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New V8 context

Source: R/new_v8_context.R
new_v8_context.Rd

Create a new V8 JavaScript context preloaded with the D3.js geospatial stack.

Usage

new_v8_context(
  libs = c("https://cdn.jsdelivr.net/npm/d3@7", "https://cdn.jsdelivr.net/npm/d3-geo@3",
    "https://cdn.jsdelivr.net/npm/d3-geo-polygon@2",
    "https://cdn.jsdelivr.net/npm/d3-geo-projection@4"),
  verbose = TRUE
)

Arguments

libs

Character vector of JavaScript library URLs to load. By default, libraries are loaded from the jsDelivr CDN. Users may replace these with local files, pinned versions, or alternative CDNs.

verbose

Logical. If TRUE, prints loading status for each library.

Value

A V8 JavaScript context with the D3.js geospatial stack loaded and ready for cartographic computations.

Details

This function initializes a fresh V8 JavaScript runtime and automatically loads the latest versions of the required D3.js libraries from the jsDelivr CDN.

The following JavaScript libraries are loaded by default:

- d3 (core library): https://cdn.jsdelivr.net/npm/d3 - d3-geo (spherical geometry and geographic projections): https://cdn.jsdelivr.net/npm/d3-geo - d3-geo-projection (extended cartographic projections): https://cdn.jsdelivr.net/npm/d3-geo-projection - d3-geo-polygon (spherical polygon clipping): https://cdn.jsdelivr.net/npm/d3-geo-polygon

These libraries are fetched dynamically at runtime from the jsDelivr CDN, ensuring that the most recent compatible versions are used unless explicitly overridden via the `libs` argument.

All projections computed in this environment rely on D3.js spherical geometry, where the Earth is modeled as a sphere rather than an ellipsoid. This allows fast and consistent computation of map projections and geometric transformations.

Examples

ct <- planisphere::new_v8_context()
#> V8 engine 12.4.254.21 initialized
#> Loading additional JavaScript libraries
#> [OK] https://cdn.jsdelivr.net/npm/d3@7
#> [OK] https://cdn.jsdelivr.net/npm/d3-geo@3
#> [OK] https://cdn.jsdelivr.net/npm/d3-geo-polygon@2
#> [OK] https://cdn.jsdelivr.net/npm/d3-geo-projection@4
#> Planisphere is ready
# Then:
library(sf)
world <- st_read(
  system.file("gpkg/land.gpkg", package = "planisphere"),
  quiet = TRUE
)
out <- planisphere::project(x = world, proj = "InterruptedBoggs", ct = ct)