Question

We have a situation where the hardware Return button performs a certain action, However this action is also triggerd wher using the Return button on the SIP control.

Is there anyway to determine if the KeyPressEventArg has come from the SIP?

    /// <summary>
    /// Handles the Enter button being pressed as navigation to complete the signature capture
    /// </summary>
    /// <param name="e">The key event args to quaify what button was pressed.</param>
    public override void HandleKeyPress(KeyPressEventArgs e)
    {
        if (e.KeyChar == '\r') // and is not SIP '\r'
        {
            // need to handle only hard button not SIP
        }
    }

Many thanks for any enlightenment on this

Answer 1

Ok after another day of experimenting I have found a stable way to indicate SIP(InputPanel) key presses from hardbutton key presses.

Using PeekMessage we can check the keyvalue in the message queue and check for the LParam of ‘1’ which always seems to be 1 when coming from the SIP (accross all devices).

Code below

public class InputHelper
{
    #region Static Members

    /// <summary>
    /// Determines whether the key value pressed originated from the SIP
    /// </summary>
    /// <param name="keyValue">The key value.</param>
    /// <param name="handle">The widget handle.</param>
    /// <returns>
    ///   <c>true</c> if is sip key press; otherwise, <c>false</c>.
    /// </returns>
    public static bool IsSipKeyPress(int keyValue, IntPtr handle)
    {
        NativeMessage m;
        if (PeekMessage(out m, handle, 0, 0, PM_NOREMOVE))
        {
            // All SIP inputs have LParam of 1, so ignore these
            if (m.msg == WM_CHAR && m.wParam == (IntPtr)keyValue && m.lParam == (IntPtr)1)
            {
                return true;
            }
        }
        return false;
    }

    #endregion


    #region P-Invoke

    const uint PM_NOREMOVE = 0x0000;
    const uint WM_CHAR = 258;

    [DllImport("coredll.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool PeekMessage(out NativeMessage lpMsg, IntPtr hWnd, uint wMsgFilterMin, uint wMsgFilterMax, uint wRemoveMsg);

    [StructLayout(LayoutKind.Sequential)]
    public struct NativeMessage
    {
        public IntPtr handle;
        public uint msg;
        public IntPtr wParam;
        public IntPtr lParam;
        public uint time;
        public System.Drawing.Point p;
    }

    #endregion
}

Usage:

/// <summary>
/// Handle a KeyDown event and check for Hardbutton Return key
/// </summary>
/// <param name="e">A KeyEventArgs instance</param>
public override void HandleKeyDown(KeyEventArgs e)
{
    if (e.KeyValue == 13)
    {
        if (!InputHelper.IsSipKeyPress(13, base.Handle))
        {
            CompleteProcess();
        }
    }
    base.HandleKeyDown(e);
}  

Hope this helps someone else 🙂