How to identify objects in dynamic display

Identifying objects in dynamic display

1. At draw time, add a watermark that will be used to identify the object. Use the OpenGL glLoadName() method. If you need additional unique identifiers, use it with glPushName()/glPopName(). If you need a single unique identifier, use IDynamicDisplay2.SelectionIdentifier. For example, if you're using it as part of an AfterDynamicDraw event implementation (and not as part of a layer implementation).
   
   The following code example shows how to add the object identifier (OID) as an OpenGL watermark to implement a hit test:

uint ID=Convert.ToUInt32(r[0]);
OpenGL.GL.glLoadName(ID);

2. Convert the identified point into window coordinates. Use the IDynamicDisplay2.Locate method to locate the available elements. To provide the best performance, if the elements are part of a given layer, use the layer's indication enum to instruct dynamic display to apply the selection query to the specified layer only. Calling the Locate method results in an array populated with the IDynamicHit array indicating the hit elements. Each dynamicHit will have unique IDs set by the call to glLoadName(). See the following code example:

IEnvelope inEnv;
if (pGeom.GeometryType == esriGeometryType.esriGeometryEnvelope)
    inEnv=pGeom.Envelope;
else
    inEnv=pGeom as IEnvelope;
IArea area=inEnv as IArea;
if (area == null)
    return null;
int x, y;
m_displayTransformation.FromMapPoint(area.Centroid, out x, out y);
IArray dynamicHitArray=m_dynamicDisplay.Locate(x, y,
    esriDynamicSelectionMode.esriDSMLayers, this as IDynamicLayer);
if (dynamicHitArray == null)
    return null;

int count=dynamicHitArray.Count;
if (count == 0)
    return null;
IArray identifyObjArray=new ArrayClass();
IPropertySet propSet=null;
IIdentifyObj idObj=null;
IIdentifyObject idObject=null;
IDynamicHit dynamicHit=null;
for (int i=0; i < count; ++i)
{
    dynamicHit=dynamicHitArray.get_Element(i)as IDynamicHit;
    if (dynamicHit == null)
        continue;
    // Get the record.
    DataRow r=m_table.Rows[dynamicHit.ObjectID];
    if (r == null)
        continue;
    // Instantiate a new Identify object.
    idObj=new MyDynamicLayerIdentifyObj();
    if (idObj.CanIdentify(this as ILayer))
    {
        // Populate a property set with the item's info.
        propSet=new PropertySetClass();
        propSet.SetProperty("OID", r[0]);
        propSet.SetProperty("X", r[1]);
        propSet.SetProperty("Y", r[2]);
        propSet.SetProperty("STEPX", r[3]);
        propSet.SetProperty("STEPY", r[4]);
        propSet.SetProperty("HEADING", r[5]);
        propSet.SetProperty("TYPE", r[6]);
        // Add the item to the outgoing array.
        idObject=idObj as IIdentifyObject;
        idObject.PropertySet=propSet;
        identifyObjArray.Add(idObj);
    }

string ESRI.ArcGIS.Carto.IIdentifyObj.Name
{
    get
    {
        string oid=String.Empty;
        if (m_propset != null)
        {
            oid=Convert.ToString(m_propset.GetProperty("OID"));
        }
        return "DynamidDataInfo_" + oid;
    }
}

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