Shell IDList Arrayについて

typedef struct _IDA{
    UINT cidl;
    UINT aoffset[1];
}CIDA,*LPIDA

// Create parent folder pidl
IntPtr ipShellFolder = IntPtr.Zero;
IntPtr ipParentFolderPIDL = IntPtr.Zero;
ipParentFolderPIDL = Win32Api.ILCreateFromPath(Path.GetDirectoryName(files[0]));

// SHBindToParent
IntPtr ptrParent = IntPtr.Zero;
ShellApi.SHGetDesktopFolder(out ptrParent);
//			IntPtr pidlRelative = IntPtr.Zero;
//			ShellLib.ShellApi.SHBindToParent(
//				ipParentFolderPIDL,
//				ShellLib.ShellGUIDs.IID_IShellFolder,
//				out ptrParent,
//				ref pidlRelative);
// Create IShellFolder object
Type shellFolderType = ShellLib.ShellFunctions.GetShellFolderType();
Object obj =Marshal.GetTypedObjectForIUnknown(
	ptrParent,shellFolderType);
ShellLib.IShellFolder ishellParent = (ShellLib.IShellFolder)obj;

ishellParent.BindToObject(ipParentFolderPIDL,IntPtr.Zero,
	ShellGUIDs.IID_IShellFolder,out ptrParent);

obj =Marshal.GetTypedObjectForIUnknown(
	ptrParent,shellFolderType);
ishellParent = (ShellLib.IShellFolder)obj;
---------------------------------------------------------------------
IShellFolderのBindToObjectの宣言
// Retrieves an IShellFolder object for a subfolder.
// Return value: error code, if any
[PreserveSig]
Int32 BindToObject( 
	IntPtr pidl,				// Address of an ITEMIDLIST structure (PIDL) that identifies the subfolder.
	IntPtr pbc,					// Optional address of an IBindCtx interface on a bind context object to be 
	/*object pbc,*/
	// used during this operation.
	Guid riid,					// Identifier of the interface to return. 
	out IntPtr ppv);			// Address that receives the interface pointer.

// ※　長すぎるのでIShellFolderやShellApiなどの物については省略させていただきました。
[StructLayout(LayoutKind.Sequential)]
public struct CIDA
{
	/// <summary>
	///  Number of PIDLs that are being transferred, not counting the parent folder.
	/// </summary>
	public uint cidl;

	/// <summary>
	/// An array of offsets, relative to the beginning of this structure. The array contains
	/// cidl+1 elements. The first element of aoffset contains an offset to the fully-qualified
	/// PIDL of a parent foloder. If this PIDL is empty, the parent folder is the desktop.
	/// Each of the remaining elements of the array contains an offset to one of the PIDLs to be 
	/// transferred. ALL of these PIDLs are relative to the PIDL of the parent folder.
	/// </summary>
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=1)]
	public uint[] aoffset;
}
public unsafe static object[] CreateITEMIDLISTFromFileNames(string[] files)
{
	// Create parent folder pidl
	IntPtr ipShellFolder = IntPtr.Zero;
	IntPtr ipParentFolderPIDL = IntPtr.Zero;
	ipParentFolderPIDL = Win32Api.ILCreateFromPath(Path.GetDirectoryName(files[0]));

	// SHBindToParent
	IntPtr ptrParent = IntPtr.Zero;
	ShellApi.SHGetDesktopFolder(out ptrParent);
//			IntPtr pidlRelative = IntPtr.Zero;
//			ShellLib.ShellApi.SHBindToParent(
//				ipParentFolderPIDL,
//				ShellLib.ShellGUIDs.IID_IShellFolder,
//				out ptrParent,
//				ref pidlRelative);
	// Create IShellFolder object
	Type shellFolderType = ShellLib.ShellFunctions.GetShellFolderType();
	Object obj =Marshal.GetTypedObjectForIUnknown(
		ptrParent,shellFolderType);
	ShellLib.IShellFolder ishellParent = (ShellLib.IShellFolder)obj;

	ishellParent.BindToObject(ipParentFolderPIDL,IntPtr.Zero,
		ShellGUIDs.IID_IShellFolder,out ptrParent);

	obj =Marshal.GetTypedObjectForIUnknown(
		ptrParent,shellFolderType);
	ishellParent = (ShellLib.IShellFolder)obj;


	// Copy buffer
	object[] apidl = new object[files.Length+1];
	byte[] buffer = new byte[Win32Api.ILGetSize(ipParentFolderPIDL)];
	Marshal.Copy(ipParentFolderPIDL,buffer,0,buffer.Length);
	apidl[0] = buffer;
	for(int i=0;i<files.Length;i++)
	{
		string file = files[i];
		// Create relative file pidl to parent folder
		uint pchEaten = 0,pdwAttributes = 0;
		IntPtr ipRelativePIDL = IntPtr.Zero;
		ishellParent.ParseDisplayName(IntPtr.Zero,IntPtr.Zero,
			file,ref pchEaten,out ipRelativePIDL,ref pdwAttributes);
		// Test
		System.Text.StringBuilder sb = new System.Text.StringBuilder(1024);
	
		// Get ITEMIDLIST buffer
		buffer = new byte[Win32Api.ILGetSize(ipRelativePIDL)];
		Marshal.Copy(ipRelativePIDL,buffer,0,buffer.Length);
		// Free ITEMIDLIST
		Win32Api.ILFree(ipRelativePIDL);
		// Copy buffer
		apidl[i+1] = buffer;
	}
	// Free the ITEMLIST
	Win32Api.ILFree(ipParentFolderPIDL);
	// Free the IShellFolder object
	Marshal.ReleaseComObject(ishellParent);
	return apidl;
}

public static byte[] CreateShellIDListArray(string[] files)
{
	int sizeOfCIDA,sizeOfRemainingOffsets,sizeOfITEMIDLIST;

	IntPtr ipGlobal = IntPtr.Zero;
	object[] ITEMIDLISTs = null;

	// Get ITEMIDLIST from files
	ITEMIDLISTs = CreateITEMIDLISTFromFileNames(files);

	// Calculate size
	sizeOfCIDA = Marshal.SizeOf(typeof(CIDA));
	sizeOfRemainingOffsets = ITEMIDLISTs.Length * IntPtr.Size;
	sizeOfITEMIDLIST = 0;
	for(int i=0;i<ITEMIDLISTs.Length;i++)
	{
		byte[] b = (byte[])ITEMIDLISTs[i];
		sizeOfITEMIDLIST+=b.Length;
	}

	// Alloc and get pointer of global memory
	ipGlobal = Marshal.AllocHGlobal(sizeOfCIDA + sizeOfRemainingOffsets + sizeOfITEMIDLIST);

	// Build structure in global memory
	CIDA cida = new CIDA();
	cida.cidl = (uint)(ITEMIDLISTs.Length+1);
	cida.aoffset = new uint[cida.cidl];
	cida.aoffset[0] = (uint)(sizeOfCIDA + sizeOfRemainingOffsets);
	int offset = 0;
	for(int i=0;i<ITEMIDLISTs.Length; i++)
	{
		cida.aoffset[i]=(uint)(sizeOfCIDA + sizeOfRemainingOffsets + offset);
		offset +=((byte[])ITEMIDLISTs[i]).Length;
	}
	cida.aoffset[cida.cidl-1] = 0;

	Marshal.StructureToPtr(cida,ipGlobal,true);

//			int offset = ((byte[])ITEMIDLISTs[0]).Length;
//			int[] remainingOffsets = new int[ITEMIDLISTs.Length];
//			for(int i=0;i<ITEMIDLISTs.Length-1; i++)
//			{
//				remainingOffsets[i]=(int)(sizeOfCIDA + sizeOfRemainingOffsets + offset);
//				offset +=((byte[])ITEMIDLISTs[i+1]).Length;
//			}
//			remainingOffsets[ITEMIDLISTs.Length-1]=0;
//
//			Marshal.Copy(remainingOffsets,0,(IntPtr)(ipGlobal.ToInt32() + sizeOfCIDA),remainingOffsets.Length);

	// Copy to ITEMIDLISTs
	offset = ipGlobal.ToInt32() + sizeOfCIDA + sizeOfRemainingOffsets;
	for(int i=0;i<ITEMIDLISTs.Length;i++)
	{
		byte[] b = (byte[])ITEMIDLISTs[i];
		Marshal.Copy(b,0,(IntPtr)offset,b.Length);
		offset+=b.Length;
	}

	byte[] result = new byte[sizeOfCIDA + sizeOfRemainingOffsets + sizeOfITEMIDLIST];
	Marshal.Copy(ipGlobal,result,0,result.Length);
	return result;
}