Adorner Layer

Loading Adorner

Create an adorner. In C# (LoadingAdorner.cs): 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Documents;
using System.Windows;
using System.Windows.Media;
using System.Threading;
 
namespace LoadingAdorner
{
    /// <summary>
    /// Adorner that disables all controls that fall under it
    /// </summary>
    public class LoadingAdorner : Adorner
    {
        #region Properties
 
        /// <summary>
        /// Gets or sets the color to paint
        /// </summary>
        public Brush Color
        {
            get { return (Brush)GetValue(ColorProperty); }
            set { SetValue(ColorProperty, value); }
        }
 
        /// <summary>
        /// Gets or sets the color to paint
        /// </summary>
        public static readonly DependencyProperty ColorProperty =
            DependencyProperty.Register("Color", typeof(Brush), typeof(LoadingAdorner),
            new PropertyMetadata((Brush)new BrushConverter().ConvertFromString("#7F4047F7")));
 
 
        /// <summary>
        /// Gets or sets the border 
        /// </summary>
        public Pen Border
        {
            get { return (Pen)GetValue(BorderProperty); }
            set { SetValue(BorderProperty, value); }
        }
 
        /// <summary>
        /// Gets or sets the border 
        /// </summary>
        public static readonly DependencyProperty BorderProperty =
            DependencyProperty.Register("Border", typeof(Pen), typeof(LoadingAdorner),
            new UIPropertyMetadata(new Pen(Brushes.Gray, 1)));
 
        //the start point where to start drawing
        private static readonly Point startPoint =
            new Point(0, 0);
 
        /// <summary>
        /// Gets or sets the text to display 
        /// </summary>
        public string OverlayedText
        {
            get { return (string)GetValue(OverlayedTextProperty); }
            set { SetValue(OverlayedTextProperty, value); }
        }
 
        /// <summary>
        /// Gets or sets the text to display 
        /// </summary>
        public static readonly DependencyProperty OverlayedTextProperty =
            DependencyProperty.Register("OverlayedText", typeof(string), typeof(LoadingAdorner), new UIPropertyMetadata(""));
 
        /// <summary>
        /// Gets or sets the foreground to use for the text
        /// </summary>
        public Brush ForeGround
        {
            get { return (Brush)GetValue(ForeGroundProperty); }
            set { SetValue(ForeGroundProperty, value); }
        }
 
        /// <summary>
        /// Gets or sets the foreground to use for the text
        /// </summary>
        public static readonly DependencyProperty ForeGroundProperty =
            DependencyProperty.Register("ForeGround", typeof(Brush), typeof(LoadingAdorner),
            new UIPropertyMetadata(Brushes.Black));
 
 
        /// <summary>
        /// Gets or sets the font size for the text
        /// </summary>
        public double FontSize
        {
            get { return (double)GetValue(FontSizeProperty); }
            set { SetValue(FontSizeProperty, value); }
        }
 
        /// <summary>
        /// Gets or sets the font size for the text
        /// </summary>
        public static readonly DependencyProperty FontSizeProperty =
            DependencyProperty.Register("FontSize", typeof(double), typeof(LoadingAdorner), new UIPropertyMetadata(10.0));
 
 
        /// <summary>
        /// Gets or sets the Typeface for the text
        /// </summary>
        public Typeface Typeface
        {
            get { return (Typeface)GetValue(TypefaceProperty); }
            set { SetValue(TypefaceProperty, value); }
        }
 
        /// <summary>
        /// Gets or sets the Typeface for the text
        /// </summary>
        public static readonly DependencyProperty TypefaceProperty =
            DependencyProperty.Register("Typeface", typeof(Typeface), typeof(LoadingAdorner),
            new UIPropertyMetadata(new Typeface("Verdana")));
 
 
 
        #endregion
 
        /// <summary>
        /// Constructor for the adorner
        /// </summary>
        /// <param name="adornerElement">The element to be adorned</param>
        public LoadingAdorner(UIElement adornerElement)
            : base(adornerElement)
        { }
 
 
        /// <summary>
        /// Called to draw on screen
        /// </summary>
        /// <param name="drawingContext">The drawind context in which we can draw</param>
        protected override void OnRender(System.Windows.Media.DrawingContext drawingContext)
        {
            FormattedText text = new FormattedText(OverlayedText, Thread.CurrentThread.CurrentUICulture,
                FlowDirection.LeftToRight, Typeface, FontSize, ForeGround);
            drawingContext.DrawText(text, startPoint);
            drawingContext.DrawRectangle(Color, Border, new Rect(startPoint, DesiredSize));
            base.OnRender(drawingContext);
        }
    }
}

Get Adorner Layer of a control, then add adorner: 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
 
namespace LoadingAdorner
{
    /// <summary>
    /// Interaction logic for DemoPage.xaml
    /// </summary>
    public partial class DemoPage : Window
    {
        DemoPageController controller = new DemoPageController();
 
        public DemoPage()
        {
            DataContext = controller.Data;
            InitializeComponent();
 
            AttachLoadingAdorner();
        }
 
        private void AttachLoadingAdorner()
        {
            // Create "Loading" adorner
            LoadingAdorner loading = new LoadingAdorner(mainPane);
            loading.FontSize = 15;
            loading.OverlayedText = "loading...";
            loading.Typeface = new Typeface(FontFamily, FontStyles.Italic, 
                FontWeights.Bold, FontStretch);
            Binding bind = new Binding("SearchInProgress");
            bind.Source = controller;
            bind.Converter = new VisibilityConverter();
            loading.SetBinding(LoadingAdorner.VisibilityProperty, bind);
 
            // Get mainPane's AdornerLayer and add new "Loading" adorner
            AdornerLayer.GetAdornerLayer(mainPane).Add(loading);  
        }
    }
 
    /// <summary>
    /// Converter that converts a bool to a Visibility status
    /// </summary>
    public class VisibilityConverter : IValueConverter
    {
        #region IValueConverter Members
 
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return (bool)value ? Visibility.Visible : Visibility.Collapsed;
        }
 
        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
 
        #endregion
    }
 
}
References