subclassing

[jugador]

I am not quite sure if this is the right place to post, but I am not looking for code or specific help; this is just for discussion.
Is a concept like this actually possible? If so, what would be the advantages?

server::

Local $hCallBack = .........

Local $hGUI = GUICreate("Server", 400, 120)
GUISetState()

Do
Until GUIGetMsg() = $GUI_EVENT_CLOSE

Func __subclassing($hWnd, $iMsg, $wParam, $lParam, $iID, $pData)
    ;...........
    Return DllCall('comctl32.dll', 'lresult', 'DefSubclassProc', .....................)[0]
EndFunc

Client::

Local $hCallBack = .........

Local $hGUI = GUICreate("Client", 450, 250)

Local $idListView = GUICtrlCreateListView("Items|Column 1|Column 2", 10, 10, 430, 230, -1, $LVS_EX_DOUBLEBUFFER)
Local $hListView = GUICtrlGetHandle($idListView)
Local $hHeader = GUICtrlSendMsg($idListView, $LVM_GETHEADER, 0, 0)

For $i = 1 To 5
    GUICtrlCreateListViewItem("row" & $i & "|dataA" & $i & "|dataB" & $i, $idListView)
Next
_WinAPI_SetWindowSubclass($hHeader, $hCallBack, 2000)

GUISetState()

Do
Until GUIGetMsg() = $GUI_EVENT_CLOSE

_WinAPI_RemoveWindowSubclass($hHeader, $hCallBack, 2000)

 

Edited June 18 by jugador

[MattyD]

I wouldn't over complicate things... 

Here's a snippet of something I  was playing with at some point.  In my main script, I just include the file and call the ApplySubclass func.

#include-once
#include <WinAPI.au3>

Global $__g_hCanvasProc = DllCallbackRegister("Canvas_WndProc", "lresult", "hwnd;uint;wparam;lparam;uint_ptr;dword_ptr")
OnAutoItExitRegister("Canvas_FinalCleanup")

Func Canvas_WndProc($hWnd, $iMsg, $wParam, $lParam, $iIdSubclass, $dwRefData)
    #forceref $hWnd, $iMsg, $wParam, $lParam, $iIdSubclass, $dwRefData

    Switch $iMsg
        Case $WM_CLOSE
            Return Canvas_Close($hWnd, $iMsg, $wParam, $lParam, $iIdSubclass)
            
        ; etc...
        
        Case Else
            Return _WinAPI_DefSubclassProc($hWnd, $iMsg, $wParam, $lParam)

    EndSwitch

EndFunc   ;==>Canvas_WndProc

Func Canvas_ApplySubclass($hWnd)
    _WinAPI_SetWindowSubclass($hWnd, DllCallbackGetPtr($__g_hCanvasProc), 0)
EndFunc   ;==>Canvas_ApplySubclass

Func Canvas_Close($hWnd, $iMsg, $wParam, $lParam, $iIdSubclass)
    #forceref $hWnd, $iMsg, $wParam, $lParam
    _WinAPI_RemoveWindowSubclass($hWnd, DllCallbackGetPtr($__g_hCanvasProc), $iIdSubclass)
    Return _WinAPI_DefSubclassProc($hWnd, $iMsg, $wParam, $lParam)
EndFunc   ;==>Canvas_Close

Func Canvas_FinalCleanup()
    DllCallbackFree($__g_hCanvasProc)
EndFunc

PS. For a control, I usually remove the subclass on  $WM_DESTROY.

[jugador]

Thanks, but its just for fun, nothing serious.
It just the bug within me of doing multi-threading and multi-processing in AutoIt.

My take, doing it this way is possible. 
But how practical it is and what the advantages are, I don't know.

Edited June 18 by jugador

[MattyD]

nah, not very practical. 

Your ptrs are only valid for the process where you define it -  so you can't call your proc (or likely defsubclassproc) across process boundaries. To intercept window messages from another exe you'd probably be looking at a hook.  And if memory serves, that type of hook must be written within a dll.

Even if we were to get that all working, its going to be more efficient to deal with the messages in process

Edit: more to the last point, the underlying dispachmessage in a msg loop is synchronous -  so your "client" process is going to sit and wait for the "server" to finish. You get all the overhead without a performance gain.

Edited June 18 by MattyD

[jugador]

main problem: 
HDC, HBITMAP, HPEN, and HBRUSH are process-specific tokens.
So, GDI handles like HDC are strictly local to the host process and cannot be used cross-process.
GetDC may work, but will flicker too much and lacks synchronization.

Edit:
so to make HDC work, you have to do it from client side.... but somewhat sluggish.

Local $tRect = DllStructCreate($tagRECT)
_WinAPI_SetBkMode($hDC, 1)
_WinAPI_SetTextColor($hDC, 0xFFFFFF)

Local $hBrush = _WinAPI_CreateSolidBrush($iColor)
_WinAPI_InflateRect($tRect, -1, 0)
_WinAPI_FillRect($hDC, $tRect, $hBrush)
_WinAPI_DeleteObject($hBrush)
_WinAPI_InflateRect($tRect, -5, -2)

_WinAPI_DrawText($hDC, $text, $tRect, BitOR($DT_LEFT, $DT_NOCLIP, $DT_VCENTER, $DT_SINGLELINE))

 

Edited June 22 by jugador