Heatmap Support

[mpopolin]

Any support for heatmap as plugins?

[ibrierley]

I haven't seen one yet, but I think there are for Leaflet.js so I don't think it would be that tricky to adapt one.

[tprebs]

I have written a heatmap plugin for an ongoing project which I am planning on pulling out into its own repo I just haven't had the time yet. It generates heatmaps similar to the screenshot below. If this is what you are looking for I will try and make time this weekend to pull it out into a separate repo.

[ibrierley]

Looks good, I think it would be appreciated by a few.

[mpopolin]

I have written a heatmap plugin for an ongoing project which I am planning on pulling out into its own repo I just haven't had the time yet. It generates heatmaps similar to the screenshot below. If this is what you are looking for I will try and make time this weekend to pull it out into a separate repo.

this is pretty much what i need, that would be great to have. If I can help with something please let me know.

[tprebs]

I will try and get an alpha release out over the weekend that you can play around with

[tprebs]

Sorry for the delay. I've been flat out at work for the last few months. I will put up a slimmed down version over the next couple of days to get some feedback on. I have been half way through optimising the caching of the gridded heatmap data but have not had time to finish it off yet. I will put it up as is then add the gridded cache to a separate branch and carry on working on it there.

[ibrierley]

I'm guessing the author is busy, it's been a long while, so I'm tempted to move this to a discussion as @JaffaKetchup suggested. I like the idea of heatmap support, probably as a plugin, and am happy to help with it if others are interested.
@tprebs if you're still lurking and have any suggestions or bits of code, even if not working, like the visual elements, feel free to add, as it may set the ball rolling!

[tprebs]

Apologies for the radio silence I haven't been working with flutter_map for a year or so and this completely fell off my radar. I have pulled the fulttermap_heatmap plugin out of the project and updated it to be compatible with dart null safety and to the latest version of flutter_map.

I will get it published to pub.dev today but in the meantime, you can find it here https://github.com/tprebs/fluttermap_heatmap

There are a few things still outstanding (e.g. gridded data source provider isn't complete - which would be very useful for tens of thousands of data points) but as an alpha release its good to go.

As this was originally extracted from a project it is not massively configurable but I am happy to add accept PRs for any config options which may be needed if this is useful for your projects

UPDATE

I would also like to caveat that this may no longer be the optimal solution for flutter_maps v3. I have not fully re-read the documentation yet, but this plugin was developed against a more limited futter_map implementation (0.14) where the best option at the time was to implement this as a TileLayer with most of the heavy lifting done by a custom tile provider. From memory, one of the limiting factors was the lack of callbacks for drag events. The addition of onPointerDown and onPointerUp callbacks means this could now probably be implemented outside of a TileLayer

[ibrierley]

Great stuff, thanks Thomas.

[tprebs]

I was looking though the documentation to work out why, after updating to flutter_map 3.1.0, the heatmap tile layer does not show until the map is interacted with. I have a suspicion it is related to the reset stream.

https://docs.fleaflet.dev/usage/layers/tile-layer/other-options#reset-stream-reset

The documentation mentions that this is now less important in v3 (I added the reset stream to flutter_map when originally developing this plugin). Is there now a better alternative for working with dynamic tiles/data other than reset stream, or is it less important as there is an alternative mechanism for clearing the cache of tiles for the most common use case (WMS layers)

[JaffaKetchup]

@tprebs Great news, I'll add the plugin as beta to the docs, just let me know once it's all ready!

In terms of the reset stream, that was mainly used for resetting tiles after the urlTemplate changed, but doesn't appear to be necessary for that anymore. If it's even still connected to anything internally, it might still be useful.
#1475 is making some big changes to the TileLayer, so it's probably worth preparing for v4 instead of v3. v4 should be along relatively soon.
It's probably also worth noting the FlutterMapState.of(context) method that can be used in all children. That essentially connects a layer to the map.

[tprebs]

Thanks for the heads up @JaffaKetchup. You are indeed correct, the behaviour has changed since the addition of the TileManager. Back when the reset stream was added, the tile cache was managed within the TileLayerState which cleared the cache and then reset the view, displaying the new tiles. Now the reset listener just clears the cache but doesn't load any tiles until the map is interacted with.

I think there is still value in maintaining the flexibility on being able to clear and reload the tile cache by choice. A couple of use cases I have used in the past:

1. The heatmap where the tiles are dynamically generated and cached. I could just generate a unique url every time the request changes but that is less than ideal
2. I worked on an app which triggered the generation of custom styled WMTS tiles. collect a few parameters, send it server-side and the WMTS tiles were regenerated. as the url was fixed e.g. dynamic-tile-server.com/draft/b3NtOjIz/{z}/{x}/{y}.png, I had to trigger the clearing of the cache once the tiles had regenerated.

I will look at #1475 and see if there is an alternative approach after the refactor. If not I am happy to create a PR to fix the reset behaviour

[JaffaKetchup]

It appears as though it is intact, although it should probably be tested, as the underlying method has been changed. But it at least looks like it should work.

flutter_map/lib/src/layer/tile_layer/tile_layer.dart

Lines 325 to 331 in 654db14

	if (widget.reset != null) {
	_resetSub = widget.reset?.listen(
	(_) => _tileImageManager.removeAll(
	widget.evictErrorTileStrategy,
	),
	);
	}

[tprebs]

Now available on pub.dev https://pub.dev/packages/flutter_map_heatmap.

[JaffaKetchup]

Great! Once you have a moment, can you prepare it for v4 so I can add it to the plugins list with the v4 release?

[tprebs]

All done @JaffaKetchup . The next version will be released against fluttermap v4

[tprebs]

@JaffaKetchup https://github.com/tprebs/fluttermap_heatmap/releases/tag/v0.0.3 is now available and supports the v4. Do you want me to create a PR to update the docs or would you prefer to do it?

[JaffaKetchup]

@tprebs Great! All done: https://docs.fleaflet.dev/plugins/list#parsing-and-creating-map-features.