How to crop image on ScheduledTaskAgent in Windows Phone

问题

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

回答1:

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();
    });
}

来源：https://stackoverflow.com/questions/13657168/how-to-crop-image-on-scheduledtaskagent-in-windows-phone