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SoMField Class Reference

The SoMField class is the base class for fields which can contain multiple values. More...

#include <Inventor/fields/SoMField.h>

Inheritance diagram for SoMField::

List of all members.

Public Methods
virtual	~SoMField ()
int	getNum (void) const
void	setNum (const int num)
virtual void	deleteValues (int start, int num=-1)
virtual void	insertSpace (int start, int num)
SbBool	set1 (const int index, const char *const valuestring)
void	get1 (const int index, SbString &valuestring)
Static Public Methods
SoType	getClassTypeId (void)
void	initClass (void)
Protected Methods
	SoMField (void)
virtual void	makeRoom (int newnum)
Protected Attributes
int	num
int	maxNum

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Detailed Description

The SoMField class is the base class for fields which can contain multiple values.

All field types which may contain more than one member value inherits this class. SoMField is an abstract class.

Use setValue(), setValues() or set1Value() to set the values of fields inheriting SoMField, and use getValues() or the index operator[] to read values. Example code:

    SoText2 * textnode = new SoText2;
    textnode->ref();

    // Setting multi-field values. /////////////////////////////

    // Set the first value of the SoMFString field of the SoText2 node.
    // The field array will be truncated to only contain this single value.
    textnode->string.setValue("Morten");
    // Full contents of the SoMFString is: [ "Morten" ]

    // The setValue() method and the = operator is interchangeable,
    // so this code line does the same as the previous line.
    textnode->string = "Peder";
    // Full contents of the SoMFString is now: [ "Peder" ]

    // Set the value at index 2. If the field value array contained
    // less than 3 elements before this call, first expand it to contain
    // 3 elements.
    textnode->string.set1Value(2, "Lars");
    // Full contents of the SoMFString is: [ "Peder", <undefined>, "Lars" ]

    // This sets 3 values of the array, starting at index 5. If the
    // array container had less than 8 elements before the setValues()
    // call, the array will first be expanded.
    SbString s[3] = { "Eriksen", "Blekken", "Aas" };
    textnode->string.setValues(5, sizeof(s), s);
    // Full contents of the SoMFString is now:
    //     [ "Peder", <undefined>, "Lars", <undefined>, <undefined>,
    //       "Eriksen", "Blekken", "Aas" ]


    // Inspecting multi-field values. //////////////////////////

    // This will read the second element (counting from zero) if the
    // multivalue field and place it in "val".
    SbString val = textnode->string[2];

    // Gives us a pointer to the array which the multiple-value field
    // is using to store the values. Note that the return value is
    // "const", so you can only read from the array, not write to
    // it.
    const SbString * vals = textnode->string.getValues(0);


    // Modifying multi-field values. ///////////////////////////

    // You can of course modify multifield-values by using the set-
    // and get-methods shown above, but when you're working with
    // big sets of data, this will be ineffective. Then use this
    // technique instead:
    SbString * modvals = textnode->string.startEditing();

    // ... lots of modifications to the "modvals" array here ...

    // Calling the finishEditing() method is necessary for the
    // scene graph to be updated (and re-rendered).
    textnode->string.finishEditing();

The reason it is more effective to wrap many modifications within startEditing() / finishEditing() is because we avoid the stream of notification messages which would otherwise be sent for each and every modification done. Instead there will just be a single notification about the changes, triggered by the finishEditing() call.

When nodes, engines or other types of field containers are written to file, their multiple-value fields are written to file in this format:

    containerclass {
      fieldname [ value0, value1, value2, ...]
      ...
    }

..like this, for instance, a Coordinate3 node providing 6 vertex coordinates in the form of SbVec3f values in its "point" field for e.g. a faceset, lineset or pointset:

     Coordinate3 {
        point [
           -1 1 0, -1 -1 0, 1 -1 0,
           0 2 -1, -2 0 -1, 0 -2 -1,
        ]
     }

See also:

SoSField

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Constructor & Destructor Documentation

SoMField::~SoMField (  )  [virtual]

Destructor in SoMField does nothing. Resource deallocation needs to be done from subclasses.

SoMField::SoMField (  void )  [protected]

Constructor. Initializes number of values in field to zero.

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Member Function Documentation

SoType SoMField::getClassTypeId (  void )  [static]

Returns a unique type identifier for this field class. See also: getTypeId(), SoType Reimplemented from SoField.

int SoMField::getNum (  void )  const [inline]

Returns number of values in this field.

void SoMField::setNum (  const int num )

Set number of values to num. If the current number of values is less than num, the array of values will be truncated from the end, if num is larger than the current number of values, random values will be appended.

void SoMField::deleteValues (  int start, int num = -1 )  [virtual]

Remove value elements from index start up to and including index start + num - 1. Elements with indices larger than the last deleted element will be moved downwards in the value array. If num equals -1, delete from index start and to the end of the array.

void SoMField::insertSpace (  int start, int num )  [virtual]

Insert num "slots" for new value elements from start. The elements already present from start will be moved "upward" in the extended array.

SbBool SoMField::set1 (  const int index, const char *const valuestring )

Set the value at index to the value contained in valuestring. Returns TRUE if a valid value for this field can be extracted from valuestring, otherwise FALSE.

void SoMField::get1 (  const int index, SbString & valuestring )

Return the value at index in the valuestring string.

void SoMField::initClass (  void )  [static]

Internal method called upon initialization of the library (from SoDB::init()) to set up the type system. Reimplemented from SoField. Reimplemented in SoMFBool, SoMFColor, SoMFFloat, SoMFInt32, SoMFMatrix, SoMFName, SoMFPlane, SoMFRotation, SoMFShort, SoMFString, SoMFTime, SoMFUInt32, SoMFUShort, SoMFVec2f, SoMFVec3f, SoMFVec4f, SoMFEnum, SoMFBitMask, SoMFNode, SoMFEngine, and SoMFPath.

void SoMField::makeRoom (  int newnum )  [protected, virtual]

Make room in the field to store newnum values.

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Member Data Documentation

int SoMField::num [protected]

Number of available values.

int SoMField::maxNum [protected]

Number of array "slots" allocated for this field.

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The documentation for this class was generated from the following files:

• SoMField.cpp
• SoMField.h

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