core: add CustomVectorSource for binary tile data delivery (#4377)
Co-authored-by: Vladyslav Odobesku <VladyslavOdobesku@intellias.com> Co-authored-by: Claude Opus 4 <noreply@anthropic.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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Vladyslav Odobesku
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25e4f6acbf
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9ef0f1c790
@@ -746,6 +746,18 @@
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android:name="android.support.PARENT_ACTIVITY"
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android:value=".activity.FeatureOverviewActivity" />
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</activity>
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<activity
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android:name=".activity.style.CustomVectorSourceActivity"
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android:description="@string/description_custom_vector_source"
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android:exported="true"
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android:label="@string/activity_custom_vector_source">
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<meta-data
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android:name="@string/category"
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android:value="@string/category_style" />
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<meta-data
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android:name="android.support.PARENT_ACTIVITY"
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android:value=".activity.FeatureOverviewActivity" />
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</activity>
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<activity
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android:name=".activity.style.NoStyleActivity"
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android:description="@string/description_no_style"
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@@ -0,0 +1,238 @@
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package org.maplibre.android.testapp.activity.style
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import android.graphics.Color
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import android.os.Bundle
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import android.widget.Toast
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import androidx.appcompat.app.AppCompatActivity
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import com.google.android.material.floatingactionbutton.FloatingActionButton
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import kotlinx.coroutines.CoroutineScope
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import kotlinx.coroutines.Dispatchers
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import kotlinx.coroutines.SupervisorJob
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import kotlinx.coroutines.cancel
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import kotlinx.coroutines.delay
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import org.maplibre.android.maps.MapView
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import org.maplibre.android.maps.MapLibreMap
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import org.maplibre.android.maps.OnMapReadyCallback
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import org.maplibre.android.maps.Style
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import org.maplibre.android.style.layers.LineLayer
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import org.maplibre.android.style.layers.PropertyFactory
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import org.maplibre.android.style.sources.CustomVectorSource
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import org.maplibre.android.style.sources.TileData
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import org.maplibre.android.style.sources.CustomVectorTileProvider
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import org.maplibre.android.testapp.R
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import org.maplibre.android.testapp.styles.TestStyles
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import java.io.ByteArrayOutputStream
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/**
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* Demo activity that uses CustomVectorSource with a fake MVT tile provider.
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* Generates a diagonal cross pattern per tile as synthetic MVT data.
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* Toggle the source on/off with the FAB.
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*/
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class CustomVectorSourceActivity : AppCompatActivity(), OnMapReadyCallback {
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private lateinit var mapView: MapView
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private var maplibreMap: MapLibreMap? = null
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private var sourceActive = false
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private val tileScope = CoroutineScope(SupervisorJob() + Dispatchers.IO)
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override fun onCreate(savedInstanceState: Bundle?) {
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super.onCreate(savedInstanceState)
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setContentView(R.layout.activity_custom_vector_source)
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mapView = findViewById(R.id.mapView)
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mapView.onCreate(savedInstanceState)
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mapView.getMapAsync(this)
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findViewById<FloatingActionButton>(R.id.fabToggle).setOnClickListener {
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toggleSource()
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}
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}
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override fun onMapReady(map: MapLibreMap) {
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maplibreMap = map
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map.setStyle(Style.Builder().fromUri(TestStyles.DEMOTILES))
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}
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private fun toggleSource() {
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val map = maplibreMap ?: return
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val style = map.style ?: return
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if (sourceActive) {
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style.removeLayer(LAYER_ID)
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style.removeSource(SOURCE_ID)
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sourceActive = false
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Toast.makeText(this, "CustomVectorSource removed", Toast.LENGTH_SHORT).show()
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} else {
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val source = CustomVectorSource(SOURCE_ID, DiagonalTileProvider(), tileScope, minZoom = 0, maxZoom = 14)
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val layer = LineLayer(LAYER_ID, SOURCE_ID).apply {
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setSourceLayer(SOURCE_LAYER_NAME)
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setProperties(
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PropertyFactory.lineColor(Color.RED),
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PropertyFactory.lineWidth(2f),
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PropertyFactory.lineOpacity(0.8f)
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)
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}
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style.addSource(source)
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style.addLayer(layer)
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sourceActive = true
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Toast.makeText(this, "CustomVectorSource added", Toast.LENGTH_SHORT).show()
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}
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}
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/**
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* A fake tile provider that generates MVT tiles containing diagonal lines.
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* Simulates async work with a small delay.
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*/
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private class DiagonalTileProvider : CustomVectorTileProvider {
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override suspend fun fetchTile(z: Int, x: Int, y: Int): TileData {
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// Simulate network latency
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delay(50)
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val mvtBytes = buildDiagonalMvtTile(z, x, y)
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return TileData.Mvt(mvtBytes)
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}
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}
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override fun onStart() { super.onStart(); mapView.onStart() }
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override fun onResume() { super.onResume(); mapView.onResume() }
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override fun onPause() { super.onPause(); mapView.onPause() }
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override fun onStop() { super.onStop(); mapView.onStop() }
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override fun onDestroy() { tileScope.cancel(); super.onDestroy(); mapView.onDestroy() }
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override fun onSaveInstanceState(outState: Bundle) {
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super.onSaveInstanceState(outState)
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mapView.onSaveInstanceState(outState)
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}
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companion object {
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const val SOURCE_ID = "custom-vector-source"
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const val LAYER_ID = "custom-vector-layer"
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const val SOURCE_LAYER_NAME = "diagonal"
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private const val EXTENT = 4096
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/**
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* Builds a minimal MVT tile with two diagonal lines forming an X.
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* MVT protobuf encoding done by hand (no protobuf library needed).
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*/
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private fun buildDiagonalMvtTile(z: Int, x: Int, y: Int): ByteArray {
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// Geometry: two lines forming an X across the tile
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// Line 1: (0,0) -> (4096,4096)
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// Line 2: (4096,0) -> (0,4096)
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val geom1 = encodeMvtGeometry(
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listOf(Pair(0, 0), Pair(EXTENT, EXTENT))
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)
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val geom2 = encodeMvtGeometry(
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listOf(Pair(EXTENT, 0), Pair(0, EXTENT))
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)
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// Also add a border rectangle
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val border = encodeMvtGeometry(
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listOf(Pair(0, 0), Pair(EXTENT, 0), Pair(EXTENT, EXTENT), Pair(0, EXTENT), Pair(0, 0))
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)
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val feature1 = encodeMvtFeature(id = 1, geometry = geom1, geomType = 2)
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val feature2 = encodeMvtFeature(id = 2, geometry = geom2, geomType = 2)
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val feature3 = encodeMvtFeature(id = 3, geometry = border, geomType = 2)
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val layer = encodeMvtLayer(
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name = SOURCE_LAYER_NAME,
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extent = EXTENT,
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features = listOf(feature1, feature2, feature3)
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)
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// Tile: repeated Layer layers = 3;
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val tile = ByteArrayOutputStream()
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writeTag(tile, 3, 2) // field 3, wire type 2 (length-delimited)
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writeBytes(tile, layer)
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return tile.toByteArray()
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}
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private fun encodeMvtGeometry(points: List<Pair<Int, Int>>): ByteArray {
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val commands = mutableListOf<Int>()
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for (i in points.indices) {
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if (i == 0) {
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// MoveTo command: id=1, count=1
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commands.add(commandInteger(1, 1))
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commands.add(zigzag(points[0].first))
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commands.add(zigzag(points[0].second))
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} else {
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if (i == 1) {
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// LineTo command: id=2, count=remaining points
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commands.add(commandInteger(2, points.size - 1))
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}
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val dx = points[i].first - points[i - 1].first
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val dy = points[i].second - points[i - 1].second
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commands.add(zigzag(dx))
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commands.add(zigzag(dy))
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}
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}
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return commands.flatMap { encodeVarint(it) }.toByteArray()
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}
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private fun encodeMvtFeature(id: Long, geometry: ByteArray, geomType: Int): ByteArray {
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val out = ByteArrayOutputStream()
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// optional uint64 id = 1
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writeTag(out, 1, 0)
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writeVarint(out, id)
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// optional GeomType type = 3
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writeTag(out, 3, 0)
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writeVarint(out, geomType.toLong())
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// repeated uint32 geometry = 4 (packed)
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writeTag(out, 4, 2)
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writeBytes(out, geometry)
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return out.toByteArray()
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}
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private fun encodeMvtLayer(name: String, extent: Int, features: List<ByteArray>): ByteArray {
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val out = ByteArrayOutputStream()
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// required uint32 version = 15
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writeTag(out, 15, 0)
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writeVarint(out, 2)
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// required string name = 1
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writeTag(out, 1, 2)
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writeBytes(out, name.toByteArray(Charsets.UTF_8))
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// repeated Feature features = 2
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for (feature in features) {
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writeTag(out, 2, 2)
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writeBytes(out, feature)
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}
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// optional uint32 extent = 5
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writeTag(out, 5, 0)
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writeVarint(out, extent.toLong())
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return out.toByteArray()
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}
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private fun commandInteger(id: Int, count: Int): Int = (id and 0x7) or (count shl 3)
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private fun zigzag(value: Int): Int = (value shl 1) xor (value shr 31)
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private fun encodeVarint(value: Int): List<Byte> {
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val bytes = mutableListOf<Byte>()
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var v = value.toLong() and 0xFFFFFFFFL
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while (v > 0x7F) {
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bytes.add(((v and 0x7F) or 0x80).toByte())
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v = v ushr 7
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}
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bytes.add((v and 0x7F).toByte())
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return bytes
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}
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private fun writeTag(out: ByteArrayOutputStream, fieldNumber: Int, wireType: Int) {
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writeVarint(out, ((fieldNumber shl 3) or wireType).toLong())
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}
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private fun writeVarint(out: ByteArrayOutputStream, value: Long) {
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var v = value
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while (v > 0x7F) {
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out.write(((v and 0x7F) or 0x80).toInt())
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v = v ushr 7
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}
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out.write((v and 0x7F).toInt())
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}
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private fun writeBytes(out: ByteArrayOutputStream, data: ByteArray) {
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writeVarint(out, data.size.toLong())
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out.write(data)
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}
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private fun List<Byte>.toByteArray(): ByteArray = ByteArray(size) { this[it] }
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}
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}
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@@ -0,0 +1,25 @@
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<?xml version="1.0" encoding="utf-8"?>
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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
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xmlns:app="http://schemas.android.com/apk/res-auto"
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android:layout_width="match_parent"
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android:layout_height="match_parent">
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<org.maplibre.android.maps.MapView
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android:id="@id/mapView"
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android:layout_width="match_parent"
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android:layout_height="match_parent"
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app:maplibre_cameraTargetLat="48.85"
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app:maplibre_cameraTargetLng="2.35"
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app:maplibre_cameraZoom="4"/>
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<com.google.android.material.floatingactionbutton.FloatingActionButton
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android:id="@+id/fabToggle"
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android:layout_width="wrap_content"
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android:layout_height="wrap_content"
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android:layout_alignParentBottom="true"
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android:layout_alignParentEnd="true"
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android:layout_margin="16dp"
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android:src="@android:drawable/ic_input_add"
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android:contentDescription="Toggle custom source"/>
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</RelativeLayout>
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@@ -83,6 +83,7 @@
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<string name="description_surfaceview_resize">Resize a map rendered on a SurfaceView</string>
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<string name="description_overlay">Blend an overlay on a map</string>
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<string name="description_grid_source">Example Custom Geometry Source</string>
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<string name="description_custom_vector_source">CustomVectorSource with synthetic MVT tiles</string>
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<string name="description_no_style">Load a map without providing a style URI or JSON</string>
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<string name="description_vector_tile">Load MVT data</string>
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<string name="description_pmtiles">Load PMTiles data</string>
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@@ -79,6 +79,7 @@
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<string name="activity_surfaceview_resize">SurfaceView resize</string>
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<string name="activity_overlay">Map overlay</string>
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<string name="activity_grid_source">Grid Source</string>
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<string name="activity_custom_vector_source">Custom Vector Source</string>
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<string name="activity_no_style">No Style URI/JSON</string>
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<string name="activity_vector_tile">Vector Tile source</string>
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<string name="activity_pmtiles">PMTiles</string>
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