/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <draw.h>#include <memdraw.h>#include <memlayer.h> intmemlsetrefresh(Memimage *i, Refreshfn fn, void *ptr){	Memlayer *l; 	l = i->layer;	if(l->refreshfn!=nil && fn!=nil){	/* just change functions */		l->refreshfn = fn;		l->refreshptr = ptr;		return 1;	} 	if(l->refreshfn == nil){	/* is using backup image; just free it */		freememimage(l->save);		l->save = nil;		l->refreshfn = fn;		l->refreshptr = ptr;		return 1;	} 	l->save = allocmemimage(i->r, i->chan);	if(l->save == nil)		return 0;	/* easiest way is just to update the entire save area */	l->refreshfn(i, i->r, l->refreshptr);	l->refreshfn = nil;	l->refreshptr = nil;	return 1;}