Add a badge to a C# winforms control

Question

When writing in CSS I can add a class of \"badge\" and get what I want. A small number near a button or tab with some styling to it, to show that this control has pending in

Answer 1

And here is a way with a static Adorner class, very quick and rather dirty..

It can add a Label to many controls and it includes a click action, dynamic text and has code to remove the Label.

Adding a Badge to a Button takes one line:

    public Form1()
    {
        InitializeComponent();
        // adorn one Button with a Badge Label:
        Adorner.AddBadgeTo(button1, "123");
        // if you want to you can add a click action:
        Adorner.SetClickAction(button1, dobidoo);
    }

    // a test action
    void dobidoo(Control ctl)
    {
        Console.WriteLine("You have clicked on :" + ctl.Text);
    }

Here is the Adorner class:

static class Adorner
{
    private static List controls = new List();

    static public bool AddBadgeTo(Control ctl, string Text)
    {
        if (controls.Contains(ctl)) return false;

        Badge badge = new Badge();
        badge.AutoSize = true;
        badge.Text = Text;
        badge.BackColor = Color.Transparent;
        controls.Add(ctl);
        ctl.Controls.Add(badge);
        SetPosition(badge, ctl);

        return true;
    }

    static public bool RemoveBadgeFrom(Control ctl)
    {
        Badge badge = GetBadge(ctl);
        if (badge != null)
        {
            ctl.Controls.Remove(badge);
            controls.Remove(ctl);
            return true;
        }
        else return false;
    }

    static public void SetBadgeText(Control ctl, string newText)
    {
        Badge badge = GetBadge(ctl);
        if (badge != null) 
        {
                badge.Text = newText;
                SetPosition(badge, ctl);
        }
    }

    static public string GetBadgeText(Control ctl)
    {
        Badge badge = GetBadge(ctl);
        if (badge != null) return badge.Text;
        return "";
    }

    static private void SetPosition(Badge badge, Control ctl)
    {
       badge.Location = new Point(ctl.Width  - badge.Width - 5, 
                                  ctl.Height - badge.Height - 5);
    }

    static public void SetClickAction(Control ctl, Action action)
    {
        Badge badge = GetBadge(ctl);
        if (badge != null)  badge.ClickEvent = action;
    }

    static Badge GetBadge(Control ctl)
    {
        for (int c = 0; c < ctl.Controls.Count; c++)
            if (ctl.Controls[c] is Badge) return ctl.Controls[c] as Badge;
        return null;
    }


    class Badge : Label
    {
        Color BackColor = Color.SkyBlue;
        Color ForeColor = Color.White;
        Font font = new Font("Sans Serif", 8f);

        public Action ClickEvent;

        public Badge()   {}

        protected override void OnPaint(PaintEventArgs e)
        {
            e.Graphics.FillEllipse(new SolidBrush(BackColor), this.ClientRectangle);
            e.Graphics.DrawString(Text, font, new SolidBrush(ForeColor), 3, 1);
        }

        protected override void OnClick(EventArgs e)
        {
            ClickEvent(this);
        }

    }
}

Note that while you can add it to most controls, not all work as well as a Button. A TabControl is rather hard to adorn as its Tabs really are not Controls but just painted areas, so just like adding a 'close X' to it you would have to user draw the badges of all TabPages..