protomaps leaflet layer making multiple calls to backend on render?

[csbrown]

protomaps leaflet layer making multiple calls to backend on render?

[bdon]

Yes, the internal data storage for tiles is on a 1024x1024 grid, and features can exist slightly outside of 1024 depending on the buffer size in at tile creation (tippecanoe).

It is not generally possible to determine correct polygon centroids on tiled data, because a polygon may be clipped at tile edges. You may be able to take advantage of Tippecanoe features to pre-calculate centroids and store those as points in the tileset.

[bdon]

when you create a leafletLayer pass debug: "blue" or any color and it draws additional information on top

For a single zoom level it will make as many tile data requests as # of tiles needed to cover your screen. The defaults in v1.x are a single data tile (request) covers 1024x1024 screen pixels. In 2.x this will change to 512x512 screen pixels. So for a browser window taking up part of the screen there could be 6 requests. For fullscreen on a 32 inch monitor it could be more like 12. there are also 1-4 additional requests of directory fetch overhead.

[bdon]

This looks expected because every 256x256 screen tile is drawn independently, and the feature detection is buffered to implement line stroking without edge artifacts. if Maui is close to the corner of a tile the symbolizer could be called up to 4 times.

I don't see any duplicate calls to the backend in my network tab. Do you see any visual errors?

[csbrown]

Ah. I am calculating centroids for painting in my application. It seems that when polygons are split over tiles, I will need to do something interesting.

Did you notice the large coordinate values? Are those modulo the map size in some way?

[csbrown]

"I don't see any duplicate calls to the backend in my network tab"

I see that your network tab shows a "byte range" - the latest two requests were for adjacent byte ranges. Is it normal to have multiple requests on a zoom event, then?

Are you using some sort of tool to help debug this? Your screenshot looks like it includes a lot of extremely helpful information. :)

[csbrown]

Thanks, this has all been extremely helpful.