tip ignores literal colors (#2091)

src/channel.js

@@ -48,11 +48,13 @@ export function inferChannelScale(name, channel) {
       case "stroke":
       case "color":
         channel.scale = scale !== true && isEvery(value, isColor) ? null : "color";
+        channel.defaultScale = "color";
         break;
       case "fillOpacity":
       case "strokeOpacity":
       case "opacity":
         channel.scale = scale !== true && isEvery(value, isOpacity) ? null : "opacity";
+        channel.defaultScale = "opacity";
         break;
       case "symbol":
         if (scale !== true && isEvery(value, isSymbol)) {
@@ -61,6 +63,7 @@ export function inferChannelScale(name, channel) {
         } else {
           channel.scale = "symbol";
         }
+        channel.defaultScale = "symbol";
         break;
       default:
         channel.scale = registry.has(name) ? name : null;

src/legends.js

@@ -45,7 +45,7 @@ function legendOptions({className, ...context}, {label, ticks, tickFormat} = {},
 
 function legendColor(color, {legend = true, ...options}) {
   if (legend === true) legend = color.type === "ordinal" ? "swatches" : "ramp";
-  if (color.domain === undefined) return;
+  if (color.domain === undefined) return; // no identity legend
   switch (`${legend}`.toLowerCase()) {
     case "swatches":
       return legendSwatches(color, options);

src/marks/tip.js

@@ -345,7 +345,11 @@ function getSourceChannels(channels, scales) {
   for (const key in channels) {
     if (key in sources || key in format || ignoreChannels.has(key)) continue;
     const source = getSource(channels, key);
-    if (source) sources[key] = source;
+    if (source) {
+      // Ignore color channels if the values are all literal colors.
+      if (source.scale == null && source.defaultScale === "color") continue;
+      sources[key] = source;
+    }
   }
 
   // And lastly facet channels, but only if this mark is faceted.