mirror of https://github.com/dahall/Vanara.git
68 lines
3.0 KiB
C#
68 lines
3.0 KiB
C#
using System;
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using System.Runtime.InteropServices;
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namespace Vanara.InteropServices
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{
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/// <summary>Provide a IDispatch-based (e.g. late-bound) access to a COM object. Use <see cref="Invoke"/> to work with the object.</summary>
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public class SafeIDispatch : ComReleaser<dynamic>
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{
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/// <summary>Initializes a new instance of the <see cref="SafeIDispatch"/> class.</summary>
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/// <param name="target">The target object which must be a raw COM object.</param>
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public SafeIDispatch(object target) : base(target)
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{
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if (!Marshal.IsComObject(target))
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throw new ArgumentException("The target object must be a COM object");
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RawPointer = GetRawPointer(target);
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}
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/// <summary>Gets the pointer to the IDispatch instance.</summary>
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/// <value>A pointer to the IDispatch instance.</value>
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public IntPtr RawPointer { get; }
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/// <summary>Determines whether the specified <see cref="System.Object"/>, is equal to this instance.</summary>
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/// <param name="other">The <see cref="System.Object"/> to compare with this instance.</param>
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/// <returns><see langword="true"/> if the specified <see cref="System.Object"/> is equal to this instance; otherwise, <see langword="false"/>.</returns>
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public bool Equals(ComReleaser<dynamic> other) => other?.Item is null || Item is null ? false : (bool)(RawPointer == GetRawPointer(other.Item));
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/// <summary>Determines whether the specified <see cref="System.Object"/>, is equal to this instance.</summary>
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/// <param name="obj">The <see cref="System.Object"/> to compare with this instance.</param>
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/// <returns><see langword="true"/> if the specified <see cref="System.Object"/> is equal to this instance; otherwise, <see langword="false"/>.</returns>
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public override bool Equals(object obj) => obj is ComReleaser<dynamic> o ? Equals(o) : base.Equals(obj);
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/// <summary>Returns a hash code for this instance.</summary>
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/// <returns>A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.</returns>
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public override int GetHashCode() => RawPointer.ToInt32();
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/// <summary>
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/// Method to encapsulate operations against the late-bound COM object. The caller must handle any exceptions that may result as part
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/// of the operation.
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/// </summary>
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/// <param name="action">A method that performs work against the late-bound COM object.</param>
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public void Invoke(Action<dynamic> action) => action.Invoke(Item);
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private static IntPtr GetRawPointer(object target)
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{
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var result = IntPtr.Zero;
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try
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{
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#if NETSTANDARD2_0
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result = Marshal.GetComInterfaceForObject(target, typeof(IDispatch));
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#else
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result = Marshal.GetIDispatchForObject(target);
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#endif
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}
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finally
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{
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// Decrement reference count added by call to GetIDispatchForObject
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if (result != IntPtr.Zero)
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Marshal.Release(result);
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}
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return result;
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}
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#if NETSTANDARD2_0
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[ComImport, Guid("00020400-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
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private interface IDispatch { }
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#endif
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}
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} |