by SKoW (11 Submissions)
Category: Windows API Call/Explanation
Compatability: Visual Basic 3.0
Difficulty: Intermediate
Date Added: Wed 3rd February 2021
Rating: 
(3 Votes)
This is a *baisc* sample of how to use the PostMessage API calls (same as SendMessage) to send text to a Textbox (or any hWnd actually).
Note: I tracked down the 3 WM_ messages through SPY++ and Notepad. Differnt applications may require more/less WM_ messages. A VB Textbox only needs WM_KEYDOWN but I added the other code incase. =].. Sorry about the cheap Variable names, this was programmed at 5am :)
Assumes
To make life easy, Assume you have a Form with a Text box on it (Text2) which will have the text to SEND to another text box (which we will put on the form so the hWnd is easy to get: Text1)
Side Effects
May have some issues if you put in random hWnds.
API Declarations' I like Postmessage over Sendmessage
Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Const WM_KEYDOWN = &H100
Public Const WM_KEYUP = &H101
Public Const WM_CHAR = &H102
VBcoders
Sub SendText(hWnd As Long, Text As String)
If hWnd = 0 Then MsgBox "no hWnd supplied": Exit Sub
' got hWnd, start sending messages
Dim zwParam As Long ' so no dupe deffs use z infrount =]
Dim zlParam As Long
Dim xwParam As Long ' used for WM_CHAR
For I = 1 To Len(Text)
' First, get the lParam for WM_KEYDOWN
zwParam = GetVKCode(Mid$(Text, I, 1))
xwParam = zwParam And &H20 ' wants Hex20 added to it so A7 goes to C7 and 15 -> 35 (hex values)
zlParam = GetScanCode(Mid$(Text, I, 1))
PostMessage hWnd, WM_KEYDOWN, zwParam, zlParam
' Used in notepad, doesn't seem to be used in this example
'PostMessage hWnd, WM_CHAR, xwParam, zlParam
' Used in notepad, but doubles the chars in this example..
'zlParam = zlParam And &HC0000000 ' wants hex-C (7x0's) added.
'PostMessage hWnd, WM_KEYUP, zwParam, zlParam
DoEvents
Next
End Sub
Function GetVKCode(ByVal Char As String) As Long
On Error Resume Next
Char = UCase(Left$(Char, 1))
GetVKCode = Asc(Char)
End Function
Function GetScanCode(bChar As String) As Long
' To get scancodes:
' Start SPY++ on Notepad
'Type in all chars and then stop SPY++ logging. It will tell you all scancodes
' recorded during the logging.. long but ah well..
' Note: Scancode 1E = &H1E0001, 30 = &H300001
'
Select Case LCase$(Left$(bChar, 1))
Case "a"
GetScanCode = &H1E0001
Case "b"
GetScanCode = &H300001
Case "c"
GetScanCode = &H2E0001
Case "d"
GetScanCode = &H200001
Case "e"
GetScanCode = &H120001
Case "f"
GetScanCode = &H210001
Case "g"
GetScanCode = &H220001
Case "h"
GetScanCode = &H230001
Case "i"
GetScanCode = &H170001
Case "j"
GetScanCode = &H240001
Case "k"
GetScanCode = &H250001
Case "l"
GetScanCode = &H260001
Case "m"
GetScanCode = &H320001
Case "n"
GetScanCode = &H310001
Case "o"
GetScanCode = &H180001
Case "p"
GetScanCode = &H190001
Case "q"
GetScanCode = &H100001
Case "r"
GetScanCode = &H130001
Case "s"
GetScanCode = &H1F0001
Case "t"
GetScanCode = &H140001
Case "u"
GetScanCode = &H160001
Case "v"
GetScanCode = &H2F0001
Case "w"
GetScanCode = &H110001
Case "x"
GetScanCode = &H2D0001
Case "y"
GetScanCode = &H150001
Case "z"
GetScanCode = &H2C0001
Case Else
GetScanCode = 0 ' no scode at the mo =(
End Select
End Function
