GIS Module

We use ​OpenLayers to display Maps with some ​GeoExt widgets.

Guidelines for Developers wishing to make use of Mapping within their Module

The easiest approach is to call the Mapping API.

Controller

map = gis.show_map()
return dict(map=map)

View

{{=XML(map)}}

Examples

Check the following functions in controllers/gis.py:

• map_viewing_client()
• display_feature()
• display_features()

Full API description

Best to get live from the source:

• ​https://github.com/flavour/eden/blob/master/modules/s3/s3gis.py#L6014

Variable Markers

Example:

query = (db.gis_location.deleted == False)
query = query & (db.gis_location.id == db["%s_%s" % (module, resource)].location_id)
locations = db(query).select(db.gis_location.id, db.gis_location.uuid, db.gis_location.name, db.gis_location.wkt, db.gis_location.lat, db.gis_location.lon)
for i in range(0, len(locations)):
    locations[i].gis_location.shape = "circle"
    locations[i].gis_location.size = locations[i][db["%s_%s" % (module, resource)].MyIntegerField]

Guidelines for Developers wishing to extend the functionality of the core GIS

OpenLayers

The GIS module uses OpenLayers for Display purposes, so a thorough understanding of this is a great foundation for what we do:

• ​http://trac.openlayers.org/wiki/Documentation#BeforeGettingStarted--TheTechnologiesBehindOpenLayers
• ​http://trac.openlayers.org/wiki/NewToOpenLayers

Projections: ​http://trac.openlayers.org/wiki/Documentation/Dev/proj4js

Debugging advice: ​http://docs.openlayers.org/help/minimize.html

GUI

The map window is wrapped in an Ext GUI based on ​GeoExt (formerly ​MapFish client)

How to debug WMS

• ​WMS Inspector - Firefox add-on

How to add a new Layer type

Assuming that OpenLayers supports the layertype:

Model

modules/s3db/gis.py

_gis_layer_types = ["newlayertype", "..."]
table = self.define_table("gis_layer_newlayertype",
                          name_field(),
                          Field("description", label=T("Description")),
                          Field("enabled", "boolean", default=True, label=T("Available in Viewer?")),
                          Field("visible", "boolean", default=True,
                                label=T("On by default? (only applicable to Overlays)")),
                          Field("url", label=T("Location"), requires = IS_NOT_EMPTY(),
                                comment=DIV(_class="tooltip",
                                            _title="%s|%s" % (T("Location"),
                                                              T("The URL to access the service.")))),
                          Field("version", length=32,
                                label=T("Version"), default="1.1.1",
                                requires=IS_IN_SET(["1.1.1", "1.3.0"], zero=None)),
                          Field("base", "boolean", default=False,
                                label=T("Base Layer?")),
                          Field("transparent", "boolean", default=True,
                                label=T("Transparent?")),
                          gis_opacity(),
                          role_required(),       # Single Role
                          #roles_permitted(),    # Multiple Roles (needs implementing in modules/s3gis.py)
                          *s3_timestamp())

Controller

controllers/gis.py

def layer_newlayertype():
    """ RESTful CRUD controller """
    if settings.get_security_map() and not s3_has_role("MapAdmin"):
        unauthorised()

    resourcename = request.function
    tablename = "%s_%s" % (module, resourcename)
    table = s3db[tablename]

    # Model options
    table.url.comment = SPAN("*", _class="req")

    # CRUD Strings
    type = "New Layer Type"
    LAYERS = T(TYPE_LAYERS_FMT % type)
    ADD_NEW_LAYER = T(ADD_NEW_TYPE_LAYER_FMT % type)
    EDIT_LAYER = T(EDIT_TYPE_LAYER_FMT % type)
    LIST_LAYERS = T(LIST_TYPE_LAYERS_FMT % type)
    NO_LAYERS = T(NO_TYPE_LAYERS_FMT % type)
    s3.crud_strings[tablename] = Storage(
        title_create=ADD_LAYER,
        title_display=LAYER_DETAILS,
        title_list=LAYERS,
        title_update=EDIT_LAYER,
        title_search=SEARCH_LAYERS,
        subtitle_create=ADD_NEW_LAYER,
        subtitle_list=LIST_LAYERS,
        label_list_button=LIST_LAYERS,
        label_create_button=ADD_LAYER,
        label_delete_button = DELETE_LAYER,
        msg_record_created=LAYER_ADDED,
        msg_record_modified=LAYER_UPDATED,
        msg_record_deleted=LAYER_DELETED,
        msg_list_empty=NO_LAYERS)

    # Post-processor
    def postp(r, output):
        s3_action_buttons(r)
        return output
    response.s3.postp = postp

    output = s3_rest_controller()

    if not "gis" in response.view:
        response.view = "gis/" + response.view

    return output

View

views/gis/map_service_catalogue.html

<li><a href='{{=URL(f="layer_newlayertype")}}'>New Layer Type</a> - Description</li>

Module

Classes need adding: modules/s3gis.py

class NewTypeLayer(Layer):
...

def show_map():
for LayerType in [
                  ...
                  NewTypeLayer,

Static

OpenLayers code needs adding: static/scripts/S3/s3.gis.layers.js

function addNewTyppeLayer(layer) {
    ...
}
function addLayers() {
    ....
    if (S3.gis.layers_newlayertype) {
        for (i = 0; i < S3.gis.layers_newlayertype.length; i++) {
            addNewTypeLayer(S3.gis.layers_newlayertype[i]);
        }
    }
    ....
}

cd static/scripts/tools
build gis

See Also

• BluePrint/GIS
• UserGuidelines/GIS
• DeveloperGuidelines/GIS/InAction

DeveloperGuidelines