CODEWITHSUNDEEP
c#winapihook
Canada_Goose
Canada_Goose

Reputation: 21

GetKeyState() not evaluating correctly

the GetKeyState() in my code is not evaluating correctly .. when i use this :

 bool ctrlDown = GetKeyState(VK_LCONTROL) != 0 || GetKeyState(VK_RCONTROL) != 0;

in my code its not coming back with the correct info.. its fired on all key events and its being evaluated as true even when other keys are pressed.. can anyone see anything im doing wrong in this code ?

i load it up here :

    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern short GetKeyState(int nVirtKey);

Then i call the "VK_LCONTROL & VK_RCONTROL" var's and fill them :

    public const int VK_LCONTROL = 0xA2;
    public const int VK_RCONTROL = 0xA3;

and then i call it in this function: 

private int KbHookProc(int nCode, IntPtr wParam, IntPtr lParam)
    {
        var hookStruct = (KbLLHookStruct)Marshal.PtrToStructure(lParam, typeof(KbLLHookStruct));

        bool ctrlDown = GetKeyState(VK_LCONTROL) != 0 || GetKeyState(VK_RCONTROL) != 0;

        if (nCode >= 0 && wParam == (IntPtr)WM_KEYUP && hookStruct.vkCode == 0x56 && ctrlDown == true)
        {

                MessageBox.Show("Message : KEY UP");
                ComboHit = false;
        }

        // Pass to other keyboard handlers. Makes the Ctrl+V pass through.
        return CallNextHookEx(_hookHandle, nCode, wParam, lParam);        
    }

when i check so see what the " GetKeyState(VK_LCONTROL) " is returning .. its alternates back and forth between 0 & 1, i knwo that MS says it should do this : "Retrieves the status of the specified virtual key. The status specifies whether the key is up, down, or toggled (on, off—alternating each time the key is pressed). "

why would i want this ?.. and can i make it evaluate the keys up or down position accurately ?

Upvotes: 0

Views: 9077

Answers (3)

Chris Shain
Chris Shain

Reputation: 51349

Why not just use Control.ModifierKeys?

Something like this?

public partial class myForm : Form
{
    public myForm()
    {
        InitializeComponent();
    }

    private void myForm_Load(object sender, EventArgs e)
    {
        KeyPreview = true;
        KeyUp += (s, ek) =>
                     {
                         if (ek.KeyCode == Keys.V && ModifierKeys.HasFlag(Keys.Control))
                             MessageBox.Show("Yerp, it done happened");
                     };
    }
}

Upvotes: 1

Frederik Gheysels
Frederik Gheysels

Reputation: 56934

What exactly are you trying to do ? I think perhaps you could take a look at the GetKeyboardState method

https://stackoverflow.com/a/709641/55774

Upvotes: 0

jdigital
jdigital

Reputation: 12276

To test if a key is down, you need to check the high order bit:

(GetKeyState(vk) & 0x8000)

Upvotes: 9

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