Add minZoom and maxZoom properties for android and ios (react-native-maps#1360)

* Add minZoom and maxZoom properties for android and ios

* Add min/max zoom level properties to AIRMap.h

* Fix assignation for zoom levels for gmaps ios

* Resolve conflicts, fix potential nil value on ios

* Resolve conflicts

Author: foyarash

lib/android/src/main/java/com/airbnb/android/react/maps/AirMapManager.java

@@ -178,6 +178,16 @@ public void setPitchEnabled(AirMapView view, boolean pitchEnabled) {
     view.map.getUiSettings().setTiltGesturesEnabled(pitchEnabled);
   }
 
+  @ReactProp(name = "minZoomLevel")
+  public void setMinZoomLevel(AirMapView view, float minZoomLevel) {
+    view.map.setMinZoomPreference(minZoomLevel);
+  }
+
+  @ReactProp(name = "maxZoomLevel")
+  public void setMaxZoomLevel(AirMapView view, float maxZoomLevel) {
+    view.map.setMaxZoomPreference(maxZoomLevel);
+  }
+
   @Override
   public void receiveCommand(AirMapView view, int commandId, @Nullable ReadableArray args) {
     Integer duration;

lib/components/MapView.js

@@ -385,6 +385,16 @@ const propTypes = {
    */
   onMarkerDragEnd: PropTypes.func,
 
+  /**
+   * Minimum zoom value for the map, must be between 0 and 20
+   */
+  minZoomLevel: PropTypes.number,
+
+  /**
+   * Maximum zoom value for the map, must be between 0 and 20
+   */
+  maxZoomLevel: PropTypes.number,
+
 };
 
 class MapView extends React.Component {

lib/ios/AirGoogleMaps/AIRGoogleMap.m

@@ -300,6 +300,13 @@ - (BOOL)showsMyLocationButton {
   return self.settings.myLocationButton;
 }
 
+- (void)setMinZoomLevel:(CGFloat)minZoomLevel {
+  [self setMinZoom:minZoomLevel maxZoom:self.maxZoom ];
+}
+
+- (void)setMaxZoomLevel:(CGFloat)maxZoomLevel {
+  [self setMinZoom:self.minZoom maxZoom:maxZoomLevel ];
+}
 
 + (MKCoordinateRegion) makeGMSCameraPositionFromMap:(GMSMapView *)map andGMSCameraPosition:(GMSCameraPosition *)position {
   // solution from here: http://stackoverflow.com/a/16587735/1102215

lib/ios/AirGoogleMaps/AIRGoogleMapManager.m

@@ -66,6 +66,8 @@ - (UIView *)view
 RCT_EXPORT_VIEW_PROPERTY(onRegionChange, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(onRegionChangeComplete, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(mapType, GMSMapViewType)
+RCT_EXPORT_VIEW_PROPERTY(minZoomLevel, CGFloat)
+RCT_EXPORT_VIEW_PROPERTY(maxZoomLevel, CGFloat)
 
 RCT_EXPORT_METHOD(animateToRegion:(nonnull NSNumber *)reactTag
                   withRegion:(MKCoordinateRegion)region

lib/ios/AirMaps/AIRMap.h

@@ -37,6 +37,8 @@ extern const CGFloat AIRMapZoomBoundBuffer;
 @property (nonatomic, assign) UIEdgeInsets legalLabelInsets;
 @property (nonatomic, strong) NSTimer *regionChangeObserveTimer;
 @property (nonatomic, assign) MKCoordinateRegion initialRegion;
+@property (nonatomic, assign) CGFloat minZoomLevel;
+@property (nonatomic, assign) CGFloat maxZoomLevel;
 
 @property (nonatomic, assign) CLLocationCoordinate2D pendingCenter;
 @property (nonatomic, assign) MKCoordinateSpan pendingSpan;

lib/ios/AirMaps/AIRMapManager.h

@@ -8,7 +8,23 @@
  */
 
 #import <React/RCTViewManager.h>
+#import "AIRMap.h"
+
+#define MERCATOR_RADIUS 85445659.44705395
+#define MERCATOR_OFFSET 268435456
+#define MAX_GOOGLE_LEVELS 20
 
 @interface AIRMapManager : RCTViewManager
 
+
+- (void)setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate
+    zoomLevel:(double)zoomLevel
+    animated:(BOOL)animated
+    mapView:(AIRMap *)mapView;
+
+- (MKCoordinateRegion)coordinateRegionWithMapView:(AIRMap *)mapView
+                                 centerCoordinate:(CLLocationCoordinate2D)centerCoordinate
+								                     andZoomLevel:(double)zoomLevel;
+- (double) zoomLevel:(AIRMap *)mapView;
+
 @end

lib/ios/AirMaps/AIRMapManager.m

@@ -97,6 +97,9 @@ - (UIView *)view
 RCT_EXPORT_VIEW_PROPERTY(onMarkerDragEnd, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(onCalloutPress, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(initialRegion, MKCoordinateRegion)
+RCT_EXPORT_VIEW_PROPERTY(minZoomLevel, CGFloat)
+RCT_EXPORT_VIEW_PROPERTY(maxZoomLevel, CGFloat)
+
 
 RCT_CUSTOM_VIEW_PROPERTY(region, MKCoordinateRegion, AIRMap)
 {
@@ -625,11 +628,19 @@ - (void)mapView:(AIRMap *)mapView regionWillChangeAnimated:(__unused BOOL)animat
 
 - (void)mapView:(AIRMap *)mapView regionDidChangeAnimated:(__unused BOOL)animated
 {
+    CGFloat zoomLevel = [self zoomLevel:mapView];
     [mapView.regionChangeObserveTimer invalidate];
     mapView.regionChangeObserveTimer = nil;
 
     [self _regionChanged:mapView];
 
+    if (mapView.minZoomLevel != nil && zoomLevel < mapView.minZoomLevel) {
+      [self setCenterCoordinate:[mapView centerCoordinate] zoomLevel:mapView.minZoomLevel animated:TRUE mapView:mapView];
+    }
+    else if (mapView.maxZoomLevel != nil && zoomLevel > mapView.maxZoomLevel) {
+      [self setCenterCoordinate:[mapView centerCoordinate] zoomLevel:mapView.maxZoomLevel animated:TRUE mapView:mapView];
+    }
+
     // Don't send region did change events until map has
     // started rendering, as these won't represent the final location
     if (mapView.hasStartedRendering) {
@@ -665,6 +676,7 @@ - (void)_regionChanged:(AIRMap *)mapView
     BOOL needZoom = NO;
     CGFloat newLongitudeDelta = 0.0f;
     MKCoordinateRegion region = mapView.region;
+    CGFloat zoomLevel = [self zoomLevel:mapView];
     // On iOS 7, it's possible that we observe invalid locations during initialization of the map.
     // Filter those out.
     if (!CLLocationCoordinate2DIsValid(region.center)) {
@@ -759,4 +771,161 @@ - (double)metersFromPixel:(NSUInteger)px atPoint:(CGPoint)pt forMap:(AIRMap *)ma
     return MKMetersBetweenMapPoints(MKMapPointForCoordinate(coordA), MKMapPointForCoordinate(coordB));
 }
 
++ (double)longitudeToPixelSpaceX:(double)longitude
+{
+    return round(MERCATOR_OFFSET + MERCATOR_RADIUS * longitude * M_PI / 180.0);
+}
+
++ (double)latitudeToPixelSpaceY:(double)latitude
+{
+	if (latitude == 90.0) {
+		return 0;
+	} else if (latitude == -90.0) {
+		return MERCATOR_OFFSET * 2;
+	} else {
+		return round(MERCATOR_OFFSET - MERCATOR_RADIUS * logf((1 + sinf(latitude * M_PI / 180.0)) / (1 - sinf(latitude * M_PI / 180.0))) / 2.0);
+	}
+}
+
++ (double)pixelSpaceXToLongitude:(double)pixelX
+{
+    return ((round(pixelX) - MERCATOR_OFFSET) / MERCATOR_RADIUS) * 180.0 / M_PI;
+}
+
++ (double)pixelSpaceYToLatitude:(double)pixelY
+{
+    return (M_PI / 2.0 - 2.0 * atan(exp((round(pixelY) - MERCATOR_OFFSET) / MERCATOR_RADIUS))) * 180.0 / M_PI;
+}
+
+#pragma mark -
+#pragma mark Helper methods
+
+- (MKCoordinateSpan)coordinateSpanWithMapView:(AIRMap *)mapView
+                             centerCoordinate:(CLLocationCoordinate2D)centerCoordinate
+                                 andZoomLevel:(double)zoomLevel
+{
+    // convert center coordiate to pixel space
+    double centerPixelX = [AIRMapManager longitudeToPixelSpaceX:centerCoordinate.longitude];
+    double centerPixelY = [AIRMapManager latitudeToPixelSpaceY:centerCoordinate.latitude];
+
+    // determine the scale value from the zoom level
+    double zoomExponent = 20 - zoomLevel;
+    double zoomScale = pow(2, zoomExponent);
+
+    // scale the map’s size in pixel space
+    CGSize mapSizeInPixels = mapView.bounds.size;
+    double scaledMapWidth = mapSizeInPixels.width * zoomScale;
+    double scaledMapHeight = mapSizeInPixels.height * zoomScale;
+
+    // figure out the position of the top-left pixel
+    double topLeftPixelX = centerPixelX - (scaledMapWidth / 2);
+    double topLeftPixelY = centerPixelY - (scaledMapHeight / 2);
+
+    // find delta between left and right longitudes
+    CLLocationDegrees minLng = [AIRMapManager pixelSpaceXToLongitude:topLeftPixelX];
+    CLLocationDegrees maxLng = [AIRMapManager pixelSpaceXToLongitude:topLeftPixelX + scaledMapWidth];
+    CLLocationDegrees longitudeDelta = maxLng - minLng;
+
+    // find delta between top and bottom latitudes
+    CLLocationDegrees minLat = [AIRMapManager pixelSpaceYToLatitude:topLeftPixelY];
+    CLLocationDegrees maxLat = [AIRMapManager pixelSpaceYToLatitude:topLeftPixelY + scaledMapHeight];
+    CLLocationDegrees latitudeDelta = -1 * (maxLat - minLat);
+
+    // create and return the lat/lng span
+    MKCoordinateSpan span = MKCoordinateSpanMake(latitudeDelta, longitudeDelta);
+    return span;
+}
+
+#pragma mark -
+#pragma mark Public methods
+
+- (void)setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate
+                  zoomLevel:(double)zoomLevel
+                   animated:(BOOL)animated
+                    mapView:(AIRMap *)mapView
+{
+    // clamp large numbers to 28
+    zoomLevel = MIN(zoomLevel, 28);
+
+    // use the zoom level to compute the region
+    MKCoordinateSpan span = [self coordinateSpanWithMapView:mapView centerCoordinate:centerCoordinate andZoomLevel:zoomLevel];
+    MKCoordinateRegion region = MKCoordinateRegionMake(centerCoordinate, span);
+
+    // set the region like normal
+    [mapView setRegion:region animated:animated];
+}
+
+//KMapView cannot display tiles that cross the pole (as these would involve wrapping the map from top to bottom, something that a Mercator projection just cannot do).
+-(MKCoordinateRegion)coordinateRegionWithMapView:(AIRMap *)mapView
+                                centerCoordinate:(CLLocationCoordinate2D)centerCoordinate
+                                    andZoomLevel:(double)zoomLevel
+{
+	// clamp lat/long values to appropriate ranges
+	centerCoordinate.latitude = MIN(MAX(-90.0, centerCoordinate.latitude), 90.0);
+	centerCoordinate.longitude = fmod(centerCoordinate.longitude, 180.0);
+
+	// convert center coordiate to pixel space
+	double centerPixelX = [AIRMapManager longitudeToPixelSpaceX:centerCoordinate.longitude];
+	double centerPixelY = [AIRMapManager latitudeToPixelSpaceY:centerCoordinate.latitude];
+
+	// determine the scale value from the zoom level
+	double zoomExponent = 20 - zoomLevel;
+	double zoomScale = pow(2, zoomExponent);
+
+	// scale the map’s size in pixel space
+	CGSize mapSizeInPixels = mapView.bounds.size;
+	double scaledMapWidth = mapSizeInPixels.width * zoomScale;
+	double scaledMapHeight = mapSizeInPixels.height * zoomScale;
+
+	// figure out the position of the left pixel
+	double topLeftPixelX = centerPixelX - (scaledMapWidth / 2);
+
+	// find delta between left and right longitudes
+	CLLocationDegrees minLng = [AIRMapManager pixelSpaceXToLongitude:topLeftPixelX];
+	CLLocationDegrees maxLng = [AIRMapManager pixelSpaceXToLongitude:topLeftPixelX + scaledMapWidth];
+	CLLocationDegrees longitudeDelta = maxLng - minLng;
+
+	// if we’re at a pole then calculate the distance from the pole towards the equator
+	// as MKMapView doesn’t like drawing boxes over the poles
+	double topPixelY = centerPixelY - (scaledMapHeight / 2);
+	double bottomPixelY = centerPixelY + (scaledMapHeight / 2);
+	BOOL adjustedCenterPoint = NO;
+	if (topPixelY > MERCATOR_OFFSET * 2) {
+		topPixelY = centerPixelY - scaledMapHeight;
+		bottomPixelY = MERCATOR_OFFSET * 2;
+		adjustedCenterPoint = YES;
+	}
+
+	// find delta between top and bottom latitudes
+	CLLocationDegrees minLat = [AIRMapManager pixelSpaceYToLatitude:topPixelY];
+	CLLocationDegrees maxLat = [AIRMapManager pixelSpaceYToLatitude:bottomPixelY];
+	CLLocationDegrees latitudeDelta = -1 * (maxLat - minLat);
+
+	// create and return the lat/lng span
+	MKCoordinateSpan span = MKCoordinateSpanMake(latitudeDelta, longitudeDelta);
+	MKCoordinateRegion region = MKCoordinateRegionMake(centerCoordinate, span);
+	// once again, MKMapView doesn’t like drawing boxes over the poles
+	// so adjust the center coordinate to the center of the resulting region
+	if (adjustedCenterPoint) {
+		region.center.latitude = [AIRMapManager pixelSpaceYToLatitude:((bottomPixelY + topPixelY) / 2.0)];
+	}
+
+	return region;
+}
+
+- (double) zoomLevel:(AIRMap *)mapView {
+    MKCoordinateRegion region = mapView.region;
+
+    double centerPixelX = [AIRMapManager longitudeToPixelSpaceX: region.center.longitude];
+    double topLeftPixelX = [AIRMapManager longitudeToPixelSpaceX: region.center.longitude - region.span.longitudeDelta / 2];
+
+    double scaledMapWidth = (centerPixelX - topLeftPixelX) * 2;
+    CGSize mapSizeInPixels = mapView.bounds.size;
+    double zoomScale = scaledMapWidth / mapSizeInPixels.width;
+    double zoomExponent = log(zoomScale) / log(2);
+    double zoomLevel = 20 - zoomExponent;
+
+    return zoomLevel;
+}
+
 @end