Recently, I was modifying the old softphone source code (written in VB6) and encountered error using ‘SendKeys’ function. Sometimes, it sends multiple keystrokes for the same char resulting in application errors. Thought of using WinAPI’s to simulate keystrokes and got this one..works really well…
Const KEYEVENTF_KEYUP = &H2
Const INPUT_MOUSE = 0
Const INPUT_KEYBOARD = 1
Const INPUT_HARDWARE = 2
Private Type MOUSEINPUT
dx As Long
dy As Long
mouseData As Long
dwFlags As Long
time As Long
dwExtraInfo As Long
End Type
Private Type KEYBDINPUT
wVk As Integer
wScan As Integer
dwFlags As Long
time As Long
dwExtraInfo As Long
End Type
Private Type HARDWAREINPUT
uMsg As Long
wParamL As Integer
wParamH As Integer
End Type
Private Type GENERALINPUT
dwType As Long
xi(0 To 23) As Byte
End Type
Private Declare Function SendInput Lib "user32.dll" (ByVal nInputs As Long, pInputs As GENERALINPUT, ByVal cbSize As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (pDst As Any, pSrc As Any, ByVal ByteLen As Long)
Private Sub SendKey(bKey As Byte)
Dim GInput(0 To 1) As GENERALINPUT
Dim KInput As KEYBDINPUT
KInput.wVk = bKey 'the key we're going to press
KInput.dwFlags = 0 'press the key
'copy the structure into the input array 's buffer.
GInput(0).dwType = INPUT_KEYBOARD ' keyboard input
CopyMemory GInput(0).xi(0), KInput, Len(KInput)
'do the same as above, but for releasing ' the key
KInput.wVk = bKey ' the key we're going to realease
KInput.dwFlags = KEYEVENTF_KEYUP ' release the key
GInput(1).dwType = INPUT_KEYBOARD ' keyboard input
CopyMemory GInput(1).xi(0), KInput, Len(KInput)
'send the input now
Call SendInput(2, GInput(0), Len(GInput(0)))
End Sub
To simulate “H” Keystroke, just call SendKey(CByte(asc(“H”))
