add a shorter default header when there's no header specified

Author: monfera

src/traces/table/constants.js

@@ -9,26 +9,27 @@
 'use strict';
 
 module.exports = {
-    maxDimensionCount: 60,
-    overdrag: 45,
     cellPad: 8,
+    columnExtentOffset: 10,
+    columnTitleOffset: 28,
+    emptyHeaderHeight: 16,
     latexCheck: /^\$.*\$$/,
-    wrapSplitCharacter: ' ',
-    wrapSpacer: ' ',
-    lineBreaker: '<br>',
-    uplift: 5,
     goldenRatio: 1.618,
-    columnTitleOffset: 28,
-    columnExtentOffset: 10,
-    transitionEase: 'cubic-out',
-    transitionDuration: 100,
-    releaseTransitionEase: 'cubic-out',
+    lineBreaker: '<br>',
+    maxDimensionCount: 60,
+    overdrag: 45,
     releaseTransitionDuration: 120,
-    scrollbarWidth: 8,
+    releaseTransitionEase: 'cubic-out',
     scrollbarCaptureWidth: 18,
-    scrollbarOffset: 5,
     scrollbarHideDelay: 1000,
     scrollbarHideDuration: 1000,
+    scrollbarOffset: 5,
+    scrollbarWidth: 8,
+    transitionDuration: 100,
+    transitionEase: 'cubic-out',
+    uplift: 5,
+    wrapSpacer: ' ',
+    wrapSplitCharacter: ' ',
     cn: {
         // general class names
         table: 'table',

src/traces/table/data_preparation_helper.js

@@ -24,7 +24,7 @@ module.exports = function calc(gd, trace) {
     var domain = trace.domain;
     var groupWidth = Math.floor(gd._fullLayout._size.w * (domain.x[1] - domain.x[0]));
     var groupHeight = Math.floor(gd._fullLayout._size.h * (domain.y[1] - domain.y[0]));
-    var headerRowHeights = headerValues.length ? headerValues[0].map(function() {return trace.header.height;}) : [];
+    var headerRowHeights = trace.header.values.length ? headerValues[0].map(function() {return trace.header.height;}) : [c.emptyHeaderHeight];
     var rowHeights = cellsValues.length ? cellsValues[0].map(function() {return trace.cells.height;}) : [];
     var headerHeight = headerRowHeights.reduce(function(a, b) {return a + b;}, 0);
     var scrollHeight = groupHeight - headerHeight;