WPF hides line, but does not sweep white space

You can use Data Binding and bind the Visibility

control property inside the string you want to collapse with the converter.

I usually use the Mvvm Light NuGet package , documentation , to have some functionality when using data binding. (In this case, the implementation RelayCommand

, RaisePropertyChanged

)

The simplest example:

Part of the review. Here you can notice the binding between the Visibility

button property and the property IsButton1Visible

ViewModel

. Of course, bool

and Visibility

are not the same type, so I had to create a mapping using IValueConverter

:

 <Grid>

    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>

    <Button Grid.Row="0" Content="1" Visibility="{Binding IsButton1Visible, Converter={StaticResource BooleanToVisibilityConverter}}" />
    <Button Grid.Row="1" Content="2" />
    <Button Grid.Row="2" Content="3" />
    <Button Grid.Row="3" Content="4" />
    <Button Grid.Row="4" Content="Toggle button 1 visibility" Command="{Binding ToggleButton1Visibility}" />

</Grid>

      

        
        
        
      

    

The window constructor in the code behind (you can also bind ViewModel

with a property DataContext

directly in View

), used to bind View

with ViewModel

:

public MainWindow()
{
    InitializeComponent();
    this.DataContext = new MyWindowViewModel();
}

      

        
        
        
      

    

Converter to convert true

to Visibility.Visible

:

public class BooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        => (bool)value ? Visibility.Visible : Visibility.Collapsed;

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

      

        
        
        
      

    

App.xaml

, the Application.Resource

part used to convert the View

"to" converter:

<Application.Resources>

    <local:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />

</Application.Resources>

      

        
        
        
      

    

ViewModel. The RaisePropertyChanged

method is set

IsButton1Visible

very important here because it notifies View

that the property has changed, so it View

can update itself:

public class MyWindowViewModel : ViewModelBase
{
    private bool _isButton1Visibile = true;
    public bool IsButton1Visible
    {
        get => _isButton1Visibile;
        set
        {
            if (_isButton1Visibile == value)
                return;

            _isButton1Visibile = value;
            RaisePropertyChanged(nameof(IsButton1Visible));
        }
    }


    RelayCommand _toggleButton1Visbility;
    public RelayCommand ToggleButton1Visibility
    {
        get
        {
            return _toggleButton1Visbility ?? (_toggleButton1Visbility = new RelayCommand(
                () =>
                {
                    IsButton1Visible = !IsButton1Visible;
                }));
        }
    }
}