unlimited undo's for text fields

Frank Leahy frank at backtalk.com
Mon Feb 28 11:04:27 CST 2005


On Feb 28, 2005, at 5:00 PM, use-revolution-request at lists.runrev.com 
wrote:

> From: "J. Landman Gay" <jacque at hyperactivesw.com>
> Subject: Re: unlimited undo's for text fields
> To: How to use Revolution <use-revolution at lists.runrev.com>
> Message-ID: <42234823.9000200 at hyperactivesw.com>
> Content-Type: text/plain; charset=us-ascii; format=flowed
>
> On 2/28/05 8:44 AM, Paul wrote:
>
>> I think Dar is right in that a message is not sent when a modifier key
>> is pressed on the Mac, but one can check to see if a modifier key is 
>> down.
>
>
> So there is no good way to get a signal when the command key, shift 
> key,
> or option key are depressed alone if you need to trap for that behavior
> on a Mac.
>
> As for how other games do it -- I don't know. Scott Raney told me it
> wasn't possible, because the OS sends no message. So I am not sure how
> other game programs manage it.


They do it by "polling", i.e. they sit in a tight loop watching the 
keymap (an internal Mac data structure that has the status of all the 
keys on the keyboard).

FYI, there was a decision made, a long time ago (circa 1983), that the 
Mac event system would not report shift, option, command or control key 
downs to applications.  The only way to determine if those keys are 
down is via polling, which can be done in Revolution by using an idle 
handler...

on idle
	if the shiftkey is down then
		... do something
	end if
end idle

-- Frank

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