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vtkLineWidget2

Section: Visualization Toolkit Widget Classes

# Usage

This 3D widget defines a straight line that can be interactively placed in a scene. The widget is assumed to consist of two parts: 1) two end points and 2) a straight line connecting the two points. (The representation paired with this widget determines the actual geometry of the widget.) The positioning of the two end points is facilitated by using vtkHandleWidgets to position the points.

To use this widget, you generally pair it with a vtkLineRepresentation (or a subclass). Variuos options are available in the representation for controlling how the widget appears, and how the widget functions.

.SECTION Event Bindings By default, the widget responds to the following VTK events (i.e., it watches the vtkRenderWindowInteractor for these events):

     If one of the two end points are selected:
       LeftButtonPressEvent - activate the associated handle widget
       LeftButtonReleaseEvent - release the handle widget associated with the point
       MouseMoveEvent - move the point
     If the line is selected:
       LeftButtonPressEvent - activate a handle widget accociated with the line
       LeftButtonReleaseEvent - release the handle widget associated with the line
       MouseMoveEvent - translate the line
     In all the cases, independent of what is picked, the widget responds to the
     following VTK events:
       MiddleButtonPressEvent - translate the widget
       MiddleButtonReleaseEvent - release the widget
       RightButtonPressEvent - scale the widget's representation
       RightButtonReleaseEvent - stop scaling the widget
       MouseMoveEvent - scale (if right button) or move (if middle button) the widget

Note that the event bindings described above can be changed using this class's vtkWidgetEventTranslator. This class translates VTK events into the vtkLineWidget2's widget events:

       vtkWidgetEvent::Select – some part of the widget has been selected
       vtkWidgetEvent::EndSelect – the selection process has completed
       vtkWidgetEvent::Move – a request for slider motion has been invoked

In turn, when these widget events are processed, the vtkLineWidget2 invokes the following VTK events on itself (which observers can listen for):

       vtkCommand::StartInteractionEvent (on vtkWidgetEvent::Select)
       vtkCommand::EndInteractionEvent (on vtkWidgetEvent::EndSelect)
       vtkCommand::InteractionEvent (on vtkWidgetEvent::Move)

To create an instance of class vtkLineWidget2, simply invoke its constructor as follows

      obj = vtkLineWidget2

# Methods

The class vtkLineWidget2 has several methods that can be used. They are listed below. Note that the documentation is translated automatically from the VTK sources, and may not be completely intelligible. When in doubt, consult the VTK website. In the methods listed below, `obj` is an instance of the vtkLineWidget2 class.

- `string = obj.GetClassName ()` - Standard vtkObject methods
- `int = obj.IsA (string name)` - Standard vtkObject methods
- `vtkLineWidget2 = obj.NewInstance ()` - Standard vtkObject methods
- `vtkLineWidget2 = obj.SafeDownCast (vtkObject o)` - Standard vtkObject methods
- `obj.SetEnabled (int enabling)` - Override superclasses' SetEnabled() method because the line widget must enable its internal handle widgets.
- `obj.SetRepresentation (vtkLineRepresentation r)` - Create the default widget representation if one is not set.
- `obj.CreateDefaultRepresentation ()` - Create the default widget representation if one is not set.
- `obj.SetProcessEvents (int )` - Methods to change the whether the widget responds to interaction. Overridden to pass the state to component widgets.