[Mono-bugs] [Bug 386450] New: new Font() is not a new object ... sometimes

[bugzilla_noreply at novell.com]

https://bugzilla.novell.com/show_bug.cgi?id=386450


           Summary: new Font() is not a new object ... sometimes
           Product: Mono: Class Libraries
           Version: 1.9.0
          Platform: Other
               URL: http://limada.sourceforge.net/Limaki/
        OS/Version: Windows XP
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Windows.Forms
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: lytico at users.sourceforge.net
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---


Creating a Font-Object with new Font(...) and 
disposing this font-object 
disposes other "instances" of a font-object with same font-family, size and
style.

Example (tested on .Net 2.0: works; mono 1.9.0 on winXP: error; NOT tested
under linux):
    public class FontProblem:Form {
        TextBox editor = null;

        public void testFont(){
            // make a new Font:
            Font fontA = new Font(
                    SystemFonts.DefaultFont.Name,
                    SystemFonts.DefaultFont.Size,
                    SystemFonts.DefaultFont.Style);

            // make another new font with same name, size, style
            using (Font fontB = 
                       new Font(
                    fontA.Name,
                    fontA.Size,
                    fontA.Style)) {

                        // do something with the font:
                        editor.Font = fontB;

                        editor.Text = "testing";

                        editor.Visible = true;
                        editor.Focus();

                        Application.DoEvents();

                        editor.Visible = false;

                        // fontB is no longer in use!
                        editor.Font = fontA;
                } // fontB is disposed

            // you get the Exception here:
            editor.Visible = true;
            editor.Focus();
        }

        // stuff to have a test environment:
        Button button = null;
        public FontProblem() {
                this.SuspendLayout();
                button = new Button();
                button.Name = "button";
                button.Text = "Test Font";
                button.Click += 
                        delegate(object sender, EventArgs e) { testFont(); };
                this.Controls.Add(button);
            editor = new TextBox();
            editor.Name = "TextBox";
            editor.Location = button.Location+
                new Size(button.Width+5,editor.Location.Y);
            this.Controls.Add(editor);
                        this.ResumeLayout();
        }

        static void Main() {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new FontProblem());
        }
    }

running this program you'll get an error like this:


Unhandled Exception: System.ArgumentException: A null reference or invalid
value
 was found [GDI+ status: InvalidParameter]
at System.Drawing.GDIPlus.CheckStatus (System.Drawing.Status) [0x0009d] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\System.Drawing\System.Drawing\gdipFunctions.cs:219
at System.Drawing.Font.GetHeight (single) [0x0000f] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\System.Drawing\System.Drawing\Font.cs:678
at System.Drawing.Font.GetHeight () [0x00000] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\System.Drawing\System.Drawing\Font.cs:562
at System.Drawing.Font.get_Height () [0x00000] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\System.Drawing\System.Drawing\Font.cs:428
at (wrapper remoting-invoke-with-check) System.Drawing.Font.get_Height ()
<0x00036>
at System.Windows.Forms.LineTag.MaxHeight () [0x00000] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\LineTag.cs:560
at System.Windows.Forms.Line.RecalculateLine
(System.Drawing.Graphics,System.Windows.Forms.Document) [0x0024c] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\Line.cs:534
at System.Windows.Forms.Document.RecalculateDocument
(System.Drawing.Graphics,int,int,bool) [0x000ad] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextControl.cs:3514
at System.Windows.Forms.Document.RecalculateDocument (System.Drawing.Graphics)
[0x00000] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextControl.cs:3462
at System.Windows.Forms.Document.owner_VisibleChanged
(object,System.EventArgs)[0x00010] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextControl.cs:3597
at System.Windows.Forms.Control.OnVisibleChanged (System.EventArgs) [0x0002d]
in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\Control.cs:6447
at System.Windows.Forms.Control.SetVisibleCore (bool) [0x000f0] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\Control.cs:4944
at System.Windows.Forms.Control.set_Visible (bool) [0x0000c] in
C:\cygwin\tmp\monobuild\build\BUILD\mono-1.9\mcs\class\Managed.Windows.Forms\System.Windows.Forms\Control.cs:3372
at (wrapper remoting-invoke-with-check)
System.Windows.Forms.Control.set_Visible (bool) <0x0004b>
at MonoWinformTests.FontProblem.testFont () <0x0018e>
..


I guess there is a font-cache somethere, the new Font() gives an object out of
this cache, so I don't get a new instance (despite of new), but a new reference
on an existing object.

cheers,
lytico 
on trying to get limada.sourceforge.net/Limaki to run on mono


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