I use the code down below to start an application and move it into a Panel on my Form. In this example I use Notepad, only as an example. Later I will use a different application.
When another application is moved in front of my Form, I can only move my Form to the foreground by clicking the title bar. If I click on the MDI child area (so the Panel where Notepad is moved into), nothing happens.
Is there a way to enable that?
Imports System.Runtime.InteropServices
Public Class Form1
Declare Auto Function SetParent Lib "user32.dll" (ByVal hWndChild As IntPtr, ByVal hWndNewParent As IntPtr) As Integer
Declare Auto Function SendMessage Lib "user32.dll" (ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim proc As Process
proc = Process.Start("notepad.exe")
proc.WaitForInputIdle()
SetParent(proc.MainWindowHandle, Me.Panel1.Handle)
SendMessage(proc.MainWindowHandle, 274, 61488, 0)
End Sub
End Class
The problem is that a hosted (re-parented) Window, when activated, doesn't cause the hosting Form to also activate, so it's brought to the foreground.
The hosted Window is not exactly a child Window and the hosting Form doesn't receive any message from it.
A possible method to bring to the foreground the Form that hosts a foreign Window, when this Window receives the focus (you click or otherwise activate it).
It uses SetWinEventHook to install a Hook that monitors changes in state of the placement of a Window (EVENT_SYSTEM_FOREGROUND).
You specify the handle of the Window of interest, (your proc.MainWindowHandle here), plus its ProcessId and ThreadId. Note that these are not the same as your app's, a call to GetWindowThreadProcessId() is required to get this information.
When you activate the foreign Window, the Hook calls the specified callback delegate (here, ForegroundChangedEventDelegate), which in turn executes the method that it points to (ForegroundStateChangedCallback)
When this method is called, it checks whether the object that caused the notification is OBJID_WINDOW and that the event is actually EVENT_SYSTEM_FOREGROUND. If that's the case, it calls SetWindowPos to bring the hosting Form to the foreground, but without activating it, so the hosted Window doesn't lose focus
Notes:
The SetWinEventHook delegate is created in the Constructor (Sub New()) of the parent Form, along with a GC SafeHandle that is used to prevent the delegate from being garbage-collected at the wrong time.
It's released in the OnHandleDestroyed() override, where also the hook proc is un-hooked
see the imports statement in the Form:
Imports [Your App Namespace].NativeMethods
this means that you have to specify the namespace of your app for the import to work as intended. In VB.NET, usually the name of the app and its main Namespace match; if your app is named, WinFormsApp1, then it's Imports WinFormsApp1.NativeMethods
SetForegroundStateChangedHook() method. That's all.I suggest using the code in Unhook Window into its original State to set the Parent (and, possibly, set it back to the original value before closing the hosting form). You can send WM_CLOSE to the Window if needed.
Imports [Your App Namespace].NativeMethods
Public Class SomeForm
Private hForegrundChangedEventHook As IntPtr
Private ReadOnly ForegrundChangedEventDelegate As WinEventDelegate
Private Shared GCForegroundStateSafetyHandle As GCHandle
Public Sub New()
InitializeComponent()
ForegrundChangedEventDelegate = New WinEventDelegate(AddressOf ForegroundStateChangedCallback)
GCForegroundStateSafetyHandle = GCHandle.Alloc(ForegrundChangedEventDelegate)
End Sub
Protected Overrides Sub OnHandleDestroyed(e As EventArgs)
GCForegroundStateSafetyHandle.Free()
UnhookWinEvent(hForegrundChangedEventHook)
MyBase.OnHandleDestroyed(e)
End Sub
Private Sub SetForegroundStateChangedHook(hWnd As IntPtr)
Dim processId As UInteger
Dim targetThreadId = GetWindowThread(hWnd, processId)
hForegrundChangedEventHook = WinEventHookOne(SWEH_Events.EVENT_SYSTEM_FOREGROUND, ForegrundChangedEventDelegate, processId, targetThreadId)
End Sub
Friend Sub ForegroundStateChangedCallback(hWinEventHook As IntPtr, eventType As SWEH_Events, hWnd As IntPtr, idObject As SWEH_ObjectId, idChild As Long, dwEventThread As UInteger, dwmsEventTime As UInteger)
If idObject = SWEH_ObjectId.OBJID_WINDOW AndAlso eventType = SWEH_Events.EVENT_SYSTEM_FOREGROUND Then
Dim flags = SWP_Flags.SWP_ASYNCWINDOWPOS Or SWP_Flags.SWP_NOACTIVATE Or SWP_Flags.SWP_NOSIZE Or SWP_Flags.SWP_NOMOVE
SetWindowPos(Handle, IntPtr.Zero, 0, 0, 0, 0, flags)
End If
End Sub
End Class
NativeMethods class
Add this class to the Project and import in your Form as described
Imports System.Runtime.InteropServices
Public Class NativeMethods
<DllImport("user32.dll", SetLastError:=True)>
Friend Shared Function GetWindowThreadProcessId(hWnd As IntPtr, ByRef lpdwProcessId As UInteger) As UInteger
End Function
<DllImport("user32.dll", SetLastError:=True)>
Friend Shared Function SetWindowPos(hWnd As IntPtr, hWndInsertAfter As IntPtr, x As Integer, y As Integer, cx As Integer, cy As Integer, uFlags As SWP_Flags) As Boolean
End Function
Friend Delegate Sub WinEventDelegate(
hWinEventHook As IntPtr,
eventType As SWEH_Events,
hwnd As IntPtr, idObject As SWEH_ObjectId,
idChild As Long,
dwEventThread As UInteger,
dwmsEventTime As UInteger)
<DllImport("user32.dll", SetLastError:=False)>
Friend Shared Function SetWinEventHook(
eventMin As SWEH_Events,
eventMax As SWEH_Events,
hmodWinEventProc As IntPtr,
lpfnWinEventProc As WinEventDelegate,
idProcess As UInteger,
idThread As UInteger,
dwFlags As SWEH_dwFlags) As IntPtr
End Function
<DllImport("user32.dll", SetLastError:=False)>
Friend Shared Function UnhookWinEvent(hWinEventHook As IntPtr) As Boolean
End Function
Friend Shared WinEventHookInternalFlags As SWEH_dwFlags =
SWEH_dwFlags.WINEVENT_OUTOFCONTEXT Or SWEH_dwFlags.WINEVENT_SKIPOWNPROCESS
Friend Shared Function WinEventHookOne(evt As SWEH_Events, weDelegate As WinEventDelegate, idProcess As UInteger, idThread As UInteger) As IntPtr
Return SetWinEventHook(evt, evt, IntPtr.Zero, weDelegate, idProcess, idThread, WinEventHookInternalFlags)
End Function
Friend Shared Function GetWindowThread(hWnd As IntPtr, ByRef processID As UInteger) As UInteger
processID = 0
Return GetWindowThreadProcessId(hWnd, processID)
End Function
' SetWinEventHook Events
Friend Enum SWEH_Events As UInteger
EVENT_MIN = &H1
EVENT_MAX = &H7FFFFFFF
EVENT_SYSTEM_SOUND = &H1
EVENT_SYSTEM_ALERT = &H2
EVENT_SYSTEM_FOREGROUND = &H3
EVENT_SYSTEM_MENUSTART = &H4
EVENT_SYSTEM_MENUEND = &H5
EVENT_SYSTEM_MENUPOPUPSTART = &H6
EVENT_SYSTEM_MENUPOPUPEND = &H7
EVENT_SYSTEM_CAPTURESTART = &H8
EVENT_SYSTEM_CAPTUREEND = &H9
EVENT_SYSTEM_MOVESIZESTART = &HA
EVENT_SYSTEM_MOVESIZEEND = &HB
EVENT_SYSTEM_CONTEXTHELPSTART = &HC
EVENT_SYSTEM_CONTEXTHELPEND = &HD
EVENT_SYSTEM_DRAGDROPSTART = &HE
EVENT_SYSTEM_DRAGDROPEND = &HF
EVENT_SYSTEM_DIALOGSTART = &H10
EVENT_SYSTEM_DIALOGEND = &H11
EVENT_SYSTEM_SCROLLINGSTART = &H12
EVENT_SYSTEM_SCROLLINGEND = &H13
EVENT_SYSTEM_SWITCHSTART = &H14
EVENT_SYSTEM_SWITCHEND = &H15
EVENT_SYSTEM_MINIMIZESTART = &H16
EVENT_SYSTEM_MINIMIZEEND = &H17
EVENT_SYSTEM_DESKTOPSWITCH = &H20
EVENT_SYSTEM_END = &HFF
EVENT_OEM_DEFINED_START = &H101
EVENT_OEM_DEFINED_END = &H1FF
EVENT_UIA_EVENTID_START = &H4E00
EVENT_UIA_EVENTID_END = &H4EFF
EVENT_UIA_PROPID_START = &H7500
EVENT_UIA_PROPID_END = &H75FF
EVENT_CONSOLE_CARET = &H4001
EVENT_CONSOLE_UPDATE_REGION = &H4002
EVENT_CONSOLE_UPDATE_SIMPLE = &H4003
EVENT_CONSOLE_UPDATE_SCROLL = &H4004
EVENT_CONSOLE_LAYOUT = &H4005
EVENT_CONSOLE_START_APPLICATION = &H4006
EVENT_CONSOLE_END_APPLICATION = &H4007
EVENT_CONSOLE_END = &H40FF
EVENT_OBJECT_CREATE = &H8000
EVENT_OBJECT_DESTROY = &H8001
EVENT_OBJECT_SHOW = &H8002
EVENT_OBJECT_HIDE = &H8003
EVENT_OBJECT_REORDER = &H8004
EVENT_OBJECT_FOCUS = &H8005
EVENT_OBJECT_SELECTION = &H8006
EVENT_OBJECT_SELECTIONADD = &H8007
EVENT_OBJECT_SELECTIONREMOVE = &H8008
EVENT_OBJECT_SELECTIONWITHIN = &H8009
EVENT_OBJECT_STATECHANGE = &H800A
EVENT_OBJECT_LOCATIONCHANGE = &H800B
EVENT_OBJECT_NAMECHANGE = &H800C
EVENT_OBJECT_DESCRIPTIONCHANGE = &H800D
EVENT_OBJECT_VALUECHANGE = &H800E
EVENT_OBJECT_PARENTCHANGE = &H800F
EVENT_OBJECT_HELPCHANGE = &H8010
EVENT_OBJECT_DEFACTIONCHANGE = &H8011
EVENT_OBJECT_ACCELERATORCHANGE = &H8012
EVENT_OBJECT_INVOKED = &H8013
EVENT_OBJECT_TEXTSELECTIONCHANGED = &H8014
EVENT_OBJECT_CONTENTSCROLLED = &H8015
EVENT_SYSTEM_ARRANGMENTPREVIEW = &H8016
EVENT_OBJECT_END = &H80FF
EVENT_AIA_START = &HA000
EVENT_AIA_END = &HAFFF
End Enum
' SetWinEventHook Window Objects
Friend Enum SWEH_ObjectId As Long
OBJID_WINDOW = &H0
OBJID_SYSMENU = &HFFFFFFFFUI
OBJID_TITLEBAR = &HFFFFFFFEUI
OBJID_MENU = &HFFFFFFFDUI
OBJID_CLIENT = &HFFFFFFFCUI
OBJID_VSCROLL = &HFFFFFFFBUI
OBJID_HSCROLL = &HFFFFFFFAUI
OBJID_SIZEGRIP = &HFFFFFFF9UI
OBJID_CARET = &HFFFFFFF8UI
OBJID_CURSOR = &HFFFFFFF7UI
OBJID_ALERT = &HFFFFFFF6UI
OBJID_SOUND = &HFFFFFFF5UI
OBJID_QUERYCLASSNAMEIDX = &HFFFFFFF4UI
OBJID_NATIVEOM = &HFFFFFFF0UI
End Enum
' WinEventDelegate flags
Friend Enum SWEH_dwFlags As UInteger
WINEVENT_OUTOFCONTEXT = &H0 ' Events are ASYNC - No dll needed
WINEVENT_SKIPOWNTHREAD = &H1 ' Don't call back for events on installer's thread
WINEVENT_SKIPOWNPROCESS = &H2 ' Don't call back for events on installer's process
WINEVENT_INCONTEXT = &H4 ' Events are SYNC, this causes your dll to be injected into every process
End Enum
' SetWindowPos flags
<Flags>
Public Enum SWP_Flags As UInteger
SWP_NOSIZE = &H1
SWP_NOMOVE = &H2
SWP_NOZORDER = &H4
SWP_NOREDRAW = &H8
SWP_NOACTIVATE = &H10
SWP_DRAWFRAME = &H20
SWP_FRAMECHANGED = &H20
SWP_SHOWWINDOW = &H40
SWP_HIDEWINDOW = &H80
SWP_NOCOPYBITS = &H100
SWP_NOOWNERZORDER = &H200
SWP_NOREPOSITION = &H200
SWP_NOSENDCHANGING = &H400
SWP_NOCLIENTSIZE = &H800
SWP_NOCLIENTMOVE = &H1000
SWP_DEFERERASE = &H2000
SWP_ASYNCWINDOWPOS = &H4000
End Enum
End Class