Update

Author: 0x5bfa

src/Files.App/Utils/Shell/PreviewHandler.cs

@@ -170,7 +170,9 @@ unsafe void SetupHandler(Guid clsid)
 				null,
 				CLSCTX.CLSCTX_LOCAL_SERVER,
 				ref iid,
-				out object previewHandlerObject);
+				out void* previewHandlerPtr);
+
+			object previewHandlerObject = *(IPreviewHandler*)previewHandlerPtr;
 
 			// See https://blogs.msdn.microsoft.com/adioltean/2005/06/24/when-cocreateinstance-returns-0x80080005-co_e_server_exec_failure/
 			// CO_E_SERVER_EXEC_FAILURE also tends to happen when debugging in Visual Studio.
@@ -182,7 +184,7 @@ unsafe void SetupHandler(Guid clsid)
 			if ((int)hr < 0)
 				throw new COMException(cannotCreate, (int)hr);
 
-			pPreviewHandler = new(&previewHandlerObject);
+			pPreviewHandler = new(previewHandlerPtr);
 			previewHandler = (IPreviewHandler)previewHandlerObject;
 			if (previewHandler == null)
 			{

src/Files.App/ViewModels/UserControls/Previews/ShellPreviewViewModel.cs

@@ -13,6 +13,7 @@
 using Windows.Win32.Graphics.Direct3D11;
 using Windows.Win32.Graphics.DirectComposition;
 using Windows.Win32.Graphics.Dwm;
+using Windows.Win32.Graphics.Dxgi;
 using Windows.Win32.UI.Shell;
 using Windows.Win32.UI.WindowsAndMessaging;
 using WinRT;
@@ -71,34 +72,17 @@ public void SizeChanged(RECT size)
 			if (hwnd != HWND.Null)
 				PInvoke.SetWindowPos(hwnd, (HWND)0, size.left, size.top, size.Width, size.Height, SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE);
 
-			if (currentHandler != null)
-				currentHandler.ResetBounds(new(0, 0, size.Width, size.Height));
+			currentHandler?.ResetBounds(new(0, 0, size.Width, size.Height));
 
 			if (outputLink is not null)
 				outputLink.PlacementVisual.Size = new(size.Width, size.Height);
 		}
 
 		private unsafe LRESULT WndProc(HWND hwnd, uint msg, WPARAM wParam, LPARAM lParam)
 		{
-			//if (msg == 0x0081 /*WM_NCCREATE*/)
-			//{
-			//	try
-			//	{
-			//		var cp = Marshal.PtrToStructure<CREATESTRUCTW>(lParam).lpCreateParams;
-			//		var pCreateParams = new nint(cp);
-			//		if (pCreateParams != nint.Zero && GCHandle.FromIntPtr(pCreateParams).Target is IWindowInit wnd)
-			//			return wnd.InitWndProcOnNCCreate(
-			//				hwnd,
-			//				msg,
-			//				Marshal.GetFunctionPointerForDelegate(wndProc ?? throw new NullReferenceException()),
-			//				lParam);
-			//	}
-			//	catch { }
-			//}
-			//else
 			if (msg == 0x0001 /*WM_CREATE*/)
 			{
-				var clsid = FindPreviewHandlerFor(Item.FileExtension, hwnd.DangerousGetHandle());
+				var clsid = FindPreviewHandlerFor(Item.FileExtension, hwnd);
 
 				isOfficePreview = new Guid?[]
 				{
@@ -139,10 +123,13 @@ public unsafe void LoadPreview(UIElement presenter)
 
 			fixed (char* pszClassName = szClassName)
 			{
+				var pWindProc = Marshal.GetFunctionPointerForDelegate(WndProc);
+				var pfnWndProc = (delegate* unmanaged[Stdcall]<HWND, uint, WPARAM, LPARAM, LRESULT>)pWindProc;
+
 				wCls = new WNDCLASSEXW
 				{
 					cbSize = (uint)Marshal.SizeOf(typeof(WNDCLASSEXW)),
-					lpfnWndProc = new(WndProc),
+					lpfnWndProc = pfnWndProc,
 					hInstance = hInst,
 					lpszClassName = pszClassName,
 					style = 0,
@@ -159,7 +146,7 @@ public unsafe void LoadPreview(UIElement presenter)
 				{
 					hwnd = PInvoke.CreateWindowEx(
 						WINDOW_EX_STYLE.WS_EX_LAYERED | WINDOW_EX_STYLE.WS_EX_COMPOSITED,
-						wCls.Value.lpszClassName,
+						pszClassName,
 						pszWindowName,
 						WINDOW_STYLE.WS_CHILD | WINDOW_STYLE.WS_CLIPSIBLINGS | WINDOW_STYLE.WS_VISIBLE,
 						0, 0, 0, 0,
@@ -213,7 +200,7 @@ private unsafe bool ChildWindowToXaml(nint parent, UIElement presenter)
 			IUnknown* pControlSurface = default;
 
 			pDCompositionDevice->CreateVisual(&pChildVisual);
-			pDCompositionDevice->CreateSurfaceFromHwnd(new(hwnd.DangerousGetHandle()), &pControlSurface);
+			pDCompositionDevice->CreateSurfaceFromHwnd(hwnd, &pControlSurface);
 			pChildVisual->SetContent(pControlSurface);
 			if (pChildVisual is null || pControlSurface is null)
 				return false;
@@ -251,8 +238,8 @@ private unsafe bool ChildWindowToXaml(nint parent, UIElement presenter)
 
 		public void UnloadPreview()
 		{
-			if (hwnd != HWND.NULL)
-				DestroyWindow(hwnd);
+			if (hwnd != HWND.Null)
+				PInvoke.DestroyWindow(hwnd);
 
 			//outputLink?.Dispose();
 			outputLink = null;