DisplayKeyboardEvents

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Message

DisplayKeyboardEvents <docname> up|down|both|none

Originator

Client

Response

SyntaxError: insufficient parameters to DisplayKeyboardEvents

SyntaxError: invalid parameters to DisplayKeyboardEvents

SyntaxError: second parameter must be up/down/both/none

Error: document docname not found by DisplayKeyboardEvents

Info: keyboard events set

Response (immediate socket)

Success

Failure

Details

Enables or disables keyboard events for the document.

If the second parameter is 'down', pressing a key generates an event. If the second parameter is 'up', only releasing a key generates an event. If the second parameter is 'both', both the pressing and releasing of a key generate events. If it is 'none', then no key events are generated.

Keyboard events are only useful for situations in which a single subject is being tested using a single display device. Thus, keyboard events are only generated if (1) the client has enabled keyboard events for a document; (2) the document is being displayed in a window; (3) the window has the input focus. The authors only envisage this being useful for human testing.

When a keyboard event is generated, the following message is sent to the client:

KeyEvent: <char> <updown> <docname>

where

char is the Windows virtual-key code of the key in question;

updown is "down" if the key was depressed and "up" if it was released;

docname is the name of the document that generated the event.

•	Keys pressed while the ALT key is held down are ignored.

•

Keyboard repeat events are specifically ignored (i.e. if you depress a key, Windows will generate a stream of events, but Whisker will prevent all but the first message from getting to the client – the next message that can be sent is the release of the same key). It's an operant control system, not a word processor.

•	Certain keys (e.g. ALT) do not generate events. You cannot request events for specific keys (mainly because this would be somewhat tedious; if you feel this is a limitation, contact Rudolf Cardinal at rudolf@pobox.com.)

•	You cannot ask the server whether a specific key is up or down at a given instant.

•	Obviously, keyboard events can be set up for several documents simultaneously, and/or by several clients, but the Windows focus can only be in one window (document) at a time, and events are directed to that document's client.

•	The key codes are shown in the charts on the following pages.

Revision history

Implemented by WhiskerServer version 2.3.