Convert base64 in validate_coerce_fig_to_dict instead of validate_coerce

Converting to base64 in validate_coerce_fig_to_dict offers the same performance
improvements without changing the output of the data field of the Figure
object.

Author: marthacryan

packages/python/plotly/_plotly_utils/basevalidators.py

@@ -503,7 +503,7 @@ def validate_coerce(self, v):
         elif has_skipped_key(self.parent_name):
             v = to_scalar_or_list(v)
         elif is_homogeneous_array(v):
-            v = to_typed_array_spec(v)
+            v = copy_to_readonly_numpy_array(v)
         elif is_simple_array(v):
             v = to_scalar_or_list(v)
         else:

packages/python/plotly/plotly/io/_utils.py

@@ -1,3 +1,4 @@
+from _plotly_utils.basevalidators import is_homogeneous_array, to_typed_array_spec
 import plotly
 import plotly.graph_objs as go
 from plotly.offline import get_plotlyjs_version
@@ -24,6 +25,14 @@ def validate_coerce_fig_to_dict(fig, validate):
                 typ=type(fig), v=fig
             )
         )
+
+    # Add base64 conversion before sending to the front-end
+    for trace in fig_dict["data"]:
+        for key, value in trace.items():
+            if is_homogeneous_array(value):
+                print("to typed array: key:", key, "value:", value)
+                trace[key] = to_typed_array_spec(value)
+
     return fig_dict