Vanara/PInvoke/User32/WinUser.Hook.cs

using System;
using System.Runtime.InteropServices;
using System.Text;
using Vanara.InteropServices;
using static Vanara.PInvoke.Kernel32;

// ReSharper disable FieldCanBeMadeReadOnly.Global
// ReSharper disable InconsistentNaming

namespace Vanara.PInvoke
{
	public static partial class User32
	{
		/// <summary>The delegate for a hook procedure set by SetWindowsHookEx.</summary>
		/// <param name="nCode">A hook code that the hook procedure uses to determine the action to perform. The value of the hook code depends on the type of the hook; each type has its own characteristic set of hook codes.</param>
		/// <param name="wParam">The value depends on the hook code, but typically contains information about a message that was sent or posted.</param>
		/// <param name="lParam">The value depends on the hook code, but typically contains information about a message that was sent or posted.</param>
		/// <returns>The value depends on the hook code.</returns>
		[PInvokeData("WinUser.h")]
		[UnmanagedFunctionPointer(CallingConvention.Winapi)]
		public delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);

		/// <summary>The type of hook procedure to be installed.</summary>
		[PInvokeData("WinUser.h", MSDNShortId = "ms644990")]
		public enum HookType
		{
			/// <summary>Installs a hook procedure that monitors messages generated as a result of an input event in a dialog box, message box, menu, or scroll bar. For more information, see the MessageProc hook procedure.</summary>
			WH_MSGFILTER = -1,
			/// <summary>Installs a hook procedure that records input messages posted to the system message queue. This hook is useful for recording macros. For more information, see the JournalRecordProc hook procedure.</summary>
			WH_JOURNALRECORD = 0,
			/// <summary>Installs a hook procedure that posts messages previously recorded by a WH_JOURNALRECORD hook procedure. For more information, see the JournalPlaybackProc hook procedure.</summary>
			WH_JOURNALPLAYBACK = 1,
			/// <summary>Installs a hook procedure that monitors keystroke messages. For more information, see the KeyboardProc hook procedure.</summary>
			WH_KEYBOARD = 2,
			/// <summary>Installs a hook procedure that monitors messages posted to a message queue. For more information, see the GetMsgProc hook procedure.</summary>
			WH_GETMESSAGE = 3,
			/// <summary>Installs a hook procedure that monitors messages before the system sends them to the destination window procedure. For more information, see the CallWndProc hook procedure.</summary>
			WH_CALLWNDPROC = 4,
			/// <summary>Installs a hook procedure that receives notifications useful to a CBT application. For more information, see the CBTProc hook procedure.</summary>
			WH_CBT = 5,
			/// <summary>Installs a hook procedure that monitors messages generated as a result of an input event in a dialog box, message box, menu, or scroll bar. The hook procedure monitors these messages for all applications in the same desktop as the calling thread. For more information, see the SysMsgProc hook procedure.</summary>
			WH_SYSMSGFILTER = 6,
			/// <summary>Installs a hook procedure that monitors mouse messages. For more information, see the MouseProc hook procedure.</summary>
			WH_MOUSE = 7,
			/// <summary></summary>
			WH_HARDWARE = 8,
			/// <summary>Installs a hook procedure useful for debugging other hook procedures. For more information, see the DebugProc hook procedure.</summary>
			WH_DEBUG = 9,
			/// <summary>Installs a hook procedure that receives notifications useful to shell applications. For more information, see the ShellProc hook procedure.</summary>
			WH_SHELL = 10,
			/// <summary>Installs a hook procedure that will be called when the application's foreground thread is about to become idle. This hook is useful for performing low priority tasks during idle time. For more information, see the ForegroundIdleProc hook procedure.</summary>
			WH_FOREGROUNDIDLE = 11,
			/// <summary>Installs a hook procedure that monitors messages after they have been processed by the destination window procedure. For more information, see the CallWndRetProc hook procedure.</summary>
			WH_CALLWNDPROCRET = 12,
			/// <summary>Installs a hook procedure that monitors low-level keyboard input events. For more information, see the LowLevelKeyboardProc hook procedure.</summary>
			WH_KEYBOARD_LL = 13,
			/// <summary>Installs a hook procedure that monitors low-level mouse input events. For more information, see the LowLevelMouseProc hook procedure.</summary>
			WH_MOUSE_LL = 14
		}

		/// <summary>
		/// <para>
		/// Passes the hook information to the next hook procedure in the current hook chain. A hook procedure can call this function either
		/// before or after processing the hook information.
		/// </para>
		/// </summary>
		/// <param name="hhk">
		/// <para>Type: <c>HHOOK</c></para>
		/// <para>This parameter is ignored.</para>
		/// </param>
		/// <param name="nCode">
		/// <para>Type: <c>int</c></para>
		/// <para>
		/// The hook code passed to the current hook procedure. The next hook procedure uses this code to determine how to process the hook information.
		/// </para>
		/// </param>
		/// <param name="wParam">
		/// <para>Type: <c>WPARAM</c></para>
		/// <para>
		/// The wParam value passed to the current hook procedure. The meaning of this parameter depends on the type of hook associated with
		/// the current hook chain.
		/// </para>
		/// </param>
		/// <param name="lParam">
		/// <para>Type: <c>LPARAM</c></para>
		/// <para>
		/// The lParam value passed to the current hook procedure. The meaning of this parameter depends on the type of hook associated with
		/// the current hook chain.
		/// </para>
		/// </param>
		/// <returns>
		/// <para>Type: <c>Type: <c>LRESULT</c></c></para>
		/// <para>
		/// This value is returned by the next hook procedure in the chain. The current hook procedure must also return this value. The
		/// meaning of the return value depends on the hook type. For more information, see the descriptions of the individual hook procedures.
		/// </para>
		/// </returns>
		/// <remarks>
		/// <para>Hook procedures are installed in chains for particular hook types. <c>CallNextHookEx</c> calls the next hook in the chain.</para>
		/// <para>
		/// Calling <c>CallNextHookEx</c> is optional, but it is highly recommended; otherwise, other applications that have installed hooks
		/// will not receive hook notifications and may behave incorrectly as a result. You should call <c>CallNextHookEx</c> unless you
		/// absolutely need to prevent the notification from being seen by other applications.
		/// </para>
		/// </remarks>
		// https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-callnexthookex
		// LRESULT CallNextHookEx( HHOOK hhk, int nCode, WPARAM wParam, LPARAM lParam );
		[DllImport(Lib.User32, SetLastError = false, ExactSpelling = true)]
		[PInvokeData("winuser.h", MSDNShortId = "callnexthookex")]
		public static extern IntPtr CallNextHookEx(SafeHookHandle hhk, int nCode, IntPtr wParam, IntPtr lParam);

		/// <summary>
		/// <para>
		/// Passes the specified message and hook code to the hook procedures associated with the WH_SYSMSGFILTER and WH_MSGFILTER hooks. A
		/// <c>WH_SYSMSGFILTER</c> or <c>WH_MSGFILTER</c> hook procedure is an application-defined callback function that examines and,
		/// optionally, modifies messages for a dialog box, message box, menu, or scroll bar.
		/// </para>
		/// </summary>
		/// <param name="lpMsg">
		/// <para>Type: <c>LPMSG</c></para>
		/// <para>A pointer to an MSG structure that contains the message to be passed to the hook procedures.</para>
		/// </param>
		/// <param name="nCode">
		/// <para>Type: <c>int</c></para>
		/// <para>
		/// An application-defined code used by the hook procedure to determine how to process the message. The code must not have the same
		/// value as system-defined hook codes (MSGF_ and HC_) associated with the WH_SYSMSGFILTER and <c>WH_MSGFILTER</c> hooks.
		/// </para>
		/// </param>
		/// <returns>
		/// <para>Type: <c>Type: <c>BOOL</c></c></para>
		/// <para>If the application should process the message further, the return value is zero.</para>
		/// <para>If the application should not process the message further, the return value is nonzero.</para>
		/// </returns>
		/// <remarks>
		/// <para>
		/// The system calls <c>CallMsgFilter</c> to enable applications to examine and control the flow of messages during internal
		/// processing of dialog boxes, message boxes, menus, and scroll bars, or when the user activates a different window by pressing the
		/// ALT+TAB key combination.
		/// </para>
		/// <para>Install this hook procedure by using the SetWindowsHookEx function.</para>
		/// <para>Examples</para>
		/// <para>For an example, see WH_MSGFILTER and WH_SYSMSGFILTER Hooks.</para>
		/// </remarks>
		// https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-callmsgfiltera
		// BOOL CallMsgFilterA( LPMSG lpMsg, int nCode );
		[DllImport(Lib.User32, SetLastError = false, CharSet = CharSet.Auto)]
		[PInvokeData("winuser.h", MSDNShortId = "callmsgfilter")]
		[return: MarshalAs(UnmanagedType.Bool)]
		public static extern bool CallMsgFilter(ref MSG lpMsg, int nCode);

		/// <summary>
		/// <para>
		/// Installs an application-defined hook procedure into a hook chain. You would install a hook procedure to monitor the system for
		/// certain types of events. These events are associated either with a specific thread or with all threads in the same desktop as the
		/// calling thread.
		/// </para>
		/// </summary>
		/// <param name="idHook">
		/// <para>Type: <c>int</c></para>
		/// <para>The type of hook procedure to be installed. This parameter can be one of the following values.</para>
		/// <list type="table">
		/// <listheader>
		/// <term>Value</term>
		/// <term>Meaning</term>
		/// </listheader>
		/// <item>
		/// <term>WH_CALLWNDPROC 4</term>
		/// <term>
		/// Installs a hook procedure that monitors messages before the system sends them to the destination window procedure. For more
		/// information, see the CallWndProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_CALLWNDPROCRET 12</term>
		/// <term>
		/// Installs a hook procedure that monitors messages after they have been processed by the destination window procedure. For more
		/// information, see the CallWndRetProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_CBT 5</term>
		/// <term>
		/// Installs a hook procedure that receives notifications useful to a CBT application. For more information, see the CBTProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_DEBUG 9</term>
		/// <term>Installs a hook procedure useful for debugging other hook procedures. For more information, see the DebugProc hook procedure.</term>
		/// </item>
		/// <item>
		/// <term>WH_FOREGROUNDIDLE 11</term>
		/// <term>
		/// Installs a hook procedure that will be called when the application's foreground thread is about to become idle. This hook is
		/// useful for performing low priority tasks during idle time. For more information, see the ForegroundIdleProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_GETMESSAGE 3</term>
		/// <term>
		/// Installs a hook procedure that monitors messages posted to a message queue. For more information, see the GetMsgProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_JOURNALPLAYBACK 1</term>
		/// <term>
		/// Installs a hook procedure that posts messages previously recorded by a WH_JOURNALRECORD hook procedure. For more information, see
		/// the JournalPlaybackProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_JOURNALRECORD 0</term>
		/// <term>
		/// Installs a hook procedure that records input messages posted to the system message queue. This hook is useful for recording
		/// macros. For more information, see the JournalRecordProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_KEYBOARD 2</term>
		/// <term>Installs a hook procedure that monitors keystroke messages. For more information, see the KeyboardProc hook procedure.</term>
		/// </item>
		/// <item>
		/// <term>WH_KEYBOARD_LL 13</term>
		/// <term>
		/// Installs a hook procedure that monitors low-level keyboard input events. For more information, see the LowLevelKeyboardProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_MOUSE 7</term>
		/// <term>Installs a hook procedure that monitors mouse messages. For more information, see the MouseProc hook procedure.</term>
		/// </item>
		/// <item>
		/// <term>WH_MOUSE_LL 14</term>
		/// <term>
		/// Installs a hook procedure that monitors low-level mouse input events. For more information, see the LowLevelMouseProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_MSGFILTER -1</term>
		/// <term>
		/// Installs a hook procedure that monitors messages generated as a result of an input event in a dialog box, message box, menu, or
		/// scroll bar. For more information, see the MessageProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_SHELL 10</term>
		/// <term>
		/// Installs a hook procedure that receives notifications useful to shell applications. For more information, see the ShellProc hook procedure.
		/// </term>
		/// </item>
		/// <item>
		/// <term>WH_SYSMSGFILTER 6</term>
		/// <term>
		/// Installs a hook procedure that monitors messages generated as a result of an input event in a dialog box, message box, menu, or
		/// scroll bar. The hook procedure monitors these messages for all applications in the same desktop as the calling thread. For more
		/// information, see the SysMsgProc hook procedure.
		/// </term>
		/// </item>
		/// </list>
		/// </param>
		/// <param name="lpfn">
		/// <para>Type: <c>HOOKPROC</c></para>
		/// <para>
		/// A pointer to the hook procedure. If the dwThreadId parameter is zero or specifies the identifier of a thread created by a
		/// different process, the lpfn parameter must point to a hook procedure in a DLL. Otherwise, lpfn can point to a hook procedure in
		/// the code associated with the current process.
		/// </para>
		/// </param>
		/// <param name="hmod">
		/// <para>Type: <c>HINSTANCE</c></para>
		/// <para>
		/// A handle to the DLL containing the hook procedure pointed to by the lpfn parameter. The hMod parameter must be set to <c>NULL</c>
		/// if the dwThreadId parameter specifies a thread created by the current process and if the hook procedure is within the code
		/// associated with the current process.
		/// </para>
		/// </param>
		/// <param name="dwThreadId">
		/// <para>Type: <c>DWORD</c></para>
		/// <para>
		/// The identifier of the thread with which the hook procedure is to be associated. For desktop apps, if this parameter is zero, the
		/// hook procedure is associated with all existing threads running in the same desktop as the calling thread. For Windows Store apps,
		/// see the Remarks section.
		/// </para>
		/// </param>
		/// <returns>
		/// <para>Type: <c>Type: <c>HHOOK</c></c></para>
		/// <para>If the function succeeds, the return value is the handle to the hook procedure.</para>
		/// <para>If the function fails, the return value is <c>NULL</c>. To get extended error information, call GetLastError.</para>
		/// </returns>
		/// <remarks>
		/// <para>
		/// <c>SetWindowsHookEx</c> can be used to inject a DLL into another process. A 32-bit DLL cannot be injected into a 64-bit process,
		/// and a 64-bit DLL cannot be injected into a 32-bit process. If an application requires the use of hooks in other processes, it is
		/// required that a 32-bit application call <c>SetWindowsHookEx</c> to inject a 32-bit DLL into 32-bit processes, and a 64-bit
		/// application call <c>SetWindowsHookEx</c> to inject a 64-bit DLL into 64-bit processes. The 32-bit and 64-bit DLLs must have
		/// different names.
		/// </para>
		/// <para>
		/// Because hooks run in the context of an application, they must match the "bitness" of the application. If a 32-bit application
		/// installs a global hook on 64-bit Windows, the 32-bit hook is injected into each 32-bit process (the usual security boundaries
		/// apply). In a 64-bit process, the threads are still marked as "hooked." However, because a 32-bit application must run the hook
		/// code, the system executes the hook in the hooking app's context; specifically, on the thread that called <c>SetWindowsHookEx</c>.
		/// This means that the hooking application must continue to pump messages or it might block the normal functioning of the 64-bit processes.
		/// </para>
		/// <para>
		/// If a 64-bit application installs a global hook on 64-bit Windows, the 64-bit hook is injected into each 64-bit process, while all
		/// 32-bit processes use a callback to the hooking application.
		/// </para>
		/// <para>
		/// To hook all applications on the desktop of a 64-bit Windows installation, install a 32-bit global hook and a 64-bit global hook,
		/// each from appropriate processes, and be sure to keep pumping messages in the hooking application to avoid blocking normal
		/// functioning. If you already have a 32-bit global hooking application and it doesn't need to run in each application's context,
		/// you may not need to create a 64-bit version.
		/// </para>
		/// <para>
		/// An error may occur if the hMod parameter is <c>NULL</c> and the dwThreadId parameter is zero or specifies the identifier of a
		/// thread created by another process.
		/// </para>
		/// <para>
		/// Calling the CallNextHookEx function to chain to the next hook procedure is optional, but it is highly recommended; otherwise,
		/// other applications that have installed hooks will not receive hook notifications and may behave incorrectly as a result. You
		/// should call <c>CallNextHookEx</c> unless you absolutely need to prevent the notification from being seen by other applications.
		/// </para>
		/// <para>
		/// Before terminating, an application must call the UnhookWindowsHookEx function to free system resources associated with the hook.
		/// </para>
		/// <para>
		/// The scope of a hook depends on the hook type. Some hooks can be set only with global scope; others can also be set for only a
		/// specific thread, as shown in the following table.
		/// </para>
		/// <list type="table">
		/// <listheader>
		/// <term>Hook</term>
		/// <term>Scope</term>
		/// </listheader>
		/// <item>
		/// <term>WH_CALLWNDPROC</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_CALLWNDPROCRET</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_CBT</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_DEBUG</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_FOREGROUNDIDLE</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_GETMESSAGE</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_JOURNALPLAYBACK</term>
		/// <term>Global only</term>
		/// </item>
		/// <item>
		/// <term>WH_JOURNALRECORD</term>
		/// <term>Global only</term>
		/// </item>
		/// <item>
		/// <term>WH_KEYBOARD</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_KEYBOARD_LL</term>
		/// <term>Global only</term>
		/// </item>
		/// <item>
		/// <term>WH_MOUSE</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_MOUSE_LL</term>
		/// <term>Global only</term>
		/// </item>
		/// <item>
		/// <term>WH_MSGFILTER</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_SHELL</term>
		/// <term>Thread or global</term>
		/// </item>
		/// <item>
		/// <term>WH_SYSMSGFILTER</term>
		/// <term>Global only</term>
		/// </item>
		/// </list>
		/// <para>
		/// For a specified hook type, thread hooks are called first, then global hooks. Be aware that the WH_MOUSE, WH_KEYBOARD,
		/// WH_JOURNAL*, WH_SHELL, and low-level hooks can be called on the thread that installed the hook rather than the thread processing
		/// the hook. For these hooks, it is possible that both the 32-bit and 64-bit hooks will be called if a 32-bit hook is ahead of a
		/// 64-bit hook in the hook chain.
		/// </para>
		/// <para>
		/// The global hooks are a shared resource, and installing one affects all applications in the same desktop as the calling thread.
		/// All global hook functions must be in libraries. Global hooks should be restricted to special-purpose applications or to use as a
		/// development aid during application debugging. Libraries that no longer need a hook should remove its hook procedure.
		/// </para>
		/// <para>
		/// <c>Windows Store app development</c> If dwThreadId is zero, then window hook DLLs are not loaded in-process for the Windows Store
		/// app processes and the Windows Runtime broker process unless they are installed by either UIAccess processes (accessibility
		/// tools). The notification is delivered on the installer's thread for these hooks:
		/// </para>
		/// <list type="bullet">
		/// <item>
		/// <term>WH_JOURNALPLAYBACK</term>
		/// </item>
		/// <item>
		/// <term>WH_JOURNALRECORD</term>
		/// </item>
		/// <item>
		/// <term>WH_KEYBOARD</term>
		/// </item>
		/// <item>
		/// <term>WH_KEYBOARD_LL</term>
		/// </item>
		/// <item>
		/// <term>WH_MOUSE</term>
		/// </item>
		/// <item>
		/// <term>WH_MOUSE_LL</term>
		/// </item>
		/// </list>
		/// <para>
		/// This behavior is similar to what happens when there is an architecture mismatch between the hook DLL and the target application
		/// process, for example, when the hook DLL is 32-bit and the application process 64-bit.
		/// </para>
		/// <para>Examples</para>
		/// <para>For an example, see Installing and Releasing Hook Procedures.</para>
		/// </remarks>
		// https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-setwindowshookexa
		// HHOOK SetWindowsHookExA( int idHook, HOOKPROC lpfn, HINSTANCE hmod, DWORD dwThreadId );
		[DllImport(Lib.User32, SetLastError = true, CharSet = CharSet.Auto)]
		[PInvokeData("winuser.h", MSDNShortId = "setwindowshookex")]
		public static extern SafeHookHandle SetWindowsHookEx(HookType idHook, HookProc lpfn, HINSTANCE hMod, int dwThreadId);

		/// <summary>
		/// <para>Removes a hook procedure installed in a hook chain by the SetWindowsHookEx function.</para>
		/// </summary>
		/// <param name="hhk">
		/// <para>Type: <c>HHOOK</c></para>
		/// <para>A handle to the hook to be removed. This parameter is a hook handle obtained by a previous call to SetWindowsHookEx.</para>
		/// </param>
		/// <returns>
		/// <para>Type: <c>Type: <c>BOOL</c></c></para>
		/// <para>If the function succeeds, the return value is nonzero.</para>
		/// <para>If the function fails, the return value is zero. To get extended error information, call GetLastError.</para>
		/// </returns>
		/// <remarks>
		/// <para>
		/// The hook procedure can be in the state of being called by another thread even after <c>UnhookWindowsHookEx</c> returns. If the
		/// hook procedure is not being called concurrently, the hook procedure is removed immediately before <c>UnhookWindowsHookEx</c> returns.
		/// </para>
		/// <para>Examples</para>
		/// <para>For an example, see Monitoring System Events.</para>
		/// </remarks>
		// https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-unhookwindowshookex
		// BOOL UnhookWindowsHookEx( HHOOK hhk );
		[DllImport(Lib.User32, SetLastError = true, ExactSpelling = true)]
		[PInvokeData("winuser.h", MSDNShortId = "unhookwindowshookex")]
		[return: MarshalAs(UnmanagedType.Bool)]
		public static extern bool UnhookWindowsHookEx(IntPtr hhk);

		public class SafeHookHandle : GenericSafeHandle
		{
			public SafeHookHandle() : this(IntPtr.Zero) { }
			
			public SafeHookHandle(IntPtr handle, bool own = true) : base(handle, UnhookWindowsHookEx, own) { }
		}
	}
}