Tips & Tidbits

By Neil Ticktin, Editor-in-Chief

Tip of the month

A frequently asked question is “How to make a menu bar within a window, but makeit SIMPLE?” I have found the answer deep in the UPMG folder on the 7.0 Beta-Bang CD-Rom. This folder is a “must read” for finding clever and simple answers to many questions of this kind. I have written the code below for better readability, but the credit for the trick must be given to the UPMG file. Before calling PopUpMenuSelect, install a MenuHook. In the hook, if the mouse is out of the menu rect (and out of the menu title rect), post a mouseUp event to exitPopUpMenuSelect.

Doing it this way, the user can browse between pop-up menus without releasing themouse button, exactly like in the real menu bar. Warning: abuse of this trick will quickly drive your program to a very disconcerting user-interface. Are you really sure you need a menu bar in thiswindow?

Benoît Widemann

/* 1 */

// Global variables

short gCurrentMenu;// current menu index
MenuHandle gMenu[NUMBER_OF_MENUS];
Rect gMenuTitleRect[NUMBER_OF_MENUS];  // menus title rects in window

// There was a click in window's menubar
// Returns the item selected or 0 if no selection
// If the returned item is non-zero, the menu index is gCurrentMenu

short windowMenuSelect(WindowPtr theWindow)
{
   ProcPtr saveMenuHook;
   Point p;
   short selectedItem;

   SetWRefCon(theWindow, SetCurrentA5());  // save our A5 in window refcon
   saveMenuHook = MenuHook;// save current value in MenuHook
   MenuHook = (ProcPtr)myMenuHook; // install our menu hook
   SetPort(theWindow);
   while (Button()){   // don't use StillDown here!!
   GetMouse(&p);
   for (gCurrentMenu=0; gCurrentMenu<NUMBER_OF_MENUS; gCurrentMenu++) 
 {
   // find in which menu title rect is the mouse
   if (PtInRect(p, &gMenuTitleRect[gCurrentMenu])) {
   InvertRect(&gMenuTitleRect[gCurrentMenu]);
   p.h = gMenuTitleRect[gCurrentMenu].left+1;
   p.v = gMenuTitleRect[gCurrentMenu].bottom+1;
   LocalToGlobal(&p);
   // use only the item part returned
   selectedItem = (short)(PopUpMenuSelect(gMenu[gCurrentMenu], p.v, p.h, 
0) &
0x0000FFFF);
   InvertRect(&gMenuTitleRect[gCurrentMenu]);
   break;
   }
   }
   }
   MenuHook = saveMenuHook;// restore Menu Hook
   return(selectedItem);
}

// the menu hook

pascal void myMenuHook()
{
   Point p;
   long sysA5;

   sysA5 = SetA5(GetWRefCon(FrontWindow())); // restore our A5
   GetMouse(&p);
   if (p.v < 20 && !PtInRect(p, &gMenuTitleRect[gCurrentMenu])) {
   (void)PostEvent(mouseUp, nil);  // exit PopUpMenuSelect
   }
   (void)SetA5(sysA5); // restore system A5
}

NEED FOR SPEED

To execute system routines efficiently, you can by-pass the trap dispatcher byjumping to the routine yourself. Most practicle in tight loops. Take for example the BLockMove routine. Rewrite it as MyBlockMove:

/* 2 */

CONST
  kBlockMoveNum = $A02E; 
{Get the BlockMove Trap word from Inside Macintosh Volume III, Appendix 
C}
VAR
  blockMoveAddress:LongInt;
BEGIN
  blockMoveAddress := GetTrapAddress(kBlockMoveNum);
  start loop...
    MyBlockMove(source,dest,size, blockMoveAddress);
  end loop...
END

Write MyBlockMove in assembler like this:

;3

PROCEDURE MyBlockMove
MOVE.L     A2,D2      /*Save off A2. We'll need it later
MOVE.L     (A7)+,D1   /*Move Return address into D1
MOVEA.L    (A7),A2    /*Put BlockMove address into A2
MOVE.L     (A7)+,D0   /*Place size into D0
MOVEA.L    (A7)+,A1   /*Place destination Ptr into A1
MOVEA.L    (A7)+,A0   /*Place source Ptr into A0
MOVE.L     D1,(A7)    /*BlockMove trashes D1 & D2.
                      /*Save D1(Return address) on stack
MOVE.L     D2,-(A7)   /*Save D2(value of A2) on stack
JSR        (A2)       /*Jump to BlockMove
MOVEA.L    (A7)+,A2   /*Restore A2
MOVEA.L    (A7)+,A1   /*Place Return address into A1
JMP        (A1)       /*Jump to Return Address

MyBlockMove must be in a resident segment!!! For any questions, send an applelink to ISS.

Mark Hajek