PasswordBoxExtender.cs

Toto je zdrojový kód souboru PasswordBoxExtender.cs

Adds Watermark support to Silverlight PasswordBox control.

using System;
using System.Windows;
using System.Windows.Controls;

namespace IMP.Windows.Controls
{
    /// <summary>
    /// Adds Watermark support to PasswordBox control
    /// </summary>
    /// <remarks>
    /// <c>Watermark</c> support
    /// </remarks>
    public class PasswordBoxExtender
    {
        #region property getters/setters
        /// <summary>
        /// Watermark attached dependency property
        /// </summary>
        public static readonly DependencyProperty WatermarkProperty = DependencyProperty.RegisterAttached("Watermark", typeof(object), typeof(PasswordBoxExtender), new PropertyMetadata(OnWatermarkPropertyChanged));

        /// <summary>
        /// Watermark Property getter
        /// </summary>
        public static object GetWatermark(DependencyObject source)
        {
            return (object)source.GetValue(PasswordBoxExtender.WatermarkProperty);
        }

        /// <summary>
        /// Watermark Property setter
        /// </summary>
        public static void SetWatermark(DependencyObject target, object value)
        {
            target.SetValue(PasswordBoxExtender.WatermarkProperty, value);
        }

        private static void OnWatermarkPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
        {
            var passwordBox = sender as PasswordBox;
            if (passwordBox != null)
            {
                passwordBox.Loaded -= PasswordBox_Loaded;
                passwordBox.PasswordChanged -= PasswordBox_PasswordChanged;
                passwordBox.Loaded += PasswordBox_Loaded;
                passwordBox.PasswordChanged += PasswordBox_PasswordChanged;

                OnWatermarkChanged(passwordBox);
                SetWatermarkState(passwordBox, true);
            }
        }

        private static void OnWatermarkChanged(PasswordBox passwordBox)
        {
            Control watermarkControl = passwordBox.GetValue(PasswordBoxExtender.WatermarkProperty) as Control;
            if (watermarkControl != null)
            {
                watermarkControl.IsTabStop = false;
                watermarkControl.IsHitTestVisible = false;
            }
        }
        #endregion

        #region private member functions
        private static void PasswordBox_Loaded(object sender, RoutedEventArgs e)
        {
            ((PasswordBox)sender).ApplyTemplate();
            SetWatermarkState((PasswordBox)sender, false);
        }

        private static void PasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            SetWatermarkState((PasswordBox)sender, true);
        }

        private static void SetWatermarkState(PasswordBox passwordBox, bool useTransitions)
        {
            object watermark = passwordBox.GetValue(PasswordBoxExtender.WatermarkProperty);

            // Update the WatermarkStates group
            if (watermark != null && string.IsNullOrEmpty(passwordBox.Password))
            {
                GoToState(passwordBox, useTransitions, "Watermarked", "Unwatermarked");
            }
            else
            {
                GoToState(passwordBox, useTransitions, "Unwatermarked");
            }
        }

        private static void GoToState(Control control, bool useTransitions, params string[] stateNames)
        {
            if (control == null)
            {
                throw new ArgumentNullException("control");
            }

            if (stateNames != null)
            {
                foreach (string str in stateNames)
                {
                    if (VisualStateManager.GoToState(control, str, useTransitions))
                    {
                        return;
                    }
                }
            }
        }
        #endregion
    }
}