How to automatically copy clipboard text into textbox using timer

Question

Using VB.Net, am trying to get the text in clipboard into a specific textbox. Once text get into clipboard, I want it to be getting pasted and queuing automatically into the textbox, using timer. The below code was supposed to do as expected but only works fine if the clipboard text is a line of text. If the text is more than a line of text, the same text pastes continuously instead of just once into the textbox. See code.... Thank you.

Private Sub tmrClipboardHistory_Tick(sender As Object, e As EventArgs) Handles tmrClipboardHistory.Tick          

If My.Computer.Clipboard.ContainsText Then              
  If textbox1.Text.Contains(My.Computer.Clipboard.GetText) Then                 
   'do nothing             
  Else                 
   textbox1.Text += My.Computer.Clipboard.GetText()
   textbox1.Text += ControlChars.NewLine & ControlChars.NewLine             
  End If          
End If

End Sub    

Answer 1

You can use SetClipboardViewer to know about clipboard changes. You will receive a WM_DRAWCLIPBOARD message when the content changes.

Imports System.Runtime.InteropServices


Public Class Form1

    Private hwndNextChain As IntPtr

    Public Sub New()
        InitializeComponent()
    End Sub

    Protected Overrides Sub OnHandleCreated(e As EventArgs)
        MyBase.OnHandleCreated(e)
        hwndNextChain = SetClipboardViewer(Me.Handle)
    End Sub

    Protected Overrides Sub OnHandleDestroyed(e As EventArgs)
        MyBase.OnHandleDestroyed(e)
        ChangeClipboardChain(Me.Handle, hwndNextChain)
    End Sub

    Protected Overrides Sub WndProc(ByRef m As Message)
        Select Case m.Msg
            Case WM_DRAWCLIPBOARD
                If hwndNextChain <> IntPtr.Zero Then
                    SendMessage(hwndNextChain, m.Msg, m.WParam, m.LParam)
                End If
                If Clipboard.ContainsText() Then
                    Dim clipboardText As String = Clipboard.GetText()
                    TextBox1.AppendText(clipboardText & vbCrLf)
                    Debug.WriteLine($"{Now} Change Clipboard")
                End If

            Case WM_CHANGECBCHAIN
                If m.WParam = hwndNextChain Then
                    hwndNextChain = m.LParam
                ElseIf hwndNextChain <> IntPtr.Zero Then
                    SendMessage(hwndNextChain, m.Msg, m.WParam, m.LParam)
                End If
        End Select
        MyBase.WndProc(m)
    End Sub


    <DllImport("User32.Dll")>
    Private Shared Function SendMessage(hWnd As IntPtr, Msg As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr
    End Function

    <DllImport("user32.dll", SetLastError:=True)>
    Private Shared Function SetClipboardViewer(hWndNewViewer As IntPtr) As IntPtr
    End Function

    <DllImport("user32.dll", SetLastError:=True)>
    Private Shared Function ChangeClipboardChain(hWndRemove As IntPtr, hWndNewNext As IntPtr) As Boolean
    End Function

    Private Const WM_DRAWCLIPBOARD As Integer = &H308
    Private Const WM_CHANGECBCHAIN As Integer = &HD

End Class

Answer 2

Hi

Using the code below works for me.

		With Timer1
			.Interval = 1000 ' ever 1 second
			.Enabled = True
		End With
		With TextBox1
			.Multiline = True
			.Font = New Font(.Font.FontFamily, 22)
			.ScrollBars = ScrollBars.Both
		End With
' ------------------------------------------
	Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
 		If Not TextBox1.Text = Clipboard.GetText Then TextBox1.Text = Clipboard.GetText
 	End Sub