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jjones7947
Joined: 17 Mar 2010
Posts: 2
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 Posted: Wed Mar 17, 2010 2:14 pm Post subject: Problem getting correct parameter types for P/Invoke call |
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Trying to Interop a functionality from the Outside In API from Oracle.
Have the following function:
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SCCERR EXOpenExport { VTHDOC hDoc, VTDWORD dwOutputId, VTDWORD dwSpecType, VTLPVOID pSpec, VTDWORD dwFlags, VTSYSPARAM dwReserved, VTLPVOID pCallbackFunc, VTSYSPARAM dwCallbackData, VTLPHEXPORT phExport);
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From the header files I reduced the parameters to:
typedef VTSYSPARAM VTHDOC, VTLPHDOC *
typedef DWORD_PTR VTSYSPARAM
typedef unsigned long DWORD_PTR
typedef unsigned long VTDWORD
typedef VTVOID* VTLPVOID
#define VTVOID void
typedef VTHDOC VTHEXPORT, *VTLPEXPORT
Documentation says that this type is a non-filesystem handle
These are for 32 bit windows
Going through the header files, the example programs, and the documentation I found:
1. That pSpec could be a pointer to a buffer or NULL, so I set it to a IntPtr.Zero (documentation).
2. That dwFlags and dwReserved according to the documentation "Must be set by the developer to 0".
3. That pCallbackFunc can be set to NULL if I don't want to handle callbacks.
6. That the last two are based on structs that I wrote C# wrappers for using the [StructLayout(LayoutKind.Sequential)]. Then instantiated an instance and generated the parameters by first creating a IntPtr with Marshal.AllocHGlobal(Marshal.SizeOf(instance)), then getting the address value which is passed as a uint for dwCallbackData and a IntPtr for phExport.
The final parameter list is as follows:
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phDoc as a IntPtr which was loaded with an address by the DAOpenDocument function called before
dwOutputId as uint set to 1535 which represents FI_JPEGFIF
dwSpecType as int set to 2 which represents IOTYPE_ANSIPATH
pSpec as an IntPtr.Zero where the output will be written
dwFlags as uint set to 0 as directed
dwReserved as uint set to 0 as directed
pCallbackFunc as IntPtr set to NULL as I will handle results
dwCallBackDate as uint the address of a buffer for a struct
phExport as IntPtr to another struct buffer
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still get an undefined error from the API. By that I mean that when I call the function through P/Invoke it returns 961 which does not correlate to any of the errors defined in the header files. Past experience says that I get this result when my choice of parameter types is incorrect.
Jim |
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Paul.Martin
Joined: 03 Feb 2010
Posts: 83
Location: Cambridgeshire
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| Posted: Thu Mar 18, 2010 4:10 pm Post subject: |
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| I've not used the Oracle Outside In API so I can't say with any confidence, but looking at the specification - if you set pSpec to NULL (IntPtr.Zero) you need to pass a callback function in pCallbackFunc that will handle a dwCommandID of EX_CALLBACK_ID_CREATENEWFILE. |
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jjones7947
Joined: 17 Mar 2010
Posts: 2
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| Posted: Thu Mar 18, 2010 7:11 pm Post subject: |
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| Ok will give that a try |
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Paul.Martin
Joined: 03 Feb 2010
Posts: 83
Location: Cambridgeshire
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| Posted: Mon Mar 29, 2010 5:24 pm Post subject: |
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| Did you get any success with this? |
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