How to add property MouseDown to existing Attached Property (MVVM)

Question

Hi, I use the following Attached Property for maximize and minimize the window. Now I want to use the property "MouseDown". Can someone show me how to add this property to the existing Attached Property?

 public static readonly DependencyProperty AttPropProperty =
     DependencyProperty.RegisterAttached("AttProp", typeof(bool), typeof(ViewModel), new PropertyMetadata(false, OnPropChanged));
 public static bool GetAttProp(DependencyObject obj) => (bool)obj.GetValue(AttPropProperty);
 public static void SetAttProp(DependencyObject obj, bool par) => obj.SetValue(AttPropProperty, par);
 private static void OnPropChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
 {
   Window w = d as Window;
   if (w == null) return;
   w.Loaded += (s, mbe) => ((ViewModel)(w.DataContext)).Wnd = w;
 }

Answer 1

Hi @Hui Liu-MSFT , The following is the XAML code. I use WindowStyle="None. I want that the window can be moved with the mouse.

<Window x:Class="Win.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:Win"  
        xmlns:vm="clr-namespace:Win.ViewModels.MainWindow"  
        mc:Ignorable="d"  
        Height="450"   
        Width="600"   
        WindowStartupLocation="CenterScreen"   
        Background="White"  
        WindowStyle="None"  
        vm:MainWindowViewModel.AttProp="True">  
      
    <Window.DataContext>  
        <vm:MainWindowViewModel/>  
    </Window.DataContext>  
      
    <Grid>  
        <!--Definition of 3 rows-->  
        <Grid.RowDefinitions >  
            <RowDefinition Height="70"/>  
            <RowDefinition Height="130"/>  
            <RowDefinition Height="*"/>  
        </Grid.RowDefinitions>  
  
        <Button Grid.Row="0"  
                Margin="0,5,5,0"  
                Command="{Binding Cmd}"  
                CommandParameter="Close"/>  
        <Button Grid.Row="0"  
                Margin="0,5,30,0"  
                Command="{Binding Cmd}"  
                CommandParameter="Maximize"/>  
        <Button Grid.Row="0"  
                Margin="0,5,55,0"  
                Command="{Binding Cmd}"  
                CommandParameter="Minimize"/>  
  
    </Grid>  
</Window>  

Answer 2

If you try to move the window through MVVM, it's hard to achieve. It's pure UI logic, not part of the ViewModel. You could refer to the solution here.

You can also see a solution for moving windows with WindowStyle="none" here.

---

If the response is helpful, please click "Accept Answer" and upvote it.
 Note: Please follow the steps in our [documentation][5] to enable e-mail notifications if you want to receive the related email notification for this thread. 

[5]: https://learn.microsoft.com/en-us/answers/articles/67444/email-notifications.html