Watermarked TextBox

Well, I love mucking around in code and I recently decided to see how easy it would be to knock together a user control that would work in both WPF and Silverlight. If you keep it simple, it is really really easy to do. To this end, I present to you the WatermarkTextbox.

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.ComponentModel;

namespace WaterBox
{
  public class WatermarkTextBox : TextBox, INotifyPropertyChanged
  {
    public WatermarkTextBox()
    {
      ApplyWatermark();
    }

 

    protected virtual void Changed(string propertyName)
    {
      ApplyWatermark();
      PropertyChangedEventHandler handler = PropertyChanged;
      if (handler != null)
      {
        handler(this, new PropertyChangedEventArgs(propertyName));
      }
    }

    private string _watermarkText = “Watermark”;
    public string WatermarkText
    {
      get
      {
        return _watermarkText;
      }
      set
      {
        if (_watermarkText != value)
        {
          if (string.IsNullOrEmpty(Text) || Text == _watermarkText)
          {
            Text = value;
          }
          _watermarkText = value;
          Changed(“WatermarkText”

);
        }
      }
    } 

 

 

 

    private System.Windows.Media.Brush _watermarkForeground = new SolidColorBrush(Colors.LightGray);
    public System.Windows.Media.Brush WatermarkForeground
    {
      get
      {
        return _watermarkForeground;
      }
      set
      {
        if (_watermarkForeground != value)
        {
          _watermarkForeground = value;
          Changed(“WatermarkForeground”

);
        }
      }
    } 

 

 

 

    private System.Windows.Media.Brush _watermarkBackground = new SolidColorBrush(Colors.Yellow);
    public System.Windows.Media.Brush WatermarkBackground
    {
      get
      {
        return _watermarkBackground;
      }
      set
      {
        if (_watermarkBackground != value)
        {
          _watermarkBackground = value;
         Changed(“WatermarkBackground”

);
        }
      }
    } 

 

 

 

    private System.Windows.Media.Brush _standardForeground = new SolidColorBrush(Colors.Black);
    public System.Windows.Media.Brush StandardForeground
    {
      get
      {
        return _standardForeground;
      }
      set
      {
        if (_standardForeground != value)
        {
          _standardForeground = value;
          Changed(“StandardForeground”

);
        }
      }
    } 

 

 

 

    private System.Windows.Media.Brush _standardBackground = new SolidColorBrush(Colors.White);
    public System.Windows.Media.Brush StandardBackground
    {
      get
      {
        return _standardBackground;
      }
      set
      {
        if (_standardBackground != value)
        {
          _standardBackground = value;
          Changed(“StandardBackground”);
        }
      }
   

} 

 

 

 

    private void 

SetStandard()
    {
      Foreground = StandardForeground;
      Background = StandardBackground;
    } 

 

 

 

    protected override void OnGotFocus(RoutedEventArgs  e)
    {
      if (Text == WatermarkText)
      {
        Text = string.Empty;
        SetStandard();
      }
      base

.OnGotFocus(e);
    } 

 

 

 

    protected override void OnLostFocus(RoutedEventArgs e)
    {
      Text = Text.Trim();
      if (Text.Length == 0)
      {
        ApplyWatermark();
      }
      base

.OnLostFocus(e);
    } 

 

 

 

    private void ApplyWatermark()
    {
      if (string.IsNullOrEmpty(Text) || Text == WatermarkText)
      {
        Text = WatermarkText;
        Foreground = WatermarkForeground;
        Background = WatermarkBackground;
      }
    }

    #region

 

INotifyPropertyChanged Members
    public event PropertyChangedEventHandler PropertyChanged;
    #endregion
  }
}

 

Please feel free to use this class as you like. It comes with no warranty because it’s intended as a proof of concept only. It can do with a tidy up, and it should use Coerce values but I leave that for you to do.