Added StructHelper with methods to get pointers for field values.

PInvoke/Shared/StructHelper.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Runtime.CompilerServices;
+using Vanara.Extensions;
+
+namespace Vanara.PInvoke
+{
+	/// <summary>Helper methods for structures.</summary>
+	public static class StructHelper
+	{
+		/// <summary>Gets the address of a reference.</summary>
+		/// <typeparam name="T">The unmanaged value type to convert.</typeparam>
+		/// <param name="target">The target value.</param>
+		/// <returns>The address of <paramref name="target"/>.</returns>
+		/// <remarks>This address will only remain valid if the target value or its encapsulating type are pinned.</remarks>
+		public static IntPtr DangerousAddressOf<T>(ref T target) where T : unmanaged
+		{
+			unsafe
+			{
+				fixed (T* p = &target)
+					return (IntPtr)p;
+			}
+		}
+
+		/// <summary>Converts a field reference to array. Used when a structure defines an ANYSIZE array as the last field.</summary>
+		/// <typeparam name="T">The unmanaged type to convert.</typeparam>
+		/// <param name="fieldReference">A reference to the field value.</param>
+		/// <param name="count">The number of items in the array.</param>
+		/// <param name="offset">The offset from the field value at which to start extracting the array.</param>
+		/// <returns>An <paramref name="count"/> item array of values of <typeparamref name="T"/>.</returns>
+		/// <remarks>
+		/// Properties defined with this can only be safely used when the structure has been marshaled via a dynamic memory block and not
+		/// when marshaled directly.
+		/// </remarks>
+#if !(NET20 || NET35 || NET40)
+		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+#endif
+		public unsafe static T[] FieldToArray<T>(ref T fieldReference, int count, int offset = 0) where T : unmanaged
+		{
+			if (count == 0) return new T[0];
+			return DangerousAddressOf(ref fieldReference).ToArray<T>(count, offset);
+		}
+	}
+}