add support for layout.meta template for trace.name

- both in legend item and in hover labels!

Author: etpinard

src/components/fx/hover.js

@@ -738,6 +738,7 @@ function _hover(gd, evt, subplot, noHoverEvent) {
 var EXTRA_STRING_REGEX = /<extra>([\s\S]*)<\/extra>/;
 
 function createHoverText(hoverData, opts, gd) {
+    var fullLayout = gd._fullLayout;
     var hovermode = opts.hovermode;
     var rotateLabels = opts.rotateLabels;
     var bgColor = opts.bgColor;
@@ -925,6 +926,10 @@ function createHoverText(hoverData, opts, gd) {
         if(d.nameOverride !== undefined) d.name = d.nameOverride;
 
         if(d.name) {
+            if(fullLayout.meta) {
+                d.name = Lib.templateString(d.name, {meta: fullLayout.meta});
+            }
+
             name = svgTextUtils.plainText(d.name || '', {
                 len: d.nameLength,
                 allowedTags: ['br', 'sub', 'sup', 'b', 'i', 'em']

src/components/legend/draw.js

@@ -404,9 +404,13 @@ function drawTexts(g, gd, maxLength) {
     var trace = legendItem.trace;
     var isPie = Registry.traceIs(trace, 'pie');
     var traceIndex = trace.index;
-    var name = isPie ? legendItem.label : trace.name;
     var isEditable = gd._context.edits.legendText && !isPie;
 
+    var name = isPie ? legendItem.label : trace.name;
+    if(fullLayout.meta) {
+        name = Lib.templateString(name, {meta: fullLayout.meta});
+    }
+
     var textEl = Lib.ensureSingle(g, 'text', 'legendtext');
 
     textEl.attr('text-anchor', 'start')

test/image/baselines/layout_metatext.png

@@ -1,6 +1,8 @@
 {
   "data": [{
-    "y": [1, 2, 1]
+    "x": ["2019-01-01", "2019-02-10", "2019-03-24"],
+    "y": [1, 2, 1],
+    "name": "TRACE %{meta[3]}"
   }, {
     "type": "scatterpolar",
     "r": [1, 2, 1]
@@ -29,7 +31,6 @@
     "width": 700,
     "height": 800,
     "margin": {"b": 40},
-    "showlegend": false,
 
     "title": {"text": "This graph is %{meta[2]}"},
     "xaxis": {
@@ -78,7 +79,7 @@
       "text": "<i>N.B.</i> %{meta[2]}",
       "xref": "x",
       "yref": "y",
-      "x": 1,
+      "x": "2019-02-10",
       "y": 2
     }]
   }

test/image/mocks/layout_metatext.json

@@ -1734,6 +1734,32 @@ describe('hover info', function() {
             .then(done);
         });
     });
+
+    it('should work with trace.name linked to layout.meta', function(done) {
+        var gd = createGraphDiv();
+
+        Plotly.plot(gd, [{
+            y: [1, 1, 1],
+            name: '%{meta[0]}',
+            marker: {size: 40}
+        }, {
+            y: [1]
+        }], {
+            meta: ['yo!'],
+            width: 400,
+            height: 400
+        })
+        .then(function() { _hoverNatural(gd, 200, 200); })
+        .then(function() {
+            assertHoverLabelContent({
+                nums: '1',
+                name: 'yo!',
+                axis: '2'
+            });
+        })
+        .catch(failTest)
+        .then(done);
+    });
 });
 
 describe('hover info on stacked subplots', function() {