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234 lines (205 loc) · 9.48 KB
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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
}
}
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