WidgetProviderFactory.cs

// Copyright (C) Microsoft Corporation.
// Licensed under the MIT License.

using Microsoft.Windows.Widgets.Providers;
using System;
using System.Runtime.InteropServices;
using WinRT;

namespace WidgetHelper
{
  namespace Com
  {
    static class Guids
    {
      public const string IClassFactory = "00000001-0000-0000-C000-000000000046";
      public const string IUnknown = "00000000-0000-0000-C000-000000000046";
    }

    [ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid(Guids.IClassFactory)]
    internal interface IClassFactory
    {
      [PreserveSig]
      int CreateInstance(IntPtr pUnkOuter, ref Guid riid, out IntPtr ppvObject);
      [PreserveSig]
      int LockServer(bool fLock);
    }

    static class ClassObject
    {
      public static void Register(Guid clsid, object pUnk, out uint cookie)
      {
        [DllImport("ole32.dll")]
        static extern int CoRegisterClassObject(
            [MarshalAs(UnmanagedType.LPStruct)] Guid rclsid,
            [MarshalAs(UnmanagedType.IUnknown)] object pUnk,
            uint dwClsContext,
            uint flags,
            out uint lpdwRegister);

        int result = CoRegisterClassObject(clsid, pUnk, 0x4, 0x1, out cookie);
        if (result != 0)
        {
          Marshal.ThrowExceptionForHR(result);
        }
      }

      public static int Revoke(uint cookie)
      {
        [DllImport("ole32.dll")]
        static extern int CoRevokeClassObject(uint dwRegister);

        return CoRevokeClassObject(cookie);
      }
    }
  }

  internal class WidgetProviderFactory<T> : Com.IClassFactory
          where T : IWidgetProvider, new()
  {
    public int CreateInstance(IntPtr pUnkOuter, ref Guid riid, out IntPtr ppvObject)
    {
      ppvObject = IntPtr.Zero;

      if (pUnkOuter != IntPtr.Zero)
      {
        Marshal.ThrowExceptionForHR(CLASS_E_NOAGGREGATION);
      }

      if (riid == typeof(T).GUID || riid == Guid.Parse(Com.Guids.IUnknown))
      {
        // Create the instance of the .NET object
        ppvObject = MarshalInspectable<IWidgetProvider>.FromManaged(new T());
      }
      else
      {
        // The object that ppvObject points to does not support the
        // interface identified by riid.
        Marshal.ThrowExceptionForHR(E_NOINTERFACE);
      }

      return 0;
    }

    int Com.IClassFactory.LockServer(bool fLock)
    {
      return 0;
    }

    private const int CLASS_E_NOAGGREGATION = -2147221232;
    private const int E_NOINTERFACE = -2147467262;
  }
}