Question

A have ListBox and 4 Items.
2 visible
2 colpased:

Click:

-this bad!

I need this:

I need Set in reapeatButton change Interval!?!? how to do it

Answer 1

What you want is for the list box to scroll by two lines for every one time you click the repeat buttons. Here is a behavior that you can add to your ListBox that will do just that.

First add this namespace:

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

and the corresponding reference to your project.

Then the XAML looks like this:

<ListBox ScrollViewer.VerticalScrollBarVisibility="Visible" Height="40">
    <i:Interaction.Behaviors>
        <local:ScrollBehavior LineMultiplier="2"/>
    </i:Interaction.Behaviors>
    <ListBoxItem Content="Item1"/>
    <ListBoxItem Content="Item2"/>
    <ListBoxItem Content="Item3"/>
    <ListBoxItem Content="Item4"/>
</ListBox>

and here is the behavior:

class ScrollBehavior : Behavior<FrameworkElement>
{
    public int LineMultiplier
    {
        get { return (int)GetValue(LineMultiplierProperty); }
        set { SetValue(LineMultiplierProperty, value); }
    }

    public static readonly DependencyProperty LineMultiplierProperty =
        DependencyProperty.Register("LineMultiplier", typeof(int), typeof(ScrollBehavior), new UIPropertyMetadata(1));

    protected override void OnAttached()
    {
        AssociatedObject.Loaded += new RoutedEventHandler(AssociatedObject_Loaded);
    }

    private ScrollViewer scrollViewer;

    private void AssociatedObject_Loaded(object sender, RoutedEventArgs e)
    {
        scrollViewer = GetScrollViewer(AssociatedObject);
        scrollViewer.CommandBindings.Add(new CommandBinding(ScrollBar.LineUpCommand, LineCommandExecuted));
        scrollViewer.CommandBindings.Add(new CommandBinding(ScrollBar.LineDownCommand, LineCommandExecuted));
    }

    private void LineCommandExecuted(object sender, ExecutedRoutedEventArgs e)
    {
        if (e.Command == ScrollBar.LineUpCommand)
        {
            for (int i = 0; i < LineMultiplier; i++)
                scrollViewer.LineUp();
        }

        if (e.Command == ScrollBar.LineDownCommand)
        {
            for (int i = 0; i < LineMultiplier; i++)
                scrollViewer.LineDown();
        }
    }

    private ScrollViewer GetScrollViewer(DependencyObject o)
    {
        if (o is ScrollViewer)
            return o as ScrollViewer;
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(o); i++)
        {
            var result = GetScrollViewer(VisualTreeHelper.GetChild(o, i));
            if (result != null)
                return result;
        }
        return null;
    }
}