Geojson performance
This example demonstrates how to handle the processing of large GeoJSON data efficiently without blocking the UI thread with the Maps SDK for Android. The LargeGeojsonPerformanceActivity class showcases the utilization of various Mapbox Maps SDK functionalities.
The activity loads a MapView and populates it with GeoJSON data, ensuring that the UI thread remains responsive during the parsing process. By using coroutines and worker threads, the GeoJSON data is converted to Feature objects without disrupting the user interface. The example also includes the addition of symbols and layers to the map, while logging updates and utilizing animations for a seamless user experience.
This example code is part of the Maps SDK for Android Examples App, a working Android project available on GitHub. Android developers are encouraged to run the examples app locally to interact with this example in an emulator and explore other features of the Maps SDK.
See our Run the Maps SDK for Android Examples App tutorial for step-by-step instructions.
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"
}
}