wpf TabItem binding IsEnabled

Question

I would like to bind the IsEnabled property of TabItem to data within my code.

e.g. I have a TabItem defined as follows

<TabItem Name="Tab1" Header="Tab1" IsEnabled="{Binding Path=Tab1Enabled, Mode=TwoWay}">
</TabItem>

And I have defined a data class which inherits from INotifyPropertyChanged as follows

class MyData : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
    } 
    public bool Tab1Enabled
    {
        get{ return m_tab1Enabled; }
        set
        {
            m_tab1Enabled = value;
            OnPropertyChanged("Tab1Enabled");
        }
    }            
}

Then I set the DataContext to my data member.

public partial class MyApp : Window
{
    MyData m_myData = new MyData();
    MyApp()
    {
        InitializeComponent();
        this.DataContext = m_myData;
    }
}

However, when the Tab1Enabled property gets set programatically, the PropertyChanged event is null and so the notification event is not sent.

Thanks in advance.

Answer 1

Im guessing you need to change m_bindinData to the variable you want to bind to (m_myData). I fired up VS2012 and tested your code. Setting m_myData.Tab1Enabled = true; set the tab to enabled and setting m_myData.Tab1Enabled = false; disabled it correctly. Heres what I had.

public partial class MyApp : Window
{
    MyData m_myData = new MyData();
    MyApp()
    {
        this.DataContext = m_myData;
        InitializeComponent();

        m_myData.Tab1Enabled = true;
    }
}

class MyData : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
    }
    public bool Tab1Enabled
    {
        get { return m_tab1Enabled; }
        set
        {
            m_tab1Enabled = value;
            OnPropertyChanged("Tab1Enabled");
        }
    }

    private bool m_tab1Enabled;
}

<TabControl>
    <TabItem Name="Tab1" Header="Tab1" IsEnabled="{Binding Path=Tab1Enabled}">
    </TabItem>
    <TabItem Name="Tab2" Header="Tab2">
    </TabItem>
</TabControl>

Answer 2

What about this? Notice the PropertyChangedEventHandler PropertyChanged = PropertyChanged; line in the OnPropertyChanged method.

class MyData : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string name)
    {
        PropertyChangedEventHandler PropertyChanged = PropertyChanged;
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
    } 
    public bool Tab1Enabled
    {
        get{ return m_tab1Enabled; }
        set
        {
            m_tab1Enabled = value;
            OnPropertyChanged("Tab1Enabled");
        }
    }            
}

Answer 3

Your TabItem might not inheriting DataContext of your Window. Try looking into the output window, binding failure error will be there.

As a workaround you can use RelativeSource to travel upto the DataContext of your window and bind with its related property like this -

<TabItem Name="Tab1" Header="Tab1"
         IsEnabled="{Binding Path=DataContext.Tab1Enabled,
                            RelativeSource={RelativeSource Mode=FindAncestor,
                                   AncestorType=Window}, Mode=TwoWay}"/>