Add feature management functionality to MapPage and MapViewModel with feature creation, deletion, attribute updates, geometry updates, and dropdown UI component integration.

app/src/main/java/de/jadehs/strassenschadenpro2/MapViewModel.kt

@@ -1,26 +1,270 @@
 package de.jadehs.strassenschadenpro2
 
 import android.app.Application
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.unit.dp
 import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.viewModelScope
+import com.arcgismaps.LoadStatus
+import com.arcgismaps.data.ArcGISFeature
+import com.arcgismaps.data.CodedValueDomain
 import com.arcgismaps.data.ServiceFeatureTable
+import com.arcgismaps.geometry.GeometryEngine
 import com.arcgismaps.mapping.ArcGISMap
 import com.arcgismaps.mapping.BasemapStyle
 import com.arcgismaps.mapping.Viewpoint
 import com.arcgismaps.mapping.layers.FeatureLayer
+import com.arcgismaps.mapping.view.ScreenCoordinate
+import com.arcgismaps.mapping.view.SingleTapConfirmedEvent
 import com.arcgismaps.toolkit.geoviewcompose.MapViewProxy
 import de.jadehs.strassenschadenpro2.pages.SettingsPage
+import kotlinx.coroutines.launch
 
 class MapViewModel(application: Application): AndroidViewModel(application) {
-    val map: ArcGISMap = ArcGISMap(BasemapStyle.OpenOsmStyle)
-
+    val map: ArcGISMap = ArcGISMap(BasemapStyle.OpenOsmStyle).apply {
+        initialViewpoint = Viewpoint(53.14, 8.20, 20000.0)
+    }
+    // Hold a reference to the selected feature.
+    var selectedFeature: ArcGISFeature? by mutableStateOf(null)
     val mapViewProxy = MapViewProxy()
 
+    var currentFeatureOperation by mutableStateOf(FeatureOperationType.CREATE)
+
     lateinit var featureLayer: FeatureLayer
 
+    // Create a snackbar message to display the result of feature operations.
+    var snackBarMessage: String by mutableStateOf("")
+
+    lateinit var serviceFeatureTable: ServiceFeatureTable
+
+    var currentDamageType by mutableStateOf("")
+
+    // The list of damage types to update the feature attribute.
+    var damageTypeList: List<String> = mutableListOf()
+
     init {
-        val serviceFeatureTable = ServiceFeatureTable("https://services9.arcgis.com/UVxdrlZq3S3gqt7w/ArcGIS/rest/services/StrassenSchaeden/FeatureServer/0")
+        viewModelScope.launch {
+            serviceFeatureTable = ServiceFeatureTable("https://services9.arcgis.com/UVxdrlZq3S3gqt7w/ArcGIS/rest/services/StrassenSchaeden/FeatureServer/0")
+            serviceFeatureTable.load().onSuccess {
+                // Get the field from the feature table that will be updated.
+                val typeDamageField = serviceFeatureTable.fields.first { it.name == "Typ" }
+                // Get the coded value domain for the field.
+                val attributeDomain = typeDamageField.domain as CodedValueDomain
+                // Add the damage types to the list.
+                attributeDomain.codedValues.forEach {
+                    damageTypeList += it.name
+                }
+            }
             featureLayer = FeatureLayer.createWithFeatureTable(serviceFeatureTable)
             map.operationalLayers.add(featureLayer)
-        map.initialViewpoint = Viewpoint(53.14, 8.20, 20000.0)
+        }
+    }
+
+    /**
+     * Set the current feature operation to perform based on the selected index from the dropdown. Also, reset feature
+     * selection.
+     */
+    fun onFeatureOperationSelected(index: Int) {
+        currentFeatureOperation = FeatureOperationType.entries[index]
+        // Reset the selected feature when the operation changes.
+        featureLayer?.clearSelection()
+        selectedFeature = null
+    }
+
+    /**
+     * Directs the behaviour of tap's on the map view.
+     */
+    fun onTap(singleTapConfirmedEvent: SingleTapConfirmedEvent) {
+        if (featureLayer?.loadStatus?.value != LoadStatus.Loaded) {
+            snackBarMessage = "Layer not loaded!"
+            return
+        }
+        when (currentFeatureOperation) {
+            FeatureOperationType.CREATE -> createFeatureAt(singleTapConfirmedEvent.screenCoordinate)
+            FeatureOperationType.DELETE -> deleteFeatureAt(singleTapConfirmedEvent.screenCoordinate)
+            FeatureOperationType.UPDATE_ATTRIBUTE -> selectFeatureForAttributeEditAt(singleTapConfirmedEvent.screenCoordinate)
+            FeatureOperationType.UPDATE_GEOMETRY -> updateFeatureGeometryAt(singleTapConfirmedEvent.screenCoordinate)
+            else -> {}
+        }
+    }
+
+    /**
+     * Create a new feature at the tapped location with some default attributes
+     */
+    private fun createFeatureAt(screenCoordinate: ScreenCoordinate) {
+        // Create the feature.
+        val feature = serviceFeatureTable?.createFeature()?.apply {
+            // Get the normalized geometry for the tapped location and use it as the feature's geometry.
+            mapViewProxy.screenToLocationOrNull(screenCoordinate)?.let { mapPoint ->
+                geometry = GeometryEngine.normalizeCentralMeridian(mapPoint)
+                // Set feature attributes.
+                attributes["Typ"] = "SL"
+                attributes["Beschreibung"] = "Earthquake"
+            }
+        }
+        feature?.let {
+            viewModelScope.launch {
+                // Add the feature to the table.
+                serviceFeatureTable?.addFeature(it)
+                // Apply the edits to the service on the service geodatabase.
+                serviceFeatureTable?.applyEdits()
+                // Update the feature to get the updated objectid - a temporary ID is used before the feature is added.
+                it.refresh()
+                // Confirm feature addition.
+                snackBarMessage = "Created feature ${it.attributes["objectid"]}"
+            }
+        }
+    }
+
+    /**
+     * Selects a feature at the tapped location in preparation for deletion.
+     */
+    private fun deleteFeatureAt(screenCoordinate: ScreenCoordinate) {
+        featureLayer?.let { featureLayer ->
+            // Clear any existing selection.
+            featureLayer.clearSelection()
+            selectedFeature = null
+            viewModelScope.launch {
+                // Determine if a user tapped on a feature.
+                mapViewProxy.identify(featureLayer, screenCoordinate, 10.dp).onSuccess { identifyResult ->
+                    selectedFeature = (identifyResult.geoElements.firstOrNull() as? ArcGISFeature)?.also {
+                        featureLayer.selectFeature(it)
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Delete the selected feature from the feature table and service geodatabase.
+     */
+    fun deleteSelectedFeature() {
+        selectedFeature?.let {
+            // Get the feature's object id.
+            val featureId = it.attributes["objectid"] as Long
+            viewModelScope.launch {
+                // Delete the feature from the feature table.
+                serviceFeatureTable?.deleteFeature(it)?.onSuccess {
+                    snackBarMessage = "Deleted feature $featureId"
+                    // Apply the edits to the service geodatabase.
+                    serviceFeatureTable?.applyEdits()
+                    selectedFeature = null
+                }?.onFailure {
+                    snackBarMessage = "Failed to delete feature $featureId"
+                }
+            }
+        }
+    }
+
+    /**
+     * Selects a feature at the tapped location in preparation for attribute editing.
+     */
+    private fun selectFeatureForAttributeEditAt(screenCoordinate: ScreenCoordinate) {
+        featureLayer?.let { featureLayer ->
+            // Clear any existing selection.
+            featureLayer.clearSelection()
+            selectedFeature = null
+            viewModelScope.launch {
+                // Determine if a user tapped on a feature.
+                mapViewProxy.identify(featureLayer, screenCoordinate, 10.dp).onSuccess { identifyResult ->
+                    // Get the identified feature.
+                    val identifiedFeature = identifyResult.geoElements.firstOrNull() as? ArcGISFeature
+                    identifiedFeature?.let {
+                        val currentAttributeValue = it.attributes["Typ"] as String
+                        currentDamageType = currentAttributeValue
+                        selectedFeature = it.also {
+                            featureLayer.selectFeature(it)
+                        }
+                    } ?: run {
+                        // Reset damage type if no feature identified.
+                        currentDamageType = ""
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Update the attribute value of the selected feature to the new value from the new damage type.
+     */
+    fun onDamageTypeSelected(index: Int) {
+        // Get the new value.
+        currentDamageType = damageTypeList[index]
+        selectedFeature?.let { selectedFeature ->
+            viewModelScope.launch {
+                // Load the feature.
+                selectedFeature.load().onSuccess {
+                    // Update the attribute value.
+                    selectedFeature.attributes["Typ"] = currentDamageType
+                    // Update the table.
+                    serviceFeatureTable?.updateFeature(selectedFeature)
+                    // Update the service on the service geodatabase.
+                    serviceFeatureTable?.applyEdits()?.onSuccess {
+                        snackBarMessage =
+                            "Updated feature ${selectedFeature.attributes["objectid"]} to $currentDamageType"
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Select a feature, if none is selected. If a feature is selected, update its geometry to the tapped location.
+     */
+    private fun updateFeatureGeometryAt(screenCoordinate: ScreenCoordinate) {
+
+        featureLayer?.let { featureLayer ->
+            when (selectedFeature) {
+                // When no feature is selected.
+                null -> {
+                    viewModelScope.launch {
+                        // Determine if a user tapped on a feature.
+                        mapViewProxy.identify(featureLayer, screenCoordinate, 10.dp).onSuccess { identifyResult ->
+                            // Get the identified feature.
+                            val identifiedFeature = identifyResult.geoElements.firstOrNull() as? ArcGISFeature
+                            identifiedFeature?.let {
+                                selectedFeature = it.also {
+                                    featureLayer.selectFeature(it)
+                                }
+                            }
+                        }
+                    }
+                }
+                // When a feature is selected, update its geometry to the tapped location.
+                else -> {
+                    mapViewProxy.screenToLocationOrNull(screenCoordinate)?.let { mapPoint ->
+                        // Normalize the point - needed when the tapped location is over the international date line.
+                        val destinationPoint = GeometryEngine.normalizeCentralMeridian(mapPoint)
+                        viewModelScope.launch {
+                            selectedFeature?.let { selectedFeature ->
+                                // Load the feature.
+                                selectedFeature.load().onSuccess {
+                                    // Update the geometry of the selected feature.
+                                    selectedFeature.geometry = destinationPoint
+                                    // Apply the edit to the feature table.
+                                    serviceFeatureTable?.updateFeature(selectedFeature)
+                                    // Push the update to the service with the service geodatabase.
+                                    serviceFeatureTable?.applyEdits()?.onSuccess {
+                                        snackBarMessage = "Moved feature ${selectedFeature.attributes["objectid"]}"
+                                    }?.onFailure {
+                                        snackBarMessage =
+                                            "Failed to move feature ${selectedFeature.attributes["objectid"]}"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
     }
 }
+
+enum class FeatureOperationType(val operationName: String, val instruction: String) {
+    CREATE("Create feature", "Tap on the map to create a new feature."),
+    DELETE("Delete feature", "Select an existing feature to delete it."),
+    UPDATE_ATTRIBUTE("Update attribute", "Select an existing feature to edit its attribute."),
+    UPDATE_GEOMETRY("Update geometry", "Select an existing feature and tap the map to move it to a new position.")
+}

app/src/main/java/de/jadehs/strassenschadenpro2/components/DropDownMenuBox.kt

@@ -0,0 +1,83 @@
+
+
+/* Copyright 2025 Esri
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+@file:OptIn(ExperimentalMaterial3Api::class)
+
+package de.jadehs.strassenschadenpro2.components
+
+import android.content.res.Configuration
+import androidx.compose.material3.DropdownMenuItem
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.ExposedDropdownMenuBox
+import androidx.compose.material3.ExposedDropdownMenuDefaults
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.MenuAnchorType
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextField
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.tooling.preview.Preview
+
+/**
+ * Composable component to simplify the usage of an [ExposedDropdownMenuBox].
+ */
+@Composable
+fun DropDownMenuBox(
+    modifier: Modifier = Modifier,
+    textFieldValue: String,
+    textFieldLabel: String,
+    dropDownItemList: List<String>,
+    onIndexSelected: (Int) -> Unit
+) {
+    var expanded by remember { mutableStateOf(false) }
+    ExposedDropdownMenuBox(
+        modifier = modifier,
+        expanded = expanded,
+        onExpandedChange = { expanded = !expanded }
+    ) {
+        TextField(
+            label = { Text(textFieldLabel) },
+            value = textFieldValue,
+            onValueChange = {},
+            readOnly = true,
+            trailingIcon = { ExposedDropdownMenuDefaults.TrailingIcon(expanded = expanded) },
+            modifier = Modifier.menuAnchor(type = MenuAnchorType.PrimaryNotEditable)
+        )
+        ExposedDropdownMenu(
+            expanded = expanded,
+            onDismissRequest = { expanded = false }
+        ) {
+            dropDownItemList.forEachIndexed { index, scalebarStyle ->
+                DropdownMenuItem(
+                    text = { Text(scalebarStyle) },
+                    onClick = {
+                        onIndexSelected(index)
+                        expanded = false
+                    })
+                // Show a divider between dropdown menu options
+                if (index < dropDownItemList.lastIndex) {
+                    HorizontalDivider()
+                }
+            }
+        }
+    }
+}

app/src/main/java/de/jadehs/strassenschadenpro2/pages/MapPage.kt

@@ -7,14 +7,23 @@ import android.content.pm.PackageManager
 import android.widget.Toast
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
 import com.arcgismaps.ApiKey
 import com.arcgismaps.ArcGISEnvironment
@@ -25,7 +34,9 @@ import com.arcgismaps.mapping.Viewpoint
 import com.arcgismaps.toolkit.geoviewcompose.MapView
 import com.arcgismaps.toolkit.geoviewcompose.rememberLocationDisplay
 import de.jadehs.strassenschadenpro2.BuildConfig
+import de.jadehs.strassenschadenpro2.FeatureOperationType
 import de.jadehs.strassenschadenpro2.MapViewModel
+import de.jadehs.strassenschadenpro2.components.DropDownMenuBox
 import kotlinx.coroutines.launch
 
 @Composable
@@ -33,9 +44,13 @@ fun MapPage(modifier: Modifier = Modifier, application: Application) {
     val context = LocalContext.current
     val coroutineScope = rememberCoroutineScope()
 
+    var featureManagementDropdownIndex by remember { mutableIntStateOf(0) }
+
     ArcGISEnvironment.applicationContext = context.applicationContext
     ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.ARCGIS_TOKEN)
 
+    val snackbarHostState = remember { SnackbarHostState() }
+
     val locationDisplay = rememberLocationDisplay().apply {
         setAutoPanMode(LocationDisplayAutoPanMode.Off)
     }
@@ -58,10 +73,60 @@ fun MapPage(modifier: Modifier = Modifier, application: Application) {
 
     val mapViewModel = remember { MapViewModel(application) }
 
-    MapView(modifier = Modifier.fillMaxSize(),
+    Column(
+        modifier = Modifier
+            .fillMaxSize(),
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        MapView(
+            modifier = Modifier.weight(80f),
             arcGISMap = mapViewModel.map,
-        locationDisplay = locationDisplay
+            locationDisplay = locationDisplay,
+            mapViewProxy = mapViewModel.mapViewProxy,
+            onSingleTapConfirmed = mapViewModel::onTap,
+        ) {
+            mapViewModel.selectedFeature?.let { selectedFeature ->
+                // Only show the delete button when on the delete feature operation and a feature is selected.
+                if (mapViewModel.currentFeatureOperation == FeatureOperationType.DELETE) {
+                    Callout(geoElement = selectedFeature) {
+                        Button(onClick = mapViewModel::deleteSelectedFeature) {
+                            Text(text = "Delete")
+                        }
+                    }
+                }
+                // Only show the dropdown for damage type when on the update feature operation.
+                if (mapViewModel.currentFeatureOperation == FeatureOperationType.UPDATE_ATTRIBUTE) {
+                    Callout(geoElement = selectedFeature) {
+                        DropDownMenuBox(
+                            modifier = Modifier
+                                .padding(8.dp),
+                            textFieldLabel = "Select damage type",
+                            textFieldValue = mapViewModel.currentDamageType,
+                            dropDownItemList = mapViewModel.damageTypeList,
+                            onIndexSelected = { index ->
+                                if (mapViewModel.selectedFeature != null) {
+                                    mapViewModel.onDamageTypeSelected(index)
+                                } else {
+                                    coroutineScope.launch {
+                                        snackbarHostState.showSnackbar("Please select a feature to update")
+                                    }
+                                }
+                            }
                         )
+                    }
+                }
+            }
+        }
+        DropDownMenuBox(
+            modifier = Modifier.weight(20f).padding(end = 8.dp),
+            textFieldLabel = "Feature management operation",
+            textFieldValue = mapViewModel.currentFeatureOperation.operationName,
+            dropDownItemList = FeatureOperationType.entries.map { entry -> entry.operationName },
+            onIndexSelected = { index ->
+                mapViewModel.onFeatureOperationSelected(index)
+                featureManagementDropdownIndex = index
+            })
+    }
 }
 
 fun checkPermissions(context: Context): Boolean {