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Best way to dynamically alter shape parameters in an InMemoryFeatureLayer

#1

I have an InMemoryFeatureLayer to store a series of EllipseShape objects.
I want to be able to dynamically alter the height and width of the EllipseShape objects.
I have tried to get each EllipseShape object from the InMemoryFeatureLayer in turn in order to use SetHeight and SetWidth as follows:

        EllipseShape range_ring = (EllipseShape)rx_ring_layer.InternalFeatures[rx_entry.Id.ToString()].GetShape();
        range_ring.SetHeightByUnit(radius, Map.MapUnit, DistanceUnit.Meter);
        range_ring.SetWidthByUnit(radius, Map.MapUnit, DistanceUnit.Meter);

Unfotunately, I get an InvalidCastException as the EllipseShape objects appear to have been stored as PolygonShape objects, despite them being created as follows:

            PointShape point = new PointShape(rx_entry.Longitude, rx_entry.Latitude);
            if (Map.MapUnit == GeographyUnit.Meter)
                point = (PointShape)proj4.ConvertToExternalProjection(point);
            rx_ring_layer.InternalFeatures.Add(rx_entry.Id.ToString(), new Feature(new EllipseShape(point, radius)));

Also, I have read the following in the help documentation for GetShape:

This method allows you to get a shape class from a Feature. Because the Feature stores the geometry for itself in well-known binary, it may take some time to generate a shape class if the geometry is complex.

It seems that the way I am going about this is all wrong. As I am new to Map Suite and GIS software in general, I was wondering if anyone could point me in the right direction?

#2

Hi Daniel,

After the EllipseShape is created on map, it exist as a polygon, so you cannot edit it.

The correct way is like this:

  1. Create a Feature based on your EllipseShape, and save the key parameters for example: centerPointFeature, horizontalRadius, verticalRadius.

  2. When you want to edit it, find the feature, read it’s original value, modify them and create a totally new EllipseShape.

  3. Remove old Feature with EllipseShape, and add the new Feature with EllipseShape.

Wish that’s helpful.

Regards,

Ethan

#3

Hi Ethan,

Many thanks for your response. What you describe is exactly how I’ve ended up doing it. It just seems slightly wasteful to create a new object rather than edit an existing one. Clearly, changing the radius of an ellipse will require it to be completely re-rendered, so I guess the time taken to do object deletion and re-creation is insignificant in comparison to the time taken to re-render.

Regards,

Dan.

#4

Hi Dan,

You can choose edit it or rebuild it, but I think the speed shouldn’t be feel when you use it exception you batch process lots of shapes.

Regards,

Ethan