SoSelection(3)

NAME
SoSelection - The SoSelection class manages a list of selected nodes.

Inserting an SoSelection node in your scene graph enables you to let the user 'pick' with the left mousebutton to select/deselect objects below the SoSelection node.

SYNOPSIS

#include <Inventor/nodes/SoSelection.h>

Inherits SoSeparator.

Inherited by SoExtSelection.

  Public Types
enum Policy { SINGLE, TOGGLE, SHIFT }

  Public Member Functions
virtual SoType getTypeId (void) const
SoSelection (void)
SoSelection (const int nChildren)
void select (const SoPath *path)
void select (SoNode *node)
void deselect (const SoPath *path)
void deselect (const int which)
void deselect (SoNode *node)
void toggle (const SoPath *path)
void toggle (SoNode *node)
SbBool isSelected (const SoPath *path) const
SbBool isSelected (SoNode *node) const
void deselectAll (void)
int getNumSelected (void) const
const SoPathList * getList (void) const
SoPath * getPath (const int index) const
SoPath * operator[] (const int i) const
void addSelectionCallback (SoSelectionPathCB *f, void *userData=NULL)
void removeSelectionCallback (SoSelectionPathCB *f, void *userData=NULL)
void addDeselectionCallback (SoSelectionPathCB *f, void *userData=NULL)
void removeDeselectionCallback (SoSelectionPathCB *f, void *userData=NULL)
void addStartCallback (SoSelectionClassCB *f, void *userData=NULL)
void removeStartCallback (SoSelectionClassCB *f, void *userData=NULL)
void addFinishCallback (SoSelectionClassCB *f, void *userData=NULL)
void removeFinishCallback (SoSelectionClassCB *f, void *userData=NULL)
void setPickFilterCallback (SoSelectionPickCB *f, void *userData=NULL, const SbBool callOnlyIfSelectable=TRUE)
void setPickMatching (const SbBool pickMatching)
SbBool isPickMatching (void) const
SbBool getPickMatching (void) const
void addChangeCallback (SoSelectionClassCB *f, void *userData=NULL)
void removeChangeCallback (SoSelectionClassCB *f, void *userData=NULL)

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

  Public Attributes
SoSFEnum policy

  Protected Member Functions
virtual const SoFieldData * getFieldData (void) const
virtual ~SoSelection ()
void invokeSelectionPolicy (SoPath *path, SbBool shiftDown)
void performSingleSelection (SoPath *path)
void performToggleSelection (SoPath *path)
SoPath * copyFromThis (const SoPath *path) const
void addPath (SoPath *path)
void removePath (const int which)
int findPath (const SoPath *path) const
virtual void handleEvent (SoHandleEventAction *action)

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

  Protected Attributes
SoPathList selectionList
SoCallbackList * selCBList
SoCallbackList * deselCBList
SoCallbackList * startCBList
SoCallbackList * finishCBList
SoSelectionPickCB * pickCBFunc
void * pickCBData
SbBool callPickCBOnlyIfSelectable
SoCallbackList * changeCBList
SoPath * mouseDownPickPath
SbBool pickMatching

  Additional Inherited Members

Detailed Description

The SoSelection class manages a list of selected nodes.

Inserting an SoSelection node in your scene graph enables you to let the user 'pick' with the left mousebutton to select/deselect objects below the SoSelection node. Using an SoBoxHighlightRenderAction or an SoLineHighlightRenderAction to render scenegraphs containing SoSelection nodes provides a convenient way of providing visual feedback about the selections to the application user.

Beware that one common faulty assumption which is made about the node is that the scene will automatically be re-rendered whenever the user pick objects. This is not the case, the application programmer must himself schedule a redraw. A straightforward way to accomplish this is to SoNode::touch() the SoSelection node in the selection / deselection callback.

A 'skeleton' for basic use of SoSelection nodes is given below:

extern SoSeparator * make_scenegraph( void );
static SoSelection * selection = NULL;
// Callback function triggered for selection / deselection.
void made_selection( void * userdata, SoPath * path )
{
  (void)fprintf( stdout, "%sselected %s,
                 userdata == (void *)1L ? "" : "de",
                 path->getTail()->getTypeId().getName().getString() );
  selection->touch(); // to redraw
}
// *************************************************************************
// Print a quick instructions notice on stdout.
void show_instructions( void )
{
  (void)fprintf( stdout, "his example program demonstrates the use of the SoSelection node type. );
  (void)fprintf( stdout, "uick instructions:n" );
  (void)fprintf( stdout, "  * pick with left mouse button );
  (void)fprintf( stdout, "  * hold SHIFT to select multiple objects );
  (void)fprintf( stdout, "  * hit ESC to toggle back and forth to view mode );
  (void)fprintf( stdout, " );
}
// *************************************************************************
int main( int argc, char ** argv )
{
  QWidget * window = SoQt::init( argv[0] );
  show_instructions();
  selection = new SoSelection;
  selection->policy = SoSelection::SHIFT;
  selection->ref();
  selection->addChild( make_scenegraph() );
  selection->addSelectionCallback( made_selection, (void *)1L );
  selection->addDeselectionCallback( made_selection, (void *)0L );
  SoQtExaminerViewer * examinerviewer = new SoQtExaminerViewer( window );
  examinerviewer->setSceneGraph( selection );
  examinerviewer->setGLRenderAction( new SoBoxHighlightRenderAction );
  examinerviewer->setViewing( FALSE );
  examinerviewer->show();
  SoQt::show( window );
  SoQt::mainLoop();
  delete examinerviewer;
  selection->unref();
  return 0;
}

This node is not initialized in SoDB::init(), since it is part of the interaction kit 'add-on'. Before using this node, you should therefore call SoInteraction::init(). If you're using one of the standard GUI-toolkits (SoXt / SoQt / SoWin) SoInteraction::init() will be called for you from the So[Xt|Qt|Win]::init() method and you don't have to worry about it.

With regard to using multiple SoSelection nodes at the same time in the same scene graph: this is possible, but it is not straightforward. The standard viewers provided by SoQt, SoWin, et al, will only snoop on one SoSelection node (part of the the legacy API from SGI's InventorXt), so selection changes on the others doesn't trigger redraws. You don't necessarily see what's happening in other words. You'll have to hook up manually and trigger redraws yourself.

Also be aware that when having multiple SoSelection nodes in the scene graph active at the same time, the SoHandleEventAction traversals that you intend for selection-change on one SoSelection node will also affect all the other SoSelection nodes in the scene -- usually delesecting everything below them since you will be clicking outside the selectable objects. You'll therefore also have to manually override that behaviour, if you want selection change on one SoSelection node to not affect the others.

FILE FORMAT/DEFAULTS:

Selection {
    renderCaching AUTO
    boundingBoxCaching AUTO
    renderCulling AUTO
    pickCulling AUTO
    policy SHIFT
}

Member Enumeration Documentation

  enum SoSelection::Policy
Enum for different pick policies.

Enumerator

SINGLE
    Only one object can be selected at any time. When the user picks a new object, the previous selection will be unselected. If the user picks on nothing, the current selection will be unselected.

Note that if a new selection matches one already present in the selection list, neither a deselect nor a select notification callback will be made about that selection path.

TOGGLE
    Picking an object toggles its selection state.

SHIFT
    Same as SINGLE, but when shift key is pressed the selection policy will be changed to TOGGLE.

Constructor & Destructor Documentation

  SoSelection::SoSelection (void)
Default constructor.

  SoSelection::SoSelection (const int nChildren)
Constructor.

The argument should be the approximate number of children which is expected to be inserted below this node. The number need not be exact, as it is only used as a hint for better memory resource allocation.

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

Member Function Documentation

  SoType SoSelection::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.

Reimplemented from SoSeparator.

Reimplemented in SoExtSelection.

  const SoFieldData * SoSelection::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 SoSeparator.

Reimplemented in SoExtSelection.

  void SoSelection::select (const SoPath * path)
Adds path to the list of selected objects.

  void SoSelection::select (SoNode * node)
Adds node to the list of selected objects. The scene graph below the Selection node will be searched, and the path to node will be added if found.

  void SoSelection::deselect (const SoPath * path)
Remove path from the list of selected objects.

  void SoSelection::deselect (const int which)
Remove objects which from the list of selected objects.

  void SoSelection::deselect (SoNode * node)
Remove node from the list of selected objects. The scene graph below the Selection node will be searched, and the path to node will be removed if found.

  void SoSelection::toggle (const SoPath * path)
If path is not already selected, add path to the list of selected objects. Otherwise remove path from the list of selected objects.

  void SoSelection::toggle (SoNode * node)
If node is not already selected, add path to the list of selected objects. Otherwise remove node from the list of selected objects.

  SbBool SoSelection::isSelected (const SoPath * path) const
Return TRUE if path is in the list of selected objects.

  SbBool SoSelection::isSelected (SoNode * node) const
Return TRUE if the path to node is in the list of selected objects.

  void SoSelection::deselectAll (void)
Clears the selection list.

  int SoSelection::getNumSelected (void) const
Returns the number of selected objects.

  const SoPathList * SoSelection::getList (void) const
Returns the list of selected objects.

  SoPath * SoSelection::getPath (const int index) const
Returns the index'th selected objects.

  SoPath * SoSelection::operator[] (const int i) const
Operator for accessing selected objects.

  void SoSelection::addSelectionCallback (SoSelectionPathCB * f, void * userData = NULL)
Adds a callback which will be called every time an object is selected.

See also:
    removeSelectionCallback()

  void SoSelection::removeSelectionCallback (SoSelectionPathCB * f, void * userData = NULL)
Removes one of the selection callbacks.

See also:
    addSelectionCallback()

  void SoSelection::addDeselectionCallback (SoSelectionPathCB * f, void * userData = NULL)
Adds a callback which will be called every time an object is deselected.

See also:
    removeDeselectionCallback()

  void SoSelection::removeDeselectionCallback (SoSelectionPathCB * f, void * userData = NULL)
Removes one of the deselection callbacks.

See also:
    addDeselctionCallback()

  void SoSelection::addStartCallback (SoSelectionClassCB * f, void * userData = NULL)
Adds a callback which will be invoked when the user start an interactive change to the list of selected objects.

This callback is useful for storing the old selection list for undo/redo functionality.

See also:
    addFinishCallback()

  void SoSelection::removeStartCallback (SoSelectionClassCB * f, void * userData = NULL)
Removes f from the list of start callbacks.

See also:
    addStartCallback()

  void SoSelection::addFinishCallback (SoSelectionClassCB * f, void * userData = NULL)
Adds a callback which will be invoked when the user has finished an interactive change to the list of selected objects.

See also:
    addStartCallback()

  void SoSelection::removeFinishCallback (SoSelectionClassCB * f, void * userData = NULL)
Removes f from the list og finish callbacks.

See also:
    addFinishCallback()

  void SoSelection::setPickFilterCallback (SoSelectionPickCB * f, void * userData = NULL, const SbBool callOnlyIfSelectable = TRUE)
Sets the pick filter callback. This callback will be called when a path is about to be added to or removed from the list of selected objects. The callback function should return a replacement path that should be used instead of the picked path. The returned path will be ref'ed, copied, and then unref'ed again by the SoSelection node.

If no callback is set (the default), the picked path will be used for selecting/deselecting.

Possible return values from the callback:

•   NULL: simulate that nothing was picked. This will clear the selection for the SINGLE policy. The handle event action will be halted.
•   A path: the path will be selected/deselected. The handle event action will be halted.
•   A path containing only the Selection node: as NULL, but action will not be halted.
•   An empty path or a path not containing the Selection node: the pick will be ignored.
if callOnlyIfSelectable is TRUE, the callback will only be called if the Selection node is in the picked path.

  void SoSelection::setPickMatching (const SbBool pickmatchflag)
When pickmatchflag is TRUE (the default), the mouse button release pick must match the mouse button press pick before object is selected/deselected.
This flag should normally not be of interest to application programmers.

  SbBool SoSelection::isPickMatching (void) const
Returns TRUE if pick matching is enabled.
See also:
    setPickMatching()

  SbBool SoSelection::getPickMatching (void) const
Returns TRUE if pick matching is enabled.
See also:
    setPickMatching()

  void SoSelection::addChangeCallback (SoSelectionClassCB * f, void * userData = NULL)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.Used by render area to receive notification when the selection list changes.

  void SoSelection::removeChangeCallback (SoSelectionClassCB * f, void * userData = NULL)
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer. Used by render area to receive notification when the selection list changes.

  void SoSelection::invokeSelectionPolicy (SoPath * path, SbBool shiftdown) [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoSelection::performSingleSelection (SoPath * path) [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoSelection::performToggleSelection (SoPath * path) [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoPath * SoSelection::copyFromThis (const SoPath * path) const [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoSelection::addPath (SoPath * path) [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoSelection::removePath (const int which) [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  int SoSelection::findPath (const SoPath * path) const [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void SoSelection::handleEvent (SoHandleEventAction * action) [protected], [virtual]
Action method for SoHandleEventAction.
Inspects the event data from action, and processes it if it is something which this node should react to.
Nodes influencing relevant state variables for how event handling is done also overrides this method.
Reimplemented from SoSeparator.
Reimplemented in SoExtSelection.

Member Data Documentation

  SoSFEnum SoSelection::policy
Field for selection policy. Default value is SHIFT.

  SoPathList SoSelection::selectionList [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoCallbackList * SoSelection::selCBList [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoCallbackList * SoSelection::deselCBList [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoCallbackList * SoSelection::startCBList [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoCallbackList * SoSelection::finishCBList [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoSelectionPickCB * SoSelection::pickCBFunc [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  void * SoSelection::pickCBData [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoSelection::callPickCBOnlyIfSelectable [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoCallbackList * SoSelection::changeCBList [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SoPath * SoSelection::mouseDownPickPath [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

  SbBool SoSelection::pickMatching [protected]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Author
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