Q152778: Example Shows How to Pass Objects to FLL

Article: Q152778
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0b
Operating System(s): 
Keyword(s): kbcode
Last Modified: 15-DEC-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0b 
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SUMMARY
=======

Visual FoxPro provides eight new API routines that allow you to manipulate
Visual FoxPro objects and controls. In addition, the Value structure defined in
the Library Construction Kit (LCK) has been expanded to use object references.
This article gives an example showing how to pass and receive object references
within an LCK routine.

MORE INFORMATION
================

The following C code illustrates how to use one of the new API routines, which
requires an object reference (_WGetObjectClientWindow) and returns a handle to
the window containing the passed object. The LCK routine clears the command
button from the window to verify that the program is working as expected.

FoxPro Code
-----------

  * Place the following code in the Click event of a button on a form:
  SET LIBRARY TO clearwind.FLL ADDITIVE
  = CLEARWIND(this)  && we are passing the button object to the C routine
  RELEASE LIBRARY clearwind

C Code
------

  #include <pro_ext.h>

  void FAR ClearObjWin(ParamBlk FAR *parm)
  {
     WHANDLE Wh;
     \\ Note that you are passing the address to the Value structure.
     Wh = _WGetObjectClientWindow(&parm->p[0].val);
     _WClear(Wh);
  };

  \\ Note below that the parameter type is "O" (for Object).
  FoxInfo myFoxInfo[] =
  {
     {"CLEARWIND", (FPFI) ClearObjWin, 1, "O"},
  };

  FoxTable _FoxTable =
  {
     (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
  };

REFERENCES
==========

For more information about building FLLs for Visual FoxPro, please see the
following articles in the Microsoft Knowledge Base:

  Q135709 PRB: Visual C++ Link Error LNK2001: unresolved external symbol

  Q137059 DOCERR: Missing Visual C/C++ "Multithreaded Using DLL" Setting

Additional query words: VFoxWin

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Keywords          : kbcode 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300b
Version           : WINDOWS:3.0b

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