Geometry engine simplify

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Sample viewer app

Simplify a polygon with a self-intersecting geometry.

Image of geometry engine simplify

Use case

A user may draw a polygon which is self-intersecting or contains incorrect ring orientations. The geometry must be simplified before it can be saved to a geodatabase.

How to use the sample

Click the 'Simplify' button to simplify the geometry. Click 'Reset' to reset to the original geometry.

How it works

  1. Check if the polygon geometry needs to be simplified using GeometryEngine.isSimple(Geometry).
  2. Simplify the polygon's geometry using GeometryEngine.simplify(Geometry).

Relevant API

  • Geometry
  • GeometryEngine

Additional information

The concept of topological simplicity is different than geometry generalization, where points are removed from polygons or lines to create a more generalized result while preserving overall shape. See the 'Densify and Generalize' sample for comparison.

Tags

geometry, polygon, simplify, spatial operations, topology

Sample Code

GeometryEngineSimplifySample.java
                                                                                                                                                                                                                                       
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/*
 * Copyright 2017 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.
 */

package com.esri.samples.geometry_engine_simplify;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Paint;
import javafx.stage.Stage;

import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.geometry.Geometry;
import com.esri.arcgisruntime.geometry.GeometryEngine;
import com.esri.arcgisruntime.geometry.Part;
import com.esri.arcgisruntime.geometry.PartCollection;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.geometry.PointCollection;
import com.esri.arcgisruntime.geometry.Polygon;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.loadable.LoadStatus;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.BasemapStyle;
import com.esri.arcgisruntime.mapping.view.Graphic;
import com.esri.arcgisruntime.mapping.view.GraphicsOverlay;
import com.esri.arcgisruntime.mapping.view.MapView;
import com.esri.arcgisruntime.symbology.SimpleFillSymbol;
import com.esri.arcgisruntime.symbology.SimpleLineSymbol;

public class GeometryEngineSimplifySample extends Application {

  private ArcGISMap map; // keep loadable in scope to avoid garbage collection
  private GraphicsOverlay resultGeomOverlay;
  private Graphic polygon;
  private MapView mapView;

  // simple black (0xFF000000) line symbol
  private final SimpleLineSymbol line = new SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, 0xFF000000, 1);

  @Override
  public void start(Stage stage) {

    try {
      // create stack pane and application scene
      StackPane stackPane = new StackPane();
      Scene scene = new Scene(stackPane);
      scene.getStylesheets().add(getClass().getResource("/geometry_engine_simplify/style.css").toExternalForm());

      // set title, size, and add scene to stage
      stage.setTitle("Geometry Engine Simplify Sample");
      stage.setWidth(800);
      stage.setHeight(700);
      stage.setScene(scene);
      stage.show();

      // authentication with an API key or named user is required to access basemaps and other location services
      String yourAPIKey = System.getProperty("apiKey");
      ArcGISRuntimeEnvironment.setApiKey(yourAPIKey);

      // create a control panel
      VBox controlsVBox = new VBox(6);
      controlsVBox.setBackground(new Background(new BackgroundFill(Paint.valueOf("rgba(0,0,0,0.3)"), CornerRadii.EMPTY,
          Insets.EMPTY)));
      controlsVBox.setPadding(new Insets(10.0));
      controlsVBox.setMaxSize(110, 80);
      controlsVBox.getStyleClass().add("panel-region");

      // create simplify button
      Button simplifyButton = new Button("Simplify");
      simplifyButton.setMaxWidth(Double.MAX_VALUE);
      simplifyButton.setDisable(true);

      // create reset button
      Button resetButton = new Button("Reset");
      resetButton.setMaxWidth(Double.MAX_VALUE);
      resetButton.setDisable(true);

      // perform the simplify geometry operation
      simplifyButton.setOnAction(e -> {

        // check if the geometry needs to be simplified
        if (!GeometryEngine.isSimple(polygon.getGeometry())) {

          // simplify the geometry
          Geometry resultPolygon = GeometryEngine.simplify(polygon.getGeometry());

          // update result as a red graphic
          SimpleFillSymbol redSymbol = new SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, 0xFFE91F1F, line);
          resultGeomOverlay.getGraphics().add(new Graphic(resultPolygon, redSymbol));

          resetButton.setDisable(false);
          simplifyButton.setDisable(true);
        }
      });

      // clear result layer
      resetButton.setOnAction(e -> {
        resultGeomOverlay.getGraphics().clear();
        simplifyButton.setDisable(false);
        resetButton.setDisable(true);
      });

      // add buttons to the control panel
      controlsVBox.getChildren().addAll(simplifyButton, resetButton);

      // create a map with the light gray basemap style
      map = new ArcGISMap(BasemapStyle.ARCGIS_LIGHT_GRAY);

      // enable geometry operations when the map is done loading
      map.addDoneLoadingListener(() -> {
        if (map.getLoadStatus() == LoadStatus.LOADED) {
          simplifyButton.setDisable(false);
        } else {
          Alert alert = new Alert(Alert.AlertType.ERROR, "Map Failed to Load!");
          alert.show();
        }
      });

      // create a map view and set the map to it
      mapView = new MapView();
      mapView.setMap(map);

      // set a viewpoint on the map view, centered on London
      mapView.setViewpointCenterAsync(new Point(-13500, 6710327, SpatialReferences.getWebMercator()), 25000);

      // create geometry layers
      GraphicsOverlay geomOverlay = new GraphicsOverlay();
      mapView.getGraphicsOverlays().add(geomOverlay);

      resultGeomOverlay = new GraphicsOverlay();
      mapView.getGraphicsOverlays().add(resultGeomOverlay);

      // create sample polygon
      createPolygon();
      geomOverlay.getGraphics().add(polygon);

      // add the map view and control panel to stack pane
      stackPane.getChildren().addAll(mapView, controlsVBox);
      StackPane.setAlignment(controlsVBox, Pos.TOP_LEFT);
      StackPane.setMargin(controlsVBox, new Insets(10, 0, 0, 10));

    } catch (Exception e) {
      // on any error, display the stack trace
      e.printStackTrace();
    }
  }

  /**
   * Creates the polygon.
   */
  private void createPolygon() {

    // part one
    PointCollection partSegmentCollectionOne = new PointCollection(SpatialReferences.getWebMercator());
    partSegmentCollectionOne.add(new Point(-13020, 6710130));
    partSegmentCollectionOne.add(new Point(-14160, 6710130));
    partSegmentCollectionOne.add(new Point(-14160, 6709300));
    partSegmentCollectionOne.add(new Point(-13020, 6709300));
    partSegmentCollectionOne.add(new Point(-13020, 6710130));
    Part partOne = new Part(partSegmentCollectionOne);

    // part two
    PointCollection partSegmentCollectionTwo = new PointCollection(SpatialReferences.getWebMercator());
    partSegmentCollectionTwo.add(new Point(-12160, 6710730));
    partSegmentCollectionTwo.add(new Point(-13160, 6710730));
    partSegmentCollectionTwo.add(new Point(-13160, 6709100));
    partSegmentCollectionTwo.add(new Point(-12160, 6709100));
    partSegmentCollectionTwo.add(new Point(-12160, 6710730));
    Part partTwo = new Part(partSegmentCollectionTwo);

    // part three
    PointCollection partSegmentCollectionThree = new PointCollection(SpatialReferences.getWebMercator());
    partSegmentCollectionThree.add(new Point(-12560, 6710030));
    partSegmentCollectionThree.add(new Point(-13520, 6710030));
    partSegmentCollectionThree.add(new Point(-13520, 6709000));
    partSegmentCollectionThree.add(new Point(-12560, 6709000));
    partSegmentCollectionThree.add(new Point(-12560, 6710030));
    Part partThree = new Part(partSegmentCollectionThree);

    PartCollection polygonParts = new PartCollection(partOne);
    polygonParts.add(partTwo);
    polygonParts.add(partThree);

    // transparent (0x00000000) fill
    SimpleFillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, 0x00000000, line);
    polygon = new Graphic(new Polygon(polygonParts), fillSymbol);

  }

  /**
   * Stops and releases all resources used in application.
   */
  @Override
  public void stop() {

    if (mapView != null) {
      mapView.dispose();
    }
  }

  /**
   * Opens and runs application.
   *
   * @param args arguments passed to this application
   */
  public static void main(String[] args) {

    Application.launch(args);
  }
}

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