MRG: Link cameras in _LinkViewer

mne/viz/_3d.py

@@ -1516,13 +1516,17 @@ def _plot_mpl_stc(stc, subject=None, surface='inflated', hemi='lh',
     return fig
 
 
-def link_brains(brains):
+def link_brains(brains, time=True, camera=False):
     """Plot multiple SourceEstimate objects with PyVista.
 
     Parameters
     ----------
     brains : list, tuple or np.ndarray
         The collection of brains to plot.
+    time : bool
+        If True, link the time controllers. Defaults to True.
+    camera : bool
+        If True, link the camera controls. Defaults to False.
     """
     from .backends.renderer import _get_3d_backend
     if _get_3d_backend() != 'pyvista':
@@ -1542,7 +1546,7 @@ def link_brains(brains):
             raise TypeError("Expected type is Brain but"
                             " {} was given.".format(type(brain)))
     # link brains properties
-    _LinkViewer(brains)
+    _LinkViewer(brains, time, camera)
 
 
 @verbose

mne/viz/_brain/_timeviewer.py

@@ -63,6 +63,7 @@ def __init__(self, time_viewer, width, height, dpi):
         # XXX eventually this should be called in the window resize callback
         tight_layout(fig=self.axes.figure)
         self.time_viewer = time_viewer
+        self.time_func = time_viewer.time_call
         for event in ('button_press', 'motion_notify'):
             self.canvas.mpl_connect(
                 event + '_event', getattr(self, 'on_' + event))
@@ -117,7 +118,7 @@ def on_button_press(self, event):
         if (event.inaxes != self.axes or
                 event.button != 1):
             return
-        self.time_viewer.time_call(
+        self.time_func(
             event.xdata, update_widget=True, time_as_index=False)
 
     on_motion_notify = on_button_press  # for now they can be the same
@@ -1199,28 +1200,48 @@ def clean(self):
 class _LinkViewer(object):
     """Class to link multiple _TimeViewer objects."""
 
-    def __init__(self, brains):
+    def __init__(self, brains, time=True, camera=False):
         self.brains = brains
         self.time_viewers = [brain.time_viewer for brain in brains]
 
-        # link time sliders
-        self.link_sliders(
-            name="_time_slider",
-            callback=self.set_time_point,
-            event_type="always"
-        )
+        # check time infos
+        times = [brain._times for brain in brains]
+        if time and not all(np.allclose(x, times[0]) for x in times):
+            warn('stc.times do not match, not linking time')
+            time = False
+
+        if camera:
+            self.link_cameras()
+
+        if time:
+            # link time sliders
+            self.link_sliders(
+                name="_time_slider",
+                callback=self.set_time_point,
+                event_type="always"
+            )
 
-        # link playback speed sliders
-        self.link_sliders(
-            name="_playback_speed_slider",
-            callback=self.set_playback_speed,
-            event_type="always"
-        )
+            # link playback speed sliders
+            self.link_sliders(
+                name="_playback_speed_slider",
+                callback=self.set_playback_speed,
+                event_type="always"
+            )
 
-        # link toggle to start/pause playback
-        for time_viewer in self.time_viewers:
-            time_viewer.actions["play"].triggered.disconnect()
-            time_viewer.actions["play"].triggered.connect(self.toggle_playback)
+            # link toggle to start/pause playback
+            for time_viewer in self.time_viewers:
+                time_viewer.actions["play"].triggered.disconnect()
+                time_viewer.actions["play"].triggered.connect(
+                    self.toggle_playback)
+
+            # link time course canvas
+            def _func(*args, **kwargs):
+                for time_viewer in self.time_viewers:
+                    time_viewer.time_call(*args, **kwargs)
+
+            for time_viewer in self.time_viewers:
+                if time_viewer.show_traces:
+                    time_viewer.mpl_canvas.time_func = _func
 
     def set_time_point(self, value):
         for time_viewer in self.time_viewers:
@@ -1231,8 +1252,8 @@ def set_playback_speed(self, value):
             time_viewer.playback_speed_call(value, update_widget=True)
 
     def toggle_playback(self):
-        master = self.time_viewers[0]  # select a master time_viewer
-        value = master.time_call.slider_rep.GetValue()
+        leader = self.time_viewers[0]  # select a time_viewer as leader
+        value = leader.time_call.slider_rep.GetValue()
         # synchronize starting points before playback
         self.set_time_point(value)
         for time_viewer in self.time_viewers:
@@ -1249,6 +1270,20 @@ def link_sliders(self, name, callback, event_type):
                     event_type=event_type
                 )
 
+    def link_cameras(self):
+        from ..backends._pyvista import _add_camera_callback
+
+        def _update_camera(vtk_picker, event):
+            for time_viewer in self.time_viewers:
+                time_viewer.plotter.update()
+
+        leader = self.time_viewers[0]  # select a time_viewer as leader
+        camera = leader.plotter.camera
+        _add_camera_callback(camera, _update_camera)
+        for time_viewer in self.time_viewers:
+            for renderer in time_viewer.plotter.renderers:
+                renderer.camera = camera
+
 
 def _get_range(brain):
     val = np.abs(brain._current_act_data)

mne/viz/_brain/tests/test_brain.py

@@ -279,7 +279,11 @@ def test_brain_linkviewer(renderer_interactive, travis_macos):
     brain_data = _create_testing_brain(hemi='split')
     _TimeViewer(brain_data)
 
-    link_viewer = _LinkViewer([brain_data])
+    link_viewer = _LinkViewer(
+        [brain_data],
+        time=True,
+        camera=True,
+    )
     link_viewer.set_time_point(value=0)
     link_viewer.set_playback_speed(value=0.1)
     link_viewer.toggle_playback()

mne/viz/backends/_pyvista.py

@@ -770,6 +770,10 @@ def _the_callback(widget, event):
     slider.AddObserver(event, _the_callback)
 
 
+def _add_camera_callback(camera, callback):
+    camera.AddObserver(vtk.vtkCommand.ModifiedEvent, callback)
+
+
 def _update_picking_callback(plotter,
                              on_mouse_move,
                              on_button_press,

mne/viz/tests/test_3d.py

@@ -836,7 +836,7 @@ def test_link_brains(renderer_interactive):
             link_brains([])
         with pytest.raises(TypeError, match='type is Brain'):
             link_brains('foo')
-        link_brains(brain)
+        link_brains(brain, time=True, camera=True)
 
 
 def test_renderer(renderer):