ShapeSimplifierBase.Simplify(IEnumerable<MapItem>, Double) Method

Reduces the number of vertices that form the vector layer’s items.

Namespace: DevExpress.XtraMap

Assembly: DevExpress.XtraMap.v24.1.dll

NuGet Package: DevExpress.Win.Map

Declaration

C#

public void Simplify(
    IEnumerable<MapItem> items,
    double tolerance
)

VB.NET

Public Sub Simplify(
    items As IEnumerable(Of MapItem),
    tolerance As Double
)

Parameters

Name	Type	Description
items	IEnumerable<MapItem>	The map items to be simplified.
tolerance	Double	The percentage of vertices that vector shapes contain after simplification. This value is in the (0;100) range. The passed value is processed as 0 if it is less than 0 or not defined. The passed value is processed as 100 if greater than 100.

Remarks

The example below shows how to simplify items before they are displayed on a vector layer. To do this, call the Simplify method in a data adapter’s ItemsLoaded event handler.

C#

public Form1() {
    InitializeComponent();
    VectorItemsLayer mapLayer = (VectorItemsLayer)mapControl.Layers["MapLayer"];
    ShapefileDataAdapter adapter = new ShapefileDataAdapter() {
        FileUri = new Uri(new Uri(System.Reflection.Assembly.GetEntryAssembly().Location), filename)
    };
    adapter.ItemsLoaded += OnAdapterItemsLoaded;
    mapLayer.Data = adapter;
}
private void OnAdapterItemsLoaded(object sender, ItemsLoadedEventArgs e) {
    VisvalingamShapeSimplifier simplifier = new VisvalingamShapeSimplifier();
    simplifier.Simplify(items: e.Items, tolerance: 50);
}

VB.NET

Public Sub New()
    InitializeComponent()
    Dim mapLayer As VectorItemsLayer = CType(mapControl.Layers("MapLayer"), VectorItemsLayer)
    Dim adapter As ShapefileDataAdapter = New ShapefileDataAdapter() With {
        .FileUri = New Uri(New Uri(System.Reflection.Assembly.GetEntryAssembly().Location), filename)
    }
    adapter.ItemsLoaded += AddressOf OnAdapterItemsLoaded
    mapLayer.Data = adapter
End Sub

Private Sub OnAdapterItemsLoaded(ByVal sender As Object, ByVal e As ItemsLoadedEventArgs)
    Dim simplifier As VisvalingamShapeSimplifier = New VisvalingamShapeSimplifier()
    simplifier.Simplify(items:=e.Items, tolerance:=50)
End Sub

Alternatively, you can use the DouglasPeuckerShapeSimplifier algorithm instead of the VisvalingamShapeSimplifier.