mirror of https://github.com/dahall/Vanara.git
61 lines
2.2 KiB
C#
61 lines
2.2 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using Vanara.Extensions;
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using Vanara.InteropServices;
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namespace Vanara.PInvoke
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{
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/// <summary>
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/// Interface that identifies a structure containing only a 4-byte size field followed by a pointer to an array of <typeparamref name="T"/>.
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/// </summary>
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/// <typeparam name="T">A marshalable structure.</typeparam>
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public interface IArrayStruct<T> where T : struct { }
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/// <summary>Extension methods for <see cref="IArrayStruct{T}"/>.</summary>
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public static class IArrayStructExtensions
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{
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/// <summary>Gets the array from an <see cref="IArrayStruct{T}"/> instance.</summary>
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/// <typeparam name="T">The type of the array.</typeparam>
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/// <param name="ias">The <see cref="IArrayStruct{T}"/> instance.</param>
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/// <returns>The array contained in the instance.</returns>
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public static T[] GetArray<T>(this IArrayStruct<T> ias) where T : struct
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{
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using var pin = new PinnedObject(ias);
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return ((IntPtr)pin).ToArray<T>((int)((IntPtr)pin).ToStructure<uint>(), sizeof(uint));
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}
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}
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/// <summary>Allows marshaling of arrays in place of a structure supporting <see cref="IArrayStruct{T}"/>.</summary>
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/// <typeparam name="T">The type of the array element.</typeparam>
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/// <seealso cref="Vanara.InteropServices.IVanaraMarshaler"/>
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public class IArrayStructMarshaler<T> : IVanaraMarshaler where T : struct
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{
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public static readonly int hSz = sizeof(uint);
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/// <inheritdoc/>
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public SizeT GetNativeSize() => hSz + IntPtr.Size;
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/// <inheritdoc/>
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public SafeAllocatedMemoryHandle MarshalManagedToNative(object managedObject)
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{
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if (managedObject is IEnumerable<T> ias)
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{
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var cnt = ias.Count();
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var mem = new SafeHGlobalHandle(hSz + InteropExtensions.SizeOf<T>() * cnt);
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mem.Write(cnt);
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mem.Write(ias, true, hSz);
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return mem;
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}
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throw new ArgumentException("Unexpected type. Value must be of IEnumerable<T>.");
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}
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/// <inheritdoc/>
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public object MarshalNativeToManaged(IntPtr pNativeData, SizeT allocatedBytes)
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{
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if (pNativeData == default) return new T[0];
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var cnt = pNativeData.ToStructure<uint>();
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return pNativeData.ToArray<T>((int)cnt, hSz, allocatedBytes);
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}
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}
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} |