Class TSFNode

Unit

VRMLNodes

Declaration

type TSFNode = class(TVRMLSingleField)

Description

SFNode VRML field. It's defined in this unit, not in VRMLFields, since it uses TVRMLNode definition. NULL value of the field is indicated by Value field = nil. This field has always the same default value: NULL.

Note that we store AllowedChildren list, which is a list of classes allowed as a Value (also nil is always allowed). But this is used only to produce warnings for a user. You should never assert that Value actually is one the requested classes. We want to keep here even not allowed items, because we want operation "read from VRML file + write to VRML file" to be as non-destructible as possible. So if user wrote invalid class hierarchy, we will output this invalid class hierarchy.

Hierarchy

• TPersistent
• TVRMLField
• TVRMLSingleField
• TSFNode

Overview

Methods

	procedure SaveToStreamValue(SaveProperties: TVRMLSaveToStreamProperties); override;
	constructor CreateUndefined(const AName: string); override;
	constructor Create(AParentNode: TVRMLNode; const AName: string; const AnAllowedChildren: array of TVRMLNodeClass); overload;
	constructor Create(AParentNode: TVRMLNode; const AName: string; AnAllowedChildren: TVRMLNodeClassesList); overload;
	destructor Destroy; override;
	procedure Parse(Lexer: TVRMLLexer; IsClauseAllowed: boolean); override;
	function EqualsDefaultValue: boolean; override;
	function Equals(SecondValue: TVRMLField; const EqualityEpsilon: Single): boolean; override;
	procedure Assign(Source: TPersistent); override;
	procedure AssignValue(Source: TVRMLField); override;
	class function VRMLTypeName: string; override;

Properties

	property AllowedChildrenAll: boolean read FAllowedChildrenAll write FAllowedChildrenAll;
	property Value: TVRMLNode read FValue write SetValue;
	property ParentNode: TVRMLNode read FParentNode;

Description

Methods

	procedure SaveToStreamValue(SaveProperties: TVRMLSaveToStreamProperties); override;

	constructor CreateUndefined(const AName: string); override;

	constructor Create(AParentNode: TVRMLNode; const AName: string; const AnAllowedChildren: array of TVRMLNodeClass); overload;

	constructor Create(AParentNode: TVRMLNode; const AName: string; AnAllowedChildren: TVRMLNodeClassesList); overload;
Constructor that takes AnAllowedChildren as TVRMNodeClassesList. Note that we copy the contents of AnAllowedChildren, not the reference.

	destructor Destroy; override;

	procedure Parse(Lexer: TVRMLLexer; IsClauseAllowed: boolean); override;

	function EqualsDefaultValue: boolean; override;

	function Equals(SecondValue: TVRMLField; const EqualityEpsilon: Single): boolean; override;

	procedure Assign(Source: TPersistent); override;

	procedure AssignValue(Source: TVRMLField); override;

	class function VRMLTypeName: string; override;

Properties

property AllowedChildrenAll: boolean read FAllowedChildrenAll write FAllowedChildrenAll;

This says that all children are allowed, regardless of AllowedChildren value. CreateUndefined creates always object with AllowedChildrenAll = True (otherwise AllowedChildren list is empty and nothing would be allowed; but for e.g. fields in instantiated prototypes, we must initially just allow all, otherwise valid prototypes with SFNode/MFNode would cause warnings when parsing). Other constructors set AllowedChildren to something meaningful and set this to False. You can change this to True then if you consciously want to turn this check off.

	property Value: TVRMLNode read FValue write SetValue;

	property ParentNode: TVRMLNode read FParentNode;