Style DSL

[tobrun]

Now that we have concepts as Runtime Styling and Data Driven Styling due to support of expressions, layers, etc.
We can start thinking about introducing a builder like pattern to compose a style object.
Ideally this comes after but #757 but can be added independent.

For reference on how this looks in Kotlin code:

style(styleUri = Style.TRAFFIC_DAY) {
    +imageSource("imag") {
      url(IMAGE_URL)
      coordinates(
        listOf(
          listOf(-35.859375, 58.44773280389084),
          listOf(-16.171875, 58.44773280389084),
          listOf(-16.171875, 54.7246201949245),
          listOf(-35.859375, 54.7246201949245)
        )
      )
    }
    +geoJsonSource(id = "earthquakes") {
      url(GEOJSON_URL)
      cluster(false)
    }
    +circleLayer(layerId = "earthquakeCircle", sourceId = "earthquakes") {
      circleRadius(get { literal("mag") })
      circleColor(rgb(255.0, 0.0, 0.0))
      circleOpacity(0.3)
      circleStrokeColor(Color.WHITE)
    }
}

[felix-ht]

That would be great!

How it could look like in dart:

final style = Style(
  styleString: Styles.TRAFFIC_DAY,
  sources: [
    ImageSource(id: "imag", url: IMAGE_URL, coordinates: [
      [-35.859375, 58.44773280389084],
      [-16.171875, 58.44773280389084],
      [-16.171875, 54.7246201949245],
      [-35.859375, 54.7246201949245],
    ]),
    GeoJsonSource(id: "earthquakes", url: GEOJSON_URL, cluster: false),
  ],
  layers: [
    Layer(
      layerId: "earthquakeCircle",
      sourceId: "earthquakes",
      properties: CircleLayerProperties(
        circleRadius: [Expressions.get, "mag"],
        circleColor: "#ff0000",
        circleOpacity: 0.3,
        circleStrokeColor: Colors.white.toHexStringRGB(),
      ),
    ),
  ],
);

We could also add one common base class for layers and sources, but keeping them separate feels more "dartish" to me.

[stale]

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