Binding visibility property

Question

I have gone through several questions regarding this but couldn't get proper answer. I dont know where am wrong with the following code. I am binding visibility property of TextBlock but its not working. Here is my xaml code and am changing visibility property of textblock in button click.

<TextBlock Visibility="{Binding IsVisible}" Text="Visibility Sample" Margin="12,40" HorizontalAlignment="Center" Name="visibilityTextblock"/>
<Button Content="visibility" Tap="Button_Tap_1"/>

Here is my Button_Tap_1 function.

private void Button_Tap_1(object sender, System.Windows.Input.GestureEventArgs e)
    {
            IsVisible = Visibility.Visible;            
    }

Here is my IsVisible Property.

private Visibility _isVisible;
public Visibility IsVisible
    {
        get
        {
            return _isVisible;
        }
        set
        {
            _isVisible = value;
            NotifyPropertyChanged("IsVisible");                
        }
    }

And finally here is my NotifyPropertyChanged Method.

#region NotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(string p)
    {
        if (PropertyChanged == null)
            return;
        PropertyChanged(this, new PropertyChangedEventArgs(p));
    }

#endregion

By default, am initializing Textblock visibility to collapsed by changing its property like,

IsVisible = Visibility.Collapsed; ( in the constructor)

I also derieved from INotifyPropertyChanged Interface and am implementing all these in a same class file. Can anyone help me where am wrong?

Answer 1

Seeing your answer i'm almost sure you didn't implemented INotifyPropertyChanged well. So here is an exemple based on your problem (that works =) ):

Windows : XAML

<Window x:Class="WpfApplication7.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TextBlock Visibility="{Binding IsVisible}" Text="Visibility Sample" Margin="12,40" HorizontalAlignment="Center" Name="visibilityTextblock"/>
        <Button Content="Button" Name="boutontest" HorizontalAlignment="Left" Margin="216,247,0,0" VerticalAlignment="Top" Width="74"/>
    </Grid>
</Window>

Windows : CS

namespace WpfApplication7
{
    /// <summary>
    /// Logique d'interaction pour MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            this.DataContext = new MainViewModel(this);
        }
    }
}

Datacontext :

namespace WpfApplication7
{
    class MainViewModel : ViewModelBase
    {
        private MainWindow mainWindow;

        private Visibility _isVisible = Visibility.Collapsed;
        public Visibility IsVisible
        {
            get
            {
                return _isVisible;
            }
            set
            {
                _isVisible = value;
                OnPropertyChanged("IsVisible");
            }
        }

        public MainViewModel(MainWindow mainWindow)
        {
            this.mainWindow = mainWindow;

            mainWindow.boutontest.Click += BoutonClick;
        }

        private void BoutonClick(object sender, RoutedEventArgs e)
        {
            IsVisible = Visibility.Visible;
        }
    }
}

Implementation of INotifyPropertyChanged

namespace WpfApplication7
{
    public abstract class ViewModelBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}