add some starter code to a _toImage attached to the div leveraging the snapshot button

Author: timelyportfolio

snapshot.md

@@ -10,6 +10,8 @@ Where do we attach toImage on the graph div?
     Is it _toImage?
     Do we just require /snapshot and bind to `this`?
 
+Will any of the chart types require special snapshot abilities or features?
+    
 What is the expected use case of our new ability?
 
 How do we piggyback on the snapshot button in the toolbar?
@@ -25,4 +27,16 @@ Are there reference points from other libraries that we could mimic or learn fro
 
 `Plotly.Snapshot.clone` could be used to resize by adding this to `options` when/if we use `Plotly.plot` with our cloned `div`.  We could also dynamically show a resulting view in a modal or something similar and adjust with `Plotly.relayout`.
 
-`Plotly.Snapshot.clone` by default sets `staticPlot:true` in `config`.
+`Plotly.Snapshot.clone` by default sets `staticPlot:true` in `config`.
+
+A very basic way to attach this assuming there is a modebar would be to do something like this.
+
+```
+gd._toImage = function(){this._fullLayout._modeBar.buttons.filter(function(btn){return btn[0].name==="toImage"})[0][0].click(this)}
+```
+
+```
+library(plotly)
+
+ggplotly(ggplot(cars,aes(speed,dist))+geom_point())
+```