On update forced to previous view

[zacdav]

I'm currently using mapdeck to show some data in various cities, to facilitate this I've got a dropdown which triggers a view change to the specified location with some parameters. This works great, however, when you zoom in or pan and then update the data, the view is forced back to the original view of that location.

I've provided an application which demonstrates this, if you select Melbourne, zoom in, and hit refresh, it will transition back to the view.

Is there any way to avoid this behaviour? I've tried what seems to be most permutations of the parameters for the View/Zoom and layers but can't seem to get what I'm after.

Thanks

library(shiny)
library(shinydashboard)
library(mapdeck)
library(sf)

city_info <- list("Sydney, NSW"    = list("coords" = c(151.209333, -33.863168), "zoom" = 10, "gcc" = "1GSYD"),
                  "Melbourne, VIC" = list("coords" = c(144.966892, -37.817788), "zoom" = 10, "gcc" = "2GMEL"),
                  "Brisbane, QLD"  = list("coords" = c(153.020259, -27.465076), "zoom" = 10, "gcc" = "3GBRI"),
                  "Adelaide, SA"   = list("coords" = c(138.592169, -34.925565), "zoom" = 10, "gcc" = "4GADE"),
                  "Perth, WA"      = list("coords" = c(115.859835, -31.949616), "zoom" = 10, "gcc" = "5GPER"),
                  "Hobart, TAS"    = list("coords" = c(147.330575, -42.880892), "zoom" = 11, "gcc" = "6GHOB"),
                  "Darwin, NT"     = list("coords" = c(130.935697, -12.432844), "zoom" = 11, "gcc" = "7GDAR"),
                  "Canberra, ACT"  = list("coords" = c(149.125496, -35.299607), "zoom" = 11, "gcc" = "8ACTE"))

ui <- dashboardPage(
  dashboardHeader()
  , dashboardSidebar(
    selectInput(inputId = "select_state", label = NULL,
                choices = c("Sydney, NSW",
                            "Melbourne, VIC",
                            "Brisbane, QLD",
                            "Adelaide, SA",
                            "Perth, WA",
                            "Hobart, TAS",
                            "Darwin, NT",
                            "Canberra, ACT")),
    actionButton(inputId = "test_btn", label = "Refresh")
  )
  , dashboardBody(
    mapdeckOutput(outputId = "map")
  )
)
server <- function(input, output) {
  
  ## initialise a map
  output$map <- renderMapdeck({
    mapdeck(token = Sys.getenv("MAPBOX_API_TOKEN"),
            style = mapdeck_style("dark"))
  })
  
  # change map view (fly-to)
  observeEvent(input$select_state, {
    mapdeck_update("map") %>%
      mapdeck_view(
        location = city_info[[input$select_state]]$coords,
        zoom = city_info[[input$select_state]]$zoom,
        transition = "fly",
        duration = 2000) %>%
      clear_path("roads") %>%
      add_path(data = roads[1:150, ],
               stroke_width = 5,
               id = "FQID",
               auto_highlight = TRUE,
               update_view = FALSE,
               focus_layer = FALSE)
  })
  
  # update data
  observeEvent({input$test_btn}, {
    mapdeck_update("map") %>%
      add_path(data = roads[1:150, ],
               stroke_width = 5,
               id = "FQID",
               auto_highlight = TRUE,
               update_view = FALSE,
               focus_layer = FALSE)
  })
  
}

shinyApp(ui, server)

---

TODO

• revert back to 6.4.0 (or older versions) to see if the issue replicates - nope
• try using viewState in stead of initialViewState
• test 'fix' on google map

[SymbolixAU]

Thanks for reporting. I can't see what's triggering it to update the view so I'll need to investigate.

[SymbolixAU]

this is the line setProps({ layers: [...window[map_id + 'layers'] ] }) in here

function md_update_layer( map_id, layer_id, layer ) {

  var elem = md_findObjectElementByKey( window[map_id + 'map'].props.layers, 'id', layer_id );
  if ( elem != -1 ) {
  	window[ map_id + 'layers'][elem] = layer;
  } else {
  	window[map_id + 'layers'].push( layer );
  }
  window[map_id + 'map'].setProps({ layers: [...window[map_id + 'layers'] ] });
}

I don't know why updating a layer causes the map to re-focus back to its starting location. This may be a deck.gl issue. I'll keep digging...

[dcooley]

same behaviour in v7.0.0-beta

[SymbolixAU]

I've just committed a temporary fix to the master branch. I'm not completely convinced it's fully fixed yet so will keep this issue open until I've done more testing.

[SymbolixAU]

A side effect of [https://github.com/SymbolixAU/mapdeck/commit/c723bacbde18c710a5555f6a1c701b358cc59ff5] is when you remove a layer it will re-focus back to the starting state of the map

library(shiny)
library(shinydashboard)
library(mapdeck)

ui <- dashboardPage(
	dashboardHeader()
	, dashboardSidebar(
		actionButton(inputId = "roads", label = "roads")
	)
	, dashboardBody(
		mapdeckOutput(outputId = "map")
	)
)

server <- function(input, output) {
	
	## initialise a map
	output$map <- renderMapdeck({
		mapdeck(
			# location = c(144.9, -37)
			# , zoom = 5
			)
	})
	
	## use an observer to add and remove layers
	observeEvent({input$roads},{
		
		if ( input$roads %% 2 == 1 ) {
			
			mapdeck_update(map_id = "map") %>%
				add_path(
					data = roads
					, layer_id = "myRoads"
					, stroke_colour = "RIGHT_LOC"
					, update_view = T
				)
		} else {
			mapdeck_update(map_id = "map") %>%
				clear_path(layer_id = "myRoads")
		}
	})
}

shinyApp(ui, server)

When adding the roads, the map focuses on the layer. When they are cleared, it goes back to starting state.

The saga continues...

[SymbolixAU]

When they are cleared, it goes back to starting state.

only IFF the user hasn't interacted with the map!

in the shiny example above, if you don't interact with the map between button presses, the view is returned to the previous state. However, if you do interact with the map, it stays in the last state you interacted with.

[dcooley]

@zacdav have you had a chance to test the latest dev version?

[zacdav]

@dcooley I'll have a go tomorrow on the example I had previously.

[zacdav]

@SymbolixAU @dcooley
Confirmed this is no longer misbehaving

[dcooley]

ok thanks. I'll close this now, but may reopen in the future if it's still not right.