勾選/取消勾選複選框時啓用，禁用按鈕

我有一個視圖，其中包含按鈕形式的各種項目和每個按鈕的複選框。 XAML：勾選/取消勾選複選框時啓用，禁用按鈕

 <ListBox.ItemTemplate> 
      <DataTemplate> 
       <Grid> 
        <Grid.ColumnDefinitions> 
         <ColumnDefinition /> 
         <ColumnDefinition /> 
        </Grid.ColumnDefinitions> 
        <CheckBox x:Name="CheckFavorite" 
           Width="Auto" 
           Height="Auto" 
           AutomationProperties.AutomationId="AID_FavoritesCheck" 
           IsChecked="{Binding Path=IsChecked, 
                Mode=TwoWay}" 
           Visibility="{Binding IsFavoriteConfiguredAndInDA, 
                Converter={StaticResource boolToVisibility}}" 
           Checked="OnContentChanged" 
           Unchecked="OnContentChanged"/> 
        <Button Grid.Column="1" 
          Width="240" 
          HorizontalContentAlignment="Left" 
          VerticalContentAlignment="Center" 
          AutomationProperties.AutomationId="AID_BtnLaunchFavorite" 
          Command="{Binding Path=LaunchFavorite}" 
          Content="{Binding Path=ModuleDisplayName}" 
          Cursor="Hand" 
          FontSize="{StaticResource UxLevel_5}" 
          Padding="24 12 2 12" 
          ToolTip="{Binding Path=ModuleDisplayName}" /> 
       </Grid> 
      </DataTemplate> 
     </ListBox.ItemTemplate>

我有另一個叫做「Launch」的按鈕。它的基本功能是發射任務按選擇在上面的列表框項目，使多個任務可以launched.Button XAML：

 <Button Name="btnLaunch" 
       Width="80" 
       Height="25" 
       HorizontalAlignment="Left" 
       AutomationProperties.AutomationId="AUI_BtnLaunchForFavorite" 
       Command="{Binding LaunchCommand}" 
       Style="{StaticResource LaunchButtonStyle}" 
       Visibility="{Binding IsRIAMode, 
            Converter={StaticResource boolToVisibilityInverter}}">

問題：我想啓用/如果ATLEAST一個禁用此啓動按鈕項目被選中並禁用其他方式。我可以如何實現？請幫助一些代碼片段。

UPDATE：這裏是啓動命令：

public ICommand LaunchCommand { get; private set; } 
LaunchCommand = new DelegateCommand<object>(OnLaunch); 
     internal void OnLaunch(object sender) 
     { 
      var nFavItemToLaunchCount = Favorites.Count(favItem => favItem.IsChecked); 

      if (!IsSessionLimitReached(nFavItemToLaunchCount)) 
      { 
       foreach (FavoriteItemViewModel favoriteItem in Favorites) 
       { 
        if (favoriteItem.IsChecked) 
        { 
         favoriteItem.LaunchFavorite.Execute(sender); 

        } 
       } 
      } 
     }

更新2：

我所做的更改按克里希納的評論：

LaunchCommand = new DelegateCommand<object>(OnLaunch,ToggleLaunch); 
private bool ToggleLaunch(object obj) 
{ 

     if (Favorites.Count(i => i.IsChecked)!=0) //Favorites is the itemsource 
     { 
       return true; 
     } 
      return false; 
}

儘管如此發射按鈕顯示禁用即使在選擇/檢查項目時也是如此。

更新3

Krishna的進一步的評論之後，我改變了性質的器isChecked實施以及在實施viewmodel.Still沒有INotifyPropertyChanged的運氣！

public class FavoriteItemViewModel:INotifyPropertyChanged 
{ 
     public bool IsChecked 
     { 
      get 
      { 
       return m_IsChecked; 
      } 
      set 
      { 
       m_IsChecked = value; 
       OnPropertyChanged("IsChecked"); 
      } 
     } 

     /// <summary> 
     /// Handler for property change 
     /// </summary> 
     /// <param name="propertyName">Name of property</param> 
     protected void OnPropertyChanged(string propertyName) 
     { 
      PropertyChangedEventHandler handler = PropertyChanged; 

      if (handler != null) 
      { 
       handler(this, new PropertyChangedEventArgs(propertyName)); 
      } 
     } 
}

還有另一種視圖模型「FavoriteContainerViewModel」持有「FavoriteItemViewModel」的集合，也實現INotifyPropertyChanged。此容器視圖模型是其中i加入UPDATE提到的代碼的地點2

UPDATE 4：執行收藏：

public class FavoriteContainerViewModel : ViewModelBase, IModuleView 
{ 
    private readonly ObservableCollection<FavoriteItemViewModel> m_Favorites = new ObservableCollection<FavoriteItemViewModel>(); 

     public ObservableCollection<FavoriteItemViewModel> Favorites 
     { 
      get { return m_Favorites; } 
     } 
     public FavoriteContainerViewModel() 
     { 
      LaunchCommand = new DelegateCommand<object>(OnLaunch, ToggleLaunch); 
      OnLoad(); 
     } 
     private bool ToggleLaunch(object obj) 
     { 
      if (Favorites.Count(i => i.IsChecked) != 0) 
      { 
       return true; 
      } 
      return false; 
      //return true; 
     } 
}

注：ViewModelBase實現INotifyPropertyChanged

更新5：問題現在使用基於事件的模型解決。實現以下幾點： FavoriteViewModel.cs

public event EventHandler ItemChecked; 
public bool IsChecked 
{ 
    get 
    { 
     return m_IsChecked; 
    } 
    set 
    { 
     m_IsChecked = value; 
     if (ItemChecked != null) 
     { 
      ItemChecked(this, new EventArgs()); 
     } 
    } 
}

FavoriteItemContainerViewModel.cs

private void SubscribeFavoriteItemEvents(FavoriteItemViewModel favorite) 
{ 
    favorite.ItemChecked += ToggleLaunchButton; 
} 

private bool m_IsLaunchEnabled; 
public bool IsLaunchEnabled 
{ 
    get 
    { 
     return m_IsLaunchEnabled; 
    } 
    set 
    { 
     m_IsLaunchEnabled = value; 
     OnPropertyChanged("IsLaunchEnabled"); 
    } 
}

物業IsLaunchEnabled被綁定到按鈕啓用/禁用。

來源

2014-05-14 Sandeep

什麼是'LaunchCommand'？ – amnezjak

單擊此按鈕啓動LaunchCommand並啓動選定的任務。 – Sandeep

是的，但是它的實例是什麼類？你自己的'ICommand'實現還是一些工具包類？你有'CanExecute'方法嗎？如果是這樣，啓用/禁用該方法中的按鈕。 – amnezjak

勾選/取消勾選複選框時啓用，禁用按鈕

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