MAYER-A@RICEVM1.BITNET (David Mayer) (07/20/90)
In article <1990Jul17.172044.20361@Neon.Stanford.EDU>, commons@Sunburn.Stanford.EDU (Peter Commons) says: > >I'm currently working on a new multi-user game for the Mac. In thinking about >how I would like my save file to look, it would be very convenient to have >one resource with the main data and one resource with the data for each player >(rather than have all the data sequentially laid out in the data fork) because >the game will only need to look at one player's info at a time. > >Can I do this? If so, should I use my own (non-reserved) resource name? And if >I define my own resource type, how do I specify it's length (or does it >automatically make it as long as the handle I pass it when I call AddResource? > >Thanks in advance. WELL, I have a related question. It may be more of a Pascal question than a Macintosh question, though. I would like to retrieve the contents of a (rather long) array. A resource of my own type seems like a logical structure for this. I know how to load a resource into memory, but I don't see how then to store the contents into an array I've declared... I would appreciate any suggestions or better ideas. Thanks! --David
souka@uh.msc.umn.edu (Omar Souka) (07/20/90)
> WELL, > > I have a related question. It may be more of a Pascal question than a > Macintosh question, though. I would like to retrieve the contents > of a (rather long) array. A resource of my own type seems > like a logical structure for this. > > I know how to load a resource into memory, but I don't see how then to > store the contents into an array I've declared... > > I would appreciate any suggestions or better ideas. Thanks! > > --David The resource fork is a great place to store nearly any type of data. Here is a sketch of what many programs do. 1. Create a new resource in Resedit. It doesn't have to have anything in it right now but a name (try to make the name unique) and a resource number. Writing to the resource. 1. Call GetResource to get a handle to your resource. 2. If its the first time that your writing to it, you must call SizeHandle to increase the size of the handle to the size of whatever you are going to store. 3. Then simply BlockMove the contents of your data structure into the resource. In C, it would look something like this: BlockMove(array,*ResourceHandle,number_of_bytes); or generically BlockMove(source pointer, destination pointer, # of bytes) This operation will stick the raw bytes of your array into your resource. 4. Call ChangedResource 5. Call WriteResource Reading from the resource 1. Call GetResource 2. If you need to know how big the handle is call HandleSize 3. BlockMove from the resource into your array BlockMove(*ResourceHandle,array,number_of_bytes); In Pascal it would look something like this (just a guess, I don't do Pascal) BlockMove(ResourceHandle^,@array,number_of_bytes) What's great about this technique is that you can store very complicated data structures this way and not really worry about what the structure looks like. If anyone is interested in seeing some actual source, just E-Mail me.
philip@Minnie.Stanford.EDU (Philip Machanick) (07/23/90)
In article <2172@uc.msc.umn.edu>, souka@uh.msc.umn.edu (Omar Souka) writes: > > I have a related question. It may be more of a Pascal question than a > > Macintosh question, though. I would like to retrieve the contents > > of a (rather long) array. A resource of my own type seems > > like a logical structure for this. > > > > I know how to load a resource into memory, but I don't see how then to > > store the contents into an array I've declared... > > > > I would appreciate any suggestions or better ideas. Thanks! [...] > Reading from the resource > > 1. Call GetResource > > 2. If you need to know how big the handle is call HandleSize > > 3. BlockMove from the resource into your array > > BlockMove(*ResourceHandle,array,number_of_bytes); > > In Pascal it would look something like this (just a guess, I don't do Pascal) > > BlockMove(ResourceHandle^,@array,number_of_bytes) > Why not store the result of GetResource directly into the array? You would have to use the array through a handle, e.g., in Pascal: type arrayPtr = ^arrayType; arrayHdl = ^arrayPtr; var data : arrayHdl; begin data := arrayHdl(GetResource(...)); Saves you a blockmove (why copy data unnecessarily?). Philip Machanick philip@pescadero.stanford.edu
boerned@mist.CS.ORST.EDU (Dan Boerner) (07/23/90)
In his response Philip asks
> Why not store the result of GetResource directly into the array?
I believe the answer is that GetResource allocates memory for a resource only
once. The second time you call GetResource, it will return a handle to the
same memory block as it did the first time. Therefore, you must copy the
results of GetResource into a different block of memory for each different
copy of the resource you want.
Dan Boerner
boerned@cs.orst.edu
Oregon State Universitysstorkel@dvlseq.oracle.com (Scott Storkel) (07/24/90)
In article <19475@orstcs.CS.ORST.EDU> boerned@mist.CS.ORST.EDU (Dan Boerner) writes: >In his response Philip asks > >> Why not store the result of GetResource directly into the array? > >I believe the answer is that GetResource allocates memory for a resource only >once. The second time you call GetResource, it will return a handle to the >same memory block as it did the first time. Therefore, you must copy the >results of GetResource into a different block of memory for each different >copy of the resource you want. > Sorry for jumping into the middle of this discussion. Did somebody say something about multiple uses? The correct way to do what Philip suggests is to call DetachResource and then use the handle as a handle to an array. By calling DetachResource, you make the resource manager "forget" about the resource. That way you could call GetResource again to get a new copy of the resource (don't know why you'd want to do that) and the resource manager won't release the memory out from under you (if you close the resource file for example). -- Scott Storkel