"dev mode" that displays map properties

[MilesMcBain]

What do you want the feature to do?
Display me the current zoom level, pitch, aspect, and location of the mapdeck map.

From digging around in the JS console, these are available at run time through a call like:

window['htmlwidget-61c5ac303a9850ca1046map'].viewState

The idea is this would help the developer frame up the default views for dashboards, reports, etc.

Similar examples
mapview displays the current cursor long lat and zoom.

[SymbolixAU]

Display me the current zoom level, pitch, aspect, and location of the mapdeck map.

Are you wanting this displayed in the javascript console?

---

If you're in shiny mode you can observe the view changes using

observeEvent({intput$myMap_view_change},{
  ## do something with input$myMap_view_change
})

[SymbolixAU]

mapview displays the current cursor long lat and zoom.

And do you know where in the code this happens?

[tim-salabim]

the code for the mousecoordinates is here:

https://github.com/r-spatial/leafem/blob/master/R/mousecoords.R#L53-L167

[dcooley]

Thanks @tim-salabim - I now understand!

[tim-salabim]

@dcooley I am still planning to integrate mapdeck in mapview as a rendering platform. Maybe this is a good point to start the process... We can either expand the mousecoords above to work also on mapdeck objects or have something similar in mapdeck itself and I'll wrap it in the above. Also, it may be desirable to transfer the text based onRender solution to a native JavaScript plugin (seems more elegant and better to debug). Let me know what you think

[SymbolixAU]

@tim-salabim I think Mile's suggestion of using the viewState object is the best approach for Deckgl, as it always exists and I just have to read its properties.

Still keen on supporting getting it working in mapview. Are you going to Rstudio::conf?

[tim-salabim]

Perfect, that'll make it easy for me to wrap it.

To get mapdeck + mapview on the way, the most important function to expand is leafem::addFeatures which, on first inspection, shouldn't be too hard.

Hopefully I will find some time over the coming weeks to get this done.

[dcooley]

@MilesMcBain were you thinking this feature would only be used for developing & debugging?

Here's a quick example which prints the current viewState object, and updates every time you pan, zoom, drag the map

[tim-salabim]

That was easier than anticipated! Right now leafem::addFeatures uses:

• add_pointcloud for point features (i.e. sfc_*POINT) - though elevation argument doesn't seem to be respected for sf data
• add_path for line features
• add_polygon for polygon features

E.g. for points:

Maybe there is some smart way of letting the user choose how to render different features given that mapdeck has multiple ways of rendering e.g. lines.

The only requirement for leafem::addFeatures is a valid sf/sp object. So everything that mapdeck supports for these types should be supported in leafem::addFeatures via ...

This is a major step towards supporting mapdeck in mapview. What's left is automatic popup generation (in package leafpop) and a default map setup (in package mapview).

[dcooley]

Maybe you could use the same rules I apply for add_sf ?

[tim-salabim]

I'll look into those.

[MilesMcBain]

were you thinking this feature would only be used for developing & debugging?

That's the usecase yes, only used transiently, so appearance not that important. For context, I do a lot of embedding maps in HTML reports made with RMarkdown.

So right now, once I have a mapdeck with layers just so, I then have a bit of a time puzzling out a nice default view. My go to currently is mapview or sometimes mapedit which gets me a location and zoom. I don't have anything for pitch and aspect though, so that's usually a bit of trial and error that can consume time.

edit: spurious words

[tim-salabim]

From a mapview point of view I'd be grateful if we could specify which of the information to query/display. E.g. current view bounds are not important as they presumably depend on the current window size. Hope this is not asking too much.

[SymbolixAU]

@MilesMcBain If you want to try it out you can grab it from

devtools::install_gihtub("SymbolixAU/mapdeck", ref = "issue238")

@tim-salabim I'll take it into consideration, thanks.

[SymbolixAU]

@MilesMcBain Does this add_view_state() function work as you intended?

[MilesMcBain]

Yes it does! Thank you very much 😄

[SymbolixAU]

Cool - I'll get it documented and into master

[SymbolixAU]

Noting here - #211 (comment) - the impact to this issue should be minimal as the data is just printed to the map/screen.