Feature: Added support for previewing Office files

src/Files.App/Files.App.csproj

@@ -1,4 +1,4 @@
-<!--  Copyright (c) 2023 Files Community. Licensed under the MIT License. See the LICENSE.  -->
+<!--  Copyright (c) 2023 Files Community. Licensed under the MIT License. See the LICENSE.  -->
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
@@ -77,6 +77,7 @@
     <ItemGroup>
         <PackageReference Include="ByteSize" Version="2.1.1" />
         <PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.1" />
+        <PackageReference Include="DirectNCore" Version="1.13.2.1" />
         <PackageReference Include="DiscUtils.Udf" Version="0.16.13" />
         <PackageReference Include="FluentFTP" Version="43.0.1" />
         <PackageReference Include="ini-parser-netstandard" Version="2.5.2" />
@@ -97,6 +98,7 @@
         <PackageReference Include="CommunityToolkit.WinUI.UI.Behaviors" Version="7.1.2" />
         <PackageReference Include="CommunityToolkit.WinUI.UI.Controls" Version="7.1.2" />
         <PackageReference Include="Tulpep.ActiveDirectoryObjectPicker" Version="3.0.11" />
+        <PackageReference Include="Vanara.PInvoke.DwmApi" Version="3.4.15" />
         <PackageReference Include="Vanara.Windows.Extensions" Version="3.4.16" />
         <PackageReference Include="WinUIEx" Version="2.1.0" />
         <PackageReference Include="Vanara.PInvoke.Mpr" Version="3.4.16" />

src/Files.App/Helpers/Interop/InteropHelpers.cs

@@ -5,6 +5,8 @@
 using Microsoft.UI.Xaml;
 using System.Reflection;
 using System.Runtime.InteropServices;
+using Vanara.PInvoke;
+using static Vanara.PInvoke.User32;
 
 namespace Files.App.Helpers
 {
@@ -51,6 +53,20 @@ public static void ChangeCursor(this UIElement uiElement, InputCursor cursor)
 				new object[] { cursor }
 			);
 		}
+
+		[DllImport(Lib.User32, SetLastError = true, EntryPoint = "SetWindowLong")]
+		private static extern int SetWindowLongPtr32(HWND hWnd, WindowLongFlags nIndex, IntPtr dwNewLong);
+
+		[DllImport(Lib.User32, SetLastError = true, EntryPoint = "SetWindowLongPtr")]
+		private static extern IntPtr SetWindowLongPtr64(HWND hWnd, WindowLongFlags nIndex, IntPtr dwNewLong);
+
+		public static IntPtr SetWindowLong(HWND hWnd, WindowLongFlags nIndex, IntPtr dwNewLong)
+		{
+			if (IntPtr.Size == 4)
+				return SetWindowLongPtr32(hWnd, nIndex, dwNewLong);
+			else
+				return SetWindowLongPtr64(hWnd, nIndex, dwNewLong);
+		}
 	}
 
 	[ComImport]

src/Files.App/UserControls/FilePreviews/ShellPreview.xaml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<UserControl
+	x:Class="Files.App.UserControls.FilePreviews.ShellPreview"
+	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+	xmlns:local="using:Files.App.UserControls.FilePreviews"
+	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	Unloaded="PreviewHost_Unloaded"
+	mc:Ignorable="d">
+
+	<ContentPresenter
+		Name="contentPresenter"
+		Background="Transparent"
+		Loaded="PreviewHost_Loaded"
+		PointerEntered="PreviewHost_PointerEntered"
+		SizeChanged="PreviewHost_SizeChanged" />
+</UserControl>

src/Files.App/UserControls/FilePreviews/ShellPreview.xaml.cs

@@ -0,0 +1,64 @@
+using Files.App.ViewModels.Previews;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Vanara.PInvoke;
+using Windows.Foundation;
+
+namespace Files.App.UserControls.FilePreviews
+{
+	public sealed partial class ShellPreview : UserControl
+	{
+		private ShellPreviewViewModel ViewModel { get; set; }
+
+		public ShellPreview(ShellPreviewViewModel model)
+		{
+			ViewModel = model;
+			this.InitializeComponent();
+		}
+
+		private void PreviewHost_Loaded(object sender, RoutedEventArgs e)
+		{
+			ViewModel.LoadPreview(contentPresenter);
+			ViewModel.SizeChanged(GetPreviewSize());
+			if (XamlRoot.Content is FrameworkElement element)
+			{
+				element.SizeChanged += PreviewHost_SizeChanged;
+				element.PointerEntered += PreviewHost_PointerEntered;
+			}
+		}
+
+		private void PreviewHost_SizeChanged(object sender, SizeChangedEventArgs e)
+		{
+			ViewModel.SizeChanged(GetPreviewSize());
+		}
+
+		private RECT GetPreviewSize()
+		{
+			var source = contentPresenter.TransformToVisual(XamlRoot.Content);
+			var physicalSize = contentPresenter.RenderSize;
+			var physicalPos = source.TransformPoint(new Point(0, 0));
+			var scale = XamlRoot.RasterizationScale;
+			var result = new RECT();
+			result.Left = (int)(physicalPos.X * scale + 0.5);
+			result.Top = (int)(physicalPos.Y * scale + 0.5);
+			result.Width = (int)(physicalSize.Width * scale + 0.5);
+			result.Height = (int)(physicalSize.Height * scale + 0.5);
+			return result;
+		}
+
+		private void PreviewHost_Unloaded(object sender, RoutedEventArgs e)
+		{
+			if (XamlRoot.Content is FrameworkElement element)
+			{
+				element.SizeChanged -= PreviewHost_SizeChanged;
+				element.PointerEntered -= PreviewHost_PointerEntered;
+			}
+			ViewModel.UnloadPreview();
+		}
+
+		private void PreviewHost_PointerEntered(object sender, Microsoft.UI.Xaml.Input.PointerRoutedEventArgs e)
+		{
+			ViewModel.PointerEntered(sender == contentPresenter);
+		}
+	}
+}

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

@@ -0,0 +1,43 @@
+using System;
+using System.Runtime.InteropServices;
+using Vanara.PInvoke;
+
+namespace Files.App.Utils.Shell
+{
+	public static class ItemStreamHelper
+	{
+		[DllImport("shlwapi.dll", CallingConvention = CallingConvention.StdCall, PreserveSig = true, CharSet = CharSet.Unicode)]
+		static extern HRESULT SHCreateStreamOnFileEx(string pszFile, STGM grfMode, uint dwAttributes, uint fCreate, IntPtr pstmTemplate, out IntPtr ppstm);
+
+		[DllImport("shell32.dll", CallingConvention = CallingConvention.StdCall, PreserveSig = true, CharSet = CharSet.Unicode)]
+		static extern HRESULT SHCreateItemFromParsingName(string pszPath, IntPtr pbc, ref Guid riid, out IntPtr ppv);
+
+		static readonly Guid IShellItemIid = Guid.ParseExact("43826d1e-e718-42ee-bc55-a1e261c37bfe", "d");
+
+		public static IntPtr IShellItemFromPath(string path)
+		{
+			IntPtr psi;
+			Guid iid = IShellItemIid;
+			var hr = SHCreateItemFromParsingName(path, IntPtr.Zero, ref iid, out psi);
+			if ((int)hr < 0)
+				return IntPtr.Zero;
+			return psi;
+		}
+
+		public static IntPtr IStreamFromPath(string path)
+		{
+			IntPtr pstm;
+			var hr = SHCreateStreamOnFileEx(path,
+				STGM.STGM_READ | STGM.STGM_FAILIFTHERE | STGM.STGM_SHARE_DENY_NONE,
+				0, 0, IntPtr.Zero, out pstm);
+			if ((int)hr < 0)
+				return IntPtr.Zero;
+			return pstm;
+		}
+
+		public static void ReleaseObject(IntPtr obj)
+		{
+			Marshal.Release(obj);
+		}
+	}
+}