Related Info: Menu Manager

Tips & Tidbits

By Neil Ticktin, Editor-in-Chief

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

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:

/* 2*/

return
 theMode != 0;

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

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! Especially 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,

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.]

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