OneScript/src/OneScript.Core/Rcw/DispatchUtility.cs at develop · dmpas/OneScript · GitHub

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/*----------------------------------------------------------

This Source Code Form is subject to the terms of the

Mozilla Public License, v.2.0. If a copy of the MPL

was not distributed with this file, You can obtain one

at http://mozilla.org/MPL/2.0/.

----------------------------------------------------------*/

// This code is based on

// https://www.codeproject.com/Articles/523417/Reflection-with-IDispatch-based-COM-objects

#region Using Directives

using System;

using System.Reflection;

using System.Runtime.InteropServices;

using System.Runtime.InteropServices.ComTypes;

using System.Security.Permissions;

#endregion

namespace OneScript.Rcw

{

/// <summary>

/// Provides helper methods for working with COM IDispatch objects that have a registered type library.

/// </summary>

public static class DispatchUtility

{

#region Private Constants

private const int S_OK = 0; //From WinError.h

private const int LOCALE_SYSTEM_DEFAULT = 2 << 10; //From WinNT.h == 2048 == 0x800

#endregion

#region Public Methods

/// <summary>

/// Gets whether the specified object implements IDispatch.

/// </summary>

/// <param name="obj">An object to check.</param>

/// <returns>True if the object implements IDispatch. False otherwise.</returns>

public static bool ImplementsIDispatch(object obj)

{

bool result = obj is IDispatchInfo;

return result;

}

public static int GetTypeInfoCount(object obj)

{

var dispatch = (IDispatchInfo) obj;

var hr = dispatch.GetTypeInfoCount(out var typeInfoCount);

return hr == S_OK ? typeInfoCount : 0;

}

/// <summary>

/// Gets a Type that can be used with reflection.

/// </summary>

/// <param name="obj">An object that implements IDispatch.</param>

/// <returns>A .NET Type that can be used with reflection.</returns>

/// <exception cref="InvalidCastException">If <paramref name="obj"/> doesn't implement IDispatch.</exception>

[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]

public static ITypeInfo GetITypeInfo(object obj)

{

RequireReference(obj, "obj");

var dispatch = (IDispatchInfo) obj;

dispatch.GetTypeInfo(0, LOCALE_SYSTEM_DEFAULT, out var typeInfo);

return typeInfo;

}

/// <summary>

/// Tries to get the DISPID for the requested member name.

/// </summary>

/// <param name="obj">An object that implements IDispatch.</param>

/// <param name="name">The name of a member to lookup.</param>

/// <param name="dispId">If the method returns true, this holds the DISPID on output.

/// If the method returns false, this value should be ignored.</param>

/// <returns>True if the member was found and resolved to a DISPID. False otherwise.</returns>

/// <exception cref="InvalidCastException">If <paramref name="obj"/> doesn't implement IDispatch.</exception>

[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]

public static bool TryGetDispId(object obj, string name, out int dispId)

{

RequireReference(obj, "obj");

bool result = TryGetDispId((IDispatchInfo)obj, name, out dispId);

return result;

}

/// <summary>

/// Invokes a member by DISPID.

/// </summary>

/// <param name="obj">An object that implements IDispatch.</param>

/// <param name="dispId">The DISPID of a member. This can be obtained using

/// <see cref="TryGetDispId(object, string, out int)"/>.</param>

/// <param name="args">The arguments to pass to the member.</param>

/// <returns>The member's return value.</returns>

/// <remarks>

/// This can invoke a method or a property get accessor.

/// </remarks>

public static object Invoke(object obj, int dispId, object[] args)

{

object result = Invoke(obj, dispId, args, null);

return result;

}

/// <summary>

/// Invokes a member by DISPID.

/// </summary>

/// <param name="obj">An object that implements IDispatch.</param>

/// <param name="dispId">The DISPID of a member. This can be obtained using

/// <see cref="TryGetDispId(object, string, out int)"/>.</param>

/// <param name="args">The arguments to pass to the member.</param>

/// <param name="modifiers">ByRef modifiers</param>

/// <returns>The member's return value.</returns>

/// <remarks>

/// This can invoke a method or a property get accessor.

/// </remarks>

public static object Invoke(object obj, int dispId, object[] args, ParameterModifier[] modifiers)

{

string memberName = "[DispId=" + dispId + "]";

object result = Invoke(obj, memberName, args, modifiers);

return result;

}

/// <summary>

/// Invokes a member by name.

/// </summary>

/// <param name="obj">An object.</param>

/// <param name="memberName">The name of the member to invoke.</param>

/// <param name="args">The arguments to pass to the member.</param>

/// <returns>The member's return value.</returns>

/// <remarks>

/// This can invoke a method or a property get accessor.

/// </remarks>

public static object Invoke(object obj, string memberName, object[] args, ParameterModifier[] modifiers)

{

RequireReference(obj, "obj");

Type type = obj.GetType();

object result = type.InvokeMember(memberName, BindingFlags.InvokeMethod | BindingFlags.GetProperty,

null, obj, args, modifiers, null, null);

return result;

}

/// <summary>

/// Invokes property setter by DispID

/// </summary>

/// <param name="obj">An object.</param>

/// <param name="dispId">The DISPID of a member. This can be obtained using

/// <see cref="TryGetDispId(object, string, out int)"/>.</param>

/// <param name="propValue">new value of the property</param>

public static void InvokeSetProperty(object obj, int dispId, object propValue)

{

string memberName = "[DispId=" + dispId + "]";

InvokeSetProperty(obj, memberName, propValue);

}

/// <summary>

/// Invokes property setter

/// </summary>

/// <param name="obj">An object.</param>

/// <param name="memberName">The name of the member to invoke.</param>

/// <param name="propValue">new value of the property</param>

public static void InvokeSetProperty(object obj, string memberName, object propValue)

{

RequireReference(obj, "obj");

Type type = obj.GetType();

object result = type.InvokeMember(memberName, BindingFlags.SetProperty,

null, obj, new object[]{propValue}, null);

}

#endregion

#region Private Methods

/// <summary>

/// Requires that the value is non-null.

/// </summary>

/// <typeparam name="T">The type of the value.</typeparam>

/// <param name="value">The value to check.</param>

/// <param name="name">The name of the value.</param>

private static void RequireReference<T>(T value, string name) where T : class

{

if (value == null)

{

throw new ArgumentNullException(name);

}

/// <summary>

/// Tries to get the DISPID for the requested member name.

/// </summary>

/// <param name="dispatch">An object that implements IDispatch.</param>

/// <param name="name">The name of a member to lookup.</param>

/// <param name="dispId">If the method returns true, this holds the DISPID on output.

/// If the method returns false, this value should be ignored.</param>

/// <returns>True if the member was found and resolved to a DISPID. False otherwise.</returns>

private static bool TryGetDispId(IDispatchInfo dispatch, string name, out int dispId)

{

RequireReference(dispatch, "dispatch");

RequireReference(name, "name");

bool result = false;

// Members names aren't usually culture-aware for IDispatch, so we might as well

// pass the default locale instead of looking up the current thread's LCID each time

// (via CultureInfo.CurrentCulture.LCID).

Guid iidNull = Guid.Empty;

int hr = dispatch.GetDispId(ref iidNull, ref name, 1, LOCALE_SYSTEM_DEFAULT, out dispId);

const int DISP_E_UNKNOWNNAME = unchecked((int)0x80020006); //From WinError.h

const int DISPID_UNKNOWN = -1; //From OAIdl.idl

if (hr == S_OK)

{

result = true;

}

else if (hr == DISP_E_UNKNOWNNAME && dispId == DISPID_UNKNOWN)

{

// This is the only supported "error" case because it means IDispatch

// is saying it doesn't know the member we asked about.

result = false;

}

else

{

// The other documented result codes are all errors.

Marshal.ThrowExceptionForHR(hr);

}

return result;

}

#endregion

}

OneScript/src/OneScript.Core/Rcw/DispatchUtility.cs at develop · dmpas/OneScript · GitHub

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