Initial commit of SplineWidget.py

src/Python.md

@@ -657,6 +657,7 @@ See [this tutorial](http://www.vtk.org/Wiki/VTK/Tutorials/3DDataTypes) for a bri
 [OrientationMarkerWidget1](/Python/Widgets/OrientationMarkerWidget1) | Display a polydata as an orientation icon.
 [ScalarBarWidget](/Python/Widgets/ScalarBarWidget) | The ScalarBarWidget displays a scalar bar that is movable and changes orientation automatically when close to the borders of the image. It needs a ScalarBarActor
 [SphereWidget](/Python/Widgets/SphereWidget) | This 3D widget defines a sphere that can be interactively placed in a scene.
+[SplineWidget](/Python/Widgets/SplineWidget) | This example shows how to use vtkSplineWidget with a callback being used to get the length of the spline widget.
 [TextWidget](/Python/Widgets/TextWidget) | Annotate a VTK image with movable text
 
 ## Plotting

src/Python/Widgets/SplineWidget.md

+### Description
+
+This example shows how to use vtkSplineWidget with a callback being used to get the length of the spline widget.

src/Python/Widgets/SplineWidget.py

+#!/usr/bin/e
+
+# noinspection PyUnresolvedReferences
+import vtkmodules.vtkInteractionStyle
+# noinspection PyUnresolvedReferences
+import vtkmodules.vtkRenderingOpenGL2
+
+from vtkmodules.vtkCommonColor import vtkNamedColors
+from vtkmodules.vtkCommonCore import (
+    vtkCommand,
+    vtkVersion
+)
+from vtkmodules.vtkFiltersSources import vtkCylinderSource
+from vtkmodules.vtkInteractionStyle import vtkInteractorStyleTrackballCamera
+from vtkmodules.vtkInteractionWidgets import (
+    vtkCameraOrientationWidget,
+    vtkSplineWidget
+)
+from vtkmodules.vtkRenderingCore import (
+    vtkActor,
+    vtkPolyDataMapper,
+    vtkRenderWindow,
+    vtkRenderWindowInteractor,
+    vtkRenderer
+)
+
+
+def main(argv):
+    colors = vtkNamedColors()
+    colors.SetColor('ParaViewBkg', [82, 87, 110, 255])
+
+    has_cow = False
+    if vtk_version_ok(9, 0, 20210718):
+        cam_orient_manipulator = vtkCameraOrientationWidget()
+        has_cow = True
+
+    window_width = 1024
+    window_height = 1024
+
+    ren_win = vtkRenderWindow()
+    ren_win.SetSize(window_width, window_height)
+    iren = vtkRenderWindowInteractor()
+    iren.SetRenderWindow(ren_win)
+    style = vtkInteractorStyleTrackballCamera()
+    iren.SetInteractorStyle(style)
+
+    renderer = vtkRenderer()
+    renderer.SetBackground(colors.GetColor3d('ParaViewBkg'))
+
+    # Create a cylinder.
+    cylinder = vtkCylinderSource()
+    cylinder.SetCenter(0.0, 0.0, 0.0)
+    cylinder.SetRadius(3.0)
+    cylinder.SetHeight(5.0)
+    cylinder.SetResolution(100)
+
+    # Create a mapper and actor
+    mapper = vtkPolyDataMapper()
+    mapper.SetInputConnection(cylinder.GetOutputPort())
+    actor = vtkActor()
+    actor.GetProperty().SetColor(colors.GetColor3d('Cornsilk'))
+    actor.SetMapper(mapper)
+    # Add the actor to the scene
+    renderer.AddActor(actor)
+
+    ren_win.AddRenderer(renderer)
+
+    # A spline widget
+    spline_widget = vtkSplineWidget()
+    spline_widget.SetInteractor(iren)
+    spline_widget.SetProp3D(actor)
+    spline_widget.PlaceWidget(-2.5, 2.5, 3.5, 3.5, 0, 0, )
+    spline_widget.On()
+
+    spline_widget.AddObserver(vtkCommand.EndInteractionEvent, SplineCallback(spline_widget))
+    # Important: The interactor must be set prior to enabling the widget.
+    iren.SetRenderWindow(ren_win)
+
+    if has_cow:
+        cam_orient_manipulator.SetParentRenderer(renderer)
+        # Enable the widget.
+        cam_orient_manipulator.On()
+
+    ren_win.Render()
+    ren_win.SetWindowName('SplineWidget')
+    iren.Start()
+
+
+def vtk_version_ok(major, minor, build):
+    """
+    Check the VTK version.
+
+    :param major: Requested major version.
+    :param minor: Requested minor version.
+    :param build: Requested build version.
+    :return: True if the requested VTK version is >= the actual VTK version.
+    """
+    requested_version = (100 * int(major) + int(minor)) * 100000000 + int(build)
+    ver = vtkVersion()
+    actual_version = (100 * ver.GetVTKMajorVersion() + ver.GetVTKMinorVersion()) \
+                     * 100000000 + ver.GetVTKBuildVersion()
+    if actual_version >= requested_version:
+        return True
+    else:
+        return False
+
+
+class SplineCallback:
+    def __init__(self, spline_widget):
+        self.spline = spline_widget
+
+    def __call__(self, caller, ev):
+        spline_widget = caller
+        length = spline_widget.GetSummedLength()
+        print(f'Length: {length}')
+
+
+if __name__ == '__main__':
+    import sys
+
+    main(sys.argv)