wpf - mvvm - listbox - IsEnabled

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• Saturday, November 07, 2009 11:53 AMOlaf Rabbachin

   
  

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  Hi Yehuda,
  
  to make this work, you'll have to notify the View that the isProductListEnabled property has changed. To do so, implement INotifyPropertyChanged in your ViewModel. Here's a sample that shows how to work this out; I didn't follow MVVM here for the sake of simplicity:
  
  

  <Window x:Class="WpfTests.ListBoxIsEnabled"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     Title="ListBoxIsEnabled" Height="300" Width="300"
     DataContext="{Binding RelativeSource={RelativeSource Self}}"
     >
  
     <Grid>
        <Grid.RowDefinitions>
           <RowDefinition Height="Auto"/>
           <RowDefinition Height="*"/>
           <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Button Grid.Row="0" Content="Toggle ListBox'es IsEnabled-prop" Click="Button_Click" Margin="5" Padding="5"/>
        <ListBox Grid.Row="1" Foreground="OrangeRed" IsEnabled="{Binding IsListBoxEnabled}" Margin="5" SelectedIndex="0">
           <ListBoxItem Content="Item1"/>
           <ListBoxItem Content="Item2"/>
        </ListBox>
        <CheckBox Grid.Row="2" Content="ListBox is enabled" IsChecked="{Binding IsListBoxEnabled}" Margin="5"/>
     </Grid>
  </Window>
  
  

  
  And the code-behind:
  
  

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  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.Shapes;
  using System.ComponentModel;
  
  namespace WpfTests
  {
     /// <summary>
     /// Interaction logic for ListBoxIsEnabled.xaml
     /// </summary>
     public partial class ListBoxIsEnabled : Window, INotifyPropertyChanged
     {
  
        private bool _fIsListBoxEnabled = true;
        public bool IsListBoxEnabled
        {
           get { return _fIsListBoxEnabled; }
           set
           {
              _fIsListBoxEnabled = value;
              OnPropertyChanged("IsListBoxEnabled");
           }
        }
  
        private void Button_Click(object sender, RoutedEventArgs e)
        {
           IsListBoxEnabled = !IsListBoxEnabled;
        }
  
        public ListBoxIsEnabled()
        {
           InitializeComponent();
        }
  
  
        #region INotifyPropertyChanged Members
  
        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string prop)
        {
           if (PropertyChanged != null)
           {
              PropertyChanged(this, new PropertyChangedEventArgs(prop));
           }
        }
  
        #endregion
  
     }
  }
  
  

  
  
  

  ---

  Cheers,
  Olaf

  • Marked As Answer byLinda LiuMSFT, ModeratorFriday, November 13, 2009 10:26 AM
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• Saturday, November 07, 2009 6:15 PMYehuda A

   
  

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  Olaf
  Thank you very much
  It's working!
  
  Apparently I was only missing this line:
  OnPropertyChanged("IsListBoxEnabled");
   (in the 'set' of  IsListBoxEnabled property...)
  
  b.t.w. just for general knowledge,
  could I use for the same scenario with DependencyProperty?
  
  Again,
  Thanks - Yehuda
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• Sunday, November 08, 2009 12:14 PMOlaf Rabbachin

   
  

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  Hi Yehuda,
  
  yes, that'd be an alternative approach. Just replace the code-behind of my previous sample with this one here:
  
  

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  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.Shapes;
  
  namespace WpfTests
  {
     /// <summary>
     /// Interaction logic for ListBoxIsEnabled.xaml
     /// </summary>
     public partial class ListBoxIsEnabled : Window
     {
        public static DependencyProperty IsListBoxEnabledProperty =
           DependencyProperty.Register(
                 "IsListBoxEnabled",
                 typeof(bool),
                 typeof(ListBoxIsEnabled)
              );
  
        public bool IsListBoxEnabled
        {
           get { return (bool)GetValue(IsListBoxEnabledProperty); }
           set { SetValue(IsListBoxEnabledProperty, value); }
        }
  
        private void Button_Click(object sender, RoutedEventArgs e)
        {
           IsListBoxEnabled = !IsListBoxEnabled;
        }
  
        public ListBoxIsEnabled()
        {
           InitializeComponent();
        }
     }
  }
  
  

  
  
  

  ---

  Cheers,
  Olaf

  • Marked As Answer byYehuda A Saturday, November 21, 2009 5:20 PM
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