BUG: Fix concat on Windows

mne/viz/_brain/_brain.py

@@ -1229,7 +1229,7 @@ def _configure_picking(self):
     def _configure_tool_bar(self):
         self._renderer._tool_bar_load_icons()
         self._renderer._tool_bar_set_theme(self.theme)
-        self._renderer._tool_bar_initialize()
+        self._renderer._tool_bar_initialize(name="Toolbar")
         self._renderer._tool_bar_add_file_button(
             name="screenshot",
             desc="Take a screenshot",
@@ -2611,9 +2611,11 @@ def screenshot(self, mode='rgb', time_viewer=False):
             Image pixel values.
         """
         img = self._renderer.screenshot(mode)
+        logger.debug(f'Got screenshot of size {img.shape}')
         if time_viewer and self.time_viewer and \
                 self.show_traces and \
                 not self.separate_canvas:
+            from matplotlib.image import imread
             canvas = self.mpl_canvas.fig.canvas
             canvas.draw_idle()
             fig = self.mpl_canvas.fig
@@ -2624,15 +2626,26 @@ def screenshot(self, mode='rgb', time_viewer=False):
                 # (e.g., macOS w/Qt 5.14+ and VTK9) then things won't work,
                 # so let's just calculate the DPI we need to get
                 # the correct size output based on the widths being equal
-                dpi = img.shape[1] / fig.get_size_inches()[0]
-                fig.savefig(output, dpi=dpi, format='raw',
+                size_in = fig.get_size_inches()
+                dpi = fig.get_dpi()
+                want_size = tuple(x * dpi for x in size_in)
+                n_pix = want_size[0] * want_size[1]
+                logger.debug(
+                    f'Saving figure of size {size_in} @ {dpi} DPI '
+                    f'({want_size} = {n_pix} pixels)')
+                # Sometimes there can be off-by-one errors here (e.g.,
+                # if in mpl int() rather than int(round()) is used to
+                # compute the number of pixels) so rather than use "raw"
+                # format and try to reshape ourselves, just write to PNG
+                # and read it, which has the dimensions encoded for us.
+                fig.savefig(output, dpi=dpi, format='png',
                             facecolor=self._bg_color, edgecolor='none')
                 output.seek(0)
-                trace_img = np.reshape(
-                    np.frombuffer(output.getvalue(), dtype=np.uint8),
-                    newshape=(-1, img.shape[1], 4))[:, :, :3]
-            img = concatenate_images(
-                [img, trace_img], bgcolor=self._brain_color[:3])
+                trace_img = imread(output, format='png')[:, :, :3]
+                trace_img = np.clip(
+                    np.round(trace_img * 255), 0, 255).astype(np.uint8)
+            bgcolor = np.array(self._brain_color[:3]) / 255
+            img = concatenate_images([img, trace_img], bgcolor=bgcolor)
         return img
 
     @contextlib.contextmanager

mne/viz/backends/_qt.py

@@ -391,7 +391,7 @@ def _window_get_mplcanvas(self, brain, interactor_fraction, show_traces,
 
     def _window_adjust_mplcanvas_layout(self):
         canvas = self._mplcanvas.canvas
-        dock, dock_layout = _create_dock_widget(
+        self._mpl_dock, dock_layout = _create_dock_widget(
             self._window, "Traces", Qt.BottomDockWidgetArea)
         dock_layout.addWidget(canvas)
 
@@ -414,10 +414,14 @@ def _window_ensure_minimum_sizes(self):
         # plotter.frame:      QFrame with QVBoxLayout with plotter.interactor as centralWidget  # noqa
         # plotter.ren_win:    vtkXOpenGLRenderWindow
         self._interactor.setMinimumSize(*sz)
+        # Lines like this are useful for debugging these issues:
+        # print('*' * 80)
+        # print(0, self._interactor.app_window.size().height(), self._interactor.size().height(), self._mpl_dock.widget().height(), self._mplcanvas.canvas.size().height())  # noqa
         if adjust_mpl:
             mpl_h = int(round((sz[1] * self._interactor_fraction) /
                               (1 - self._interactor_fraction)))
             self._mplcanvas.canvas.setMinimumSize(sz[0], mpl_h)
+            self._mpl_dock.widget().setMinimumSize(sz[0], mpl_h)
         try:
             yield  # show
         finally:
@@ -431,11 +435,17 @@ def _window_ensure_minimum_sizes(self):
             self._interactor.setMinimumSize(0, 0)
             if adjust_mpl:
                 self._mplcanvas.canvas.setMinimumSize(0, 0)
+                self._mpl_dock.widget().setMinimumSize(0, 0)
             self._process_events()
             self._process_events()
-            # 4. Resize the window and interactor to the correct size
+            # 4. Compute the extra height required for dock decorations and add
+            win_h = win_sz.height()
+            if adjust_mpl:
+                win_h += max(
+                    self._mpl_dock.widget().size().height() - mpl_h, 0)
+            # 5. Resize the window and interactor to the correct size
             #    (not sure why, but this is required on macOS at least)
-            self._interactor.window_size = (win_sz.width(), win_sz.height())
+            self._interactor.window_size = (win_sz.width(), win_h)
             self._interactor.resize(ren_sz.width(), ren_sz.height())
             self._process_events()
             self._process_events()
@@ -513,9 +523,12 @@ def show(self):
 
 
 def _create_dock_widget(window, name, area):
-    dock = QDockWidget()
+    # create dock widget
+    dock = QDockWidget(name)
+    # add scroll area
     scroll = QScrollArea(dock)
     dock.setWidget(scroll)
+    # give the scroll area a child widget
     widget = QWidget(scroll)
     scroll.setWidget(widget)
     scroll.setWidgetResizable(True)