原始碼已封裝成 MirrorGrid類 可以直接在XAML裡新增

根據需要可以把Grid 改為  button border等控制元件

注意 Target必須為當前控制元件下層的控制元件物件

加個BlurEffect就是毛玻璃效果

<!--玻璃層控制元件-->
        <local:MirrorGrid
            Background="Red"
            Target="{Binding ElementName=box}"
            Width="150"
            Height="100"
            x:Name="thumb" Margin="0,0,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" MouseDown="thumb_MouseDown" MouseMove="thumb_MouseMove" MouseUp="thumb_MouseUp">
            <local:MirrorGrid.Effect>
                <BlurEffect  Radius="20" RenderingBias="Performance"/>
            </local:MirrorGrid.Effect>
        </local:MirrorGrid>
 

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

namespace WpfApp2
{
    /// <summary>
    /// 映象格子
    /// </summary>
    public class MirrorGrid : Grid
    {

        /// <summary>
        /// 目標物件
        /// </summary>
        public FrameworkElement Target
        {
            get { return (FrameworkElement)GetValue(TargetProperty); }
            set { SetValue(TargetProperty, value); }
        }

        /// <summary>
        /// 目標物件屬性
        /// </summary>
        public static readonly DependencyProperty TargetProperty =
        DependencyProperty.Register("Target", typeof(FrameworkElement), typeof(MirrorGrid),
        new FrameworkPropertyMetadata(null));

        /// <summary>
        /// 重寫基類 Margin
        /// </summary>
        public new Thickness Margin
        {
            get { return (Thickness)GetValue(MarginProperty); }
            set { SetValue(MarginProperty, value); }
        }
        public new static readonly DependencyProperty MarginProperty = DependencyProperty.Register("Margin", typeof(Thickness), typeof(MirrorGrid), new FrameworkPropertyMetadata(new Thickness(0), new PropertyChangedCallback(OnMarginChanged)));
        private static void OnMarginChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
        {
            ((FrameworkElement)target).Margin = (Thickness)e.NewValue;
            //強制渲染
            ((FrameworkElement)target).InvalidateVisual();
        }

        protected override void OnRender(DrawingContext dc)
        {
            var Rect = new Rect(0, 0, RenderSize.Width, RenderSize.Height);
            if (Target == null)
            {
                dc.DrawRectangle(this.Background, null, Rect);
            }
            else
            {
                this.DrawImage(dc, Rect);
            }

        }

        private void DrawImage(DrawingContext dc, Rect rect)
        {
            VisualBrush brush = new VisualBrush(Target)
            {
                Stretch = Stretch.Fill,
            };
            var tl = this.GetElementLocation(Target);
            var sl = this.GetElementLocation(this);
            var lx = (sl.X - tl.X) / Target.ActualWidth;
            var ly = (sl.Y - tl.Y) / Target.ActualHeight;
            var pw = this.ActualWidth / Target.ActualWidth;
            var ph = this.ActualHeight / Target.ActualHeight;
            brush.Viewbox = new Rect(lx, ly, pw, ph);
            dc.DrawRectangle(brush, null, rect);
        }


        /// <summary>
        /// 獲取控制元件元素在視窗的實際位置
        /// </summary>
        /// <param name="Control"></param>
        /// <returns></returns>
        public Point GetElementLocation(FrameworkElement Control)
        {
            Point location = new Point(0, 0);
            FrameworkElement element = Control;
            while (element != null)
            {
                var Offset = VisualTreeHelper.GetOffset(element);
                location = location + Offset;
                element = (FrameworkElement)VisualTreeHelper.GetParent(element);
            }
            return location;
        }

    }
}
 

測試原始碼

<Window x:Class="WpfApp2.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp2"
        mc:Ignorable="d"
        Title="Window1" Height="450" Width="800">
    <Grid ClipToBounds="True">
        <!--下層被模糊層-->
        <Grid x:Name="box"
              Background="AntiqueWhite"
              HorizontalAlignment="Left" Height="332" VerticalAlignment="Top" Width="551">
            <Grid HorizontalAlignment="Left" Height="260" Margin="0,0,0,0" VerticalAlignment="Top" Width="345">
                <Grid.Background>
                    <ImageBrush ImageSource="123.png"/>
                </Grid.Background>
            </Grid>
            <Ellipse Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="114" Margin="345,218,0,0" Stroke="Black" VerticalAlignment="Top" Width="206"/>
        </Grid>
        <!--玻璃層控制元件-->
        <local:MirrorGrid
            Background="Red"
            Target="{Binding ElementName=box}"
            Width="150"
            Height="100"
            x:Name="thumb" Margin="0,0,0,0" HorizontalAlignment="Left" VerticalAlignment="Top" MouseDown="thumb_MouseDown" MouseMove="thumb_MouseMove" MouseUp="thumb_MouseUp">
            <local:MirrorGrid.Effect>
                <BlurEffect  Radius="20" RenderingBias="Performance"/>
            </local:MirrorGrid.Effect>
        </local:MirrorGrid>
        <!--測試邊框線-->
        <Rectangle Stroke="#FF2DEC0E"  
                   IsHitTestVisible="False"
                   Width="{Binding ElementName=thumb, Path=Width}"
                   Height="{Binding ElementName=thumb, Path=Height}"
                   Margin="{Binding ElementName=thumb, Path=Margin}"
                   HorizontalAlignment="Left" VerticalAlignment="Top"/>


    </Grid>
</Window>
 

後臺

using System.Windows;
using System.Windows.Input;

namespace WpfApp2
{
    /// <summary>
    /// Window1.xaml 的互動邏輯
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }


        private bool isDragging;
        private Point clickPosition;

        private void thumb_MouseDown(object sender, MouseButtonEventArgs e)
        {
            isDragging = true;
            var draggableElement = sender as UIElement;
            clickPosition = e.GetPosition(this);
            draggableElement.CaptureMouse();
        }

        private void thumb_MouseUp(object sender, MouseButtonEventArgs e)
        {
            isDragging = false;
            var draggableElement = sender as UIElement;
            draggableElement.ReleaseMouseCapture();
        }

        private void thumb_MouseMove(object sender, MouseEventArgs e)
        {
            var draggableElement = sender as UIElement;
            if (isDragging && draggableElement != null)
            {
                Point currentPosition = e.GetPosition(this.Parent as UIElement);
                Thickness s = new Thickness(thumb.Margin.Left + currentPosition.X - clickPosition.X, thumb.Margin.Top + currentPosition.Y - clickPosition.Y,0,0);
                thumb.Margin = s;
                clickPosition = currentPosition;
            }
        }



    }
}