When I reply you last time, the post hadn't shows it's an Android question, so I reply you the code is our other product.
Because I hadn't the environment today for Android, so maybe I will test that this Friday.
And if you want to find the correct value to set mapView.CurrentExtent, I think the code as below should be helpful.
double scale = mapView.CurrentScale;
PointShape point = new PointShape(0, 0); // Put your point here
RectangleShape rect = new RectangleShape(point.X - 0.5, point.Y + 0.5, point.X + 0.5, point.Y - 0.5);
// Please modify the parameter to make it works
RectangleShape resultRectangle = ExtentHelper.ZoomToScale(scale, rect, mapView.MapUnit, mapView.Width, mapView.Height);
mapView.CurrentExtent = resultRectangle;