text: /*=========================================================================
  
    Program:   Visualization Toolkit
    Module:    vtkButtonWidget.h
  
    Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
    All rights reserved.
    See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
  
       This software is distributed WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the above copyright notice for more information.
  
  =========================================================================*/
  /**
   * @class   vtkButtonWidget
   * @brief   activate an n-state button
   *
   * The vtkButtonWidget is used to interface with an n-state button. That is
   * each selection moves to the next button state (e.g., moves from "on" to
   * "off"). The widget uses modulo list traversal to transition through one or
   * more states. (A single state is simply a "selection" event; traversal
   * through the list can be in the forward or backward direction.)
   *
   * Depending on the nature of the representation the appearance of the button
   * can change dramatically, the specifics of appearance changes are a
   * function of the associated vtkButtonRepresentation (or subclass).
   *
   * @par Event Bindings:
   * By default, the widget responds to the following VTK events (i.e., it
   * watches the vtkRenderWindowInteractor for these events):
   * <pre>
   *   LeftButtonPressEvent - select button
   *   LeftButtonReleaseEvent - end the button selection process
   * </pre>
   *
   * @par Event Bindings:
   * Note that the event bindings described above can be changed using this
   * class's vtkWidgetEventTranslator. This class translates VTK events
   * into the vtkButtonWidget's widget events:
   * <pre>
   *   vtkWidgetEvent::Select -- some part of the widget has been selected
   *   vtkWidgetEvent::EndSelect -- the selection process has completed
   * </pre>
   *
   * @par Event Bindings:
   * In turn, when these widget events are processed, the vtkButtonWidget
   * invokes the following VTK events on itself (which observers can listen for):
   * <pre>
   *   vtkCommand::StateChangedEvent (on vtkWidgetEvent::EndSelect)
   * </pre>
   *
   */
  
  #ifndef vtkButtonWidget_h
  #define vtkButtonWidget_h
  
  #include "vtkAbstractWidget.h"
  #include "vtkInteractionWidgetsModule.h" // For export macro
  
  class vtkButtonRepresentation;
  
  class VTKINTERACTIONWIDGETS_EXPORT vtkButtonWidget : public vtkAbstractWidget
  {
  public:
    /**
     * Instantiate the class.
     */
    static vtkButtonWidget* New();
  
    //@{
    /**
     * Standard macros.
     */
    vtkTypeMacro(vtkButtonWidget, vtkAbstractWidget);
    void PrintSelf(ostream& os, vtkIndent indent) override;
    //@}
  
    /**
     * Specify an instance of vtkWidgetRepresentation used to represent this
     * widget in the scene. Note that the representation is a subclass of vtkProp
     * so it can be added to the renderer independent of the widget.
     */
    void SetRepresentation(vtkButtonRepresentation* r)
    {
      this->Superclass::SetWidgetRepresentation(reinterpret_cast<vtkWidgetRepresentation*>(r));
    }
  
    /**
     * Return the representation as a vtkButtonRepresentation.
     */
    vtkButtonRepresentation* GetSliderRepresentation()
    {
      return reinterpret_cast<vtkButtonRepresentation*>(this->WidgetRep);
    }
  
    /**
     * Create the default widget representation if one is not set.
     */
    void CreateDefaultRepresentation() override;
  
    /**
     * The method for activating and deactivating this widget. This method
     * must be overridden because it is a composite widget and does more than
     * its superclasses' vtkAbstractWidget::SetEnabled() method. The
     * method finds and sets the active viewport on the internal balloon
     * representation.
     */
    void SetEnabled(int) override;
  
  protected:
    vtkButtonWidget();
    ~vtkButtonWidget() override {}
  
    // These are the events that are handled
    static void SelectAction(vtkAbstractWidget*);
    static void MoveAction(vtkAbstractWidget*);
    static void EndSelectAction(vtkAbstractWidget*);
  
    // Manage the state of the widget
    int WidgetState;
    enum _WidgetState
    {
      Start = 0,
      Hovering,
      Selecting
    };
  
  private:
    vtkButtonWidget(const vtkButtonWidget&) = delete;
    void operator=(const vtkButtonWidget&) = delete;
  };
  
  #endif
  