mapdeck_view() doesn't use current viewState properties

[hdmm3]

mapdeck_view() doesn't use current viewState properties

[dcooley]

Thanks for the extra detail. And I've been meaining to revisit the viewState logic / code so thanks for bringing this up. When I first implemented it I had a lot of issues getting it to work in both a shiny & non-shiny environment, and getting the map & layers to update correctly.

I'll try and set some time aside next week to look at this in more detail.

[dcooley]

Thanks for the PR - now merged

[dcooley]

Something in this commit causes the map to freeze, so I've reverted to the commit before this.

[dcooley]

something else was wrong so I've fully reverted this

[hdmm3]

Hi @dcooley, first of all apologies for those half-baked PRs. This time I'll share my thoughts first. I've been digging about the intended behaviour of deck.gl when using either initialViewState or viewState props. Here are some of my interpretations of what's going on when using the initialViewState prop:

• At creation the viewState object will simply be set to the input initialViewState prop.
• When using initialViewState, the onViewStateChange callback called during controller interaction, is internally followed by an update to the internal viewState here. This update will track changes to the viewState in a nested object viewState[viewId]. That way multiple views can save their own viewState independently. Most importantly, the current view state will be located in that nested object, instead of at the root viewState. Also the viewManager will be updated.
• Currently, md_change_location overwrites the internal viewState through setProps({initialViewState}) effectively destroying the nested object created during onViewStateChange.
• If a call to md_change_location is made after controller interaction, reading the values of the viewState object will pick stale values of the view instead of the most current ones.

In order to avoid fully overwriting the viewState, the initialViewState prop could be set in md_change_location as follows:

window[map_id + 'map'].setProps({
      initialViewState: {
        ...window[map_id + 'map'].viewState,
        [map_id]: {
          longitude: currentLon,
          latitude: currentLat,
          zoom: currentZoom,
          maxZoom: currentMaxZoom,
          minZoom: currentMinZoom,
          maxPitch: currentMaxPitch,
          minPitch: currentMinPitch,
          pitch: currentPitch,
          bearing: currentBearing,
          transitionInterpolator: transition === "fly" ? new deck.FlyToInterpolator() : new deck.LinearInterpolator(),
          transitionDuration: duration,
          controller: true}        
      }
    });

As such, the current viewState for the map_id could be retrieved using viewManager.getViewState(), as follows:

currentViewState = window[map_id + 'map'].viewManager?.getViewState(map_id) || window[map_id + 'map'].viewState;

getViewState() seems to be the safest approach. I'm not sure if after deck.gl 8+ the "default-view" viewId will even occur when the DeckGL views prop defines views with id as it's done with mapdeck.

I hope this helps!