ComAwareEventInfo.cs

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using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using System.Runtime.Versioning;
 
namespace System.Runtime.InteropServices;
 
public class ComAwareEventInfo : EventInfo
{
    private readonly EventInfo _innerEventInfo;
 
    public override EventAttributes Attributes => _innerEventInfo.Attributes;
 
    public override Type? DeclaringType => _innerEventInfo.DeclaringType;
 
    public override int MetadataToken => _innerEventInfo.MetadataToken;
 
    public override Module Module => _innerEventInfo.Module;
 
    public override string Name => _innerEventInfo.Name;
 
    public override Type? ReflectedType => _innerEventInfo.ReflectedType;
 
    public ComAwareEventInfo([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicEvents)] Type type, string eventName)
    {
        _innerEventInfo = type.GetEvent(eventName);
    }
 
    [SupportedOSPlatform("windows")]
    public override void AddEventHandler(object target, Delegate handler)
    {
        if (Marshal.IsComObject(target))
        {
            GetDataForComInvocation(_innerEventInfo, out var sourceIid, out var dispid);
            ComEventsHelper.Combine(target, sourceIid, dispid, handler);
        }
        else
        {
            _innerEventInfo.AddEventHandler(target, handler);
        }
    }
 
    [SupportedOSPlatform("windows")]
    public override void RemoveEventHandler(object target, Delegate handler)
    {
        if (Marshal.IsComObject(target))
        {
            GetDataForComInvocation(_innerEventInfo, out var sourceIid, out var dispid);
            ComEventsHelper.Remove(target, sourceIid, dispid, handler);
        }
        else
        {
            _innerEventInfo.RemoveEventHandler(target, handler);
        }
    }
 
    public override MethodInfo? GetAddMethod(bool nonPublic)
    {
        return _innerEventInfo.GetAddMethod(nonPublic);
    }
 
    public override MethodInfo[] GetOtherMethods(bool nonPublic)
    {
        return _innerEventInfo.GetOtherMethods(nonPublic);
    }
 
    public override MethodInfo? GetRaiseMethod(bool nonPublic)
    {
        return _innerEventInfo.GetRaiseMethod(nonPublic);
    }
 
    public override MethodInfo? GetRemoveMethod(bool nonPublic)
    {
        return _innerEventInfo.GetRemoveMethod(nonPublic);
    }
 
    public override object[] GetCustomAttributes(Type attributeType, bool inherit)
    {
        return _innerEventInfo.GetCustomAttributes(attributeType, inherit);
    }
 
    public override object[] GetCustomAttributes(bool inherit)
    {
        return _innerEventInfo.GetCustomAttributes(inherit);
    }
 
    public override IList<CustomAttributeData> GetCustomAttributesData()
    {
        return _innerEventInfo.GetCustomAttributesData();
    }
 
    public override bool IsDefined(Type attributeType, bool inherit)
    {
        return _innerEventInfo.IsDefined(attributeType, inherit);
    }
 
    private static void GetDataForComInvocation(EventInfo eventInfo, out Guid sourceIid, out int dispid)
    {
        object[] customAttributes = eventInfo.DeclaringType.GetCustomAttributes(typeof(ComEventInterfaceAttribute), inherit: false);
        if (customAttributes == null || customAttributes.Length == 0)
        {
            throw new InvalidOperationException(System.SR.InvalidOperation_NoComEventInterfaceAttribute);
        }
        if (customAttributes.Length > 1)
        {
            throw new AmbiguousMatchException(System.SR.AmbiguousMatch_MultipleEventInterfaceAttributes);
        }
        Type sourceInterface = ((ComEventInterfaceAttribute)customAttributes[0]).SourceInterface;
        Guid gUID = sourceInterface.GUID;
        MethodInfo method = sourceInterface.GetMethod(eventInfo.Name);
        Attribute customAttribute = Attribute.GetCustomAttribute(method, typeof(DispIdAttribute));
        if (customAttribute == null)
        {
            throw new InvalidOperationException(System.SR.InvalidOperation_NoDispIdAttribute);
        }
        sourceIid = gUID;
        dispid = ((DispIdAttribute)customAttribute).Value;
    }
}