Setting the right font for a Windows Forms application

If you create a new form in Visual Studio, the default font will always be "Microsoft Sans Serif" although you should use a font that depends on the Windows version you are running on. For Windows 2000, XP, Server 2003 you should use "Tahoma" for Vista and above it should be "Segoe UI". In any case, do not use "MS Sans Serif".

Unfortunately, there is no simple property available so the form uses the correct font automatically. Benjamin Hollis has a blog entry about this problem already and his code is quite simple and works quite well.

It just does not take into account if a form contains other, specialized fonts or if the fonts used have special styles (Underlined, Italics etc.) applied. I have tweaked his code a little bit.. ähm.. a lot actually and this is the result: FormFontFixer.

UPDATE: The code is now licensed under a BSD license (see below)

//Original idea and code (3 lines :-) by Benjamin Hollis: http://brh.numbera.com/blog/index.php/2007/04/11/setting-the-correct-default-font-in-net-windows-forms-apps/
//Copyright (C) TeX HeX of Xteq Systems: http://texhex.blogspot.com/ and http://www.texhex.info/
public static class FormFontFixer
{
//This list contains the fonts we want to replace.
static readonly List<string> FontReplaceList
         = new List<string>( new string[] { "Microsoft Sans Serif", "Tahoma" } );


static Font _DefaultFont;
static bool _CanFixFonts;


static FormFontFixer()
{
   //Basically the font name we want to use should be easy to choose by using the SystemFonts class. However, this class
   //is hard-coded (!!) and doesn't seem to work right. On XP, it will mostly return "Microsoft Sans Serif" except
   //for the DialogFont property (=Tahoma) but on Vista, this class will return "Tahoma" instead of "SegoiUI" for this property!

   //Therefore we will do the following: If we are running on a OS below XP, we will exit because the only font available
   //will be MS Sans Serif. On XP, we gonna use "Tahoma", and any other OS we will use the value of the MessageBoxFont
   //property because this seems to be set correctly on Vista an above.

   if (Environment.OSVersion.Platform==PlatformID.Win32Windows)
   {
       //95, 98 and other crap
       _CanFixFonts = false;
       return;
   }

   if (Environment.OSVersion.Version.Major < 5)
   {
       //Windows NT
       _CanFixFonts = false;
       return;
   }

   if (Environment.OSVersion.Version.Major < 6)
   {
       //Windows 2000 (5.0), Windows XP (5.1), Windows Server 2003 and XP Pro x64 Edtion v2003 (5.2)
       _CanFixFonts = true;
       _DefaultFont = SystemFonts.DialogFont; //Tahoma hopefully
   }
   else
   {
       //Vista and above
       _CanFixFonts = true;
       _DefaultFont = SystemFonts.MessageBoxFont; //should be SegoiUI
   }
}

public static void Fix(Form form)
{
   //If we can't fix the font, exit
   if (_CanFixFonts == false)
   {
       return;
   }


   //Now start with the real work...
   foreach (Control c in form.Controls)
   {
       //only replace fonts that use one the "system fonts" we have declared
       if (FontReplaceList.IndexOf(c.Font.Name) > -1)
       {                  
           //Now check the size, when the size is 9 or below it's the default font size and we do not keep the size since
           //SegoiUI has a complete different spacing (and thus size) than MS SansS or Tahoma.
          
           //Also check if there are any styles applied on the font (e.g. Italic) which we need to apply to the new
           //font as well.

           bool bUseDefaultSize = true;
           bool bUseDefaultStyle = true;

           //is this a special size?
           if ((c.Font.Size <= 8) || (c.Font.Size >= 9))
           {
               bUseDefaultSize = false;
           }

           //are any special styles (bold, italic etc.) applied to this font?
           if ( (c.Font.Italic == true) ||
                (c.Font.Strikeout == true) ||
                (c.Font.Underline == true) ||
                (c.Font.Bold == true))
           {
               bUseDefaultStyle = false;
           }

           //if everything is set to defaults, we can use our prepared font right away
           if ((bUseDefaultSize == true) && (bUseDefaultStyle == true))
           {
               c.Font = _DefaultFont;
           }
           else
           {
               //There are non default properties set so
               //there is some work we need to do...

                                      
               //Restrive custom font style
               FontStyle Style = FontStyle.Regular;                       
               if (bUseDefaultStyle == false)
               {
                   if (c.Font.Italic) {                           
                        Style = Style | FontStyle.Italic;
                   }
                   if (c.Font.Strikeout) {
                        Style = Style | FontStyle.Strikeout;
                   }
                   if (c.Font.Underline) {
                       Style = Style | FontStyle.Underline;
                   }
                   if (c.Font.Bold){
                       Style = Style | FontStyle.Bold;
                   }
               }

               //Retrive custom size
               float fFontSize = _DefaultFont.SizeInPoints;
               if (bUseDefaultSize == false)
               {
                   fFontSize = c.Font.SizeInPoints;

               }

               //Finally apply this font...
               Font font = new Font(_DefaultFont.Name, fFontSize, Style, GraphicsUnit.Point);
               c.Font = font;

           }                
       }
   }

}
}


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