XPlorerBar: A WPF Windows XP Style Explorer Bar Control

#region [       Copyright © 2008, Zona-Tools, all rights reserved.       ]
/*
 * 
    This source code is licensed under the Code Project Open License (CPOL).
    Check out http://www.codeproject.com/info/cpol10.aspx for further details.
 * 
*/
#endregion


#region [       Using namespaces       ]

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;

#endregion


namespace ZonaTools.XPlorerBar
{
    #region [       Theme definition structure       ]

    /// <summary>
    /// Represents a theme with its name and the path to its resource dictionary.
    /// </summary>
    public struct Theme
    {
        /// <summary>
        /// Name of the theme.
        /// </summary>
        public string Name;
        /// <summary>
        /// Path of the theme resource dictionary.
        /// </summary>
        public string DictionaryPath;

        /// <summary>
        /// Default constructor.
        /// </summary>
        /// <param name="name">Name of the theme.</param>
        /// <param name="dictionaryPath">Path of the theme resource dictionary.</param>
        public Theme(string name, string dictionaryPath)
        {
            Name = name;
            DictionaryPath = dictionaryPath;
        }
    }

    #endregion


    #region [       Theme names enumeration       ]

    /// <summary>
    /// Specifies the names of the most common themes.
    /// </summary>
    public enum Themes
    {
        /// <summary>
        /// Name used to unload the themes of an element.
        /// </summary>
        Default,
        /// <summary>
        /// Name of the Aero.NormalColor theme.
        /// </summary>
        Aero,
        /// <summary>
        /// Name of the Classic theme.
        /// </summary>
        Classic,
        /// <summary>
        /// Name of the Luna.NormalColor theme.
        /// </summary>
        LunaBlue,
        /// <summary>
        /// Name of the Luna.Homestead theme.
        /// </summary>
        LunaOliveGreen,
        /// <summary>
        /// Name of the Luna.Metallic theme.
        /// </summary>
        LunaSilver,
        /// <summary>
        /// Name of the Royale.NormalColor theme.
        /// </summary>
        Royale,
        /// <summary>
        /// Name of the Zune.NormalColor theme.
        /// </summary>
        Zune,
        /// <summary>
        /// Name of the Blend theme.
        /// </summary>
        Blend
    };
    
    #endregion


    /// <summary>
    /// Manages the themes used by any <c>FrameworkElement</c>.
    /// </summary>
    public static class ThemeManager
    {
        #region [       String definitions       ]

        private const string Lang_Caption =
            "Theme Management";
        private const string Lang_ChangeThemeToPb =
            "Unable to change the current theme because the '{0}' theme is not registered for the '{1}' objects.";
        private const string Lang_RegisterThemePb =
            "Unable to register the '{0}' theme for the '{1}' objects.";

        #endregion


        #region [       Fields       ]

        /// <summary>
        /// Represents the collection of all the registered themes.
        /// </summary>
        /// <remarks>
        /// The key of this dictionary represents the name used to register a theme.
        /// </remarks>
        private static Dictionary<string, ResourceDictionary>
            _registeredDictionaries = new Dictionary<string, ResourceDictionary>();

        #endregion


        #region [       Dependency properties       ]

        #region Theme attached property

        //===========================================================================
        /// <summary>
        /// Identifies the <c>Theme</c> attached property.
        /// </summary>
        /// <remarks>The default value is <c>Default</c>.</remarks>
        //===========================================================================
        public static readonly DependencyProperty ThemeProperty =
            DependencyProperty.RegisterAttached("Theme", 
            typeof(string), typeof(ThemeManager),
                new FrameworkPropertyMetadata(Themes.Default.ToString(),
                    FrameworkPropertyMetadataOptions.None,
                    new PropertyChangedCallback(OnThemeChanged)));

        /// <summary>
        /// Gets the value of the <c>Theme</c> attached property for a 
        /// specified <c>FrameworkElement</c>.
        /// </summary>
        [Category(XPlorerBar.CATEGORYNAME), AttachedPropertyBrowsableForType(typeof(FrameworkElement))]
        public static string GetTheme(DependencyObject d)
        {
            if (d == null)
                throw new ArgumentNullException("d");
            return (string)d.GetValue(ThemeProperty);
        }

        /// <summary>
        /// Sets the value of the <c>Theme</c> attached property to a 
        /// specified <c>FrameworkElement</c>.
        /// </summary>
        public static void SetTheme(DependencyObject d, string value)
        {
            if (d == null)
                throw new ArgumentNullException("d");
            d.SetValue(ThemeProperty, value);
        }

        /// <summary>
        /// Invoked whenever the <c>Theme</c> attached property value has 
        /// been updated.
        /// </summary>
        /// <param name="d">The <c>DependencyObject</c> on which the property has 
        /// changed value.</param>
        /// <param name="e">Event data that is issued by any event that tracks changes 
        /// to the effective value of this property.</param>
        private static void OnThemeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            //Gets the element on which apply the new theme
            FrameworkElement element = d as FrameworkElement;

            //Makes sure the arguments are valid
            if (element == null)
                throw new ArgumentNullException("d");
            if (e == null)
                throw new ArgumentNullException("e");

            //-------------------------------------------------------------
            //Removes the current theme dictionary from element's resources
            //-------------------------------------------------------------

            //Gets the name of the current theme
            string curThemeName = e.OldValue as string;

            //If the current theme is the default theme, there's nothing to remove
            if (!curThemeName.Equals(Themes.Default.ToString()))
            {
                //Gets the registered name of the current theme
                string curRegisteredThemeName = 
                    GetRegistrationName(curThemeName, element.GetType());

                //If the current theme is registered
                if (_registeredDictionaries.ContainsKey(curRegisteredThemeName))
                {
                    //Gets the resource dictionary of the current theme
                    ResourceDictionary curThemeDictionary =
                        _registeredDictionaries[curRegisteredThemeName];
                    //and removes it
                    element.Resources.MergedDictionaries.Remove(curThemeDictionary);
                }
            }

            //----------------------------------------------------
            //Adds the new theme dictionary to element's resources
            //----------------------------------------------------

            //Gets the name of the new theme
            string newThemeName = e.NewValue as string;

            //If the new theme is the default theme, there's nothing to add
            if (!newThemeName.Equals(Themes.Default.ToString()))
            {
                //Gets the registered name of the new theme
                string newRegisteredThemeName =
                    GetRegistrationName(newThemeName, element.GetType());

                //If the new theme is not registered
                if (!_registeredDictionaries.ContainsKey(newRegisteredThemeName))
                {
                    //Displays an error message
                    MessageBox.Show(
                        string.Format(Lang_ChangeThemeToPb, newThemeName, element.GetType().ToString()),
                        Lang_Caption, MessageBoxButton.OK, MessageBoxImage.Warning);
                }
                else
                {
                    //Gets the resource dictionary of the new theme
                    ResourceDictionary newThemeDictionary =
                        _registeredDictionaries[newRegisteredThemeName];
                    //and applies it to the source element
                    element.Resources.MergedDictionaries.Add(newThemeDictionary);
                }
            }
        }

        #endregion

        #endregion


        #region [       Registers a new theme       ]

        //===========================================================================
        /// <summary>
        /// Registers a new theme with a specified name and a specified <c>Uri</c>.
        /// </summary>
        /// <param name="theme">Theme to register.</param>
        /// <param name="ownerType">The owner type that is registering the theme.
        /// </param>
        //===========================================================================
        public static void RegisterTheme(Theme theme, Type ownerType)
        {
            //Makes sure the arguments are valid
            if ((theme.Name == null) || (theme.DictionaryPath == null))
                throw new ArgumentNullException("theme");
            if (ownerType == null)
                throw new ArgumentNullException("ownerType");

            //Gets the registration name
            string registrationName = 
                GetRegistrationName(theme.Name, ownerType);

            //Checks that the new theme is not the default theme and 
            //that it is not already registered
            if (theme.Name.Equals(Themes.Default.ToString()) ||
                _registeredDictionaries.ContainsKey(registrationName))
                return;

            try
            {
                //Creates the Uri of the specified theme
                Uri themeUri = new Uri(theme.DictionaryPath, UriKind.Relative);

                //Registers the new theme
                _registeredDictionaries[registrationName] =
                    Application.LoadComponent(themeUri) as ResourceDictionary;
            }
            catch
            {
                //Dislays an error message
                MessageBox.Show(
                    string.Format(Lang_RegisterThemePb, theme.Name, ownerType.ToString()),
                    Lang_Caption, MessageBoxButton.OK, MessageBoxImage.Warning);
            }
        }


        //===========================================================================
        /// <summary>
        /// Gets the name used for the registration of the specified theme.
        /// </summary>
        /// <param name="themeName">Name of the theme to register.</param>
        /// <param name="ownerType">The owner type that is registering the theme.
        /// </param>
        /// <returns>Name used for the registration of the specified theme.</returns>
        //===========================================================================
        private static string GetRegistrationName(string themeName, Type ownerType)
        {
            //Sets the registration name (Type name;theme name)
            string registrationName =
                string.Format("{0};{1}", ownerType.ToString(), themeName);

            return registrationName;
        }

        #endregion
    }
}