Path: utzoo!attcan!uunet!ogicse!mintaka!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: Multiple GCs sharing fonts vs. XFreeGC
Message-ID: <9004131331.AA26865@lyre.MIT.EDU>
Date: 13 Apr 90 13:31:45 GMT
References: <625@igor.Rational.COM>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: DEC/MIT Project Athena
Lines: 61


    I'm running X.V11R4 with
    fixes 1..9 installed

     Xscope reveals that the first call to
    XFreeGC issued a CloseFont request which released my font_id!

There's something missing here.  XFreeGC does not cause a CloseFont
in the sources I'm looking at (nor should it!).

    Having several GCs using the same font id doesn't seem like too
    radical an idea

No, it's not at all radical -- in fact, it's quite normal.

    Somebody else must have tried this.

You bet.  Just to make sure, I've attached below some patches that
you may apply to examples/Xaw/xcommand.c and test the libraries you're
really using.

    PS:  Why, oh why, doesn't the toolkit manage fonts and XFontStructs?

More than the resource conversion cache does, you mean?  Maybe
you should describe what additional mechanisms you'd like.

	-Ralph.

--------
Test case:  apply the following to examples/Xaw/xcommand.c, making
a new file /tmp/gctest.c.  Each time you press the button, a new
GC will be created and destroyed using a single common font.  Also,
the button will be re-drawn using the same font id.

*** /x/examples/Xaw/xcommand.c	Fri Dec 15 19:37:16 1989
--- /tmp/gctest.c	Fri Apr 13 09:24:28 1990
***************
*** 88,94 ****
  Widget w;
  XtPointer call_data, client_data;
  {
!     fprintf(stdout, "Button Selected.\n");
  }
  
  /*	Function Name: Syntax
--- 88,102 ----
  Widget w;
  XtPointer call_data, client_data;
  {
!     GC gc;
!     XGCValues values;
!     XFontStruct *font;
! 
!     XtVaGetValues(w, XtNfont, (XtArgVal)&font, NULL);
!     values.font = font->fid;
!     gc = XCreateGC(XtDisplay(w), XtWindow(w), GCFont, &values);
!     printf("font id = %x; gc id = %x\n", values.font, gc->gid);
!     XFreeGC(XtDisplay(w),gc);
  }
  
  /*	Function Name: Syntax