DRY up scatter / scattergl fill ordering in linkTraces

Author: etpinard

src/traces/scatter/link_traces.js

@@ -75,9 +75,16 @@ module.exports = function linkTraces(gd, plotinfo, cdscatter) {
                 }
             }
 
+            if(trace.fill && (
+                trace.fill.substr(0, 6) === 'tozero' || trace.fill === 'toself' ||
+                (trace.fill.substr(0, 2) === 'to' && !trace._prevtrace))
+            ) {
+                trace._ownfill = true;
+            }
+
             prevtraces[group] = trace;
         } else {
-            trace._prevtrace = trace._nexttrace = null;
+            trace._prevtrace = trace._nexttrace = trace._ownfill = null;
         }
     }
 

src/traces/scatter/plot.js

@@ -93,19 +93,10 @@ function createFills(gd, traceJoin, plotinfo) {
         var trace = d[0].trace;
 
         var fillData = [];
-        if(trace.fill && (trace.fill.substr(0, 6) === 'tozero' || trace.fill === 'toself' ||
-                (trace.fill.substr(0, 2) === 'to' && !trace._prevtrace))
-        ) {
-            fillData = ['_ownFill'];
-        }
-        if(trace._nexttrace) {
-            // make the fill-to-next path now for the NEXT trace, so it shows
-            // behind both lines.
-            fillData.push('_nextFill');
-        }
+        if(trace._ownfill) fillData.push('_ownFill');
+        if(trace._nexttrace) fillData.push('_nextFill');
 
-        var fillJoin = fills.selectAll('g')
-            .data(fillData, identity);
+        var fillJoin = fills.selectAll('g').data(fillData, identity);
 
         fillJoin.enter().append('g');
 

src/traces/scattergl/index.js

@@ -436,16 +436,8 @@ function plot(gd, subplot, cdata) {
                 var last, j;
 
                 var fillData = [];
-                if(trace.fill && (trace.fill.substr(0, 6) === 'tozero' || trace.fill === 'toself' ||
-                        (trace.fill.substr(0, 2) === 'to' && !trace._prevtrace))
-                ) {
-                    fillData.push(i)
-                }
-                if(trace._nexttrace) {
-                    // make the fill-to-next path now for the NEXT trace, so it shows
-                    // behind both lines.
-                    fillData.push(i + 1);
-                }
+                if(trace._ownfill) fillData.push(i);
+                if(trace._nexttrace) fillData.push(i + 1);
                 if(fillData.length) scene.fillOrder[i] = fillData;
 
                 var pos = [], srcPos = (lineOptions && lineOptions.positions) || stash.positions;