CODEWITHSUNDEEP
c#wpf
zulqarnain
zulqarnain

Reputation: 1735

WPF force user to stay on TabItem

Am trying to prevent users from leaving a TabItem until a condition is met. I've implemented code on LostFocus but it keeps firing continuously. I've tried unsubscribing to the event and then subscribing again after setting the TabItem focus. I've also tried setting the TabItem IsSelected true but still none of these work.

private void dataTab_LostFocus(object sender, RoutedEventArgs e)
{
    var result = MessageBox.Show("Do you want to proceed?", "No Option chosen", MessageBoxButton.YesNo, MessageBoxImage.Question);
            if (result == MessageBoxResult.Yes)
                NextTab.Focus();
            else {
                dataTab.LostFocus -= dataTab_LostFocus;
                dataTab.IsSelected = true;
                //Also tried dataTab.Focus();
                //e.Handled = true; Also tried.

                dataTab.LostFocus +=dataTab_LostFocus;
            }
}

Upvotes: 2

Views: 428

Answers (2)

Sinatr
Sinatr

Reputation: 21969

LostFocus is a wrong event, you have to use SelectionChanged of TabControl to prevent tab switching.

Below is a working solution (without MVVM logic may looks obscure). Problem is the lack of SelectionChanging event (before SelectedItem is changed), so you have to remember previously selected item yourself.

xaml:

<TabControl x:Name="tabControl" SelectionChanged="TabControl_SelectionChanged">
    <TabItem x:Name="dataTab" Header="1" /> <!-- the tab with confirmation -->
    <TabItem Header="2" />
    <TabItem Header="3" />
</TabControl>

cs:

object _previous;
void TabControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    var isPreviousWasDataTab = _previous == dataTab;
    _previous = tabControl.SelectedItem; // store SelectedItem for next event
    if (isPreviousWasDataTab && MessageBox.Show("", "", MessageBoxButton.YesNo) != MessageBoxResult.Yes)
        _previous = tabControl.SelectedItem = dataTab;
}

Last line may require a bit explanation:

  1. SelectedItem = dataTab will rise SelectionChanged event;
  2. TabControl_SelectionChanged() will be called;
  3. during that call isPreviousWasDataTab == false, therefore nothing interesting happens;
  4. upon returning we set _previous = dataTab.

Upvotes: 2

JWP
JWP

Reputation: 6963

Wire up an event hanlder to Tabcontrol's Selection changed event.

private void TabControl_SelectionChanged(object sender, SelectionChangedEventArgs e){
//do your filtering here, and set tab control item to the one you want.

Upvotes: 1

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