feat: Refactor picker to allow custom callbacks

Author: AlejandroFernandezLuces

doc/source/user_guide/index.rst

@@ -108,3 +108,24 @@ class. After that, see these main use cases for customizing the plotter:
 
 Some practical examples of how to use the ``PlotterInterface`` class are included in some PyAnsys libraries,
 such as `PyAnsys Geometry <https://github.com/ansys/pyansys-geometry/pull/959>`_.
+
+
+Customizing the picker and hover callbacks
+==========================================
+
+The Visualization Interface Tool provides a base class, ``AbstractPicker``, for customizing the picker and hover
+callbacks of the plotter. This class provides a set of methods that can be overridden so that you can adapt the
+picker and hover functionalities to the specific need of your PyAnsys library.
+
+The first thing you must do is to create a class that inherits from the ``AbstractPicker`` class. After that, see 
+these main use cases for customizing the picker and hover callbacks:
+
+* You may want to change the way that objects are picked in the plotter. To do this, you can override the
+  ``pick_select_object`` and ``pick_unselect_object`` methods. These methods are called when an object is
+  selected or unselected, respectively.
+
+* Similarly, you may want to change the way that objects are hovered over in the plotter. To do this, you can
+  override the ``hover_select_object`` and ``hover_unselect_object`` methods. These methods are called when an
+  object is hovered over or unhovered, respectively.
+
+A practical example of how to use the ``AbstractPicker`` class are included in the examples section of the documentation.

examples/00-basic-pyvista-examples/custom_picker.py

@@ -0,0 +1,214 @@
+# 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.
+
+"""
+.. _ref_picker:
+
+===================
+Activate the picker
+===================
+
+This example shows how to create a custom picker. In this case we will show how the default
+picker is implemented through the ``AbstractPicker`` class.
+"""
+
+#####################################
+# Import the ``AbstractPicker`` class
+# ===================================
+
+# Import the abstract picker class
+from ansys.tools.visualization_interface.backends.pyvista.picker import AbstractPicker
+
+# Import custom object meshes
+from ansys.tools.visualization_interface.types.mesh_object_plot import MeshObjectPlot
+
+# Import plotter and color enum
+from ansys.tools.visualization_interface import Plotter
+from ansys.tools.visualization_interface.utils.color import Color
+
+
+#####################################
+# Create a custom picker class
+# =================================
+
+class CustomPicker(AbstractPicker):
+    def __init__(self, plotter_backend: "Plotter", plot_picked_names: bool = True) -> None:
+        """Initialize the ``Picker`` class."""
+        # Picking variables
+        self._plotter_backend = plotter_backend
+        self._plot_picked_names = plot_picked_names
+
+        # Map that relates PyVista actors with the added actors by the picker
+        self._picker_added_actors_map = {}
+
+        # Dictionary of picked objects in MeshObject format.
+        self._picked_dict = {}
+
+        # Map that saves original colors of the plotted objects.
+        self._origin_colors = {}
+
+        # Hovering variables
+        self._added_hover_labels = []
+
+    def pick_select_object(self, custom_object: MeshObjectPlot, pt: "np.ndarray") -> None:
+        """Add actor to picked list and add label if required.
+
+        Parameters
+        ----------
+        custom_object : MeshObjectPlot
+            The object to be selected.
+        pt : np.ndarray
+            The point where the object was picked.
+        """
+        added_actors = []
+
+        # Pick only custom objects
+        if isinstance(custom_object, MeshObjectPlot):
+            self._origin_colors[custom_object] = custom_object.actor.prop.color
+            custom_object.actor.prop.color = Color.PICKED.value
+
+        # Get the name for the text label
+        text = custom_object.name
+
+        # If picking names is enabled, add a label to the picked object
+        if self._plot_picked_names:
+            label_actor = self._plotter_backend.pv_interface.scene.add_point_labels(
+                [pt],
+                [text],
+                always_visible=True,
+                point_size=0,
+                render_points_as_spheres=False,
+                show_points=False,
+            )
+            # Add the label actor to the list of added actors
+            added_actors.append(label_actor)
+        
+        # Add the picked object to the picked dictionary if not already present, to keep track of it
+        if custom_object.name not in self._picked_dict:
+            self._picked_dict[custom_object.name] = custom_object
+        # Add the picked object to the picked dictionary if not already present, to keep track of it
+        self._picker_added_actors_map[custom_object.actor.name] = added_actors
+
+    def pick_unselect_object(self, custom_object: MeshObjectPlot) -> None:
+        """Remove actor from picked list and remove label if required.
+
+        Parameters
+        ----------
+        custom_object : MeshObjectPlot
+            The object to be unselected.
+        """
+        # remove actor from picked list and from scene
+        if custom_object.name in self._picked_dict:
+            self._picked_dict.pop(custom_object.name)
+
+        # Restore original color if it was changed
+        if isinstance(custom_object, MeshObjectPlot) and custom_object in self._origin_colors:
+            custom_object.actor.prop.color = self._origin_colors[custom_object]
+
+        # Remove any added actors (like labels) associated with this picked object
+        if custom_object.actor.name in self._picker_added_actors_map:
+            self._plotter_backend._pl.scene.remove_actor(self._picker_added_actors_map[custom_object.actor.name])
+            self._picker_added_actors_map.pop(custom_object.actor.name)
+
+    def hover_select_object(self, custom_object: MeshObjectPlot, actor: "Actor") -> None:
+        """Add label to hovered object if required.
+
+        Parameters
+        ----------
+        custom_object : MeshObjectPlot
+            The object to be hovered over.
+        actor : vtkActor
+            The actor corresponding to the hovered object.
+        """
+        for label in self._added_hover_labels:
+            self._plotter_backend._pl.scene.remove_actor(label)
+        label_actor = self._plotter_backend._pl.scene.add_point_labels(
+            [actor.GetCenter()],
+            [custom_object.name],
+            always_visible=True,
+            point_size=0,
+            render_points_as_spheres=False,
+            show_points=False,
+        )
+        self._added_hover_labels.append(label_actor)
+    
+    def hover_unselect_object(self):
+        """Remove all hover labels from the scene."""
+        for label in self._added_hover_labels:
+            self._plotter_backend._pl.scene.remove_actor(label)
+
+    @property
+    def picked_dict(self) -> dict:
+        """Return the dictionary of picked objects.
+        
+        Returns
+        -------
+        dict
+            Dictionary of picked objects.
+        """
+        return self._picked_dict
+
+#######################################################
+# Initialize the plotter backend with the custom picker
+# =====================================================
+
+from ansys.tools.visualization_interface.backends.pyvista import PyVistaBackend
+pl_backend = PyVistaBackend(allow_picking=True, custom_picker=CustomPicker)
+
+# Create the plotter with the custom backend
+pl = Plotter(backend=pl_backend)
+
+#################################################
+# Create a custom object with a name to be picked
+# ===============================================
+
+import pyvista as pv
+
+class CustomObject:
+    def __init__(self):
+        self.name = "CustomObject"
+        self.mesh = pv.Cube(center=(1, 1, 0))
+
+    def get_mesh(self):
+        return self.mesh
+
+    def name(self):
+        return self.name
+
+# Create a custom object
+custom_cube = CustomObject()
+custom_cube.name = "CustomCube"
+
+#########################################
+# Create a ``MeshObjectPlot`` instance
+# =======================================
+
+from ansys.tools.visualization_interface import MeshObjectPlot
+# Create an instance
+mesh_object_cube = MeshObjectPlot(custom_cube, custom_cube.get_mesh())
+
+##############################
+# Plot the custom object
+# ============================
+
+pl.plot(mesh_object_cube)
+pl.show()