Ensure HoloViews matplotlib output uses tight layout (#2920)

panel/pane/holoviews.py

@@ -259,7 +259,10 @@ def _get_model(self, doc, root=None, parent=None, comm=None):
 
         kwargs = {p: v for p, v in self.param.values().items()
                   if p in Layoutable.param and p != 'name'}
-        child_pane = self._panes.get(backend, Pane)(state, **kwargs)
+        pane_type = self._panes.get(backend, Pane)
+        if 'tight' in pane_type.param:
+            kwargs['tight'] = True
+        child_pane = pane_type(state, **kwargs)
         self._update_plot(plot, child_pane)
         model = child_pane._get_model(doc, root, parent, comm)
         if ref in self._plots:

panel/pane/plot.py

@@ -216,11 +216,6 @@ def _update(self, ref=None, model=None):
             manager.canvas.handle_resize(event)
         manager.canvas.draw_idle()
 
-    def _imgshape(self, data):
-        """Calculate and return image width,height"""
-        w, h = self.object.get_size_inches()
-        return int(w*72), int(h*72)
-
     def _data(self):
         self.object.set_dpi(self.dpi)
         b = BytesIO()