Mapbox dragging

MapboxExtensions.kt

fun MapboxMap.resolveSymbolId(location: LatLng) = resolveAnnotationId(location, SymbolManager.ID_GEOJSON_LAYER)

fun MapboxMap.resolveSymbolId(screenLocation: PointF) = resolveAnnotationId(screenLocation, SymbolManager.ID_GEOJSON_LAYER)

/**
 * Check if an annotation is located at a given coordinate.
 *
 * @param location click location in real world coordinates
 *
 * @return annotation ID if an annotation exists, null otherwise
 */
private fun MapboxMap.resolveAnnotationId(location: LatLng, vararg layerIds: String): Long? =
		resolveAnnotationId(projection.toScreenLocation(location), *layerIds)

/**
 * Check if an annotation is located at a given coordinate.
 *
 * @param screenLocation click location in device coordinates
 *
 * @return annotation ID if an annotation exists, null otherwise
 */
private fun MapboxMap.resolveAnnotationId(screenLocation: PointF, vararg layerIds: String): Long?
{
	val features = queryRenderedFeatures(screenLocation, *layerIds)
	if (features.isNotEmpty())
	{
		return features[0].getProperty("id").asLong
	}
	return null
}

SymbolDraggingHandler.kt

import android.graphics.PointF
import android.view.MotionEvent
import android.view.View
import com.anfema.pingonaut.utils.Log
import com.anfema.pingonaut.utils.resolveSymbolId
import com.mapbox.mapboxsdk.maps.MapboxMap
import com.mapbox.mapboxsdk.plugins.annotation.OnSymbolDragListener
import com.mapbox.mapboxsdk.plugins.annotation.Symbol
import com.mapbox.mapboxsdk.plugins.annotation.SymbolManager

/**
 * Make a single symbol draggable.
 *
 * @param onSymbolDragListener optional interface to receive dragging callback events
 */
class SymbolDraggingHandler(private val mapBox: MapboxMap, private val symbolManager: SymbolManager, private val onSymbolDragListener: OnSymbolDragListener?) : View.OnTouchListener
{
	var symbol: Symbol? = null

	private var touchDelta = PointF() // initial distance of touch event to anchor of symbol icon
	private var isDragged: Boolean = false

	override fun onTouch(v: View?, event: MotionEvent): Boolean
	{
		val symbol = symbol ?: return false

		val action = event.actionMasked
		if (action == MotionEvent.ACTION_DOWN)
		{
			if (isSymbolTouched(event, symbol))
			{
				isDragged = true
				val initialScreenLocation = mapBox.projection.toScreenLocation(symbol.latLng)
				touchDelta.apply {
					x = initialScreenLocation.x - event.x
					y = initialScreenLocation.y - event.y
				}
			}
		}
		if (isDragged)
		{
			if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP)
			{
				isDragged = false
				onSymbolDragListener?.onAnnotationDragFinished(symbol)
			}
			else
			{
				val latLng = mapBox.projection.fromScreenLocation(PointF(event.x + touchDelta.x, event.y + touchDelta.y))
				symbol.latLng = latLng
				symbolManager.update(symbol)
				Log.d("Marker", "position $latLng")
				onSymbolDragListener?.onAnnotationDrag(symbol)
			}
			return true
		}
		else
		{
			return false
		}
	}

	private fun isSymbolTouched(event: MotionEvent, symbol: Symbol) = mapBox.resolveSymbolId(PointF(event.x, event.y)) == symbol.id
}