What it is

mmgisAPI is the contract MMGIS offers to anything outside its own bundle: a host page, an iframe parent, or a plugin tool. It lives in a single file — src/essence/mmgisAPI/mmgisAPI.js — and is intentionally narrow. Where the inner core (L_, Map_, ToolController_) is sprawling and imperative, mmgisAPI is the curated surface that callers are allowed to depend on.

There is no IPC layer. The whole API is plain JavaScript, attached to window.mmgisAPI once the app boots. Iframe embedders reach in through iframe.contentWindow.mmgisAPI — see examples/ReactWrappedIframe/index.html, which does exactly that and then calls mmgisAPI.getVisibleLayers() and mmgisAPI.toggleLayer(name) from the outer React app. There is no postMessage protocol; the same-origin (or FRAME_ANCESTORS-permitted) handshake is direct.

How it gets wired up

The file exports two objects: mmgisAPI_ (internal, mutable) and mmgisAPI (the JSDoc'd public surface). Core boot calls mmgisAPI_.fina(Map_) once the Leaflet map is ready, which assigns mmgisAPI.map and fires the embedder's onLoaded callback. From that point on, window.mmgisAPI is live.

mmgisAPI.onLoaded(() => {
  mmgisAPI.toggleLayer('Terrain', true)
  mmgisAPI.addEventListener('onClick', (e) => console.log(e.latlng))
})

Categories of capability

The methods cluster into a handful of areas:

• Layers. addLayer, removeLayer, toggleLayer, getLayers, getLayerConfigs, getVisibleLayers, plus dynamic-data helpers clearVectorLayer, updateVectorLayer, appendLineString, and trim/keep variants for streaming feature data.
• Selection and viewport. selectFeature, getActiveFeature, featuresContained (everything in the current bounds), writeCoordinateURL, project/unproject against the configured CRS.
• Time. A pass-through to TimeControl_: setTime, setLayerTime, getTime, reloadTimeLayers, setLayersTimeStatus.
• Tools. getActiveTool, getActiveTools, overwriteLegends (lets an embedder render its own legend UI but keep MMGIS's logic).
• Events. addEventListener / removeEventListener translate a small vocabulary — onPan, onZoom, onClick, toolChange, layerVisibilityChange, newActiveFeature, etc. — to either Leaflet map events or DOM CustomEvents. The mapping is deliberately small so the embed contract stays cheap to maintain.
• Direct Leaflet escape hatch. mmgisAPI.map is the live Leaflet map. Anything not covered above can be done with raw Leaflet calls; the inline comment on addLayer says as much: "For a more 'temporary' layer, use Leaflet directly through mmgisAPI.map".

The plugin bus

A second, newer surface lives in the same file: a mitt-based pub/sub plus a request/response registry. This is what tools and plugins use to talk to each other and to the core without import-coupling.

• on(event, cb) / off / emit(event, data) — fire-and-forget events.
• provide(name, handler) / request(name, data) — async data fetch by string key.
• forPlugin(pluginId) — returns a scoped { emit, provide } that auto-prefixes names with plugin:<id>:. ToolController_ calls this for every loaded tool, so each tool gets tool.api populated automatically.

Core modules register handlers under stable namespaces during boot. Map_ provides map:getCenter, map:getBounds, map:setView, map:fitBounds. Layers_ provides layers:getAll, layers:getVisible, layers:toggle. TimeControl provides time:getCurrent, time:set. They also emit events like feature:active, tool:change, and layer:visibilityChange as state moves. A plugin can listen for those without importing any internal module.

Where to look

When building an iframe embed, start from examples/WrappedIframe/ (static) or examples/ReactWrappedIframe/ (React, shows the contentWindow.mmgisAPI handoff). When authoring a plugin tool, read the forPlugin block at the bottom of mmgisAPI.js and the registration sites in Map_.js, Layers_.js, and ToolController_.js to see which event/request names are already in use.