SoEngine.h

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/*=======================================================================
** Author      : Gavin Bell (MMM yyyy)
**=======================================================================*/
/*=======================================================================
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**=======================================================================*/
/*=======================================================================
** Modified by : VSG (MMM YYYY)
**=======================================================================*/
 
 
#ifndef  _SO_ENGINE_
#define  _SO_ENGINE_
 
#include <Inventor/SbBasic.h>
#include <Inventor/fields/SoFieldContainer.h>
#include <Inventor/SoLists.h>
#include <Inventor/SbString.h>
#include <Inventor/SoType.h>
 
//
//  Class: SoEngine
//
//  Base SoEngine class (abstract).
//
 
 
class SoFieldData;
class SoEngineList;
class SoEngineOutput;
class SoEngineOutputList;
class SoEngineOutputData;
class SoField;
class SoOutput;
class SoInput;
 
class  SoEngine : public SoFieldContainer {
 
 public:
 
  static SoType       getClassTypeId();
 
  virtual int         getOutputs(SoEngineOutputList &list) const;
 
  SoEngineOutput *    getOutput(const SbName &outputName) const;
 
  SbBool              getOutputName(const SoEngineOutput *output,
                                    SbName &outputName) const;
 
  SoEngine *          copy() const;
 
  static SoEngine *   getByName(const SbName &name);
  static int          getByName(const SbName &name, SoEngineList &list);
 
 private:
 
  virtual void        evaluate() = 0;
 
 private:
 
  // wrapper for the user's evaluate() engine
  void                evaluateWrapper();
 
  // Propagates modification notification through an instance.
  virtual void        notify(SoNotList *list);
 
  // Initializes base engine class
  static void         initClass();
  static void         exitClass();
 
  // Info on outputs:
  virtual const SoEngineOutputData *getOutputData() const = 0;
 
  // Initialize ALL Inventor engine classes
  static void         initClasses();
  static void         exitClasses();
 
  // Writes instance to SoOutput. (Used only for last stage of writing)
  virtual void        writeInstance(SoOutput *out);
 
  // Copies an instance that is encountered through a field connection
  virtual SoFieldContainer *  copyThroughConnection() const;
 
  // Recursive procedure that determines if this engine should be
  // copied during a copy operation, or just referenced as is
  SbBool              shouldCopy() const;
 
  // A very annoying double notification occurs with engines
  // that enable their outputs during inputChanged; this flag
  // prevents that:
  SbBool              isNotifying() const { return notifying; }
 
 private:
 
  // Constructor, destructor
  SoEngine();
  virtual ~SoEngine();
 
  // Reads stuff into instance. Returns FALSE on error
  virtual SbBool      readInstance(SoInput *in, unsigned short flags);
 
  // This is called whenever the value of an input is changed. The
  // default method does nothing. Subclasses can override this to
  // detect when a specific field is changed.
  virtual void        inputChanged(SoField *whichField);
 
  // This is used by the input&output inheritence mechanism, hidden in
  // the SoSubEngine macros
  static const SoFieldData            **getInputDataPtr()  { return NULL; }
  static const SoEngineOutputData     **getOutputDataPtr() { return NULL; }
 
  // Write output type information for engines that are not built-in.
  void                writeOutputTypes(SoOutput *out);
 
 private:
 
  // update forward connections
  void updateForwardConnections();
 
  static SoType classTypeId;
  SbBool needsEvaluation;        // Dirty bit
  SbBool notifying;
  friend class SoEngineOutput;
};
 
//
//  Class: SoEngineOutput
//
//  Engine outputs.  They are lists of fields to be written into,
//  and a pointer back to the containing engine.
//
 
class  SoEngineOutput {
 
 public:
  SoType              getConnectionType() const;
 
  int                 getForwardConnections(SoFieldList &list) const;
 
  void                enable(SbBool flag);
  SbBool              isEnabled() const       { return enabled; }
 
  SoEngine *          getContainer() const            { return container; }
 
  int getNumConnections() const
  { return connections.getLength(); }
 
private:
 
  SoEngineOutput();
 
  virtual ~SoEngineOutput();
 
private:
  void                setContainer(SoEngine *eng)     { container = eng; }
 
  // Adds/removes connection to field
  void                addConnection(SoField *);
  void                removeConnection(SoField *);
 
  // Returns the fields this output is writing into
  SoField *           operator[](int i) const
    { return connections.get(i); }
 
  // Before evaluating (which is done with the regular field API),
  // we must disable notification on all the fields we're about to
  // write into.  After evaluating, the bits are restored:
  void                prepareToWrite() const;
  void                doneWriting() const;
 
  // update connected object with cached value
  // Note only supported by SoImageVizEngineOutput class
  // Returns FALSE if failed, TRUE if OK
  virtual bool updateConnection()
  { return TRUE; }
 
 private:
  SbBool              enabled;
  SoFieldList         connections;
  SoEngine            *container;
};
 
#endif /* _SO_ENGINE_ */