[Peek][PreviewPane]Show Copy entry in right-click copy menu (#33845)

## Summary of the Pull Request
Fixes two bugs:
- Peek: Missing "Copy" menu-item for all WebView2 previewers.
- PreviewPane: Missing "Copy" menu-item for markdown files only.

## Detailed Description of the Pull Request / Additional comments
The issues are:
- Peek: 
- When not using Monaco (markdown, html) - the default WebView2 context
menu has been disabled. I have enabled it and then disabled ALL
menu-items other than "Copy" (such as "Back").
- When using Monaco + Release (other code files) - current code tries to
use the Monaco context menu, but it is somehow disabled at runtime. I
spent MANY hours trying to find out why but without success. It works
fine when I view the generated html + js files in a browser or in a
Debug build or in PreviewPane. But I couldn't find the root cause.
Trying to fix it by enabling the WebView2 context menu instead doesn't
work as for whatever reason, WebView2 doesn't generate a "Copy"
menu-item (it thinks there's no selected text when there is). So in this
case, the only thing I could get to work was generating context
menu-items via WebView2 callbacks that call JS functions. As a bonus,
this way of doing it also allows "Toggle text wrapping" to work.
- PreviewPane:
- Markdown - the default WebView2 context menu has been disabled. Like
for Peek, I have enabled it and then disabled ALL menu-items other than
"Copy" (such as "Back").
- Monaco (other code files) - this already just works fine, so I've left
it as is. I *could* make it work the same way as I've done for Peek for
consistency, but I've chosen to leave it as is since it works.
  

![image](https://github.com/user-attachments/assets/d758ada7-bb62-4f40-bef7-ad08ffb83786)

![image](https://github.com/user-attachments/assets/4e0baa7e-632f-412a-b2b1-b9f666277ca7)

src/common/FilePreviewCommon/Assets/Monaco/index.html

@@ -9,7 +9,7 @@
         // `theme` can be "vs" for light theme or "vs-dark" for dark theme
         // `lang` is the language of the file
         // `wrap` if the editor is wrapping or not
-        
+
         var theme = ("[[PT_THEME]]" == "dark") ? "vs-dark" : "vs";
         var lang = "[[PT_LANG]]";
         var wrap = ([[PT_WRAP]] == 1) ? true : false;
@@ -19,11 +19,29 @@
         var stickyScroll = ([[PT_STICKY_SCROLL]] == 1) ? true : false;
 
         var fontSize = [[PT_FONT_SIZE]];
-        
+        var contextMenu = ([[PT_CONTEXTMENU]] == 1) ? true : false;
+
+        var editor;
+
         // Code taken from https://stackoverflow.com/a/30106551/14774889
-        var code = decodeURIComponent(atob(base64code).split('').map(function(c) {
+        var code = decodeURIComponent(atob(base64code).split('').map(function (c) {
             return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);
         }).join(''));
+
+        function runToggleTextWrapCommand() {
+            if (wrap) {
+                editor.updateOptions({ wordWrap: 'off' })
+            } else {
+                editor.updateOptions({ wordWrap: 'on' })
+            }
+            wrap = !wrap;
+        }
+
+        function runCopyCommand() {
+            editor.focus();
+            document.execCommand('copy');
+        }
+
     </script>
     <!-- Set browser to Edge-->
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
@@ -33,32 +51,33 @@
     <title>Previewer for developer Files</title>
     <style>
         /* Fits content to window size */
-        html, body{
-            padding:0;
+        html, body {
+            padding: 0;
         }
-        #container,.monaco-editor {
-            position:fixed;
-            height:100%;
-            left:0;
-            top:0;
-            right:0;
-            bottom:0;
+
+        #container, .monaco-editor {
+            position: fixed;
+            height: 100%;
+            left: 0;
+            top: 0;
+            right: 0;
+            bottom: 0;
         }
-        .overflowingContentWidgets{
+
+        .overflowingContentWidgets {
             /*Hides alert box */
-            display:none!important
-        } 
+            display: none !important
+        }
     </style>
 </head>
 
-<body oncontextmenu="onContextMenu()">
+<body>
     <!-- Container for the editor -->
     <div id="container"></div>
     <!-- Script -->
     <script src="http://[[PT_URL]]/monacoSRC/min/vs/loader.js"></script>
     <script src="http://[[PT_URL]]/monacoSpecialLanguages.js" type="module"></script>
-<script type="module">
-        var editor;
+    <script type="module">
         import { registerAdditionalLanguages } from 'http://[[PT_URL]]/monacoSpecialLanguages.js';
         import { customTokenColors } from 'http://[[PT_URL]]/customTokenColors.js';
         require.config({ paths: { vs: 'http://[[PT_URL]]/monacoSRC/min/vs' } });
@@ -80,8 +99,9 @@
                 language: lang, // Sets language of the code
                 readOnly: true, // Sets to readonly
                 theme: 'theme', // Sets editor theme
-                minimap: {enabled: false}, // Disables minimap
+                minimap: { enabled: false }, // Disables minimap
                 lineNumbersMinChars: '3', // Width of the line numbers
+                contextmenu: contextMenu,
                 scrollbar: {
                     // Deactivate shadows
                     shadows: false,
@@ -90,7 +110,7 @@
                     vertical: 'auto',
                     horizontal: 'auto',
                 },
-                stickyScroll: {enabled: stickyScroll},
+                stickyScroll: { enabled: stickyScroll },
                 fontSize: fontSize,
                 wordWrap: (wrap ? 'on' : 'off') // Word wraps
             });
@@ -117,12 +137,7 @@
                 // Method that will be executed when the action is triggered.
                 // @param editor The editor instance is passed in as a convenience
                 run: function (ed) {
-                    if (wrap) {
-                        editor.updateOptions({ wordWrap: 'off' })
-                    } else {
-                        editor.updateOptions({ wordWrap: 'on' })
-                    }
-                    wrap = !wrap;
+                    runToggleTextWrapCommand();
                 }
             });
 
@@ -151,4 +166,4 @@
         }
     </script>
 </body>
-</html>
+</html>

src/modules/peek/Peek.FilePreviewer/Controls/BrowserControl.xaml.cs

@@ -3,20 +3,26 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
+using System.Windows.Controls;
 using ManagedCommon;
 using Microsoft.UI;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.Web.WebView2.Core;
 using Peek.Common.Constants;
+using Peek.Common.Helpers;
 using Windows.ApplicationModel.DataTransfer;
 using Windows.System;
 using Windows.UI;
 
+using Control = System.Windows.Controls.Control;
+
 namespace Peek.FilePreviewer.Controls
 {
-    public sealed partial class BrowserControl : UserControl, IDisposable
+    public sealed partial class BrowserControl : Microsoft.UI.Xaml.Controls.UserControl, IDisposable
     {
         /// <summary>
         /// Helper private Uri where we cache the last navigated page
@@ -67,6 +73,25 @@ namespace Peek.FilePreviewer.Controls
             }
         }
 
+        public static readonly DependencyProperty CustomContextMenuProperty = DependencyProperty.Register(
+            nameof(CustomContextMenu),
+            typeof(bool),
+            typeof(BrowserControl),
+            null);
+
+        public bool CustomContextMenu
+        {
+            get
+            {
+                return (bool)GetValue(CustomContextMenuProperty);
+            }
+
+            set
+            {
+                SetValue(CustomContextMenuProperty, value);
+            }
+        }
+
         public BrowserControl()
         {
             this.InitializeComponent();
@@ -78,6 +103,7 @@ namespace Peek.FilePreviewer.Controls
             if (PreviewBrowser.CoreWebView2 != null)
             {
                 PreviewBrowser.CoreWebView2.DOMContentLoaded -= CoreWebView2_DOMContentLoaded;
+                PreviewBrowser.CoreWebView2.ContextMenuRequested -= CoreWebView2_ContextMenuRequested;
             }
         }
 
@@ -145,7 +171,7 @@ namespace Peek.FilePreviewer.Controls
                 PreviewBrowser.DefaultBackgroundColor = Color.FromArgb(0, 0, 0, 0);
 
                 PreviewBrowser.CoreWebView2.Settings.AreDefaultScriptDialogsEnabled = false;
-                PreviewBrowser.CoreWebView2.Settings.AreDefaultContextMenusEnabled = false;
+                PreviewBrowser.CoreWebView2.Settings.AreDefaultContextMenusEnabled = true;
                 PreviewBrowser.CoreWebView2.Settings.AreDevToolsEnabled = false;
                 PreviewBrowser.CoreWebView2.Settings.AreHostObjectsAllowed = false;
                 PreviewBrowser.CoreWebView2.Settings.IsGeneralAutofillEnabled = false;
@@ -164,6 +190,7 @@ namespace Peek.FilePreviewer.Controls
 
                 PreviewBrowser.CoreWebView2.DOMContentLoaded += CoreWebView2_DOMContentLoaded;
                 PreviewBrowser.CoreWebView2.NewWindowRequested += CoreWebView2_NewWindowRequested;
+                PreviewBrowser.CoreWebView2.ContextMenuRequested += CoreWebView2_ContextMenuRequested;
             }
             catch (Exception ex)
             {
@@ -173,6 +200,87 @@ namespace Peek.FilePreviewer.Controls
             Navigate();
         }
 
+        private List<Control> GetContextMenuItems(CoreWebView2 sender, CoreWebView2ContextMenuRequestedEventArgs args)
+        {
+            var menuItems = args.MenuItems;
+
+            if (menuItems.IsReadOnly)
+            {
+                return [];
+            }
+
+            if (CustomContextMenu)
+            {
+                MenuItem CreateCommandMenuItem(string resourceId, string commandName)
+                {
+                    MenuItem commandMenuItem = new()
+                    {
+                        Header = ResourceLoaderInstance.ResourceLoader.GetString(resourceId),
+                        IsEnabled = true,
+                    };
+
+                    commandMenuItem.Click += async (s, ex) =>
+                    {
+                        await sender.ExecuteScriptAsync($"{commandName}()");
+                    };
+
+                    return commandMenuItem;
+                }
+
+                // When using Monaco, we show menu items that call the appropriate JS functions -
+                // WebView2 isn't able to show a "Copy" menu item of its own.
+                return [
+                           CreateCommandMenuItem("ContextMenu_Copy", "runCopyCommand"),
+                           new Separator(),
+                           CreateCommandMenuItem("ContextMenu_ToggleTextWrapping", "runToggleTextWrapCommand"),
+                       ];
+            }
+            else
+            {
+                MenuItem CreateMenuItemFromWebViewMenuItem(CoreWebView2ContextMenuItem webViewMenuItem)
+                {
+                    MenuItem menuItem = new()
+                    {
+                        Header = webViewMenuItem.Label.Replace('&', '_'),  // replace with '_' so it is underlined in the label
+                        IsEnabled = webViewMenuItem.IsEnabled,
+                        InputGestureText = webViewMenuItem.ShortcutKeyDescription,
+                    };
+
+                    menuItem.Click += (_, _) =>
+                    {
+                        args.SelectedCommandId = webViewMenuItem.CommandId;
+                    };
+
+                    return menuItem;
+                }
+
+                // When not using Monaco, we keep the "Copy" menu item from WebView2's default context menu.
+                return menuItems.Where(menuItem => menuItem.Name == "copy")
+                                .Select(CreateMenuItemFromWebViewMenuItem)
+                                .ToList<Control>();
+            }
+        }
+
+        private void CoreWebView2_ContextMenuRequested(CoreWebView2 sender, CoreWebView2ContextMenuRequestedEventArgs args)
+        {
+            var deferral = args.GetDeferral();
+            args.Handled = true;
+
+            var menuItems = GetContextMenuItems(sender, args);
+
+            if (menuItems.Count != 0)
+            {
+                var contextMenu = new ContextMenu();
+                contextMenu.Closed += (_, _) => deferral.Complete();
+                contextMenu.IsOpen = true;
+
+                foreach (var menuItem in menuItems)
+                {
+                    contextMenu.Items.Add(menuItem);
+                }
+            }
+        }
+
         private void CoreWebView2_DOMContentLoaded(CoreWebView2 sender, CoreWebView2DOMContentLoadedEventArgs args)
         {
             // If the file being previewed is HTML or HTM, reset the background color to its original state.
@@ -202,7 +310,7 @@ namespace Peek.FilePreviewer.Controls
             }
         }
 
-        private async void PreviewBrowser_NavigationStarting(WebView2 sender, Microsoft.Web.WebView2.Core.CoreWebView2NavigationStartingEventArgs args)
+        private async void PreviewBrowser_NavigationStarting(WebView2 sender, CoreWebView2NavigationStartingEventArgs args)
         {
             if (_navigatedUri == null)
             {
@@ -218,7 +326,7 @@ namespace Peek.FilePreviewer.Controls
             }
         }
 
-        private void PreviewWV2_NavigationCompleted(WebView2 sender, Microsoft.Web.WebView2.Core.CoreWebView2NavigationCompletedEventArgs args)
+        private void PreviewWV2_NavigationCompleted(WebView2 sender, CoreWebView2NavigationCompletedEventArgs args)
         {
             if (args.IsSuccess)
             {

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml

@@ -62,6 +62,7 @@
         <controls:BrowserControl
             x:Name="BrowserPreview"
             x:Load="True"
+            CustomContextMenu="{x:Bind BrowserPreviewer.CustomContextMenu, Mode=OneWay}"
             DOMContentLoaded="BrowserPreview_DOMContentLoaded"
             FlowDirection="LeftToRight"
             IsDevFilePreview="{x:Bind BrowserPreviewer.IsDevFilePreview, Mode=OneWay}"

src/modules/peek/Peek.FilePreviewer/Previewers/Interfaces/IBrowserPreviewer.cs

@@ -11,5 +11,7 @@ namespace Peek.FilePreviewer.Previewers.Interfaces
         public Uri? Preview { get; }
 
         public bool IsDevFilePreview { get; }
+
+        public bool CustomContextMenu { get; }
     }
 }

src/modules/peek/Peek.FilePreviewer/Previewers/WebBrowserPreviewer/Helpers/MonacoHelper.cs

@@ -80,6 +80,7 @@ namespace Peek.FilePreviewer.Previewers
 
             html = html.Replace("[[PT_LANG]]", vsCodeLangSet, StringComparison.InvariantCulture);
             html = html.Replace("[[PT_WRAP]]", wrapText ? "1" : "0", StringComparison.InvariantCulture);
+            html = html.Replace("[[PT_CONTEXTMENU]]", "0", StringComparison.InvariantCulture);
             html = html.Replace("[[PT_STICKY_SCROLL]]", stickyScroll ? "1" : "0", StringComparison.InvariantCulture);
             html = html.Replace("[[PT_THEME]]", theme, StringComparison.InvariantCulture);
             html = html.Replace("[[PT_FONT_SIZE]]", fontSize.ToString(CultureInfo.InvariantCulture), StringComparison.InvariantCulture);

src/modules/peek/Peek.FilePreviewer/Previewers/WebBrowserPreviewer/WebBrowserPreviewer.cs

@@ -43,6 +43,9 @@ namespace Peek.FilePreviewer.Previewers
         [ObservableProperty]
         private bool isDevFilePreview;
 
+        [ObservableProperty]
+        private bool customContextMenu;
+
         private bool disposed;
 
         public WebBrowserPreviewer(IFileSystemItem file, IPreviewSettings previewSettings)
@@ -107,9 +110,14 @@ namespace Peek.FilePreviewer.Previewers
                 {
                     bool isHtml = File.Extension == ".html" || File.Extension == ".htm";
                     bool isMarkdown = File.Extension == ".md";
-                    IsDevFilePreview = MonacoHelper.SupportedMonacoFileTypes.Contains(File.Extension);
 
-                    if (IsDevFilePreview && !isHtml && !isMarkdown)
+                    bool supportedByMonaco = MonacoHelper.SupportedMonacoFileTypes.Contains(File.Extension);
+                    bool useMonaco = supportedByMonaco && !isHtml && !isMarkdown;
+
+                    IsDevFilePreview = supportedByMonaco;
+                    CustomContextMenu = useMonaco;
+
+                    if (useMonaco)
                     {
                         var raw = await ReadHelper.Read(File.Path.ToString());
                         Preview = new Uri(MonacoHelper.PreviewTempFile(raw, File.Extension, TempFolderPath.Path, _previewSettings.SourceCodeTryFormat, _previewSettings.SourceCodeWrapText, _previewSettings.SourceCodeStickyScroll, _previewSettings.SourceCodeFontSize));

src/modules/peek/Peek.UI/Strings/en-us/Resources.resw

@@ -318,4 +318,12 @@
     <value>Length: {0}</value>
     <comment>{0} is the duration of the audio read from file metadata</comment>
   </data>
+  <data name="ContextMenu_Copy" xml:space="preserve">
+    <value>Copy</value>
+    <comment>Copy selected text to clipboard</comment>
+  </data>
+  <data name="ContextMenu_ToggleTextWrapping" xml:space="preserve">
+    <value>Toggle text wrapping</value>
+    <comment>Toggle whether text in pane is word-wrapped</comment>
+  </data>
 </root>

src/modules/previewpane/MarkdownPreviewHandler/MarkdownPreviewHandlerControl.cs

@@ -143,7 +143,7 @@ namespace Microsoft.PowerToys.PreviewHandler.Markdown
                         await _browser.EnsureCoreWebView2Async(_webView2Environment).ConfigureAwait(true);
                         _browser.CoreWebView2.SetVirtualHostNameToFolderMapping(VirtualHostName, AssemblyDirectory, CoreWebView2HostResourceAccessKind.Deny);
                         _browser.CoreWebView2.Settings.AreDefaultScriptDialogsEnabled = false;
-                        _browser.CoreWebView2.Settings.AreDefaultContextMenusEnabled = false;
+                        _browser.CoreWebView2.Settings.AreDefaultContextMenusEnabled = true;
                         _browser.CoreWebView2.Settings.AreDevToolsEnabled = false;
                         _browser.CoreWebView2.Settings.AreHostObjectsAllowed = false;
                         _browser.CoreWebView2.Settings.IsGeneralAutofillEnabled = false;
@@ -162,6 +162,23 @@ namespace Microsoft.PowerToys.PreviewHandler.Markdown
                             }
                         };
 
+                        _browser.CoreWebView2.ContextMenuRequested += (object sender, CoreWebView2ContextMenuRequestedEventArgs args) =>
+                        {
+                            var menuItems = args.MenuItems;
+
+                            if (!menuItems.IsReadOnly)
+                            {
+                                var copyMenuItem = menuItems.FirstOrDefault(menuItem => menuItem.Name == "copy");
+
+                                menuItems.Clear();
+
+                                if (copyMenuItem != null)
+                                {
+                                    menuItems.Add(copyMenuItem);
+                                }
+                            }
+                        };
+
                         // WebView2.NavigateToString() limitation
                         // See https://learn.microsoft.com/dotnet/api/microsoft.web.webview2.core.corewebview2.navigatetostring?view=webview2-dotnet-1.0.864.35#remarks
                         // While testing the limit, it turned out it is ~1.5MB, so to be on a safe side we go for 1.5m bytes

src/modules/previewpane/MonacoPreviewHandler/MonacoPreviewHandlerControl.cs

@@ -396,6 +396,7 @@ namespace Microsoft.PowerToys.PreviewHandler.Monaco
             _html = FilePreviewCommon.MonacoHelper.ReadIndexHtml();
             _html = _html.Replace("[[PT_LANG]]", _vsCodeLangSet, StringComparison.InvariantCulture);
             _html = _html.Replace("[[PT_WRAP]]", _settings.Wrap ? "1" : "0", StringComparison.InvariantCulture);
+            _html = _html.Replace("[[PT_CONTEXTMENU]]", "1", StringComparison.InvariantCulture);
             _html = _html.Replace("[[PT_THEME]]", Settings.GetTheme(), StringComparison.InvariantCulture);
             _html = _html.Replace("[[PT_STICKY_SCROLL]]", _settings.StickyScroll ? "1" : "0", StringComparison.InvariantCulture);
             _html = _html.Replace("[[PT_FONT_SIZE]]", _settings.FontSize.ToString(CultureInfo.InvariantCulture), StringComparison.InvariantCulture);