CODEWITHSUNDEEP
c#wpfmultithreadingbackgroundworker
jason
jason

Reputation: 7164

"Must create DependencySource on same Thread as the DependencyObject." when binding Background

I want to change a label and background of a datagrid inside a Backgroundworker. I have Grid like this : 

<Grid HorizontalAlignment="Center" Height="499" Margin="96,170,810,0" VerticalAlignment="Top" Width="486" Background="{Binding aBackGround}">
    <Label Content="212" FontSize="100"  HorizontalAlignment="Left" VerticalAlignment="Top" RenderTransformOrigin="-4.395,-11.154" Margin="173,22,0,0" Height="123" Width="178"/>
    <Label Content="{Binding aPace}" FontSize="65"  HorizontalAlignment="Left" VerticalAlignment="Top" Margin="23,202,0,0" Height="84" Width="255"/>
</Grid>

In code behind I have aBackGround and aPace like this: 

private Brush _aBackGround;
private string _apace;

public Brush aBackGround
{
    get { return _aBackGround; }
    set
    {
        _aBackGround= value;
        RaisePropertyChanged(() => this.aBackGround);    
    }
}

public string aPace
{
    get { return _apace; }
    set
    {
        _apace = value;
        RaisePropertyChanged(() => this.aPace);
    }
}

I can see the result of aPace correctly but a second later I get

Must create DependencySource on same Thread as the DependencyObject

exception. Can you tell me how to fix it? Thanks.

Upvotes: 1

Views: 6075

Answers (2)

Mike Fuchs
Mike Fuchs

Reputation: 12319

Whatever code is directly accessing your UI, you can only run on the UI thread. Use a dispatcher to run it there, e.g.:

Application.Current.Dispatcher.Invoke(() =>
{
    // the code that's accessing UI properties
});

Upvotes: 10

Amin Budianto
Amin Budianto

Reputation: 187

Either move your value assignment to backgroundworker completed event

or

use invoke when you assign the value in the backgroundWorker do work

this.Invoke(new Action(() => 
{
   this.aPace = "test";
}));

Upvotes: 1

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