Use matplotlib background colors when converting from matplotlib

plotly/matplotlylib/renderer.py

@@ -11,9 +11,16 @@
 
 import plotly.graph_objs as go
 from plotly.matplotlylib.mplexporter import Renderer
+from plotly.matplotlylib.mplexporter.utils import export_color
 from plotly.matplotlylib import mpltools
 
 
+def _export_background_color(color):
+    """Export a matplotlib patch facecolor for use as a plotly background color."""
+    bgcolor = export_color(color)
+    return "rgba(0,0,0,0)" if bgcolor == "none" else bgcolor
+
+
 class PlotlyRenderer(Renderer):
     """A renderer class inheriting from base for rendering mpl plots in plotly.
 
@@ -79,6 +86,9 @@ def open_figure(self, fig, props):
             autosize=False,
             hovermode="closest",
         )
+        self.plotly_fig["layout"].paper_bgcolor = _export_background_color(
+            fig.patch.get_facecolor()
+        )
         self.mpl_x_bounds, self.mpl_y_bounds = mpltools.get_axes_bounds(fig)
         margin = go.layout.Margin(
             l=int(self.mpl_x_bounds[0] * self.plotly_fig["layout"]["width"]),
@@ -144,6 +154,10 @@ def open_axes(self, ax, props):
         ]
         self.current_bars = []
         self.axis_ct += 1
+        # update plot background with the axes background from mpl
+        self.plotly_fig["layout"].plot_bgcolor = _export_background_color(
+            props["axesbg"]
+        )
         # set defaults in axes
         xaxis = go.layout.XAxis(
             anchor="y{0}".format(self.axis_ct), zeroline=False, ticks="inside"

plotly/matplotlylib/tests/test_renderer.py

@@ -84,3 +84,26 @@ def test_multiple_traces_native_legend():
     assert plotly_fig.data[0].mode == "lines"
     assert plotly_fig.data[1].mode == "markers"
     assert plotly_fig.data[2].mode == "lines+markers"
+
+
+
+def test_background_colors_from_matplotlib_defaults():
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1])
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.plot_bgcolor == "#FFFFFF"
+    assert plotly_fig.layout.paper_bgcolor == "#FFFFFF"
+
+
+def test_custom_background_colors_are_preserved():
+    fig, ax = plt.subplots()
+    fig.patch.set_facecolor("lightyellow")
+    ax.set_facecolor("lightgray")
+    ax.plot([0, 1], [0, 1])
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.plot_bgcolor == "#D3D3D3"
+    assert plotly_fig.layout.paper_bgcolor == "#FFFFE0"