use same contours logic in histogram2dcontour as for contour traces

- which fixes the references issues on relayout
  when `autocontour: true`

Author: etpinard

src/traces/contour/contours_defaults.js

@@ -0,0 +1,30 @@
+/**
+* Copyright 2012-2017, Plotly, Inc.
+* All rights reserved.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+'use strict';
+
+var Lib = require('../../lib');
+var attributes = require('./attributes');
+
+module.exports = function handleContourDefaults(traceIn, traceOut, coerce) {
+    var contourStart = Lib.coerce2(traceIn, traceOut, attributes, 'contours.start');
+    var contourEnd = Lib.coerce2(traceIn, traceOut, attributes, 'contours.end');
+    var missingEnd = (contourStart === false) || (contourEnd === false);
+
+    // normally we only need size if autocontour is off. But contour.calc
+    // pushes its calculated contour size back to the input trace, so for
+    // things like restyle that can call supplyDefaults without calc
+    // after the initial draw, we can just reuse the previous calculation
+    var contourSize = coerce('contours.size');
+    var autoContour;
+
+    if(missingEnd) autoContour = traceOut.autocontour = true;
+    else autoContour = coerce('autocontour', false);
+
+    if(autoContour || !contourSize) coerce('ncontours');
+};

src/traces/contour/defaults.js

@@ -13,7 +13,8 @@ var Lib = require('../../lib');
 
 var hasColumns = require('../heatmap/has_columns');
 var handleXYZDefaults = require('../heatmap/xyz_defaults');
-var handleStyleDefaults = require('../contour/style_defaults');
+var handleContoursDefaults = require('./contours_defaults');
+var handleStyleDefaults = require('./style_defaults');
 var attributes = require('./attributes');
 
 
@@ -31,21 +32,6 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     coerce('text');
     coerce('connectgaps', hasColumns(traceOut));
 
-    var contourStart = Lib.coerce2(traceIn, traceOut, attributes, 'contours.start'),
-        contourEnd = Lib.coerce2(traceIn, traceOut, attributes, 'contours.end'),
-        missingEnd = (contourStart === false) || (contourEnd === false),
-
-        // normally we only need size if autocontour is off. But contour.calc
-        // pushes its calculated contour size back to the input trace, so for
-        // things like restyle that can call supplyDefaults without calc
-        // after the initial draw, we can just reuse the previous calculation
-        contourSize = coerce('contours.size'),
-        autoContour;
-
-    if(missingEnd) autoContour = traceOut.autocontour = true;
-    else autoContour = coerce('autocontour', false);
-
-    if(autoContour || !contourSize) coerce('ncontours');
-
+    handleContoursDefaults(traceIn, traceOut, coerce);
     handleStyleDefaults(traceIn, traceOut, coerce, layout);
 };

src/traces/histogram2dcontour/defaults.js

@@ -12,6 +12,7 @@
 var Lib = require('../../lib');
 
 var handleSampleDefaults = require('../histogram2d/sample_defaults');
+var handleContoursDefaults = require('../contour/contours_defaults');
 var handleStyleDefaults = require('../contour/style_defaults');
 var attributes = require('./attributes');
 
@@ -30,5 +31,6 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     if(autocontour) coerce('ncontours');
     else coerce('contours.size');
 
+    handleContoursDefaults(traceIn, traceOut, coerce);
     handleStyleDefaults(traceIn, traceOut, coerce, layout);
 };