From 228c5f5e39c75eece115ebdad919a15383e6aa7e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Rivi=C3=A8re?= <fil@rezo.net>
Date: Mon, 5 Dec 2022 11:48:13 +0100
Subject: [PATCH] projection.domain accepts an iterable

closes #1148
---
 README.md                               |  2 +-
 src/projection.js                       | 13 ++++++++++++-
 test/plots/projection-fit-antarctica.js |  6 +++---
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 72af6a9d3e..0623e35455 100644
--- a/README.md
+++ b/README.md
@@ -341,7 +341,7 @@ If the **projection** option is specified as an object, the following additional
 * projection.**parallels** - the [standard parallels](https://github.com/d3/d3-geo/blob/main/README.md#conic_parallels) (for conic projections only)
 * projection.**precision** - the [sampling threshold](https://github.com/d3/d3-geo/blob/main/README.md#projection_precision)
 * projection.**rotate** - a two- or three- element array of Euler angles to rotate the sphere
-* projection.**domain** - a GeoJSON object to fit in the center of the frame
+* projection.**domain** - a GeoJSON object (or an iterable of GeoJSON objects) to fit in the center of the frame
 * projection.**inset** - inset by the given amount in pixels when fitting to the frame (default zero)
 * projection.**insetLeft** - inset from the left edge of the frame (defaults to inset)
 * projection.**insetRight** - inset from the right edge of the frame (defaults to inset)
diff --git a/src/projection.js b/src/projection.js
index 07ab9a70f6..11061eefa1 100644
--- a/src/projection.js
+++ b/src/projection.js
@@ -74,7 +74,18 @@ export function Projection(
   // Otherwise wrap the projection stream with a suitable transform. If a domain
   // is specified, fit the projection to the frame. Otherwise, translate.
   if (domain) {
-    const [[x0, y0], [x1, y1]] = geoPath(projection).bounds(domain);
+    const fitDomain = domain.type ? [domain] : domain;
+    let x0 = Infinity,
+      y0 = x0,
+      x1 = -x0,
+      y1 = x1;
+    for (const domain of fitDomain) {
+      const [[xl, yl], [xh, yh]] = geoPath(projection).bounds(domain);
+      if (xl < x0) x0 = xl;
+      if (xh > x1) x1 = xh;
+      if (yl < y0) y0 = yl;
+      if (yh > y1) y1 = yh;
+    }
     const k = Math.min(dx / (x1 - x0), dy / (y1 - y0));
     if (k > 0) {
       tx -= (k * (x0 + x1) - dx) / 2;
diff --git a/test/plots/projection-fit-antarctica.js b/test/plots/projection-fit-antarctica.js
index 430c7e1ba8..9c5ff1ed7a 100644
--- a/test/plots/projection-fit-antarctica.js
+++ b/test/plots/projection-fit-antarctica.js
@@ -4,7 +4,7 @@ import {feature} from "topojson-client";
 
 export default async function () {
   const world = await d3.json("data/countries-50m.json");
-  const domain = feature(
+  const ata = feature(
     world,
     world.objects.countries.geometries.find((d) => d.properties.name === "Antarctica")
   );
@@ -12,7 +12,7 @@ export default async function () {
     width: 600,
     height: 600,
     inset: 30,
-    projection: {type: "azimuthal-equidistant", rotate: [0, 90], domain},
-    marks: [Plot.graticule({clip: "frame"}), Plot.geo(domain, {clip: "frame", fill: "currentColor"}), Plot.frame({})]
+    projection: {type: "azimuthal-equidistant", rotate: [0, 90], domain: [ata]},
+    marks: [Plot.graticule({clip: "frame"}), Plot.geo(ata, {clip: "frame", fill: "currentColor"}), Plot.frame({})]
   });
 }