Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!mintaka!bloom-beacon!vaxeline!bootsie!olson
From: olson@bootsie.uucp (Eric K. Olson)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Is this possible with the Resource Manager?
Message-ID: <1991Feb17.110259.12499@bootsie.uucp>
Date: 17 Feb 91 11:02:59 GMT
References: <1CE00001.ed5n0r@tbomb.ice.com> <1991Feb17.041728.11518@bootsie.uucp>
Organization: Lexington Software Design, Lexington, MA
Lines: 96

Well, I went ahead and brute-forced it.

The following code allows me to load the Resource data off the disk, even if
the resource is currently loaded and in use (such as 'MENU' resources of the
currently running application).

Unfortunately, it uses things that are likely to break:  internal structures
of the Resource Manager, and the TopMapHndl low-memory global.  I don't know
if these things are likely to change soon, or if they are available under AU/X.

Isn't there a better way?  Is this what AddReference() once did?

typedef struct resMapHeaderRec {
	long			dataOffset;
	long			mapOffset;
	long			dataLength;
	long			mapLength;
} resMapHeaderRec;
 
typedef struct resMapRec {
	resMapHeaderRec		header;
	struct resMapRec * *	nextMap;
	short			refNum;
	short			attrib;
	unsigned short		typeOffset;
	unsigned short		nameOffset;
} resMapRec, *resMapPtr, **resMapHandle;
	
typedef struct resMapEntryRec {
	short			resID;
	unsigned short		nameOffset;
	unsigned long		lengthOffset;
	Handle			resHandle;
} resMapEntryRec, *resMapEntryPtr, **resMapEntryHandle;
 
Handle	GetResDataFromDisk(type,id)
	ResType			type;
	short			id;
{
	Handle			onDiskHand;
	unsigned long		resMapOffset;
	resMapEntryPtr		resMapEntry;
	resMapPtr		resMap;
	short			inMemRef;
	Handle			inMemHandle;
	
	SetResLoad(FALSE);
	inMemHandle = GetResource(type, id);
	SetResLoad(TRUE);
	if (*inMemHandle == NULL) {
		inMemRef = HomeResFile(inMemHandle);
		resMapOffset = RsrcMapEntry(inMemHandle);
	
		resMap = (resMapPtr) *TopMapHndl;

		/* Find the appropriate resource map */
		
		while (resMap->refNum != inMemRef) {
			resMap = *(resMap->nextMap);
			if (resMap==NULL) return NULL;
			}
		
		resMapEntry = (resMapEntryPtr) (((Ptr) resMap) + resMapOffset);
		
		if (resMapEntry->resHandle!=inMemHandle) return NULL;
		
		DetachResource(inMemHandle);	/* resMapEntry->resHandle = NULL; */

		onDiskHand = GetResource(type, id);
		
		if (onDiskHand != NULL) {
			DetachResource(onDiskHand);
			HNoPurge(onDiskHand);
			}
		
		/* Reattach the old resource handle */

		resMapEntry->resHandle = inMemHandle;
		}
	else {
		/* The normal GetResource case */

		onDiskHand = GetResource(type, id);

		if (onDiskHand != NULL) {
			DetachResource(onDiskHand);
			HNoPurge(onDiskHand);
			}
		}
	}

-- 
Eric K. Olson, Editor, Prepare()      NOTE:     olson@bootsie.uucp doesn't work
Lexington Software Design             Internet: olson@endor.harvard.edu
72A Lowell St., Lexington, MA  02173  Uucp:     harvard!endor!olson
(617) 863-9624                        Bitnet:   OLSON@HARVARD