How to disable and enable window close button [X] in MVVM?

Question

Dear all,

I need to disable and enable the Windows [X] close button using the Binding (Mvvm).

How can I do ?

Best Regards

Answer 1

Here is an example of disabling and enabling the close button.
MainWindow.xaml:

<Grid>  
        <ToggleButton x:Name="tb" Width="100" Height="40"  Click="tb_Click">  
            <ToggleButton.Style>  
                <Style TargetType="ToggleButton">  
                    <Style.Triggers>  
                        <Trigger Property="IsChecked" Value="True">  
                            <Setter Property="Content" Value="enable"/>  
                        </Trigger>  
                        <Trigger Property="IsChecked" Value="False">  
                            <Setter Property="Content" Value="disable"/>  
                        </Trigger>  
                    </Style.Triggers>  
                </Style>  
            </ToggleButton.Style>  
        </ToggleButton>  
    </Grid>  

MainWindow.xaml.cs:

using System;  
using System.Runtime.InteropServices;  
using System.Windows;  
using System.Windows.Controls.Primitives;  
using System.Windows.Interop;  
  
public partial class MainWindow : Window  
  {  
    public MainWindow()  
    {  
      InitializeComponent();  
    }  
    [DllImport("user32.dll")]  
    static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);  
    [DllImport("user32.dll")]  
    static extern bool EnableMenuItem(IntPtr hMenu, uint uIDEnableItem, uint uEnable);  
  
    const uint MF_GRAYED = 0x00000001;  
    const uint MF_ENABLED = 0x00000000;  
    const uint SC_CLOSE = 0xF060;  
      
    private void tb_Click(object sender, RoutedEventArgs e)  
    {  
      var tb = sender as ToggleButton;  
      if ((bool)tb.IsChecked)  
      {  
        var hwnd = new WindowInteropHelper(this).Handle;  
        IntPtr hMenu = GetSystemMenu(hwnd, false);  
        EnableMenuItem(hMenu, SC_CLOSE, MF_GRAYED);  
      }  
      else  
      {  
        var hwnd = new WindowInteropHelper(this).Handle;  
        IntPtr hMenu = GetSystemMenu(hwnd, false);  
        EnableMenuItem(hMenu, SC_CLOSE, MF_ENABLED);  
      }  
    }  
  }  

The result:

Edit:

public partial class MainWindow : Window  
  {   
    ViewModel vm ;  
    public MainWindow()  
    {  
      InitializeComponent();  
      vm=new ViewModel();  
      DataContext=vm;  
      this.Closing += new CancelEventHandler(Window_Closing);  
    }  
    void Window_Closing(object sender, CancelEventArgs e)  
    {  
      e.Cancel = (this.DataContext as ViewModel).ProcessWorking;  
    }  
  
    private void btn_Click(object sender, RoutedEventArgs e)  
    {  
      var tb = sender as ToggleButton;  
      if ((bool)tb.IsChecked)  
      {  
        vm.ProcessWorking = true;  
      }  
      else  
      {  
        vm.ProcessWorking = false;  
      }  
    }  
  }  
  public class ViewModel:INotifyPropertyChanged  
  {  
    private bool processWorking=false;  
    public bool ProcessWorking  
    {  
      get { return this.processWorking; }  
      set  
      {  
        this.processWorking=value;  
        OnPropertyChanged("ProcessWorking");  
      }  
    }  
    protected void OnPropertyChanged([CallerMemberName] string name = null)  
    {  
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));  
    }  
    public event PropertyChangedEventHandler PropertyChanged;  
  }  

The result:

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Answer 2

it would depend on the MVVM framework used.

it requires an O/S call and the window handle to disable the window close button. also it is not recommended.