WIP, ENH: Button to change the background color

mne/viz/_brain/_brain.py

@@ -1368,9 +1368,16 @@ def _save_image(fname, img):
                 callback=partial(_save_image, img=img)
             )
 
+    def _set_background(self, val):
+        self.plotter.background_color = val
+
     def _configure_tool_bar(self):
         self._renderer._tool_bar_load_icons()
         self._renderer._tool_bar_initialize()
+        self._renderer._tool_bar_add_color_picker(
+            name="background",
+            func=self._set_background,
+        )
         self._renderer._tool_bar_add_button(
             name="screenshot",
             desc="Take a screenshot",

mne/viz/backends/_abstract.py

@@ -464,6 +464,10 @@ def _tool_bar_add_button(self, name, desc, func, icon_name=None):
     def _tool_bar_update_button_icon(self, name, icon_name):
         pass
 
+    @abstractmethod
+    def _tool_bar_add_color_picker(self, name, func):
+        pass
+
     @abstractmethod
     def _tool_bar_add_text(self, name, value, placeholder):
         pass

mne/viz/backends/_notebook.py

@@ -141,6 +141,9 @@ def _tool_bar_add_button(self, name, desc, func, icon_name=None):
         _ipy_add_widget(self.tool_bar, widget)
         self.actions[name] = widget
 
+    def _tool_bar_add_color_picker(self, name, func):
+        pass
+
     def _tool_bar_update_button_icon(self, name, icon_name):
         self.actions[name].icon = self.icons[icon_name]
 

mne/viz/backends/_qt.py

@@ -7,15 +7,16 @@
 
 from contextlib import contextmanager
 
+import numpy as np
 import pyvista
 
 from PyQt5.QtCore import Qt, pyqtSignal
-from PyQt5.QtGui import QIcon
+from PyQt5.QtGui import QIcon, QColor
 from PyQt5.QtWidgets import (QComboBox, QDockWidget, QDoubleSpinBox, QGroupBox,
-                             QHBoxLayout, QLabel, QToolButton,
+                             QHBoxLayout, QLabel, QPushButton, QToolButton,
                              QSlider, QSpinBox, QVBoxLayout, QWidget,
                              QSizePolicy, QScrollArea, QStyle,
-                             QStyleOptionSlider)
+                             QStyleOptionSlider, QColorDialog)
 
 from ._pyvista import _PyVistaRenderer
 from ._pyvista import (_close_all, _close_3d_figure, _check_3d_figure,  # noqa: F401,E501 analysis:ignore
@@ -135,6 +136,45 @@ def _dock_add_group_box(self, name, layout=None):
         return hlayout
 
 
+# from https://github.com/GuillaumeFavelier/blockbuilder
+class QColorButton(QPushButton):
+    """Select a color interactively."""
+
+    colorChanged = pyqtSignal(list)
+
+    def __init__(self, parent=None):
+        """Initialize the ColorButton."""
+        super().__init__(parent=parent)
+        self.color_dialog = QColorDialog(self)
+        self.clicked.connect(self.color_dialog.show)
+        self.setObjectName("ColorButton")
+        self.color_dialog.colorSelected.connect(self.setColor)
+
+    def _rgb2str(self, color, is_int=False):
+        if not is_int:
+            color = np.asarray(color) * 255
+            color = color.astype(np.uint8)
+        return str(tuple(color))
+
+    def _qrgb2rgb(self, color):
+        return (
+            color.red(),
+            color.green(),
+            color.blue()
+        )
+
+    def setColor(self, color, is_int=True):
+        """Set the current button color."""
+        if isinstance(color, QColor):
+            color = self._qrgb2rgb(color)
+        color = np.asarray(color)
+        self.setStyleSheet(
+            "#ColorButton{background-color: rgb" +
+            self._rgb2str(color, is_int) + "}")
+        if is_int:
+            self.colorChanged.emit(list(color / 255.))
+
+
 class QFloatSlider(QSlider):
     """Slider that handles float values."""
 
@@ -236,6 +276,12 @@ def _tool_bar_add_button(self, name, desc, func, icon_name=None):
         icon = self.icons[icon_name]
         self.actions[name] = self.tool_bar.addAction(icon, desc, func)
 
+    def _tool_bar_add_color_picker(self, name, func):
+        widget = QColorButton()
+        widget.colorChanged.connect(func)
+        self.tool_bar.addWidget(widget)
+        self.actions[name] = widget
+
     def _tool_bar_update_button_icon(self, name, icon_name):
         self.actions[name].setIcon(self.icons[icon_name])