Using the _key commands

[PhilOfPerth]

Is the following sample using the _KeyClear,  _Limit, and _keyhit functions correctly? (not worried about the rest at this point). It seems to be ok, but I'm not sure about placement of  _limit, and whether it will be called more times than necessary.
_KeyClear
Print "hit a key"
GetAnAction:
_Limit 30 '                                              limit resource usage
k = _KeyHit '                                            get code of key press
Locate 12, 40: Print k; Space$(5) '                      erase previous key code
If k < 1 Then GoTo GetAnAction '                        if there are no keys pressed, have another look - but only do this max 30 times per second
Locate 13, 1: Print Space$(13); '                        erase previous key code announcement
Locate 13, 1
Print "ok, saw"; k '                                    announce key that was recognized
GoTo GetAnAction '                                      look for another key press

[King Mocker]

Phil

Add this line, Locate 10, 10: Print n:n = n + 1,
Then run it
Then move the _Limit 30 to be before the GetAnAction: label and run it again to see the difference.

_KeyClear
Print "hit a key"

GetAnAction:
_Limit 30 '                                              limit resource usage
k = _KeyHit '                                            get code of key press
Locate 12, 40: Print k; Space$(15) '                      erase previous key code
'###
Locate 10, 10: Print n:n = n + 1
'####
If k < 1 Then GoTo GetAnAction '                        if there are no keys pressed, have another look - but only do this max 30 times per second
Locate 13, 1: Print Space$(20); '                        erase previous key code announcement
Locate 13, 1
Print "ok, saw"; k '                                    announce key that was recognized
GoTo GetAnAction '                                      look for another key press

[SMcNeill]

Limit placement looks fine to me -- it's in your innermost loop, and the one where the user is going to interact with the most.  

From what I see, after I restructured the code to get rid of the GOTOs, you might want to move the _KEYCLEAR however.

Code: (Select All)

Print "hit a key"
Do
    _KeyClear '                              clear the buffer before looking for any new keystrokes
    Do
        _Limit 30 '                          limit resource usage
        k = _KeyHit '                        get code of key press
        Locate 12, 40: Print k; Space$(5) '  erase previous key code
    Loop Until k > 0 '                      if there are no keys pressed, have another look - but only do this max 30 times per second
    Locate 13, 1: Print Space$(13); '        erase previous key code announcement
    Locate 13, 1: Print "ok, saw"; k '      announce key that was recognized
Loop Until k = 27 '                          look for another key press (exit with ESC)

For this short of an example, I'd think the above is what you want.  Just ask yourself, "Do I want to process current key hits, or hits off the keyboard buffer?"  Here, it appears you're just wanting to print the code for current key hits -- thus the _KEYCLEAR before the _KEYHIT loop.  If you're wanting to check the whole buffer and process it however, you'd probably want that _KEYCLEAR outside the main loop completely, and between the PRINT and the DO statement in the code above. 

[PhilOfPerth]

Limit placement looks fine to me -- it's in your innermost loop, and the one where the user is going to interact with the most.  

From what I see, after I restructured the code to get rid of the GOTOs, you might want to move the _KEYCLEAR however.

Code: (Select All)

Print "hit a key"
Do
    _KeyClear '                              clear the buffer before looking for any new keystrokes
    Do
        _Limit 30 '                          limit resource usage
        k = _KeyHit '                        get code of key press
        Locate 12, 40: Print k; Space$(5) '  erase previous key code
    Loop Until k > 0 '                      if there are no keys pressed, have another look - but only do this max 30 times per second
    Locate 13, 1: Print Space$(13); '        erase previous key code announcement
    Locate 13, 1: Print "ok, saw"; k '      announce key that was recognized
Loop Until k = 27 '                          look for another key press (exit with ESC)

For this short of an example, I'd think the above is what you want.  Just ask yourself, "Do I want to process current key hits, or hits off the keyboard buffer?"  Here, it appears you're just wanting to print the code for current key hits -- thus the _KEYCLEAR before the _KEYHIT loop.  If you're wanting to check the whole buffer and process it however, you'd probably want that _KEYCLEAR outside the main loop completely, and between the PRINT and the DO statement in the code above. 

Thanks Steve. I think I get it, I'll go play some more.