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Added StructHelper.InitWithSize to simplify the many structures that have to be initialized with their size.

pull/211/head
dahall 2021-01-11 11:16:52 -07:00
parent e23d7d2220
commit 0d732be421
1 changed files with 19 additions and 0 deletions
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19
PInvoke/Shared/StructHelper.cs
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@ -1,5 +1,8 @@
using System;
using System.Linq;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Vanara.Extensions;
namespace Vanara.PInvoke
@ -39,5 +42,21 @@ namespace Vanara.PInvoke
if (count == 0) return new T[0];
return DangerousAddressOf(ref fieldReference).ToArray<T>(count, offset);
}
/// <summary>Creates a new instance of <typeparamref name="T"/> with a size field set to the size of its unmanaged type.</summary>
/// <typeparam name="T">The type to return .</typeparam>
/// <param name="fieldName">
/// Name of the field which is assigned the size. If <see langword="null"/>, the first public or private field is used.
/// </param>
/// <returns>An initialized instance of <typeparamref name="T"/>.</returns>
public static T InitWithSize<T>(string fieldName = null) where T : new()
{
const BindingFlags bf = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
var fi = fieldName is null ? typeof(T).GetOrderedFields(bf).FirstOrDefault() : typeof(T).GetField(fieldName, bf);
var ret = (object)new T();
fi.SetValue(ret, Convert.ChangeType((uint)InteropExtensions.SizeOf<T>(), fi.FieldType));
return (T)ret;
}
}
}