add a start to take labels expressions from esri.

[PieterVanPoyer]

Hi,

I've made a starting point for adding labels to the esri-leaflet-renderers. I see this is requested by: https://github.com/ynunokawa/L.esri.WebMap/issues/74 . I wanted this feature also for my own project.

There is more work to be done in this area. For example only center and topright position is supported now. The expression language is far more complicated than currently implemented.

This is a breaking change. Some users did probably work arround the missing label feature themself. So a major version bump is required in my opinion.

Kind regards, Pieter

[jgravois]

related: https://github.com/Esri/esri-leaflet/issues/916

[PieterVanPoyer]

very cool! thanks for sharing what you've come up with so far.

Nice!

I've marked this PR as Work In Progress. What should I do to finish this pull request?

Some things I am thinking of:

• Provide an implementation for the other esri label positions (now only top right, and a default to center is provided. [ http://help.arcgis.com/en/sdk/10.0/java_ao_adf/api/arcobjects/com/esri/arcgis/carto/esriServerPointLabelPlacementType.html ]
• Optimize the check of the zoomlevels range.
• Write some tests?
• Provide an example where you can see it work.

What do you think?

[jgravois]

I don't work at @Esri anymore but that sounds like a good plan to me.

if no one swoops in to help you land your work here, you could always publish it on your own.