SoHandleEventAction(3)

NAME
SoHandleEventAction - The SoHandleEventAction class distributes user events to the scene.

This is the action used by the GUI viewer classes to pass interaction events from the window system to the nodes in the scene graph.

SYNOPSIS

#include <Inventor/actions/SoHandleEventAction.h>

Inherits SoAction.

  Public Member Functions
virtual SoType getTypeId (void) const
SoHandleEventAction (const SbViewportRegion &viewportregion)
virtual ~SoHandleEventAction (void)
void setViewportRegion (const SbViewportRegion &newregion)
const SbViewportRegion & getViewportRegion (void) const
void setEvent (const SoEvent *ev)
const SoEvent * getEvent (void) const
void setHandled (void)
SbBool isHandled (void) const
void setGrabber (SoNode *node)
void releaseGrabber (void)
SoNode * getGrabber (void) const
void setPickRoot (SoNode *node)
SoNode * getPickRoot (void) const
void setPickRadius (const float radiusinpixels)
const SoPickedPoint * getPickedPoint (void)
const SoPickedPointList & getPickedPointList (void)

  Static Public Member Functions
static SoType getClassTypeId (void)
static void addMethod (const SoType type, SoActionMethod method)
static void enableElement (const SoType type, const int stackindex)
static void initClass (void)

  Protected Member Functions
virtual const SoEnabledElementsList & getEnabledElements (void) const
virtual void beginTraversal (SoNode *node)

  Static Protected Member Functions
static SoEnabledElementsList * getClassEnabledElements (void)
static SoActionMethodList * getClassActionMethods (void)

  Additional Inherited Members

Detailed Description

The SoHandleEventAction class distributes user events to the scene.

This is the action used by the GUI viewer classes to pass interaction events from the window system to the nodes in the scene graph. SoHandleEventAction also provides the functionality for tracking the object currently under the cursor, and functionality for 'grabbing' the event focus.

See also:
    SoEvent

Constructor & Destructor Documentation

  SoHandleEventAction::SoHandleEventAction (const SbViewportRegion & viewportregion)
Constructor.

SoHandleEventAction needs a viewportregion to pass on to the raypick action instance it uses for being able to track objects under the mouse cursor.

  SoHandleEventAction::~SoHandleEventAction (void) [virtual]
Destructor.

Member Function Documentation

  SoType SoHandleEventAction::getTypeId (void) const [virtual]
Returns the type identification of an action derived from a class inheriting SoAction. This is used for run-time type checking and 'downward' casting.

Usage example:

void bar(SoAction * action)
{
  if (action->getTypeId() == SoGLRenderAction::getClassTypeId()) {
    // safe downward cast, know the type
    SoGLRenderAction * glrender = (SoGLRenderAction *)action;
  }
  return; // ignore if not renderaction
}

For application programmers wanting to extend the library with new actions: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through Inventor/nodes/SoSubAction.h: SO_ACTION_SOURCE, SO_ACTION_INIT_CLASS and SO_ACTION_CONSTRUCTOR.

For more information on writing Coin extensions, see the SoAction class documentation.

Returns the actual type id of an object derived from a class inheriting SoAction. Needs to be overridden in all subclasses.

Implements SoAction.

  void SoHandleEventAction::addMethod (const SoType type, SoActionMethod method) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoHandleEventAction::enableElement (const SoType type, const int stackindex) [static]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  const SoEnabledElementsList & SoHandleEventAction::getEnabledElements (void) const [protected], [virtual]
Returns a list of the elements used by action instances of this class upon traversal operations.

Reimplemented from SoAction.

  void SoHandleEventAction::setViewportRegion (const SbViewportRegion & newregion)
Set a new viewport region, replacing the one passed in the constructor.

  const SbViewportRegion & SoHandleEventAction::getViewportRegion (void) const
Returns the viewport region this action instance is using.

Advanced Usage:

You can also get the viewport region by accessing it through its element on the traversal state. You do that the following way:

#include <Inventor/elements/SoViewportRegionElement.h>
  SoState * state = action->getState();
  SbViewportRegion vp = SoViewportRegionElement::get(state);

The reason for explaining this is that you can use this generic technique when you need access to state information when you can't seem to find the accessor function you need in the action implementation. You can use it to for instance retrieve the view volume information, for which there are no accessor methods:

#include <Inventor/elements/SoViewVolumeElement.h>
  SoState * state = action->getState();
  SbViewVolume vv = SoViewVolumeElement::get(state);

When you do this on arbitrary action instances, you need to make sure that the given element is enabled for the action before you try to use it. The relevant functions for this are SoState::isElementEnabled() and SoElement::getClassStackIndex().

  void SoHandleEventAction::setEvent (const SoEvent * ev)
Set the event to distribute to the nodes of the scene.

  const SoEvent * SoHandleEventAction::getEvent (void) const
Returns the event this action is handling.

  void SoHandleEventAction::setHandled (void)
Marks the action instance as handled, hence terminates the action.

The action is only marked as handled when a node in the graph 'grabs' the event this action is carrying, so the handled flag will be FALSE after traversal if no nodes wanted the event.

See also:
    isHandled()

  SbBool SoHandleEventAction::isHandled (void) const
Returns whether or not the event has been handled by a node during scene graph traversal.

See also:
    setHandled()

  void SoHandleEventAction::setGrabber (SoNode * node)
Set a node pointer which will get all future events handled by this action until releaseGrabber() is called.

Note that since later SoHandleEventAction invokations are just applied directly on the grabber node, using SoHandleEventAction methods like getCurPath() will return bogus data.

  void SoHandleEventAction::releaseGrabber (void)
Don't send the events to a 'grabber' node anymore, use the default behavior of the action and pass them along to the scene graph again.

See also:
    setGrabber()

  SoNode * SoHandleEventAction::getGrabber (void) const
Returns the grabber node, or NULL if no grabber is active.

  void SoHandleEventAction::setPickRoot (SoNode * node)
Sets the root node that is used for the pick action tracking the cursor.

  SoNode * SoHandleEventAction::getPickRoot (void) const
Returns the root node that is used by nodes that is tracking the cursor.

  void SoHandleEventAction::setPickRadius (const float radiusinpixels)
Sets the pick radius for cursor tracking.

  const SoPickedPoint * SoHandleEventAction::getPickedPoint (void)
Returns the SoPickedPoint information for the intersection point below the cursor.

  const SoPickedPointList & SoHandleEventAction::getPickedPointList (void)
Returns a list of all intersection points below the mouse cursor.

  void SoHandleEventAction::beginTraversal (SoNode * node) [protected], [virtual]
This virtual method is called from SoAction::apply(), and is the entry point for the actual scenegraph traversal.

It can be overridden to initialize the action at traversal start, for specific initializations in the action subclasses inheriting SoAction.

Default method just calls traverse(), which any overridden implementation of the method must do too (or call SoAction::beginTraversal()) to trigger the scenegraph traversal.

Reimplemented from SoAction.

Author

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