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From: mouse@lightning.mcrcim.mcgill.EDU (der Mouse)
Newsgroups: comp.windows.x
Subject: Re:  Problems freeing an XFontStruct
Message-ID: <9104130157.AA08644@lightning.McRCIM.McGill.EDU>
Date: 13 Apr 91 01:57:37 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 45

> I'm having problems freeing an XFontStruct, here's the code:

> 	GC gc;
> 	XFontStruct *fsp;

> 	gc = XCreateGC(dpy, win, 0, 0);
> 	fsp = XQueryFont(dpy, XGContextFromGC(gc));
> 	XFreeFont(dpy, fsp);

Without prototypes in scope, that first call is wrong (it's passing two
ints instead of an unsigned long and an XGCValues pointer).  But that
is probably not related.

> This generates the following protocol error:

> X Error of failed request:  BadFont (invalid Font parameter)
>   Major opcode of failed request:  46 (X_CloseFont)
>   Resource id in failed request:  0x1500002
>   Serial number of failed request:  6
>   Current serial number in output stream:  11

> I presume because the font ID in the XFontStruct is actually the
> graphics context ID and XFreeFont() assumes it's a font ID.

Most likely.

> So is it possible to free a font structure obtained using a GC rather
> than a font ID?

XFreeFont() is probably not what you want.  XFreeFont() not only frees
the XFontStruct, it also unloads the font.  You probably don't want to
do that; XQueryFont() does not load a font, it merely queries an
already-loaded font.  To just free the XFontStruct, the Xlib document
says you should use XFreeFontInfo().

There appears to be no way to unload a font for which you no longer
have an XFontStruct; while aesthetically unpleasant, this does not
really strike me as a problem.  (If you really must, you can use
XQueryFont to get something to call XFreeFont with, though it seems
rather inefficient.)

					der Mouse

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			new: mouse@larry.mcrcim.mcgill.edu