add handleAnnotations method to scene proto

- call it when ticks require a change and
  when user drags and scroll on plot

Author: etpinard

src/plots/gl2d/camera.js

@@ -113,6 +113,7 @@ function createCamera(scene) {
                     result.lastInputTime = Date.now();
                     unSetAutoRange();
                     scene.cameraChanged();
+                    scene.handleAnnotations();
                 }
                 break;
         }
@@ -152,6 +153,7 @@ function createCamera(scene) {
                 result.lastInputTime = Date.now();
                 unSetAutoRange();
                 scene.cameraChanged();
+                scene.handleAnnotations();
                 break;
         }
 

src/plots/gl2d/scene2d.js

@@ -9,6 +9,7 @@
 
 'use strict';
 
+var Registry = require('../../registry');
 var Axes = require('../../plots/cartesian/axes');
 var Fx = require('../../plots/cartesian/graph_interact');
 
@@ -323,10 +324,25 @@ proto.cameraChanged = function() {
         this.glplotOptions.ticks = nextTicks;
         this.glplotOptions.dataBox = camera.dataBox;
         this.glplot.update(this.glplotOptions);
+        this.handleAnnotations();
+
         relayoutCallback(this);
     }
 };
 
+proto.handleAnnotations = function() {
+    var gd = this.graphDiv,
+        annotations = this.fullLayout.annotations;
+
+    for(var i = 0; i < annotations.length; i++) {
+        var ann = annotations[i];
+
+        if(ann.xref === this.xaxis._id && ann.yref === this.yaxis._id) {
+            Registry.getComponentMethod('annotations', 'drawOne')(gd, i);
+        }
+    }
+};
+
 proto.destroy = function() {
     var traces = this.traces;