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POWindows Phone data binding: cross-thread
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  1. POWindows Phone data binding: cross-thread
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    copied!<p>we have a problem with data binding on windows phone (using xaml). i have created a simple example, which should allow to reproduce the problem. Here is our model-class:</p> <pre><code>public class Data : INotifyPropertyChanged { private int value = 0; public int Value { get { return value; } set { this.value = value; if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs("Value")); } } } public event PropertyChangedEventHandler PropertyChanged; public Data() { var t = new Thread(new ThreadStart(() =&gt; { while (true) { Thread.Sleep(2000); Value += 1; } })); t.IsBackground = true; t.Start(); } } </code></pre> <p>which uses a thread to update the value-property and fire the PropertyChanged-event.</p> <p>Now i want to bind this value-property to a gui control:</p> <pre><code> &lt;Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0"&gt; &lt;TextBlock Text="{Binding Path=Value}" /&gt; &lt;/Grid&gt; public MainPage() { InitializeComponent(); DataContext = new Data(); } </code></pre> <p>when the value first changes (and the PropertyChanged-event gets fired) the data binding system tries to copy the value of Data.Value to TextBlock.Text, which results in an invalid cross-thread exception, as this event is not fired on the ui thread.</p> <p>my question: shouldn't the .NET databinding framework recognize that i'm binding to a ui control and perform the thread switching itself? i know that i can simply use a dispatcher to fire the PropertyChanged-event on the main thread, but i'd like to have my model-class more seperated from the gui component. is there a better solution to this problem? i am unable to use the DependencyObject approach, because our core project (which contains the model class) should run on Windows Phone AND Android, and Android doesn't support the System.Windows-namespace.</p>
 

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