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using System;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace MouseKeyboardLibrary
{
/// <summary>
/// Captures global keyboard events
/// </summary>
public class KeyboardHook : GlobalHook
{
#region Events
public event KeyEventHandler KeyDown;
public event KeyEventHandler KeyUp;
public event KeyPressEventHandler KeyPress;
#endregion
#region Constructor
public KeyboardHook()
{
_hookType = WH_KEYBOARD_LL;
}
#endregion
#region Methods
protected override int HookCallbackProcedure(int nCode, int wParam, IntPtr lParam)
{
bool handled = false;
if (nCode > -1 && (KeyDown != null || KeyUp != null || KeyPress != null))
{
KeyboardHookStruct keyboardHookStruct =
(KeyboardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyboardHookStruct));
// Is Control being held down?
bool control = ((GetKeyState(VK_LCONTROL) & 0x80) != 0) ||
((GetKeyState(VK_RCONTROL) & 0x80) != 0);
// Is Shift being held down?
bool shift = ((GetKeyState(VK_LSHIFT) & 0x80) != 0) ||
((GetKeyState(VK_RSHIFT) & 0x80) != 0);
// Is Alt being held down?
bool alt = ((GetKeyState(VK_LALT) & 0x80) != 0) ||
((GetKeyState(VK_RALT) & 0x80) != 0);
// Is CapsLock on?
bool capslock = (GetKeyState(VK_CAPITAL) != 0);
// Create event using keycode and control/shift/alt values found above
KeyEventArgs e = new KeyEventArgs(
(Keys)(
keyboardHookStruct.vkCode |
(control ? (int)Keys.Control : 0) |
(shift ? (int)Keys.Shift : 0) |
(alt ? (int)Keys.Alt : 0)
));
// Handle KeyDown and KeyUp events
switch (wParam)
{
case WM_KEYDOWN:
case WM_SYSKEYDOWN:
if (KeyDown != null)
{
KeyDown(this, e);
handled = handled || e.Handled;
}
break;
case WM_KEYUP:
case WM_SYSKEYUP:
if (KeyUp != null)
{
KeyUp(this, e);
handled = handled || e.Handled;
}
break;
}
// Handle KeyPress event
if (wParam == WM_KEYDOWN &&
!handled &&
KeyPress != null)
{
byte[] keyState = new byte[256];
byte[] inBuffer = new byte[2];
GetKeyboardState(keyState);
if (ToAscii(keyboardHookStruct.vkCode,
keyboardHookStruct.scanCode,
keyState,
inBuffer,
keyboardHookStruct.flags) == 1)
{
char key = (char)inBuffer[0];
if ((capslock ^ shift) && Char.IsLetter(key))
key = Char.ToUpper(key);
KeyPressEventArgs e2 = new KeyPressEventArgs(key);
KeyPress(this, e2);
handled = handled || e.Handled;
}
}
}
if (handled)
{
return 1;
}
else
{
return CallNextHookEx(_handleToHook, nCode, wParam, lParam);
}
}
#endregion
}
}
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