PureBasic Forum

; This is the hook procedure. It must be compiled to a dll.
; Every process on which this hook is installed will load
; this dll and execute the procedure.
;
; Even though you also load this dll from the program that installes
; the hook, you have to keep in mind that this code is mostly excecuted
; inside a foreign process, not the one of your program.
;
; For this example, all the code does is catch a #WM_CREATE message
; and broadcast our own message, so the original program can read
; it. Usually, whatever task needs to be done can be done right here
; inside the procedure, so that extra message is not needed.
;
Global CreateMessage.l

ProcedureDLL AttachProcess(Instance)
  CreateMessage = RegisterWindowMessage_("MyHook_Window_Created")
EndProcedure

; This is the hook procedure
; The parameters depend on what type of hook you install.
; This is a hook which is called before the window procedure of the
; process is called.
;
ProcedureDLL MyHookProcedure(nCode.l, wParam.l, *lParam.CWPSTRUCT)

  ; Just catch this one message.
  If *lParam\message = #WM_CREATE
    PostMessage_(#HWND_BROADCAST, CreateMessage, *lParam\hwnd, 0)
  EndIf

  ; This is very important to allow multiple hooks to work side by side.
  ProcedureReturn CallNextHookEx_(@MyHookProcedure(), nCode, wParam, *lParam)
EndProcedure

; This is the program that installes the hook.
; Note: it also needs to load the hook dll, even if it itself is not hooked.

; little gui stuff
Enumeration
  #GADGET_List
  #GADGET_Start
  #GADGET_Stop
EndEnumeration

#Hook_Path = "b:\test.dll" ; the hook dll
#LIBRARY_Hook = 0          ; PB id for our dll.

If OpenWindow(0, 0, 0, 400, 400, #PB_Window_SystemMenu|#PB_Window_Screencentered, "Hook example")
  If CreateGadgetList(WindowID())
    ListViewGadget(#GADGET_List, 5, 5, 390, 365)
    ButtonGadget(#GADGET_Start, 5, 375, 120, 20, "Install Hook")
    ButtonGadget(#GADGET_Stop, 130, 375, 120, 20, "Remove Hook")   
  EndIf
 
  DisableGadget(#GADGET_Stop, 1)
  CreateMessage = RegisterWindowMessage_("MyHook_Window_Created")
 
  Repeat
    Event = WaitWindowEvent()
   
    ; here we received our create message..
    ;
    If Event = CreateMessage
      hwnd = EventwParam()
      Name$ = Space(500)
      GetWindowText_(hwnd, @Name$, 500)
      AddGadgetItem(#GADGET_List, -1, "WM_CREATE: "+RSet(Hex(hwnd), 8, "0")+" -> "+Name$)
      SetGadgetState(#GADGET_List, CountGadgetItems(#GADGET_List)-1)
   
    ElseIf Event = #PB_EventCloseWindow
      Quit = 1
   
    ElseIf Event = #PB_EventGadget
      Select EventGadgetID()
     
        Case #GADGET_Start
       
          ; This code installes the hook.       
          If OpenLibrary(#LIBRARY_Hook, #Hook_Path)
            dllInstance = LibraryID(#LIBRARY_Hook)
            dllFunction = IsFunction(#LIBRARY_Hook, "MyHookProcedure")
           
            ; If you set the last parameter to a threadid, only this thread will get
            ; hooked. Like this, every thread is hooked.
            HookID = SetWindowsHookEx_(#WH_CALLWNDPROC, dllFunction, dllInstance, #NULL)
            If HookID
              DisableGadget(#GADGET_Start, 1)
              DisableGadget(#GADGET_Stop, 0)
              AddGadgetItem(#GADGET_List, -1, "=====> Hook installed")
              SetGadgetState(#GADGET_List, CountGadgetItems(#GADGET_List)-1)
            EndIf
          EndIf
       
        Case #GADGET_Stop
       
          ; This removes the hook.. quite simple.
          If HookID
            UnhookWindowsHookEx_(HookID)
            CloseLibrary(#LIBRARY_Hook)
            DisableGadget(#GADGET_Start, 0)
            DisableGadget(#GADGET_Stop, 1)
            AddGadgetItem(#GADGET_List, -1, "=====> Hook removed")
            SetGadgetState(#GADGET_List, CountGadgetItems(#GADGET_List)-1)
            HookID = 0
          EndIf
     
      EndSelect
   
    EndIf
  Until Quit
 
EndIf

; unhook if not allready done.
If HookID
  UnhookWindowsHookEx_(HookID)
  CloseLibrary(#LIBRARY_Hook)
EndIf
End

; WARNING: Running this *might* crash your PC!

Procedure WindowHook(uMsg,wParam,lParam)
  If uMsg=#HCBT_ACTIVATE
    AddGadgetItem(0,-1,Str(wParam)) ; Show window handle that just opened?
    UnhookWindowsHookEx_(hHook)
  EndIf
  ProcedureReturn #FALSE
EndProcedure

If OpenWindow(1,300,250,400,200,#PB_Window_SystemMenu,"test")
  CreateGadgetList(WindowID())
  ListViewGadget(0,0,0,400,200)
  hHook=SetWindowsHookEx_(#WH_CBT,@WindowHook(),GetModuleHandle_(0),GetCurrentThreadId_())
  Repeat : Until WaitWindowEvent()=#PB_Event_CloseWindow
EndIf

ProcedureDLL MyHookProcedure(nCode.l, wParam.l, *lParam.CWPSTRUCT)

  ; Just catch this one message.
  If *lParam\message = #WM_CREATE
 
    ; only check toplevel windows
    If GetWindowLong_(*lParam\hwnd, #GWL_STYLE) & #WS_CHILD = 0
   
      Name$ = Space(1000)
     
      ; since this dll is executed by the hooked programm, this call will
      ; return the calculator executable name
      ;
      GetModuleFileName_(0, @Name$, 1000)
      If LCase(GetFilePart(Name$)) = "calc.exe"
       
        ; get the window size and move it.
        GetWindowRect_(*lParam\hwnd, @Size.RECT)
        w = Size\right - Size\left
        h = Size\bottom - Size\top
        x = (GetSystemMetrics_(#SM_CXSCREEN)-w)/2
        y = (GetSystemMetrics_(#SM_CYSCREEN)-h)/2
        MoveWindow_(*lParam\hwnd, x, y, w, h, #False)
       
      EndIf
    EndIf   
  EndIf

  ; This is very important to allow multiple hooks to work side by side.
  ProcedureReturn CallNextHookEx_(@MyHookProcedure(), nCode, wParam, *lParam)
EndProcedure