trusty (3) SoEventCallback.3.gz

NAME

       SoEventCallback -

       The SoEventCallback class provides functionality for catching events.

       Use SoEventCallback nodes in the scenegraph for catching user interaction events with the scenegraph's
       render canvas.

SYNOPSIS

       #include <Inventor/nodes/SoEventCallback.h>

       Inherits SoNode.

   Public Member Functions
       virtual SoType getTypeId (void) const
           Returns the type identification of an object derived from a class inheriting SoBase. This is used for
           run-time type checking and 'downward' casting.
       SoEventCallback (void)
       void setPath (SoPath *path)
       const SoPath * getPath (void)
       void addEventCallback (SoType eventtype, SoEventCallbackCB *f, void *userdata=NULL)
       void removeEventCallback (SoType eventtype, SoEventCallbackCB *f, void *userdata=NULL)
       SoHandleEventAction * getAction (void) const
       const SoEvent * getEvent (void) const
       const SoPickedPoint * getPickedPoint (void) const
       void setHandled (void)
       SbBool isHandled (void) const
       void grabEvents (void)
       void releaseEvents (void)

   Static Public Member Functions
       static SoType getClassTypeId (void)
       static void initClass (void)

   Protected Member Functions
       virtual const SoFieldData * getFieldData (void) const
       virtual ~SoEventCallback ()
       virtual void handleEvent (SoHandleEventAction *action)

   Static Protected Member Functions
       static const SoFieldData ** getFieldDataPtr (void)

   Additional Inherited Members

Detailed Description

       The SoEventCallback class provides functionality for catching events.

       Use SoEventCallback nodes in the scenegraph for catching user interaction events with the scenegraph's
       render canvas.

       This is how event handling works in Coin: when the user interacts with the render canvas, for instance by
       using the mouse pointer or by hitting the keyboard, the GUI interface toolkit (ie SoQt, SoWin, SoXt, Sc21
       ...) will catch the event and translate it from a windowsystem-specific event to a generic Coin event.
       (For the types of generic Coin events, see the classes derived from SoEvent.) This event will then be
       wrapped inside a SoHandleEventAction and applied to the scenegraph. All this happens within the
       So[Qt|Xt|Win|...] toolkit.

       The SoHandleEventAction then traverses the scenegraph, delivering the event to any node type which 'is
       interested' in it. The SoEventCallback nodetype catches the action and forwards the event to a callback
       function set up by the application programmer.

       Be careful about which position in the scenegraph you insert SoEventCallback nodes if you are also using
       any of the built-in Coin library elements which are interested in user interaction events (like for
       instance the dragger and manipulator classes and the SoSelection nodes). These Coin elements might catch
       the event for themselves, short-circuiting the SoHandleEventAction traversal so the event will never
       reach the SoEventCallback node(s) you insert.

       FILE FORMAT/DEFAULTS:

       EventCallback {
       }

Constructor & Destructor Documentation

   SoEventCallback::SoEventCallback (void)
       Constructor.

   SoEventCallback::~SoEventCallback () [protected],  [virtual]
       Destructor.

Member Function Documentation

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

       void foo(SoNode * node)
       {
         if (node->getTypeId() == SoFile::getClassTypeId()) {
           SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
         }
       }

       For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or
       others: 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 for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and
       SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

       For more information on writing Coin extensions, see the class documentation of the toplevel superclasses
       for the various class groups.

       Implements SoBase.

   const SoFieldData * SoEventCallback::getFieldData (void) const [protected],  [virtual]
       Returns a pointer to the class-wide field data storage object for this instance. If no fields are
       present, returns NULL.

       Reimplemented from SoFieldContainer.

   void SoEventCallback::setPath (SoPath *pathptr)
       Sets the path that must be picked before the registered callbacks are invoked. If NULL, callbacks will be
       invoked for every event that matches the callback event type.

       See Also:
           getPath()

   const SoPath * SoEventCallback::getPath (void)
       Returns the path that must be picked before callbacks are invoked.

       See Also:
           setPath()

   void SoEventCallback::addEventCallback (SoTypeeventtype, SoEventCallbackCB *f, void *userdata = NULL)
       Set up a callback function f which will be invoked for the given eventtype. userdata will be given as the
       first argument to the function.

   void SoEventCallback::removeEventCallback (SoTypeeventtype, SoEventCallbackCB *f, void *userdata = NULL)
       Unregister the given callback function f.

   SoHandleEventAction * SoEventCallback::getAction (void) const
       Returns the SoHandleEventAction instance currently traversing the scene graph with the SoEvent-derived
       event object.

   const SoEvent * SoEventCallback::getEvent (void) const
       Returns a pointer to the event object which is currently being sent through the scenegraph.

       If your application code handles the event, you probably want to call SoEventCallback::setHandled() to
       notify the SoHandleEventAction that it should stop traversing the scenegraph with the event.

   const SoPickedPoint * SoEventCallback::getPickedPoint (void) const
       Returns the picked point for the current handle event traversal.

       This is obviously only related to events which can be considered 'pick-style' events, like mousebutton
       presses.

   void SoEventCallback::setHandled (void)
       Use this method from a callback function to notify the node that the event has been handled.

       The rest of the callbacks registered with the node will still be called, but further SoEventCallback
       nodes in the scene will not be notified about the event, neither will any other Coin elements in the
       scenegraph (like for instance SoDragger objects, SoSelection nodes or manipulators).

       Since callbacks registered within the same SoEventCallback node will still be invoked after the event has
       been handled, it is likely that you should use SoEventCallback::isHandled() to check for this condition
       from your callback functions.

   SbBool SoEventCallback::isHandled (void) const
       Check whether or not the event from the SoHandleEventAction has been handled.

   void SoEventCallback::grabEvents (void)
       Set up the node so all future events (until releaseEvents() is called) in Coin will be directly forwarded
       to this node.

   void SoEventCallback::releaseEvents (void)
       Do not grab event handling any more.

       See Also:
           grabEvents()

   void SoEventCallback::handleEvent (SoHandleEventAction *action) [protected],  [virtual]
       Invokes the registered callback functions.

       Reimplemented from SoNode.

Author

       Generated automatically by Doxygen for Coin from the source code.