using System.Windows.Controls;

namespace Blois.Utils {

	/// <summary>
	/// Simple class to make all scrollviewers in an application scrollable.
	/// </summary>
	public static class ScrollableScrollViewer {
		private static bool initialized = false;

		public static void Initialize() {

			if (!ScrollableScrollViewer.initialized) {
				MouseWheelGenerator.MouseWheelEvent.RegisterClassHandler(typeof(ScrollViewer), ScrollableScrollViewer.HandleMouseWheel, false);

				ScrollableScrollViewer.initialized = true;
			}
		}

		private static void HandleMouseWheel(object sender, MouseWheelEventArgs e) {
			ScrollViewer sv = (ScrollViewer)sender;

			double verticalOffset = sv.VerticalOffset;
			if (e.Delta > 0 && verticalOffset > 0) {
				sv.ScrollToVerticalOffset(verticalOffset - e.Delta * 50);
				e.Handled = true;
			}
			else if (e.Delta < 0 && verticalOffset < sv.ScrollableHeight) {
				sv.ScrollToVerticalOffset(verticalOffset - e.Delta * 50);
				e.Handled = true;
			}
		}
	}
}