(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
