Re: [MACTCL] scrollbar 'update idletasks' vs 'Tcl_ServiceAll()'

[Jim I. <ji...@ap...>]

I added this to the bug:

I don't think this is relevant to this bug.  I don't see it on the  
current TOT on 10.3 with the example cited.

Note, the code is not calling "update" just "update idletasks".  You  
can't call Tcl_ServiceAll because the Aqua code is using the Native  
Control to move the mouse around, and if you steal mouse events off  
the queue out from under the control, it doesn't move properly.

But you can replace the call to "update idletasks" with a call to  
TclServiceIdle().  That seems to work just fine in my quick tests.   
The only difference between "update idletasks" and calling  
TclServiceIdle directly is that "update idletasks" calls XSync.  This  
is redundant, because fetching the next event also flushes the  
drawing, and syncing with the server is a cross-process call on Mac  
OS X so it is more expensive than it was in the Classic MacOS.

I think I will switch TOT to calling TclServiceIdle, since it seems  
to make the scrolling a little faster.  But I don't think it has any  
relevance to this bug.

To switch to just calling TclServiceIdle, try the following patch, I  
think this is marginally faster:


Index: tkMacOSXScrlbr.c
===================================================================
RCS file: /cvsroot/tktoolkit/tk/macosx/tkMacOSXScrlbr.c,v
retrieving revision 1.9
diff -p -p -r1.9 tkMacOSXScrlbr.c
*** tkMacOSXScrlbr.c    16 Feb 2004 00:19:42 -0000      1.9
--- tkMacOSXScrlbr.c    14 Mar 2005 18:19:21 -0000
***************
*** 16,21 ****
--- 16,22 ----

   #include "tkScrollbar.h"
   #include "tkMacOSXInt.h"
+ #include "tclInt.h"

   #include <Carbon/Carbon.h>

*************** ThumbActionProc()
*** 673,678 ****
--- 674,691 ----
               interp = scrollPtr->interp;
               Tcl_Preserve((ClientData) interp);
               Tcl_GlobalEval(interp, cmdString.string);
+             {
+                 TkDisplay *dispPtr;
+                 TclServiceIdle();
+                 #if 0
+               for (dispPtr = TkGetDisplayList(); dispPtr != NULL;
+               dispPtr = dispPtr->nextPtr) {
+                   XSync(dispPtr->display, False);
+               }
+                 #endif
+
+             }
+ #if 0
               Tcl_Release((ClientData) interp);
               Tcl_DStringSetLength(&cmdString, 0);
               Tcl_DStringAppend(&cmdString, "update idletasks",
*************** ThumbActionProc()
*** 680,685 ****
--- 693,699 ----
               Tcl_Preserve((ClientData) interp);
               Tcl_GlobalEval(interp, cmdString.string);
               Tcl_Release((ClientData) interp);
+ #endif
           }
       } while ((err == noErr) && trackingResult !=  
kMouseTrackingMouseReleased);



By either 10.2 or maybe 10.3 there were API's to completely draw the  
track and the thumb, etc. for the Aqua scrollbar independently of the  
scrollbar callbacks.  So it would also be possible to remove the  
TrackMouseLocationWithOptions stuff altogether, and just let Tk  
handle the events the way it does for the Unix code, and then draw  
the controls directly.  This is probably the best way to go, making  
the Mac code more like the Unix version.

Jim

On Mar 14, 2005, at 4:55 AM, Vince Darley wrote:

> A recent Tk bug report (crash):
>
> https://sourceforge.net/tracker/? 
> func=detail&atid=112997&aid=1143776&group_id=12997
>
> seems to be triggered on TkAqua because of a direct call to 'update
> idletasks' in the scrollbar code.  Comparing this with the other
> platforms, I see that they use a Tcl_ServiceAll() call, and don't  
> have any
> need to call 'update'.  This approach seems more robust given the  
> unknown
> side-effects of the update command.
>
> Is there any reason TkAqua can't be changed to use an approach that is
> closer to the other platforms?
>
> cheers,
>
> -- Vince
>
>
>
>
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