local images for raster tiles

[sqcsabbey]

I'm trying to draw gridlines over the map, and I found a JS plugin, but I'd like to do this with Flutter; does anyone know of an existing solution?

---

Because I wasn't able to find one, I think I'll have to implement it, and I had some implementation questions:

I'd like to add a raster layer, and I'd like to create/cache the images for it locally, within the app, using Dart. I'm not sure where to write the image files or how to refer to them.

In the examples, I see this code:

  static Future<void> addRaster(MapLibreMapController controller) async {
    await controller.addSource(
      "watercolor",
      const RasterSourceProperties(
          tiles: [
            'https://stamen-tiles.a.ssl.fastly.net/watercolor/{z}/{x}/{y}.jpg'
          ],
          tileSize: 256,
          attribution:
              'Map tiles by <a target="_top" rel="noopener" href="http://stamen.com">Stamen Design</a>, under <a target="_top" rel="noopener" href="http://creativecommons.org/licenses/by/3.0">CC BY 3.0</a>. Data by <a target="_top" rel="noopener" href="http://openstreetmap.org">OpenStreetMap</a>, under <a target="_top" rel="noopener" href="http://creativecommons.org/licenses/by-sa/3.0">CC BY SA</a>'),
    );
    await controller.addLayer(
        "watercolor", "watercolor", const RasterLayerProperties());
  }

And I found this helpful issue comment for saving and using local glyphs.

My guess is I can get it working from these 2 examples, but I wasn't sure if there was a recommended way of doing this, or if the RasterSourceProperties tiles property can even use a local filesystem url.

So, should this work? Or are there some gotchas with this approach?