Apply Common Design to Add Feature Collection Layer from Table Sample (#89)

jenmerritt · web-flow · commit 48a737010a85 · 2024-07-24T17:06:57.000+01:00
* Update the sample

* Add README

* Add screen capture

* Generate metadata

* regenerate samples list

* Update add_feature_collection_layer_from_table.png

* use cascade

* Update README.md

* ArcGISPoint
diff --git a/assets/generated_samples_list.json b/assets/generated_samples_list.json
@@ -3,11 +3,33 @@
     "category": "Layers",
     "description": "Create a Feature Collection Layer from a Feature Collection Table, and add it to a map.",
     "ignore": false,
-    "images": [],
-    "keywords": [],
+    "images": [
+      "add_feature_collection_layer_from_table.png"
+    ],
+    "keywords": [
+      "collection",
+      "feature",
+      "layers",
+      "table",
+      "Feature",
+      "FeatureCollection",
+      "FeatureCollectionLayer",
+      "FeatureCollectionTable",
+      "Field",
+      "SimpleRenderer"
+    ],
     "redirect_from": [],
-    "relevant_apis": [],
-    "snippets": [],
+    "relevant_apis": [
+      "Feature",
+      "FeatureCollection",
+      "FeatureCollectionLayer",
+      "FeatureCollectionTable",
+      "Field",
+      "SimpleRenderer"
+    ],
+    "snippets": [
+      "add_feature_collection_layer_from_table_sample.dart"
+    ],
     "title": "Add feature collection layer from table",
     "key": "add_feature_collection_layer_from_table"
   },
diff --git a/lib/samples/add_feature_collection_layer_from_table/README.md b/lib/samples/add_feature_collection_layer_from_table/README.md
@@ -0,0 +1,36 @@
+# Add feature collection layer from table
+
+Create a Feature Collection Layer from a Feature Collection Table, and add it to a map.
+
+![Image of add feature collection layer from table](add_feature_collection_layer_from_table.png)
+
+## Use case
+
+A Feature Collection allows easily importing external data (such as CSV files), as well as creating custom schema for data that is in non-standardized format. This data can then be used to populate a Feature Collection Table, and displayed in a Feature Collection Layer using the attributes and geometries provided in the external data source. For example, an electricity supplier could use this functionality to visualize existing location data of coverage areas (polygons), power stations (points), transmission lines (polylines), and others.
+
+## How to use the sample
+
+When launched, this sample displays a `FeatureCollectionLayer` with a `ArcGISPoint`, `Polyline` and `Polygon` geometry. Pan and zoom to explore the scene.
+
+## How it works
+
+1. Create a `FeatureCollectionTable` for the `GeometryType`s `ArcGISPoint`, `Polyline`, and `Polygon`, using `FeatureCollectionTable(fields, geometryType, spatialReference)`, passing in a list of `Field` objects to represent the table's schema, the `GeometryType`, and a `SpatialReference`.
+2. Assign a `SimpleRenderer` to each table to render any `Feature`s from that table using the `Symbol` that was set.
+3. Use the `FeatureCollectionTable.createFeature(attributes, geometry)` method to create a feature from the feature collection table, passing an attribute and geometry for that feature.
+4. Add new features to the table, `FeatureCollectionTable.addFeature(feature)`.
+5. Add the feature collection table to the feature collection, `FeatureCollection.tables.add(featureCollectionTable)`.
+6. Create a `FeatureCollectionLayer` using the feature collection, `FeatureCollectionLayer.withFeatureCollection(featureCollection)`.
+7. Add the feature collection layer to the map, `ArcGISMap.operationalLayers.add(featureCollectionLayer)`.
+
+## Relevant API
+
+* Feature
+* FeatureCollection
+* FeatureCollectionLayer
+* FeatureCollectionTable
+* Field
+* SimpleRenderer
+
+## Tags
+
+collection, feature, layers, table
diff --git a/lib/samples/add_feature_collection_layer_from_table/README.metadata.json b/lib/samples/add_feature_collection_layer_from_table/README.metadata.json
@@ -2,10 +2,32 @@
     "category": "Layers",
     "description": "Create a Feature Collection Layer from a Feature Collection Table, and add it to a map.",
     "ignore": false,
-    "images": [],
-    "keywords": [],
+    "images": [
+        "add_feature_collection_layer_from_table.png"
+    ],
+    "keywords": [
+        "collection",
+        "feature",
+        "layers",
+        "table",
+        "Feature",
+        "FeatureCollection",
+        "FeatureCollectionLayer",
+        "FeatureCollectionTable",
+        "Field",
+        "SimpleRenderer"
+    ],
     "redirect_from": [],
-    "relevant_apis": [],
-    "snippets": [],
+    "relevant_apis": [
+        "Feature",
+        "FeatureCollection",
+        "FeatureCollectionLayer",
+        "FeatureCollectionTable",
+        "Field",
+        "SimpleRenderer"
+    ],
+    "snippets": [
+        "add_feature_collection_layer_from_table_sample.dart"
+    ],
     "title": "Add feature collection layer from table"
 }
diff --git a/lib/samples/add_feature_collection_layer_from_table/add_feature_collection_layer_from_table.png b/lib/samples/add_feature_collection_layer_from_table/add_feature_collection_layer_from_table.png
diff --git a/lib/samples/add_feature_collection_layer_from_table/add_feature_collection_layer_from_table_sample.dart b/lib/samples/add_feature_collection_layer_from_table/add_feature_collection_layer_from_table_sample.dart
@@ -29,55 +29,63 @@ class AddFeatureCollectionLayerFromTableSample extends StatefulWidget {
 class _AddFeatureCollectionLayerFromTableSampleState
     extends State<AddFeatureCollectionLayerFromTableSample>
     with SampleStateSupport {
-  final _featureCollection = FeatureCollection();
+  // Create a controller for the map view.
   final _mapViewController = ArcGISMapView.createController();
 
-  _AddFeatureCollectionLayerFromTableSampleState() {
-    createPointTable();
-    createPolylineTable();
-    createPolygonTable();
-  }
-
-  @override
-  void initState() {
-    super.initState();
-
-    final map = ArcGISMap.withBasemapStyle(BasemapStyle.arcGISOceans);
-
-    map.initialViewpoint = Viewpoint.fromTargetExtent(
-      Envelope.fromXY(
-        xMin: -8917856.590171767,
-        yMin: 903277.583136797,
-        xMax: -8800611.655131537,
-        yMax: 1100327.8941287803,
-        spatialReference: SpatialReference(wkid: 102100),
-      ),
-    );
-
-    map.operationalLayers
-        .add(FeatureCollectionLayer.withFeatureCollection(_featureCollection));
-
-    _mapViewController.arcGISMap = map;
-  }
-
   @override
   Widget build(BuildContext context) {
     return Scaffold(
+      // Add a map view to the widget tree and set a controller.
       body: ArcGISMapView(
         controllerProvider: () => _mapViewController,
+        onMapViewReady: onMapViewReady,
       ),
     );
   }
 
-  void createPointTable() {
+  void onMapViewReady() {
+    // Create a feature collection table for each of the geometry types Point, Polyline, and Polygon.
+    final pointTable = createPointTable();
+    final polylineTable = createPolylineTable();
+    final polygonTable = createPolygonTable();
+
+    // Create a new feature collection and add the feature collection tables.
+    final featureCollection = FeatureCollection()
+      ..tables.addAll([pointTable, polylineTable, polygonTable]);
+
+    // Create a feature collection layer from the feature collection.
+    final featureCollectionLayer =
+        FeatureCollectionLayer.withFeatureCollection(featureCollection);
+
+    // Create a map with a basemap style and initial viewpoint.
+    final map = ArcGISMap.withBasemapStyle(BasemapStyle.arcGISOceans)
+      ..initialViewpoint = Viewpoint.fromTargetExtent(
+        Envelope.fromXY(
+          xMin: -8917856.590171767,
+          yMin: 903277.583136797,
+          xMax: -8800611.655131537,
+          yMax: 1100327.8941287803,
+          spatialReference: SpatialReference(wkid: 102100),
+        ),
+      );
+
+    // Add the feature collection layer to the map's operational layers.
+    map.operationalLayers.add(featureCollectionLayer);
+
+    // Set the map to the map view controller.
+    _mapViewController.arcGISMap = map;
+  }
+
+  // Create a feature collection table using a point geometry.
+  FeatureCollectionTable createPointTable() {
+    // Create a feature collection table for the geometry type with a list of fields and a spatial reference.
     final pointTable = FeatureCollectionTable(
-      fields: [
-        Field.text(name: 'Place', alias: 'Place Name', length: 50),
-      ],
+      fields: [Field.text(name: 'Place', alias: 'Place Name', length: 50)],
       geometryType: GeometryType.point,
       spatialReference: SpatialReference(wkid: 4326),
     );
 
+    // Set a simple renderer to style features from the table.
     pointTable.renderer = SimpleRenderer(
       symbol: SimpleMarkerSymbol(
         style: SimpleMarkerSymbolStyle.triangle,
@@ -86,75 +94,82 @@ class _AddFeatureCollectionLayerFromTableSampleState
       ),
     );
 
+    // Create a point.
+    final point = ArcGISPoint(
+      x: -79.497238,
+      y: 8.849289,
+      spatialReference: SpatialReference.wgs84,
+    );
+
+    // Create a feature with the point and add it to the table.
     final feature = pointTable.createFeature(
-      attributes: {
-        'Place': 'Current location',
-      },
-      geometry: ArcGISPoint(
-        x: -79.497238,
-        y: 8.849289,
-        spatialReference: SpatialReference.wgs84,
-      ),
+      attributes: {'Place': 'Current location'},
+      geometry: point,
     );
     pointTable.addFeature(feature);
 
-    _featureCollection.tables.add(pointTable);
+    return pointTable;
   }
 
-  void createPolylineTable() {
-    final linesTable = FeatureCollectionTable(
+  // Create a feature collection table using a polyline geometry.
+  FeatureCollectionTable createPolylineTable() {
+    // Create a feature collection table for the geometry type with a list of fields and a spatial reference.
+    final polylineTable = FeatureCollectionTable(
       fields: [
-        Field.text(name: 'Boundary', alias: 'Boundary Name', length: 50),
+        Field.text(name: 'Boundary', alias: 'Boundary Name', length: 50)
       ],
       geometryType: GeometryType.polyline,
       spatialReference: SpatialReference(wkid: 4326),
     );
 
-    linesTable.renderer = SimpleRenderer(
+    // Set a simple renderer to style features from the table.
+    polylineTable.renderer = SimpleRenderer(
       symbol: SimpleLineSymbol(
         style: SimpleLineSymbolStyle.dash,
         color: Colors.green,
         width: 3,
       ),
     );
 
-    final builder =
+    // Build a polyline.
+    final polylineBuilder =
         PolylineBuilder.fromSpatialReference(SpatialReference(wkid: 4326));
-    builder.addPoint(
+    polylineBuilder.addPoint(
       ArcGISPoint(
         x: -79.497238,
         y: 8.849289,
         spatialReference: SpatialReference.wgs84,
       ),
     );
-    builder.addPoint(
+    polylineBuilder.addPoint(
       ArcGISPoint(
         x: -80.035568,
         y: 9.432302,
         spatialReference: SpatialReference.wgs84,
       ),
     );
+    final polyline = polylineBuilder.toGeometry();
 
-    final feature = linesTable.createFeature(
-      attributes: {
-        'Boundary': 'AManAPlanACanalPanama',
-      },
-      geometry: builder.toGeometry(),
+    // Create a feature using the polyline and add it to the table.
+    final feature = polylineTable.createFeature(
+      attributes: {'Boundary': 'AManAPlanACanalPanama'},
+      geometry: polyline,
     );
-    linesTable.addFeature(feature);
+    polylineTable.addFeature(feature);
 
-    _featureCollection.tables.add(linesTable);
+    return polylineTable;
   }
 
-  void createPolygonTable() {
+  // Create a feature collection table using a polygon geometry.
+  FeatureCollectionTable createPolygonTable() {
+    // Create a feature collection table for the geometry type with a list of fields and a spatial reference.
     final polygonTable = FeatureCollectionTable(
-      fields: [
-        Field.text(name: 'Area', alias: 'Area Name', length: 50),
-      ],
+      fields: [Field.text(name: 'Area', alias: 'Area Name', length: 50)],
       geometryType: GeometryType.polygon,
       spatialReference: SpatialReference(wkid: 4326),
     );
 
+    // Set a simple renderer to style features from the table.
     polygonTable.renderer = SimpleRenderer(
       symbol: SimpleFillSymbol(
         style: SimpleFillSymbolStyle.diagonalCross,
@@ -167,38 +182,39 @@ class _AddFeatureCollectionLayerFromTableSampleState
       ),
     );
 
-    final builder =
+    // Build a polygon.
+    final polygonBuilder =
         PolygonBuilder.fromSpatialReference(SpatialReference(wkid: 4326));
-    builder.addPoint(
+    polygonBuilder.addPoint(
       ArcGISPoint(
         x: -79.497238,
         y: 8.849289,
         spatialReference: SpatialReference.wgs84,
       ),
     );
-    builder.addPoint(
+    polygonBuilder.addPoint(
       ArcGISPoint(
         x: -79.337936,
         y: 8.638903,
         spatialReference: SpatialReference.wgs84,
       ),
     );
-    builder.addPoint(
+    polygonBuilder.addPoint(
       ArcGISPoint(
         x: -79.11409,
         y: 8.895422,
         spatialReference: SpatialReference.wgs84,
       ),
     );
+    final polygon = polygonBuilder.toGeometry();
 
+    // Create a feature using the polygon and add it to the table.
     final feature = polygonTable.createFeature(
-      attributes: {
-        'Area': 'Restricted area',
-      },
-      geometry: builder.toGeometry(),
+      attributes: {'Area': 'Restricted area'},
+      geometry: polygon,
     );
     polygonTable.addFeature(feature);
 
-    _featureCollection.tables.add(polygonTable);
+    return polygonTable;
   }
 }
