PMTiles/js/adapters.ts

// biome-ignore lint: needed for Leaflet + IIFE to work
declare const L: any;
// biome-ignore lint: needed for window.URL to disambiguate from cloudflare workers
declare const window: any;
declare const document: DocumentLike;

import type { Coords } from "leaflet";
import { PMTiles, TileType } from "./index";

interface DocumentLike {
  // biome-ignore lint: we don't want to bring in the entire document type
  createElement: (s: string) => any;
}

// biome-ignore lint: we don't want to bring in the entire document type
type DoneCallback = (error?: Error, tile?: any) => void;

export const leafletRasterLayer = (source: PMTiles, options: unknown) => {
  let loaded = false;
  let mimeType = "";
  const cls = L.GridLayer.extend({
    createTile: (coord: Coords, done: DoneCallback) => {
      const el = document.createElement("img");
      const controller = new AbortController();
      const signal = controller.signal;
      el.cancel = () => {
        controller.abort();
      };
      if (!loaded) {
        source.getHeader().then((header) => {
          if (header.tileType === TileType.Mvt) {
            console.error(
              "Error: archive contains MVT vector tiles, but leafletRasterLayer is for displaying raster tiles. See https://github.com/protomaps/PMTiles/tree/main/js for details."
            );
          } else if (header.tileType === 2) {
            mimeType = "image/png";
          } else if (header.tileType === 3) {
            mimeType = "image/jpeg";
          } else if (header.tileType === 4) {
            mimeType = "image/webp";
          } else if (header.tileType === 5) {
            mimeType = "image/avif";
          }
        });
        loaded = true;
      }
      source
        .getZxy(coord.z, coord.x, coord.y, signal)
        .then((arr) => {
          if (arr) {
            const blob = new Blob([arr.data], { type: mimeType });
            const imageUrl = window.URL.createObjectURL(blob);
            el.src = imageUrl;
            el.cancel = undefined;
            done(undefined, el);
          }
        })
        .catch((e) => {
          if (e.name !== "AbortError") {
            throw e;
          }
        });
      return el;
    },

    _removeTile: function (key: string) {
      const tile = this._tiles[key];
      if (!tile) {
        return;
      }

      if (tile.el.cancel) tile.el.cancel();

      tile.el.width = 0;
      tile.el.height = 0;
      tile.el.deleted = true;
      L.DomUtil.remove(tile.el);
      delete this._tiles[key];
      this.fire("tileunload", {
        tile: tile.el,
        coords: this._keyToTileCoords(key),
      });
    },
  });
  return new cls(options);
};

// copied from MapLibre /util/ajax.ts
type RequestParameters = {
  url: string;
  headers?: unknown;
  method?: "GET" | "POST" | "PUT";
  body?: string;
  type?: "string" | "json" | "arrayBuffer" | "image";
  credentials?: "same-origin" | "include";
  collectResourceTiming?: boolean;
};

type ResponseCallback = (
  error?: Error | null,
  data?: unknown | null,
  cacheControl?: string | null,
  expires?: string | null
) => void;

type Cancelable = {
  cancel: () => void;
};

export class Protocol {
  tiles: Map<string, PMTiles>;

  constructor() {
    this.tiles = new Map<string, PMTiles>();
  }

  add(p: PMTiles) {
    this.tiles.set(p.source.getKey(), p);
  }

  get(url: string) {
    return this.tiles.get(url);
  }

  tile = (
    params: RequestParameters,
    callback: ResponseCallback
  ): Cancelable => {
    if (params.type === "json") {
      const pmtilesUrl = params.url.substr(10);
      let instance = this.tiles.get(pmtilesUrl);
      if (!instance) {
        instance = new PMTiles(pmtilesUrl);
        this.tiles.set(pmtilesUrl, instance);
      }

      instance
        .getHeader()
        .then((h) => {
          const tilejson = {
            tiles: [`${params.url}/{z}/{x}/{y}`],
            minzoom: h.minZoom,
            maxzoom: h.maxZoom,
            bounds: [h.minLon, h.minLat, h.maxLon, h.maxLat],
          };
          callback(null, tilejson, null, null);
        })
        .catch((e) => {
          callback(e, null, null, null);
        });

      return {
        cancel: () => {},
      };
    }
    const re = new RegExp(/pmtiles:\/\/(.+)\/(\d+)\/(\d+)\/(\d+)/);
    const result = params.url.match(re);
    if (!result) {
      throw new Error("Invalid PMTiles protocol URL");
    }
    const pmtilesUrl = result[1];

    let instance = this.tiles.get(pmtilesUrl);
    if (!instance) {
      instance = new PMTiles(pmtilesUrl);
      this.tiles.set(pmtilesUrl, instance);
    }
    const z = result[2];
    const x = result[3];
    const y = result[4];

    const controller = new AbortController();
    const signal = controller.signal;
    const cancel = () => {
      controller.abort();
    };

    instance.getHeader().then((header) => {
      instance
        ?.getZxy(+z, +x, +y, signal)
        .then((resp) => {
          if (resp) {
            callback(
              null,
              new Uint8Array(resp.data),
              resp.cacheControl,
              resp.expires
            );
          } else {
            if (header.tileType === TileType.Mvt) {
              callback(null, new Uint8Array(), null, null);
            } else {
              callback(null, null, null, null);
            }
          }
        })
        .catch((e) => {
          if ((e as Error).name !== "AbortError") {
            callback(e, null, null, null);
          }
        });
    });
    return {
      cancel: cancel,
    };
  };
}