relayout: merge all array container update into one block

- simply use p.set() to update
- the recent relinkPrivateKeys modifs allow for
  gd.layout and gd._fullLayout array containers to not
  have the same length
- set undo val to null when adding a new item, to remove
  when Queue.undo() is called.

Author: etpinard

src/plot_api/plot_api.js

@@ -1815,8 +1815,7 @@ function _relayout(gd, aobj) {
             // trunk nodes (everything except the leaf)
             ptrunk = p.parts.slice(0, pend).join('.'),
             parentIn = Lib.nestedProperty(gd.layout, ptrunk).get(),
-            parentFull = Lib.nestedProperty(fullLayout, ptrunk).get(),
-            diff;
+            parentFull = Lib.nestedProperty(fullLayout, ptrunk).get();
 
         if(vi === undefined) continue;
 
@@ -1950,42 +1949,17 @@ function _relayout(gd, aobj) {
             drawOne(gd, objNum, p.parts.slice(2).join('.'), aobj[ai]);
             delete aobj[ai];
         }
-        else if(p.parts[0] === 'images') {
-            var update = Lib.objectFromPath(ai, vi);
-            Lib.extendDeepAll(gd.layout, update);
+        else if(
+            Plots.layoutArrayContainers.indexOf(p.parts[0]) !== -1 ||
+            (p.parts[0] === 'mapbox' && p.parts[1] === 'layers')
+        ) {
 
-            Registry.getComponentMethod('images', 'supplyLayoutDefaults')(gd.layout, gd._fullLayout);
-            Registry.getComponentMethod('images', 'draw')(gd);
-        }
-        else if(p.parts[0] === 'mapbox' && p.parts[1] === 'layers') {
-            Lib.extendDeepAll(gd.layout, Lib.objectFromPath(ai, vi));
-
-            // append empty container to mapbox.layers
-            // so that relinkPrivateKeys does not complain
-
-            var fullLayers = (gd._fullLayout.mapbox || {}).layers || [];
-            diff = (p.parts[2] + 1) - fullLayers.length;
-
-            for(i = 0; i < diff; i++) fullLayers.push({});
-
-            flags.doplot = true;
-        }
-        else if(p.parts[0] === 'updatemenus') {
-            Lib.extendDeepAll(gd.layout, Lib.objectFromPath(ai, vi));
-
-            var menus = gd._fullLayout.updatemenus || [];
-            diff = (p.parts[2] + 1) - menus.length;
-
-            for(i = 0; i < diff; i++) menus.push({});
-            flags.doplot = true;
-        }
-        else if(p.parts[0] === 'sliders') {
-            Lib.extendDeepAll(gd.layout, Lib.objectFromPath(ai, vi));
-
-            var sliders = gd._fullLayout.sliders || [];
-            diff = (p.parts[2] + 1) - sliders.length;
+            // if adding a new item, make sure undo will remove it
+            if(isNumeric(p.parts[plen - 1]) && p.get() === undefined) {
+                undoit[ai] = null;
+            }
 
-            for(i = 0; i < diff; i++) sliders.push({});
+            p.set(vi);
             flags.doplot = true;
         }
         // alter gd.layout

src/plots/plots.js

@@ -1424,6 +1424,9 @@ plots.extendObjectWithContainers = function(dest, src, containerPaths) {
     return dest;
 };
 
+plots.dataArrayContainers = ['transforms'];
+plots.layoutArrayContainers = ['annotations', 'shapes', 'images', 'sliders', 'updatemenus'];
+
 /*
  * Extend a trace definition. This method:
  *
@@ -1433,7 +1436,7 @@ plots.extendObjectWithContainers = function(dest, src, containerPaths) {
  * The result is the original object reference with the new contents merged in.
  */
 plots.extendTrace = function(destTrace, srcTrace) {
-    return plots.extendObjectWithContainers(destTrace, srcTrace, ['transforms']);
+    return plots.extendObjectWithContainers(destTrace, srcTrace, plots.dataArrayContainers);
 };
 
 /*
@@ -1446,13 +1449,7 @@ plots.extendTrace = function(destTrace, srcTrace) {
  * The result is the original object reference with the new contents merged in.
  */
 plots.extendLayout = function(destLayout, srcLayout) {
-    return plots.extendObjectWithContainers(destLayout, srcLayout, [
-        'annotations',
-        'shapes',
-        'images',
-        'sliders',
-        'updatemenus'
-    ]);
+    return plots.extendObjectWithContainers(destLayout, srcLayout, plots.layoutArrayContainers);
 };
 
 /**