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Listen events for map touches

Introduction

Once you have implemented and set MapEventListener interface for MapView, this will get following events, with following data as their parameter value:

  • onMapMoved - map moving, zooming, tilting, rotating. Note that this is called for each pixel movement, so any work in this method can make map panning animation visibly slower.
  • onMapClicked(MapClickInfo) - map clicked, provides info about click:
    • ClickType - gives CLICK_TYPE_SINGLE, CLICK_TYPE_LONG, CLICK_TYPE_DOUBLE or CLICK_TYPE_DUAL
    • ClickPos - geographical click position (in map projection)
  • onVectorElementClicked(VectorElementsClickInfo) - any vector object on map was clicked (could be line,polygon,point,marker,balloon popup or a 3D model)
    • ClickType - see above
    • VectorElementClickInfos - sorted list of clicked objects, nearest is first. Each ClickInfo has:
    • ClickPos - geographical click location
    • ElementClickPos - click locaton projected to element, different from ClickPos if click was not precisely on object (hint: it never really is).
    • Distance - distance from the vector element to the camera
    • Order - order of element within VectorElementClickInfos
    • VectorElement - actual clicked element

1. Implement MapEventListener

Create new class called MyMapEventListener which implements MapEventListner interface.

// MyMapEventListener.h:

#import <Nuti/Nuti.h>

@interface  MyMapEventListener : NTMapEventListener
-(void)onMapMoved;
-(void)onMapClicked:(NTMapClickInfo*)mapClickInfo;
-(void)onVectorElementClicked:(NTVectorElementsClickInfo*)vectorElementsClickInfo;
@end


// MyMapEventListener.mm:

#import "MyMapEventListener.h"

@interface  MyMapEventListener() {
}
@end;

@implementation MyMapEventListener

-(void)onMapMoved
{
 // called very often, even just console logging can lag map movement animation
 // NSLog(@"Map moved!");
}

-(void)onMapClicked:(NTMapClickInfo*)mapClickInfo
{
    
    
    // Check the type of the click
    NSString* clickMsg;
    if ([mapClickInfo getClickType] == NT_CLICK_TYPE_SINGLE)
    {
        clickMsg = @"Single map click!";
    }
    else if ([mapClickInfo getClickType] == NT_CLICK_TYPE_LONG)
    {
        clickMsg = @"Long map click!";
    }
    else if ([mapClickInfo getClickType] == NT_CLICK_TYPE_DOUBLE)
    {
        clickMsg = @"Double map click!";
    }
    else if ([mapClickInfo getClickType] == NT_CLICK_TYPE_DUAL)
    {
        clickMsg = @"Dual map click!";
    }
    
    NTMapPos* clickPos = [mapClickInfo getClickPos];
    NTMapPos* wgs84Clickpos = [[[_mapView getOptions] getBaseProjection] toWgs84:clickPos];
    NSLog(@"%@ Location: %@", clickMsg, [NSString stringWithFormat:@"%f, %f", [wgs84Clickpos getY], [wgs84Clickpos getX]]);

}

-(void)onVectorElementClicked:(NTVectorElementsClickInfo*)vectorElementsClickInfo
{
    NSLog(@"Vector element click!");
    
    // Multiple vector elements can be clicked at the same time, we only care about the one
    // closest to the camera
    NTVectorElementClickInfo* clickInfo = [[vectorElementsClickInfo getVectorElementClickInfos] get:0];    
    
    // Load metadata from the object
    NTVectorElement* vectorElement = [clickInfo getVectorElement];
    NSString* clickText = [vectorElement getMetaDataElement:@"ClickText"];
    if (clickText == nil || [clickText length] == 0) {
        return;
    }
    
  NSLog(@"Vector element clicked, metadata : '%@'", clickText);

}

@end
// MyMapEventListener.java : 
// imports omitted...
/**
 * A custom map event listener that displays information about map events and creates pop-ups.
 */
public class MyMapEventListener extends MapEventListener {
    private MapView mapView;
    private LocalVectorDataSource vectorDataSource;
    
    private BalloonPopup oldClickLabel;
    
    public MyMapEventListener(MapView mapView, LocalVectorDataSource vectorDataSource) {
        this.mapView = mapView;
        this.vectorDataSource = vectorDataSource;
    }

    @Override
    public void onMapMoved() {

        final MapPos topLeft = mapView.screenToMap(new ScreenPos(0, 0));
        final MapPos bottomRight = mapView.screenToMap(new ScreenPos(mapView.getWidth(), mapView.getHeight()));
        Log.d(Const.LOG_TAG, mapView.getOptions().getBaseProjection().toWgs84(topLeft)
                + " " + mapView.getOptions().getBaseProjection().toWgs84(bottomRight));

    }

    @Override
    public void onMapClicked(MapClickInfo mapClickInfo) {
        Log.d(Const.LOG_TAG, "Map click!");
        
        // Remove old click label
        if (oldClickLabel != null) {
            vectorDataSource.remove(oldClickLabel);
            oldClickLabel = null;
        }
        
        BalloonPopupStyleBuilder styleBuilder = new BalloonPopupStyleBuilder();
        // Make sure this label is shown on top all other labels
        styleBuilder.setPlacementPriority(10);
        
        // Check the type of the click
        String clickMsg = null;
        if (mapClickInfo.getClickType() == ClickType.CLICK_TYPE_SINGLE) {
            clickMsg = "Single map click!";
        } else if (mapClickInfo.getClickType() == ClickType.CLICK_TYPE_LONG) {
            clickMsg = "Long map click!";
        } else if (mapClickInfo.getClickType() == ClickType.CLICK_TYPE_DOUBLE) {
            clickMsg = "Double map click!";
        } else if (mapClickInfo.getClickType() == ClickType.CLICK_TYPE_DUAL) {
            clickMsg ="Dual map click!";
        }
    
        MapPos clickPos = mapClickInfo.getClickPos();
        MapPos wgs84Clickpos = mapView.getOptions().getBaseProjection().toWgs84(clickPos);
        String msg = String.format(Locale.US, "%.4f, %.4f", wgs84Clickpos.getY(), wgs84Clickpos.getX());
        BalloonPopup clickPopup = new BalloonPopup(mapClickInfo.getClickPos(),
                                                   styleBuilder.buildStyle(),
                                                   clickMsg,
                                                   msg);
        vectorDataSource.add(clickPopup);
        oldClickLabel = clickPopup;
    }

    @Override
    public void onVectorElementClicked(VectorElementsClickInfo vectorElementsClickInfo) {
        Log.d(Const.LOG_TAG, "Vector element click!");
        
        // Remove old click label
        if (oldClickLabel != null) {
            vectorDataSource.remove(oldClickLabel);
            oldClickLabel = null;
        }
        
        // Multiple vector elements can be clicked at the same time, we only care about the one
        // closest to the camera
        VectorElementClickInfo clickInfo = vectorElementsClickInfo.getVectorElementClickInfos().get(0);
        
        // Check the type of vector element
        BalloonPopup clickPopup = null;
        BalloonPopupStyleBuilder styleBuilder = new BalloonPopupStyleBuilder();
        // Configure style
        styleBuilder.setLeftMargins(new BalloonPopupMargins(0, 0, 0, 0));
        styleBuilder.setTitleMargins(new BalloonPopupMargins(6, 3, 6, 3));
        // Make sure this label is shown on top all other labels
        styleBuilder.setPlacementPriority(10);

        VectorElement vectorElement = clickInfo.getVectorElement();
        String clickText = vectorElement.getMetaDataElement("ClickText");
        if (clickText == null || clickText.length() == 0) {
            return;
        }

        if (vectorElement instanceof Billboard) {
            // If the element is billboard, attach the click label to the billboard element
            Billboard billboard = (Billboard) vectorElement;
            clickPopup = new BalloonPopup(billboard, 
                                          styleBuilder.buildStyle(),
                                          clickText, 
                                          "");
        } else {
            // for lines and polygons set label to click location
            clickPopup = new BalloonPopup(clickInfo.getElementClickPos(),
                                          styleBuilder.buildStyle(),
                                          clickText,
                                          "");
        }
        vectorDataSource.add(clickPopup);
        oldClickLabel = clickPopup;
    }
}

// MapListener.cs :
// using statements skipped

namespace HelloMap
{

    public class MapListener : MapEventListener
    {
        private LocalVectorDataSource _dataSource;
        private BalloonPopup _oldClickLabel;

        public MapListener(LocalVectorDataSource dataSource)
        {
            _dataSource = dataSource;
        }

        public override void OnMapClicked (MapClickInfo mapClickInfo)
        {
            // Remove old click label
            if (_oldClickLabel != null) {
                _dataSource.Remove(_oldClickLabel);
                _oldClickLabel = null;
            }
        }

        public override void OnMapMoved()
        {
        }

        public override void OnVectorElementClicked(VectorElementsClickInfo vectorElementsClickInfo)
        {
            // A note about iOS: DISABLE 'Optimize PNG files for iOS' option in iOS build settings,
            // otherwise icons can not be loaded using AssetUtils/Bitmap constructor as Xamarin converts
            // PNGs to unsupported custom format.

            // Remove old click label
            if (_oldClickLabel != null) {
                _dataSource.Remove(_oldClickLabel);
                _oldClickLabel = null;
            }

            var clickInfo = vectorElementsClickInfo.VectorElementClickInfos[0];

            var styleBuilder = new BalloonPopupStyleBuilder();
            // Configure simple style
            styleBuilder.LeftMargins = new BalloonPopupMargins (0, 3, 0, 6);
            styleBuilder.RightMargins = new BalloonPopupMargins (0, 3, 0, 6);

            // Make sure this label is shown on top all other labels
            styleBuilder.PlacementPriority = 10;

            var vectorElement = clickInfo.VectorElement;
            var clickText = vectorElement.GetMetaDataElement("ClickText");

            var clickPopup = new BalloonPopup(clickInfo.ElementClickPos, 
                styleBuilder.BuildStyle(),
                clickText, 
                "");

            _dataSource.Add(clickPopup);
            _oldClickLabel = clickPopup;

        }
    }
}

2. Initialize listener

// 1. Create a map event listener
MyMapEventListener* mapListener = [[MyMapEventListener alloc] init];
[self setMapEventListener:mapListener];
    
 mapView.setMapEventListener(new MyMapEventListener(mapView, vectorDataSource));

 // Create and set map listener
 mapView.MapEventListener = new MapListener (dataSource);