# Geometry engine simplify

Simplify a polygon with a self-intersecting geometry.

## 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

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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``````/*
*
* use this file except in compliance with the License. You may obtain a copy of
*
*
* Unless required by applicable law or agreed to in writing, software
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
*/

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.Button;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
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.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 line symbol
private final SimpleLineSymbol line = new SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.BLACK, 1);

@Override
public void start(Stage stage) {

try {
// create stack pane and application scene
StackPane stackPane = new StackPane();
Scene scene = new Scene(stackPane);

// 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);
Insets.EMPTY)));
controlsVBox.setMaxSize(110, 80);

// 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, Color.RED, line);

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

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

simplifyButton.setDisable(false);
} else {
}
});

// 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();

resultGeomOverlay = new GraphicsOverlay();

// create sample polygon
createPolygon();

// add the map view and control panel to stack pane
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());
Part partOne = new Part(partSegmentCollectionOne);

// part two
PointCollection partSegmentCollectionTwo = new PointCollection(SpatialReferences.getWebMercator());
Part partTwo = new Part(partSegmentCollectionTwo);

// part three
PointCollection partSegmentCollectionThree = new PointCollection(SpatialReferences.getWebMercator());
Part partThree = new Part(partSegmentCollectionThree);

PartCollection polygonParts = new PartCollection(partOne);

// transparent fill
SimpleFillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, Color.TRANSPARENT, 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);
}
}``````