In this example I will demonstrate how how to display a border around the TextBox when it has focused and show how to add a property for disabling and enabling the caret.
To draw the border I make sure that there is 1 pixel of space around the actual TextBox control. In the OnResize event of the composite control I set the bounds of the inner TextBox the bounds of the composite control minus 1 pixel on each side. If the inner TextBox is not in Multiline mode then the height of the control is forced to match its font size, if so then I resize the composite control to be 1 pixel taller. And draw the border I just clear the drawing surface with the highlight system color if it is Focused, and with white if not.
To enable and disable the caret, we add a boolean property called EnableCaret. This property is checked every time the control receives or loses focus, to call the native HideCaret() and ShowCaret(). As I demonstrated in my previous article called How to hide the TextBox caret in .NETCF
Here's how it looks like:
And here's the code:
using System;using System.Drawing;using System.Runtime.InteropServices;using System.Windows.Forms;namespace ExtendedTextBox{public class TextBoxEx : Control
{[DllImport("coredll.dll")]
static extern bool HideCaret(IntPtr hwnd);
[DllImport("coredll.dll")]
static extern bool ShowCaret(IntPtr hwnd);
private TextBox textBox;
public TextBoxEx() {textBox = new TextBox();
textBox.GotFocus += (sender, e) => OnGotFocus(EventArgs.Empty); textBox.LostFocus += (sender, e) => OnLostFocus(EventArgs.Empty); textBox.TextChanged += (sender, e) => OnTextChanged(EventArgs.Empty);textBox.KeyDown += (sender, e) => OnKeyDown(e);
textBox.KeyPress += (sender, e) => OnKeyPress(e);
textBox.KeyUp += (sender, e) => OnKeyUp(e);
Controls.Add(textBox);
}
public bool EnabledCaret { get; set; }
#region Wrapped Propertiespublic override Font Font
{get { return base.Font; }
set {if (Environment.OSVersion.Platform != PlatformID.WinCE)
{var font = new Font(value.Name, value.Size, value.Style);
base.Font = textBox.Font = font;}
elsebase.Font = textBox.Font = value;
}
}
public override string Text
{get { return textBox.Text; }
set { textBox.Text = value; }
}
public bool AcceptsReturn
{get { return textBox.AcceptsReturn; }
set { textBox.AcceptsReturn = value; }
}
public bool AcceptsTab
{get { return textBox.AcceptsTab; }
set { textBox.AcceptsTab = value; }
}
public bool CanUndo
{get { return textBox.CanUndo; }
}
public bool Focused
{get { return textBox.Focused; }
}
public new IntPtr Handle
{get { return textBox.Handle; }
}
public bool HideSelection
{get { return textBox.HideSelection; }
set { textBox.HideSelection = value; }
}
public int MaxLength
{get { return textBox.MaxLength; }
set { textBox.MaxLength = value; }
}
public bool Modified
{get { return textBox.Modified; }
set { textBox.Modified = value; }
}
public bool Multiline
{get { return textBox.Multiline; }
set { textBox.Multiline = value; }
}
public char PasswordChar
{get { return textBox.PasswordChar; }
set { textBox.PasswordChar = value; }
}
public bool ReadOnly
{get { return textBox.ReadOnly; }
set { textBox.ReadOnly = value; }
}
public override Color BackColor
{get { return textBox.BackColor; }
set { textBox.BackColor = value; }
}
public ScrollBars ScrollBars
{get { return textBox.ScrollBars; }
set { textBox.ScrollBars = value; }
}
public string SelectedText
{get { return textBox.SelectedText; }
set { textBox.SelectedText = value; }
}
public int SelectionLength
{get { return textBox.SelectionLength; }
set { textBox.SelectionLength = value; }
}
public int SelectionStart
{get { return textBox.SelectionStart; }
set { textBox.SelectionStart = value; }
}
public HorizontalAlignment TextAlign
{get { return textBox.TextAlign; }
set { textBox.TextAlign = value; }
}
public int TextLength
{get { return textBox.TextLength; }
}
public bool WordWrap
{get { return textBox.WordWrap; }
set { textBox.WordWrap = value; }
}
#endregion #region Wrapped Methodspublic void ScrollToCaret()
{textBox.ScrollToCaret();
}
public void Select(int start, int length)
{textBox.Select(start, length);
}
public void SelectAll()
{textBox.SelectAll();
}
public void Undo()
{textBox.Undo();
}
#endregion #region Overridden Methodsprotected override void OnResize(EventArgs e)
{ base.OnResize(e);textBox.Bounds = new Rectangle(
1,
1,
ClientSize.Width - 2,
ClientSize.Height - 2);
Height = textBox.Height + 2;
}
protected override void OnGotFocus(EventArgs e)
{ base.OnGotFocus(e);Invalidate();
if (!EnabledCaret)HideCaret(Handle);
}
protected override void OnLostFocus(EventArgs e)
{ base.OnLostFocus(e);Invalidate();
if (!EnabledCaret)ShowCaret(Handle);
}
protected override void OnPaint(PaintEventArgs e)
{e.Graphics.Clear(textBox.Focused ? SystemColors.Highlight : Color.White);
}
protected override void OnPaintBackground(PaintEventArgs e)
{}
protected override void Dispose(bool disposing)
{ base.Dispose(disposing);textBox.Dispose();
}
#endregion}
}
Hope you find this useful. If you need the Visual Studio solution then you can grab it here.
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