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GeometryEngineBuffer Method (Geometry, Double)

Creates a buffer polygon at the specified distance around the given geometry. This is a planar buffer operation. Use BufferGeodetic(Geometry, Double, LinearUnit, Double, GeodeticCurveType) to produce geodetic buffers.

Namespace:  Esri.ArcGISRuntime.Geometry
Assembly:  Esri.ArcGISRuntime (in Esri.ArcGISRuntime.dll) Version: 100.9.0
Syntax
public static Geometry Buffer(
	Geometry geometry,
	double distance
)

Parameters

geometry
Type: Esri.ArcGISRuntime.GeometryGeometry
Specifies the input geometry.
distance
Type: SystemDouble
The distance in the unit of the geometry's spatial reference for which to buffer the geometry.

Return Value

Type: Geometry
The polygon that represents the buffered area.
Remarks

Planar measurements of distance and area can be extremely inaccurate if using an unsuitable spatial reference. Ensure that you understand the potential for error with the geometry's spatial reference. If you need to calculate more accurate results consider using a different spatial reference, or using the geodetic equivalent, BufferGeodetic(Geometry, Double, LinearUnit, Double, GeodeticCurveType). See https://developers.arcgis.com/documentation/core-concepts/spatial-references/ for more information about spatial references.

The polygon geometry that is generated from this Static Method is based upon the SpatialReference of the input geometry. A SpatialReference is a combination of an ellipsoid, datum, and a coordinate system used to display (aka. project) geographic data of the three dimensional Earth on a two dimensional surface (such as a piece of paper of computer monitor). A good article for describing how a spatial reference works can be found here. The important thing to know about creating buffers is that some SpatialReferences are better than others for getting accurate results. To get the most accurate buffer polygons using this method, consider using an 'area preserving' SpatialReference such as: Albers, Lambert, Mollweide, Hammer, Sinusoidal, and the like. If the input geometry to this method is not based on a good 'area preserving' SpatialReference, then there are two options available to produce accurate buffers: (1) use the Project(Geometry, SpatialReference) Static Method to project the geometry to a coordinate system that is better suited for buffers or (2) use the BufferGeodetic(Geometry, Double, LinearUnit, Double, GeodeticCurveType) Static Method which will use an internal projection algorithm to convert the geometry to a spherical coordinate system to obtain the most accurate buffers possible. See the Make measurements topic in the developers guide for more information.

Examples

WPF

Example Name: Buffer

Create a buffer around a map point and display the results as a `Graphic`

Code example screen shot.

C#
// 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.

using System.Windows;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using System.Drawing;

namespace ArcGISRuntime.WPF.Samples.Buffer
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Buffer",
        category: "Geometry",
        description: "Create a buffer around a map point and display the results as a `Graphic`",
        instructions: "1. Tap on the map.",
        tags: new[] { "analysis", "buffer", "euclidean", "geodesic", "geometry", "planar" })]
    public partial class Buffer
    {
        public Buffer()
        {
            InitializeComponent();

            // Initialize the map and graphics overlays.
            Initialize();
        }

        private void Initialize()
        {
            // Create a map with a topographic basemap and add it to the map view.
            MyMapView.Map = new Map(Basemap.CreateTopographic());

            // Handle the MapView's GeoViewTapped event to create buffers.
            MyMapView.GeoViewTapped += MyMapView_GeoViewTapped;

            // Create a fill symbol for geodesic buffer polygons.            
            Color geodesicBufferColor = Color.FromArgb(120, 255, 0, 0);
            SimpleLineSymbol geodesicOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, geodesicBufferColor, 2);
            SimpleFillSymbol geodesicBufferFillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, geodesicBufferColor, geodesicOutlineSymbol);

            // Create a fill symbol for planar buffer polygons.            
            Color planarBufferColor = Color.FromArgb(120, 0, 0, 255);
            SimpleLineSymbol planarOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, planarBufferColor, 2);
            SimpleFillSymbol planarBufferFillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, planarBufferColor, planarOutlineSymbol);

            // Create a marker symbol for tap locations.
            SimpleMarkerSymbol tapSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Cross, Color.White, 14);

            // Create a graphics overlay to display geodesic polygons, set its renderer and add it to the map view.
            GraphicsOverlay geodesicPolysOverlay = new GraphicsOverlay
            { 
                Id = "GeodesicPolys",
                Renderer = new SimpleRenderer(geodesicBufferFillSymbol)
            };
            MyMapView.GraphicsOverlays.Add(geodesicPolysOverlay);

            // Create a graphics overlay to display planar polygons, set its renderer and add it to the map view.
            GraphicsOverlay planarPolysOverlay = new GraphicsOverlay
            {
                Id = "PlanarPolys",
                Renderer = new SimpleRenderer(planarBufferFillSymbol)
            };
            MyMapView.GraphicsOverlays.Add(planarPolysOverlay);

            // Create a graphics overlay to display tap locations for buffers, set its renderer and add it to the map view.
            GraphicsOverlay tapLocationsOverlay = new GraphicsOverlay
            {
                Id = "TapPoints",
                Renderer = new SimpleRenderer(tapSymbol)
            };
            MyMapView.GraphicsOverlays.Add(tapLocationsOverlay);

            // Show the colors for each type of buffer in the UI.
            ShowBufferSwatches(planarBufferColor, geodesicBufferColor);
        }

        private void MyMapView_GeoViewTapped(object sender, Esri.ArcGISRuntime.UI.Controls.GeoViewInputEventArgs e)
        {
            try
            {
                // Get the location tapped by the user (a map point in the WebMercator projected coordinate system).
                MapPoint userTapPoint = e.Location;

                // Get the buffer distance (miles) entered in the text box.
                double bufferInMiles = System.Convert.ToDouble(BufferDistanceMilesTextBox.Text);

                // Call a helper method to convert the input distance to meters.
                double bufferInMeters = LinearUnits.Miles.ToMeters(bufferInMiles);

                // Create a planar buffer graphic around the input location at the specified distance.
                Geometry bufferGeometryPlanar = GeometryEngine.Buffer(userTapPoint, bufferInMeters);
                Graphic planarBufferGraphic = new Graphic(bufferGeometryPlanar);

                // Create a geodesic buffer graphic using the same location and distance.
                Geometry bufferGeometryGeodesic = GeometryEngine.BufferGeodetic(userTapPoint, bufferInMeters, LinearUnits.Meters, double.NaN, GeodeticCurveType.Geodesic);
                Graphic geodesicBufferGraphic = new Graphic(bufferGeometryGeodesic);

                // Create a graphic for the user tap location.
                Graphic locationGraphic = new Graphic(userTapPoint); 

                // Get the graphics overlays.
                GraphicsOverlay planarBufferGraphicsOverlay = MyMapView.GraphicsOverlays["PlanarPolys"];
                GraphicsOverlay geodesicBufferGraphicsOverlay = MyMapView.GraphicsOverlays["GeodesicPolys"];
                GraphicsOverlay tapPointGraphicsOverlay = MyMapView.GraphicsOverlays["TapPoints"];

                // Add the buffer polygons and tap location graphics to the appropriate graphic overlays.
                planarBufferGraphicsOverlay.Graphics.Add(planarBufferGraphic);
                geodesicBufferGraphicsOverlay.Graphics.Add(geodesicBufferGraphic);
                tapPointGraphicsOverlay.Graphics.Add(locationGraphic);
            }
            catch (System.Exception ex)
            {
                // Display an error message if there is a problem generating the buffers.
                MessageBox.Show(ex.Message, "Error creating buffers");
            }
        }

        private void ShowBufferSwatches(Color planarBufferColor, Color geodesicBufferColor)
        {
            // Create an equivalent System.Windows.Media.Color for each of the buffer symbol colors (System.Drawing.Color).
            System.Windows.Media.Color planarLabelColor = System.Windows.Media.Color.FromArgb(
                planarBufferColor.A,
                planarBufferColor.R,
                planarBufferColor.G,
                planarBufferColor.B);
            System.Windows.Media.Color geodesicLabelColor = System.Windows.Media.Color.FromArgb(
                geodesicBufferColor.A,
                geodesicBufferColor.R,
                geodesicBufferColor.G,
                geodesicBufferColor.B);

            // Show buffer symbol colors in the UI by setting the appropriate Ellipse object fill color.
            BufferSwatchPlanarEllipse.Fill = new System.Windows.Media.SolidColorBrush(planarLabelColor);
            BufferSwatchGeodesicEllipse.Fill = new System.Windows.Media.SolidColorBrush(geodesicLabelColor);
        }

        private void ClearBuffersButton_Click(object sender, RoutedEventArgs e)
        {
            // Clear the buffer and point graphics.
            foreach (GraphicsOverlay ov in MyMapView.GraphicsOverlays)
            {
                ov.Graphics.Clear();
            }
        }
    }
}
XAML
<UserControl x:Class="ArcGISRuntime.WPF.Samples.Buffer.Buffer"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:esri="http://schemas.esri.com/arcgis/runtime/2013">
    <Grid>
        <esri:MapView x:Name="MyMapView" />
        <Border Style="{StaticResource BorderStyle}">
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition />
                    <ColumnDefinition Width="Auto" />
                </Grid.ColumnDefinitions>
                <Label Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="3"
                       HorizontalContentAlignment="Center"
                       FontWeight="SemiBold"
                       Content="Click the map to create planar and geodesic buffers." />
                <Label Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2"
                       HorizontalAlignment="Right"
                       Content="Buffer distance (miles):" />
                <TextBox x:Name="BufferDistanceMilesTextBox"
                         Grid.Row="1" Grid.Column="2"
                         TextAlignment="Right" VerticalContentAlignment="Center"
                         MinWidth="80"
                         Text="1000" />
                <Ellipse x:Name="BufferSwatchPlanarEllipse"
                         Grid.Row="2" Grid.Column="0"
                         Stroke="LightGray"
                         Width="20" Height="20" />
                <Label Grid.Row="2" Grid.Column="1"
                       HorizontalAlignment="Left"
                       Content="Planar buffers (Web Mercator)" />
                <Ellipse x:Name="BufferSwatchGeodesicEllipse"
                         Grid.Row="3" Grid.Column="0"
                         Stroke="LightGray"
                         Width="20" Height="20" />
                <Label Grid.Row="3" Grid.Column="1"
                       HorizontalAlignment="Left"
                       Content="Geodesic buffers" />
                <Button x:Name="ClearBuffersButton"
                        Grid.Row="4" Grid.Column="0" Grid.ColumnSpan="3"
                        Margin="0,10,0,0"
                        Content="Clear"
                        Click="ClearBuffersButton_Click" />
            </Grid>
        </Border>
    </Grid>
</UserControl>
See Also
Additional Examples
Hyperlink to ExampleDescription
BufferCreate a buffer around a map point and display the results as a `Graphic`