AnimationDeveloperSamples.MapGraphicKeyframe.MoveElement C# (CSharp) Method

        private void MoveElement(IElement elem, IPoint new_pos, IAGAnimationContainer pContainer)
        {
            ITransform2D transform2D = elem as ITransform2D;
            IPoint origin;

            if (elem.Geometry.GeometryType == esriGeometryType.esriGeometryPoint)
            {
                origin = elem.Geometry as IPoint;
            }
            else
            {
                IEnvelope elementEnvelope = elem.Geometry.Envelope;
                IArea elementArea = elementEnvelope as IArea;
                origin = elementArea.Centroid;
            }

            AddPropertySet(elem);

            IElementProperties prop = (IElementProperties)elem; //record the old properties
            IPropertySet propSet;
            propSet = (IPropertySet)prop.CustomProperty;
            IEnvelope oldEnv = GetElementBound(elem, pContainer);
            propSet.SetProperty("Envelope", oldEnv);

            transform2D.Move(new_pos.X - origin.X, new_pos.Y - origin.Y);
        }