[RESOLVED] Disposing a global Font variable - keeping my code clean ;)

[Zeljko]

I have declared Fonts at class level to use it through my methods in that form. Form 'frmA' is shown with ShowDialog and when it closes or stops using fonts I'd like to properly dispose fonts.
When I run code analysis FxCop it complaints with:
CA2213 : Microsoft.Usage : 'frmA' contains field 'frmA.Font1' that is of IDisposable type: 'Font'. Change the Dispose method on 'frmA' to call Dispose or Close on this field...
How to properly dispose globally declared fonts so that is "by the rules" and FxCop does not complain any more?
How to 'Change the Dispose method on 'frmA' to call Dispose'?

Option Strict On
Public Class frmA
   Dim Font1 As System.Drawing.Font   
   Dim Font2 As System.Drawing.Font  
   Dim Font3 As System.Drawing.Font 
 
   Private Sub frmA_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
      'Do something on load
      Start()   'cals method Start that will call all other methods...
   End Sub
 
   Private Sub Start()
    Try
      Font1 = New Font("Arial", 10, FontStyle.Regular)
      Font2 = New Font(Font1.Name, 12, FontStyle.Underline)
      Font3 = New Font(Font1.Name, 14, FontStyle.Bold)
      One()
      Two()
    Finally   '==>> this is how disposing is now done: in Finally...
      Font1.Dispose()
      Font2.Dispose()
      Font3.Dispose()
    End Try
   End Sub
 
   Private Sub One()
      'draw something with above fonts...
   End Sub
 
   Private Sub Two()
      'draw something with above fonts...
   End Sub
End Class

Thank for any help...
(.NET Framework 2, VS 2008, Win XP)

[techgnome]

Don't declare your font variables at the class level... there's no need for that ... scope them to the start sub... if you need them in the One & Two subs... pass the ones you need in... there really isn't a need for class level variables that are only used in a short portion of the code for a limited time.

-tg

[Zeljko]

How can I declare a Font in Start sub and then use it in other methods (one, two...)?

tg:"there really isn't a need for class level variables that are only used in a short portion of the code for a limited time"
Methods One, Two...etc are not short by any means. That is here only to show my situation in short
I have approximately 10 methods One,Two, Three...Ten and each method having ~1000+ lines of code. In time they will definitely expand so I need a system where I can control all of my fonts from one place, withe easiness.

tg:"there really isn't a need for class level variables that are only used in a short portion of the code for a limited time"
This methods (One,Two...) are drawing to one surface and they are constantly refreshed (by invalidating) to redraw surface when conditions (calculations) changes. So it can be short time but usually is longer time.

[techgnome]

How can I declare a Font in Start sub and then use it in other methods (one, two...)?

What did I say? "pass the ones you need in" .. pass them in using parameters.

tg:"there really isn't a need for class level variables that are only used in a short portion of the code for a limited time"
Methods One, Two...etc are not short by any means. That is here only to show my situation in short
I have approximately 10 methods One,Two, Three...Ten and each method having ~1000+ lines of code. In time they will definitely expand so I need a system where I can control all of my fonts from one place, withe easiness.

I don't mean short as in lines of code... I meant it in terms of the application as as whole... the only time you're using them is when the Start sub runs... the fact that Start calls One and Two and they are thousands of lines long is irrelevant... it's still withing the confines of the Start sub.

tg:"there really isn't a need for class level variables that are only used in a short portion of the code for a limited time"
This methods (One,Two...) are drawing to one surface and they are constantly refreshed (by invalidating) to redraw surface when conditions (calculations) changes. So it can be short time but usually is longer time.

Again, I said LIMITED time... not short.... not the same thing... see my previous comment.


The other solution is to not create your font in Start.... but do it as part of their declaration. Since they don't really change, I don't see a reason to do it any other way.

   Dim Font1 As System.Drawing.Font = New Font("Arial", 10, FontStyle.Regular)
   Dim Font2 As System.Drawing.Font = New Font(Font1.Name, 12, FontStyle.Underline)
   Dim Font3 As System.Drawing.Font = New Font(Font1.Name, 14, FontStyle.Bold)

Change Start:

      One()
      Two()
'There's no point now for a Try ... since we're not going to use the Finally and you aren't Catching any exceptions...

Now in the Disposed event...

    Private Sub FrmA_Disposed(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Disposed
        Font1.Dispose()
        Font2.Dispose()
        Font3.Dispose()

    End Sub

-tg

[SJWhiteley]

You need to implement the IDisposable method for your class.

When you press the enter key after typing Implements IDisposable, several routines will be added (two). Dispose of your fonts in the dispose method.

Of course, every object which contains this object will need to call the dispose method.

Edit: eh, it looks like your 'object' is a form. If these are global fonts then you could create a shared class (or module) which creates the fonts at application startup and destroys/disposes them at shutdown.

[Zeljko]

After reading all suggestions, I think I will stick with current version with minor changes:
- assign fonts in frmA_Load event
- dispose fonts in frmA_Closing event

Fonts are all in one place for easy control, I hope they all correctly disposed, FxCop still complains, so it is still not what I wanna achieve but hey, I can get always clearer code.
Thanks all for helping...

[jmcilhinney]

Putting everything in one place is bad design. Everything should exist ONLY where it's needed. You should do as tg said. Really, how can someone with 360 posts have to ask how to declare a variable and pass an argument to a method? You know what to do because you have already declared variables and passed arguments before. You're just trying to read too much into something that is very simple. Just do EXACTLY what was posted, e.g.

Private Sub Start()
    Dim f1 As New Font(FontFamily.GenericSansSerif, 10)
    Dim f2 As New Font(FontFamily.GenericSerif, 12)
 
    Me.One(f1)
    Me.Two(f2)
 
    f1.Dispose()
    f2.Dispose()
End Sub
 
Private Sub One(ByVal f As Font)
    'Use f here.
End Sub
 
Private Sub Two(ByVal f As Font)
    'Use f here.
End Sub

[Zeljko]

You should do as tg said

I know and I will

Really, how can someone with 360 posts have to ask how to declare a variable and pass an argument to a method?

I was (over)thinking it

You're just trying to read too much into something that is very simple.

You got that right in the middle!