I don't seem to understand how WM_NOTIFY works

[Valzul]

Hi everyone,

I'm relatively new to AutoIT, but I recently found myself facing the WM_NOTIFY function and don't seem to actually catch up how it does work ...

First, i've been following this guide from the Wiki : Tutorial on GUIRegisterMsg

And so i've decided to try on my own, and as an example, to catch BN_CLICKED with the WM_NOTIFY function.

Here is my actual code ( that has been created from pieces of code I gathered around the net ) :

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#include <WindowsConstants.au3>
#include <EditConstants.au3>
#include <ButtonConstants.au3>
#include <WinAPI.au3>
#include <GUIConstantsEX.au3>

 $MyGUI = GUICreate("MyGUI",200,200,200,200)
 $iBtn = GUICtrlCreateButton("MyButton",20,20,50,50)
 $iBtn2 = GUICtrlCreateButton("MyButton2",70,70,50,50)
 GUISetState(@SW_SHOW)

GUIRegisterMsg($WM_NOTIFY,"WM_NOTIFY")

 While 1
 $nMsg = GUIGetMsg()
    Switch $nMsg
        Case $GUI_EVENT_CLOSE
        Exit 
    EndSwitch
 WEnd

Func WM_NOTIFY($hWnd, $iMsg, $wParam, $lParam)
Switch _WinAPI_LoWord($wParam)
        Case $iBtn
                Switch _WinAPI_HiWord($wParam)
                        Case $BN_CLICKED
                        MsgBox(48,'$iBtn','This button was clicked !')
                        Return $GUI_RUNDEFMSG
                EndSwitch
        Case $iBtn2
                Switch _WinAPI_HiWord($wParam)
                        Case $BN_CLICKED
                        MsgBox(48,'$iBtn2','This button was clicked !')
                        Return $GUI_RUNDEFMSG
                EndSwitch
EndSwitch
Return $GUI_RUNDEFMSG
EndFunc

I only have to hover the button to trigger the WM_NOTIFY, but I'm willing to trigger it only on CLICK of these buttons.

From what I've gathered on MSDN, BN_CLICKED is recieved from WM_COMMAND message, but in this example I don't specify WM_COMMAND ... 

I've seen som WM_NOTIFY function that are using a Structure, how do I know what type of data to insert on this structure ( I can't seem to find it on MSDN for some of them ) ?

Is it possible for me to find a full documentation for real beginners about this on the WEB, or do I have to actually check every example on the WEB and adapt them to make it works like I need it to work ?

Thanks in advance for your answers,

Valzul.

[BrewManNH]

I created a script that demos how to use the windows messages to find out what control is being actioned. See the link in my signature to it, it might give you some ideas.

[Valzul]

Thanks BrewManNH !

I sure will be learning from your demo ! 

Is it possible to handle every notification code using your definition of _WM_EXTRACTOR ? : 

Local $nNotifyCode = BitShift($wParam, 16)
    Local $nID = BitAND($wParam, 0x0000FFFF)
    Local $hCtrl = $lParam
    #forceref $hWnd, $iMsg, $wParam, $lParam

Is this way of defining the function used for another purpose ? Or is it a different way to code the same functionnality as your _WM_EXTRACTOR ?  :

#forceref $hWndGUI, $MsgID, $wParam
    Local $tagNMHDR, $event, $hwndFrom, $code
    $tagNMHDR = DllStructCreate("int;int;int", $lParam);NMHDR (hwndFrom, idFrom, code)

( The example above was taken from this post of users's Vision : https://www.autoitscript.com/forum/topic/105993-listview-wm_notify/ )

Valzul.

[BrewManNH]

Theoretically you can add cases for every type of Window's message in the extractor function.

I'm not sure of the point of the struct in that code, the windows message handler already supplies the $lparam, so putting it into the struct and then retrieving it on the next line doesn't seem to make sense to me, but I'm not sure what was being done in that code.