scattermapbox: implement placeholder logic

- so plotting that data-pt less traces do result in mapbox errors.

Author: etpinard

src/traces/scattermapbox/convert.js

@@ -42,8 +42,8 @@ module.exports = function convert(calcTrace) {
         symbol: symbol
     };
 
-    // early return is not visible
-    if(!isVisible) return opts;
+    // early return if not visible or placeholder
+    if(!isVisible || calcTrace[0].placeholder) return opts;
 
     // fill layer and line layer use the same coords
     var coords;

src/traces/scattermapbox/hover.js

@@ -19,6 +19,8 @@ module.exports = function hoverPoints(pointData, xval, yval) {
         xa = pointData.xa,
         ya = pointData.ya;
 
+    if(cd[0].placeholder) return;
+
     // compute winding number about [-180, 180] globe
     var winding = (xval >= 0) ?
             Math.floor((xval + 180) / 360) :

test/jasmine/tests/scattermapbox_test.js

@@ -244,13 +244,12 @@ describe('scattermapbox convert', function() {
 
     function _convert(trace) {
         var gd = { data: [trace] };
-
         Plots.supplyDefaults(gd);
 
         var fullTrace = gd._fullData[0];
-        var calcTrace = ScatterMapbox.calc(gd, fullTrace);
-        calcTrace[0].trace = fullTrace;
+        Plots.doCalcdata(gd, fullTrace);
 
+        var calcTrace = gd.calcdata[0];
         return convert(calcTrace);
     }
 
@@ -353,9 +352,9 @@ describe('scattermapbox convert', function() {
 
         assertVisibility(opts, ['none', 'visible', 'none', 'visible']);
 
-        var lineCoords = [[
+        var lineCoords = [
             [10, 20], [20, 20], [30, 10], [20, 10], [10, 20]
-        ]];
+        ];
 
         expect(opts.line.geojson.coordinates).toEqual(lineCoords, 'have correct line coords');
 
@@ -413,6 +412,20 @@ describe('scattermapbox convert', function() {
         expect(radii).toBeCloseToArray([0, 1, 0], 'link features to correct stops');
     });
 
+    it('for input only blank pts', function() {
+        var opts = _convert(Lib.extendFlat({}, base, {
+            mode: 'lines',
+            lon: ['', null],
+            lat: [null, ''],
+            fill: 'toself'
+        }));
+
+        assertVisibility(opts, ['none', 'none', 'none', 'none']);
+
+        expect(opts.line.geojson.coordinates).toEqual([], 'have correct line coords');
+        expect(opts.fill.geojson.coordinates).toEqual([], 'have correct fill coords');
+    });
+
     function assertVisibility(opts, expectations) {
         var actual = ['fill', 'line', 'circle', 'symbol'].map(function(l) {
             return opts[l].layout.visibility;