Send 'plotly_click' and 'plotly_selected' events to shiny when in shinyMode

[cpsievert]

@chriddyp @jp @cldougl

I talked to @jcheng5 today. He suggested that we don't yet rely on crosstalk, as it's still very experimental, and may never be officially supported.

Later I realized that, in #312, crosstalk is only used to send plotly event data to the shiny server. It turns out that isn't super hard to implement using shiny alone, so I've done that here.

Here is a barebones example (source)

To see how the interface for accessing plotly user event data has changed for those older examples, see cpsievert/apps@5633b6e (ignore the inline stuff, cc @pssguy)

A few things left to sort through:

1. In the basic example above, notice that if you select point(s), then double click to unselect, the selection doesn't clear in the linked views. @etpinard, if possible, a 'plotly_doubleClick' event would be a huge help here!
2. Do we want to support 'plotly_hover'? If so, that probably means we should clear the selection on 'plotly_unhover', but I imagine this quickly leads to glitchy behavior when hovering over a bunch of points.
3. Should we provide an option to not send plotly user selections to shiny?

[jackparmer]

Nice! ping @alexcjohnson re "plotly_doubleClick" event ^^^

[etpinard]

@cpsievert adding a doubleclick emitter would be a 2-line patch.

The only thing we need to discuss, is what the eventData should be on doubleclick?

The same as the old selection, an empty object, or something else?

[cpsievert]

@etpinard I don't think I have a preference for eventData as I'll probably send null regardless

[Vestaxis]

+1 from me too for plotly_doubleClick. Would be really great to have. Only reason why I'm occasionally using ggplot in Shiny apps.

[jackparmer]

Hey @cpsievert , is it still possible to get plotly_hover and plotly_unhover in here? The folks over at climate corporation asked for it a few weeks ago, and I forgot about this PR being open.
(/cc @royr2 @charleyferrari @yankev )

[jackparmer]

A few other folks are already trying to hack access to the hover events:
http://bl.ocks.org/ramnathv/dd524aa6ce9d90fc80cf
http://stackoverflow.com/questions/34031570/mouseover-in-plotly-and-shiny

[cldougl]

Nice!!!

[jackparmer]

🎉 🎉 🎉

[tmhdunn]

Is there any possibility of getting plotly click event data for the white space? Would be useful in making something where the user can click to add data points.