expose fillet attribute for treemap

Author: emilykl

src/traces/treemap/attributes.js

@@ -141,7 +141,19 @@ module.exports = {
 
         line: sunburstAttrs.marker.line,
 
-        editType: 'calc'
+        fillet: {
+            valType: 'number',
+            min: 0,
+            // max: 10, // TODO: Do we need a max?
+            dflt: 0,
+            editType: 'plot',
+            description: [
+                'Sets the rounding of corners (in px).'
+            ].join(' ')
+        },
+
+        editType: 'calc',
+
     },
         colorScaleAttrs('marker', {
             colorAttr: 'colors',

src/traces/treemap/defaults.js

@@ -85,6 +85,8 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     coerce('marker.pad.r', headerSize / 4);
     coerce('marker.pad.b', bottomText ? headerSize : headerSize / 4);
 
+    coerce('marker.fillet');
+
     traceOut._hovered = {
         marker: {
             line: {

src/traces/treemap/plot_one.js

@@ -217,12 +217,8 @@ module.exports = function plotOne(gd, cd, element, transitionOpts, drawDescendan
         var dy = _y1 - _y0;
         if(!dx || !dy) return '';
 
-        var FILLET = 0; // TODO: may expose this constant
-
-        var r = (
-            dx > 2 * FILLET &&
-            dy > 2 * FILLET
-        ) ? FILLET : 0;
+        var FILLET = trace.marker.fillet;
+        var r = dx > 2 * FILLET && dy > 2 * FILLET ? FILLET : Math.min(dx, dy) / 2;
 
         var arc = function(rx, ry) { return r ? 'a' + pos(r, r) + ' 0 0 1 ' + pos(rx, ry) : ''; };