VB.NET如何使用SendMessage发送密钥46（Chr（46））

Question

I am Automating IBM iSeries Emulators using VB.net, created GUI that embeds the external iSeries Emulator Window in a WindowsForm Panel using the "SetParent" API .. To communicate with the iSeries Window I use the SendMessage API to send Key's to the Screen. I am aware of the sendkeys.keys in .net, but this way I dont have to SetForegroundWindow and reactivate my Form.

My program reads the output of a scale and validates if the received data is good, if so it will send the output to the iSeries Screen using this code (UserApi is my Lib):

For Each element As Char In CStr(txtto400.Text)
    UserApi.SendMessage(as400WindowHandle, 256, CType(Convert.ToInt32(element), IntPtr), CType(0, IntPtr))
Next

I done this a few times on other projects and this method works good, but in my TextBox (txtto400.Text) my weight has a Value like "000.88 KG". SendMessage will not send the key "46" which is a period (.) Instead it would be "00088 KG"

Does anyone have an idea why this dont work? Any suggestions what I could do?

EDIT:

Thanks to Paul B. which gave me the hint.

Here is how I resolved it.

My SendMessage function looks like this:

<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function SendMessage( _
   ByVal hwnd As IntPtr, _
   ByVal wMsg As UInt32, _
   ByVal wParam As IntPtr, _
   ByVal lParam As IntPtr) As IntPtr
End Function

I created a variable that holds the VK_OEM_PERIOD:

Public Const VK_OEM_PERIOD = &HBE

Created a Function that will check the Chr:

Public Function vk_key(key As Char) As Integer
 Select Case key
     Case Is = Chr(46)
         Return VK_OEM_PERIOD
     Case Else
        Return AscW(key)
 End Select
End Function

here is how I pass it to the iSeries Window:

For Each element As Char In txtto400.Text
   UserApi.SendMessage(as400WindowHandle, 256, vk_key(element), 0)
Next

Answer 1

The WM_KEYDOWN message expects "The virtual-key code of the nonsystem key" as wParam (see MSDN ).

This happens to correspond to the key character's ASCII value for alphanumeric signs but not for all other keys. For a period I think you need to send VK_OEM_PERIOD .

You can find the table of virtual-key codes here: http://msdn.microsoft.com/en-us/library/windows/desktop/dd375731%28v=vs.85%29.aspx