fix raster crash when colors are set by hand (identity scale) (#1237)

* fix raster crash when colors are set by hand (identity scale)

* formatHex (hex is deprecated)

Author: Fil

src/marks/raster.js

@@ -98,7 +98,7 @@ export class Raster extends AbstractRaster {
     return super.scale(channels, scales, context);
   }
   render(index, scales, channels, dimensions, context) {
-    const {color} = scales;
+    const color = scales.color ?? ((x) => x);
     const {x: X, y: Y} = channels;
     const {document} = context;
     const [x1, y1, x2, y2] = renderBounds(channels, dimensions, context);

test/output/rasterCa55Color.svg

@@ -33,6 +33,24 @@ export async function rasterCa55Nearest() {
   return rasterCa55({interpolate: "nearest"});
 }
 
+export async function rasterCa55Color() {
+  const ca55 = await d3.csv("data/ca55-south.csv", d3.autoType);
+  const domain = {type: "MultiPoint", coordinates: ca55.map((d) => [d.GRID_EAST, d.GRID_NORTH])};
+  return Plot.plot({
+    width: 640,
+    height: 484,
+    projection: {type: "reflect-y", inset: 3, domain},
+    marks: [
+      Plot.raster(ca55, {
+        x: "GRID_EAST",
+        y: "GRID_NORTH",
+        interpolate: "random-walk",
+        fill: (d) => d3.hcl(d.MAG_IGRF90, 120, 80).formatHex()
+      })
+    ]
+  });
+}
+
 export async function contourCa55() {
   return plotCa55((ca55) =>
     Plot.contour(ca55, {