public static void ChangeRegionSpanDependingOnPinchScale(this MKMapView mapView, MKCoordinateSpan originalSpan, nfloat scale)
{
var centerPixelX = LongitudeToPixelSpaceX(mapView.Region.Center.Longitude);
var centerPixelY = LatitudeToPixelSpaceY(mapView.Region.Center.Latitude);
var topLeftLongitude = mapView.Region.Center.Longitude - (originalSpan.LongitudeDelta / 2);
var topLeftLatitude = mapView.Region.Center.Latitude - (originalSpan.LatitudeDelta / 2);
var topLeftPixelX = LongitudeToPixelSpaceX(topLeftLongitude);
var topLeftPixelY = LatitudeToPixelSpaceY(topLeftLatitude);
var deltaPixelX = Math.Abs(centerPixelX - topLeftPixelX);
var deltaPixelY = Math.Abs(centerPixelY - topLeftPixelY);
var scaledDeltaPixelX = deltaPixelX / scale;
var scaledDeltaPixelY = deltaPixelY / scale;
var newLongitudeForTopLeft = PixelSpaceXToLongitude(centerPixelX - scaledDeltaPixelX);
var newLatitudeForTopLeft = PixelSpaceYToLatitude(centerPixelY - scaledDeltaPixelY);
var newDeltaLongitude = Math.Abs(newLongitudeForTopLeft - mapView.Region.Center.Longitude) * 2;
var newDeltaLatitude = Math.Abs(newLatitudeForTopLeft - mapView.Region.Center.Latitude) * 2;
newDeltaLatitude = Math.Max(0.0f, Math.Min(newDeltaLatitude, 90.0f));
newDeltaLongitude = Math.Max(0.0f, Math.Min(newDeltaLongitude, 90.0f));
var region = new MKCoordinateRegion(mapView.Region.Center, new MKCoordinateSpan(newDeltaLatitude, newDeltaLongitude));
mapView.SetRegion(region, false);
}
/// <summary>
/// Sets the map region to given Google Maps zoom level
/// Will convert the zoom level to the correct MKCoordinateSpan
/// Original Objective-C code found here: http://troybrant.net/blog/2010/01/set-the-zoom-level-of-an-mkmapview/
/// </summary>
public static void SetCenterCoordinate(this MKMapView mapView, CLLocationCoordinate2D centerCoordinate, float zoomLevel, bool animated)
{
// clamp large numbers to 28
zoomLevel = Math.Min(zoomLevel, 28);
// use the zoom level to compute the region
var span = CoordinateSpanWithMapView(mapView, centerCoordinate, zoomLevel);
var region = new MKCoordinateRegion(centerCoordinate, span);
// set the region like normal
mapView.SetRegion(region, animated);
}