@antv/l7-map

Map

Map fork from [email protected], keep event loop, responds user interaction and updates the internal state of the map (current viewport, camera angle, etc.)

sequenceDiagram
    actor user
    participant DOM
    participant handler_manager
    participant handler
    participant camera
    participant transform
    participant map

    user->>camera: map#setCenter, map#panTo
    camera->>transform: update
    camera->>map: fire move event
    map->>map: _render()

    user->>DOM: resize, pan,<br>click, scroll,<br>...
    DOM->>handler_manager: DOM events
    handler_manager->>handler: forward event
    handler-->>handler_manager: HandlerResult
    handler_manager->>transform: update
    handler_manager->>map: fire move event
    map->>map: _render()

• Transform holds the current viewport details (pitch, zoom, bearing, bounds, etc.). Two places in the code update transform directly:
  • Camera (parent class of Map) in response to explicit calls to Camera#panTo, Camera#setCenter
  • HandlerManager in response to DOM events. It forwards those events to interaction processors that live in src/ui/handler, which accumulate a merged HandlerResult that kick off a render frame loop, decreasing the inertia and nudging map.transform by that amount on each frame from HandlerManager#_updateMapTransform(). That loop continues in the inertia decreases to 0.
• Both camera and handler_manager are responsible for firing move, zoom, movestart, moveend, ... events on the map after they update transform. Each of these events (along with style changes and data load events) triggers a call to Map#_render() which renders a single frame of the map.