Use light icons on dark themes for wx, too.

anntzer · anntzer · commit 03e0cb12ca93 · 2020-06-01T00:14:44.000+02:00
This can be tried e.g. by setting `GTK_THEME` to `Adwaita:dark`.
I made the `_icon` API "consistent" across qt and wx, too.
diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
@@ -703,6 +703,10 @@ def basedir(self):
         return str(cbook._get_data_path('images'))
 
     def _icon(self, name):
+        """
+        Construct a `.QIcon` from an image file *name*, including the extension
+        and relative to Matplotlib's "images" data directory.
+        """
         if QtCore.qVersion() >= '5.':
             name = name.replace('.png', '_large.png')
         pm = QtGui.QPixmap(str(cbook._get_data_path('images', name)))
diff --git a/lib/matplotlib/backends/backend_wx.py b/lib/matplotlib/backends/backend_wx.py
@@ -13,6 +13,9 @@
 import sys
 import weakref
 
+import numpy as np
+import PIL
+
 import matplotlib as mpl
 from matplotlib.backend_bases import (
     _Backend, FigureCanvasBase, FigureManagerBase, GraphicsContextBase,
@@ -1114,7 +1117,7 @@ def __init__(self, canvas):
             self.wx_ids[text] = (
                 self.AddTool(
                     -1,
-                    bitmap=_load_bitmap(f"{image_file}.png"),
+                    bitmap=self._icon(f"{image_file}.png"),
                     bmpDisabled=wx.NullBitmap,
                     label=text, shortHelp=text, longHelp=tooltip_text,
                     kind=(wx.ITEM_CHECK if text in ["Pan", "Zoom"]
@@ -1146,6 +1149,31 @@ def __init__(self, canvas):
     zoomStartX = cbook._deprecate_privatize_attribute("3.3")
     zoomStartY = cbook._deprecate_privatize_attribute("3.3")
 
+    @staticmethod
+    def _icon(name):
+        """
+        Construct a `wx.Bitmap` suitable for use as icon from an image file
+        *name*, including the extension and relative to Matplotlib's "images"
+        data directory.
+        """
+        image = np.array(PIL.Image.open(cbook._get_data_path("images", name)))
+        try:
+            dark = wx.SystemSettings.GetAppearance().IsDark()
+        except AttributeError:  # wxpython < 4.1
+            # copied from wx's IsUsingDarkBackground / GetLuminance.
+            bg = wx.SystemSettings.GetColour(wx.SYS_COLOUR_WINDOW)
+            fg = wx.SystemSettings.GetColour(wx.SYS_COLOUR_WINDOWTEXT)
+            # See wx.Colour.GetLuminance.
+            bg_lum = (.299 * bg.red + .587 * bg.green + .114 * bg.blue) / 255
+            fg_lum = (.299 * fg.red + .587 * fg.green + .114 * fg.blue) / 255
+            dark = fg_lum - bg_lum > .2
+        if dark:
+            fg = wx.SystemSettings.GetColour(wx.SYS_COLOUR_WINDOWTEXT)
+            black_mask = (image[..., :3] == 0).all(axis=-1)
+            image[black_mask, :3] = (fg.Red(), fg.Green(), fg.Blue())
+        return wx.Bitmap.FromBufferRGBA(
+            image.shape[1], image.shape[0], image.tobytes())
+
     def get_canvas(self, frame, fig):
         return type(self.canvas)(frame, -1, fig)
 
@@ -1375,7 +1403,7 @@ def add_toolitem(self, name, group, position, image_file, description,
             start = self._get_tool_pos(sep) + 1
         idx = start + position
         if image_file:
-            bmp = _load_bitmap(image_file)
+            bmp = NavigationToolbar2Wx._icon(image_file)
             kind = wx.ITEM_NORMAL if not toggle else wx.ITEM_CHECK
             tool = self.InsertTool(idx, -1, name, bmp, wx.NullBitmap, kind,
                                    description or "")
