[Help] How can I use C# to create a StdPicture Object for VB6?

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Liu Qian - 26 Aug 2003 10:50 GMT

Hello, all!

I use OleCreatePictureIndirect API to create StdPicture, and the return is
S_OK, but the result seem not correct.

Here is my code:

[DllImport("olepro32.dll", SetLastError=true)]
internal static extern int OleCreatePictureIndirect(ref PICTDESC pPictDesc,
ref System.Guid riid, bool fOwn, ref stdole.IPictureDisp ppvObj);

internal struct PICTDESC{
public long cbSizeOfStruct;
public long picType;
public long hPic;
public long hpal;
};

public StdPicture GetImage(int hHandle){

PICTDESC pd = new PICTDESC();
pd.cbSizeOfStruct = 144;//Marshal.SizeOf(pd);
pd.hPic = hHandle;
pd.hpal = 0;
pd.picType = 1; // bitmap

// Fill in magic IPicture GUID {7BF80980-BF32-101A-8BBB-00AA00300CAB}
System.Guid iidIPicture = new
Guid("7BF80980-BF32-101A-8BBB-00AA00300CAB");

stdole.IPictureDisp ipic = null;
int nResult = OleCreatePictureIndirect(ref pd, ref iidIPicture, true, ref
ipic);

//System.Diagnostics.Trace.WriteLine("Error: " +
Marshal.GetLastWin32Error());

return (StdPicture)ipic;
}

The call of OleCreatePictureIndirect is OK, but the contents of ipic are
always "0". Anyone can help me or give some advises?

Thanks very much!

chian

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Mattias Sj?gren - 26 Aug 2003 21:57 GMT

>[DllImport("olepro32.dll", SetLastError=true)]
>internal static extern int OleCreatePictureIndirect(ref PICTDESC pPictDesc,
[quoted text clipped - 6 lines]
> public long hpal;
> };

Your PICTDESC structure declaration is incorrect. Try it like this
instead.

[DllImport("olepro32.dll", PreserveSig=false)]
internal static extern void OleCreatePictureIndirect(ref PICTDESC
pPictDesc, ref System.Guid riid, bool fOwn, out stdole.IPictureDisp
ppvObj);

internal struct PICTDESC{
public int cbSizeOfStruct;
public int picType;
public IntPtr hPic;
public IntPtr hpal;
public int _pad;
};

> pd.cbSizeOfStruct = 144;//Marshal.SizeOf(pd);

The structure size is definitely not 144 bytes. You better use
Marshal.SizeOf instead.

Mattias

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Liu Qian - 27 Aug 2003 02:15 GMT

OK, Thanks Mattias.

The code worked correctlly, thank you very much.

chian

> >[DllImport("olepro32.dll", SetLastError=true)]
> >internal static extern int OleCreatePictureIndirect(ref PICTDESC pPictDesc,
[quoted text clipped - 29 lines]
>
> Mattias

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[Help] How can I use C# to create a StdPicture Object for VB6?

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