Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: Novice question about using raw Xlib for drawing in a widget.
Message-ID: <8901171309.AA11516@LYRE.MIT.EDU>
Date: 17 Jan 89 13:09:48 GMT
References: <5520@phoenix.Princeton.EDU>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: DEC/MIT Project Athena
Lines: 91

> First, if I put the line "<Expose>: draw()\n" in my translation table
> draw() does not end up being called even though "<Enter>: draw()\n"
> does cause draw to be called.  What is the deal?

I dunno.  The following patch to X11R3/examples/Xaw/xcommand.c seems
to do what you and I would expect.  Perhaps you can figure out what
you're missing from this.

*** X11R3/examples/Xaw/xcommand.c
--- /tmp/f.c
***************
*** 1,6 ****
--- 1,7 ----
  #include <stdio.h>
  #include <X11/Intrinsic.h>
  #include <X11/Command.h>
+ #include <X11/StringDefs.h>
  
  static XrmOptionDescRec options[] = {
  {"-label",	"*label",	XrmoptionSepArg,	NULL}
***************
*** 22,33 ****
--- 23,64 ----
      printf( "button was activated.\n" );
  }
  
+ void Exposed(w, event, params, param_count)
+     Widget w;
+     XEvent *event;
+     String *params;
+     Cardinal *param_count;
+ {
+     printf( "button was exposed.\n" );
+ }
  
+ void Draw(w, event, params, param_count)
+     Widget w;
+     XEvent *event;
+     String *params;
+     Cardinal *param_count;
+ {
+     static GC gc;
+     if (gc == NULL) {
+ 	XGCValues values;
+         Arg args[2];
+ 	XtSetArg( args[0], XtNforeground, &values.foreground );
+ 	XtSetArg( args[1], XtNbackground, &values.background );
+ 	XtGetValues( w, args, (Cardinal)2 );
+ 	gc = XtGetGC( w, GCForeground | GCBackground, &values );
+     }
+     XDrawPoint( XtDisplay(w), XtWindow(w), gc,
+ 	        event->xmotion.x, event->xmotion.y );
+ }
+ 
+ 
+ 
  void main(argc, argv)
      unsigned int argc;
      char **argv;
  {
      Widget toplevel;
+     Widget c;
      static XtCallbackRec callbacks[] = {
        { Activate, NULL },
        { NULL, NULL },
***************
*** 42,49 ****
--- 73,95 ----
  
      if (argc != 1) Syntax(argv[0]);
  
+     c =
      XtCreateManagedWidget( "command", commandWidgetClass, toplevel,
  			   args, XtNumber(args) );
+ 
+     {
+ 	static XtActionsRec actions[] = {
+ 	    { "expose", Exposed },
+ 	    { "draw",   Draw },
+ 	};
+ 	XtAddActions( actions, XtNumber(actions) );
+     }
+     XtOverrideTranslations( c,
+ 	XtParseTranslationTable(
+ 	    "<Expose>: expose() \n\
+ 	     <BtnMotion>: draw() "
+ 	)
+     );
      
      XtRealizeWidget(toplevel);
      XtMainLoop();