KEY(n)

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Revision as of 14:52, 20 April 2022 by SMcNeill (talk | contribs) (Created page with "'''KEY(n)''' assigns, enables, disables or suspends event trapping of a keypress by setting the flag ON, STOP or OFF. {{PageSyntax}} : KEY({{Parameter|number}}) {ON | OFF | STOP} {{PageDescription}} * Predefined and user defined KEY event number assignments to use with KEY(n): {{WhiteStart}} '''1 to 10'''.............Reserved '''F1 to F10''' function keys only. '''11, 12, 13 and 14'''...Reserved '''Up, Left, Right and Down''' numeric...")
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KEY(n) assigns, enables, disables or suspends event trapping of a keypress by setting the flag ON, STOP or OFF.


Syntax

KEY(number) {ON | OFF | STOP}


Description

  • Predefined and user defined KEY event number assignments to use with KEY(n):

Template:WhiteStart 1 to 10.............Reserved F1 to F10 function keys only.

    11, 12, 13 and 14...Reserved Up, Left, Right and Down numeric keypad arrows only
    15 to 29............user-defined keys using value: CHR$(keyflag)  + CHR$(scancode)
    30 and 31...........Reserved F11 and F12 function keys only.

Template:WhiteEnd

  • Keypresses can be read during INKEY$, INPUT$ or INPUT procedures without losing the input.
  • Key event reads will also interrupt SLEEP.
  • KEY(n) specific status modes are:
    • ON enables specific keypress events to be monitored.
    • STOP suspends specific keypress reads, but remembers them. When re-enabled the key presses will be returned.
    • OFF disables specified keypress reads and will not remember the event.


Examples

Example 1: How to trap the LEFT direction keys on both the dedicated cursor keypad and the numeric keypad.

  
KEY 15, CHR$(128) + CHR$(75) ' Assign trap for LEFT arrow key on the cursor keypad
ON KEY(15) GOSUB CursorPad     
KEY(15) ON ' enable event trapping                   

ON KEY(12) GOSUB NumericPad ' Trap LEFT key on number pad
KEY(12) ON ' enable event trapping                      

DO
LOOP UNTIL UCASE$(INKEY$) = "Q" ' Idle loop for demo
SYSTEM

CursorPad:
PRINT "Pressed LEFT key on cursor keypad."
RETURN

NumericPad:
PRINT "Pressed LEFT key on numeric keypad."
RETURN  


Example 2: Trapping the F5 keypress.

  
KEY(5) ON
ON KEY(5) GOSUB execute
PRINT "Press F5 (or ESC) to quit!)"
DO
LOOP UNTIL INKEY$ = CHR$(27) ' idle loop
SYSTEM
execute:
PRINT "You pressed the F5 key..."
SLEEP 1
PRINT "Press any key to continue..."
SLEEP  


See also



Navigation:
Main Page with Articles and Tutorials
Keyword Reference - Alphabetical
Keyword Reference - By usage
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