Add data and rendering definition

app/src/tiles/dataDefinition.ts

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+import { strictParseInt } from "../parse";
+import { DataConfig } from "./renderers/datasourceRenderer";
+
+const BUILDING_LAYER_DEFINITIONS = {
+    base_light: `(
+        SELECT
+            b.location_number as location_number,
+            g.geometry_geom
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+    ) as outline`,
+    base_night: `(
+        SELECT
+            b.location_number as location_number,
+            g.geometry_geom
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+    ) as outline`,
+    date_year: `(
+        SELECT
+            b.date_year as date_year,
+            g.geometry_geom
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+    ) as outline`,
+    size_storeys: `(
+        SELECT
+            (
+                coalesce(b.size_storeys_attic, 0) +
+                coalesce(b.size_storeys_core, 0)
+            ) as size_storeys,
+            g.geometry_geom
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+    ) as outline`,
+    location: `(
+        SELECT
+            (
+                case when b.location_name is null then 0 else 1 end +
+                case when b.location_number is null then 0 else 1 end +
+                case when b.location_street is null then 0 else 1 end +
+                case when b.location_line_two is null then 0 else 1 end +
+                case when b.location_town is null then 0 else 1 end +
+                case when b.location_postcode is null then 0 else 1 end +
+                case when b.location_latitude is null then 0 else 1 end +
+                case when b.location_longitude is null then 0 else 1 end +
+                case when b.ref_toid is null then 0 else 1 end +
+                case when b.ref_osm_id is null then 0 else 1 end
+            ) as location_info_count,
+            g.geometry_geom
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+    ) as location`,
+    likes: `(
+        SELECT
+            g.geometry_geom,
+            b.likes_total as likes
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+            AND b.likes_total > 0
+    ) as location`,
+    conservation_area: `(
+        SELECT
+            g.geometry_geom
+        FROM
+            geometries as g,
+            buildings as b
+        WHERE
+            g.geometry_id = b.geometry_id
+            AND b.planning_in_conservation_area = true
+    ) as conservation_area`
+};
+
+const GEOMETRY_FIELD = 'geometry_geom';
+
+function getBuildingsDataConfig(tileset: string, dataParams: any): DataConfig {
+    const table = BUILDING_LAYER_DEFINITIONS[tileset];
+
+    if(table == undefined) {
+        throw new Error('Invalid tileset requested');
+    }
+
+    return {
+        geometry_field: GEOMETRY_FIELD,
+        table: table
+    };
+}
+
+function getHighlightDataConfig(tileset: string, dataParams: any): DataConfig {
+    let { highlight, base } = dataParams;
+
+    highlight = strictParseInt(highlight);
+
+    if(isNaN(highlight) || base == undefined || base.match(/^\w+$/) == undefined) {
+        throw new Error('Bad parameters for highlight layer');
+    }
+
+    return {
+        geometry_field: GEOMETRY_FIELD,
+        table: `(
+            SELECT
+                g.geometry_geom,
+                '${base}' as base_layer
+            FROM
+                geometries as g
+            WHERE
+                g.geometry_id = ${highlight}
+        ) as highlight`
+    };
+}
+
+export {
+    getBuildingsDataConfig,
+    getHighlightDataConfig
+};

app/src/tiles/rendererDefinition.ts

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+import { TileCache } from "./tileCache";
+import { BoundingBox, TileParams } from "./types";
+import { StitchRenderer } from "./renderers/stitchRenderer";
+import { CachedRenderer } from "./renderers/cachedRenderer";
+import { BranchingRenderer } from "./renderers/branchingRenderer";
+import { WindowedRenderer } from "./renderers/windowedRenderer";
+import { BlankRenderer } from "./renderers/blankRenderer";
+import { DatasourceRenderer } from "./renderers/datasourceRenderer";
+import { getBuildingsDataConfig, getHighlightDataConfig } from "./dataDefinition";
+
+const buildingDataRenderer = new DatasourceRenderer(getBuildingsDataConfig);
+
+const stitchRenderer = new StitchRenderer(undefined); // depends recurrently on cache, so parameter will be set later
+
+/**
+ * Zoom level when we switch from rendering direct from database to instead composing tiles
+ * from the zoom level below - gets similar effect, with much lower load on Postgres
+ */
+const STITCH_THRESHOLD = 12;
+
+const renderOrStitchRenderer = new BranchingRenderer(
+    ({ z }) => z <= STITCH_THRESHOLD,
+    stitchRenderer, // refer to the prepared stitch renderer
+    buildingDataRenderer
+);
+
+const tileCache = new TileCache(
+    process.env.TILECACHE_PATH,
+    {
+        tilesets: ['date_year', 'size_storeys', 'location', 'likes', 'conservation_area'],
+        minZoom: 9,
+        maxZoom: 18,
+        scales: [1, 2]
+    },
+    ({ tileset, z }: TileParams) => (tileset === 'date_year' && z <= 16) ||
+        ((tileset === 'base_light' || tileset === 'base_night') && z <= 17) ||
+        z <= 13
+);
+
+const cachedRenderer = new CachedRenderer(
+    tileCache,
+    renderOrStitchRenderer
+);
+
+// set up stitch renderer to use the data renderer with caching
+stitchRenderer.tileRenderer = cachedRenderer;
+
+const highlightRenderer = new DatasourceRenderer(getHighlightDataConfig);
+
+const highlightOrBuildingRenderer = new BranchingRenderer(
+    ({ tileset }) => tileset === 'highlight',
+    highlightRenderer,
+    cachedRenderer
+);
+
+const blankRenderer = new BlankRenderer();
+
+/**
+ * Hard-code extent so we can short-circuit rendering and return empty/transparent tiles outside the area of interest
+ * bbox in CRS epsg:3857 in form: [w, s, e, n]
+ */
+const EXTENT_BBOX: BoundingBox = [-61149.622628, 6667754.851372, 28128.826409, 6744803.375884];
+const mainRenderer = new WindowedRenderer(
+    EXTENT_BBOX,
+    highlightOrBuildingRenderer,
+    blankRenderer
+);
+
+export {
+    mainRenderer,
+    tileCache
+};