matplotlib · samcunliffe · Jun 8, 2023 · Jun 8, 2023 · Jun 12, 2023 · Jun 15, 2023
diff --git a/src/napari_matplotlib/base.py b/src/napari_matplotlib/base.py
@@ -2,6 +2,7 @@
 from pathlib import Path
 from typing import List, Optional, Tuple
 
+import matplotlib.style
 import napari
 from matplotlib.axes import Axes
 from matplotlib.backends.backend_qtagg import (
@@ -41,9 +42,11 @@ def __init__(
         super().__init__(parent=parent)
         self.viewer = napari_viewer
 
+        has_mpl_stylesheet = self._apply_user_stylesheet_if_present()
         self.canvas = FigureCanvas()
 
-        self.canvas.figure.patch.set_facecolor("none")
+        if not has_mpl_stylesheet:
+            self.canvas.figure.patch.set_facecolor("none")
         self.canvas.figure.set_layout_engine("constrained")
         self.toolbar = NapariNavigationToolbar(
             self.canvas, parent=self
@@ -70,10 +73,16 @@ def add_single_axes(self) -> None:
         The Axes is saved on the ``.axes`` attribute for later access.
         """
         self.axes = self.figure.subplots()
-        self.apply_napari_colorscheme(self.axes)
+        self.apply_style(self.axes)
+
+    def apply_style(self, ax: Axes) -> None:
+        """
+        Use the user-supplied stylesheet if present, otherwise apply the
+        napari-compatible colorscheme (theme-dependent) to an Axes.
+        """
+        if self._apply_user_stylesheet_if_present():
+            return
 
-    def apply_napari_colorscheme(self, ax: Axes) -> None:
-        """Apply napari-compatible colorscheme to an Axes."""
         # get the foreground colours from current theme
         theme = napari.utils.theme.get_theme(self.viewer.theme, as_dict=False)
         fg_colour = theme.foreground.as_hex()  # fg is a muted contrast to bg
@@ -93,6 +102,20 @@ def apply_napari_colorscheme(self, ax: Axes) -> None:
         ax.tick_params(axis="x", colors=text_colour)
         ax.tick_params(axis="y", colors=text_colour)
 
+    def _apply_user_stylesheet_if_present(self) -> bool:
+        """
+        Apply the user-supplied stylesheet if present.
+
+        Returns
+        -------
+        True if the stylesheet was present and applied.
+        False otherwise.
+        """
+        if (Path.cwd() / "user.mplstyle").exists():
+            matplotlib.style.use("./user.mplstyle")
+            return True
+        return False
+
     def _on_theme_change(self) -> None:
         """Update MPL toolbar and axis styling when `napari.Viewer.theme` is changed.
 
@@ -101,7 +124,7 @@ def _on_theme_change(self) -> None:
         """
         self._replace_toolbar_icons()
         if self.figure.gca():
-            self.apply_napari_colorscheme(self.figure.gca())
+            self.apply_style(self.figure.gca())
 
     def _theme_has_light_bg(self) -> bool:
         """
@@ -245,7 +268,7 @@ def _draw(self) -> None:
             isinstance(layer, self.input_layer_types) for layer in self.layers
         ):
             self.draw()
-        self.apply_napari_colorscheme(self.figure.gca())
+        self.apply_style(self.figure.gca())
         self.canvas.draw()
 
     def clear(self) -> None:

diff --git a/src/napari_matplotlib/tests/test_theme.py b/src/napari_matplotlib/tests/test_theme.py
@@ -1,8 +1,13 @@
+import shutil
+from pathlib import Path
+
+import matplotlib
 import napari
 import numpy as np
 import pytest
+from matplotlib.colors import to_rgba
 
-from napari_matplotlib import ScatterWidget
+from napari_matplotlib import HistogramWidget, ScatterWidget
 from napari_matplotlib.base import NapariMPLWidget
 
 
@@ -91,7 +96,7 @@ def test_titles_respect_theme(
 
 
 @pytest.mark.mpl_image_compare
-def test_no_theme_side_effects(make_napari_viewer):
+def test_no_theme_side_effects(tmpdir, make_napari_viewer):
     """Ensure that napari-matplotlib doesn't pollute the globally set style.
 
     A MWE to guard aganst issue matplotlib/#64. Should always reproduce a plot
@@ -102,9 +107,11 @@ def test_no_theme_side_effects(make_napari_viewer):
     np.random.seed(12345)
 
     # should not affect global matplotlib plot style
-    viewer = make_napari_viewer()
-    viewer.theme = "dark"
-    NapariMPLWidget(viewer)
+    with tmpdir.as_cwd():
+        shutil.copy(find_mpl_stylesheet("Solarize_Light2"), "./user.mplstyle")
+        viewer = make_napari_viewer()
+        viewer.theme = "dark"
+        NapariMPLWidget(viewer)
 
     # some plotting unrelated to napari-matplotlib
     normal_dist = np.random.normal(size=1000)
@@ -118,3 +125,34 @@ def test_no_theme_side_effects(make_napari_viewer):
     unrelated_figure.tight_layout()
 
     return unrelated_figure
+
+
+def find_mpl_stylesheet(name: str) -> Path:
+    """Find the built-in matplotlib stylesheet."""
+    return Path(matplotlib.__path__[0]) / f"mpl-data/stylelib/{name}.mplstyle"
+
+
+def test_stylesheet_in_cwd(tmpdir, make_napari_viewer, image_data):
+    """
+    Test that a stylesheet in the current directory is given precidence.
+
+    Do this by copying over a stylesheet from matplotlib's built in styles,
+    naming it correctly, and checking the colours are as expected.
+    """
+    with tmpdir.as_cwd():
+        # Copy Solarize_Light2 to current dir as if it was a user-overriden stylesheet.
+        shutil.copy(find_mpl_stylesheet("Solarize_Light2"), "./user.mplstyle")
+        viewer = make_napari_viewer()
+        viewer.add_image(image_data[0], **image_data[1])
+        widget = HistogramWidget(viewer)
+        ax = widget.figure.gca()
+
+        # The axes should have a light brownish grey background:
+        assert ax.get_facecolor() == to_rgba("#eee8d5")
+        assert ax.patch.get_facecolor() == to_rgba("#eee8d5")
+
+        # The figure background and axis gridlines are light yellow:
+        assert widget.figure.patch.get_facecolor() == to_rgba("#fdf6e3")
+        for gridline in ax.get_xgridlines() + ax.get_ygridlines():
+            assert gridline.get_visible() is True
+            assert gridline.get_color() == "#fdf6e3"