[Feature Request] Ability to count visible markers based on zoom level

[smallf00t]

Hi,

Is there a way to get the number of markers currently visible on the map for the current zoom level?
I couldn’t find any reference to this in the documentation.

This feature would be useful for UI updates based on the number of visible markers, similar to how platforms like FlightRadar display information dynamically.

[dceejay]

Hi - not presently. The worldmap-in node reports the current bounds every time the map is moved or zoomed.
It could count and report the number of markers contained - but what would you do with that information ? As you don't know which markers they are you would still need to filter server side if you only wanted to update those within the bounds anyway, so I'm not sure of the use case or utility of doing this client side ...

[smallf00t]

Hi - On certain web browsers, rendering a high number of markers (e.g., AIS vessel positions) significantly increases memory usage and causes performance degradation. Since zoom level information is already available, it should be leveraged to programmatically hide or remove specific layers when the zoom is below a defined threshold.

Expected Behavior:
Implement a data-driven event system—similar in concept to marker clustering—that dynamically filters or removes layers based on the current zoom level, reducing rendering load without relying solely on visual clustering.

[dceejay]

Again - if it's browser performance that is the issue then reducing the data server side surely makes more sense ? IE reduce it before sending - which you can do today if you like. If not then what algorithm do you suggest ? If total markers > x then ??? Which layers should be hidden - they don't have fixed names so ...? (again you can use the known zoom level on the server side to tell the browser to hide a layer today if you like). Also if you do it client side then you have to have sent them all in the first place... ie they need to be there before we can count how many - and then go oops too many... so surely the event system needs to be server side ? If you're not visually clustering then how would you know which markers to eliminate to best represent the remainder ?

Apologies - I just don't seem to be getting it....

[smallf00t]

Hello, these are AIS data for which I do not control the quantity.
There were two main interests:
Display the number of boats shown (each in layers specified by vessel type)
Handle the management of more or less important layers transparently for the user
In the end, using clustering will do the job. I am now looking into Leaflet to understand how the numbers displayed in Leaflet work. Thank you.

[dceejay]

When you get the data does it come as one large object or array ? or is it "live" data that arrives continuously ?
So now you don'r just want a count of markers - you want a count per layer ?