ModernShareHelper.cs

// ModernShareHelper.cs — Public API for showing the Windows 10+ modern Share dialog. SBNET-1858
// This file is compiled only when targeting net6.0-windows10.0.17763.0 or later.
// Consumers can call ModernShareHelper.ShowShareUI() from a BeforeCommandExecute event
// to handle the "Windows.ModernShare" context menu verb.

#if WINDOWS10_0_17763_0_OR_GREATER

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Windows.ApplicationModel.DataTransfer;
using Windows.Storage;

namespace Jam.Shell
{
    /// <summary>
    /// COM interface for IDataTransferManagerInterop, used to show the modern share dialog
    /// from Win32 desktop applications. SBNET-1858
    /// </summary>
    [ComImport]
    [Guid("3A3DCD6C-3EAB-43DC-BCDE-45671CE800C8")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IDataTransferManagerInterop
    {
        [PreserveSig]
        int GetForWindow(
            IntPtr appWindow,
            ref Guid riid,
            out IntPtr dataTransferManager);

        [PreserveSig]
        int ShowShareUIForWindow(IntPtr appWindow);
    }

    /// <summary>
    /// Provides the Windows 10+ modern Share dialog for Win32 desktop applications.
    /// Use this class to handle the <c>Windows.ModernShare</c> context menu verb,
    /// which fails via plain <c>IContextMenu::InvokeCommand</c> from desktop apps.
    /// </summary>
    /// <remarks>
    /// This class is only available when targeting <c>net6.0-windows10.0.17763.0</c> or later.
    /// </remarks>
    /// <example>
    /// Handling the Share verb in a <see cref="ShellContextMenuProvider.BeforeCommandExecute"/> event:
    /// <code>
    /// shellBrowser.BeforeShellCommand += (sender, e) =>
    /// {
    ///     if (e.Verb.Verb == "Windows.ModernShare")
    ///     {
    ///         e.Cancel = true;
    ///         ModernShareHelper.ShowShareUI(this.Handle, e.Paths.ToList());
    ///     }
    /// };
    /// </code>
    /// </example>
    public static class ModernShareHelper
    {
        private static readonly Guid s_DataTransferManagerIid =
            new Guid("A5CAEE9B-8708-49D1-8D36-67D25A8DA00C");

        /// <summary>
        /// Determines whether the given verb string is the modern share verb.
        /// </summary>
        /// <param name="verb">The context menu verb to check.</param>
        /// <returns><c>true</c> if the verb is <c>Windows.ModernShare</c>; <c>false</c> otherwise.</returns>
        public static bool IsModernShareVerb(string verb)
        {
            return string.Equals(verb, "Windows.ModernShare", StringComparison.OrdinalIgnoreCase);
        }

        /// <summary>
        /// Shows the Windows 10+ modern Share dialog for the given window handle,
        /// sharing the specified file system paths.
        /// </summary>
        /// <param name="hwnd">The window handle to associate the share dialog with.</param>
        /// <param name="filePaths">The file system paths to share.</param>
        /// <returns><c>true</c> if the share dialog was shown successfully; <c>false</c> otherwise.</returns>
        public static bool ShowShareUI(IntPtr hwnd, IReadOnlyList<string> filePaths)
        {
            if (filePaths == null || filePaths.Count == 0)
                return false;

            try
            {
                // Get the IDataTransferManagerInterop COM interface from the activation factory.
                var interop = DataTransferManager.As<IDataTransferManagerInterop>();

                // Get the DataTransferManager for this window via raw COM.
                Guid dtmIid = s_DataTransferManagerIid;
                int hr = interop.GetForWindow(hwnd, ref dtmIid, out IntPtr dtmPtr);
                if (hr < 0 || dtmPtr == IntPtr.Zero)
                    return false;

                var dataTransferManager = DataTransferManager.FromAbi(dtmPtr);
                Marshal.Release(dtmPtr);

                // Subscribe to DataRequested to provide files when the share UI asks for them.
                dataTransferManager.DataRequested += (sender, args) =>
                {
                    var request = args.Request;
                    var data = request.Data;
                    data.Properties.Title = "Share";

                    var storageItems = new List<IStorageItem>();
                    foreach (string path in filePaths)
                    {
                        try
                        {
                            if (System.IO.Directory.Exists(path))
                            {
                                var folder = StorageFolder
                                    .GetFolderFromPathAsync(path)
                                    .AsTask().GetAwaiter().GetResult();
                                storageItems.Add(folder);
                            }
                            else if (System.IO.File.Exists(path))
                            {
                                var file = StorageFile
                                    .GetFileFromPathAsync(path)
                                    .AsTask().GetAwaiter().GetResult();
                                storageItems.Add(file);
                            }
                        }
                        catch (Exception ex)
                        {
                            Debug.WriteLine(
                                "ModernShareHelper: Could not add item '" + path + "': " + ex.Message);
                        }
                    }

                    if (storageItems.Count > 0)
                    {
                        data.SetStorageItems(storageItems);
                    }
                    else
                    {
                        request.FailWithDisplayText("No shareable files found.");
                    }
                };

                // Now show the share UI.
                hr = interop.ShowShareUIForWindow(hwnd);
                return hr >= 0;
            }
            catch (Exception ex)
            {
                Debug.WriteLine("ModernShareHelper.ShowShareUI failed: " + ex.Message);
                return false;
            }
        }

        /// <summary>
        /// Shows the Windows 10+ modern Share dialog for the given window handle,
        /// sharing the specified file system paths.
        /// </summary>
        /// <param name="hwnd">The window handle to associate the share dialog with.</param>
        /// <param name="filePaths">The file system paths to share.</param>
        /// <returns><c>true</c> if the share dialog was shown successfully; <c>false</c> otherwise.</returns>
        public static bool ShowShareUI(IntPtr hwnd, params string[] filePaths)
        {
            return ShowShareUI(hwnd, (IReadOnlyList<string>)filePaths);
        }
    }
}

#endif