private void UpdateRect(object sender, ElapsedEventArgs e)
{
Application.Current.Dispatcher.Invoke(
delegate {
var mousePos = FormsControl.MousePosition;
_cropRegion.X2 = mousePos.X;
_cropRegion.Y2 = mousePos.Y;
Row0.SetValue(RowDefinition.HeightProperty, new GridLength(_cropRegion.TopLeft.Y + TopLeftOffset, GridUnitType.Pixel));
Row1.SetValue(RowDefinition.HeightProperty, new GridLength(_cropRegion.BottomRight.Y - _cropRegion.TopLeft.Y, GridUnitType.Pixel));
Row2.SetValue(RowDefinition.HeightProperty, new GridLength(1, GridUnitType.Star));
Col0.SetValue(ColumnDefinition.WidthProperty, new GridLength(_cropRegion.TopLeft.X + TopLeftOffset, GridUnitType.Pixel));
Col1.SetValue(ColumnDefinition.WidthProperty, new GridLength(_cropRegion.BottomRight.X - _cropRegion.TopLeft.X, GridUnitType.Pixel));
Col2.SetValue(ColumnDefinition.WidthProperty, new GridLength(1, GridUnitType.Star));
}
);
}