Cut a geometry along a polyline.
Use case
You might cut a polygon representing a large parcel to subdivide it into smaller parcels.
How to use the sample
Tap on the "Cut" button to cut the polygon with the polyline and see the resulting parts (shaded in different colors).
Tap on the "Reset" button to restore the original state.
How it works
- Pass the geometry and polyline to
GeometryEngine.cutto cut the geometry along the polyline. - Loop through the returned list of part geometries. Some of these geometries may be multi-part.
Relevant API
- GeometryEngine.cut
- Polygon
- Polyline
Tags
cut, geometry, split
Sample Code
cut_geometry.dart
//
// Copyright 2024 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
//
// https://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.
//
import 'package:arcgis_maps/arcgis_maps.dart';
import 'package:flutter/material.dart';
import '../../utils/sample_state_support.dart';
class CutGeometry extends StatefulWidget {
const CutGeometry({super.key});
@override
State<CutGeometry> createState() => _CutGeometryState();
}
class _CutGeometryState extends State<CutGeometry> with SampleStateSupport {
// Create a controller for the map view.
final _mapViewController = ArcGISMapView.createController();
// A flag for when the map view is ready and controls can be used.
var _ready = false;
// A flag to track if the geometry has been cut.
var _geometryCut = false;
// The graphics for the original state of the sample.
late final Graphic _lakeGraphic;
late final Graphic _borderGraphic;
// Graphics overlay to present the graphics for the sample.
final _graphicsOverlay = GraphicsOverlay();
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
top: false,
child: Stack(
children: [
Column(
children: [
Expanded(
// Add a map view to the widget tree and set a controller.
child: ArcGISMapView(
controllerProvider: () => _mapViewController,
onMapViewReady: onMapViewReady,
),
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
// Button to trigger the cut function or reset to the original state.
ElevatedButton(
onPressed: _geometryCut ? resetGeometry : cutGeometry,
child: _geometryCut
? const Text('Reset')
: const Text('Cut'),
),
],
),
],
),
// Display a progress indicator and prevent interaction until state is ready.
Visibility(
visible: !_ready,
child: SizedBox.expand(
child: Container(
color: Colors.white30,
child: const Center(child: CircularProgressIndicator()),
),
),
),
],
),
),
);
}
void onMapViewReady() {
// Create a map with a topographic basemap style and add it to the map view controller.
final map = ArcGISMap.withBasemapStyle(BasemapStyle.arcGISTopographic);
_mapViewController.arcGISMap = map;
// Add the graphics overlay to the map view controller.
_mapViewController.graphicsOverlays.add(_graphicsOverlay);
// Initialize the graphics for the sample.
_initLakeGraphic();
_initBorderGraphic();
// Add the graphics to the graphics overlay.
_graphicsOverlay.graphics.addAll([_lakeGraphic, _borderGraphic]);
// Set the viewpoint to the lake graphic.
_mapViewController.setViewpoint(
Viewpoint.fromTargetExtent(_lakeGraphic.geometry!.extent),
);
// Set the ready state variable to true to enable the sample UI.
setState(() => _ready = true);
}
// Cut the lake geometry with the border geometry. The results
// of the cut will be displayed on the map.
void cutGeometry() {
// Cut the lake geometry with the border geometry.
final cutGeometries = GeometryEngine.cut(
geometry: _lakeGraphic.geometry!,
cutter: _borderGraphic.geometry! as Polyline,
);
// Create graphics for the cut geometries.
final canadianGraphic = Graphic(
geometry: cutGeometries.first,
symbol: SimpleFillSymbol(
style: SimpleFillSymbolStyle.backwardDiagonal,
color: Colors.green,
),
);
final usaGraphic = Graphic(
geometry: cutGeometries.last,
symbol: SimpleFillSymbol(
style: SimpleFillSymbolStyle.forwardDiagonal,
color: Colors.red,
),
);
// Add the graphics for the cut geometries to the graphics overlay.
_graphicsOverlay.graphics.addAll([canadianGraphic, usaGraphic]);
// Update the state to reflect the geometry cut.
setState(() => _geometryCut = true);
}
// Reset the graphics to the original state.
void resetGeometry() {
// Clear the graphics overlay and add the original graphics.
_graphicsOverlay.graphics.clear();
_graphicsOverlay.graphics.addAll([_lakeGraphic, _borderGraphic]);
// Update the state to reflect the geometry reset.
setState(() => _geometryCut = false);
}
// Utility function to build the Polygon geometry and create the Graphic for
// the lake. This geometry will be cut by the border geometry.
void _initLakeGraphic() {
// Build the Polygon for the lake.
final lakePolygonBuilder = PolygonBuilder(
spatialReference: _mapViewController.spatialReference,
);
lakePolygonBuilder.addPointXY(x: -10254374.668616, y: 5908345.076380);
lakePolygonBuilder.addPointXY(x: -10178382.525314, y: 5971402.386779);
lakePolygonBuilder.addPointXY(x: -10118558.923141, y: 6034459.697178);
lakePolygonBuilder.addPointXY(x: -9993252.729399, y: 6093474.872295);
lakePolygonBuilder.addPointXY(x: -9882498.222673, y: 6209888.368416);
lakePolygonBuilder.addPointXY(x: -9821057.766387, y: 6274562.532928);
lakePolygonBuilder.addPointXY(x: -9690092.583250, y: 6241417.023616);
lakePolygonBuilder.addPointXY(x: -9605207.742329, y: 6206654.660191);
lakePolygonBuilder.addPointXY(x: -9564786.389509, y: 6108834.986367);
lakePolygonBuilder.addPointXY(x: -9449989.747500, y: 6095091.726408);
lakePolygonBuilder.addPointXY(x: -9462116.153346, y: 6044160.821855);
lakePolygonBuilder.addPointXY(x: -9417652.665244, y: 5985145.646738);
lakePolygonBuilder.addPointXY(x: -9438671.768711, y: 5946341.148031);
lakePolygonBuilder.addPointXY(x: -9398250.415891, y: 5922088.336339);
lakePolygonBuilder.addPointXY(x: -9419269.519357, y: 5855797.317714);
lakePolygonBuilder.addPointXY(x: -9467775.142741, y: 5858222.598884);
lakePolygonBuilder.addPointXY(x: -9462924.580403, y: 5902686.086985);
lakePolygonBuilder.addPointXY(x: -9598740.325877, y: 5884092.264688);
lakePolygonBuilder.addPointXY(x: -9643203.813979, y: 5845287.765981);
lakePolygonBuilder.addPointXY(x: -9739406.633691, y: 5879241.702350);
lakePolygonBuilder.addPointXY(x: -9783061.694736, y: 5922896.763395);
lakePolygonBuilder.addPointXY(x: -9844502.151022, y: 5936640.023354);
lakePolygonBuilder.addPointXY(x: -9773360.570059, y: 6019099.583107);
lakePolygonBuilder.addPointXY(x: -9883306.649729, y: 5968977.105610);
lakePolygonBuilder.addPointXY(x: -9957681.938918, y: 5912387.211662);
lakePolygonBuilder.addPointXY(x: -10055501.612742, y: 5871965.858842);
lakePolygonBuilder.addPointXY(x: -10116942.069028, y: 5884092.264688);
lakePolygonBuilder.addPointXY(x: -10111283.079633, y: 5933406.315128);
lakePolygonBuilder.addPointXY(x: -10214761.742852, y: 5888134.399970);
// Generate the polygon graphic.
_lakeGraphic = Graphic(
geometry: lakePolygonBuilder.toGeometry(),
symbol: SimpleFillSymbol(
color: Colors.blue.withOpacity(0.5),
outline: SimpleLineSymbol(
color: Colors.blue,
width: 4.0,
style: SimpleLineSymbolStyle.solid,
),
),
);
}
// Utility funciton to build the Polyline geometry and create the Graphic for
// the border. This geometry will be used to cut the lake geometry.
void _initBorderGraphic() {
// Build the Polyline geometry for the border.
final borderPolylineBuilder = PolylineBuilder(
spatialReference: _mapViewController.spatialReference,
);
borderPolylineBuilder.addPointXY(x: -9981328.687124, y: 6111053.281447);
borderPolylineBuilder.addPointXY(x: -9946518.044066, y: 6102350.620682);
borderPolylineBuilder.addPointXY(x: -9872545.427566, y: 6152390.920079);
borderPolylineBuilder.addPointXY(x: -9838822.617103, y: 6157830.083057);
borderPolylineBuilder.addPointXY(x: -9446115.050097, y: 5927209.572793);
borderPolylineBuilder.addPointXY(x: -9430885.393759, y: 5876081.440801);
borderPolylineBuilder.addPointXY(x: -9415655.737420, y: 5860851.784463);
// Generate the polyline graphic.
_borderGraphic = Graphic(
geometry: borderPolylineBuilder.toGeometry(),
symbol: SimpleLineSymbol(
color: Colors.red,
width: 4.0,
style: SimpleLineSymbolStyle.dot,
),
);
}
}