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This documents the state of `km_core_actions.emit_keystroke` for different keys pressed. Also some cleanup in other docs. This documents the state after merging #15609 (for ldml keyboards) and NN (for kmn keyboards). Follows: #15609 Build-bot: skip Test-bot: skip
42 lines
2.1 KiB
Markdown
42 lines
2.1 KiB
Markdown
# Key Handling
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For each key press the processor will called twice, for the key down event
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as well as for the key up event. Depending on the type of key pressed the
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processor might handle the key itself or pass it on to the application.
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The value of `emit_keystroke` in `km_core_actions` struct tells if the
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processor handled the key (`emit_keystroke=0`) or not (`emit_keystroke=1`).
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It is important that the same value gets set for both key down and key up
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events, otherwise the application might miss some events which then looks
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to the user like keys are stuck.
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Usually the processor won't handle any frame keys and let the application
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deal with it. This allows shortcut keys like <kbd>Ctrl</kbd>+<kbd>C</kbd>
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to work. The only exception is the <kbd>Backspace</kbd> key which is
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handled internally if enough context is available. Regular keys will be
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handled by the processor.
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Note that there is a difference between CLDR/LDML and KMN keyboards if
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there are no rules/transforms defined for a key: KMN keyboards will
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output the cap value of the key (e.g. pressing <kbd>a</kbd> will output
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`a` if no rule is defined), whereas CLDR/LDML keyboards will suppress
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any output for that key.
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The following table lists the state of `km_core_actions.emit_keystroke`
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on return of `km_core_process_event` when the following type of key is
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pressed:
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|Type | KeyDown | KeyUp |
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|-----------------------------|---------------|----------|
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|Key with rule | FALSE | FALSE |
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|Key w/o rule | FALSE | FALSE |
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|Framekeys: | | |
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|<kbd>Enter</kbd> | TRUE | TRUE |
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|<kbd>Backspace</kbd>¹ | FALSE | FALSE |
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|<kbd>Backspace</kbd>² | TRUE | TRUE |
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|<kbd>Ctrl</kbd>+Key | TRUE | TRUE |
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|Modifier key <kbd>Shift</kbd>| TRUE | TRUE |
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|Modifier key <kbd>Ctrl</kbd> | TRUE | TRUE |
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|Modifier key <kbd>LAlt</kbd> | TRUE | TRUE |
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1: context available<br/>
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2: without or with empty context
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