Legacy Document

Inside Macintosh: Interapplication Communication /

Chapter 9 - Recording Apple Events / Factoring Your Application for Recording

Sending Apple Events Without Executing Them

If an application is fully factored, it carries out almost all the tasks a user can perform by sending itself Apple events in the manner illustrated by the listings in the preceding sections. However, in some cases it may not be practical to send an Apple event that actually executes a task performed by the user.

For example, if the user drags a window by its title bar from one position to another, it is inefficient to send a series of Apple events that move the window through a series of positions until the user releases the mouse button. Instead, your application can call the Window Manager routine DragWindow to allow the user to drag the window to a new position. Until the user releases the mouse button, it's not possible to send a single Apple event that drags the window to the new position, because the new position is not yet known. When DragWindow returns, the window has already been dragged to its new position, and its window record has been updated.

At this point your application can send itself the Set Data event that performs the same action; but to avoid repeating the action that was just performed with DragWindow, you should add the kAEDontExecute constant to the sendMode parameter of the AESend function when you send the event. The Apple Event Manager then sends the Set Data event to the recording process, if any, but does not send it to the application.

Listing 9-5 shows an application-defined routine, MyDoDragWindow, that illustrates this approach. The MyDoDragWindow routine calls DragWindow in the usual way, then uses another application-defined routine, MyCreateAESetWindowPos, and the AESend function to create and send a Set Data Apple event that sets the window position to the new location. However, because the window has already been moved, there is no need to execute the Set Data event. To send the event for recording purposes without actually executing it, the MyDoDragWindow routine adds the kAEDontExecute constant to the sendMode parameter of the AESend function when it sends the Set Data event.

Listing 9-5 A routine used by a factored application to handle window movement

PROCEDURE MyDoDragWindow (theWindow: WindowPtr; startPt: Point; 
                          boundsRect: Rect);
VAR 
   newPos:        Point;
   index:         Integer;
   theAppleEvent: AppleEvent;
   reply:         AppleEvent;
   myErr:         OSErr;
BEGIN
   DragWindow(theWindow, startPt, boundsRect);
   newPos := WindowPeek(theWindow)^.contRgn^^.rgnBBox.topLeft;
   index := MyIndexFromWndwPtr(theWindow);
   MyCreateAESetWindowPos(index, newPos, theAppleEvent);
   myErr := AESend(theAppleEvent, reply, kAENoReply + 
                     kAECanInteract + kAEDontExecute,
                     kAENormalPriority, kAEDefaultTimeout, NIL, 
                     NIL);
END;

If recording has been turned on and the user moves a window, the Apple Event Manager automatically sends the scripting component a copy of the Set Data event sent by the MyDoDragWindow routine but does not send the event to the application. The scripting component records the event as a statement in a compiled script. When a user executes the recorded script, the scripting component sends the same Set Data event to the application. The application's handler for the Set Data event then changes the position of the window.