Re: Converting a C struct to C# for a P/Invoke call (struct in structs and unions)
- From: Tom Hellström <nospamplease@xxxxxxxx>
- Date: 14 Jul 2005 07:10:03 -0500
"David Browne" <davidbaxterbrowne no potted meat@xxxxxxxxxxx> wrote:
>
>"Tom Hellström" <nospamplease@xxxxxxxx> wrote in message
>news:42cfdc72$1_3@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> Hi, i want to make a call to a dll and I need to pass a pointer that then
>> gets
>> converted to a struct
>> via the Marshal.PtrToStructure method. The thing is, the struct is a bit
>> complicated.
>>
>> I need some tip on how to get around the union parts and also how to deal
>> with
>> the #if's at the bottom.
>> Any ideas?
>>
>>
>> typedef struct _devicemode {
>> BCHAR dmDeviceName[CCHDEVICENAME];
>> WORD dmSpecVersion;
>> WORD dmDriverVersion;
>> WORD dmSize;
>> WORD dmDriverExtra;
>> DWORD dmFields;
>> union {
>> struct {
>> short dmOrientation;
>> short dmPaperSize;
>> short dmPaperLength;
>> short dmPaperWidth;
>> short dmScale;
>> short dmCopies;
>> short dmDefaultSource;
>> short dmPrintQuality;
>> };
>> POINTL dmPosition;
>> DWORD dmDisplayOrientation;
>> DWORD dmDisplayFixedOutput;
>> };
>>
>> short dmColor;
>> short dmDuplex;
>> short dmYResolution;
>> short dmTTOption;
>> short dmCollate;
>> BYTE dmFormName[CCHFORMNAME];
>> WORD dmLogPixels;
>> DWORD dmBitsPerPel;
>> DWORD dmPelsWidth;
>> DWORD dmPelsHeight;
>> union {
>> DWORD dmDisplayFlags;
>> DWORD dmNup;
>> }
>> DWORD dmDisplayFrequency;
>> #if(WINVER >= 0x0400)
>> DWORD dmICMMethod;
>> DWORD dmICMIntent;
>> DWORD dmMediaType;
>> DWORD dmDitherType;
>> DWORD dmReserved1;
>> DWORD dmReserved2;
>> #if (WINVER >= 0x0500) || (_WIN32_WINNT >= 0x0400)
>> DWORD dmPanningWidth;
>> DWORD dmPanningHeight;
>> #endif
>> #endif /* WINVER >= 0x0400 */
>> } DEVMODE;
>>
>> have a nice summer
>> ///. Tom H
>>
>>
>
>
>Beyond a certian threshold of gruesomeness you might be better off using the
>struct in a managed C++ wrapper. The wrapper can interact natively with the
>struct and provide managed code with access to the data.
>
>Another option is to figure out the size of the struct and just use a
>managed byte array. Then use BitConverter and procedural logic to read and
>write the struct. A hybrid approach is to break the struct into several
>regions and procedurally marshal them. These approaches use pure C#, but
>ironically require a higher level of understanding of C/C++ structs and
>unmanaged memory than the C++ wrapper approach, since the C++ compiler
>understands the struct for you.
>
>David
>
>
Well, I got hold of a C# version of the struct, but I ran into some other
problems, where
your tip about splitting it up and marshaling the separate pices worked fine.
Thanks,
///. Tom
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- References:
- Converting a C struct to C# for a P/Invoke call (struct in structs and unions)
- From: Tom Hellström
- Re: Converting a C struct to C# for a P/Invoke call (struct in structs and unions)
- From: David Browne
- Converting a C struct to C# for a P/Invoke call (struct in structs and unions)
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