Issue with close button in a 2d gaming window.

[Kane Hart]

Hello building a small game here and was having issues making a proper close button for in game windows.. I will post a chunk of code and maybe you can fix my issue..

        Case MailboxWindow
            With GameWindow.Mailbox
                Engine_Render_Grh .SkinGrh, .Screen.X, .Screen.Y, 0, 1, True, GUIColorValue, GUIColorValue, GUIColorValue, GUIColorValue
                Engine_Render_Text Font_Default, MailboxListBuffer, .Screen.X + .List.X, .Screen.Y + .List.Y, -1
                Engine_Render_Text Font_Default, "Read", .Screen.X + .ReadLbl.X, .Screen.Y + .ReadLbl.Y, -1
                Engine_Render_Text Font_Default, "Write", .Screen.X + .WriteLbl.X, .Screen.Y + .WriteLbl.Y, -1
                Engine_Render_Text Font_Default, "Delete", .Screen.X + .DeleteLbl.X, .Screen.Y + .DeleteLbl.Y, -1
                If SelMessage > 0 Then Engine_Render_Rectangle .Screen.X + .List.X, .Screen.Y + .List.Y + ((SelMessage - 1) * Font_Default.CharHeight), .List.Width, Font_Default.CharHeight, 1, 1, 1, 1, 1, 1, 0, 0, 2097217280, 2097217280, 2097217280, 2097217280, , False   'ARGB: 125/0/255/0
                    If Engine_Collision_Rect(MousePos.X, MousePos.Y, 1, 1, .Screen.X + 325, .Screen.Y + 5, 10, 17) Then
        If MouseLeftDown > 0 Then
            ShowGameWindow(LastClickedWindow) = 0
            LastClickedWindow = 0
            Exit Sub
        End If
    End If
            End With

Now this is what I added extra in that is in the above code...

  If Engine_Collision_Rect(MousePos.X, MousePos.Y, 1, 1, .Screen.X + 325, .Screen.Y + 5, 10, 17) Then
        If MouseLeftDown > 0 Then
            ShowGameWindow(LastClickedWindow) = 0
            LastClickedWindow = 0
            Exit Sub
        End If
    End If

This where I have issues.. It works fine closes no problem.. But when I click somewhere on the screen and hold down the mouse button right to this X in this window in the main game window it crashes...

So I get a error 9 and debugs goes to this:

LastClickedWindow = 0

I am a n99b and learning.. If you can give me a snip of code to try or know how to fix the issue that would be great..

[Jabber]

To stop the program you should use "END" or "Unload Me"

You could also use the ESC to end game.

        If MouseLeftDown = True Then
           Unload me        ' or END

End If

Unless you are just trying to stop the game and and show results then you should use a Boolean to pause the game loop.

Are you using a Timer or game Loop?

.

[Milk]

Jabber, did you say use End.
End is not considered a good way to stop a program it's brutal and can lead to memory leaks (akin to ending a process with task manager). Unload is much better.

[Hack]

Moved To Games Programming

[Jabber]

Jabber, did you say use End.
End is not considered a good way to stop a program it's brutal and can lead to memory leaks (akin to ending a process with task manager). Unload is much better.

OK. I will remember that but in many DX game examples they set everything to nothing and then often use END instead of "unload me."

.

[si_the_geek]

In that case, I'd recommend that you don't trust the other parts of the examples, and find a better source instead.

If somebody thinks that End is perfectly fine, the chances are that they don't have much experience - and so in other parts of the code are likely to have made errors and/or done things in inappropriate ways.

If they don't think it is fine, but have used it without saying so (such as a brief comment on that line to say "use a valid method instead"), what else have they not bothered to tell you?


For an explanation (and example code) for how you should be closing a form/program (part of which includes "Unload Me"), see the article How should I close my form/program/class? from our Classic VB FAQs (in the FAQ forum, which is shown near the top of our home page)

[Jabber]

Sub RestoreWindowsGUI()

'When you bail out of DX7 you must destroy your surfaces or they remain in Sys_Memory
ReDim AutoZ_Sprite(0) As DirectDrawSurface7: Set AutoZ_Sprite(0) = Nothing
ReDim StaticB(0) As DirectDrawSurface7: Set StaticB(0) = Nothing

'clearing other DX7 sufaces
Set StaticC = Nothing: Set StaticD = Nothing: Set StaticE = Nothing: Set Primary = Nothing: Set BackBuffer = Nothing

'End the MainLoop Bool
LoopUntilWeDrop = False

'RESTORING DISPLAY MODE
    Call d7.RestoreDisplayMode
    Call d7.SetCooperativeLevel(AutoZ_Order.hWnd, DDSCL_NORMAL)
    
    End 'WE'RE OUTTA' HERE
End Sub

si_the_geek, So you think Johnathan Drake And Jack Hoxley don't know what they are doing?

.

[Milk]

It might well be that they do know what they are doing, they have kept track of all the objects, been very careful to ensure that everything is properly dereferenced. In this case End probably tidies things up quite nicely, it's unnecessary, but it won't cause an unseen problem.

The problem arises when a less experienced programmer upon reading that code learns that End is how to terminate a program, but does not learn that they might have to clean up a bit first, and does not learn that the unload / queryunload events are bypassed. They could be leaking memory never realise it.

The End statement never has to be used, it can always be avoided.

[si_the_geek]

In addition to what Milk posted, the use of : to join multiple lines is debatable at the best of times (as it generally makes the code harder to read), and not really apt in examples/tutorials - especially when it is used to join several almost unrelated items ("other DX7 sufaces").

Based on the comments to go with it, some of the code does not seem right:

'When you bail out of DX7 you must destroy your surfaces or they remain in Sys_Memory
ReDim AutoZ_Sprite(0) As DirectDrawSurface7: Set AutoZ_Sprite(0) = Nothing

To me it sounds as if you should be doing something more than setting them to Nothing, or perhaps set all elements to Nothing. If the array is initially defined without a size (which it needs to be in order to ReDim), this code is not ideal anyway - using just Erase would be better (which sets all elements to Nothing, and resets the array to have no elements at all).


There is also the room for serious error, depending on how the rest of the program is structured. There is code for "End the MainLoop Bool", but it is run after the surfaces have been destroyed. If there is an attempt to use them, some kind of error will occur (I can't remember DX well enough to know how bad that would be).


I am by no means saying that they don't know what they are doing with DX - but they haven't presented things as well as they probably should have (see my previous post), and I suspect there are better articles to learn from.