Key Handling

While Keyman Core does not generally emit actions from key up events, the emit_keystroke value for a key up event will match the corresponding key down event, in order to avoid 'stuck key' scenarios'.

Usually the processor won't handle any frame keys and let the application deal with it. This allows shortcut keys like Ctrl+C to work. One exception is the Backspace key which is handled internally if enough context is available. Keyboards can define rules for other frame keys, e.g. Ctrl+Key which are then also handled internally. Regular keys will be handled by the processor.

Note that there is a difference between CLDR/LDML and KMN keyboards if there are no rules/transforms defined for a key: KMN keyboards will output the cap value of the key (e.g. pressing a will output a if no rule is defined), whereas CLDR/LDML keyboards will suppress any output for that key. However, km_core_actions.emit_keystroke will be FALSE for both KMN and CLR/LDML keyboards.

The following table lists the state of km_core_actions.emit_keystroke on return of km_core_process_event when the following type of key is pressed:

Type	KeyDown/Up
Core key with rule	FALSE
Core key w/o rule	FALSE
Framekeys:
Enter	TRUE
Backspace¹	FALSE
Backspace²	TRUE
Ctrl+Key	TRUE
Modifier key Shift	TRUE
Modifier key Ctrl	TRUE
Modifier key LAlt	TRUE

1: context available
2: without or with empty context