vtkBalloonWidget

Section: Visualization Toolkit Widget Classes

Usage

The vtkBalloonWidget is used to popup text and/or an image when the mouse hovers over an instance of vtkProp. The widget keeps track of (vtkProp,vtkBalloon) pairs (where the internal vtkBalloon class is defined by a pair of vtkStdString and vtkImageData), and when the mouse stops moving for a user-specified period of time over the vtkProp, then the vtkBalloon is drawn nearby the vtkProp. Note that an instance of vtkBalloonRepresentation is used to draw the balloon. To use this widget, specify an instance of vtkBalloonWidget and a representation (e.g., vtkBalloonRepresentation). Then list all instances of vtkProp, a text string, and/or an instance of vtkImageData to be associated with each vtkProp. (Note that you can specify both text and an image, or just one or the other.) You may also wish to specify the hover delay (i.e., set in the superclass vtkHoverWidget).

.SECTION Event Bindings By default, the widget observes the following VTK events (i.e., it watches the vtkRenderWindowInteractor for these events): <pre> MouseMoveEvent - occurs when mouse is moved in render window. TimerEvent - occurs when the time between events (e.g., mouse move) is greater than TimerDuration. KeyPressEvent - when the "Enter" key is pressed after the balloon appears, a callback is activited (e.g., WidgetActivateEvent). </pre>

Note that the event bindings described above can be changed using this class's vtkWidgetEventTranslator. This class translates VTK events into the vtkBalloonWidget's widget events: <pre> vtkWidgetEvent::Move -- start the timer vtkWidgetEvent::TimedOut -- when hovering occurs, vtkWidgetEvent::SelectAction -- activate any callbacks associated with the balloon. </pre>

This widget invokes the following VTK events on itself (which observers can listen for): <pre> vtkCommand::TimerEvent (when hovering is determined to occur) vtkCommand::EndInteractionEvent (after a hover has occured and the mouse begins moving again). vtkCommand::WidgetActivateEvent (when the balloon is selected with a keypress). </pre>

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

  obj = vtkBalloonWidget

Methods

The class vtkBalloonWidget 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 vtkBalloonWidget class.