Added styles for PointDraw (#3819) (#4063)

holoviews/plotting/bokeh/callbacks.py

@@ -976,14 +976,17 @@ def _create_style_callback(self, cds, glyph, length_var):
         cds.js_on_change('data', cb)
 
 
-class PointDrawCallback(CDSCallback):
+class PointDrawCallback(GlyphDrawCallback):
 
     def initialize(self, plot_id=None):
+        plot = self.plot
         stream = self.streams[0]
         renderers = [self.plot.handles['glyph_renderer']]
         kwargs = {}
         if stream.num_objects:
             kwargs['num_objects'] = stream.num_objects
+        if stream.styles:
+            self._create_style_callback(plot.handles['cds'], plot.handles['glyph'], 'x')
         point_tool = PointDrawTool(drag=all(s.drag for s in self.streams),
                                    empty_value=stream.empty_value,
                                    renderers=renderers, **kwargs)

holoviews/streams.py

@@ -1069,12 +1069,17 @@ class PointDraw(CDSStream):
     num_objects: int
         The number of polygons that can be drawn before overwriting
         the oldest polygon.
+
+    styles: dict
+    A dictionary specifying lists of styles to cycle over whenever
+    a new Point glyph is drawn.
     """
 
-    def __init__(self, empty_value=None, drag=True, num_objects=0, **params):
+    def __init__(self, empty_value=None, drag=True, num_objects=0, styles={}, **params):
         self.drag = drag
         self.empty_value = empty_value
         self.num_objects = num_objects
+        self.styles = styles
         super(PointDraw, self).__init__(**params)
 
     @property