382 lines
13 KiB
C#
382 lines
13 KiB
C#
/// KEYBOARD.CS
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/// (c) 2006 by Emma Burrows
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/// This file contains the following items:
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/// - KeyboardHook: class to enable low-level keyboard hook using
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/// the Windows API.
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/// - KeyboardHookEventHandler: delegate to handle the KeyIntercepted
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/// event raised by the KeyboardHook class.
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/// - KeyboardHookEventArgs: EventArgs class to contain the information
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/// returned by the KeyIntercepted event.
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///
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/// Change history:
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/// 17/06/06: 1.0 - First version.
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/// 18/06/06: 1.1 - Modified proc assignment in constructor to make class backward
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/// compatible with 2003.
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/// 10/07/06: 1.2 - Added support for modifier keys:
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/// -Changed filter in HookCallback to WM_KEYUP instead of WM_KEYDOWN
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/// -Imported GetKeyState from user32.dll
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/// -Moved native DLL imports to a separate internal class as this
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/// is a Good Idea according to Microsoft's guidelines
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/// 13/02/07: 1.3 - Improved modifier key support:
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/// -Added CheckModifiers() method
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/// -Deleted LoWord/HiWord methods as they weren't necessary
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/// -Implemented Barry Dorman's suggestion to AND GetKeyState
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/// values with 0x8000 to get their result
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/// 23/03/07: 1.4 - Fixed bug which made the Alt key appear stuck
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/// - Changed the line
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/// if (nCode >= 0 && (wParam == (IntPtr)WM_KEYUP || wParam == (IntPtr)WM_SYSKEYUP))
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/// to
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/// if (nCode >= 0)
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/// {
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/// if (wParam == (IntPtr)WM_KEYUP || wParam == (IntPtr)WM_SYSKEYUP)
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/// ...
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/// Many thanks to "Scottie Numbnuts" for the solution.
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using System;
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using System.Diagnostics;
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using System.Windows.Forms;
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using System.Runtime.InteropServices;
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using System.Text;
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/// <summary>
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/// Low-level keyboard intercept class to trap and suppress system keys.
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/// </summary>
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namespace USB_Lockdown
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{
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internal class KeyboardLock // ##Made by me! (Needs testing)
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{
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private static KeyboardHook KH;
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internal static void enable()
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{
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KH = new KeyboardHook();
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}
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internal static void disable()
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{
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KH.Dispose();
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KH = null;
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}
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}
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public class KeyboardHook : IDisposable
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{
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/// <summary>
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/// Parameters accepted by the KeyboardHook constructor.
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/// </summary>
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public enum Parameters
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{
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None,
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AllowAltTab,
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AllowWindowsKey,
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AllowAltTabAndWindows,
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PassAllKeysToNextApp
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}
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//Internal parameters
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private bool PassAllKeysToNextApp = false;
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private bool AllowAltTab = false;
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private bool AllowWindowsKey = false;
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//Keyboard API constants
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private const int WH_KEYBOARD_LL = 13;
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private const int WM_KEYUP = 0x0101;
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private const int WM_SYSKEYUP = 0x0105;
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//Modifier key constants
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private const int VK_SHIFT = 0x10;
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private const int VK_CONTROL = 0x11;
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private const int VK_MENU = 0x12;
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private const int VK_CAPITAL = 0x14;
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//Variables used in the call to SetWindowsHookEx
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private HookHandlerDelegate proc;
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private IntPtr hookID = IntPtr.Zero;
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internal delegate IntPtr HookHandlerDelegate(
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int nCode, IntPtr wParam, ref KBDLLHOOKSTRUCT lParam);
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/// <summary>
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/// Event triggered when a keystroke is intercepted by the
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/// low-level hook.
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/// </summary>
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public event KeyboardHookEventHandler KeyIntercepted;
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// Structure returned by the hook whenever a key is pressed
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internal struct KBDLLHOOKSTRUCT
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{
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public int vkCode;
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int scanCode;
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public int flags;
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int time;
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int dwExtraInfo;
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}
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#region Constructors
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/// <summary>
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/// Sets up a keyboard hook to trap all keystrokes without
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/// passing any to other applications.
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/// </summary>
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public KeyboardHook()
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{
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proc = new HookHandlerDelegate(HookCallback);
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using (Process curProcess = Process.GetCurrentProcess())
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using (ProcessModule curModule = curProcess.MainModule)
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{
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hookID = NativeMethods.SetWindowsHookEx(WH_KEYBOARD_LL, proc,
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NativeMethods.GetModuleHandle(curModule.ModuleName), 0);
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}
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}
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/// <summary>
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/// Sets up a keyboard hook with custom parameters.
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/// </summary>
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/// <param name="param">A valid name from the Parameter enum; otherwise, the
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/// default parameter Parameter.None will be used.</param>
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public KeyboardHook(string param)
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: this()
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{
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if (!String.IsNullOrEmpty(param) && Enum.IsDefined(typeof(Parameters), param))
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{
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SetParameters((Parameters)Enum.Parse(typeof(Parameters), param));
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}
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}
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/// <summary>
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/// Sets up a keyboard hook with custom parameters.
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/// </summary>
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/// <param name="param">A value from the Parameters enum.</param>
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public KeyboardHook(Parameters param)
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: this()
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{
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SetParameters(param);
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}
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private void SetParameters(Parameters param)
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{
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switch (param)
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{
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case Parameters.None:
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break;
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case Parameters.AllowAltTab:
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AllowAltTab = true;
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break;
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case Parameters.AllowWindowsKey:
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AllowWindowsKey = true;
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break;
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case Parameters.AllowAltTabAndWindows:
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AllowAltTab = true;
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AllowWindowsKey = true;
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break;
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case Parameters.PassAllKeysToNextApp:
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PassAllKeysToNextApp = true;
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break;
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}
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}
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#endregion
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#region Check Modifier keys
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/// <summary>
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/// Checks whether Alt, Shift, Control or CapsLock
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/// is enabled at the same time as another key.
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/// Modify the relevant sections and return type
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/// depending on what you want to do with modifier keys.
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/// </summary>
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private void CheckModifiers()
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{
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StringBuilder sb = new StringBuilder();
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if ((NativeMethods.GetKeyState(VK_CAPITAL) & 0x0001) != 0)
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{
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//CAPSLOCK is ON
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sb.AppendLine("Capslock is enabled.");
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}
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if ((NativeMethods.GetKeyState(VK_SHIFT) & 0x8000) != 0)
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{
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//SHIFT is pressed
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sb.AppendLine("Shift is pressed.");
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}
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if ((NativeMethods.GetKeyState(VK_CONTROL) & 0x8000) != 0)
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{
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//CONTROL is pressed
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sb.AppendLine("Control is pressed.");
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}
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if ((NativeMethods.GetKeyState(VK_MENU) & 0x8000) != 0)
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{
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//ALT is pressed
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sb.AppendLine("Alt is pressed.");
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}
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Console.WriteLine(sb.ToString());
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}
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#endregion Check Modifier keys
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#region Hook Callback Method
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/// <summary>
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/// Processes the key event captured by the hook.
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/// </summary>
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private IntPtr HookCallback(
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int nCode, IntPtr wParam, ref KBDLLHOOKSTRUCT lParam)
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{
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bool AllowKey = PassAllKeysToNextApp;
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//Filter wParam for KeyUp events only
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if (nCode >= 0)
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{
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if (wParam == (IntPtr)WM_KEYUP || wParam == (IntPtr)WM_SYSKEYUP)
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{
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// Check for modifier keys, but only if the key being
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// currently processed isn't a modifier key (in other
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// words, CheckModifiers will only run if Ctrl, Shift,
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// CapsLock or Alt are active at the same time as
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// another key)
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if (!(lParam.vkCode >= 160 && lParam.vkCode <= 164))
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{
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CheckModifiers();
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}
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// Check for key combinations that are allowed to
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// get through to Windows
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//
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// Ctrl+Esc or Windows key
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if (AllowWindowsKey)
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{
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switch (lParam.flags)
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{
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//Ctrl+Esc
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case 0:
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if (lParam.vkCode == 27)
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AllowKey = true;
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break;
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//Windows keys
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case 1:
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if ((lParam.vkCode == 91) || (lParam.vkCode == 92))
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AllowKey = true;
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break;
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}
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}
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// Alt+Tab
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if (AllowAltTab)
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{
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if ((lParam.flags == 32) && (lParam.vkCode == 9))
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AllowKey = true;
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}
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OnKeyIntercepted(new KeyboardHookEventArgs(lParam.vkCode, AllowKey));
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}
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//If this key is being suppressed, return a dummy value
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if (AllowKey == false)
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return (System.IntPtr)1;
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}
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//Pass key to next application
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return NativeMethods.CallNextHookEx(hookID, nCode, wParam, ref lParam);
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}
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#endregion
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#region Event Handling
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/// <summary>
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/// Raises the KeyIntercepted event.
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/// </summary>
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/// <param name="e">An instance of KeyboardHookEventArgs</param>
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public void OnKeyIntercepted(KeyboardHookEventArgs e)
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{
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if (KeyIntercepted != null)
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KeyIntercepted(e);
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}
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/// <summary>
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/// Delegate for KeyboardHook event handling.
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/// </summary>
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/// <param name="e">An instance of InterceptKeysEventArgs.</param>
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public delegate void KeyboardHookEventHandler(KeyboardHookEventArgs e);
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/// <summary>
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/// Event arguments for the KeyboardHook class's KeyIntercepted event.
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/// </summary>
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public class KeyboardHookEventArgs : System.EventArgs
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{
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private string keyName;
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private int keyCode;
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private bool passThrough;
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/// <summary>
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/// The name of the key that was pressed.
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/// </summary>
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public string KeyName
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{
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get { return keyName; }
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}
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/// <summary>
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/// The virtual key code of the key that was pressed.
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/// </summary>
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public int KeyCode
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{
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get { return keyCode; }
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}
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/// <summary>
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/// True if this key combination was passed to other applications,
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/// false if it was trapped.
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/// </summary>
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public bool PassThrough
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{
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get { return passThrough; }
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}
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public KeyboardHookEventArgs(int evtKeyCode, bool evtPassThrough)
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{
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keyName = ((Keys)evtKeyCode).ToString();
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keyCode = evtKeyCode;
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passThrough = evtPassThrough;
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}
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}
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#endregion
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#region IDisposable Members
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/// <summary>
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/// Releases the keyboard hook.
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/// </summary>
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public void Dispose()
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{
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NativeMethods.UnhookWindowsHookEx(hookID);
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}
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#endregion
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#region Native methods
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[ComVisibleAttribute(false),
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System.Security.SuppressUnmanagedCodeSecurity()]
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internal class NativeMethods
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{
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[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
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public static extern IntPtr GetModuleHandle(string lpModuleName);
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[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
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public static extern IntPtr SetWindowsHookEx(int idHook,
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HookHandlerDelegate lpfn, IntPtr hMod, uint dwThreadId);
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[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
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[return: MarshalAs(UnmanagedType.Bool)]
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public static extern bool UnhookWindowsHookEx(IntPtr hhk);
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[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
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public static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode,
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IntPtr wParam, ref KBDLLHOOKSTRUCT lParam);
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[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true, CallingConvention = CallingConvention.Winapi)]
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public static extern short GetKeyState(int keyCode);
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}
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#endregion
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}
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}
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