Article # 412, added by Geoworks, historical record
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What is a MemHandle?



Q. I used GrGetBitmap to save the background, but it returns a MemHandle.
   Where can I find the definition for MemHandle. And how to make use
   of the information returned by XYSize?

A. GrGetBitmap returns a MemHandle to a newly allocated memory block
   containing the bitmap. The memory handle is an indirect reference
   to that memory block.

   A MemHandle is a very important type in GEOS; you really need to
   understand it to effectively develop GEOS applications. At a very
   basic level, a MemHandle is just a 16-bit value used to locate a
   memory block. Look in chapter 15 of the Concepts manual to get an
   in-depth discussion of memory management. To access the memory block,
   use MemLock(). This will restrict the block from being moved around
   in memory and return a pointer to the beginning of the block/bitmap.
   When you are finished accessing the block, use MemUnlock to allow
   the block to be movable again (the pointer to the block will now be
   invalid). When you have no more use for the memory block, will have
   to free the block with MemFree().