Add animate to bounds on Map from LatLngBounds (#22)

* add setBounds based on setVisibleMapRect from Map

* add newLatLngBounds to create CameraUpdate

* add parsed from Swift

* add function to example

* add convert coordinate to point

* add example

* remove printing

Author: nghiashiyi

example/lib/animate_camera.dart

@@ -89,6 +89,19 @@ class AnimateCameraState extends State<AnimateCamera> {
                   },
                   child: const Text('newLatLngZoom'),
                 ),
+                FlatButton(
+                  onPressed: () {
+                    mapController.animateCamera(
+                      CameraUpdate.newLatLngBounds(
+                        LatLngBounds(
+                            southwest: LatLng(37.749146, -122.71829295684518),
+                            northeast: LatLng(37.94134713198227, -122.498971)
+                        ),
+                        11.0,
+                      ),
+                    );
+                  },
+                  child: const Text('newLatLngBounds'))
               ],
             ),
             Column(

example/lib/move_camera.dart

@@ -88,6 +88,20 @@ class MoveCameraState extends State<MoveCamera> {
                   },
                   child: const Text('newLatLngZoom'),
                 ),
+                FlatButton(
+                  onPressed: () {
+                    mapController.moveCamera(
+                      CameraUpdate.newLatLngBounds(
+                        LatLngBounds(
+                          southwest: LatLng(37.749146, -122.71829295684518),
+                          northeast: LatLng(37.94134713198227, -122.498971)
+                        ),
+                        11.0,
+                      ),
+                    );
+                  },
+                  child: const Text('newLatLngBounds'),
+                ),
               ],
             ),
             Column(

example/lib/place_annotation.dart

@@ -254,6 +254,18 @@ class PlaceAnnotationBodyState extends State<PlaceAnnotationBody> {
                           child: const Text('add defaultAnnotation'),
                           onPressed: () => _add('pin'),
                         ),
+                        FlatButton(
+                          child: const Text('Get Visible Region Bounds'),
+                          onPressed: () async {
+                            final point = await controller.getScreenCoordinate(LatLng(
+                                center.latitude +
+                                    sin(_annotationIdCounter * pi / 6.0) / 20.0,
+                                center.longitude +
+                                    cos(_annotationIdCounter * pi / 6.0) /
+                                        20.0));
+                            print("Point $point");
+                          },
+                        ),
                         FlatButton(
                           child: const Text('add markerAnnotation'),
                           onPressed: () => _add('marker'),

ios/Classes/MapView/AppleMapController.swift

@@ -199,15 +199,30 @@ public class AppleMapController : NSObject, FlutterPlatformView, MKMapViewDelega
                 case "camera#animate":
                     let positionData :Dictionary<String, Any> = self.toPositionData(data: args["cameraUpdate"] as! Array<Any>, animated: true)
                     if !positionData.isEmpty {
-                        self.mapView.setCenterCoordinate(positionData, animated: true)
+                        guard let _ = positionData["moveToBounds"] else {
+                            self.mapView.setCenterCoordinate(positionData, animated: true)
+                            return
+                        }
+                        self.mapView.setBounds(positionData, animated: true)
                     }
                     result(nil)
                 case "camera#move":
                     let positionData :Dictionary<String, Any> = self.toPositionData(data: args["cameraUpdate"] as! Array<Any>, animated: false)
                     if !positionData.isEmpty {
-                        self.mapView.setCenterCoordinate(positionData, animated: false)
+                        guard let _ = positionData["moveToBounds"] else {
+                            self.mapView.setCenterCoordinate(positionData, animated: false)
+                            return
+                        }
+                        self.mapView.setBounds(positionData, animated: false)
                     }
                     result(nil)
+                case "camera#convert":
+                    guard let annotation = args["annotation"] as? Array<Double> else {
+                        result(nil)
+                        return
+                    }
+                    let point = self.mapView.convert(CLLocationCoordinate2D(latitude: annotation[0] , longitude: annotation[1]), toPointTo: self.view())
+                    result(["point": [point.x, point.y]])
                 default:
                     result(FlutterMethodNotImplemented)
                     return
@@ -261,6 +276,11 @@ public class AppleMapController : NSObject, FlutterPlatformView, MKMapViewDelega
                     let zoom: Double = data[2] as? Double ?? 0
                     positionData = ["target": _positionData, "zoom": zoom]
                 }
+            case "newLatLngBounds":
+                if let _positionData: Array<Any> = data[1] as? Array<Any> {
+                    let padding: Double = data[2] as? Double ?? 0
+                    positionData = ["target": _positionData, "padding": padding, "moveToBounds": true]
+                }
             case "zoomBy":
                 if let zoomBy: Double = data[1] as? Double {
                     mapView.zoomBy(zoomBy: zoomBy, animated: animated)

ios/Classes/MapView/MapViewExtension.swift

@@ -136,6 +136,16 @@ public extension MKMapView {
         }
     }
 
+    func setBounds(_ positionData: Dictionary<String, Any>, animated: Bool) {
+        guard let targetList :Array<Array<CLLocationDegrees>> = positionData["target"] as? Array<Array<CLLocationDegrees>> else { return }
+        let padding :Double = positionData["padding"] as? Double ?? 0
+        let coodinates: Array<CLLocationCoordinate2D> = targetList.map { (coordinate : Array<CLLocationDegrees>) in
+            return CLLocationCoordinate2D(latitude:  coordinate[0], longitude: coordinate[1])
+        }
+        guard let mapRect = coodinates.mapRect() else { return }
+        self.setVisibleMapRect(mapRect, edgePadding: UIEdgeInsets(top: CGFloat(padding), left: CGFloat(padding), bottom: CGFloat(padding), right: CGFloat(padding)), animated: animated)
+    }
+    
     func setCenterCoordinateRegion(centerCoordinate: CLLocationCoordinate2D, zoomLevel: Double, animated: Bool) {
         // clamp large numbers to 28
         let zoomL = min(zoomLevel, 28);
@@ -315,3 +325,34 @@ public extension MKMapView {
         Holder._heading = newHeading
     }
 }
+
+extension Array where Element == CLLocationCoordinate2D {
+    func mapRect() -> MKMapRect? {
+        return map(MKMapPoint.init).mapRect()
+    }
+}
+
+extension Array where Element == CLLocation {
+    func mapRect() -> MKMapRect? {
+        return map { MKMapPoint($0.coordinate) }.mapRect()
+    }
+}
+
+extension Array where Element == MKMapPoint {
+    func mapRect() -> MKMapRect? {
+        guard count > 0 else { return nil }
+
+        let xs = map { $0.x }
+        let ys = map { $0.y }
+
+        let west = xs.min()!
+        let east = xs.max()!
+        let width = east - west
+
+        let south = ys.min()!
+        let north = ys.max()!
+        let height = north - south
+
+        return MKMapRect(x: west, y: south, width: width, height: height)
+    }
+}

lib/src/camera.dart

@@ -109,6 +109,18 @@ class CameraUpdate {
     );
   }
 
+  /// Returns a camera update that transforms the camera so that the specified
+  /// geographical bounding box is centered in the map view at the greatest
+  /// possible zoom level. A non-zero [padding] insets the bounding box from the
+  /// map view's edges. The camera's new tilt and bearing will both be 0.0.
+  static CameraUpdate newLatLngBounds(LatLngBounds bounds, double padding) {
+    return CameraUpdate._(<dynamic>[
+      'newLatLngBounds',
+      bounds._toJson(),
+      padding,
+    ]);
+  }
+
   /// Returns a camera update that modifies the camera zoom level by the
   /// specified amount. The optional [focus] is a screen point whose underlying
   /// geographical location should be invariant, if possible, by the movement.

lib/src/controller.dart

@@ -233,4 +233,21 @@ class AppleMapController {
 
     return LatLngBounds(northeast: northeast, southwest: southwest);
   }
+
+
+  /// A projection is used to translate between on screen location and geographic coordinates.
+  /// Screen location is in screen pixels (not display pixels) with respect to the top left corner
+  /// of the map, not necessarily of the whole screen.
+  Future<Offset> getScreenCoordinate(LatLng latLng) async {
+    final point = await channel
+        .invokeMapMethod<String, dynamic>(
+        'camera#convert', <String, dynamic>{
+      'annotation': [latLng.latitude, latLng.longitude]
+    });
+    if (!point.containsKey('point')) {
+      return null;
+    }
+    final doubles = List<double>.from(point['point']);
+    return Offset(doubles.first, doubles.last);
+  }
 }

lib/src/location.dart

@@ -114,6 +114,11 @@ class LatLngBounds {
         o.northeast == northeast;
   }
 
+  /// Converts this object to something serializable in JSON.
+  dynamic _toJson() {
+    return <dynamic>[southwest._toJson(), northeast._toJson()];
+  }
+
   @override
   int get hashCode => hashValues(southwest, northeast);
 }