Outlook Style Groupbox Control

Introduction
This article explains very simple implementation of a outlook style groupbox. This control also supports transparent background.

Features
Following are the customizable things in this control

• Groupbox border color
• Back image or icon

Transparent background

This is achieved by using follwing code.

bool _isTransparent = false;
[Browsable(true), Category("Appearance")]
public bool IsTransparent
{
  get { return _isTransparent; }
  set
  {
    _isTransparent = value;
    if (_isTransparent == true)
    {
      this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
      this.BackColor = Color.Transparent;
    }
    Invalidate();
  }
}

Source Code (Download here)

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Windows.Forms;

namespace Owf.Controls
{
  public partial class OutlookGroupBox : Panel
  {
    [Browsable(true)]
    public new string Text
    {
      get { return base.Text; }
      set
      {
        base.Text = value;
        Invalidate();
      }
    }

    private Color _lineColor = SystemColors.Highlight;
    [Browsable(true), Category("Appearance")]
    public Color LineColor
    {
      get { return _lineColor; }
      set
      {
        _lineColor = value;
        Invalidate();
      }
    }

    private Image _image;
    [Browsable(true), Category("Appearance")]
    public Image Image
    {
      get { return _image; }
      set
      {
        if (value != null)
        {
          _image = value;
          _icon = null;
          Invalidate();
        }
      }
    }

    private Icon _icon;
    [Browsable(true), Category("Appearance")]
    public Icon Icon
    {
      get { return _icon; }
      set
      {
        if (value != null)
        {
          _icon = value;
          _image = null;
          Invalidate();
        }
      }
    }

    bool _isTransparent = false;
    [Browsable(true), Category("Appearance")]
    public bool IsTransparent
    {
      get { return _isTransparent; }
      set
      {
        _isTransparent = value;
        if (_isTransparent == true)
        {
          this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
          this.BackColor = Color.Transparent;
        }
        Invalidate();
      }
    }

    public OutlookGroupBox()
    {
      InitializeComponent();
      SetStyles();
    }

    public OutlookGroupBox(IContainer container)
    {
      container.Add(this);
      InitializeComponent();
      SetStyles();
    }

    void SetStyles()
    {
      this.SetStyle(ControlStyles.DoubleBuffer, true);
      this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
      this.SetStyle(ControlStyles.ResizeRedraw, true);
      this.SetStyle(ControlStyles.UserPaint, true);
      this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
    }

    private void OutlookGroupBox_Paint(object sender, PaintEventArgs e)
    {
      Font font = this.Font;
      SizeF size = e.Graphics.MeasureString(this.Text, font);

      e.Graphics.DrawString(this.Text, font, new SolidBrush(this.ForeColor), 1, 1);
      e.Graphics.DrawLine(new Pen(_lineColor), size.Width + 3, (size.Height + 3) / 2, 
          this.Width - 5, (size.Height + 3) / 2);

      if (_image != null)
      {
        e.Graphics.DrawImageUnscaled(_image, this.Padding.Left, this.Padding.Top);
      }
      else if (_icon != null)
      {
        e.Graphics.DrawIconUnstretched(_icon, new Rectangle(this.Padding.Left, 
           this.Padding.Top, _icon.Width, _icon.Height));
      }
    }
  }
}