Re: [XForms] New prerelease xforms-1.0.94pre13

[Paul]

After some investigation...

The problem is that a canvas object loses its window
ID after the sequence

  fl_freeze_form();
  fl_set_object_geometry( ...);
  fl_unfreeze_form( form);

Here is a demo program

#include <stdio.h>
#include <forms.h>

int main( int argc, char *argv[])
{
   fl_initialize( &argc, argv, "xftest", 0, 0);

   FL_FORM *form = fl_bgn_form( FL_NO_BOX, 400, 300);
   FL_OBJECT *dp =
     fl_add_canvas( FL_NORMAL_CANVAS, 5, 5, 300, 200, "");

   fl_end_form();

   fl_show_form( form, FL_PLACE_FREE, FL_FULLBORDER, "xftest");

   XSync( fl_get_display(), 0);

   printf( "canvas window %d\n", (int) FL_ObjWin( dp));
   printf( "paused, press ENTER to continue\n");
   getchar();

   // Now increase the canvas size to 350x250
   fl_freeze_form( form);
   fl_set_object_geometry( dp, 5, 5, 350, 250);
   fl_unfreeze_form( form);

   XSync( fl_get_display(), 0);

   // Bug manifests as a zero return from FL_ObjWin
   // But only if freeze/unfreeze is used.
   printf( "canvas window %d\n", (int) FL_ObjWin( dp));
   printf( "paused, press ENTER to continue\n");
   getchar();

   return 0;
}

 $ gcc -Wall -o xftest xftest.c -lforms

The program prints the window handle before and after
the canvas size change.   On pre10 and pre11, the
window ID changes, which is no problem:-

 $ ./xftest
 canvas window 341835836
 paused, press ENTER to continue

 canvas window 341835837
 paused, press ENTER to continue

But on pre12 and pre13, the window ID becomes zero:-

 $./xftest
 canvas window 341835836
 paused, press ENTER to continue

 canvas window 0
 paused, press ENTER to continue

The problem only occurs when freeze/unfreeze is used.

--
Paul Nicholson
--