bar: Add attributes base, offset and width

Author: n-riesco

src/traces/bar/attributes.js

@@ -48,6 +48,41 @@ module.exports = {
         ].join(' ')
     },
 
+    base: {
+        valType: 'any',
+        arrayOk: true,
+        role: 'info',
+        description: [
+            'Sets where the bar base is drawn (in position axis units).',
+            'In *stack* or *relative* barmode,',
+            'traces that set *base* will be excluded',
+            'and drawn in *overlay* mode instead.'
+        ].join(' ')
+    },
+
+    offset: {
+        valType: 'number',
+        arrayOk: true,
+        role: 'info',
+        description: [
+            'Shifts the position where the bar is drawn',
+            '(in position axis units).',
+            'In *group* barmode,',
+            'traces that set *offset* will be excluded',
+            'and drawn in *overlay* mode instead.'
+        ].join(' ')
+    },
+
+    width: {
+        valType: 'number',
+        min: 0,
+        arrayOk: true,
+        role: 'info',
+        description: [
+            'Sets the bar width (in position axis units).'
+        ].join(' ')
+    },
+
     marker: marker,
 
     r: scatterAttrs.r,

src/traces/bar/defaults.js

@@ -30,6 +30,9 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     }
 
     coerce('orientation', (traceOut.x && !traceOut.y) ? 'h' : 'v');
+    coerce('base');
+    coerce('offset');
+    coerce('width');
     coerce('text');
 
     handleStyleDefaults(traceIn, traceOut, coerce, defaultColor, layout);