11 Keyboard Operations
The graphics library contains functions that report key presses from the keyboard. The functions get-key-press and ready-key-press return a “key-press descriptor,” and then key-value takes the descriptor and returns a character or symbol (usually a character) representing the key that was pressed. Key presses are buffered and returned in the same order in which they occurred. Thus, the descriptors returned by get-key-press and ready-key-press may be from presses that occurred long before these functions were called.
(get-key-press viewport) → key-press? viewport : viewport?
Returns the next key press in the viewport, waiting for a
key press if necessary.
(ready-key-press viewport) → key-press? viewport : viewport?
Returns the next key press in the viewport or returns
#f if none is available. Unlike get-key-press,
ready-key-press always returns immediately.
Returns a character or special symbol for the key that was
pressed. For example, the Enter key generates #\return, and the
up-arrow key generates 'up. For a complete list of possible
return values, see get-key-code.