@allmaps/render/dist/tilecache/CacheableImageDataTile.js

Render functions for WebGL and image buffers

import { fetchUrl } from "@allmaps/stdlib";
import { CacheableTile } from "./CacheableTile.js";
import { WarpedMapEvent, WarpedMapEventType } from "../shared/events.js";
class CacheableImageDataTile extends CacheableTile {
  /**
   * Fetch the tile and create its ImageData object.
   *
   * @returns
   */
  async fetch() {
    try {
      const response = await fetchUrl(
        this.tileUrl,
        {
          signal: this.abortController.signal
        },
        this.fetchFn
      );
      const width = this.tile.tileZoomLevel.width;
      const height = this.tile.tileZoomLevel.height;
      const blob = await response.blob();
      const bitmap = await createImageBitmap(blob);
      const canvas = new OffscreenCanvas(width, height);
      const context = canvas.getContext("2d");
      if (!context) {
        throw new Error("Could not create OffscreenCanvas context");
      }
      context.drawImage(bitmap, 0, 0);
      this.data = context.getImageData(0, 0, width, height);
      this.dispatchEvent(
        new WarpedMapEvent(WarpedMapEventType.TILEFETCHED, this.tileUrl)
      );
    } catch (err) {
      if (err instanceof Error && err.name === "AbortError") ;
      else {
        this.dispatchEvent(
          new WarpedMapEvent(WarpedMapEventType.TILEFETCHERROR, this.tileUrl)
        );
      }
    }
    return this.data;
  }
  static createFactory() {
    return (fetchableTile, fetchFn) => new CacheableImageDataTile(fetchableTile, fetchFn);
  }
}
export {
  CacheableImageDataTile
};
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