• criteria: first window that matches the criteria will get the key input
• keys: modifiers and keys separated by +

Examples

• emit press-release [app_id=com.obsproject.Studio] ALT+F8
• bindsym --no-repeat Ctrl+T emit press [app_id=wev] Ctrl+A
• bindsym --no-repeat --release Ctrl+T emit release [app_id=wev] Ctrl+A

Test

1. Open wev -f wl_keyboard with a terminal
2. Move the wev window into another workspace
3. Run

swaymsg 'bindsym --no-repeat Ctrl+T emit press [app_id=wev] Ctrl+A'
swaymsg 'bindsym --no-repeat --release Ctrl+T emit release [app_id=wev] Ctrl+A'

4. Press and hold Ctrl+T
   -> The terminal running wev should show that Ctrl+A was pressed
5. Release Ctrl+T
   -> The terminal running wev should show that Ctrl+A was released

Code Structure

I am not sure if I should move the code (for converting xkb keysym to key codes), that I copied from the sway/commands/bind.c, to common/utils.c or maybe somewhere else.

[emersion]

Now that we have Wayland protocols for this feature, I'm not sure adding IPC commands is really desirable…

[Tert0]

Which wayland protocols are you referring to?

[emersion]

virtual-keyboard and virtual-pointer.

[Tert0]

As far as I understand the virtual-keyboard protocol, it does not allow sending keys to unfocused windows. This would be a useful feature to "emulate" global hotkeys for applications.
In #4937 are workarounds to do something like this with wtype but these solutions rely on switching to the window with swaymsg and to avoid infinite recursion you can not send the same keys that you bind the script to.

[kennylevinsen]

As far as I understand the virtual-keyboard protocol, it does not allow sending keys to unfocused windows.

A Wayland surface must by definition have keyboard focus to receive key events. This is what enter/leave is.

The proposed command gives keyboard focus to the window matching the criteria (which is the bit "missing" from virtual-keyboard) and then issues a single synthetic key event. Unless all key events are sent at once, this would race with the keyboard state of the window the user currently focused and any keyboard inputs they are typing.

[Tert0]

A Wayland surface must by definition have keyboard focus to receive key events. This is what enter/leave is.

Using swaymg it additionally gives them visual focus (wl_surface::enter + shows them).

Unless all key events are sent at once, this would race with the keyboard state of the window the user currently focused and any keyboard inputs they are typing.

Is there a way with wlroots to send all key events at once?