BUG: Fix a few issues with the view function.

1. Improve handling Mayavi objects to be far more robust.
2. Fix an issue with using lists as default arguments. This would cause
   problems when view is called multiple times resulting in the last
   call rendering all the previous actors as well.

Author: prabhuramachandran

itkwidgets/widget_viewer.py

@@ -33,15 +33,12 @@
 
 have_mayavi = False
 try:
-    import mayavi.modules  # noqa: F401
+    from mayavi.core.pipeline_base import PipelineBase  # noqa: F401
     have_mayavi = True
 except ImportError:
     pass
 
 
-from IPython.core.debugger import set_trace
-
-
 def get_ioloop():
     import IPython
     import zmq
@@ -774,6 +771,25 @@ def roi_slice(self):
         return tuple(slices)
 
 
+def _process_mayavi_actors(objects):
+    from tvtk.api import tvtk
+    from mayavi.core.scene import Scene
+    from tvtk.pyface.tvtk_scene import TVTKScene
+    actors = []
+    for a in objects:
+        if isinstance(a, Scene) and a.scene is not None:
+            actors.extend([tvtk.to_vtk(x) for x in a.scene.renderer.actors])
+        elif isinstance(a, TVTKScene):
+            actors.extend([tvtk.to_vtk(x) for x in a.renderer.actors])
+        elif isinstance(a, PipelineBase):
+            actors.extend([tvtk.to_vtk(x) for x in a.actors])
+            if hasattr(a, 'actor'):
+                actors.extend([tvtk.to_vtk(x) for x in a.actor.actors])
+        else:
+            actors.append(a)
+    return actors
+
+
 def view(image=None,  # noqa: C901
          label_image=None,  # noqa: C901
          label_image_names=None,  # noqa: C901
@@ -785,11 +801,11 @@ def view(image=None,  # noqa: C901
          interpolation=True,
          gradient_opacity=0.22, opacity_gaussians=None, channels=None,
          slicing_planes=False, shadow=True, blend_mode='composite',
-         point_sets=[],
-         point_set_colors=[], point_set_opacities=[],
-         point_set_representations=[], point_set_sizes=[],
-         geometries=[],
-         geometry_colors=[], geometry_opacities=[],
+         point_sets=None,
+         point_set_colors=None, point_set_opacities=None,
+         point_set_representations=None, point_set_sizes=None,
+         geometries=None,
+         geometry_colors=None, geometry_opacities=None,
          ui_collapsed=False, rotate=False, annotations=True, axes=False, mode='v',
          **kwargs):
     """View the image and/or point sets and/or geometries.
@@ -991,6 +1007,23 @@ def view(image=None,  # noqa: C901
         widget.
     """
 
+    if point_sets is None:
+        point_sets = []
+    if point_set_colors is None:
+        point_set_colors = []
+    if point_set_opacities is None:
+        point_set_opacities = []
+    if point_set_representations is None:
+        point_set_representations = []
+    if point_set_sizes is None:
+        point_set_sizes = []
+    if geometries is None:
+        geometries = []
+    if geometry_colors is None:
+        geometry_colors = []
+    if geometry_opacities is None:
+        geometry_opacities = []
+
     # this block allows the user to pass already formed vtkActor vtkVolume
     # objects
     actors = kwargs.pop("actors", None)
@@ -1000,17 +1033,10 @@ def view(image=None,  # noqa: C901
             actors = [actors]
 
         images = []
+        if have_mayavi:
+            actors = _process_mayavi_actors(actors)
 
         for a in actors:
-            if have_mayavi:
-                from mayavi.modules import surface
-                from mayavi.modules import iso_surface
-                from tvtk.api import tvtk
-                if isinstance(a, surface.Surface):
-                    a = tvtk.to_vtk(a.actor.actor)
-                elif isinstance(a, iso_surface.IsoSurface):
-                    a = tvtk.to_vtk(a.actor.actor)
-
             if isinstance(a, vtk.vtkAssembly):  # unpack assemblies
                 cl = vtk.vtkPropCollection()
                 a.GetActors(cl)
@@ -1045,7 +1071,8 @@ def view(image=None,  # noqa: C901
                 tp.Update()
                 poly = tp.GetOutput()
                 prop = a.GetProperty()
-                if poly.GetNumberOfPolys() or poly.GetNumberOfStrips() or poly.GetNumberOfLines():
+                if (poly.GetNumberOfPolys() or poly.GetNumberOfStrips()
+                   or poly.GetNumberOfLines()):
                     geometries.insert(0, poly)
                     geometry_colors.insert(0, prop.GetColor())
                     geometry_opacities.insert(0, prop.GetOpacity())
@@ -1078,7 +1105,8 @@ def view(image=None,  # noqa: C901
                     point_set_opacities=point_set_opacities,
                     point_set_representations=point_set_representations,
                     point_set_sizes=point_set_sizes,
-                    geometries=geometries, geometry_colors=geometry_colors, geometry_opacities=geometry_opacities,
+                    geometries=geometries, geometry_colors=geometry_colors,
+                    geometry_opacities=geometry_opacities,
                     rotate=rotate, ui_collapsed=ui_collapsed,
                     annotations=annotations, axes=axes, mode=mode,
                     **kwargs)