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Inside Macintosh: More Macintosh Toolbox /

Chapter 1 - Resource Manager / Resource Manager Reference

Resource Manager Routines

Reading and Writing Partial Resources

You can use the ReadPartialResource, WritePartialResource, and SetResourceSize procedures to work with a portion of a large resource that may not otherwise fit in memory.

When using partial resource routines, you should call the SetResLoad procedure, specifying FALSE for the load parameter, before you call GetResource. Using the SetResLoad procedure prevents the Resource Manager from reading the entire resource into memory. Be sure to restore the normal state by calling SetResLoad again, with the load parameter set to TRUE, immediately after you call GetResource.
Then use ReadPartialResource to read a portion of the resource into a buffer and WritePartialResource as needed to write a portion of the resource from a buffer
to disk.

Note that the partial resources routines work with the data in the memory pointed to by the buffer parameter, not the memory referenced through the resource's handle. Therefore, you may experience problems if you have a copy of a resource in memory when you are using the partial resource routines. If you have modified the copy in memory and then access the resource on disk using the ReadPartialResource procedure, ReadPartialResource reads the data on disk, not the data in memory, which is referenced through the resource's handle. Similarly, WritePartialResource writes data from the specified buffer, not from the data in memory, which is referenced through the resource's handle.

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Subtopics

ReadPartialResource

WritePartialResource

SetResourceSize