Here is an example which I developed for same purpose ... hope its useful
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text.RegularExpressions;
using System.Windows.Forms;
using System.Diagnostics;
namespace CustomControls
{
#region CustomCombo
/// <summary>
/// Summary description for ComboBox.
/// </summary>
public class CustomCombo : System.Windows.Forms.ComboBox
{
#region Designer Section
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components = null;
#region Default Constructor
public CustomCombo()
{
// This call is required by the Windows.Forms Form Designer.
InitializeComponent();
// TODO: Add any initialization after the InitializeComponent call
}
#endregion
#region Dispose
/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if(components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#endregion
#endregion
#region Component Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
//
// ComboBox
//
this.Name = "ComboBox";
}
#endregion
#region User Defined variables
/// <summary>
/// Tooltip member to show the tooltip for the combo when the text in the
combo spans out of the
/// visible area of the control
/// </summary>
private ToolTip toolTipCombo = new ToolTip();
#endregion
#region Properties
#endregion
#region ResetControl
public void ResetControl()
{
if(!this.Text.Equals(""))
{
this.Text = "";
}
this.SelectedIndex = -1;
}
#endregion
#endregion
#region Events
#region OnGotFocus
protected override void OnGotFocus(EventArgs e)
{
try
{
if(this.TabIndex == 0)
{
return;
}
foreach( Control ctrl in ((Form)this.TopLevelControl).Controls)
{
if(ctrl.GetType() == typeof(StatusBar))
{
foreach( StatusBarPanel inCtrl in ((StatusBar)ctrl).Panels)
{
inCtrl.Text = "" ;
}
}
}
}
catch( Exception sysExcp )
{
}
finally
{
base.OnGotFocus(e);
}
}
#endregion
protected override void OnKeyDown(KeyEventArgs e)
{
try
{
int index;
string actual;
string found;
if ( ( e.Modifiers == Keys.Control ) || ( e.Modifiers == Keys.Alt ) ||
(e.KeyCode == Keys.Delete)
|| ( e.KeyCode == Keys.Back) || ( e.KeyCode == Keys.Left ) || (e.KeyCode ==
Keys.Right)
|| ( e.KeyCode == Keys.Tab ) || ( e.KeyCode == Keys.Up) || ( e.KeyCode ==
Keys.Down )
|| ( e.KeyCode == Keys.PageUp) || ( e.KeyCode == Keys.PageDown ) ||
(e.KeyCode == Keys.Home)
|| ( e.KeyCode == Keys.End))
{
return;
}
if ( e.KeyCode == Keys.OemMinus )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "-";
}
else
{
if ( e.KeyCode == Keys.D0 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "0";
}
else if ( e.KeyCode == Keys.D1 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "1";
}
else if ( e.KeyCode == Keys.D2 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "2";
}
else if ( e.KeyCode == Keys.D3 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "3";
}
else if ( e.KeyCode == Keys.D4 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "4";
}
else if ( e.KeyCode == Keys.D5 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "5";
}
else if ( e.KeyCode == Keys.D6 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "6";
}
else if ( e.KeyCode == Keys.D7 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "7";
}
else if ( e.KeyCode == Keys.D8 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "8";
}
else if ( e.KeyCode == Keys.D9 )
{
actual = this.Text.Substring( 0, this.SelectionStart ) + "9";
}
else
{
actual = this.Text.Substring( 0, this.SelectionStart ) +
e.KeyCode.ToString();
}
}
index = this.FindString(actual);
if (index > -1)
{
found = this.Items[index].ToString();
this.SelectedIndex = index;
this.SelectionStart = actual.Length;
this.SelectionLength = found.Length;
e.Handled = true;
}
else
{
e.Handled = true;
}
}
catch(Exception ex)
{
MessageBox.Show( ex.ToString() );
}
}
protected override void OnKeyUp(KeyEventArgs e)
{
if ( ( e.Modifiers == Keys.Control ) || ( e.Modifiers == Keys.Alt ) ||
(e.KeyCode == Keys.Delete)
|| ( e.KeyCode == Keys.Back) || ( e.KeyCode == Keys.Left ) || (e.KeyCode ==
Keys.Right)
|| ( e.KeyCode == Keys.Tab ) || ( e.KeyCode == Keys.Up) || ( e.KeyCode ==
Keys.Down )
|| ( e.KeyCode == Keys.PageUp) || ( e.KeyCode == Keys.PageDown ) ||
(e.KeyCode == Keys.Home)
|| ( e.KeyCode == Keys.End))
{
e.Handled = false;
}
else
{
e.Handled = true;
}
}
protected override void OnKeyPress(KeyPressEventArgs e)
{
if ( ( ( ( Keys )e.KeyChar == Keys.Delete) || ( ( Keys )e.KeyChar ==
Keys.Back) || ( ( Keys )e.KeyChar == Keys.Left )
|| (( Keys )e.KeyChar == Keys.Right) || ( ( Keys )e.KeyChar == Keys.Tab ) ||
( ( Keys )e.KeyChar == Keys.Up)
|| ( ( Keys )e.KeyChar == Keys.Down ) || ( ( Keys )e.KeyChar == Keys.PageUp)
|| ( ( Keys )e.KeyChar == Keys.PageDown )
|| (( Keys )e.KeyChar == Keys.Home) || ( ( Keys )e.KeyChar == Keys.End)))
{
e.Handled = false;
}
else
{
e.Handled = true;
}
}
#region OnLeave
/// <summary>
/// Sets/Resets the Selected value/Text in the combo when the focus leaves
the control
/// </summary>
/// <param name="e">EventArgs</param>
protected override void OnLeave(EventArgs e)
{
try
{
string thisText = this.Text.Trim();
if(this.FindString(thisText) != -1 && thisText != "")
{
this.SelectedIndex = this.FindString(this.Text);
}
else
{
this.SelectedIndex = -1;
this.Text = "";
}
}
catch(Exception ex)
{
}
finally
{
base.OnLeave (e);
}
}
#endregion
#region OnMouseMove
protected override void OnMouseMove(MouseEventArgs e)
{
try
{
this.toolTipCombo.Active = true;
ComboBox c = (ComboBox)this;
string s = c.Text.ToString();
Graphics g = c.CreateGraphics();
if(c.Width - 30 < g.MeasureString(s,c.Font).Width)
{
if (s!=this.toolTipCombo.GetToolTip(c).ToString())
{
this.toolTipCombo.SetToolTip(c,s);
}
}
else
{
this.toolTipCombo.SetToolTip(c,"");
}
}
catch(Exception ex)
{
}
finally
{
base.OnMouseMove(e);
}
}
#endregion
#region OnMouseLeave
protected override void OnMouseLeave(EventArgs e)
{
this.toolTipCombo.SetToolTip(this,"");
base.OnMouseLeave (e);
}
#endregion
}
#endregion
}
Regards,
Sanjeeva
