wpftoolkit/ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/ChildWindow/Implementation/ChildWindow.cs

/************************************************************************

   Extended WPF Toolkit

   Copyright (C) 2010-2012 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://wpftoolkit.codeplex.com/license 

   This program can be provided to you by Xceed Software Inc. under a
   proprietary commercial license agreement for use in non-Open Source
   projects. The commercial version of Extended WPF Toolkit also includes
   priority technical support, commercial updates, and many additional 
   useful WPF controls if you license Xceed Business Suite for WPF.

   Visit http://xceed.com and follow @datagrid on Twitter.

  **********************************************************************/

using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Threading;

namespace Xceed.Wpf.Toolkit
{
  [TemplatePart( Name = PART_DragWidget, Type = typeof( Border ) )]
  [TemplatePart( Name = PART_CloseButton, Type = typeof( Button ) )]
  [TemplatePart( Name = PART_WindowRoot, Type = typeof( Grid ) )]
  [TemplatePart( Name = PART_Root, Type = typeof( Grid ) )]
  public class ChildWindow : ContentControl
  {
    private const string PART_DragWidget = "PART_DragWidget";
    private const string PART_CloseButton = "PART_CloseButton";
    private const string PART_WindowRoot = "PART_WindowRoot";
    private const string PART_Root = "PART_Root";

    #region Private Members

    private Grid _root;
    private TranslateTransform _moveTransform = new TranslateTransform();
    private bool _startupPositionInitialized;
    private bool _isMouseCaptured;
    private Point _clickPoint;
    private Point _oldPosition;
    private Border _dragWidget;
    private FrameworkElement _parentContainer;
    private Rectangle _modalLayer = new Rectangle();
    private Canvas _modalLayerPanel = new Canvas();

    private const int _horizaontalOffset = 3;
    private const int _verticalOffset = 3;

    bool _ignorePropertyChanged;

    #endregion //Private Members

    #region Properties

    #region Internal Properties

    internal Grid WindowRoot
    {
      get;
      private set;
    }
    internal Thumb DragWidget
    {
      get;
      private set;
    }
    internal Button MinimizeButton
    {
      get;
      private set;
    }
    internal Button MaximizeButton
    {
      get;
      private set;
    }
    internal Button CloseButton
    {
      get;
      private set;
    }

    #endregion //Internal Properties

    #region Public Properties

    #region Caption

    public static readonly DependencyProperty CaptionProperty = DependencyProperty.Register( "Caption", typeof( object ), typeof( ChildWindow ), new UIPropertyMetadata( String.Empty ) );
    public object Caption
    {
      get
      {
        return ( object )GetValue( CaptionProperty );
      }
      set
      {
        SetValue( CaptionProperty, value );
      }
    }

    #endregion //Caption

    #region CaptionForeground

    public static readonly DependencyProperty CaptionForegroundProperty = DependencyProperty.Register( "CaptionForeground", typeof( Brush ), typeof( ChildWindow ), new UIPropertyMetadata( null ) );
    public Brush CaptionForeground
    {
      get
      {
        return ( Brush )GetValue( CaptionForegroundProperty );
      }
      set
      {
        SetValue( CaptionForegroundProperty, value );
      }
    }

    #endregion //CaptionForeground

    #region CloseButtonStyle

    public static readonly DependencyProperty CloseButtonStyleProperty = DependencyProperty.Register( "CloseButtonStyle", typeof( Style ), typeof( ChildWindow ), new PropertyMetadata( null ) );
    public Style CloseButtonStyle
    {
      get
      {
        return ( Style )GetValue( CloseButtonStyleProperty );
      }
      set
      {
        SetValue( CloseButtonStyleProperty, value );
      }
    }

    #endregion //CloseButtonStyle

    #region CloseButtonVisibility

    public static readonly DependencyProperty CloseButtonVisibilityProperty = DependencyProperty.Register( "CloseButtonVisibility", typeof( Visibility ), typeof( ChildWindow ), new PropertyMetadata( Visibility.Visible ) );
    public Visibility CloseButtonVisibility
    {
      get
      {
        return ( Visibility )GetValue( CloseButtonVisibilityProperty );
      }
      set
      {
        SetValue( CloseButtonVisibilityProperty, value );
      }
    }

    #endregion //CloseButtonVisibility

    #region DialogResult

    private bool? _dialogResult;
    /// <summary>
    /// Gets or sets a value indicating whether the ChildWindow was accepted or canceled.
    /// </summary>
    /// <value>
    /// True if the child window was accepted; false if the child window was
    /// canceled. The default is null.
    /// </value>
    [TypeConverter( typeof( NullableBoolConverter ) )]
    public bool? DialogResult
    {
      get
      {
        return _dialogResult;
      }
      set
      {
        if( _dialogResult != value )
        {
          _dialogResult = value;
          Close();
        }
      }
    }

    #endregion //DialogResult

    #region DesignerWindowState

    public static readonly DependencyProperty DesignerWindowStateProperty = DependencyProperty.Register( "DesignerWindowState", typeof( WindowState ), typeof( ChildWindow ), new PropertyMetadata( WindowState.Closed, OnDesignerWindowStatePropertyChanged ) );
    public WindowState DesignerWindowState
    {
      get
      {
        return ( WindowState )GetValue( DesignerWindowStateProperty );
      }
      set
      {
        SetValue( DesignerWindowStateProperty, value );
      }
    }

    private static void OnDesignerWindowStatePropertyChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = d as ChildWindow;
      if( childWindow != null )
        childWindow.OnDesignerWindowStatePropertyChanged( ( WindowState )e.OldValue, ( WindowState )e.NewValue );
    }

    protected virtual void OnDesignerWindowStatePropertyChanged( WindowState oldValue, WindowState newValue )
    {
      if( DesignerProperties.GetIsInDesignMode( this ) )
      {
        Visibility = newValue == Xceed.Wpf.Toolkit.WindowState.Open ? Visibility.Visible : Visibility.Collapsed;
      }
    }

    #endregion //DesignerWindowState

    #region FocusedElement

    public static readonly DependencyProperty FocusedElementProperty = DependencyProperty.Register( "FocusedElement", typeof( FrameworkElement ), typeof( ChildWindow ), new UIPropertyMetadata( null ) );
    public FrameworkElement FocusedElement
    {
      get
      {
        return ( FrameworkElement )GetValue( FocusedElementProperty );
      }
      set
      {
        SetValue( FocusedElementProperty, value );
      }
    }

    #endregion

    #region IsModal

    public static readonly DependencyProperty IsModalProperty = DependencyProperty.Register( "IsModal", typeof( bool ), typeof( ChildWindow ), new UIPropertyMetadata( false, new PropertyChangedCallback( OnIsModalPropertyChanged ) ) );
    public bool IsModal
    {
      get
      {
        return ( bool )GetValue( IsModalProperty );
      }
      set
      {
        SetValue( IsModalProperty, value );
      }
    }

    private static void OnIsModalPropertyChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = d as ChildWindow;
      if( childWindow != null )
        childWindow.OnIsModalChanged( ( bool )e.OldValue, ( bool )e.NewValue );
    }

    private void OnIsModalChanged( bool oldValue, bool newValue )
    {
      if( newValue )
      {
        KeyboardNavigation.SetTabNavigation( this, KeyboardNavigationMode.Cycle );
        ShowModalLayer();
      }
      else
      {
        KeyboardNavigation.SetTabNavigation( this, KeyboardNavigationMode.Continue );
        HideModalLayer();
      }
    }

    #endregion //IsModal

    #region Left

    public static readonly DependencyProperty LeftProperty = DependencyProperty.Register( "Left", typeof( double ), typeof( ChildWindow ), new PropertyMetadata( 0.0, new PropertyChangedCallback( OnLeftPropertyChanged ) ) );
    public double Left
    {
      get
      {
        return ( double )GetValue( LeftProperty );
      }
      set
      {
        SetValue( LeftProperty, value );
      }
    }

    private static void OnLeftPropertyChanged( DependencyObject obj, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = obj as ChildWindow;
      if( childWindow != null )
        childWindow.OnLeftPropertyChanged( ( double )e.OldValue, ( double )e.NewValue );
    }

    private void OnLeftPropertyChanged( double oldValue, double newValue )
    {
      Left = GetRestrictedLeft();
      ProcessMove( newValue - oldValue, 0 );
    }

    #endregion //Left

    #region OverlayBrush

    public static readonly DependencyProperty OverlayBrushProperty = DependencyProperty.Register( "OverlayBrush", typeof( Brush ), typeof( ChildWindow ), new PropertyMetadata( Brushes.Gray, OnOverlayBrushChanged ) );
    public Brush OverlayBrush
    {
      get
      {
        return ( Brush )GetValue( OverlayBrushProperty );
      }
      set
      {
        SetValue( OverlayBrushProperty, value );
      }
    }

    private static void OnOverlayBrushChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = d as ChildWindow;
      if( childWindow != null )
        childWindow.OnOverlayBrushChanged( ( Brush )e.OldValue, ( Brush )e.NewValue );
    }

    protected virtual void OnOverlayBrushChanged( Brush oldValue, Brush newValue )
    {
      _modalLayer.Fill = newValue;
    }

    #endregion //OverlayBrush

    #region OverlayOpacity

    public static readonly DependencyProperty OverlayOpacityProperty = DependencyProperty.Register( "OverlayOpacity", typeof( double ), typeof( ChildWindow ), new PropertyMetadata( 0.5, OnOverlayOpacityChanged ) );
    public double OverlayOpacity
    {
      get
      {
        return ( double )GetValue( OverlayOpacityProperty );
      }
      set
      {
        SetValue( OverlayOpacityProperty, value );
      }
    }

    private static void OnOverlayOpacityChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = d as ChildWindow;
      if( childWindow != null )
        childWindow.OnOverlayOpacityChanged( ( double )e.OldValue, ( double )e.NewValue );
    }

    protected virtual void OnOverlayOpacityChanged( double oldValue, double newValue )
    {
      _modalLayer.Opacity = newValue;
    }

    #endregion //OverlayOpacity

    #region Top

    public static readonly DependencyProperty TopProperty = DependencyProperty.Register( "Top", typeof( double ), typeof( ChildWindow ), new PropertyMetadata( 0.0, new PropertyChangedCallback( OnTopPropertyChanged ) ) );
    public double Top
    {
      get
      {
        return ( double )GetValue( TopProperty );
      }
      set
      {
        SetValue( TopProperty, value );
      }
    }

    private static void OnTopPropertyChanged( DependencyObject obj, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = obj as ChildWindow;
      if( childWindow != null )
        childWindow.OnTopPropertyChanged( ( double )e.OldValue, ( double )e.NewValue );
    }

    private void OnTopPropertyChanged( double oldValue, double newValue )
    {
      Top = GetRestrictedTop();
      ProcessMove( 0, newValue - oldValue );
    }

    #endregion //TopProperty

    #region WindowBackground

    public static readonly DependencyProperty WindowBackgroundProperty = DependencyProperty.Register( "WindowBackground", typeof( Brush ), typeof( ChildWindow ), new PropertyMetadata( null ) );
    public Brush WindowBackground
    {
      get
      {
        return ( Brush )GetValue( WindowBackgroundProperty );
      }
      set
      {
        SetValue( WindowBackgroundProperty, value );
      }
    }

    #endregion //WindowBackground

    #region WindowBorderBrush

    public static readonly DependencyProperty WindowBorderBrushProperty = DependencyProperty.Register( "WindowBorderBrush", typeof( Brush ), typeof( ChildWindow ), new PropertyMetadata( null ) );
    public Brush WindowBorderBrush
    {
      get
      {
        return ( Brush )GetValue( WindowBorderBrushProperty );
      }
      set
      {
        SetValue( WindowBorderBrushProperty, value );
      }
    }

    #endregion //WindowBorderBrush

    #region WindowOpacity

    public static readonly DependencyProperty WindowOpacityProperty = DependencyProperty.Register( "WindowOpacity", typeof( double ), typeof( ChildWindow ), new PropertyMetadata( null ) );
    public double WindowOpacity
    {
      get
      {
        return ( double )GetValue( WindowOpacityProperty );
      }
      set
      {
        SetValue( WindowOpacityProperty, value );
      }
    }

    #endregion //WindowOpacity

    #region WindowStartupLocation

    public static readonly DependencyProperty WindowStartupLocationProperty = DependencyProperty.Register( "WindowStartupLocation", typeof( WindowStartupLocation ), typeof( ChildWindow ), new UIPropertyMetadata( WindowStartupLocation.Manual, OnWindowStartupLocationChanged ) );
    public WindowStartupLocation WindowStartupLocation
    {
      get
      {
        return ( WindowStartupLocation )GetValue( WindowStartupLocationProperty );
      }
      set
      {
        SetValue( WindowStartupLocationProperty, value );
      }
    }

    private static void OnWindowStartupLocationChanged( DependencyObject o, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = o as ChildWindow;
      if( childWindow != null )
        childWindow.OnWindowStartupLocationChanged( ( WindowStartupLocation )e.OldValue, ( WindowStartupLocation )e.NewValue );
    }

    protected virtual void OnWindowStartupLocationChanged( WindowStartupLocation oldValue, WindowStartupLocation newValue )
    {
      // TODO: Add your property changed side-effects. Descendants can override as well.
    }

    #endregion //WindowStartupLocation

    #region WindowState

    public static readonly DependencyProperty WindowStateProperty = DependencyProperty.Register( "WindowState", typeof( WindowState ), typeof( ChildWindow ), new FrameworkPropertyMetadata( WindowState.Closed, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnWindowStatePropertyChanged ) );
    public WindowState WindowState
    {
      get
      {
        return ( WindowState )GetValue( WindowStateProperty );
      }
      set
      {
        SetValue( WindowStateProperty, value );
      }
    }

    private static void OnWindowStatePropertyChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )
    {
      ChildWindow childWindow = d as ChildWindow;
      if( childWindow != null )
        childWindow.OnWindowStatePropertyChanged( ( WindowState )e.OldValue, ( WindowState )e.NewValue );
    }

    protected virtual void OnWindowStatePropertyChanged( WindowState oldValue, WindowState newValue )
    {
      if( !DesignerProperties.GetIsInDesignMode( this ) )
      {
        if( !_ignorePropertyChanged )
          SetWindowState( newValue );
      }
      else
      {
        Visibility = DesignerWindowState == Xceed.Wpf.Toolkit.WindowState.Open ? Visibility.Visible : System.Windows.Visibility.Collapsed;
      }
    }

    #endregion //WindowState

    #endregion //Public Properties

    #endregion //Properties

    #region Constructors

    static ChildWindow()
    {
      DefaultStyleKeyProperty.OverrideMetadata( typeof( ChildWindow ), new FrameworkPropertyMetadata( typeof( ChildWindow ) ) );
    }

    public ChildWindow()
    {
      DesignerWindowState = Xceed.Wpf.Toolkit.WindowState.Open;

      IsVisibleChanged += ChildWindow_IsVisibleChanged;

      _modalLayer.Fill = OverlayBrush;
      _modalLayer.Opacity = OverlayOpacity;
    }

    #endregion //Constructors

    #region Base Class Overrides

    public override void OnApplyTemplate()
    {
      base.OnApplyTemplate();

      if( _dragWidget != null )
      {
        _dragWidget.RemoveHandler( UIElement.MouseLeftButtonDownEvent, new MouseButtonEventHandler( HeaderLeftMouseButtonDown ) );
        _dragWidget.RemoveHandler( UIElement.MouseLeftButtonUpEvent, new MouseButtonEventHandler( HeaderMouseLeftButtonUp ) );
        _dragWidget.MouseMove -= ( o, e ) => HeaderMouseMove( e );
      }

      _dragWidget = GetTemplateChild( PART_DragWidget ) as Border;

      if( _dragWidget != null )
      {
        _dragWidget.AddHandler( UIElement.MouseLeftButtonDownEvent, new MouseButtonEventHandler( HeaderLeftMouseButtonDown ), true );
        _dragWidget.AddHandler( UIElement.MouseLeftButtonUpEvent, new MouseButtonEventHandler( HeaderMouseLeftButtonUp ), true );
        _dragWidget.MouseMove += ( o, e ) => HeaderMouseMove( e );
      }

      if( CloseButton != null )
        CloseButton.Click -= ( o, e ) => Close();

      CloseButton = GetTemplateChild( PART_CloseButton ) as Button;

      if( CloseButton != null )
        CloseButton.Click += ( o, e ) => Close();

      WindowRoot = GetTemplateChild( PART_WindowRoot ) as Grid;
      WindowRoot.RenderTransform = _moveTransform;

      _parentContainer = VisualTreeHelper.GetParent( this ) as FrameworkElement;
      _parentContainer.LayoutUpdated += ParentContainer_LayoutUpdated;
      _parentContainer.SizeChanged += ParentContainer_SizeChanged;

      //initialize our modal background width/height
      _modalLayer.Height = _parentContainer.ActualHeight;
      _modalLayer.Width = _parentContainer.ActualWidth;

      //this is for XBAP applications only. When inside an XBAP the parent container has no height or width until it has loaded. Therefore
      //we need to handle the loaded event and reposition the window.
      if( System.Windows.Interop.BrowserInteropHelper.IsBrowserHosted )
      {
        _parentContainer.Loaded += ( o, e ) =>
            {
              ExecuteOpen();
            };
      }

      _root = GetTemplateChild( PART_Root ) as Grid;

#if VS2008
      FocusVisualStyle = null;
#else
      Style focusStyle = _root.Resources[ "FocusVisualStyle" ] as Style;
      if( focusStyle != null )
      {
        Setter focusStyleDataContext = new Setter( Control.DataContextProperty, this );
        focusStyle.Setters.Add( focusStyleDataContext );
        FocusVisualStyle = focusStyle;
      }
#endif
      _root.Children.Add( _modalLayerPanel );
    }

    protected override void OnGotFocus( RoutedEventArgs e )
    {
      Action action = () =>
      {
        if( FocusedElement != null )
          FocusedElement.Focus();
      };

      Dispatcher.BeginInvoke( DispatcherPriority.ApplicationIdle, action );
    }

    protected override void OnKeyDown( KeyEventArgs e )
    {
      base.OnKeyDown( e );

      if( WindowState == WindowState.Open )
      {
        switch( e.Key )
        {
          case Key.Left:
            this.Left -= _horizaontalOffset;
            e.Handled = true;
            break;

          case Key.Right:
            this.Left += _horizaontalOffset;
            e.Handled = true;
            break;

          case Key.Down:
            this.Top += _verticalOffset;
            e.Handled = true;
            break;

          case Key.Up:
            this.Top -= _verticalOffset;
            e.Handled = true;
            break;
        }
      }
    }

    #endregion //Base Class Overrides

    #region Event Handlers

    void ChildWindow_IsVisibleChanged( object sender, DependencyPropertyChangedEventArgs e )
    {
      if( ( bool )e.NewValue )
        Focus();
    }

    void HeaderLeftMouseButtonDown( object sender, MouseButtonEventArgs e )
    {
      e.Handled = true;
      Focus();
      _dragWidget.CaptureMouse();
      _isMouseCaptured = true;
      _clickPoint = e.GetPosition( null ); //save off the mouse position
      _oldPosition = new Point( Left, Top ); //save off our original window position
    }

    private void HeaderMouseLeftButtonUp( object sender, MouseButtonEventArgs e )
    {
      e.Handled = true;
      _dragWidget.ReleaseMouseCapture();
      _isMouseCaptured = false;
    }

    private void HeaderMouseMove( MouseEventArgs e )
    {
      if( _isMouseCaptured && Visibility == Visibility.Visible )
      {
        Point currentPosition = e.GetPosition( null ); //our current mouse position

        Left = _oldPosition.X + ( currentPosition.X - _clickPoint.X );
        Top = _oldPosition.Y + ( currentPosition.Y - _clickPoint.Y );

        //this helps keep our mouse position in sync with the drag widget position
        Point dragWidgetPosition = e.GetPosition( _dragWidget );
        if( dragWidgetPosition.X < 0 || dragWidgetPosition.X > _dragWidget.ActualWidth || dragWidgetPosition.Y < 0 || dragWidgetPosition.Y > _dragWidget.ActualHeight )
        {
          return;
        }

        _oldPosition = new Point( Left, Top );
        _clickPoint = e.GetPosition( Window.GetWindow( this ) ); //store the point where we are relative to the window
      }
    }

    private void ParentContainer_LayoutUpdated( object sender, EventArgs e )
    {
      if( DesignerProperties.GetIsInDesignMode( this ) )
        return;

      //we only want to set the start position if this is the first time the control has bee initialized
      if( !_startupPositionInitialized )
      {
        ExecuteOpen();
        _startupPositionInitialized = true;
      }
    }

    void ParentContainer_SizeChanged( object sender, SizeChangedEventArgs e )
    {
      //resize our modal layer
      _modalLayer.Height = e.NewSize.Height;
      _modalLayer.Width = e.NewSize.Width;

      //reposition our window
      Left = GetRestrictedLeft();
      Top = GetRestrictedTop();
    }

    #endregion //Event Handlers

    #region Methods

    #region Private

    private double GetRestrictedLeft()
    {
      if( Left < 0 )
        return 0;

      if( _parentContainer != null )
      {
        if( Left + WindowRoot.ActualWidth > _parentContainer.ActualWidth && _parentContainer.ActualWidth != 0 )
        {
          double left = _parentContainer.ActualWidth - WindowRoot.ActualWidth;
          return left < 0 ? 0 : left;
        }
      }

      return Left;
    }

    private double GetRestrictedTop()
    {
      if( Top < 0 )
        return 0;

      if( _parentContainer != null )
      {
        if( Top + WindowRoot.ActualHeight > _parentContainer.ActualHeight && _parentContainer.ActualHeight != 0 )
        {
          double top = _parentContainer.ActualHeight - WindowRoot.ActualHeight;
          return top < 0 ? 0 : top;
        }
      }

      return Top;
    }

    private void SetWindowState( WindowState state )
    {
      switch( state )
      {
        case WindowState.Closed:
          {
            ExecuteClose();
            break;
          }
        case WindowState.Open:
          {
            ExecuteOpen();
            break;
          }
      }
    }

    private void ExecuteClose()
    {
      CancelEventArgs e = new CancelEventArgs();
      OnClosing( e );

      if( !e.Cancel )
      {
        if( !_dialogResult.HasValue )
          _dialogResult = false;

        OnClosed( EventArgs.Empty );
      }
      else
      {
        CancelClose();
      }
    }

    private void CancelClose()
    {
      _dialogResult = null; //when the close is cancelled, DialogResult should be null

      _ignorePropertyChanged = true;
      WindowState = WindowState.Open; //now reset the window state to open because the close was cancelled
      _ignorePropertyChanged = false;
    }

    private void ExecuteOpen()
    {
      _dialogResult = null; //reset the dialogResult to null each time the window is opened

      if( WindowStartupLocation == Xceed.Wpf.Toolkit.WindowStartupLocation.Center )
        CenterChildWindow();

      BringToFront();
    }

    private void BringToFront()
    {
      int index = 0;

      if( _parentContainer != null )
        index = ( int )_parentContainer.GetValue( Canvas.ZIndexProperty );

      SetValue( Canvas.ZIndexProperty, ++index );

      if( IsModal )
        Canvas.SetZIndex( _modalLayerPanel, index - 2 );
    }

    private void CenterChildWindow()
    {
      if( _parentContainer != null )
      {
        Left = ( _parentContainer.ActualWidth - WindowRoot.ActualWidth ) / 2.0;
        Top = ( _parentContainer.ActualHeight - WindowRoot.ActualHeight ) / 2.0;
      }
    }

    private void ShowModalLayer()
    {
      if( !DesignerProperties.GetIsInDesignMode( this ) )
      {
        if( !_modalLayerPanel.Children.Contains( _modalLayer ) )
          _modalLayerPanel.Children.Add( _modalLayer );

        _modalLayer.Visibility = System.Windows.Visibility.Visible;
      }
    }

    private void HideModalLayer()
    {
      _modalLayer.Visibility = System.Windows.Visibility.Collapsed;
    }

    private void ProcessMove( double x, double y )
    {
      _moveTransform.X += x;
      _moveTransform.Y += y;

      InvalidateArrange();
    }

    #endregion //Private

    #region Public

    public void Show()
    {
      WindowState = WindowState.Open;
    }

    public void Close()
    {
      WindowState = WindowState.Closed;
    }

    #endregion //Public

    #endregion //Methods

    #region Events

    /// <summary>
    /// Occurs when the ChildWindow is closed.
    /// </summary>
    public event EventHandler Closed;
    protected virtual void OnClosed( EventArgs e )
    {
      if( Closed != null )
        Closed( this, e );
    }

    /// <summary>
    /// Occurs when the ChildWindow is closing.
    /// </summary>
    public event EventHandler<CancelEventArgs> Closing;
    protected virtual void OnClosing( CancelEventArgs e )
    {
      if( Closing != null )
        Closing( this, e );
    }

    #endregion //Events
  }
}