Use stackalloc and ILFree

Author: 0x5bfa

src/Files.App/Services/Windows/WindowsWallpaperService.cs

@@ -18,32 +18,32 @@ public sealed class WindowsWallpaperService : IWindowsWallpaperService
 		public unsafe void SetDesktopWallpaper(string szPath)
 		{
 			using ComPtr<IDesktopWallpaper> pDesktopWallpaper = default;
+			var CLSID_DesktopWallpaper = typeof(DesktopWallpaper).GUID;
 			var IID_DesktopWallpaper = typeof(IDesktopWallpaper).GUID;
-			var CLSID_desktopWallpaper = typeof(DesktopWallpaper).GUID;
 
 			HRESULT hr = PInvoke.CoCreateInstance(
-				&CLSID_desktopWallpaper,
+				&CLSID_DesktopWallpaper,
 				null,
 				CLSCTX.CLSCTX_LOCAL_SERVER,
 				&IID_DesktopWallpaper,
 				(void**)pDesktopWallpaper.GetAddressOf())
 			.ThrowOnFailure();
 
-			// Get total count of all monitors available
-			hr = pDesktopWallpaper.Get()->GetMonitorDevicePathCount(out var dwMonitorCount)
-				.ThrowOnFailure();
+			// Get total count of all available monitors
+			hr = pDesktopWallpaper.Get()->GetMonitorDevicePathCount(out var dwMonitorCount).ThrowOnFailure();
 
 			fixed (char* pszPath = szPath)
 			{
-				PWSTR pMonitorID = default;
+				PWSTR pMonitorId = default;
 
-				// Set the selected image file as wallpaper to all monitors available
+				// Set the selected image file as wallpaper for all available monitors
 				for (uint dwIndex = 0u; dwIndex < dwMonitorCount; dwIndex++)
 				{
-					hr = pDesktopWallpaper.Get()->GetMonitorDevicePathAt(dwIndex, &pMonitorID).ThrowOnFailure();
-					hr = pDesktopWallpaper.Get()->SetWallpaper(pMonitorID, pszPath).ThrowOnFailure();
+					// Set the wallpaper
+					hr = pDesktopWallpaper.Get()->GetMonitorDevicePathAt(dwIndex, &pMonitorId).ThrowOnFailure();
+					hr = pDesktopWallpaper.Get()->SetWallpaper(pMonitorId, pszPath).ThrowOnFailure();
 
-					pMonitorID = default;
+					pMonitorId = default;
 				}
 			}
 		}
@@ -52,37 +52,37 @@ public unsafe void SetDesktopWallpaper(string szPath)
 		public unsafe void SetDesktopSlideshow(string[] aszPaths)
 		{
 			using ComPtr<IDesktopWallpaper> pDesktopWallpaper = default;
+			var CLSID_DesktopWallpaper = typeof(DesktopWallpaper).GUID;
 			var IID_DesktopWallpaper = typeof(IDesktopWallpaper).GUID;
-			var CLSID_desktopWallpaper = typeof(DesktopWallpaper).GUID;
 
 			HRESULT hr = PInvoke.CoCreateInstance(
-				&CLSID_desktopWallpaper,
+				&CLSID_DesktopWallpaper,
 				null,
 				CLSCTX.CLSCTX_LOCAL_SERVER,
 				&IID_DesktopWallpaper,
 				(void**)pDesktopWallpaper.GetAddressOf())
 			.ThrowOnFailure();
 
-			var dwCount = (uint)aszPaths.Length;
+			uint dwCount = (uint)aszPaths.Length;
+			ITEMIDLIST** ppItemIdList = stackalloc ITEMIDLIST*[dwCount];
 
-			fixed (ITEMIDLIST** ppItemIdList = new ITEMIDLIST*[dwCount])
-			{
-				for (uint dwIndex = 0u; dwIndex < dwCount; dwIndex++)
-				{
-					var id = PInvoke.ILCreateFromPath(aszPaths[dwIndex]);
-					ppItemIdList[dwIndex] = id;
-				}
+			// Get array of PIDL from the selected image files
+			for (uint dwIndex = 0u; dwIndex < dwCount; dwIndex++)
+				ppItemIdList[dwIndex] = PInvoke.ILCreateFromPath(aszPaths[dwIndex]);
 
-				// Get a shell array of the selected image files
-				using ComPtr<IShellItemArray> pShellItemArray = default;
-				PInvoke.SHCreateShellItemArrayFromIDLists(dwCount, ppItemIdList, pShellItemArray.GetAddressOf());
+			// Get a shell array of the array of the PIDL
+			using ComPtr<IShellItemArray> pShellItemArray = default;
+			hr = PInvoke.SHCreateShellItemArrayFromIDLists(dwCount, ppItemIdList, pShellItemArray.GetAddressOf()).ThrowOnFailure();
 
-				// Set the slideshow
-				hr = pDesktopWallpaper.Get()->SetSlideshow(pShellItemArray.Get());
-			}
+			// Set the slideshow
+			hr = pDesktopWallpaper.Get()->SetSlideshow(pShellItemArray.Get()).ThrowOnFailure();
+
+			// Free the allocated PIDL
+			for (uint dwIndex = 0u; dwIndex < dwCount; dwIndex++)
+				ILFree(ppItemIdList[dwIndex]);
 
 			// Set wallpaper position to fill the monitor.
-			hr = pDesktopWallpaper.Get()->SetPosition(DESKTOP_WALLPAPER_POSITION.DWPOS_FILL);
+			hr = pDesktopWallpaper.Get()->SetPosition(DESKTOP_WALLPAPER_POSITION.DWPOS_FILL).ThrowOnFailure();
 		}
 
 		/// <inheritdoc/>