@polar/plugin-layer-chooser

LayerChooser

The tool offers layer selection to the user.

Scope

The LayerChooser offers an additive (usually Overlays, technically named with type: 'mask') and an exclusive (usually background maps, type: 'background') selection of layers to the users.

Order of layers within a layer is currently always as initially configured.

Configuration

The tool does not require any configuration for itself, but is based on the mapConfiguration.layers array. It will infer its options from there, and change layer visibility and availability depending on minZoom and maxZoom.

Each object in mapConfiguration.layers array fits this definition:

fieldName	type	description
id	string	Service register id.
visibility	boolean	Initial visibility.
type	enum["background", "mask"]	Layer handling. Backgrounds are mutually exclusive, masks ("overlays") can be stacked.
name	string	Display name in UI.
minZoom	?number	If set, layer only available (and selectable) from this zoom level on.
maxZoom	?number	If set, layer only available (and selectable) to this zoom level.
options	options	Shows a layer-specific sub-menu; its contents are configurable.

mapConfiguration.layers.options

An option wheel will appear in the layer chooser that allows opening a sub-menu with configured configuration options for the end user.

fieldName	type	description
layers	Boolean | layers	If truthy, all configured layers of the layer for can be turned off and on by the user. ⚠️ Only implemented for WMS. Only implemented for top layers; that is, only first level of nesting is considered.

mapConfiguration.layers.options.layers

This field is named like this to match the OGC specification for their name; that is, layers have layers that may have layers that may have layers, and so on. However, only the first level (a layer's layers) is currently implemented.

fieldName	type	description
order	?string	Optional. If not given, field layers from service description will be used, and defines order of options. If layer defined in service description's layers and order, it's initially on. If only in order, it's initially off. If only in layers, it's always-on. If in neither, it's always-off.
title	Boolean | Record<name, layerName>	Title to be displayed for sub-layer. If false, layer name itself will be used as given in service description 'layers' field. If true, it is assumed a name exists in the layer's GetCapabilities, and that will be used. If Record, it maps the layer name to an arbitrary display name given by the configuration. The layerName can be any string.
legend	Boolean | Record<name, legendUrl>	Legend image to be used for sub-layer. If false, no image is displayed. If true, it is assumed an image exists in the layer's GetCapabilities, and that will be used. If Record, it maps the layer name to a linked image. The legendUrl can be any valid reachable image URL.