From ef1969889efdcec9ee588a5d2f405b6d554a59ab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Rivi=C3=A8re?= <fil@rezo.net>
Date: Mon, 29 Jul 2024 01:21:55 +0200
Subject: [PATCH] fix autoHeight and outerRange for empty scale domains (#1864)

closes #1856
---
 src/dimensions.js               |  5 ++---
 src/plot.js                     |  1 +
 test/output/autoHeightEmpty.svg | 25 +++++++++++++++++++++++++
 test/plots/autoheight.ts        |  5 +++++
 test/plots/index.ts             |  1 +
 5 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 test/output/autoHeightEmpty.svg
 create mode 100644 test/plots/autoheight.ts

diff --git a/src/dimensions.js b/src/dimensions.js
index cb7a7f13a1..ada0f64787 100644
--- a/src/dimensions.js
+++ b/src/dimensions.js
@@ -92,7 +92,7 @@ function autoHeight(
   {projection, aspectRatio},
   {width, marginTopDefault, marginRightDefault, marginBottomDefault, marginLeftDefault}
 ) {
-  const nfy = fy ? fy.scale.domain().length : 1;
+  const nfy = fy ? fy.scale.domain().length || 1 : 1;
 
   // If a projection is specified, compute an aspect ratio based on the domain,
   // defaulting to the projection’s natural aspect ratio (if known).
@@ -103,8 +103,7 @@ function autoHeight(
     const lar = Math.max(0.1, Math.min(10, far)); // clamp the aspect ratio to a “reasonable” value
     return Math.round((width - marginLeftDefault - marginRightDefault) * lar + marginTopDefault + marginBottomDefault);
   }
-
-  const ny = y ? (isOrdinalScale(y) ? y.scale.domain().length : Math.max(7, 17 / nfy)) : 1;
+  const ny = y ? (isOrdinalScale(y) ? y.scale.domain().length || 1 : Math.max(7, 17 / nfy)) : 1;
 
   // If a desired aspect ratio is given, compute a default height to match.
   if (aspectRatio != null) {
diff --git a/src/plot.js b/src/plot.js
index a091d8d8a8..1e8daf22b8 100644
--- a/src/plot.js
+++ b/src/plot.js
@@ -732,6 +732,7 @@ function actualDimensions({fx, fy}, dimensions) {
 
 function outerRange(scale) {
   const domain = scale.domain();
+  if (domain.length === 0) return [0, scale.bandwidth()];
   let x1 = scale(domain[0]);
   let x2 = scale(domain[domain.length - 1]);
   if (x2 < x1) [x1, x2] = [x2, x1];
diff --git a/test/output/autoHeightEmpty.svg b/test/output/autoHeightEmpty.svg
new file mode 100644
index 0000000000..6277e5e83a
--- /dev/null
+++ b/test/output/autoHeightEmpty.svg
@@ -0,0 +1,25 @@
+<svg class="plot" fill="currentColor" font-family="system-ui, sans-serif" font-size="10" text-anchor="middle" width="640" height="400" viewBox="0 0 640 400" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <style>
+    :where(.plot) {
+      --plot-background: white;
+      display: block;
+      height: auto;
+      height: intrinsic;
+      max-width: 100%;
+    }
+
+    :where(.plot text),
+    :where(.plot tspan) {
+      white-space: pre;
+    }
+  </style>
+  <g aria-label="fy-axis label" transform="translate(37.5,0.5)">
+    <text transform="translate(600,157.5) rotate(-90)">path</text>
+  </g>
+  <g aria-label="y-axis label" text-anchor="start" transform="translate(-36.5,-16.5)">
+    <text y="0.71em" transform="translate(40,0)">visitors</text>
+  </g>
+  <g aria-label="x-axis label" transform="translate(0.5,27.5)">
+    <text transform="translate(320,315)">date</text>
+  </g>
+</svg>
\ No newline at end of file
diff --git a/test/plots/autoheight.ts b/test/plots/autoheight.ts
new file mode 100644
index 0000000000..4fb89e79ce
--- /dev/null
+++ b/test/plots/autoheight.ts
@@ -0,0 +1,5 @@
+import * as Plot from "@observablehq/plot";
+
+export async function autoHeightEmpty() {
+  return Plot.rectY([], {x: "date", y: "visitors", fy: "path"}).plot();
+}
diff --git a/test/plots/index.ts b/test/plots/index.ts
index f82888ee67..6b4742539e 100644
--- a/test/plots/index.ts
+++ b/test/plots/index.ts
@@ -27,6 +27,7 @@ export * from "./athletes-sport-sex.js";
 export * from "./athletes-sport-weight.js";
 export * from "./athletes-weight-cumulative.js";
 export * from "./athletes-weight.js";
+export * from "./autoheight.js";
 export * from "./autoplot.js";
 export * from "./availability.js";
 export * from "./axis-filter.js";