Update

Author: 0x5bfa

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

@@ -16,6 +16,10 @@ namespace Files.App.Utils.Shell
 	/// </summary>
 	public sealed class PreviewHandler : IDisposable
 	{
+		// Fields
+
+		private static readonly Guid IPreviewHandlerIid = Guid.ParseExact("8895b1c6-b41f-4c1c-a562-0d564250836f", "d");
+
 		#region IPreviewHandlerFrame support
 
 		[StructLayout(LayoutKind.Sequential)]
@@ -125,13 +129,16 @@ interface IObjectWithSite
 		IPreviewHandlerVisuals visuals;
 		nint pPreviewHandler;
 
+		// Initializer
+
 		public PreviewHandler(Guid clsid, nint frame)
 		{
 			disposed = true;
 			init = false;
 			shown = false;
 			comSite = new PreviewHandlerFrame(frame);
 			hwnd = frame;
+
 			try
 			{
 				SetupHandler(clsid);
@@ -151,7 +158,7 @@ public PreviewHandler(Guid clsid, nint frame)
 			}
 		}
 
-		static readonly Guid IPreviewHandlerIid = Guid.ParseExact("8895b1c6-b41f-4c1c-a562-0d564250836f", "d");
+		// Methods
 
 		unsafe void SetupHandler(Guid clsid)
 		{

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

@@ -24,17 +24,23 @@ namespace Files.App.ViewModels.Previews
 {
 	public sealed class ShellPreviewViewModel : BasePreviewModel
 	{
-		PreviewHandler? currentHandler;
-		ContentExternalOutputLink? outputLink;
+		// Fields
+
+		PreviewHandler? _currentPreviewHandler;
+		ContentExternalOutputLink? _contentExternalOutputLink;
 		WNDCLASSEXW _windowClass;
-		WNDPROC _windProc = default;
-		HWND hwnd = HWND.Null;
-		bool isOfficePreview = false;
+		WNDPROC _windProc = null!;
+		HWND _hWnd = HWND.Null;
+		bool _isOfficePreview = false;
+
+		// Initializer
 
 		public ShellPreviewViewModel(ListedItem item) : base(item)
 		{
 		}
 
+		// Methods
+
 		public async override Task<List<FileProperty>> LoadPreviewAndDetailsAsync()
 			=> [];
 
@@ -70,13 +76,13 @@ public async override Task<List<FileProperty>> LoadPreviewAndDetailsAsync()
 
 		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 (_hWnd != HWND.Null)
+				PInvoke.SetWindowPos(_hWnd, (HWND)0, size.left, size.top, size.Width, size.Height, SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE);
 
-			currentHandler?.ResetBounds(new(0, 0, size.Width, size.Height));
+			_currentPreviewHandler?.ResetBounds(new(0, 0, size.Width, size.Height));
 
-			if (outputLink is not null)
-				outputLink.PlacementVisual.Size = new(size.Width, size.Height);
+			if (_contentExternalOutputLink is not null)
+				_contentExternalOutputLink.PlacementVisual.Size = new(size.Width, size.Height);
 		}
 
 		private unsafe LRESULT WndProc(HWND hwnd, uint msg, WPARAM wParam, LPARAM lParam)
@@ -85,7 +91,7 @@ private unsafe LRESULT WndProc(HWND hwnd, uint msg, WPARAM wParam, LPARAM lParam
 			{
 				var clsid = FindPreviewHandlerFor(Item.FileExtension, hwnd);
 
-				isOfficePreview = new Guid?[]
+				_isOfficePreview = new Guid?[]
 				{
 					Guid.Parse("84F66100-FF7C-4fb4-B0C0-02CD7FB668FE"), // preview handler for Word files
 					Guid.Parse("65235197-874B-4A07-BDC5-E65EA825B718"), // preview handler for PowerPoint files
@@ -94,9 +100,9 @@ private unsafe LRESULT WndProc(HWND hwnd, uint msg, WPARAM wParam, LPARAM lParam
 
 				try
 				{
-					currentHandler = new PreviewHandler(clsid.Value, hwnd.Value);
-					currentHandler.InitWithFileWithEveryWay(Item.ItemPath);
-					currentHandler.DoPreview();
+					_currentPreviewHandler = new PreviewHandler(clsid.Value, hwnd.Value);
+					_currentPreviewHandler.InitWithFileWithEveryWay(Item.ItemPath);
+					_currentPreviewHandler.DoPreview();
 				}
 				catch
 				{
@@ -105,10 +111,10 @@ private unsafe LRESULT WndProc(HWND hwnd, uint msg, WPARAM wParam, LPARAM lParam
 			}
 			else if (msg == 0x0002 /*WM_DESTROY*/)
 			{
-				if (currentHandler is not null)
+				if (_currentPreviewHandler is not null)
 				{
-					currentHandler.UnloadPreview();
-					currentHandler = null;
+					_currentPreviewHandler.UnloadPreview();
+					_currentPreviewHandler = null;
 				}
 			}
 
@@ -148,7 +154,7 @@ public unsafe void LoadPreview(UIElement presenter)
 
 				fixed (char* pszWindowName = szWindowName)
 				{
-					hwnd = PInvoke.CreateWindowEx(
+					_hWnd = PInvoke.CreateWindowEx(
 						WINDOW_EX_STYLE.WS_EX_LAYERED | WINDOW_EX_STYLE.WS_EX_COMPOSITED,
 						pszClassName,
 						pszWindowName,
@@ -204,20 +210,20 @@ private unsafe bool ChildWindowToXaml(nint parent, UIElement presenter)
 			IUnknown* pControlSurface = default;
 
 			pDCompositionDevice->CreateVisual(&pChildVisual);
-			pDCompositionDevice->CreateSurfaceFromHwnd(hwnd, &pControlSurface);
+			pDCompositionDevice->CreateSurfaceFromHwnd(_hWnd, &pControlSurface);
 			pChildVisual->SetContent(pControlSurface);
 			if (pChildVisual is null || pControlSurface is null)
 				return false;
 
 			var compositor = ElementCompositionPreview.GetElementVisual(presenter).Compositor;
-			outputLink = ContentExternalOutputLink.Create(compositor);
+			_contentExternalOutputLink = ContentExternalOutputLink.Create(compositor);
 
-			var target = outputLink.As<IDCompositionTarget.Interface>();
+			var target = _contentExternalOutputLink.As<IDCompositionTarget.Interface>();
 			target.SetRoot(pChildVisual);
 
-			outputLink.PlacementVisual.Size = new(0, 0);
-			outputLink.PlacementVisual.Scale = new(1/(float)presenter.XamlRoot.RasterizationScale);
-			ElementCompositionPreview.SetElementChildVisual(presenter, outputLink.PlacementVisual);
+			_contentExternalOutputLink.PlacementVisual.Size = new(0, 0);
+			_contentExternalOutputLink.PlacementVisual.Scale = new(1/(float)presenter.XamlRoot.RasterizationScale);
+			ElementCompositionPreview.SetElementChildVisual(presenter, _contentExternalOutputLink.PlacementVisual);
 
 			pDCompositionDevice->Commit();
 
@@ -233,55 +239,57 @@ private unsafe bool ChildWindowToXaml(nint parent, UIElement presenter)
 
 			return
 				PInvoke.DwmSetWindowAttribute(
-					new((nint)hwnd),
+					new((nint)_hWnd),
 					DWMWINDOWATTRIBUTE.DWMWA_CLOAK,
 					&dwAttrib,
 					(uint)Marshal.SizeOf(dwAttrib))
 				.Succeeded;
 		}
 
-		public void UnloadPreview()
-		{
-			if (hwnd != HWND.Null)
-				PInvoke.DestroyWindow(hwnd);
-
-			//outputLink?.Dispose();
-			outputLink = null;
-
-			PInvoke.UnregisterClass(_windowClass.lpszClassName, PInvoke.GetModuleHandle(default(PWSTR)));
-		}
-
 		public unsafe void PointerEntered(bool onPreview)
 		{
 			if (onPreview)
 			{
 				var dwAttrib = Convert.ToUInt32(false);
 
 				PInvoke.DwmSetWindowAttribute(
-					new((nint)hwnd),
+					new((nint)_hWnd),
 					DWMWINDOWATTRIBUTE.DWMWA_CLOAK,
 					&dwAttrib,
 					(uint)Marshal.SizeOf(dwAttrib));
 
-				if (isOfficePreview)
-					PInvoke.SetWindowLong(hwnd, WINDOW_LONG_PTR_INDEX.GWL_EXSTYLE, 0);
+				if (_isOfficePreview)
+					PInvoke.SetWindowLong(_hWnd, WINDOW_LONG_PTR_INDEX.GWL_EXSTYLE, 0);
 			}
 			else
 			{
 				PInvoke.SetWindowLong(
-					hwnd,
+					_hWnd,
 					WINDOW_LONG_PTR_INDEX.GWL_EXSTYLE,
 					(int)(WINDOW_EX_STYLE.WS_EX_LAYERED | WINDOW_EX_STYLE.WS_EX_COMPOSITED));
 
 				var dwAttrib = Convert.ToUInt32(true);
 
 				PInvoke.DwmSetWindowAttribute(
-					new((nint)hwnd),
+					new((nint)_hWnd),
 					DWMWINDOWATTRIBUTE.DWMWA_CLOAK,
 					&dwAttrib,
 					(uint)Marshal.SizeOf(dwAttrib));
 			}
 		}
+
+		// Disposer
+
+		public void UnloadPreview()
+		{
+			if (_hWnd != HWND.Null)
+				PInvoke.DestroyWindow(_hWnd);
+
+			//outputLink?.Dispose();
+			_contentExternalOutputLink = null;
+
+			PInvoke.UnregisterClass(_windowClass.lpszClassName, PInvoke.GetModuleHandle(default(PWSTR)));
+		}
 	}
 }