Merge pull request #4599 from MicrosoftEdge/api-specs-com-conversion

API Review: Interop between COM and WinRT

Author: david-risney

specs/CoreWebView2.CreateFromCOMObject.md

@@ -17,8 +17,14 @@ To help implement this for Unity, we are adding a new static factory function on
 class that will allow it to wrap an existing ICoreWebView2 COM object, instead of creating a new
 one.
 
+To round out the more general scenario of interoperating between libraries written in different
+languages, we add the ability to convert a CoreWebView2 to and from .NET and COM, as well as
+to and from WinRT and COM.
+
 # Examples
-## CoreWebView2.CreateFromComICoreWebView2
+
+## COM to .NET
+
 ```c#
 public class MyWebView2Control
 {
@@ -47,8 +53,52 @@ public class MyWebView2Control
 }
 ```
 
+## WinRT to COM
+
+```c++
+winrt::com_ptr<ICoreWebView2> GetComICoreWebView2FromCoreWebView2(
+    winrt::Microsoft::Web::WebView2::Core::CoreWebView2 coreWebView2WinRT)
+{
+    // Get the COM interop interface from the WinRT CoreWebView2.
+    auto interop = coreWebView2WinRT.as<ICoreWebView2Interop2>();
+
+    // Get the COM ICoreWebView2 object from the COM interop interface.
+    winrt::com_ptr<ICoreWebView2> coreWebView2Com;
+    winrt::check_hresult(interop->GetComICoreWebView2(coreWebView2Com.put()));
+	
+	return coreWebView2Com;
+}
+```
+
+## COM to WinRT
+
+```c++
+winrt::Microsoft::Web::WebView2::Core::CoreWebView2 CreateCoreWebView2FromComICoreWebView2(
+    winrt::com_ptr<ICoreWebView2> coreWebView2Com)
+{
+    auto factory = winrt::get_activation_factory<
+        winrt::Microsoft::Web::WebView2::Core::CoreWebView2>();
+	
+    // Get the COM interop interface from the WinRT factory.
+    auto interop = factory.try_as<ICoreWebView2ActivationFactoryInterop>();
+
+    // Get the WinRT CoreWebView2 object from the COM interop interface as
+    // its ABI interface.
+    winrt::com_ptr<IUnknown> coreWebView2WinRTAsIUnknown;
+    winrt::check_hresult(interop->CreateFromComICoreWebView2(
+        coreWebView2Com.get(), coreWebView2WinRTAsIUnknown.put()));
+
+    // Convert from the WinRT CoreWebView2 object API interface to C++/WinRT type
+    return coreWebView2WinRTAsIUnknown.as<
+        winrt::Microsoft::Web::WebView2::Core::CoreWebView2>();
+}
+```
+
 
 # API Details
+
+## .NET API
+
 ```c#
 namespace Microsoft.Web.WebView2.Core
 {
@@ -64,10 +114,48 @@ namespace Microsoft.Web.WebView2.Core
     /// <exception cref="ArgumentNullException">Thrown when the provided COM pointer is null.</exception>
     /// <exception cref="InvalidComObjectException">Thrown when the value is not an ICoreWebView2 COM object and cannot be wrapped.</exception>
     public static CoreWebView2 CreateFromComICoreWebView2(IntPtr value);
+
+    /// <summary>
+    /// Returns the existing COM ICoreWebView2 object underlying this .NET CoreWebView2 object.
+    /// This allows interacting with the WebView2 control using COM APIs,
+    /// even if the control was originally created using .NET.
+    /// </summary>
+    /// <returns>Pointer to a COM object that implements the ICoreWebView2 COM interface.</returns>
+    public IntPtr GetComICoreWebView2();
   }
 }
 ```
 
+## WinRT COM Interop API
+
+```c# (but really COM IDL)
+/// Interop interface for the CoreWebView2 WinRT object to allow WinRT end
+/// developers to be able to use COM interfaces as parameters for some methods.
+/// This interface is implemented by the Microsoft.Web.WebView2.Core.CoreWebView2
+/// runtime class.
+[uuid(B151AD7C-CFB0-4ECF-B9B2-AFCA868581A6), object, pointer_default(unique)]
+interface ICoreWebView2Interop2 : IUnknown {
+  /// Get a COM ICoreWebView2 interface corresponding to this WinRT CoreWebView2
+  /// object.
+  HRESULT GetComICoreWebView2([out, retval] ICoreWebView2** coreWebView2);
+}
+
+/// Interop interface for the CoreWebView2 WinRT activation factory object to allow
+/// WinRT end developers to be able to use COM interfaces as parameters for some
+/// methods.
+/// This interface is implemented by the Microsoft.Web.WebView2.Core.CoreWebView2
+/// activation factory runtime class.
+[uuid(BABBED43-D40E-40CF-B106-8ED65FAE2E7C), object, pointer_default(unique)]
+interface ICoreWebView2ActivationFactoryInterop : IUnknown {
+  /// Creates a CoreWebView2 WinRT object that wraps an existing COM ICoreWebView2 object.
+  /// This allows interacting with the WebView2 control using WinRT,
+  /// even if the control was originally created using COM.
+  HRESULT CreateFromComICoreWebView2([in] ICoreWebView2* coreWebView2Com,
+                                     [out, retval] IUnknown** coreWebView2WinRt);
+}
+
+```
+
 # Appendix
 We have a couple of other options to accomplish this, including moving the "CreateFromComICoreWebView2" function to the
 CoreWebView2Controller class instead. CoreWebView2Controller could then be used to get the CoreWebView2 through