Add support to plotly_deselect event (#1542)

* Add trace.on_deselect() method to register callback to be executed on deselection (double click)

js/src/Figure.js

@@ -750,6 +750,10 @@ var FigureView = widgets.DOMWidgetView.extend({
                     function (update) {
                         that.handle_plotly_selected(update)
                     });
+                that.el.on("plotly_deselect",
+                    function (update) {
+                        that.handle_plotly_deselect(update)
+                    });
                 that.el.on("plotly_doubleclick",
                     function (update) {
                         that.handle_plotly_doubleclick(update)
@@ -1080,6 +1084,17 @@ var FigureView = widgets.DOMWidgetView.extend({
     handle_plotly_selected: function (data) {
         this._send_points_callback_message(data, "plotly_selected");
     },
+
+    /**
+     * Handle plotly_deselect events emitted by the Plotly.js library
+     * @param data
+     */
+    handle_plotly_deselect: function (data) {
+        data = {
+            points : []
+        }
+        this._send_points_callback_message(data, "plotly_deselect");
+    },    
 
     /**
      * Build and send a points callback message to the Python side

plotly/basedatatypes.py

@@ -4120,6 +4120,9 @@ def __init__(self, plotly_name, **kwargs):
         # ### Callbacks to be called on selection ###
         self._select_callbacks = []
 
+        # ### Callbacks to be called on deselect ###
+        self._deselect_callbacks = []
+
         # ### Trace index in figure ###
         self._trace_ind = None
 
@@ -4387,6 +4390,74 @@ def _dispatch_on_selection(self,
         for callback in self._select_callbacks:
             callback(self, points, selector)
 
+    # deselect
+    # --------
+    def on_deselect(
+            self,
+            callback,
+            append=False):
+        """
+        Register function to be called when the user deselects points
+        in this trace using doubleclick.
+
+        Note: Callbacks will only be triggered when the trace belongs to a
+        instance of plotly.graph_objs.FigureWidget and it is displayed in an
+        ipywidget context. Callbacks will not be triggered on figures
+        that are displayed using plot/iplot.
+
+        Parameters
+        ----------
+        callback
+            Callable function that accepts 3 arguments
+
+            - this trace
+            - plotly.callbacks.Points object
+
+        append : bool
+            If False (the default), this callback replaces any previously
+            defined on_deselect callbacks for this trace. If True,
+            this callback is appended to the list of any previously defined
+            callbacks.
+
+        Returns
+        -------
+        None
+
+        Examples
+        --------
+        >>> from plotly.callbacks import Points
+        >>> points = Points()
+
+        >>> def deselect_fn(trace, points):
+        ...     inds = points.point_inds
+        ...     # Do something
+
+        >>> trace.on_deselect(deselect_fn)
+
+        Note: The creation of the `points` object is optional,
+        it's simply a convenience to help the text editor perform completion
+        on the `points` arguments inside `selection_fn`
+        """
+        if not append:
+            del self._deselect_callbacks[:]
+
+        if callback:
+            self._deselect_callbacks.append(callback)
+
+    def _dispatch_on_deselect(self, points):
+        """
+        Dispatch points info to deselection callbacks
+        """
+        if 'selectedpoints' in self:
+            # Update the selectedpoints property, which will notify all views
+            # of the selection change.  This is a special case because no
+            # restyle event is emitted by plotly.js on selection events
+            # even though these events update the selectedpoints property.
+            self.selectedpoints = None
+
+        for callback in self._deselect_callbacks:
+            callback(self, points)
+
 
 class BaseFrameHierarchyType(BasePlotlyType):
     """

plotly/basewidget.py

@@ -737,6 +737,8 @@ def _handler_js2py_pointsCallback(self, change):
                 trace._dispatch_on_unhover(points, state)
             elif event_type == 'plotly_selected':
                 trace._dispatch_on_selection(points, selector)
+            elif event_type == 'plotly_deselect':
+                trace._dispatch_on_deselect(points)
 
         self._js2py_pointsCallback = None
 

plotlywidget/static/index.js

@@ -13409,6 +13409,10 @@ var FigureView = widgets.DOMWidgetView.extend({
                     function (update) {
                         that.handle_plotly_selected(update)
                     });
+                that.el.on("plotly_deselect",
+                    function (update) {
+                        that.handle_plotly_deselect(update)
+                    });
                 that.el.on("plotly_doubleclick",
                     function (update) {
                         that.handle_plotly_doubleclick(update)
@@ -13739,6 +13743,17 @@ var FigureView = widgets.DOMWidgetView.extend({
     handle_plotly_selected: function (data) {
         this._send_points_callback_message(data, "plotly_selected");
     },
+
+    /**
+     * Handle plotly_deselect events emitted by the Plotly.js library
+     * @param data
+     */
+    handle_plotly_deselect: function (data) {
+        data = {
+            points : []
+        }
+        this._send_points_callback_message(data, "plotly_deselect");
+    },    
 
     /**
      * Build and send a points callback message to the Python side