Jul 93 Tips, Tidbits
Volume Number: 9
Issue Number: 7
Column Tag: Tips & Tidbits
Related Info: Menu Manager
Tips & Tidbits 
By Neil Ticktin, Editor-in-Chief
This column is your opportunity to spread the word about little bits of
information that you find out about. These tidbits can be programming related or they
can be user tips that are particularly useful to programmers.
MacTech Magazine will pay $25 for every tip used, and $50 for the Tip of the
Month. Or you can take your award in orders or subscriptions.
To submit a tip, send in a letter to the magazine. E-mail is our preferred
method, but feel free to send something via the US Mail. See page two for all addresses.
If you do send snail mail, enclose a printed copy and a disk copy of the letter so that it
does not have to be retyped.
Tip of the Month
Ever wonder how to have menus without having to give up space to the menubar?
Here's how:
{1}
var
theMenuRect: Rect;
theMenuRgn: RgnHandle;
begin
SetRect(theMenuRect,0,0,screenBits.bounds.right,GetMBarHeight);
theMenuRgn:= NewRgn;
RectRgn (theMenuRgn,theMenuRect);
UnionRgn(GetGrayRgn,theMenuRgn,GetGrayRgn);
...
... {You can now draw over the menubar if you have a valid port
there}
... {If the user clicks in the invisible menubar, it will still pop
up}
...
XorRgn(GetGrayRgn,theMenuRgn,GetGrayRgn);
DisposeRgn(theMenuRgn);
end.
This can be great for games where you could really use the extra space
sometimes. You just have to make sure you don't call DrawMenuBar. What happens is
the menubar is re-drawn. Therefore, make sure you set up the menus before you do
the above or, if you have to call DrawMenuBar, make sure you draw over the entire
menubar during the update event.
Make sure you call XorRgn at the end as this step restores the GrayRgn to what it
was before. It is extremely discourteous not to do so. It would also be a good idea to do
this when your application goes into the backgound, however, when it comes to games,
it's not likely you'll be redrawing menubars and switching back and forth between apps
too much.
- Narayan Sainaney
SNR Enterprises., sainaney@unixg.ubc.ca
Booleans are Booleans are Booleans
This tip was inspired by the Tip of the Month in the April issue. If you recall, the
code contained the statement
if (theMode != 0)
return (true);
else
return (false);
This can be written much more simply (borrowing from another tip in the April
issue) as:
This equivalence of booleans applies in other contexts as well. For example, I
have seen people write something like
If Count = 0 then
NoMore := true
else
NoMore := false
when they can of course write:
/* 3 */
NoMore := Count = 0
Remember: Booleans are values too!
- Lawrence D’Oliveiro, University of Waikato, Hamilton, New Zealand
See also Apr 93 Tips, Tidbits
C and Pascal Strings
The Mac toolbox calls EqualString and UprString perform some useful
string-functions (see Inside Macintosh Volume II, p. 377). However they accept only
pascal-style strings. A possible coding would be:
{ char *s = "this is a π" ;
CtoPstr (s) ;
UprString (s, false) ;
PtoCstr (s) ;
}
Causing the overhead of converting a C-string to Pascal and back. However, the
assembly trap macro only needs a pointer to the string and the length:
/* 4 */
{ shortsLen ;
char *s = "this is a π" ;
sLen = strlen (s) ;
asm {
move.l s, A0
move.w sLen, D0
_UprString
}
}
It’s so much faster! E specially if you already have the length of the string,
instead of having to do the strlen.
- Jan Bruyndonckx
Speedier Conditioning
There is a small speed advantage to writing nested IF-THEN conditions over one
IF-THEN condition that contains the AND or the & operators. The condition:
IF x=5 THEN
IF X=6 THEN
executes faster and generates more compact code than the condition:
IF (x=5) and (y=6) then
and much faster than the condition:
IF (x=5) & (y=6)
The above conditions are semantically identical!
- Marek Hajek,
Hajek’s Solutions, Reno, Nevada
Duo Space Bar problems?
Having problems with your space bar on your Duo? Ray Jackson from Personal
Support Computers in West Los Angeles tells me that many times it is simply a case of
the screw (on the bottom of the Duo) being too tight. It seems that Apple didn't think
through their mounting concepts well enough and sometimes the space bar suffers.
[Ray, my Duo works much better now. Thanks. - Ed.]
- Neil Ticktin, Editor-in-Chief
Timing MPW Commands
Have you ever wanted to know how long an MPW command needs to execute?
Some tools and scripts provide timing functions, but many don't.
For a generic "Time" command, put this script in your :MPW: Scripts: folder:
/* 5 */
Set _started_ `date -n`
{Parameters}
Set _finished_ `date -n`
Echo -n "∂n∂# Execution time in seconds:
Evaluate {_finished_}-{_started_}
Unset _started_, _finished_
Then, enter this in the MPW Worksheet:
Time commandName
where commandName is the name of the script or tool you want to time.
Caveats:
1) The resolution of the "Time" script is one second, and the overhead of the script
itself may be up to one second on slower machines. In other words, don't bother
timing commands if they take only a few seconds to execute, or if you need very
precise timings.
2) This won't work for stand-alone applications. If you're using MultiFinder or
System 7, the script won't wait for the application to finish its run. In Finder 6
or earlier, MPW has to shut down completely when it launches an application,
and the script cannot resume when MPW reloads.
- Lee David Rimar, Oak Park, Michigan