c# - layered window with blur effect

Question

I really like the effect that can be seen for example in iOS, which basicaly looks like a layer drawn on top of current view , bluring the visual content and using that as a background. Is there a way to achieve something like that in WPF?

I've seen people mostly dealing with this blur/transparency on Window level, but I need it within the window.

Let's say this is the content of my window.

<StackPanel HorizontalAlignment="Center" Orientation="Horizontal">
        <Image  Source="pack://application:,,,/Resources/Penguins.jpg"/>
        <Image  Source="pack://application:,,,/Resources/Penguins.jpg"/>
</StackPanel>

Which looks like

And now I'd like to draw something on top of that which ( instead of using red background ) blures whatever is beneath it and uses it as background, keeping it's content not blury.

    <DockPanel Margin="15" Background="Red">
        <StackPanel Orientation="Horizontal"  VerticalAlignment="Center" HorizontalAlignment="Center">
            <Label Content="Some label"/>
            <TextBox Width="100" Height="20"/>
        </StackPanel>
    </DockPanel>

Answer 1

Result:

• We will use layering in a Grid. Background: Your main application content. Foreground: Your pseudo-dialog that will have a blurred background.

• We will put the background in a border and refer to this border by its name. This will be used in a VisualBrush and provide our to-be-blurred image.

• The foreground will also be a layered grid. Background: A rectangle, filled with the brush and using a blur effect. Foreground: Whatever you want to be in front.

  1. Add a reference to System.Windows.Interactivity.

  2. Add the following behavior code:

     using System;
     using System.Collections.Generic;
     using System.Linq;
     using System.Windows;
     using System.Windows.Controls;
     using System.Windows.Data;
     using System.Windows.Interactivity;
     using System.Windows.Media;
     using System.Windows.Media.Effects;
     using System.Windows.Shapes;
     
     namespace WpfApplication1
     {
         public class BlurBackgroundBehavior : Behavior<Shape>
         {
             public static readonly DependencyProperty BlurContainerProperty
                 = DependencyProperty.Register(
                                               "BlurContainer",
                                               typeof (UIElement),
                                               typeof (BlurBackgroundBehavior),
                                               new PropertyMetadata(OnContainerChanged));
     
             private static readonly DependencyProperty BrushProperty
                 = DependencyProperty.Register(
                                               "Brush",
                                               typeof (VisualBrush),
                                               typeof (BlurBackgroundBehavior), 
                                               new PropertyMetadata());
     
             private VisualBrush Brush
             {
                 get { return (VisualBrush) this.GetValue(BrushProperty); }
                 set { this.SetValue(BrushProperty, value); }
             }
     
             public UIElement BlurContainer
             {
                 get { return (UIElement) this.GetValue(BlurContainerProperty); }
                 set { this.SetValue(BlurContainerProperty, value); }
             }
     
             protected override void OnAttached()
             {
                 this.AssociatedObject.Effect = new BlurEffect
                                                {
                                                    Radius = 80,
                                                    KernelType = KernelType.Gaussian,
                                                    RenderingBias = RenderingBias.Quality
                                                };
     
                 this.AssociatedObject.SetBinding(Shape.FillProperty,
                                                  new Binding
                                                  {
                                                      Source = this,
                                                      Path = new PropertyPath(BrushProperty)
                                                  });
     
                 this.AssociatedObject.LayoutUpdated += (sender, args) => this.UpdateBounds();
                 this.UpdateBounds();
             }
     
             protected override void OnDetaching()
             {
                 BindingOperations.ClearBinding(this.AssociatedObject, Border.BackgroundProperty);
             }
     
             private static void OnContainerChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
             {
                 ((BlurBackgroundBehavior) d).OnContainerChanged((UIElement) e.OldValue, (UIElement) e.NewValue);
             }
     
             private void OnContainerChanged(UIElement oldValue, UIElement newValue)
             {
                 if (oldValue != null)
                 {
                     oldValue.LayoutUpdated -= this.OnContainerLayoutUpdated;
                 }
     
                 if (newValue != null)
                 {
                     this.Brush = new VisualBrush(newValue)
                                  {
                                      ViewboxUnits = BrushMappingMode.Absolute
                                  };
     
                     newValue.LayoutUpdated += this.OnContainerLayoutUpdated;
                     this.UpdateBounds();
                 }
                 else
                 {
                     this.Brush = null;
                 }
             }
     
             private void OnContainerLayoutUpdated(object sender, EventArgs eventArgs)
             {
                 this.UpdateBounds();
             }
     
             private void UpdateBounds()
             {
                 if (this.AssociatedObject != null && this.BlurContainer != null && this.Brush != null)
                 {
                     Point difference = this.AssociatedObject.TranslatePoint(new Point(), this.BlurContainer);
                     this.Brush.Viewbox = new Rect(difference, this.AssociatedObject.RenderSize);
                 }
             }
         }
     }
     

  3. Use it in XAML like this:

     <Grid>
     
         <Border x:Name="content">
             <Border.Background>
                 <ImageBrush ImageSource="bild1.jpg" />
             </Border.Background>
     
             <StackPanel>
                 <TextBox Width="200" Margin="10" />
                 <TextBox Width="200" Margin="10" />
                 <TextBox Width="200" Margin="10" />
             </StackPanel>
         </Border>
     
         <Grid Margin="59,63,46,110"> 
     
             <Rectangle ClipToBounds="True">
                 <i:Interaction.Behaviors>
                     <wpfApplication1:BlurBackgroundBehavior BlurContainer="{Binding ElementName=content}" />
                 </i:Interaction.Behaviors>
             </Rectangle>
     
             <TextBox VerticalAlignment="Center" Text="Blah" Width="200" Height="30" />
     
         </Grid>
     
     </Grid>