Geojson performance | Maps SDK | Android Docs

Display long route as large geojson.
Kotlin
LargeGeojsonPerformanceActivity.kt
package com.mapbox.maps.testapp.examples

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.core.content.ContextCompat
import androidx.core.graphics.drawable.toBitmap
import androidx.lifecycle.lifecycleScope
import com.mapbox.geojson.Feature
import com.mapbox.geojson.Point
import com.mapbox.maps.CameraOptions
import com.mapbox.maps.MapView
import com.mapbox.maps.MapboxStyleManager
import com.mapbox.maps.Style
import com.mapbox.maps.extension.style.image.image
import com.mapbox.maps.extension.style.layers.addLayer
import com.mapbox.maps.extension.style.layers.generated.lineLayer
import com.mapbox.maps.extension.style.layers.generated.symbolLayer
import com.mapbox.maps.extension.style.layers.properties.generated.IconAnchor
import com.mapbox.maps.extension.style.sources.addSource
import com.mapbox.maps.extension.style.sources.generated.geoJsonSource
import com.mapbox.maps.extension.style.style
import com.mapbox.maps.logI
import com.mapbox.maps.plugin.animation.MapAnimationOptions
import com.mapbox.maps.plugin.animation.flyTo
import com.mapbox.maps.testapp.R
import com.mapbox.maps.testapp.examples.annotation.AnnotationUtils
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext

/**
 * Example of passing large geojson to verify it does not block UI thread
 * for parsing before passed to core.
 */
class LargeGeojsonPerformanceActivity : AppCompatActivity() {

  private var jsonUpdateCounter = 0

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val mapView = MapView(this)
    setContentView(mapView)

    mapView.mapboxMap.apply {
      subscribeSourceDataLoaded {
        if (it.dataId.isNullOrBlank().not()) {
          // log whenever update with corresponding data-id is rendered on the map
          logI(TAG, "GeoJsonSource was updated, data-id : ${it.dataId}")
        }
      }

      setCamera(
        CameraOptions.Builder()
          .center(Point.fromLngLat(LONGITUDE, LATITUDE))
          .zoom(START_ZOOM)
          .build()
      )
      loadStyle(
        style(Style.STANDARD) {
          // add an icon that uses very small geojson source
          +image(
            "icon",
            ContextCompat.getDrawable(
              this@LargeGeojsonPerformanceActivity,
              R.drawable.ic_blue_marker
            )!!.toBitmap()
          )
          +geoJsonSource("${SOURCE}_marker") {
            logI(TAG, "Update marker ${SOURCE}_marker, data-id : $jsonUpdateCounter")
            geometry(Point.fromLngLat(LONGITUDE, LATITUDE), jsonUpdateCounter++.toString())
          }
          +symbolLayer("${LAYER}_marker", "${SOURCE}_marker") {
            iconImage("icon")
            iconAnchor(IconAnchor.BOTTOM)
          }
        }
      ) {
        lifecycleScope.launch {
          // start an animation that uses UI thread to update map camera
          flyTo(
            CameraOptions.Builder().zoom(END_ZOOM).build(),
            MapAnimationOptions.mapAnimationOptions { duration(ANIMATION_DURATION_MS) }
          )
          // Converting a big String to Feature takes some time so we'll do it in a worker thread
          val routePoints = withContext(Dispatchers.Default) {
            Feature.fromJson(
              AnnotationUtils.loadStringFromAssets(
                this@LargeGeojsonPerformanceActivity,
                LARGE_GEOJSON_ASSET_NAME
              )
            )
          }

          addGeoJsonLines(routePoints, mapView.mapboxMap)
        }
      }
    }
  }

  private fun addGeoJsonLines(routePoints: Feature, mapboxStyleManager: MapboxStyleManager) {
    repeat(LARGE_SOURCE_COUNT) {
      mapboxStyleManager.addSource(
        geoJsonSource("${SOURCE}_$it") {
          logI(TAG, "Update routePoints ${SOURCE}_$it, data-id : $jsonUpdateCounter")
          feature(routePoints, jsonUpdateCounter++.toString())
        }
      )
      mapboxStyleManager.addLayer(
        lineLayer("${LAYER}_$it", "${SOURCE}_$it") {
          lineColor("blue")
          lineOffset(5.0 * it)
        }
      )
    }
  }

  companion object {
    private const val LARGE_GEOJSON_ASSET_NAME = "long_route.json"
    private const val ANIMATION_DURATION_MS = 10_000L
    private const val SOURCE = "source"
    private const val LAYER = "layer"
    private const val LARGE_SOURCE_COUNT = 6
    private const val LATITUDE = 51.1079
    private const val LONGITUDE = 17.0385
    private const val START_ZOOM = 5.9
    private const val END_ZOOM = 2.0
    private const val TAG = "LargeGeojsonUpdate"
  }
}
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