How to crop image on ScheduledTaskAgent in Windows Phone

Question

I need to crop an image using a ScheduledTaskAgent. Since it runs in the background I get a cross-thread exception when trying to instantiate a WriteableBitmap (as it needs to be created in the UI thread). I have a stream of the image, how would I go about cropping it without using a WriteableBitmap?

Thanks

score 4 · Accepted Answer · answered Dec 01 '12 at 10:12

4

You can use the dispatcher (and therefore the UI thread) even in a background agent:

protected override void OnInvoke(ScheduledTask task)
{
    Deployment.Current.Dispatcher.BeginInvoke(() =>
    {
        // Use the WriteableBitmap here

        this.NotifyComplete();
    });
}

answered Dec 01 '12 at 10:12

Kevin Gosse

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Thanks, after seeing this I saw the VS template even comes with Dispatcher.BeginInvoke in the constructor. – Jonas Stawski Dec 01 '12 at 13:23
What about the memory limitation of the background agent? loading an image taken by the user goes past this memory limit – Shawn Kendrot Dec 04 '12 at 01:28

How to crop image on ScheduledTaskAgent in Windows Phone

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