topic How to add a new polygon to a new layer? in ArcObjects SDK Questions

How to add a new polygon to a new layer?

KevinChan — Thu, 30 Sep 2010 19:57:57 GMT

hi guys,

I am about to start a project using ArcEngine 10. I'm just playing around with samples and snippets provided right now.

One of the things i'm trying to achieve is to let the user draw polygons on the map and add the polygon to an existing/newly created layer.

I followed this snippet

     ///<summary>Draws a polygon on the screen in the ActiveView where the mouse is clicked.</summary>
        ///
        ///<param name="activeView">An IActiveView interface</param>
        /// 
        ///<remarks>Ideally, this function would be called from within the OnMouseDown event that was created with the ArcGIS base tool template.</remarks>
        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();
        }

I tried looking for classes that inherits from ILayer interface. However, I can't seem to find a class that allows me to CREATE a new layer and ADD an IGeometry object into it.

I guess I also want to be able to choose a Feature layer and add polygons into them. Is there a way I can programmatically create the feature layer and add a polygon to it? or do I have to choose the layer first then try to add the polygon to it?

Any help would be much appreciated.

Thanks and Regards,
Kev

Re: How to add a new polygon to a new layer?

SteveFang — Wed, 27 Oct 2010 23:23:37 GMT

So are you trying to take the graphic drawn on screen and turn it into a real GIS polygon feature? If so, try looking at iFeatureworkspace.createfeatureclass to create a featureclass to hold you GIS features. IFeatureclass has a createfeature method which you can use to create the new polygon and just set the shape for the polygon to the geometry of the graphic. I am just giving you the abbreviated version but you can probably find sample code on the EDN site. Good luck.

Re: How to add a new polygon to a new layer?

guomu — Thu, 28 Oct 2010 02:33:00 GMT

So are you trying to take the graphic drawn on screen and turn it into a real GIS polygon feature? If so, try looking at iFeatureworkspace.createfeatureclass to create a featureclass to hold you GIS features. IFeatureclass has a createfeature method which you can use to create the new polygon and just set the shape for the polygon to the geometry of the graphic. I am just giving you the abbreviated version but you can probably find sample code on the EDN site. Good luck.

agree this!:) looking at iFeatureworkspace.createfeatureclass is important.