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Usage
The vtkAngleWidget is used to measure the angle between two
rays (defined by three points). The three points (two end
points and a center) can be positioned independently, and
when they are released, a special PlacePointEvent is invoked
so that special operations may be take to reposition the
point (snap to grid, etc.) The widget has two different
modes of interaction: when initially defined (i.e., placing
the three points) and then a manipulate mode (adjusting the
position of the three points).
To use this widget, specify an instance of vtkAngleWidget
and a representation (a subclass of vtkAngleRepresentation).
The widget is implemented using three instances of
vtkHandleWidget which are used to position the three points.
The representations for these handle widgets are provided by
the vtkAngleRepresentation.
.SECTION Event Bindings By default, the widget responds to
the following VTK events (i.e., it watches the
vtkRenderWindowInteractor for these events):
LeftButtonPressEvent - add a point or select a handle
MouseMoveEvent - position the second or third point, or
move a handle
LeftButtonReleaseEvent - release the selected handle
Note that the event bindings described above can be changed
using this class's vtkWidgetEventTranslator. This class
translates VTK events into the vtkAngleWidget's widget
events:
vtkWidgetEvent::AddPoint – add one point;
depending on the state
it may the first, second or
third point
added. Or, if near a
handle, select the handle.
vtkWidgetEvent::Move – position the second or
third point, or move the
handle depending on the state.
vtkWidgetEvent::EndSelect – the handle
manipulation process has completed.
This widget invokes the following VTK events on itself
(which observers can listen for):
vtkCommand::StartInteractionEvent (beginning to
interact)
vtkCommand::EndInteractionEvent (completing
interaction)
vtkCommand::InteractionEvent (moving a handle)
vtkCommand::PlacePointEvent (after a point is
positioned;
call data includes handle
id (0,1,2))
To create an instance of class vtkAngleWidget, simply invoke
its constructor as follows
obj = vtkAngleWidget
Methods
The class vtkAngleWidget 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 vtkAngleWidget class.
* string = obj.GetClassName () - Standard methods for a VTK
class.
* int = obj.IsA (string name) - Standard methods for a VTK
class.
* vtkAngleWidget = obj.NewInstance () - Standard methods for
a VTK class.
* vtkAngleWidget = obj.SafeDownCast (vtkObject o) - Standard
methods for a VTK class.
* obj.SetEnabled (int ) - The method for activiating and
deactiviating this widget. This method must be overridden
because it is a composite widget and does more than its
superclasses' vtkAbstractWidget::SetEnabled() method.
* obj.SetRepresentation (vtkAngleRepresentation r) - Create
the default widget representation if one is not set.
* obj.CreateDefaultRepresentation () - Create the default
widget representation if one is not set.
* int = obj.IsAngleValid () - A flag indicates whether the
angle is valid. The angle value only becomes valid after
two of the three points are placed.
* obj.SetProcessEvents (int ) - Methods to change the
whether the widget responds to interaction. Overridden to
pass the state to component widgets.
* FreeMat_Documentation
* Visualization_Toolkit_Widget_Classes
* Generated on Thu Jul 25 2013 17:18:36 for FreeMat by
doxygen_ 1.8.1.1
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