ShapefileDataAdapter Class

A data adapter that loads data from shapefiles and displays it on vector layers.

Namespace: DevExpress.XtraMap

Assembly: DevExpress.XtraMap.v20.1.dll

Declaration

public class ShapefileDataAdapter :
    FileDataAdapterBase,
    ISupportBoundingRectAdapter
Public Class ShapefileDataAdapter
    Inherits FileDataAdapterBase
    Implements ISupportBoundingRectAdapter

Remarks

The shapefile format is a geospatial vector data format that uses geometric shapes (points, polylines, and polygons) to display geographic data (rivers, lakes, countries, etc.). The Map Control uses data from two types of files:

  • The .shp file, which contains geometry data.
  • The .dbf file, which contains data associated with geometric shapes (e.g., names and GDP values for countries).

The Map Control stores data from the .dbf file as attributes for each vector item. You can colorize shapes based on attribute values or display attribute data in shape tooltips.

The image below shows a vector map loaded from a shapefile with the applied ChoroplethColorizer.

Map Control with data from a shape file

The following table lists supported shapefile elements and related map items:

Shape File Element

Map Item

Point,
PointM (the M value is ignored),
PointZ (the Z value is ignored),
Multipoint,
MultipointM (the M value is ignored),
MultipointZ (the Z value is ignored).

MapDot

PolyLine,
PolylineM (the M value is ignored),
PolylineZ (the Z value is ignored).

MapPolyline

Polygon,
PolygonM (the M value is ignored),
PolygonZ (the Z value is ignored).

MapPolygon

For more information about shapefile element types, refer to the following ESRI document: ESRI Shapefile Technical Description.

Load Data

To load data from a shapefile, follow the steps below:

public partial class Form1 : Form {
  const string filename = "../../Data/Countries.shp";
  VectorItemsLayer MapLayer { get { return (VectorItemsLayer)mapControl1.Layers["MapLayer"]; } }

  public Form1() {
      InitializeComponent();
      MapLayer.Data = CreateData();
  }
  private MapDataAdapterBase CreateData() {
      Uri baseUri = new Uri(System.Reflection.Assembly.GetEntryAssembly().Location);
      // Create an adapter to load data from the shapefile.
      ShapefileDataAdapter adapter = new ShapefileDataAdapter() {
          FileUri = new Uri(baseUri, filename)
      };
      return adapter;
  }
}

Access and Customize Map Items

When vector items are loaded, the FileDataAdapterBase.ItemsLoaded event occurs. Use the e.Items property to access map items.

private void Form1_Load(object sender, EventArgs e) {
    Uri baseUri = new Uri(System.Reflection.Assembly.GetExecutingAssembly().Location);
    ShapefileDataAdapter adapter = new ShapefileDataAdapter();
    adapter.FileUri = new Uri(baseUri, "../../Data/Countries.shp");
    adapter.ItemsLoaded += Adapter_ItemsLoaded;
    mapControl1.Layers.Add(new VectorItemsLayer {
        Data = adapter
    });
}

private void Adapter_ItemsLoaded(object sender, ItemsLoadedEventArgs e) {
    foreach (MapItem item in e.Items) {
        item.Fill = System.Drawing.Color.Gray;
    }
}

Use the MapControl.ZoomToFitLayerItems method to zoom the map to fit layer items.

private void Form1_Load(object sender, EventArgs e) {
  Uri baseUri = new Uri(System.Reflection.Assembly.GetExecutingAssembly().Location);
  ShapefileDataAdapter adapter = new ShapefileDataAdapter();
  adapter.FileUri = new Uri(baseUri, "../../Data/Countries.shp");
  VectorItemsLayer layer = new VectorItemsLayer();
  layer.Data = adapter;
  layer.DataLoaded += Layer_DataLoaded;
  mapControl1.Layers.Add(layer);
}

private void Layer_DataLoaded(object sender, DataLoadedEventArgs e) {
  mapControl1.ZoomToFitLayerItems();
}

You can change shape colors based on shape data. Refer to the following help topic for more information: Colorizers.

You can also group items of the same type. To do this, initialize the MapDataAdapterBase.Clusterer property with a clusterer that aggregates map items based on their location.

Implements

Inheritance

See Also