static_map_provider.dart

import 'dart:async';

import 'package:map_view/location.dart';
import 'package:map_view/polyline.dart';
import 'package:uri/uri.dart';

import 'locations.dart';
import 'map_view.dart';
import 'map_view_type.dart';

class StaticMapProvider {
  final String googleMapsApiKey;
  static const int defaultZoomLevel = 4;
  static const int defaultWidth = 600;
  static const int defaultHeight = 400;
  static const StaticMapViewType defaultMaptype = StaticMapViewType.roadmap;

  StaticMapProvider(this.googleMapsApiKey);

  ///
  /// Creates a Uri for the Google Static Maps API
  /// Centers the map on [center] using a zoom of [zoomLevel]
  /// Specify a [width] and [height] that you would like the resulting image to be. The default is 600w x 400h
  ///

  Uri getStaticUri(Location center, int zoomLevel,
      {int width, int height, StaticMapViewType mapType}) {
    return _buildUrl(null, null, center, zoomLevel ?? defaultZoomLevel, width ?? defaultWidth,
        height ?? defaultHeight, mapType ?? defaultMaptype);
  }

  ///
  /// Creates a Uri for the Google Static Maps API using a list of locations to create pins on the map
  /// [locations] must have at least 1 location
  /// Specify a [width] and [height] that you would like the resulting image to be. The default is 600w x 400h
  ///

  Uri getStaticUriWithMarkers(List<Marker> markers,
      {int width, int height, StaticMapViewType maptype, Location center}) {
    return _buildUrl(markers, null, center, null, width ?? defaultWidth, height ?? defaultHeight,
        maptype ?? defaultMaptype);
  }

  ///
  /// Creates a Uri for the Google Static Maps API using a list of polyline to create single or multiple polylines on the map.
  /// [polylines] must have at least 1 polyline
  /// Specify a [width] and [height] that you would like the resulting image to be. The default is 600w x 400h
  ///

  Uri getStaticUriWithPolyline(List<Polyline> polylines,
      {int width, int height, StaticMapViewType maptype, Location center}) {
    return _buildUrl(null, polylines, center, null, width ?? defaultWidth, height ?? defaultHeight,
        maptype ?? defaultMaptype);
  }

  ///
  /// Creates a Uri for the Google Static Maps API using a list of locations to create pins on the map
  /// [locations] must have at least 1 location
  /// Specify a [width] and [height] that you would like the resulting image to be. The default is 600w x 400h
  /// Centers the map on [center] using a zoom of [zoomLevel]
  ///
  Uri getStaticUriWithMarkersAndZoom(List<Marker> markers,
      {int width, int height, StaticMapViewType maptype, Location center, int zoomLevel}) {
    return _buildUrl(markers, null, center, zoomLevel, width ?? defaultWidth,
        height ?? defaultHeight, maptype ?? defaultMaptype);
  }

  ///
  /// Creates a Uri for the Google Static Maps API using an active MapView
  /// This method is useful for generating a static image
  /// [mapView] must currently be visible when you call this.
  /// Specify a [width] and [height] that you would like the resulting image to be. The default is 600w x 400h
  ///
  Future<Uri> getImageUriFromMap(MapView mapView,
      {int width, int height, StaticMapViewType maptype}) async {
    var markers = await mapView.visibleAnnotations;
    var center = await mapView.centerLocation;
    var zoom = await mapView.zoomLevel;
    return _buildUrl(markers, null, center, zoom.toInt(), width ?? defaultWidth,
        height ?? defaultHeight, maptype ?? defaultMaptype);
  }

  Uri _buildUrl(List<Marker> locations, List<Polyline> polylines, Location center, int zoomLevel,
      int width, int height, StaticMapViewType mapType) {
    var finalUri = new UriBuilder()
      ..scheme = 'https'
      ..host = 'maps.googleapis.com'
      ..port = 443
      ..path = '/maps/api/staticmap';
    String polylineUrlParam = "";
    var locationsProvided = locations != null && locations.length > 0;
    var polylinesProvided = polylines != null && polylines.length > 0;

    if (center == null && !locationsProvided && !polylinesProvided) {
      center = Locations.centerOfUSA;
    }
    if (locationsProvided) {
      List<String> markers = new List();
      locations.forEach((location) {
        num lat = location.latitude;
        num lng = location.longitude;
        String marker = '$lat,$lng';
        markers.add(marker);
      });
      String markersString = markers.join('|');
      finalUri.queryParameters = {
        'markers': markersString,
        'size': '${width ?? defaultWidth}x${height ?? defaultHeight}',
        'maptype': _getMapTypeQueryParam(mapType),
        'key': googleMapsApiKey,
      };
    } else if (polylinesProvided) {
      StringBuffer polylineBuffer = new StringBuffer();
      StringBuffer polylineUrlComponent = new StringBuffer();
      for (Polyline polyline in polylines) {
        polylineBuffer.write('&path=');
        if (polyline.color != null) {
          polylineUrlComponent
              .write('color:0x${polyline.color.value.toRadixString(16).substring(2)}|');
        }
        polylineUrlComponent.write(polyline.points
            .map((Location location) =>
                location.latitude.toString() + ',' + location.longitude.toString())
            .join("|"));
        polylineBuffer.write(Uri.decodeComponent(polylineUrlComponent.toString()));
        polylineUrlComponent.clear();
      }
      polylineUrlParam = polylineBuffer.toString();
      finalUri.queryParameters = {
        'size': '${width ?? defaultWidth}x${height ?? defaultHeight}',
        'maptype': _getMapTypeQueryParam(mapType),
        'key': googleMapsApiKey,
      };
      polylineUrlParam = polylineBuffer.toString();
    } else {
      if (center == null) center = Locations.centerOfUSA;
      finalUri.queryParameters = {
        'center': '${center.latitude},${center.longitude}',
        'zoom': zoomLevel.toString(),
        'size': '${width ?? defaultWidth}x${height ?? defaultHeight}',
        'maptype': _getMapTypeQueryParam(mapType),
        'key': googleMapsApiKey,
      };
    }

    if (center != null)
      finalUri.queryParameters['center'] = '${center.latitude},${center.longitude}';

    var uri = finalUri.build();
    if (polylinesProvided) {
      //hack for polylines to support different colors for each polyline
      //using Map<String, String> you can't pass params with the same - but google supports it
      uri = Uri.parse(uri.toString() + polylineUrlParam);
    }
    print(uri);
    return uri;
  }

  String _getMapTypeQueryParam(StaticMapViewType maptype) {
    String mapTypeQueryParam;
    switch (maptype) {
      case StaticMapViewType.roadmap:
        mapTypeQueryParam = "roadmap";
        break;
      case StaticMapViewType.satellite:
        mapTypeQueryParam = "satellite";
        break;
      case StaticMapViewType.hybrid:
        mapTypeQueryParam = "hybrid";
        break;
      case StaticMapViewType.terrain:
        mapTypeQueryParam = "terrain";
        break;
    }
    return mapTypeQueryParam;
  }
}