(C#)Windows Shell 外壳编程系列3 - 上下文菜单(iContextMenu)（一）右键菜单

（本系列文章由柠檬的(lc_mtt)原创，转载请注明出处，谢谢～）

这里解释上一节中获取名称的方法

GetDisplayNameOf 定义：

void GetDisplayNameOf(
            IntPtr pidl,
            SHGNO uFlags,
            IntPtr lpName);

该方法是用来转换PIDL成为可显示的名称字符串。PIDL必须是相对于对象的父目录的。换句话说，它必须包含一个非空的SHITEMID 结构。因为有多种命名对象的方式，资源管理器通过在uFlags参数中定义SHGNO标识的组合来表示名称类型。SHGDN_NORMAL或SHGDN_INFOLDER将被用来指定名称是相对于文件夹的还是相对于桌面的。其他三个值SHGDN_FOREDITING、SHGDN_FORADDRESSBAR和SHGDN_FORPARSING可以用来指定名称的用途。 名称必须按STRRET的结构形式返回，如果SHGDN_FOREDITING、SHGDN_FORADDRESSBAR和 SHGDN_FORPARSING没有设定，就返回外壳对象的显示名称。
具体实现方法：

/**//// <summary>
/// 获取显示名称
/// </summary>
public static string GetNameByIShell(IShellFolder Root, IntPtr pidlSub)
{
            IntPtr strr = Marshal.AllocCoTaskMem(MAX_PATH * 2 + 4);
            Marshal.WriteInt32(strr, 0, 0);
            StringBuilder buf = new StringBuilder(MAX_PATH);
            Root.GetDisplayNameOf(pidlSub, SHGNO.INFOLDER, strr);
            API.StrRetToBuf(strr, pidlSub, buf, MAX_PATH);
            Marshal.FreeCoTaskMem(strr);
return buf.ToString();
        }

SHGNO
public enum SHGNO
{
        NORMAL = 0x0,
        INFOLDER = 0x1,
        FOREDITING = 0x1000,
        FORADDRESSBAR = 0x4000,
        FORPARSING = 0x8000,
    }

事实上，只要修改 SHGNO ，就可以获取其绝对路径：

/**//// <summary>
/// 根据路径获取 IShellFolder 和 PIDL
/// </summary>
public static IShellFolder GetShellFolder(IShellFolder desktop, string path, out IntPtr Pidl)
{
            IShellFolder IFolder;
uint i, j = 0;
            desktop.ParseDisplayName(IntPtr.Zero, IntPtr.Zero, path, out i, out Pidl, ref j);
            desktop.BindToObject(Pidl, IntPtr.Zero, ref Guids.IID_IShellFolder, out IFolder);
return IFolder;
        }

但我们还关心类似“桌面”、“我的文档”这种既是普通文件夹又是特殊对象的绝对路径如何获得，这里就要用到 SHGetSpecialFolderPath API 了。

[DllImport("Shell32.Dll")]
private static extern bool SHGetSpecialFolderPath(
            IntPtr hwndOwner, 
            StringBuilder lpszPath,
            ShellSpecialFolders nFolder,
bool fCreate);

ShellSpecialFolders
public enum ShellSpecialFolders
{
        DESKTOP = 0x0000,         // <desktop>
        INTERNET = 0x0001,
        PROGRAMS = 0x0002,        // Start Menu\Programs
        CONTROLS = 0x0003,        // My Computer\Control Panel
        PRINTERS = 0x0004,        // My Computer\Printers
        PERSONAL = 0x0005,        // My Documents
        FAVORITES = 0x0006,        // <user name>\Favorites
        STARTUP = 0x0007,        // Start Menu\Programs\Startup
        RECENT = 0x0008,        // <user name>\Recent
        SENDTO = 0x0009,        // <user name>\SendTo
        BITBUCKET = 0x000a,        // <desktop>\Recycle Bin
        STARTMENU = 0x000b,        // <user name>\Start Menu
        MYDOCUMENTS = 0x000c,        // logical "My Documents" desktop icon
        MYMUSIC = 0x000d,        // "My Music" folder
        MYVIDEO = 0x000e,        // "My Videos" folder
        DESKTOPDIRECTORY = 0x0010,        // <user name>\Desktop
        DRIVES = 0x0011,        // My Computer
        NETWORK = 0x0012,        // Network Neighborhood (My Network Places)
        NETHOOD = 0x0013,        // <user name>\nethood
        FONTS = 0x0014,        // windows\fonts
        TEMPLATES = 0x0015,
        COMMON_STARTMENU = 0x0016,        // All Users\Start Menu
        COMMON_PROGRAMS = 0X0017,        // All Users\Start Menu\Programs
        COMMON_STARTUP = 0x0018,        // All Users\Startup
        COMMON_DESKTOPDIRECTORY = 0x0019,        // All Users\Desktop
        APPDATA = 0x001a,        // <user name>\Application Data
        PRINTHOOD = 0x001b,        // <user name>\PrintHood
        LOCAL_APPDATA = 0x001c,        // <user name>\Local Settings\Applicaiton Data (non roaming)
        ALTSTARTUP = 0x001d,        // non localized startup
        COMMON_ALTSTARTUP = 0x001e,        // non localized common startup
        COMMON_FAVORITES = 0x001f,
        INTERNET_CACHE = 0x0020,
        COOKIES = 0x0021,
        HISTORY = 0x0022,
        COMMON_APPDATA = 0x0023,        // All Users\Application Data
        WINDOWS = 0x0024,        // GetWindowsDirectory()
        SYSTEM = 0x0025,        // GetSystemDirectory()
        PROGRAM_FILES = 0x0026,        // C:\Program Files
        MYPICTURES = 0x0027,        // C:\Program Files\My Pictures
        PROFILE = 0x0028,        // USERPROFILE
        SYSTEMX86 = 0x0029,        // x86 system directory on RISC
        PROGRAM_FILESX86 = 0x002a,        // x86 C:\Program Files on RISC
        PROGRAM_FILES_COMMON = 0x002b,        // C:\Program Files\Common
        PROGRAM_FILES_COMMONX86 = 0x002c,        // x86 Program Files\Common on RISC
        COMMON_TEMPLATES = 0x002d,        // All Users\Templates
        COMMON_DOCUMENTS = 0x002e,        // All Users\Documents
        COMMON_ADMINTOOLS = 0x002f,        // All Users\Start Menu\Programs\Administrative Tools
        ADMINTOOLS = 0x0030,        // <user name>\Start Menu\Programs\Administrative Tools
        CONNECTIONS = 0x0031,        // Network and Dial-up Connections
        COMMON_MUSIC = 0x0035,        // All Users\My Music
        COMMON_PICTURES = 0x0036,        // All Users\My Pictures
        COMMON_VIDEO = 0x0037,        // All Users\My Video
        RESOURCES = 0x0038,        // Resource Direcotry
        RESOURCES_LOCALIZED = 0x0039,        // Localized Resource Direcotry
        COMMON_OLINKS = 0x003a,        // Links to All Users OEM specific apps
        CDBURN_AREA = 0x003b,        // USERPROFILE\Local Settings\Application Data\Microsoft\CD Burning
        COMPUTERSNEARME = 0x003d,        // Computers Near Me (computered from Workgroup membership)
        FLAG_CREATE = 0x8000,        // combine with  value to force folder creation in SHGetFolderPath()
        FLAG_DONT_VERIFY = 0x4000,        // combine with  value to return an unverified folder path
        FLAG_NO_ALIAS = 0x1000,        // combine with  value to insure non-alias versions of the pidl
        FLAG_PER_USER_INIT = 0x0800,        // combine with  value to indicate per-user init (eg. upgrade)
        FLAG_MASK = 0xFF00,        // mask for all possible flag values
    }

/**//// <summary>
/// 获取特殊文件夹的路径
/// </summary>
public static string GetSpecialFolderPath(IntPtr hwnd, ShellSpecialFolders nFolder)
{
            StringBuilder sb = new StringBuilder(MAX_PATH);
            SHGetSpecialFolderPath(hwnd, sb, nFolder, false);
return sb.ToString();
        }

上下文菜单
对象的上下文菜单相关的接口是IContextMenu，通过对象的父文件夹的IShellFolder.GetUIObjectOf方法可得到该接口。得到该接口后，可以用IContextMenu.QueryContextMenu方法来生成上下文菜单的菜单项，用IContextMenu.InvokeCommand调用相应的命令。
好，让我们一步一步来实现 IShellFolder 对象的上下文菜单弹出。
首先假设我们已经获得某个 IShellFolder 对象的 PIDL 和其上级 IShellFolder 对象：

IntPtr PIDL;
IShellFolder IParent;

然后我们定义一个存放 PIDL 的数组：

IntPtr[] pidls = new IntPtr[1];
pidls[0] = PIDL;

没错，我们的确要用到 PIDL 数组。可以理解，你在资源管理器中选择了多个文件/文件夹，再点击右键，弹出的上下文菜单将有所不同。你可以根据需要，把同一级的多个 PIDL 放到数组里面，实现这个效果。由于我们在例2的树中弹出菜单，所以只存放一个节点的 PIDL。
IContextMenu 是一个接口，我们这样定义：

IContextMenu.cs
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace WinShell
{
    [ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), GuidAttribute("000214e4-0000-0000-c000-000000000046")]
public interface IContextMenu
{
        [PreserveSig()]
        Int32 QueryContextMenu(
            IntPtr hmenu,
uint iMenu,
uint idCmdFirst,
uint idCmdLast,
            CMF uFlags);

        [PreserveSig()]
        Int32 InvokeCommand(
ref CMINVOKECOMMANDINFOEX info);

        [PreserveSig()]
void GetCommandString(
int idcmd,
            GetCommandStringInformations uflags,
int reserved,
            StringBuilder commandstring,
int cch);
    }
}

然后，通过 IParent 的 GetUIObjectOf 方法我们可以得到该节点的一个或多个指定子节点的 IContextMenu 接口：

GetUIObjectOf
IntPtr GetUIObjectOf(
            IntPtr hwndOwner,
uint cidl,
            [MarshalAs(UnmanagedType.LPArray)] IntPtr[] apidl,
            [In()] ref Guid riid,
out IntPtr rgfReserved);

//得到 IContextMenu 接口
                    IntPtr iContextMenuPtr = IntPtr.Zero;
                    iContextMenuPtr = IParent.GetUIObjectOf(IntPtr.Zero, (uint)pidls.Length, 
                        pidls, ref Guids.IID_IContextMenu, out iContextMenuPtr);
                    IContextMenu iContextMenu = (IContextMenu)Marshal.GetObjectForIUnknown(iContextMenuPtr);

得到 IContextMenu 后我们需要提供一个弹出式菜单的句柄，并把他传给 IContextMenu.QueryContextMenu，如果该方法执行成功的话，会在我们的菜单里加入相应的菜单项。

//提供一个弹出式菜单的句柄
IntPtr contextMenu = API.CreatePopupMenu();
iContextMenu.QueryContextMenu(contextMenu, 0,
API.CMD_FIRST, API.CMD_LAST, CMF.NORMAL | CMF.EXPLORE);

有了菜单项，我们就可以弹出该菜单了，我们用 TPM_RETURNCMD 标志指定 TrackPopupMenu 必须返回用户所选菜单项的 ID，以便稍后通过IContextMenu.InvokeCommand 来执行菜单命令：

//弹出菜单
uint cmd = API.TrackPopupMenuEx(contextMenu,TPM.RETURNCMD,
MousePosition.X, MousePosition.Y, this.Handle, IntPtr.Zero);

//获取命令序号，执行菜单命令
if (cmd >= API.CMD_FIRST)
{
    CMINVOKECOMMANDINFOEX invoke = new CMINVOKECOMMANDINFOEX();
    invoke.cbSize = Marshal.SizeOf(typeof(CMINVOKECOMMANDINFOEX));
    invoke.lpVerb = (IntPtr)(cmd - 1);
    invoke.lpDirectory = string.Empty;
    invoke.fMask = 0;
    invoke.ptInvoke = new POINT(MousePosition.X, MousePosition.Y);
    invoke.nShow = 1;
    iContextMenu.InvokeCommand(ref invoke);
}

惯例附上图片和源代码：

源代码：/Files/lemony/WinShell3.rar