Is there a way to get a standard Windows Forms application to detect if the Shift key is being held down on application startup - without using Windows hooks?
I ideally would like the workflow to change from normal if the shift key is held down when the EXE file is run.
Here is an article about reading the key states (and mouse) directly.
The ModifierKeys property looks ideal:
private void Form1_Load(object sender, EventArgs e)
{
if ( (ModifierKeys & Keys.Shift) != 0)
{
MessageBox.Show("Shift is pressed");
}
}
I realize this is super old, but it bothered me a little bit to see people struggling with this. ModifierKeys is a bit field, so relying on .ToString() or == to see if the Shift key is pressed is, at best, unreliable and isn't the correct use of a bit field:
public enum ModifierKeys
{
/// <summary>No modifiers are pressed.</summary>
None = 0,
/// <summary>The ALT key.</summary>
Alt = 1,
/// <summary>The CTRL key.</summary>
Control = 2,
/// <summary>The SHIFT key.</summary>
Shift = 4,
/// <summary>The Windows logo key.</summary>
// Windows = 8, No longer leaked
}
Either none or any combination of Alt, Control, or Shift may be pressed, so the check should be:
if ((ModifierKeys & Keys.Shift) != 0)
{
MessageBox.Show("Shift is pressed");
}
I will up-vote Dan's answer as soon as I earn the right to do so :-) .Net 4+ includes the HasFlag() method as well, but I am accustomed to bitwise operations so I haven't used it. For more information on bitwise operations, flags, (with) truth tables, and other tidbits see:
What you see in the source is even more intriguing:
/// <devdoc>
/// Retrieves the current state of the modifier keys. This will check the
/// current state of the shift, control, and alt keys.
/// </devdoc>
public static Keys ModifierKeys {
get {
Keys modifiers = 0;
// SECURITYNOTE : only let state of Shift-Control-Alt out...
//
if (UnsafeNativeMethods.GetKeyState((int)Keys.ShiftKey) < 0) modifiers |= Keys.Shift;
if (UnsafeNativeMethods.GetKeyState((int)Keys.ControlKey) < 0) modifiers |= Keys.Control;
if (UnsafeNativeMethods.GetKeyState((int)Keys.Menu) < 0) modifiers |= Keys.Alt;
return modifiers;
}
}
This implementation ONLY emits the state of Shift, Control, and Alt. The Windows' key state is not included.
If you want to detect the key state BEFORE a form or control is created, maybe in the Main() method, you can go crazy.
Maybe you want to to this:
if (VirtualKeyState.VK_SHIFT.IsKeyPressed())
{
Debugger.Launch();
}
Create a simple extension method:
public static class KeyAssist
{
public const int KEY_PRESSED = 0x8000;
public static bool IsKeyPressed(this VirtualKeyState key) => Convert.ToBoolean(Native.GetKeyState(key) & KEY_PRESSED);
}
Import:
[DllImport("user32.dll")]
public static extern short GetKeyState(VirtualKeyState virtualKeyState);
Create the following enum (or some sub-section if you please) (from PInvoke):
public enum VirtualKeyState
{
VK_LBUTTON = 0x01,
VK_RBUTTON = 0x02,
VK_CANCEL = 0x03,
VK_MBUTTON = 0x04,
VK_XBUTTON1 = 0x05,
VK_XBUTTON2 = 0x06,
VK_BACK = 0x08,
VK_TAB = 0x09,
VK_CLEAR = 0x0C,
VK_RETURN = 0x0D,
VK_SHIFT = 0x10,
VK_CONTROL = 0x11,
VK_MENU = 0x12,
VK_PAUSE = 0x13,
VK_CAPITAL = 0x14,
VK_KANA = 0x15,
VK_HANGEUL = 0x15,
VK_HANGUL = 0x15,
VK_JUNJA = 0x17,
VK_FINAL = 0x18,
VK_HANJA = 0x19,
VK_KANJI = 0x19,
VK_ESCAPE = 0x1B,
VK_CONVERT = 0x1C,
VK_NONCONVERT = 0x1D,
VK_ACCEPT = 0x1E,
VK_MODECHANGE = 0x1F,
VK_SPACE = 0x20,
VK_PRIOR = 0x21,
VK_NEXT = 0x22,
VK_END = 0x23,
VK_HOME = 0x24,
VK_LEFT = 0x25,
VK_UP = 0x26,
VK_RIGHT = 0x27,
VK_DOWN = 0x28,
VK_SELECT = 0x29,
VK_PRINT = 0x2A,
VK_EXECUTE = 0x2B,
VK_SNAPSHOT = 0x2C,
VK_INSERT = 0x2D,
VK_DELETE = 0x2E,
VK_HELP = 0x2F,
VK_LWIN = 0x5B,
VK_RWIN = 0x5C,
VK_APPS = 0x5D,
VK_SLEEP = 0x5F,
VK_NUMPAD0 = 0x60,
VK_NUMPAD1 = 0x61,
VK_NUMPAD2 = 0x62,
VK_NUMPAD3 = 0x63,
VK_NUMPAD4 = 0x64,
VK_NUMPAD5 = 0x65,
VK_NUMPAD6 = 0x66,
VK_NUMPAD7 = 0x67,
VK_NUMPAD8 = 0x68,
VK_NUMPAD9 = 0x69,
VK_MULTIPLY = 0x6A,
VK_ADD = 0x6B,
VK_SEPARATOR = 0x6C,
VK_SUBTRACT = 0x6D,
VK_DECIMAL = 0x6E,
VK_DIVIDE = 0x6F,
VK_F1 = 0x70,
VK_F2 = 0x71,
VK_F3 = 0x72,
VK_F4 = 0x73,
VK_F5 = 0x74,
VK_F6 = 0x75,
VK_F7 = 0x76,
VK_F8 = 0x77,
VK_F9 = 0x78,
VK_F10 = 0x79,
VK_F11 = 0x7A,
VK_F12 = 0x7B,
VK_F13 = 0x7C,
VK_F14 = 0x7D,
VK_F15 = 0x7E,
VK_F16 = 0x7F,
VK_F17 = 0x80,
VK_F18 = 0x81,
VK_F19 = 0x82,
VK_F20 = 0x83,
VK_F21 = 0x84,
VK_F22 = 0x85,
VK_F23 = 0x86,
VK_F24 = 0x87,
VK_NUMLOCK = 0x90,
VK_SCROLL = 0x91,
VK_OEM_NEC_EQUAL = 0x92,
VK_OEM_FJ_JISHO = 0x92,
VK_OEM_FJ_MASSHOU = 0x93,
VK_OEM_FJ_TOUROKU = 0x94,
VK_OEM_FJ_LOYA = 0x95,
VK_OEM_FJ_ROYA = 0x96,
VK_LSHIFT = 0xA0,
VK_RSHIFT = 0xA1,
VK_LCONTROL = 0xA2,
VK_RCONTROL = 0xA3,
VK_LMENU = 0xA4,
VK_RMENU = 0xA5,
VK_BROWSER_BACK = 0xA6,
VK_BROWSER_FORWARD = 0xA7,
VK_BROWSER_REFRESH = 0xA8,
VK_BROWSER_STOP = 0xA9,
VK_BROWSER_SEARCH = 0xAA,
VK_BROWSER_FAVORITES = 0xAB,
VK_BROWSER_HOME = 0xAC,
VK_VOLUME_MUTE = 0xAD,
VK_VOLUME_DOWN = 0xAE,
VK_VOLUME_UP = 0xAF,
VK_MEDIA_NEXT_TRACK = 0xB0,
VK_MEDIA_PREV_TRACK = 0xB1,
VK_MEDIA_STOP = 0xB2,
VK_MEDIA_PLAY_PAUSE = 0xB3,
VK_LAUNCH_MAIL = 0xB4,
VK_LAUNCH_MEDIA_SELECT = 0xB5,
VK_LAUNCH_APP1 = 0xB6,
VK_LAUNCH_APP2 = 0xB7,
VK_OEM_1 = 0xBA,
VK_OEM_PLUS = 0xBB,
VK_OEM_COMMA = 0xBC,
VK_OEM_MINUS = 0xBD,
VK_OEM_PERIOD = 0xBE,
VK_OEM_2 = 0xBF,
VK_OEM_3 = 0xC0,
VK_OEM_4 = 0xDB,
VK_OEM_5 = 0xDC,
VK_OEM_6 = 0xDD,
VK_OEM_7 = 0xDE,
VK_OEM_8 = 0xDF,
VK_OEM_AX = 0xE1,
VK_OEM_102 = 0xE2,
VK_ICO_HELP = 0xE3,
VK_ICO_00 = 0xE4,
VK_PROCESSKEY = 0xE5,
VK_ICO_CLEAR = 0xE6,
VK_PACKET = 0xE7,
VK_OEM_RESET = 0xE9,
VK_OEM_JUMP = 0xEA,
VK_OEM_PA1 = 0xEB,
VK_OEM_PA2 = 0xEC,
VK_OEM_PA3 = 0xED,
VK_OEM_WSCTRL = 0xEE,
VK_OEM_CUSEL = 0xEF,
VK_OEM_ATTN = 0xF0,
VK_OEM_FINISH = 0xF1,
VK_OEM_COPY = 0xF2,
VK_OEM_AUTO = 0xF3,
VK_OEM_ENLW = 0xF4,
VK_OEM_BACKTAB = 0xF5,
VK_ATTN = 0xF6,
VK_CRSEL = 0xF7,
VK_EXSEL = 0xF8,
VK_EREOF = 0xF9,
VK_PLAY = 0xFA,
VK_ZOOM = 0xFB,
VK_NONAME = 0xFC,
VK_PA1 = 0xFD,
VK_OEM_CLEAR = 0xFE
}
Anyway, this is just for reference so there isn't so much guessing going on.
HTH,
Colby
Check Control.ModifierKeys ...
[STAThread]
static void Main(string[] args)
{
if (Control.ModifierKeys == Keys.ShiftKey)
{
// Do something special
}
}
Control.ModifierKeys was always None during start-up), but this did work when I launched the executable from Windows Explorer while holding down the Shift key. –
Fricke I know this post is rather old but I ran into this issue and fixed it by modifying Jamie's code:
[STAThread]
static void Main(string[] args)
{
if (Control.ModifierKeys.ToString() == "Shift")
{
// Do something special
}
}
Here is an article about reading the key states (and mouse) directly.
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