mark scale map

Author: mbostock

src/channel.js

@@ -5,13 +5,16 @@ import {isSymbol, maybeSymbol} from "./symbols.js";
 import {maybeReduce} from "./transforms/group.js";
 
 // TODO Type coercion?
-export function Channel(data, {scale, type, value, filter, hint}) {
+export function Channel(data, {scale, type, value, filter, hint}, scaleOverride) {
   let V = valueof(data, value);
 
-  // For color and symbol scales, allow the channel to opt-out of the scale by
-  // providing literal values. In the case of symbols, we must further promote
-  // symbol names (e.g., "plus") to a symbol instance (symbolPlus).
-  if (V) {
+  // For color and symbol scales, if a scale is not explicitly overridden,
+  // ignore the channel’s default scale if the channel values are literal. In
+  // the case of symbols, we must further promote symbol names (e.g., "plus") to
+  // a symbol instance (symbolPlus).
+  if (scaleOverride !== undefined) {
+    scale = scaleOverride;
+  } else if (V) {
     const is = scale === "color" ? isColor : scale === "symbol" ? isSymbol : null;
     if (is && isFirst(V, is) && isEvery(V, is)) {
       if (is === isSymbol) V = map(V, maybeSymbol);
@@ -29,18 +32,20 @@ export function Channel(data, {scale, type, value, filter, hint}) {
   };
 }
 
-export function Channels(descriptors, data) {
-  return Object.fromEntries(Object.entries(descriptors).map(([name, channel]) => [name, Channel(data, channel)]));
+export function Channels(channels, data, scales) {
+  return Object.fromEntries(
+    Object.entries(channels).map(([name, channel]) => {
+      return [name, Channel(data, channel, scales?.[name])];
+    })
+  );
 }
 
 // TODO Use Float64Array for scales with numeric ranges, e.g. position?
 export function valueObject(channels, scales) {
   return Object.fromEntries(
     Object.entries(channels).map(([name, {scale: scaleName, value}]) => {
       let scale;
-      if (scaleName !== undefined) {
-        scale = scales[scaleName];
-      }
+      if (scaleName != null) scale = scales[scaleName];
       return [name, scale === undefined ? value : map(value, scale)];
     })
   );

src/mark.js

@@ -23,7 +23,8 @@ export class Mark {
       marginBottom = margin,
       marginLeft = margin,
       clip,
-      channels: extraChannels
+      channels: extraChannels,
+      scale
     } = options;
     this.data = data;
     this.sort = isDomainSort(sort) ? sort : null;
@@ -54,6 +55,7 @@ export class Mark {
     this.marginBottom = +marginBottom;
     this.marginLeft = +marginLeft;
     this.clip = maybeClip(clip);
+    this.scales = scale;
     // Super-faceting currently disallow position channels; in the future, we
     // could allow position to be specified in fx and fy in addition to (or
     // instead of) x and y.
@@ -70,7 +72,7 @@ export class Mark {
     let data = arrayify(this.data);
     if (facets === undefined && data != null) facets = [range(data)];
     if (this.transform != null) ({facets, data} = this.transform(data, facets)), (data = arrayify(data));
-    const channels = Channels(this.channels, data);
+    const channels = Channels(this.channels, data, this.scales);
     if (this.sort != null) channelDomain(channels, facetChannels, data, this.sort); // mutates facetChannels!
     return {data, facets, channels};
   }

src/marks/contour.js

@@ -174,7 +174,7 @@ function contourGeometry({thresholds, interval, ...options}) {
     return {
       data: contourData,
       facets: contourFacets,
-      channels: Channels(this.contourChannels, contourData)
+      channels: Channels(this.contourChannels, contourData, this.scales)
     };
   });
 }