mirror of https://github.com/dahall/Vanara.git
67 lines
3.1 KiB
C#
67 lines
3.1 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>Factory for creating <see cref="ComReleaser{T}"/> objects.</summary>
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public static class ComReleaserFactory
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{
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/// <summary>Factory method to create a <see cref="ComReleaser{TObj}"/> using type inference.</summary>
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/// <typeparam name="TObj">The type of the object.</typeparam>
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/// <param name="obj">The object.</param>
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/// <returns>A <see cref="ComReleaser{TObj}"/> instance.</returns>
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public static ComReleaser<TObj> Create<TObj>(TObj obj) where TObj : class => new ComReleaser<TObj>(obj);
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}
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/// <summary>
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/// A safe variable to hold an instance of a COM class that automatically calls <see cref="Marshal.ReleaseComObject(object)"/> on disposal.
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/// </summary>
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/// <typeparam name="T">The type of the COM object.</typeparam>
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/// <seealso cref="System.IDisposable"/>
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public class ComReleaser<T> : IDisposable where T : class
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{
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/// <summary>Initializes a new instance of the <see cref="ComReleaser{T}"/> class.</summary>
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/// <param name="obj">The COM object instance.</param>
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/// <exception cref="ArgumentNullException">obj</exception>
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/// <exception cref="ArgumentException">Argument value must be a COM object. - obj</exception>
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public ComReleaser(T obj)
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{
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if (obj == null) throw new ArgumentNullException(nameof(obj));
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if (!obj.GetType().IsCOMObject) throw new ArgumentException("Argument value must be a COM object.", nameof(obj));
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Item = obj;
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}
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/// <summary>Initializes a new instance of the <see cref="ComReleaser{T}"/> class.</summary>
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/// <param name="obj">The COM object instance.</param>
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/// <exception cref="ArgumentNullException">obj</exception>
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/// <exception cref="ArgumentException">Argument value must be a COM object and expose <typeparamref name="T"/>.</exception>
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public ComReleaser(object obj)
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{
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if (obj == null) throw new ArgumentNullException(nameof(obj));
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if (!obj.GetType().IsCOMObject) throw new ArgumentException("Argument value must be a COM object.", nameof(obj));
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Item = obj is T t ? t : throw new ArgumentException($"Object must expose the {typeof(T).Name} interface.");
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}
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/// <summary>Gets the COM object.</summary>
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/// <value>The COM object.</value>
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public T Item { get; private set; }
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/// <summary>Performs an implicit conversion from <typeparamref name="T"/> to <see cref="ComReleaser{T}"/>.</summary>
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/// <param name="obj">The COM object.</param>
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/// <returns>The result of the conversion.</returns>
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public static explicit operator ComReleaser<T>(T obj) => new ComReleaser<T>(obj);
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/// <summary>Performs an implicit conversion from <see cref="ComReleaser{T}"/> to <typeparamref name="T"/>.</summary>
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/// <param name="co">The <see cref="ComReleaser{T}"/> instance.</param>
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/// <returns>The result of the conversion.</returns>
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public static explicit operator T(ComReleaser<T> co) => co.Item;
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/// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
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public void Dispose()
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{
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if (Item == null) return;
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Marshal.ReleaseComObject(Item);
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Item = null;
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}
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}
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} |