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How to draw a polygon on the screen (ArcObjects .NET 10.4 SDK)

How to draw a polygon on the screen


Summary
This topic shows how to draw a polygon using IRubberBand.

Drawing a polygon on the screen

The following code draws a polygon on the screen in the map where the mouse is clicked. The x,y coordinates come from a mousedown click event when the user interacts with the application. In this example, the polygon is not persisted on the screen but is removed after the next screen refresh.
[VB.NET]
Public Sub DrawPolygon(ByVal activeView As ESRI.ArcGIS.Carto.IActiveView)
    
    If activeView Is Nothing Then
        Return
    End If
    
    Dim screenDisplay As ESRI.ArcGIS.Display.IScreenDisplay=activeView.ScreenDisplay
    
    ' Constant.
    screenDisplay.StartDrawing(screenDisplay.hDC, CShort(ESRI.ArcGIS.Display.esriScreenCache.esriNoScreenCache))
    Dim rgbColor As ESRI.ArcGIS.Display.IRgbColor=New ESRI.ArcGIS.Display.RgbColorClass
    rgbColor.Red=255
    
    Dim color As ESRI.ArcGIS.Display.IColor=rgbColor ' Implicit cast.
    Dim simpleFillSymbol As ESRI.ArcGIS.Display.ISimpleFillSymbol=New ESRI.ArcGIS.Display.SimpleFillSymbolClass
    simpleFillSymbol.Color=color
    
    Dim symbol As ESRI.ArcGIS.Display.ISymbol=TryCast(simpleFillSymbol, ESRI.ArcGIS.Display.ISymbol) ' Dynamic cast.
    Dim rubberBand As ESRI.ArcGIS.Display.IRubberBand=New ESRI.ArcGIS.Display.RubberPolygonClass
    Dim geometry As ESRI.ArcGIS.Geometry.IGeometry=rubberBand.TrackNew(screenDisplay, symbol)
    screenDisplay.SetSymbol(symbol)
    screenDisplay.DrawPolygon(geometry)
    screenDisplay.FinishDrawing()
    
End Sub
[C#]
public void DrawPolygon(ESRI.ArcGIS.Carto.IActiveView activeView)
{

    if (activeView == null)
    {
        return ;
    }

    ESRI.ArcGIS.Display.IScreenDisplay screenDisplay=activeView.ScreenDisplay;

    // Constant.
    screenDisplay.StartDrawing(screenDisplay.hDC, (System.Int16)
        ESRI.ArcGIS.Display.esriScreenCache.esriNoScreenCache); // Explicit cast.
    ESRI.ArcGIS.Display.IRgbColor rgbColor=new ESRI.ArcGIS.Display.RgbColorClass();
    rgbColor.Red=255;

    ESRI.ArcGIS.Display.IColor color=rgbColor; // Implicit cast.
    ESRI.ArcGIS.Display.ISimpleFillSymbol simpleFillSymbol=new
        ESRI.ArcGIS.Display.SimpleFillSymbolClass();
    simpleFillSymbol.Color=color;

    ESRI.ArcGIS.Display.ISymbol symbol=simpleFillSymbol as
        ESRI.ArcGIS.Display.ISymbol; // Dynamic cast.
    ESRI.ArcGIS.Display.IRubberBand rubberBand=new
        ESRI.ArcGIS.Display.RubberPolygonClass();
    ESRI.ArcGIS.Geometry.IGeometry geometry=rubberBand.TrackNew(screenDisplay,
        symbol);
    screenDisplay.SetSymbol(symbol);
    screenDisplay.DrawPolygon(geometry);
    screenDisplay.FinishDrawing();
}


See Also:

How to draw a point on the screen
How to draw a polyline on the screen
How to draw a rectangle on the screen




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