Is there a clean way that I can capture when a user left clicks and then drags the mouse?

I am trying to make it so that the user can scroll a richtextbox by clicking the window the richtexbox is on and dragging the mouse. Unfortunately I haven't go开发者_如何学运维tten very far:

private void Main_PreviewMouseMove(object sender, MouseEventArgs e)
{
    if (e.LeftButton == MouseButtonState.Pressed)
    {

    }
}

I've seen some suggestions on the web to track the last several x,y coordinates of the mouse and compare them to the x,y coordinates each time the mouse move event is triggered. Is there any less messy way to do this?

None that I know of. Unless you're using an API that handles it for you, you have to keep track of the information manually. And even if you did use an API just for mouse drags, it'd do the storing itself and likely just pass back the current X and Y, and the difference in X and Y, since the API wouldn't know what you want done with the information.

You'd be handling a little bit less information, but saving only about 5 lines or so of code to get the same result.