Add equal earth projection

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Added
 
+- New `equal_earth` map projection (`+proj=eqearth`).
+
 - New caching layer that wraps any `Reader` with an in-memory, writeable cache
  backend (currently duckdb or sqlite), making write-constrained databases
  usable and avoiding repeated remote reads during interactive iteration.

doc/syntax/coord/crs.qmd

@@ -101,6 +101,7 @@ More information about them can be found on the [PRØJ website](https://proj.org
 | Azimuthal Equidistant | `azimuthal_equidistant` | (0, 0) | NA | `+proj=aeqd` |
 | Interrupted Goode Homolosine | `igh` | 0 | NA | `+proj=igh` |
 | Robinson | `robinson` | 0 | NA | `+proj=robin` |
+| Equal Earth | `equal_earth` | 0 | NA | `+proj=eqearth` |
 
 The way to draw an unsupported map is to use the `target` setting.
 Unsupported maps are likely drawn without projection-appropriate clipping.

src/plot/projection/coord/map_projections.rs

@@ -37,6 +37,7 @@ pub const NAMED_PROJECTIONS: &[&str] = &[
  "azimuthal_equidistant",
  "igh",
  "robinson",
+ "equal_earth",
 ];
 
 // =============================================================================
@@ -338,6 +339,7 @@ macro_rules! build_projection {
  "eqc" | "equirectangular" => Arc::new(Equirectangular { lon_0 }),
  "cea" | "equal_area" => Arc::new(CylindricalEqualArea { lon_0 }),
  "robin" | "robinson" => Arc::new(Robinson { lon_0 }),
+ "eqearth" | "equal_earth" => Arc::new(EqualEarth { lon_0 }),
  "moll" | "mollweide" => Arc::new(Mollweide { lon_0 }),
  "sinu" | "sinusoidal" => Arc::new(Sinusoidal { lon_0 }),
  "eck4" | "eckert4" => Arc::new(Eckert4 { lon_0 }),
@@ -786,6 +788,26 @@ impl MapProjectionTrait for Robinson {
  }
 }
 
+#[derive(Debug, Clone)]
+pub struct EqualEarth {
+ pub lon_0: f64,
+}
+
+impl MapProjectionTrait for EqualEarth {
+ fn proj_code(&self) -> &'static str {
+ "eqearth"
+ }
+ fn display_name(&self) -> &'static str {
+ "Equal Earth"
+ }
+ fn origin(&self) -> (f64, f64) {
+ (self.lon_0, 0.0)
+ }
+ fn to_proj_str(&self) -> String {
+ format!("+proj=eqearth +lon_0={}", self.lon_0)
+ }
+}
+
 #[derive(Debug, Clone)]
 pub struct Mollweide {
  pub lon_0: f64,
@@ -1448,6 +1470,29 @@ mod tests {
  assert!(proj.slit_wkt(0.005).is_none());
  }
 
+ #[test]
+ fn equal_earth_from_name_and_proj_str() {
+ let mut props = Parameters::new();
+ props.insert("origin".to_string(), ParameterValue::Number(11.0));
+ let proj = build_map_projection_trait(Some("equal_earth"), &props).unwrap();
+ assert_eq!(proj.proj_code(), "eqearth");
+ assert_eq!(proj.origin(), (11.0, 0.0));
+ assert_eq!(proj.to_proj_str(), "+proj=eqearth +lon_0=11");
+
+ let proj = build_from_proj_str("+proj=eqearth +lon_0=11");
+ assert_eq!(proj.proj_code(), "eqearth");
+ assert_eq!(proj.to_proj_str(), "+proj=eqearth +lon_0=11");
+ }
+
+ #[test]
+ fn equal_earth_covers_whole_globe() {
+ let proj = build_from_proj_str("+proj=eqearth");
+ assert_eq!(proj.lat_bounds(), (-90.0, 90.0));
+ let wkt = proj.visible_area_wkt().unwrap();
+ assert!(wkt.starts_with("POLYGON(("), "{wkt}");
+ assert!(proj.slit_wkt(0.005).is_none());
+ }
+
  #[test]
  fn visible_area_gnomonic() {
  let proj = build_from_proj_str("+proj=gnom +lat_0=90 +lon_0=0");