LabelProperties do not listen on property change when DataContext is set after InitializeComponent

[Robert]

If i have a trigger on IsEnabled in my LabelProperties style an bind that to a DependecyProperty in my ViewModel the Trigger will not 'fire' when i set the DataContext after InitilizeComponent only if i set it before. The problem with this is that IsEnable will  not work if i set the DataContext in xaml on a UserControl containing the gauge. I think that this is a faulty behavior because Minor/MajorTickStyle works if i set the DataContext after InitilizeComponent.

well this thread is useless without code so...

my usercontrol

<UserControl x:Class="WpfTest_Telerik.UserControl1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
    Width="300" Height="300">
    <UserControl.Resources>

        <Style x:Key="MajorTickStyle" TargetType="{x:Type telerik:TickProperties}">
            <Setter Property="Background" Value="White" />
            <Style.Triggers>
                <Trigger Property="IsEnabled" Value="False">
                    <Setter Property="Background" Value="Black" />
                </Trigger>
            </Style.Triggers>
        </Style>

        <Style x:Key="LabelProperties" TargetType="{x:Type telerik:LabelProperties}">
            <Setter Property="Foreground" Value="White" />
            <Style.Triggers>
                <Trigger Property="IsEnabled" Value="False">
                    <Setter Property="Foreground" Value="Black" />
                </Trigger>
            </Style.Triggers>
        </Style>

    </UserControl.Resources>
    <Grid>
        <telerik:RadGauge>
            <telerik:RadialGauge>
                <telerik:RadialScale>
                    <telerik:RadialScale.MajorTick>
                        <telerik:TickProperties IsEnabled="{Binding Path=IsActive}" Style="{StaticResource MajorTickStyle}"/>
                    </telerik:RadialScale.MajorTick>
                    <telerik:RadialScale.Label >
                        <telerik:LabelProperties IsEnabled="{Binding Path=IsActive}"  Style="{StaticResource LabelProperties}" />
                    </telerik:RadialScale.Label>
                </telerik:RadialScale>
            </telerik:RadialGauge>
        </telerik:RadGauge>
    </Grid>
</UserControl>

code behind

using System.Windows.Controls;

namespace WpfTest_Telerik
{
    /// <summary>
    /// Interaction logic for UserControl1.xaml
    /// </summary>
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            // will work
            //DataContext = new UserControl1ViewModel();
            InitializeComponent();
            // will not work
            DataContext = new UserControl1ViewModel();
        }
    }
}

my viewmodel

using System;
using System.Windows;
using System.Timers;
using System.Windows.Threading;

namespace WpfTest_Telerik
{
    public class UserControl1ViewModel : DependencyObject
    {
        private readonly Dispatcher _currentDispatcher;

        public UserControl1ViewModel()
        {
            _currentDispatcher = Dispatcher.CurrentDispatcher;

            var timer = new Timer(2000);
            timer.Elapsed += TimerElapsed;
            timer.Start();
        }

        void TimerElapsed(object sender, ElapsedEventArgs e)
        {
            Action x = () => IsActive = !IsActive;

            _currentDispatcher.BeginInvoke(x);
        }

        public bool IsActive
        {
            get { return (bool)GetValue(IsActiveProperty); }
            set { SetValue(IsActiveProperty, value); }
        }

        // Using a DependencyProperty as the backing store for IsActive.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty IsActiveProperty =
                DependencyProperty.Register("IsActive", typeof(bool), typeof(UserControl1ViewModel), new UIPropertyMetadata(false));
    }
}

[Andrey]

Hi Robert,

It seems there is a problem in using of data context inheritance with other inheritable properties like to the Foreground or font related properties.
I think as workaround you could use a binding to setup the data context for gauge labels.
As sample you could add the following setter to your LabelProperties style:
<Setter Property="DataContext" Value="{Binding}" />

Kind regards,
Andrey Murzov
the Telerik team

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[Robert]

Works like a charm now, thanks!