Brian,
We didn’t expose GridFeatureSource because GridIsoLineLayer is not a FeatureLayer, it inherits from IsoLineLayer which directly from the Layer. If exposing this GridFeatureSource maybe most of users will think it is a FeatureLayer and try to use some FeatureLayer methods which it doesn’t have.
Key observation for the missing of StreamLoading event in GridIsoLineLayer. We’ve just added it to the latest daily build (5.5.131.0), please download and have another try.
“Input data must be more detailized to build isolines.” Is an internal exception, It’s thrown if miscellaneous errors occurs when building the IsoLines from the grid cell matrix. We have update the exception description to “Grid Cell Matrix not correct for building IsoLines” and if you are having this issue, could you please send a sample and your data to us so we can dig into it?
Thanks,
Ben