using System;

 using System.Collections.Generic;

 using System.Linq;

 using System.Text;

 using System.Threading.Tasks;

 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.Navigation;

 using System.Windows.Shapes;

 namespace WpfApplication1

 {

     /// <summary>

     /// MainWindow.xaml 的交互逻辑

     /// </summary>

     public partial class MainWindow : Window

     {

         public MainWindow()

         {

             InitializeComponent();

             Binding binding = new Binding();

             binding.Source = main_grid;

             binding.Path = new PropertyPath("Margin");

             binding.Mode = BindingMode.TwoWay;

             binding.Converter = new MarginConverter();

             binding.ConverterParameter = main_grid.Width;

             sub_grid.SetBinding(Grid.MarginProperty, binding);

         }

         public class MarginConverter : IValueConverter

         {

             public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)

             {

                 Thickness margin = (Thickness)value;

                 double width = (double)parameter;

                 return new Thickness(margin.Left + width, margin.Top -, , );

             }

             public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)

             {

                 Thickness margin = (Thickness)value;

                 double width = (double)parameter;

                 return new Thickness(margin.Left - width, margin.Top + , , );

             }

         }

         //选中控件的鼠标位置偏移量

         Point targetPoint;

         private void canvas_MouseDown(object sender, MouseButtonEventArgs e)

         {

             var targetElement = e.Source as IInputElement;

             if (targetElement != null)

             {

                 targetPoint = e.GetPosition(targetElement);

                 //开始捕获鼠标

                 targetElement.CaptureMouse();

             }

         }

         private void canvas_MouseUp(object sender, MouseButtonEventArgs e)

         {

             //取消捕获鼠标

             Mouse.Capture(null);

         }

         private void canvas_MouseMove(object sender, MouseEventArgs e)

         {

             //确定鼠标左键处于按下状态并且有元素被选中

             var targetElement = Mouse.Captured as Grid;

             if (e.LeftButton == MouseButtonState.Pressed && targetElement != null)

             {

                 var pCanvas = e.GetPosition(canvas);

                 //设置最终位置

                 targetElement.Margin = new Thickness(pCanvas.X - targetPoint.X, pCanvas.Y - targetPoint.Y, , );

             }

         }

     }

 }

 <Window x:Class="WpfApplication1.MainWindow"

         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:WpfApplication1"

         mc:Ignorable="d"

         Title="MainWindow" Height="350" Width="525">

     <Canvas>

         <Viewbox Stretch="Fill">

             <Grid x:Name="canvas" Height="350" Width="525">

                 <Grid x:Name="main_grid" Height="50" Width="80" Background="Yellow" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="100,100,0,0" PreviewMouseMove="canvas_MouseMove" PreviewMouseLeftButtonDown="canvas_MouseDown" PreviewMouseLeftButtonUp="canvas_MouseUp">

                     <Border BorderBrush="Black" BorderThickness="1" ></Border>

                 </Grid>

                 <Grid x:Name="sub_grid" Height="30" Width="30" Background="LightBlue" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="180,70,0,0" PreviewMouseMove="canvas_MouseMove" PreviewMouseLeftButtonDown="canvas_MouseDown" PreviewMouseLeftButtonUp="canvas_MouseUp">

                     <Border BorderBrush="Black" BorderThickness="1"></Border>

                 </Grid>

             </Grid>

         </Viewbox>

     </Canvas>

 </Window>