问题
I want to make a program in vb.NET 2008 which will listen keyboard in background, i.e. even though the application is minimized (globally). If a specific key is been pressed by user, it should keep firing 2 other keys at regular given time intervals until the user presses that specific key again.
How can this be done in vb.NET 2008?
回答1:
Source : Here
Usage: To create the hook
Private WithEvents kbHook As New KeyboardHook
Then each event can be handled:
Private Sub kbHook_KeyDown(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyDown
Debug.WriteLine(Key.ToString)
End Sub
Private Sub kbHook_KeyUp(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyUp
Debug.WriteLine(Key)
End Sub
Keyboard Hook Class :
Imports System.Runtime.InteropServices
Public Class KeyboardHook
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)> _
Private Overloads Shared Function SetWindowsHookEx(ByVal idHook As Integer, ByVal HookProc As KBDLLHookProc, ByVal hInstance As IntPtr, ByVal wParam As Integer) As Integer
End Function
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)> _
Private Overloads Shared Function CallNextHookEx(ByVal idHook As Integer, ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
End Function
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)> _
Private Overloads Shared Function UnhookWindowsHookEx(ByVal idHook As Integer) As Boolean
End Function
<StructLayout(LayoutKind.Sequential)> _
Private Structure KBDLLHOOKSTRUCT
Public vkCode As UInt32
Public scanCode As UInt32
Public flags As KBDLLHOOKSTRUCTFlags
Public time As UInt32
Public dwExtraInfo As UIntPtr
End Structure
<Flags()> _
Private Enum KBDLLHOOKSTRUCTFlags As UInt32
LLKHF_EXTENDED = &H1
LLKHF_INJECTED = &H10
LLKHF_ALTDOWN = &H20
LLKHF_UP = &H80
End Enum
Public Shared Event KeyDown(ByVal Key As Keys)
Public Shared Event KeyUp(ByVal Key As Keys)
Private Const WH_KEYBOARD_LL As Integer = 13
Private Const HC_ACTION As Integer = 0
Private Const WM_KEYDOWN = &H100
Private Const WM_KEYUP = &H101
Private Const WM_SYSKEYDOWN = &H104
Private Const WM_SYSKEYUP = &H105
Private Delegate Function KBDLLHookProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
Private KBDLLHookProcDelegate As KBDLLHookProc = New KBDLLHookProc(AddressOf KeyboardProc)
Private HHookID As IntPtr = IntPtr.Zero
Private Function KeyboardProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
If (nCode = HC_ACTION) Then
Dim struct As KBDLLHOOKSTRUCT
Select Case wParam
Case WM_KEYDOWN, WM_SYSKEYDOWN
RaiseEvent KeyDown(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
Case WM_KEYUP, WM_SYSKEYUP
RaiseEvent KeyUp(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
End Select
End If
Return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam)
End Function
Public Sub New()
HHookID = SetWindowsHookEx(WH_KEYBOARD_LL, KBDLLHookProcDelegate, System.Runtime.InteropServices.Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly.GetModules()(0)).ToInt32, 0)
If HHookID = IntPtr.Zero Then
Throw New Exception("Could not set keyboard hook")
End If
End Sub
Protected Overrides Sub Finalize()
If Not HHookID = IntPtr.Zero Then
UnhookWindowsHookEx(HHookID)
End If
MyBase.Finalize()
End Sub
End Class
回答2:
If you use KeyboardHook class, make sure you have to build your program before using. With regards to the question for a specific key, you can trigger it in KeyDown or KeyUp event. But before that, you have to use sendkeys to send keys to active window.
SendKeys.Send("L") 'Sends letter L to active window.
Then you can do the following code; below checks if letter "a" is being pressed.
Private Sub kbHook_KeyDown(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyDown
Debug.WriteLine(Key.ToString)
if Key.ToString() = "a" then
'trigger your sendkeys
end if
End Sub
To trigger a specific key like a switch button, just declare a boolean variable to check if the button is switched or not. You can declare it globally:
Dim switch as boolean = false
Just update the area where you set a condition to check the letter pressed. It will look like below:
if Key.ToString() = "a" then
if switch = false then
switch = true
'trigger send keys
else
switch = false
'deactivate send keys
end if
end if
To have a specific time in sending keys, use timer. I hope it helps.
来源:https://stackoverflow.com/questions/15038413/how-to-listen-keyboard-in-background-and-fire-keystrokes-on-demand