Sometimes the functions do not return the information you need the way you want it. Typical example is combining two integer(2-byte) values specifying the mouse position into one 4-byte value. Another case is telling you that if bit 29 is on it means something. Also, you may receive a Long value that is the address of a structure.

Combining or separating values does not need any description. APIMacro.bas you may find on our site (www.geocities.com/SiliconValley/Lab/1632/) contains all functions you need to have.

To check if bit N of Value is on use the following:

If Value and (2^N) then ...

To set a bit on:

Value = Value Or 2^N

To set a bit off:

Value = Value And Not 2^N

If you set and get the state of a bit you know beforehand, its much faster to replace 2^10 with 1024. This way VB won't have to calculate it itself (VB "hates" ^).

If you receive a pointer to a type, then you must do a bit more. To get the info, you use CopyMem function. Here is the declaration:

Declare Sub CopyMem Lib "kernel32" Alias "RtlMoveMemory"
(pDest As Any, pSource As Any, ByVal ByteLen As Long)

If you receive a pointer to RECT type in the Long variable Addr, use the following:

Dim Info As Rect
Call CopyMem(Info, ByVal Addr, Len(Info))

Note the ByVal keyword. Now, if you need to put the information back, use:

Call CopyMem(ByVal Addr, Info, Len(Info))

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Copyright (c) 1998, Billy&George Software and Peter Dimitrov
Revised March 2000