SoWriteAction(3) The SoWriteAction class writes a scene graph to file.

SYNOPSIS


#include <Inventor/actions/SoWriteAction.h>

Inherits SoAction.

Public Member Functions


virtual SoType getTypeId (void) const

SoWriteAction (void)

SoWriteAction (SoOutput *out)

virtual ~SoWriteAction (void)

SoOutput * getOutput (void) const

void continueToApply (SoNode *node)

void continueToApply (SoPath *path)

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)

virtual SbBool shouldCompactPathLists (void) const

Static Protected Member Functions


static SoEnabledElementsList * getClassEnabledElements (void)

static SoActionMethodList * getClassActionMethods (void)

Additional Inherited Members

Detailed Description

The SoWriteAction class writes a scene graph to file.

When applied to a scene, this action writes its contents to the stream contained within an SoOutput instance. This can be a file, a memory buffer or a system filehandle like stdout, for instance.

All information considered part of the scene graph should be written out, including not only nodes, but also the nodes' field values, global fields (at least those with connections inside the scene the action is applied to), engines in the scene, paths, etc.

The scene is written in the Open Inventor file format. Files in this format can be parsed into their scene graph structures by using the SoDB::readAll() method (SoDB also contains a few other import methods you can use).

Here's a complete, stand-alone usage example which shows how to write a scene graph to a memory buffer: 

  #include <Inventor/SoDB.h>
  #include <Inventor/actions/SoWriteAction.h>
  #include <Inventor/nodes/SoCone.h>
  #include <Inventor/nodes/SoSeparator.h>
  static char * buffer;
  static size_t buffer_size = 0;
  static void *
  buffer_realloc(void * bufptr, size_t size)
  {
    buffer = (char *)realloc(bufptr, size);
    buffer_size = size;
    return buffer;
  }
  static SbString
  buffer_writeaction(SoNode * root)
  {
    SoOutput out;
    buffer = (char *)malloc(1024);
    buffer_size = 1024;
    out.setBuffer(buffer, buffer_size, buffer_realloc);
    SoWriteAction wa(&out);
    wa.apply(root);
    SbString s(buffer);
    free(buffer);
    return s;
  }
  int
  main(int argc, char ** argv)
  {
    SoDB::init();
    SoSeparator * root = new SoSeparator;
    root->ref();
    root->addChild(new SoCone);
    SbString s = buffer_writeaction(root);
    (void)fprintf(stdout, '%s, s.getString());
    root->unref();
    return 0;
  }

See also:

SoOutput

Constructor & Destructor Documentation

SoWriteAction::SoWriteAction (void)

Default constructor. Output will be written to stdout in ASCII format.

SoWriteAction::SoWriteAction (SoOutput *out)

Constructor. Output will be written via the out object.

SoWriteAction::~SoWriteAction (void) [virtual]

Destructor.

Member Function Documentation

SoType SoWriteAction::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.

SoType SoWriteAction::getClassTypeId (void) [static]

Returns the run-time type object associated with instances of this class.

Reimplemented from SoAction.

void SoWriteAction::addMethod (const SoTypetype, SoActionMethodmethod) [static]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

void SoWriteAction::enableElement (const SoTypetype, const intstackindex) [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 & SoWriteAction::getEnabledElements (void) const [protected], [virtual]

Returns a list of the elements used by action instances of this class upon traversal operations.

Reimplemented from SoAction.

SoEnabledElementsList * SoWriteAction::getClassEnabledElements (void) [static], [protected]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

This method not available in the original OIV API, see SoSubAction.h for explanation.

Reimplemented from SoAction.

SoActionMethodList * SoWriteAction::getClassActionMethods (void) [static], [protected]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

This method not available in the original OIV API, see SoSubAction.h for explanation.

Reimplemented from SoAction.

void SoWriteAction::initClass (void) [static]

Initializes the run-time type system for this class, and sets up the enabled elements and action method list.

Reimplemented from SoAction.

SoOutput * SoWriteAction::getOutput (void) const

Returns a pointer to the SoOutput object we're using when writing the scene graph.

void SoWriteAction::continueToApply (SoNode *node)

Applies the write method to the subgraph starting at node with the current SoOutput instance, without resetting any of the internal state of the action instance.

This should normally be for internal use only.

void SoWriteAction::continueToApply (SoPath *path)

Applies the write method to path with the current SoOutput instance, without resetting any of the internal state of the action instance.

This should normally be for internal use only.

void SoWriteAction::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.

SbBool SoWriteAction::shouldCompactPathLists (void) const [protected], [virtual]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Compact path lists are not implemented in Coin (yet), but if they are, SoWriteAction should return FALSE here -- it would only be extra overhead for the SoWriteAction to have pathlists compacted before traversal.

Seems like a silly optimization to me, though.. :^/ 20000306 mortene.

Author

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