Allow style sheets to be used

MANIFEST.in

@@ -1,5 +1,6 @@
 include LICENSE
 include README.md
+recursive-include * *.mplstyle
 
 recursive-exclude * __pycache__
 recursive-exclude * *.py[co]

docs/guide/third_party.rst

@@ -32,7 +32,6 @@ The following properties and methods are useful for working with the figure and
 
 - `~.BaseNapariMPLWidget.figure` provides access to the figure
 - :meth:`~.BaseNapariMPLWidget.add_single_axes` adds a single axes to the figure, which can be accessed using the ``.axes`` attribute.
-- :meth:`~.BaseNapariMPLWidget.apply_napari_colorscheme` can be used to apply the napari colorscheme to any Axes you setup manually on the figure.
 
 Working with napari layers
 --------------------------

src/napari_matplotlib/base.py

@@ -2,8 +2,8 @@
 from pathlib import Path
 from typing import List, Optional, Tuple
 
+import matplotlib.style as mplstyle
 import napari
-from matplotlib.axes import Axes
 from matplotlib.backends.backend_qtagg import (
     FigureCanvas,
     NavigationToolbar2QT,
@@ -40,8 +40,11 @@ def __init__(
     ):
         super().__init__(parent=parent)
         self.viewer = napari_viewer
+        self._mpl_style_sheet_path: Optional[Path] = None
 
-        self.canvas = FigureCanvas()
+        # Sets figure.* style
+        with mplstyle.context(self.mpl_style_sheet_path):
+            self.canvas = FigureCanvas()
 
         self.canvas.figure.patch.set_facecolor("none")
         self.canvas.figure.set_layout_engine("constrained")
@@ -52,7 +55,7 @@ def __init__(
         # callback to update when napari theme changed
         # TODO: this isn't working completely (see issue #140)
         # most of our styling respects the theme change but not all
-        self.viewer.events.theme.connect(self._on_theme_change)
+        self.viewer.events.theme.connect(self._on_napari_theme_changed)
 
         self.setLayout(QVBoxLayout())
         self.layout().addWidget(self.toolbar)
@@ -63,47 +66,40 @@ def figure(self) -> Figure:
         """Matplotlib figure."""
         return self.canvas.figure
 
+    @property
+    def mpl_style_sheet_path(self) -> Path:
+        """
+        Path to the set Matplotlib style sheet.
+        """
+        if self._mpl_style_sheet_path is not None:
+            return self._mpl_style_sheet_path
+        elif self._napari_theme_has_light_bg():
+            return Path(__file__).parent / "styles" / "light.mplstyle"
+        else:
+            return Path(__file__).parent / "styles" / "dark.mplstyle"
+
+    @mpl_style_sheet_path.setter
+    def mpl_style_sheet_path(self, path: Path) -> None:
+        self._mpl_style_sheet_path = Path(path)
+
     def add_single_axes(self) -> None:
         """
         Add a single Axes to the figure.
 
         The Axes is saved on the ``.axes`` attribute for later access.
         """
-        self.axes = self.figure.subplots()
-        self.apply_napari_colorscheme(self.axes)
+        # Sets axes.* style.
+        # Does not set any text styling set by axes.* keys
+        with mplstyle.context(self.mpl_style_sheet_path):
+            self.axes = self.figure.subplots()
 
-    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
-        text_colour = theme.text.as_hex()  # text is high contrast to bg
-
-        # changing color of axes background to transparent
-        ax.set_facecolor("none")
-
-        # changing colors of all axes
-        for spine in ax.spines:
-            ax.spines[spine].set_color(fg_colour)
-
-        ax.xaxis.label.set_color(text_colour)
-        ax.yaxis.label.set_color(text_colour)
-
-        # changing colors of axes labels
-        ax.tick_params(axis="x", colors=text_colour)
-        ax.tick_params(axis="y", colors=text_colour)
-
-    def _on_theme_change(self) -> None:
-        """Update MPL toolbar and axis styling when `napari.Viewer.theme` is changed.
-
-        Note:
-            At the moment we only handle the default 'light' and 'dark' napari themes.
+    def _on_napari_theme_changed(self) -> None:
+        """
+        Called when the napari theme is changed.
         """
         self._replace_toolbar_icons()
-        if self.figure.gca():
-            self.apply_napari_colorscheme(self.figure.gca())
 
-    def _theme_has_light_bg(self) -> bool:
+    def _napari_theme_has_light_bg(self) -> bool:
         """
         Does this theme have a light background?
 
@@ -124,7 +120,7 @@ def _get_path_to_icon(self) -> Path:
         https://github.com/matplotlib/matplotlib/tree/main/lib/matplotlib/mpl-data/images
         """
         icon_root = Path(__file__).parent / "icons"
-        if self._theme_has_light_bg():
+        if self._napari_theme_has_light_bg():
             return icon_root / "black"
         else:
             return icon_root / "white"
@@ -211,6 +207,16 @@ def current_z(self) -> int:
         """
         return self.viewer.dims.current_step[0]
 
+    def _on_napari_theme_changed(self) -> None:
+        """Update MPL toolbar and axis styling when `napari.Viewer.theme` is changed.
+
+        Note:
+            At the moment we only handle the default 'light' and 'dark' napari themes.
+        """
+        super()._on_napari_theme_changed()
+        self.clear()
+        self.draw()
+
     def _setup_callbacks(self) -> None:
         """
         Sets up callbacks.
@@ -240,12 +246,14 @@ def _draw(self) -> None:
         Clear current figure, check selected layers are correct, and draw new
         figure if so.
         """
-        self.clear()
+        # Clearing axes sets new defaults, so need to make sure style is applied when
+        # this happens
+        with mplstyle.context(self.mpl_style_sheet_path):
+            self.clear()
         if self.n_selected_layers in self.n_layers_input and all(
             isinstance(layer, self.input_layer_types) for layer in self.layers
         ):
             self.draw()
-        self.apply_napari_colorscheme(self.figure.gca())
         self.canvas.draw()
 
     def clear(self) -> None:
@@ -288,7 +296,8 @@ def clear(self) -> None:
         """
         Clear the axes.
         """
-        self.axes.clear()
+        with mplstyle.context(self.mpl_style_sheet_path):
+            self.axes.clear()
 
 
 class NapariNavigationToolbar(NavigationToolbar2QT):

src/napari_matplotlib/scatter.py

@@ -23,6 +23,8 @@ def draw(self) -> None:
         """
         Scatter the currently selected layers.
         """
+        if len(self.layers) == 0:
+            return
         x, y, x_axis_name, y_axis_name = self._get_data()
 
         if x.size > self._threshold_to_switch_to_histogram:

src/napari_matplotlib/styles/README.md

@@ -0,0 +1,3 @@
+This folder contains default built-in Matplotlib style sheets.
+See https://matplotlib.org/stable/tutorials/introductory/customizing.html#defining-your-own-style
+for more info on Matplotlib style sheets.

src/napari_matplotlib/styles/dark.mplstyle

@@ -0,0 +1,12 @@
+# Dark-theme napari colour scheme for matplotlib plots
+
+# text (very light grey - almost white): #f0f1f2
+# foreground (mid grey):                 #414851
+# background (dark blue-gray):           #262930
+
+figure.facecolor    : none
+axes.labelcolor     : f0f1f2
+axes.facecolor      : none
+axes.edgecolor      : 414851
+xtick.color         : f0f1f2
+ytick.color         : f0f1f2

src/napari_matplotlib/styles/light.mplstyle

@@ -0,0 +1,12 @@
+# Light-theme napari colour scheme for matplotlib plots
+
+# text (very dark grey - almost black): #3b3a39
+# foreground (mid grey):                #d6d0ce
+# background (brownish beige):          #efebe9
+
+figure.facecolor    : none
+axes.labelcolor     : 3b3a39
+axes.facecolor      : none
+axes.edgecolor      : d6d0ce
+xtick.color         : 3b3a39
+ytick.color         : 3b3a39

src/napari_matplotlib/tests/conftest.py

@@ -1,4 +1,5 @@
 import os
+from pathlib import Path
 
 import numpy as np
 import pytest
@@ -52,3 +53,8 @@ def set_strict_qt():
         os.environ[env_var] = old_val
     else:
         del os.environ[env_var]
+
+
+@pytest.fixture
+def theme_path():
+    return Path(__file__).parent / "data" / "test_theme.mplstyle"

src/napari_matplotlib/tests/data/test_theme.mplstyle

@@ -0,0 +1,15 @@
+# Dark-theme napari colour scheme for matplotlib plots
+
+#f4b8b2 # light red
+#b2e4f4 # light blue
+#0aa3fc # dark blue
+#008939 # dark green
+
+figure.facecolor    : f4b8b2 # light red
+axes.facecolor      : b2e4f4 # light blue
+axes.edgecolor      : 0aa3fc # dark blue
+
+xtick.color         : 008939 # dark green
+xtick.labelcolor    : 008939 # dark green
+ytick.color         : 008939 # dark green
+ytick.labelcolor    : 008939 # dark green

src/napari_matplotlib/tests/test_theme.py

@@ -1,3 +1,5 @@
+from copy import deepcopy
+
 import napari
 import numpy as np
 import pytest
@@ -43,14 +45,14 @@ def test_theme_background_check(make_napari_viewer):
     widget = NapariMPLWidget(viewer)
 
     viewer.theme = "dark"
-    assert widget._theme_has_light_bg() is False
+    assert widget._napari_theme_has_light_bg() is False
 
     viewer.theme = "light"
-    assert widget._theme_has_light_bg() is True
+    assert widget._napari_theme_has_light_bg() is True
 
     _mock_up_theme()
     viewer.theme = "blue"
-    assert widget._theme_has_light_bg() is True
+    assert widget._napari_theme_has_light_bg() is True
 
 
 @pytest.mark.parametrize(
@@ -118,3 +120,23 @@ def test_no_theme_side_effects(make_napari_viewer):
     unrelated_figure.tight_layout()
 
     return unrelated_figure
+
+
+@pytest.mark.mpl_image_compare
+def test_custom_theme(make_napari_viewer, theme_path, brain_data):
+    viewer = make_napari_viewer()
+    viewer.theme = "dark"
+
+    widget = ScatterWidget(viewer)
+    widget.mpl_style_sheet_path = theme_path
+
+    viewer.add_image(brain_data[0], **brain_data[1], name="brain")
+    viewer.add_image(
+        brain_data[0] * -1, **brain_data[1], name="brain_reversed"
+    )
+
+    viewer.layers.selection.clear()
+    viewer.layers.selection.add(viewer.layers[0])
+    viewer.layers.selection.add(viewer.layers[1])
+
+    return deepcopy(widget.figure)