Juknum.Windows.ContextMenu 0.0.4

Juknum.Windows.ContextMenu

A .NET library for building Windows Explorer context menu handlers with IExplorerCommand. This library is intended for .NET developers who want to add custom commands to the Windows Explorer context menu without having to implement the COM plumbing themselves.

Targets & Dependencies

The library depends on Vanara.PInvoke.Shell32 for the Explorer COM interfaces and shell types.

Overview

The library focuses on three pieces:

• Single commands through ExplorerCommand
• Submenu / grouped commands through ExplorerCommandMenu
• Registry registration helpers through RegistrationHelper

ExplorerCommand

Handles the COM-facing IExplorerCommand implementation and maps it to a simpler override-based API.

Example

[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
[Guid("...")]
internal class ContextMenuCommandHelloWorld : ExplorerCommand {
	public override Guid Guid => new("...");
	public override string Title => "Hello World";

	public override bool Execute(IShellItemArray psiItemArray, IBindCtx? pbc) {
		MessageBox.Show("Hello, World!");
		return true;
	}
}

ExplorerCommandMenu

Builds on top of ExplorerCommand, this class is useful when you want to create a submenu in the Explorer context menu. It exposes a Commands array and uses the internal command enumerator to surface child items to Explorer.

Example

[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
[Guid("...")]
internal class ContextMenuExample : ExplorerCommandMenu {

	public override Guid Guid => new("...");
	public override string Title => "Example Context Menu";
	public override IExplorerCommand[] Commands => [
		new ContextMenuCommandHelloWorld(),
	];
}

RegistrationHelper

A static helper class that writes the registry entries that Explorer uses to discover a command handler. It supports registration for:

• All files
• Directories
• Directory background
• Optional extension-specific verbs

Use RegistrationHelper.RegisterCommand(...) from your COM registration hook to create the Explorer registry entries for your command handler.

The helper takes a verb name, display label, and CLSID, plus optional scope flags:

• allFiles: true registers under *\shell
• allFolders: true registers under Directory\shell and Directory\Background\shell
• extension: ".txt" registers for a specific file type

UnregisterCommand(...) removes the same verb from the common locations.

[ComRegisterFunction]
public static void Register(Type type) {
	RegistrationHelper.RegisterCommand(
		verbName: "ExampleContextMenu",
		menuLabel: "Example Context Menu",
		clsid: type.GUID.ToString("B"),
		allFiles: true,
		allFolders: true
	);
}

Registering In Explorer

The sample projects register the built assembly from their build scripts, but the mechanism differs by target framework:

• .NET Framework uses RegAsm.exe to register the DLL and to remove it.
• .NET Core / .NET 8+ uses the generated .comhost.dll and registers it with regsvr32.exe instead.

If you want to mirror the examples, look at the build hooks in examples/net481/Scripts and examples/net10.0-windows/Scripts. Both registration paths require elevated permissions because they write to Explorer-related registry locations.

Example Project

The sample project in examples/ shows one concrete way to wire the library together.

Notes

• The runtime behavior is Windows-only because the API is built around Explorer COM interfaces.
• Icon should return a shell-compatible icon reference, such as an assembly resource path, e.g. @"C:\Path\To\MyAssembly.dll,-123". The -123 is the resource ID of the icon in the DLL. You can also reference a .ico file or other shell-supported icon formats on disk. If you return null, the command will not have an icon in the context menu.