fix: Avoid importing VTK on startup

Author: AlejandroFernandezLuces

src/ansys/tools/visualization_interface/backends/pyvista/pyvista.py

@@ -26,9 +26,6 @@
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Union
 
 import pyvista as pv
-from vtkmodules.vtkCommonCore import vtkCommand
-from vtkmodules.vtkInteractionWidgets import vtkHoverWidget
-from vtkmodules.vtkRenderingCore import vtkPointPicker
 
 import ansys.tools.visualization_interface
 from ansys.tools.visualization_interface.backends._base import BaseBackend
@@ -110,6 +107,10 @@ def __init__(
         **plotter_kwargs,
     ) -> None:
         """Initialize the ``use_trame`` parameter and save the current ``pv.OFF_SCREEN`` value."""
+
+        from vtkmodules.vtkInteractionWidgets import vtkHoverWidget
+        from vtkmodules.vtkRenderingCore import vtkPointPicker
+
         # Check if the use of trame was requested
         if use_trame is None:
             use_trame = ansys.tools.visualization_interface.USE_TRAME
@@ -417,6 +418,10 @@ def enable_set_focus_center(self):
 
     def enable_hover(self):
         """Enable hover capabilities in the plotter."""
+
+        from vtkmodules.vtkCommonCore import vtkCommand
+        from vtkmodules.vtkInteractionWidgets import vtkHoverWidget
+
         self._hover_widget = vtkHoverWidget()
         self._hover_widget.SetInteractor(self._pl.scene.iren.interactor)
         self._hover_widget.SetTimerDuration(100)  # Time (ms) required to trigger a hover event

src/ansys/tools/visualization_interface/backends/pyvista/widgets/button.py

@@ -25,7 +25,6 @@
 from pathlib import Path
 
 from pyvista import Plotter
-from vtk import vtkButtonWidget, vtkPNGReader
 
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
@@ -49,6 +48,8 @@ class Button(PlotterWidget):
 
     def __init__(self, plotter: Plotter, button_config: tuple, dark_mode: bool = False) -> None:
         """Initialize the ``Button`` class."""
+        from vtk import vtkButtonWidget
+
         super().__init__(plotter)
         self._dark_mode = dark_mode
         self._button: vtkButtonWidget = self.plotter.add_checkbox_button_widget(
@@ -70,6 +71,8 @@ def callback(self, state: bool) -> None:
 
     def update(self) -> None:
         """Assign the image that represents the button."""
+        from vtk import vtkPNGReader
+
         if self._dark_mode:
             is_inv = "_inv"
         else:

src/ansys/tools/visualization_interface/backends/pyvista/widgets/hide_buttons.py

@@ -23,8 +23,6 @@
 from pathlib import Path
 from typing import TYPE_CHECKING
 
-from vtk import vtkActor, vtkButtonWidget, vtkPNGReader
-
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
 if TYPE_CHECKING:
@@ -45,6 +43,9 @@ class HideButton(PlotterWidget):
 
     def __init__(self, plotter: "Plotter", dark_mode: bool = False) -> None:
         """Initialize the ``HideButton`` class."""
+        from vtk import vtkActor, vtkButtonWidget
+
+
         # Call PlotterWidget ctor
         super().__init__(plotter._pl.scene)
         self._dark_mode = dark_mode
@@ -77,6 +78,8 @@ def callback(self, state: bool) -> None:
 
     def update(self) -> None:
         """Define the hide widget button parameters."""
+        from vtk import vtkPNGReader
+
         if self._dark_mode:
             is_inv = "_inv"
         else:

src/ansys/tools/visualization_interface/backends/pyvista/widgets/measure.py

@@ -23,8 +23,6 @@
 from pathlib import Path
 from typing import TYPE_CHECKING
 
-from vtk import vtkActor, vtkButtonWidget, vtkPNGReader
-
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
 if TYPE_CHECKING:
@@ -45,6 +43,8 @@ class MeasureWidget(PlotterWidget):
 
     def __init__(self, plotter_helper: "Plotter", dark_mode: bool = False) -> None:
         """Initialize the ``MeasureWidget`` class."""
+        from vtk import vtkActor, vtkButtonWidget
+
         # Call PlotterWidget ctor
         super().__init__(plotter_helper._pl.scene)
         self._dark_mode = dark_mode
@@ -88,6 +88,8 @@ def callback(self, state: bool) -> None:
                 self._widget = self.plotter_helper._pl.scene.add_measurement_widget()
 
     def update(self) -> None:
+        from vtk import vtkPNGReader
+
         """Define the measurement widget button parameters."""
         if self._dark_mode:
             is_inv = "_inv"

src/ansys/tools/visualization_interface/backends/pyvista/widgets/mesh_slider.py

@@ -24,7 +24,6 @@
 from typing import TYPE_CHECKING
 
 import pyvista as pv
-from vtk import vtkActor, vtkButtonWidget, vtkPNGReader
 
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
@@ -45,6 +44,8 @@ class MeshSliderWidget(PlotterWidget):
 
     def __init__(self, plotter_helper: "Plotter", dark_mode: bool = False) -> None:
         """Initialize the ``MeshSliderWidget`` class."""
+        from vtk import vtkActor, vtkButtonWidget
+
         # Call PlotterWidget ctor
         super().__init__(plotter_helper._pl.scene)
         self._dark_mode = dark_mode
@@ -103,6 +104,8 @@ def callback(self, state: bool) -> None:
 
     def update(self) -> None:
         """Define the mesh slider widget button parameters."""
+        from vtk import vtkPNGReader
+
         if self._dark_mode:
             is_inv = "_inv"
         else:

src/ansys/tools/visualization_interface/backends/pyvista/widgets/pick_rotation_center.py

@@ -23,7 +23,6 @@
 from pathlib import Path
 from typing import TYPE_CHECKING
 
-from vtk import vtkActor, vtkButtonWidget, vtkPNGReader
 
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
@@ -45,6 +44,7 @@ class PickRotCenterButton(PlotterWidget):
 
     def __init__(self, plotter_helper: "Plotter", dark_mode: bool = False) -> None:
         """Initialize the ``PickRotCenterWidget`` class."""
+        from vtk import vtkActor, vtkButtonWidget
         # Call PlotterWidget ctor
         super().__init__(plotter_helper._pl.scene)
         self._dark_mode = dark_mode
@@ -94,6 +94,8 @@ def callback(self, state: bool) -> None:
 
     def update(self) -> None:
         """Define the measurement widget button parameters."""
+        
+        from vtk import vtkPNGReader
         if self._dark_mode:
             is_inv = "_inv"
         else:

src/ansys/tools/visualization_interface/backends/pyvista/widgets/ruler.py

@@ -24,7 +24,6 @@
 from pathlib import Path
 
 from pyvista import Plotter
-from vtk import vtkActor, vtkButtonWidget, vtkPNGReader
 
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
@@ -43,6 +42,7 @@ class Ruler(PlotterWidget):
 
     def __init__(self, plotter: Plotter, dark_mode: bool = False) -> None:
         """Initialize the ``Ruler`` class."""
+        from vtk import vtkActor, vtkButtonWidget
         # Call PlotterWidget ctor
         super().__init__(plotter)
         self._dark_mode = dark_mode
@@ -85,6 +85,7 @@ def callback(self, state: bool) -> None:
 
     def update(self) -> None:
         """Define the configuration and representation of the ruler widget button."""
+        from vtk import vtkPNGReader
         if self._dark_mode:
             is_inv = "_inv"
         else:

src/ansys/tools/visualization_interface/backends/pyvista/widgets/screenshot.py

@@ -24,7 +24,6 @@
 from pathlib import Path
 
 from pyvista import Plotter
-from vtk import vtkActor, vtkButtonWidget, vtkPNGReader
 
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 
@@ -43,6 +42,7 @@ class ScreenshotButton(PlotterWidget):
 
     def __init__(self, plotter: Plotter, dark_mode: bool = False) -> None:
         """Initialize the ``ScreenshotButton`` class."""
+        from vtk import vtkActor, vtkButtonWidget
         # Call PlotterWidget ctor
         super().__init__(plotter)
         self._dark_mode = dark_mode
@@ -77,6 +77,7 @@ def callback(self, state: bool) -> None:
 
     def update(self) -> None:
         """Define the configuration and representation of the screenshot widget button."""
+        from vtk import vtkPNGReader
         if self._dark_mode:
             is_inv = "_inv"
         else: