Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mcnc!thorin!oscar!tell
From: tell@oscar.cs.unc.edu (Stephen Tell)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Double Click
Summary: There is a system function to do this.
Message-ID: <12487@thorin.cs.unc.edu>
Date: 8 Mar 90 18:57:15 GMT
References: <79yO02zd8fMp01@amdahl.uts.amdahl.com>
Sender: news@thorin.cs.unc.edu
Reply-To: tell@oscar.cs.unc.edu (Stephen Tell)
Organization: University Of North Carolina, Chapel Hill
Lines: 27


Re: how to tell if two mouse events constitute one double click or two
single clicks?

There is a function in one of the libraries to to this.  I think it is
called DoubleClick(), but I'm not sure.  It was in the 1.1 (Addison Wesley)
RKMs.  The arguments are
DoubleClick(s1, m1, s2, m2)
where s1 and m1 are seconds and milliseconds (microseconds?) of the first
click and s2 and m2 are the second click.  I may have seconds and fractions
of a second reversed.  I think all 4 args are longs.  It returns true (nonzero)
if the two clicks are a double-click, and otherwise returns false (zero).

The routine apparently subtracts the time and compares
it with that set by the user in Preferences.
The time values come from the Intuition message itself, thats why they
all have a timestamp (well, one reason anyway.)

Its been a long time since I wrote user-interface code in C, but I'm pretty
sure the essentials are right.  The big win to using the DoubleClick routine
is that the user's preference of double-click duration is automaticly used.
Thats why we have Preferences in the first place - no "best typical values"
allowed; let the user decide.
--------------------------------------------------------------------
Steve Tell					tell@wsmail.cs.unc.edu
CS Grad Student, UNC Chapel Hill.
Former chief engineer, Duke Union Community Television, Durham, NC.