From: Nat Pryce <nat.pryce@...13media.com>
Date: 2001-08-07T19:36:07+09:00
Subject: [ruby-talk:19278] Re: Ruby/Tk: how to discard excess messages

Ignore any other presses and scroll the window with a timer callback.

E.g. rough pseudocode:

@key_pressed = Hash.new; key_pressed.default = false
@scroll_timers = Hash.new # timers indexed by key

def on_key_press( key )
    if not @key_pressed[key]
        @key_pressed[key] = true
        start_scroll( key )
    end
end

def on_key_release( key )
    @key_pressed[key] = false
    if @scroll_timers.has_key? key
        cancel_timer @scroll_timers[key]
    end
end

def start_scroll( key )
    do_scroll( key )
    @scroll_timers[key] = after( 0.25, proc {continue_scroll( key ) } )
end

def continue_scroll( key )
    if @key_pressed[key]
        do_scroll( key )
        @scroll_timers[key] = after( 0.25, proc { continue_scroll( key ) } )
    else
        @scroll_timers.delete( key )
    end
end

----- Original Message -----
From: "Albert Wagner" <alwagner@tcac.net>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Tuesday, August 07, 2001 2:06 AM
Subject: [ruby-talk:19266] Re: Ruby/Tk: how to discard excess messages


> Thanks, Nat.  That's useful to know.  I didn't realise that no releases
were
> being sent.  However, I still have a problem:  I am using the up/down
arrow
> keys to scroll.  I want to be able to hold the key down; I just don't want
> presses any faster than I can redraw the  window.
>
> On Monday 06 August 2001 16:41, you wrote:
> > From: "Albert L. Wagner" <alwagner@uark.edu>
> >
> > > An auto-repeat key is sending additional messages while method is
> > > still processing first message.  How can I discard the excess
> > > messages?
> >
> > Once you have received a KeyPressed event for a particular key, ignore
> > further KeyPressed events for the same key until you receive a
KeyReleased
> > event for that key.  An auto-repeating key sends multiple KeyPressed
events
> > without any KeyReleased events until the user actually releases the key.
>