feat: Add rotation center selection

Author: AlejandroFernandezLuces

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

@@ -48,6 +48,7 @@
     ViewButton,
     ViewDirection,
 )
+from ansys.tools.visualization_interface.backends.pyvista.widgets.pick_rotation_center import PickRotCenterButton
 from ansys.tools.visualization_interface.backends.pyvista.widgets.widget import PlotterWidget
 from ansys.tools.visualization_interface.types.edge_plot import EdgePlot
 from ansys.tools.visualization_interface.types.mesh_object_plot import MeshObjectPlot
@@ -207,6 +208,7 @@ def enable_widgets(self, dark_mode: bool = False) -> None:
             if not self._use_qt:
                 self._widgets.append(MeshSliderWidget(self, dark_mode))
             self._widgets.append(HideButton(self, dark_mode))
+            self._widgets.append(PickRotCenterButton(self, dark_mode))
 
     def add_widget(self, widget: Union[PlotterWidget, List[PlotterWidget]]):
         """Add one or more custom widgets to the plotter.
@@ -363,6 +365,21 @@ def hover_callback(self, _widget, event_name) -> None:
             for label in self._added_hover_labels:
                 self._pl.scene.remove_actor(label)
 
+    def focus_point_selection(self, actor: "pv.Actor") -> None:
+        """Focus the camera on a selected actor.
+
+        Parameters
+        ----------
+        actor : ~pyvista.Actor
+            Actor to focus the camera on.
+
+        """
+        pt = self._pl.scene.picked_point
+        sphere = pv.Sphere(center=pt, radius=0.1)
+        self._pl.scene.add_mesh(sphere, color="red", name="focus_sphere_temp", reset_camera=False)
+        self._pl.scene.set_focus(pt)
+        self._pl.scene.render()
+
     def compute_edge_object_map(self) -> Dict[pv.Actor, EdgePlot]:
         """Compute the mapping between plotter actors and ``EdgePlot`` objects.
 
@@ -387,6 +404,16 @@ def enable_picking(self):
             show_message=False,
             picker="cell",
         )
+    
+    def enable_set_focus_center(self):
+        """Enable setting the focus of the camera to the picked point."""
+        self._pl.scene.enable_mesh_picking(
+            callback=self.focus_point_selection,
+            use_actor=True,
+            show=False,
+            show_message=False,
+            picker="cell",
+        )
 
     def enable_hover(self):
         """Enable hover capabilities in the plotter."""

src/ansys/tools/visualization_interface/backends/pyvista/widgets/_images/center_pick.png

@@ -0,0 +1,110 @@
+# Copyright (C) 2024 - 2025 ANSYS, Inc. and/or its affiliates.
+# SPDX-License-Identifier: MIT
+#
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+"""Provides the measure widget for the PyAnsys plotter."""
+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:
+    from ansys.tools.visualization_interface.backends.pyvista.pyvista import Plotter
+
+
+class PickRotCenterButton(PlotterWidget):
+    """Provides the pick rotation center widget for the Visualization Interface Tool ``Plotter`` class.
+
+    Parameters
+    ----------
+    plotter_helper : PlotterHelper
+        Plotter to add the pick rotation center widget to.
+    dark_mode : bool, optional
+        Whether to activate the dark mode or not.
+
+    """
+
+    def __init__(self, plotter_helper: "Plotter", dark_mode: bool = False) -> None:
+        """Initialize the ``PickRotCenterWidget`` class."""
+        # Call PlotterWidget ctor
+        super().__init__(plotter_helper._pl.scene)
+        self._dark_mode = dark_mode
+        # Initialize variables
+        self._actor: vtkActor = None
+        self.plotter_helper = plotter_helper
+        self._button: vtkButtonWidget = self.plotter_helper._pl.scene.add_checkbox_button_widget(
+            self.callback, position=(45, 10), size=30, border_size=3
+        )
+        self.update()
+
+    def callback(self, state: bool) -> None:
+        """Remove or add the pick rotation center widget actor upon click.
+
+        Parameters
+        ----------
+        state : bool
+            Whether the state of the button, which is inherited from PyVista, is active.
+
+        """
+        # This implementation uses direct calls to VTK due to limitations
+        # in PyVista. If there are improvements in the compatibility between
+        # the PyVista picker and the pick rotation center widget, this should be reviewed.
+
+        # Lazy import to avoid circular import
+        if not state:
+            self._text_actor.SetVisibility(0)
+            self.plotter_helper.scene.disable_picking()
+            if self.plotter_helper._allow_picking:
+                self.plotter_helper.enable_picking()
+            elif self.plotter_helper._allow_hovering:
+                self.plotter_helper.enable_hover()
+        else:
+            if self.plotter_helper._allow_picking:
+                self.plotter_helper.disable_picking()
+            elif self.plotter_helper._allow_hovering:
+                self.plotter_helper.disable_hover()
+            self.plotter_helper.enable_set_focus_center()
+            self._text_actor = self.plotter_helper.scene.add_text(
+                "Select a point to set the rotation center with right click",
+                position="upper_edge",   # options: 'upper_edge', 'lower_edge', 'left_edge', etc.
+                font_size=14,
+                color="grey",
+                shadow=True
+            )
+
+
+    def update(self) -> None:
+        """Define the measurement widget button parameters."""
+        if self._dark_mode:
+            is_inv = "_inv"
+        else:
+            is_inv = ""
+        show_measure_vr = self._button.GetRepresentation()
+        show_measure_icon_file = Path(
+            Path(__file__).parent / "_images" / f"center_pick{is_inv}.png"
+        )
+        show_measure_r = vtkPNGReader()
+        show_measure_r.SetFileName(show_measure_icon_file)
+        show_measure_r.Update()
+        image = show_measure_r.GetOutput()
+        show_measure_vr.SetButtonTexture(0, image)
+        show_measure_vr.SetButtonTexture(1, image)

src/ansys/tools/visualization_interface/backends/pyvista/widgets/_images/center_pick_inv.png

@@ -318,4 +318,29 @@ def test_slicing_tool():
     width, height = raw_plotter.window_size
 
     raw_plotter.iren._mouse_left_button_click(45, 60)
+    raw_plotter.close()
+
+def test_pick_rotation_center():
+    """Test pick rotation center tool interaction."""
+    pv_backend = PyVistaBackend()
+
+    pl = Plotter(backend=pv_backend)
+
+    # Create custom sphere
+    custom_sphere = CustomObject()
+    custom_sphere.mesh = pv.Sphere(center=(0, 0, 5))
+    custom_sphere.name = "CustomSphere"
+    mesh_object_sphere = MeshObjectPlot(custom_sphere, custom_sphere.get_mesh())
+
+    pl.plot(mesh_object_sphere)
+
+    # Run the plotter and simulate a click
+    pl.show(auto_close=False)
+
+    raw_plotter = pl.backend.scene
+    width, height = raw_plotter.window_size
+
+    raw_plotter.iren._mouse_left_button_click(45, 10)
+    raw_plotter.iren._mouse_right_button_press(width//2, height//2)
+    raw_plotter.iren._mouse_right_button_release(width//2, height//2)
     raw_plotter.close()