Cut geometry

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Sample viewer app

Cut a geometry along a polyline.

Image of cut geometry

Use case

You might cut a polygon representing a large parcel to subdivide it into smaller parcels.

How to use the sample

Tap the button to cut the polygon with the polyline and see the resulting parts (shaded in different colors).

How it works

  1. Pass the geometry and polyline to class AGSGeometryEngine.cut(_:withCutter:) to cut the geometry along the polyline.
  2. Loop through the returned list of part geometries. Some of these geometries may be multi-part.

Relevant API

  • AGSPolygon
  • AGSPolyline
  • class AGSGeometryEngine.cut(_:withCutter:)

Tags

cut, geometry, split

Sample Code

CutGeometryViewController.swift
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// Copyright 2018 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.

import UIKit
import ArcGIS

class CutGeometryViewController: UIViewController {
    // MARK: Storyboard views

    /// The map view managed by the view controller.
    @IBOutlet var mapView: AGSMapView! {
        didSet {
            // Create a map with a topographic basemap.
            mapView.map = AGSMap(basemapStyle: .arcGISTopographic)
            // Add the graphics overlays to the map view.
            mapView.graphicsOverlays.addObjects(from: [lakeGraphicsOverlay, cutGraphicsOverlay])
            // Set viewpoint to the extent of the Lake Superior graphics overlay.
            mapView.setViewpointGeometry(lakeSuperiorPolygonGraphic.geometry!)
        }
    }

    // MARK: Instance properties

    /// A Boolean value indicating whether the geometry is cut.
    var isGeometryCut = false

    /// A polygon representing the area of Lake Superior.
    var lakeSuperiorPolygonGraphic: AGSGraphic {
        lakeGraphicsOverlay.graphics.firstObject as! AGSGraphic
    }

    /// A polyline representing the Canada/USA border.
    var borderPolylineGraphic: AGSGraphic {
        lakeGraphicsOverlay.graphics.lastObject as! AGSGraphic
    }

    /// A graphics overlay containing the Lake Superior polygon and border line.
    let lakeGraphicsOverlay: AGSGraphicsOverlay = {
        let lakeSuperiorPolygonGraphic: AGSGraphic = {
            // Create an array of points that represents Lake Superior (polygon).
            // Use the same spatial reference as the underlying base map.
            let points = [
                AGSPoint(x: -10254374.668616, y: 5908345.076380, spatialReference: .webMercator()),
                AGSPoint(x: -10178382.525314, y: 5971402.386779, spatialReference: .webMercator()),
                AGSPoint(x: -10118558.923141, y: 6034459.697178, spatialReference: .webMercator()),
                AGSPoint(x: -9993252.729399, y: 6093474.872295, spatialReference: .webMercator()),
                AGSPoint(x: -9882498.222673, y: 6209888.368416, spatialReference: .webMercator()),
                AGSPoint(x: -9821057.766387, y: 6274562.532928, spatialReference: .webMercator()),
                AGSPoint(x: -9690092.583250, y: 6241417.023616, spatialReference: .webMercator()),
                AGSPoint(x: -9605207.742329, y: 6206654.660191, spatialReference: .webMercator()),
                AGSPoint(x: -9564786.389509, y: 6108834.986367, spatialReference: .webMercator()),
                AGSPoint(x: -9449989.747500, y: 6095091.726408, spatialReference: .webMercator()),
                AGSPoint(x: -9462116.153346, y: 6044160.821855, spatialReference: .webMercator()),
                AGSPoint(x: -9417652.665244, y: 5985145.646738, spatialReference: .webMercator()),
                AGSPoint(x: -9438671.768711, y: 5946341.148031, spatialReference: .webMercator()),
                AGSPoint(x: -9398250.415891, y: 5922088.336339, spatialReference: .webMercator()),
                AGSPoint(x: -9419269.519357, y: 5855797.317714, spatialReference: .webMercator()),
                AGSPoint(x: -9467775.142741, y: 5858222.598884, spatialReference: .webMercator()),
                AGSPoint(x: -9462924.580403, y: 5902686.086985, spatialReference: .webMercator()),
                AGSPoint(x: -9598740.325877, y: 5884092.264688, spatialReference: .webMercator()),
                AGSPoint(x: -9643203.813979, y: 5845287.765981, spatialReference: .webMercator()),
                AGSPoint(x: -9739406.633691, y: 5879241.702350, spatialReference: .webMercator()),
                AGSPoint(x: -9783061.694736, y: 5922896.763395, spatialReference: .webMercator()),
                AGSPoint(x: -9844502.151022, y: 5936640.023354, spatialReference: .webMercator()),
                AGSPoint(x: -9773360.570059, y: 6019099.583107, spatialReference: .webMercator()),
                AGSPoint(x: -9883306.649729, y: 5968977.105610, spatialReference: .webMercator()),
                AGSPoint(x: -9957681.938918, y: 5912387.211662, spatialReference: .webMercator()),
                AGSPoint(x: -10055501.612742, y: 5871965.858842, spatialReference: .webMercator()),
                AGSPoint(x: -10116942.069028, y: 5884092.264688, spatialReference: .webMercator()),
                AGSPoint(x: -10111283.079633, y: 5933406.315128, spatialReference: .webMercator()),
                AGSPoint(x: -10214761.742852, y: 5888134.399970, spatialReference: .webMercator()),
                AGSPoint(x: -10254374.668616, y: 5901877.659929, spatialReference: .webMercator())
            ]

            // Create a polygon from the array of points.
            let polygon = AGSPolygon(points: points)

            // Create a blue border line symbol with a stroke weight of 4 for
            // the Lake Superior polygon.
            let lineSymbol = AGSSimpleLineSymbol(style: .solid, color: .blue, width: 4)

            // Create a semi transparent blue fill symbol using the red
            // border line symbol for the Lake Superior polygon.
            let fillSymbol = AGSSimpleFillSymbol(style: .solid, color: #colorLiteral(red: 0, green: 0, blue: 1, alpha: 0.1), outline: lineSymbol)

            // Create and return a graphic using the polyline and fill symbol
            // for the border polyline.
            return AGSGraphic(geometry: polygon, symbol: fillSymbol)
        }()

        let borderPolylineGraphic: AGSGraphic = {
            // Create an array of points that represents a cut line.
            let points = [
                AGSPoint(x: -9981328.687124, y: 6111053.281447, spatialReference: .webMercator()),
                AGSPoint(x: -9946518.044066, y: 6102350.620682, spatialReference: .webMercator()),
                AGSPoint(x: -9872545.427566, y: 6152390.920079, spatialReference: .webMercator()),
                AGSPoint(x: -9838822.617103, y: 6157830.083057, spatialReference: .webMercator()),
                AGSPoint(x: -9446115.050097, y: 5927209.572793, spatialReference: .webMercator()),
                AGSPoint(x: -9430885.393759, y: 5876081.440801, spatialReference: .webMercator()),
                AGSPoint(x: -9415655.737420, y: 5860851.784463, spatialReference: .webMercator())
            ]

            // Create a polyline from the array of points.
            let polyline = AGSPolyline(points: points)

            // Create a red border line symbol with a stroke weight of 5.
            let lineSymbol = AGSSimpleLineSymbol(style: .dot, color: .red, width: 5)

            // Create and return a graphic using the polyline and line symbol
            // for the border polyline.
            return AGSGraphic(geometry: polyline, symbol: lineSymbol, attributes: nil)
        }()

        // Create a graphics overlay.
        let overlay = AGSGraphicsOverlay()
        // Add the Lake Superior graphics to the overlay.
        overlay.graphics.addObjects(from: [lakeSuperiorPolygonGraphic, borderPolylineGraphic])
        return overlay
    }()

    /// The graphics overlay containing cut graphics.
    let cutGraphicsOverlay = AGSGraphicsOverlay()

    // MARK: Actions

    /// Cut geometry and add resulting graphics.
    func cutGeometry() {
        // Cut the Lake Superior polygon using the border polyline.
        guard let parts = AGSGeometryEngine.cut(lakeSuperiorPolygonGraphic.geometry!, withCutter: borderPolylineGraphic.geometry as! AGSPolyline),
              parts.count == 2,
              let firstPart = parts.first,
              let secondPart = parts.last else {
            return
        }
        // Create the graphics for the Canadian and USA sides of Lake Superior.
        let canadaSideGraphic = AGSGraphic(geometry: firstPart, symbol: AGSSimpleFillSymbol(style: .backwardDiagonal, color: .green, outline: nil))
        let usaSideGraphic = AGSGraphic(geometry: secondPart, symbol: AGSSimpleFillSymbol(style: .forwardDiagonal, color: .yellow, outline: nil))
        // Add the graphics to the graphics overlay.
        cutGraphicsOverlay.graphics.addObjects(from: [canadaSideGraphic, usaSideGraphic])
    }

    /// Removes all cut graphics.
    func reset() {
        cutGraphicsOverlay.graphics.removeAllObjects()
    }

    @IBAction func cutGeometryWithPolyline(_ sender: UIBarButtonItem) {
        isGeometryCut ? reset() : cutGeometry()
        isGeometryCut.toggle()
        // Set button title based on whether the geometry is cut.
        sender.title = isGeometryCut ? "Reset" : "Cut"
    }

    // MARK: UIViewController

    override func viewDidLoad() {
        super.viewDidLoad()
        // Add the source code button item to the right of navigation bar.
        (navigationItem.rightBarButtonItem as! SourceCodeBarButtonItem).filenames = ["CutGeometryViewController"]
    }
}

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