Legend

What it does

The legend lists the layers drawn on the map, in draw order. There is a swatch for each layer.

It is not the catalog. The catalog offers layers you could add; the legend shows the layers on the map.

Each row has a visibility toggle, an opacity slider, Zoom to layer, About this layer, Layer style, and Remove layer. At the top of the list are actions for all layers: Show all layers, Hide all layers, Clear all layers, Save layers…, and Permalink.

The swatch comes from the layer's paint specification. A fill layer shows its fill, a line layer its stroke, and a classified layer its ramp. Layers without readable paint, such as raster basemaps or remote styles, can use a small data: image from the config.

The list reads top to bottom as the map reads front to back. Dragging a row reorders the map, not just the list.

Using it

1. Open the legend from the toolbar. Every layer on the map is listed, topmost first.
2. Use the checkbox to hide a layer without removing it. Hidden layers keep their place in the order and their style.
3. Drag a row by its handle to move a layer in front of or behind another.
4. Open a row's menu for what applies to that layer alone: zoom to its extent, read its description, restyle it, or take it off the map.

The style panel is not modal. It floats over the map and can be dragged by its title bar, so you can see the map while changing colors.

Zoom to layer uses the layer's own extent where it declares one, and the extent of its features where it does not. This works for a local vector layer without any configuration.

In your own map

Add layerOverview to a toolbar. The legend lists whatever layers the map has and needs no knowledge of the layers themselves.

Three attributes rename its headings, for a map in another language or with another idea of what a basemap is called: overview-title, background-title and background-group-label.

Extending it

The legend reads store.mapLayers, the map's record of what is drawn. Key order is the stacking order from bottom to top, and the list shows it reversed. Dragging calls adapter.moveLayer(layerId, beforeLayerId).

Two implementation details matter when changing it:

• Cesium cannot reorder a vector layer against a raster one. Imagery is baked into the globe's surface texture and primitives always draw over it. Within one kind, reordering works. This is a property of the engine, not a gap in the adapter.
• A swatch belongs to the layer, not to the panel. metadata.swatch on a layer definition overrides everything the panel could derive, and every panel that lists layers reads the same value. Only self-contained values are honored. A remote URL is ignored, because the value goes straight into a style attribute.