= Feature Layers =
 * A 'Feature' is a Resource Record which has a Lat/Lon available.
 * ~~Features can be Points, Lines or Polygons~~
 * ~~Features can be exported in KML/GPX/etc~~
  * Need to update S3XRC for GPS symbol detection when !FeatureClass allocation changes
  * Need to update gis.get_marker() when !FeatureClass allocation changes
 * Features can be added to the Map
  * A Feature Layer is a query of Features
   * Resource
   * Filtered
    * Resource.Category (Report/Incident table, Missing Persons, L0->L3 in gis_location table)
   * Collection of Resources <- is this required?
    * New gis_landmark table can have Transport category for Port/Airport/Railway sub_categories
 * Features can be removed from the map or moved on the map interactively.
  * To do this via a single set of Controls means having a single Vector Layer (or having to manually select the active layer!).
   * Build up this Vector Layer from multiple Feature Layers
   * In order to be able to dynamically enable/disable individual Feature Groups whilst viewing the map, we need to write a custom layer switcher which refreshes the whole Features Layer client-side upon changes.
 * ~~User can define which layers should be selectable/enabled-by-default in the Situation Mapping layer switcher.~~
  * This list is personalisable.
   * move from layer definitions to gis_config
    * Have 1->M for Feature_Layers for available.
    * Attribute of visible stored in a separate multiple field.
     * Combine with special widget?

== Markers ==
The Marker used for the Features will be:
 * Cluster marker if multiple markers close together (styled in size & # for >2)
  * prevents performance issues as well as making things clearer
 * The Feature marker (if defined) <- is this required? (Will speed things up if removed)
  * Q: Should we provide an option to allow the Feature-Class icon to over-ride individual Feature Icons?
 * The Feature Class marker (if defined)
  * Styling based on values of an attribute of the resource
   * this is for display in specialist views only?
   * once we have core functionality, want UI to be able to choose the attribute, the values & the markers
 * The Default marker

[wiki:BluePrintGISMarkers Markers BluePrint]

== Popups ==
Clicking a Feature should bring up a Popup
 * This can be a URL to load (flexible, but slow) however, if not provided, the default is:
  * Loaded into the map during main load: no server-side calls
  * Header should be found from a set of common options (name/code)
  * All the list_fields with their labels
  * A link to open the record in a new tab
Clicking a Cluster should bring up a Popup
 * a list of the features within the cluster
  * each list item is hyperlinked to bring up the Feature's Popup (as well?)

Q: Provide option to add Labels to Features?
 * http://gis.ibbeck.de/ginfo/apps/OLExamples/OL26/examples/labels.html

== Implementation ==
=== Option A (preferred) ===
Hardcode the link between !FeatureClass & Resource (with optional category, e.g. for 'Report/Incident' table)
 * Add optional category_field/category_value columns to the feature_class table
 * If wanting feature-specific markers then add marker_id to resource tables (by bundling with location_id)
 * Replace feature_group table with feature_layer table
  * fields:
   * name
   * resource (used to populate the query field via an 'onvalidation')
   * filter_field (optional. used to populate the query field via an 'onvalidation')
   * filter_value (optional. used to populate the query field via an 'onvalidation')
   * query (hidden behind 'Advanced' button?)
   * comments
=== Option B ===
!FeatureClass is an attribute of the link table
 * location_id extended to include feature_class_id (& marker_id) fields
 * => a Feature Group cannot be a collection of Feature Classes since we can't trawl through all resources to see if any of them have been tagged for this FC

== Storage ==
[wiki:BluePrintGISStorage]

== Docs ==
 * http://docs.openlayers.org/library/overlays
 * http://dev.openlayers.org/docs/files/OpenLayers/Feature/Vector-js.html
 * http://dev.openlayers.org/docs/files/OpenLayers/Layer/Vector-js.html

=== Examples ===
 * Use HTTP to pull down Features List as XML: http://openlayers.org/dev/examples/behavior-fixed-http-gml.html
 * Controls to Add/Drag Features: http://openlayers.org/dev/examples/drag-feature.html
 * Select Feature (inc via Box): http://www.openlayers.org/dev/examples/select-feature.html
 * Popup on Feature: http://www.openlayers.org/dev/examples/select-feature-openpopup.html
 * Style Features:
  * http://www.openlayers.org/dev/examples/styles-context.html
  * http://www.openlayers.org/dev/examples/styles-unique.html
  * http://www.openlayers.org/dev/examples/sundials.html
 * Download/Upload serialized feature data: http://www.openlayers.org/dev/examples/vector-formats.html
 * Cluster Strategy: http://www.openlayers.org/dev/examples/strategy-cluster.html

=== Limitations ===
 * http://faq.openlayers.org/vector-related-questions/

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[wiki:BluePrintGeographicInformationSystems GIS BluePrints]