How to take a screenshot of a WPF control?

A screenshot is a shot of the screen... everything on the screen. What you want is to save an image from a single UIElement and you can do that using the RenderTargetBitmap.Render Method. This method takes a Visual input parameter and luckily, that is one of the base classes for all UIElements. So assuming that you want to save a .png file, you could do this:

RenderTargetBitmap renderTargetBitmap = 
    new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Pbgra32);
renderTargetBitmap.Render(yourMapControl); 
PngBitmapEncoder pngImage = new PngBitmapEncoder();
pngImage.Frames.Add(BitmapFrame.Create(renderTargetBitmap));
using (Stream fileStream = File.Create(filePath))
{
    pngImage.Save(fileStream);
}