custom size for addEasyprint with leaflet.extras2

Question

I'm creating some html files for colleagues where they can explore a leaflet map interactively, then save a copy for presentations.

Unfortunately the downloads from addEasyprint in leaflet.extras2 are fairly low resolution. I've been unable to figure out how to configure a custom size. The documentation hints at custom sizes (say, width = 3000 pixels by height = 1800 pixels), but I can't quite get there - myself or trying with AI! What could I add below to define a custom size?

library(dplyr)
library(sf)
library(leaflet)
library(leaflet.extras2)

check <- st_as_sf(tibble(latitude = c(48, 48.00001, 49), 
                         longitude = c(-89, -89.0001, -90)), 
                  coords = c("longitude", "latitude"),
                  crs = "+proj=longlat +datum=WGS84 +no_defs")

check_bounds <- c(-87, 47, -91, 50)
leaflet() %>%
  fitBounds(check_bounds[1], check_bounds[2], 
            check_bounds[3], check_bounds[4]) %>%
  addTiles() %>%
  addMarkers(data = check) %>% 
  addProviderTiles("Esri.WorldTopoMap",group = "Topographic") %>%
  addProviderTiles("Esri.WorldImagery", group = "Imagery") %>%
  addLayersControl(
    baseGroups = c("Topographic", "Imagery"),
    options = layersControlOptions(collapsed = FALSE)
  ) |> 
  addEasyprint(options = easyprintOptions(
    title = "Save map to PNG",
    position = "topleft",
    filename = "check",
    hideControlContainer = FALSE, 
    sizeModes = c("CurrentSize"),
    exportOnly = TRUE
  ))

Answer 1

Not an expert but I found this github issue, where the author of the package has created a new branch allowing "dpi" to be specified. If you install this updated version of the package using the remotes package, does it solve your problem?

E.g.

library(dplyr)
library(sf)
library(leaflet)
options(timeout = 600)
remotes::install_github("https://github.com/trafficonese/leaflet.extras2/tree/print_dpi")
library(leaflet.extras2)

check <- st_as_sf(tibble(latitude = c(48, 48.00001, 49), 
                         longitude = c(-89, -89.0001, -90)), 
                  coords = c("longitude", "latitude"),
                  crs = "+proj=longlat +datum=WGS84 +no_defs")

check_bounds <- c(-87, 47, -91, 50)
leaflet() %>%
  fitBounds(check_bounds[1], check_bounds[2], 
            check_bounds[3], check_bounds[4]) %>%
  addTiles() %>%
  addMarkers(data = check) %>% 
  addProviderTiles("Esri.WorldTopoMap",group = "Topographic") %>%
  addProviderTiles("Esri.WorldImagery", group = "Imagery") %>%
  addLayersControl(
    baseGroups = c("Topographic", "Imagery"),
    options = layersControlOptions(collapsed = FALSE)
  ) |> 
  addEasyprint(options = easyprintOptions(
    title = "Save map to PNG",
    position = "topleft",
    filename = "check",
    hideControlContainer = FALSE, 
    sizeModes = list("Custom Landscape"=list(
      width= 3000,
      height= 1600,
      name = "A custom landscape size tooltip",
      className= 'customCssClass')),
    exportOnly = TRUE,
    dpi = 600
  ))

The resulting png is larger, so perhaps the resolution is better? Maybe you can tweak the 'custom size' and dpi to get the output you want?