OpenEuphoria

Re: Stopping onClose Event in Win32Lib

• Posted by Patrick Quist <quistnet at HOTMAIL.COM> Feb 19, 1999
• 450 views

>From:         "Cuny, David" <David.Cuny at DSS.CA.GOV>
>Subject:      Re: Stopping onClose Event in Win32Lib
>
>Ray Smith wrote:
>
>> I can use the "onClose" event to process a procedure when the
>> user clicks on the "x" but I don't know how to cancel the even
>> if the user wants to click on "Cancel" meaning I do not want to
close.
>
>Good point. I've been wondering how to implement the overriding of
default
>behaviors in Win32Lib.
>
>When Win32Lib creates a control, it grabs the control's callback (a
pointer
>to Win32 code that handles events), and stores it in window_func. Then
in
>replaces the default Win32 callback with a Euphoria callback to my
WndProc
>routine. When a control gets an action, Win32 triggers the Euphoria
callback
>code instead of the default Win32 callback. That's how Win32Lib "hooks"
into
>events.
>
>Since the Euphoria code gets run *instead* of the default window
callback,
>it's up to Win32Lib to call the callback when it's done, or Win32 can't
do
>the default action (like draw, resize, or click a control). So when the
>Euphoria code is done running, Win32Lib calls the original Win32
callback of
>the control:
>
>    -- run behavior
>    return c_func( xCallWindowProc, {   window_func[id],
>                                        hWnd,
>                                        iMsg,
>                                        wParam,
>                                        lParam } )
>
>For windows, Win32Lib runs it's own code, and then calls DefWindowProc
to
>handle the default action:
>
>    return c_func( xDefWindowProc, { myHwnd, iMsg, wParam, lParam } )
>
>What (I think) you are asking is the ability to specify that the
default
>action (for example, closing the window) *not* be called in certain
cases.
>There is currently no way to do that, but it wouldn't be difficult to
add.
>For example, I could add a routine skipDefaultAction (or some better
name)
>that would flag the default callback from running. So you could write:
>
>   function onClose_Window()
>      -- is the flag preventing the window from closing?
>      if not canClose then
>         -- cancel the default action
>         skipDefaultAction()
>      end if
>   end function
>
>and if the canClose flag was false, the window would not close
>
>Comments?
>
>Thanks.
>
>-- David Cuny
>
>

What's wrong, I use for cancelling the request of closing by :

WinMain(MainWindow)
onload_MainWindow()

That's all!

Bye,
PQ
QC

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