Add methods to access projection (#380)

* remove bitmap; add projection access

* Replace ScreenLocation with Point; expand iOS implementation

* fix iOS with guard let

* iOS: cast to NSObject

* fix typo

* round result of toScreenLocation()

* Revert "round result of toScreenLocation()"

This reverts commit 838726a.

* Docs: document rounding behaviour

android/src/main/java/com/mapbox/mapboxgl/MapboxMapController.java

@@ -441,6 +441,22 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
         result.success(reply);
         break;
       }
+      case "map#toScreenLocation": {
+        Map<String, Object> reply = new HashMap<>();
+        PointF pointf = mapboxMap.getProjection().toScreenLocation(new LatLng(call.argument("latitude"),call.argument("longitude")));
+        reply.put("x", pointf.x);
+        reply.put("y", pointf.y);
+        result.success(reply);
+        break;
+      }
+      case "map#toLatLng": {
+        Map<String, Object> reply = new HashMap<>();
+        LatLng latlng = mapboxMap.getProjection().fromScreenLocation(new PointF( ((Double) call.argument("x")).floatValue(), ((Double) call.argument("y")).floatValue()));
+        reply.put("latitude", latlng.getLatitude());
+        reply.put("longitude", latlng.getLongitude());
+        result.success(reply);
+        break;
+      }
       case "camera#move": {
         final CameraUpdate cameraUpdate = Convert.toCameraUpdate(call.argument("cameraUpdate"), mapboxMap, density);
         if (cameraUpdate != null) {

example/lib/map_ui.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:math';
+
 import 'package:flutter/material.dart';
 import 'package:mapbox_gl/mapbox_gl.dart';
 
@@ -266,6 +268,10 @@ class MapUiBodyState extends State<MapUiBody> {
       },
       onMapLongClick: (point, latLng) async {
         print("Map long press: ${point.x},${point.y}   ${latLng.latitude}/${latLng.longitude}");
+        Point convertedPoint = await mapController.toScreenLocation(latLng);
+        LatLng convertedLatLng = await mapController.toLatLng(point);
+        print("Map long press converted: ${convertedPoint.x},${convertedPoint.y}   ${convertedLatLng.latitude}/${convertedLatLng.longitude}");
+
         List features = await mapController.queryRenderedFeatures(point, [], null);
         if (features.length>0) {
           print(features[0]);

ios/Classes/MapboxMapController.swift

@@ -165,6 +165,26 @@ class MapboxMapController: NSObject, FlutterPlatformView, MGLMapViewDelegate, Ma
             reply["sw"] = [visibleRegion.sw.latitude, visibleRegion.sw.longitude] as NSObject
             reply["ne"] = [visibleRegion.ne.latitude, visibleRegion.ne.longitude] as NSObject
             result(reply)
+        case "map#toScreenLocation":
+            guard let arguments = methodCall.arguments as? [String: Any] else { return }
+            guard let latitude = arguments["latitude"] as? Double else { return }
+            guard let longitude = arguments["longitude"] as? Double else { return }
+            let latlng = CLLocationCoordinate2DMake(latitude, longitude)
+            let returnVal = mapView.convert(latlng, toPointTo: mapView)
+            var reply = [String: NSObject]()
+            reply["x"] = returnVal.x as NSObject
+            reply["y"] = returnVal.y as NSObject
+            result(reply)
+        case "map#toLatLng":
+            guard let arguments = methodCall.arguments as? [String: Any] else { return }
+            guard let x = arguments["x"] as? Double else { return }
+            guard let y = arguments["y"] as? Double else { return }
+            let screenPoint: CGPoint = CGPoint(x: y, y:y)
+            let coordinates: CLLocationCoordinate2D = mapView.convert(screenPoint, toCoordinateFrom: mapView)
+            var reply = [String: NSObject]()
+            reply["latitude"] = coordinates.latitude as NSObject
+            reply["longitude"] = coordinates.longitude as NSObject
+            result(reply)
         case "camera#move":
             guard let arguments = methodCall.arguments as? [String: Any] else { return }
             guard let cameraUpdate = arguments["cameraUpdate"] as? [Any] else { return }

lib/mapbox_gl.dart

@@ -34,7 +34,7 @@ export 'package:mapbox_gl_platform_interface/mapbox_gl_platform_interface.dart'
         Line,
         LineOptions;
 
-part 'src/bitmap.dart';
+
 part 'src/controller.dart';
 part 'src/mapbox_map.dart';
 part 'src/global.dart';

lib/src/controller.dart

@@ -670,4 +670,21 @@ class MapboxMapController extends ChangeNotifier {
     await MapboxGlPlatform.getInstance(_id)
         .setSymbolTextIgnorePlacement(enable);
   }
+
+  /// Returns the point on the screen that corresponds to a geographical coordinate ([latLng]). The screen location is in screen pixels (not display pixels) relative to the top left of the map (not of the whole screen)
+  /// 
+  /// Note: The resulting x and y coordinates are rounded to [int] on web, on other platforms they may differ very slightly (in the range of about 10^-10) from the actual nearest screen coordinate.
+  /// You therefore might want to round them appropriately, depending on your use case.
+  /// 
+  /// Returns null if [latLng] is not currently visible on the map.
+  Future<Point> toScreenLocation(LatLng latLng) async{
+    return MapboxGlPlatform.getInstance(_id).toScreenLocation(latLng);
+  }
+
+  /// Returns the geographic location (as [LatLng]) that corresponds to a point on the screen. The screen location is specified in screen pixels (not display pixels) relative to the top left of the map (not the top left of the whole screen).
+  Future<LatLng> toLatLng(Point screenLocation) async{
+    return MapboxGlPlatform.getInstance(_id).toLatLng(screenLocation);
+  }
+
+
 }

mapbox_gl_platform_interface/lib/src/location.dart

@@ -103,3 +103,4 @@ class LatLngBounds {
   @override
   int get hashCode => hashValues(southwest, northeast);
 }
+

mapbox_gl_platform_interface/lib/src/mapbox_gl_platform_interface.dart

@@ -210,4 +210,14 @@ abstract class MapboxGlPlatform {
     throw UnimplementedError(
         'setSymbolTextIgnorePlacement() has not been implemented.');
   }
+
+  Future<Point> toScreenLocation(LatLng latLng) async{
+    throw UnimplementedError(
+        'toScreenLocation() has not been implemented.');
+  }
+
+  Future<LatLng> toLatLng(Point screenLocation) async{
+      throw UnimplementedError(
+        'toLatLng() has not been implemented.');
+  }
 }

mapbox_gl_platform_interface/lib/src/method_channel_mapbox_gl.dart

@@ -182,23 +182,22 @@ class MethodChannelMapboxGl extends MapboxGlPlatform {
   }
 
   @override
-  Future<List<Symbol>> addSymbols(List<SymbolOptions> options, [List<Map> data]) async {
+  Future<List<Symbol>> addSymbols(List<SymbolOptions> options,
+      [List<Map> data]) async {
     final List<dynamic> symbolIds = await _channel.invokeMethod(
       'symbols#addAll',
       <String, dynamic>{
         'options': options.map((o) => o.toJson()).toList(),
       },
     );
-    final List<Symbol> symbols = symbolIds.asMap().map(
-            (i, id) => MapEntry(
+    final List<Symbol> symbols = symbolIds
+        .asMap()
+        .map((i, id) => MapEntry(
             i,
-            Symbol(
-                id,
-                options.elementAt(i),
-                data != null && data.length > i ? data.elementAt(i) : null
-            )
-        )
-    ).values.toList();
+            Symbol(id, options.elementAt(i),
+                data != null && data.length > i ? data.elementAt(i) : null)))
+        .values
+        .toList();
 
     return symbols;
   }
@@ -212,7 +211,7 @@ class MethodChannelMapboxGl extends MapboxGlPlatform {
   }
 
   @override
-  Future<LatLng> getSymbolLatLng(Symbol symbol) async{
+  Future<LatLng> getSymbolLatLng(Symbol symbol) async {
     Map mapLatLng =
         await _channel.invokeMethod('symbol#getGeometry', <String, dynamic>{
       'symbol': symbol._id,
@@ -249,7 +248,7 @@ class MethodChannelMapboxGl extends MapboxGlPlatform {
   }
 
   @override
-  Future<List<LatLng>> getLineLatLngs(Line line) async{
+  Future<List<LatLng>> getLineLatLngs(Line line) async {
     List latLngList =
         await _channel.invokeMethod('line#getGeometry', <String, dynamic>{
       'line': line._id,
@@ -453,4 +452,32 @@ class MethodChannelMapboxGl extends MapboxGlPlatform {
       return new Future.error(e);
     }
   }
+
+  @override
+  Future<Point> toScreenLocation(LatLng latLng) async {
+    try {
+      var screenPosMap = await _channel
+          .invokeMethod('map#toScreenLocation', <String, dynamic>{
+        'latitude': latLng.latitude,
+        'longitude':latLng.longitude,
+      });
+      return Point(screenPosMap['x'], screenPosMap['y']);
+    } on PlatformException catch (e) {
+      return new Future.error(e);
+    }
+  }
+
+  @override
+  Future<LatLng> toLatLng(Point screenLocation) async {
+    try {
+      var latLngMap = await _channel
+          .invokeMethod('map#toLatLng', <String, dynamic>{
+        'x': screenLocation.x,
+        'y':screenLocation.y,
+      });
+      return LatLng(latLngMap['latitude'], latLngMap['longitude']);
+    } on PlatformException catch (e) {
+      return new Future.error(e);
+    }
+  }
 }

mapbox_gl_web/lib/src/mapbox_map_controller.dart

@@ -615,4 +615,16 @@ class MapboxMapController extends MapboxGlPlatform
       _map.keyboard.disable();
     }
   }
+
+  @override
+  Future<Point> toScreenLocation(LatLng latLng) async {
+    var screenPosition = _map.project(LngLat(latLng.longitude, latLng.latitude));
+    return Point(screenPosition.x.round(), screenPosition.y.round());
+  }
+
+  @override
+  Future<LatLng> toLatLng(Point screenLocation) async {
+    var lngLat = _map.unproject(mapbox.Point(screenLocation.x, screenLocation.y));
+    return LatLng(lngLat.lat, lngLat.lng);
+  }
 }