Disabling Accessibility Shortcuts in .NET Application?

Question

This msdn article -- http://msdn.microsoft.com/en-us/library/bb219746(VS.85).aspx#Disabling_Accessibility_Shortcut_Keys -- provides information for C++ programmers on how to temporarily disable the windows shortcuts for accessibility (such as holding Shift for 8 seconds, or pressing Shift more than 5 times in quick succession).

Surely there's some easy way to do this in C#, but I can't find any resources on this. I'm using DirectInput in a non-fullscreen application.

All I want to do is not have the annoying popups come up; I'd prefer something that doesn't have to muck with the windows settings, though, just in case the application shuts down in a non-graceful manner (I'd prefer not to have the user's settings be permanently altered in those situations).

Any thoughts?

Answer 1

You will have to do the same thing that is done in the link you reference. The SystemParametersInfo API function can be called through the P/Invoke layer and you can find the definition here:

http://www.pinvoke.net/default.aspx/user32/SystemParametersInfo.html

Answer 2

Just in case anyone else needs this, here's the converted C# code, which at last does work:

    [DllImport( "user32.dll", EntryPoint = "SystemParametersInfo", SetLastError = false )]
    private static extern bool SystemParametersInfo( uint action, uint param,
        ref SKEY vparam, uint init );

    [DllImport( "user32.dll", EntryPoint = "SystemParametersInfo", SetLastError = false )]
    private static extern bool SystemParametersInfo( uint action, uint param,
        ref FILTERKEY vparam, uint init );

    private const uint SPI_GETFILTERKEYS = 0x0032;
    private const uint SPI_SETFILTERKEYS = 0x0033;
    private const uint SPI_GETTOGGLEKEYS = 0x0034;
    private const uint SPI_SETTOGGLEKEYS = 0x0035;
    private const uint SPI_GETSTICKYKEYS = 0x003A;
    private const uint SPI_SETSTICKYKEYS = 0x003B;

    private static bool StartupAccessibilitySet = false;
    private static SKEY StartupStickyKeys;
    private static SKEY StartupToggleKeys;
    private static FILTERKEY StartupFilterKeys;

    private const uint SKF_STICKYKEYSON = 0x00000001;
    private const uint TKF_TOGGLEKEYSON = 0x00000001;
    private const uint SKF_CONFIRMHOTKEY = 0x00000008;
    private const uint SKF_HOTKEYACTIVE = 0x00000004;
    private const uint TKF_CONFIRMHOTKEY = 0x00000008;
    private const uint TKF_HOTKEYACTIVE = 0x00000004;
    private const uint FKF_CONFIRMHOTKEY = 0x00000008;
    private const uint FKF_HOTKEYACTIVE = 0x00000004;

    [StructLayout( LayoutKind.Sequential, CharSet = CharSet.Auto )]
    public struct SKEY
    {
        public uint cbSize;
        public uint dwFlags;
    }

    [StructLayout( LayoutKind.Sequential, CharSet = CharSet.Auto )]
    public struct FILTERKEY
    {
        public uint cbSize;
        public uint dwFlags;
        public uint iWaitMSec;
        public uint iDelayMSec;
        public uint iRepeatMSec;
        public uint iBounceMSec;
    }

    private static uint SKEYSize = sizeof( uint ) * 2;
    private static uint FKEYSize = sizeof( uint ) * 6;

    public static void ToggleAccessibilityShortcutKeys( bool ReturnToStarting )
    {
        if ( !StartupAccessibilitySet )
        {
            StartupStickyKeys.cbSize = Configuration.SKEYSize;
            StartupToggleKeys.cbSize = Configuration.SKEYSize;
            StartupFilterKeys.cbSize = Configuration.FKEYSize;
            SystemParametersInfo( SPI_GETSTICKYKEYS, SKEYSize, ref StartupStickyKeys, 0 );
            SystemParametersInfo( SPI_GETTOGGLEKEYS, SKEYSize, ref StartupToggleKeys, 0 );
            SystemParametersInfo( SPI_GETFILTERKEYS, FKEYSize, ref StartupFilterKeys, 0 );
            StartupAccessibilitySet = true;
        }

        if ( ReturnToStarting )
        {
            // Restore StickyKeys/etc to original state and enable Windows key
            SystemParametersInfo( SPI_SETSTICKYKEYS, SKEYSize, ref StartupStickyKeys, 0 );
            SystemParametersInfo( SPI_SETTOGGLEKEYS, SKEYSize, ref StartupToggleKeys, 0 );
            SystemParametersInfo( SPI_SETFILTERKEYS, FKEYSize, ref StartupFilterKeys, 0 );
        }
        else
        {
            // Disable StickyKeys/etc shortcuts but if the accessibility feature is on, 
            // then leave the settings alone as its probably being usefully used
            SKEY skOff = StartupStickyKeys;
            //if ( ( skOff & SKF_STICKYKEYSON ) == 0 )
            {
                // Disable the hotkey and the confirmation
                skOff.dwFlags &= ~SKF_HOTKEYACTIVE;
                skOff.dwFlags &= ~SKF_CONFIRMHOTKEY;


                SystemParametersInfo( SPI_SETSTICKYKEYS, SKEYSize, ref skOff, 0 );
            }
            SKEY tkOff = StartupToggleKeys;
            //if ( ( tkOff & TKF_TOGGLEKEYSON ) == 0 )
            {
                // Disable the hotkey and the confirmation
                tkOff.dwFlags &= ~TKF_HOTKEYACTIVE;
                tkOff.dwFlags &= ~TKF_CONFIRMHOTKEY;

                rs = SystemParametersInfo( SPI_SETTOGGLEKEYS, SKEYSize, ref tkOff, 0 );
            }

            FILTERKEY fkOff = StartupFilterKeys;
            //if ( ( fkOff & FKF_FILTERKEYSON ) == 0 )
            {
                // Disable the hotkey and the confirmation
                fkOff.dwFlags &= ~FKF_HOTKEYACTIVE;
                fkOff.dwFlags &= ~FKF_CONFIRMHOTKEY;

                SystemParametersInfo( SPI_SETFILTERKEYS, FKEYSize, ref fkOff, 0 );
            }
        }
    }

Do note that I was unable to convert three of the IF statements from C++ (those are commented out). Microsoft recommends those, but I don't know a way to make them work in C#. Additionally, I'm not using sizeof() on the structs (instead manually creating variables for their size), because to do that would require unsafe code, and I don't want that to be a requirement for my particular program.

Answer 3

You may look this also C#

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication1 {
  public partial class Form1 : Form {
    private const int MYKEYID = 0;    // In case you want to register more than one...
    public Form1() {
      InitializeComponent();
      RegisterHotKey(this.Handle, MYKEYID, MOD_ALT, Keys.Tab);
      this.FormClosing += Form1_FormClosing;
    }
    private void Form1_FormClosing(object sender, FormClosingEventArgs e) {
      UnregisterHotKey(this.Handle, MYKEYID);
    }
    protected override void WndProc(ref Message m) {
      if (m.Msg == WM_HOTKEY && m.WParam.ToInt32() == MYKEYID) {
        Console.Beep();
      }
      base.WndProc(ref m);
    }
    // P/Invoke declarations
    private const int WM_HOTKEY = 0x312;
    private const int MOD_ALT = 1;
    private const int MOD_CONTROL = 2;
    private const int MOD_SHIFT = 4;
    [DllImport("user32.dll")]
    private static extern int RegisterHotKey(IntPtr hWnd, int id, int modifier, Keys vk);
    [DllImport("user32.dll")]
    private static extern bool UnregisterHotKey(IntPtr hWnd, int id);
  }
}

found it here http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/47647b7e-b23f-4f80-9363-ffd5f11a2570

cheers