Enhancement: Zoom to layer extent

[slibby]

When adding a layer, if the user is currently viewing an area outside the extent of the layer (rectangle A does not intersect rectangle B), the screen should pan to the area of data coverage and display the service extent as a rectangle on the map (kind of like how HOT handles this)

[mapmeld]

I looked at https://github.com/proj4js/proj4js for more info on how to convert a layer extent from a different projection. The City of Madison, Wisconsin provides wkid 103412 as their projection.

https://maps.cityofmadison.com/arcgis/rest/services/Public/OPEN_DATA_TRANS/MapServer/18/metadata?f=json

I don't see a way to implement this without finding a large set of defaults, a service to retrieve projection definitions, or allow user to write in the projection details

[slibby]

You should be able to use a Geometry service to do the reprojection with only the input SpatialReference from the MapServer or FeatureServer layer, i.e. http://sampleserver6.arcgisonline.com/arcgis/rest/services/Utilities/Geometry/GeometryServer/project?inSR=4326&outSR=102100&geometries=%7B%22geometryType%22%3A%22esriGeometryPolygon%22%2C%22geometries%22%3A%5B%7B%22rings%22%3A%5B%5B%5B-117%2C34%5D%2C%5B-116%2C34%5D%2C%5B-117%2C33%5D%2C%5B-117%2C34%5D%5D%2C%5B%5B-115%2C44%5D%2C%5B-114%2C43%5D%2C%5B-115%2C43%5D%2C%5B-115%2C44%5D%5D%5D%7D%2C%7B%22rings%22%3A%5B%5B%5B32%2C17%5D%2C%5B31%2C17%5D%2C%5B30%2C17%5D%2C%5B30%2C16%5D%2C%5B32%2C17%5D%5D%5D%7D%5D%7D&transformation=&transformForward=false&f=html

[slibby]

@mapmeld I think this should happen after the layer list is loaded (/0 to /x) and the user selects a layer, but before they see the list of attributes (which often obscures the entire map). In most cases, I believe that the map should zoom to that extent to start, unless the user is at a smaller current map extent (more zoomed in) than that extent would move them to.

[jgravois]

10.3+ and ArcGIS Online query operations support returnExtentOnly to fetch the bounding box of an arbitrary selection (or the entire layer) in any projection.

// 20171003134925
// https://services.arcgis.com/rOo16HdIMeOBI4Mb/arcgis/rest/services/Heritage_Trees_Portland/FeatureServer/0/query?returnGeometry=true&where=1%3D1&outSr=4326&outFields=*&returnExtentOnly=true&f=json

{
  "extent": {
    "xmin": -122.74906513128271,
    "ymin": 45.435197255383585,
    "xmax": -122.50384940834815,
    "ymax": 45.593128938067593,
    "spatialReference": {
      "wkid": 4326,
      "latestWkid": 4326
    }
  }
}

as such, i think it'd be just fine to only offer a 'zoom to layer' feature for modern services.

[mapmeld]

I do get the extent returned with the initial metadata, I just can't control what projection comes back. I am thinking that this feature is possible to add and then only keep enabled for services with a common spatial reference

Something else to keep in mind: zoom to extent will be useful but unlikely to be perfect - a citywide service shouldn't be imported in one go like this, we expect people to zoom in. But it does help with initial setup / figuring out why things aren't working

[slibby]

Another option would be to have some means of "minimizing" the attribute-picker page so that you can see the map behind it, right now once you add a service URL, you can no longer zoom to a different area to reduce the number of features in the current extent without closing the attribute display.