ONMESSAGE - Access Violation

[Allan]

I was getting an ACCESS VIOLATION when I closed my Window using the ONMESSAGE events.

The problem was using the same SUB as the  ONMESSAGE Main,@IDCLOSEWINDOW,&EndProgram
for the Menu Item QUIT and also for a Button CLOSE.
ONMENUPICK Main,200,&EndProgram
ONCONTROL Main, BTN_EXIT, 0, &EndProgram

I changed to a different SUB  for the Menu and Button
ONMENUPICK Main,200,&ExitProgram
ONCONTROL Main, BTN_EXIT, 0, &ExitProgram

Still had the Access Violation Messages in the Debug panel.

Worked it out that the message que was where the answer was and used a POSTMESSAGE to make it work without an Access Violation appearing in the Debug Panel.

Code Select Expand

' window using the ONMESSAGE

' ONMESSAGE Main,@IDCLOSEWINDOW,&EndProgram
' ONMENUPICK Main,200,&EndProgram
' ONMENUPICK Main,100,&Show
' ONCONTROL Main, BTN_EXIT, 0, &EndProgram

' compile in Debug Mode
' click Exit button or Quit Menu option to close window
' notice in Debug Tab the Access Violation

$MAIN

AUTODEFINE "OFF"

DECLARE IMPORT, PostMessage Alias PostMessageA(hwnd:INT, wMsg:INT, wParam:INT, lParam:INT),INT

CONST BTN_EXIT = 300
CONST WM_CLOSE = 0x10

Window Main

OPENWINDOW Main,0,0,420,275,@SIZE|@MINBOX|@MAXBOX,0,"Window OnMessage",NULL
CONTROL Main,@BUTTON,"Exit",160,20,100,24,0x50000000,BTN_EXIT

BEGINMENU Main
    MENUTITLE "&File"
    MENUITEM "&Show",0,100
    MENUITEM "&Quit",0,200
ENDMENU

CENTERWINDOW Main

' Event messages
ONMESSAGE Main,@IDCLOSEWINDOW,&EndProgram
ONMENUPICK Main,200,&ExitProgram                ' changed to ExitProgram from EndProgram
ONMENUPICK Main,100,&Show
ONCONTROL Main, BTN_EXIT, 0, &ExitProgram       ' changed to ExitProgram from EndProgram

WAITUNTIL Main = 0
END


SUB EndProgram(),INT
CLOSEWINDOW Main
RETURN 0
ENDSUB

SUB Show()
string str1

str1 = "Close Window in Debug mode"
MESSAGEBOX Main, str1, "NOTICE"
' SENDMESSAGE Main, WM_CLOSE, 0, 0          ' Sends message now
PostMessage(Main.hwnd,WM_CLOSE,0,0)       ' puts message on end of Message Que
RETURN 0
ENDSUB

SUB ExitProgram()
PostMessage(Main.hwnd,WM_CLOSE,0,0)       ' puts message on end of Message Que
RETURN 0
ENDSUB


[Ionic Wind Support Team]

Allan,
That is what the return value is for when processing messages.  Return TRUE if you close the window in response to a menu pick command, windows sends a myriad of messages when you're clicking on a menu, returning TRUE indicates you don't want the default Windows handler to process the message.

SUB ExitProgram()
   Closewindow main
   RETURN TRUE
ENDSUB

Paul.

[Allan]

Return TRUE

That is much easier to use.

Thanks