Keyboard Hook to intercept clipboard pasting

[JimAvanti]

I have a need to copy a numeric value to the clipboard and upon pasting it into a document having it increment the number with each paste. I am using a keyboard hook to intercept the CTRL-V, Un-register the hook, read the clipboard and if it can be incremented then do so, paste the clipboard (by use of SendKeys to send a CTRL-V), then Re-register the keyboard hook.

This works, however by using SendKeys to paste the clipboard it kills the ability for key-repeat. I can keep pasting one number at a time as long as I lift the CTRL key each time, otherwise the key repeat kicks in and pastes a bunch of v's.

I am trying to find an alternative to using SendKeys as a way of continuing the paste operation or a way of letting the computer recognize the CTRL key as part of the key repeat. Anyone?

Thanks,

Jim

Imports System.Runtime.InteropServices
Public Class Form1
    Public Const VK_ALT As Integer = &H1
    Public Const VK_CTRL As Integer = &H2
    Public Const VK_SHIFT As Integer = &H4
    Public Const VK_CTRL_ALT As Integer = &H1 + &H2
    Public Const VK_CTRL_SHIFT As Integer = &H2 + &H4
    Public Const WM_HOTKEY As Integer = &H312
    <DllImport("User32.dll")> _
    Public Shared Function RegisterHotKey(ByVal hwnd As IntPtr, ByVal id As Integer, ByVal fsModifiers As Integer, ByVal vk As Integer) As Integer
    End Function
    <DllImport("User32.dll")> _
    Public Shared Function UnregisterHotKey(ByVal hwnd As IntPtr, ByVal id As Integer) As Integer
    End Function
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        RegisterHotKey(Me.Handle, 100, VK_CTRL, Keys.V)
    End Sub
    Private Sub Form1_FormClosing(sender As Object, e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        UnregisterHotKey(Me.Handle, 100)
    End Sub

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = WM_HOTKEY Then
            Dim id As IntPtr = m.WParam
            Dim iData As IDataObject = Clipboard.GetDataObject()
            Dim Numb As Integer = 0
            UnregisterHotKey(Me.Handle, 100)
            If id.ToString = "100" Then
                If iData.GetDataPresent(DataFormats.Text) Then
                    Try
                        Numb = CType(iData.GetData(DataFormats.Text), String) + 1
                        Clipboard.SetText(Numb.ToString)
                        System.Windows.Forms.SendKeys.Send("^v")
                    Catch ex As Exception
                        System.Windows.Forms.SendKeys.Send("^v")
                    End Try
                Else
                    System.Windows.Forms.SendKeys.Send("^v")
                End If
            End If
            RegisterHotKey(Me.Handle, 100, VK_CTRL, Keys.V)
            End If
            MyBase.WndProc(m)
    End Sub
End Class

[.paul.]

this should help. it's a clipboard hook:

Public Class Form1

    Private Const WM_DRAWCLIPBOARD As Integer = &H308
    Private Declare Function SetClipboardViewer Lib "user32" Alias "SetClipboardViewer" (ByVal hwnd As Integer) As Integer

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = WM_DRAWCLIPBOARD Then
            'clipboard has changed
            Dim value As Decimal
            If Decimal.TryParse(Clipboard.GetText, value) Then
                'clipboard contains a decimal

            End If
        End If
        MyBase.WndProc(m)
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim hWnd As Integer = SetClipboardViewer(Me.Handle.ToInt32)
        While hWnd <> Me.Handle.ToInt32
            hWnd = SetClipboardViewer(Me.Handle.ToInt32)
        End While
    End Sub

End Class

[JimAvanti]

Paul,
Thanks for the code example. It looks like it may be pointing me in the right direction, but I was not able to get it to work correctly. I added a couple of lines of code to increment the value and copy it back to the clipboard:
value = value + 1
Clipboard.SetText(value.ToString)

It did increment on the first paste, but not on consecutive pastes. It seems that this clipboard hook will intercept manual modifications to the clipboard (^C, ^X). I need something that will intercept every paste so that I can increment the value with each paste, whether a single paste or a repeat by holding down the ^V keys. Am I using your code as intended?

Thanks,
Jim

[.paul.]

I wouldn't increment the value and write it back to the clipboard. That would cause an infinite recursion

[JimAvanti]

On the original code I posted (The keyboard hook), I was able to accomplish what I was trying to do, except I had to lift the control button with each paste. I was intercepting the ^v, modifying the clipboard, and using SendKeys.Send("^v") to resume the paste command. I disabled the hook and re-enabled it after modifying the clipboard to eliminate infinite looping. The problem I was having was with resuming the paste command by using sendkeys, the CONTRL key was no longer seen as part of the keyboard repeat so instead on repeated ^v I was only getting the v’s. I also tried using a different hotkey so that I wouldn’t need to disable the hook between pastes, but I still had the same problem with key-repeats.

The Clipboard hook you sent works with key-repeats, but it only repeats the same last value and only increments if I copy a new value to the clipboard manually by pressing ^c or ^X. I am trying to increment every paste value whether a single ^v or repeated by holding down ^v. Being able to hook the clipboard paste rather than clipboard changes would work, but only if I could resume the paste after modifying the clipboard contents. Maybe an interrupt to the paste would work if that is possible. Any other ideas?

Paul,
Thanks for the code example. It looks like it may be pointing me in the right direction, but I was not able to get it to work correctly. I added a couple of lines of code to increment the value and copy it back to the clipboard:
value = value + 1
Clipboard.SetText(value.ToString)

It did increment on the first paste, but not on consecutive pastes. It seems that this clipboard hook will intercept manual modifications to the clipboard (^C, ^X). I need something that will intercept every paste so that I can increment the value with each paste, whether a single paste or a repeat by holding down the ^V keys. Am I using your code as intended?

Thanks,
Jim

[.paul.]

I don't think your original code is possible. RegisterHotkey doesn't recognize the ctrl key being pressed after the first event, and all of the workarounds that I can think of that might emulate the key being re-pressed don't work