Class TSFImage

Unit

VRMLFields

Declaration

type TSFImage = class(TVRMLSingleField)

Description

Base class for all VRML fields.

Common notes for all descendants: most of them expose field or property "Value", this is (surprise, surprise!) the value of the field. Many of them also expose DefaultValue and DefaultValueExists fields/properties, these should be the default VRML value for this field. You can even change DefaultValue after the object is created.

Most of descendants include constructor that initializes both DefaultValue and Value to the same thing, as this is what you usually want.

Some notes about Assign method (inherited from TPersistent and overridied appropriately in TVRMLField descendants):

1. There are some exceptions, but usually assignment is possible only when source and destination field classes are equal.

2. Assignment tries to copy everything: name, default value, IsClause*, Exposed, and of course current value.

   If you want to copy only the current value, use AssignValue (or AssignLerp, where available).

Hierarchy

• TPersistent
• TVRMLField
• TVRMLSingleField
• TSFImage

Overview

Fields

Value: TImage;

Methods

	procedure SaveToStreamValue(SaveProperties: TVRMLSaveToStreamProperties); override;
	constructor Create(const AName: string; const AValue: TImage);
	constructor CreateUndefined(const AName: string); override;
	destructor Destroy; override;
	procedure Parse(Lexer: TVRMLLexer; IsClauseAllowed: 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;

Description

Fields

	Value: TImage;
Value is owned by this object - i.e. in destructor we do Value.Free. Value may be IsNull, and then we know that there is no image recorded in this field. Value may never be nil. Remember — Value is freed by this object, but if you're altering it in any other way, you're responsible for good memory managing.

Methods

	procedure SaveToStreamValue(SaveProperties: TVRMLSaveToStreamProperties); override;

	constructor Create(const AName: string; const AValue: TImage);
Parameters AValue is the initial value for Value. Note - our constructor COPIES passed reference AValue, not it's contents (I mean, we do Value := AValue, NOT Value := ImageCopy(AValue), so don't Free image given to us (at least, don't do this without clearing our Value field)). You can pass AValue = nil, then Value will be inited to null image TRGBImage.Create.

	constructor CreateUndefined(const AName: string); override;

	destructor Destroy; override;

	procedure Parse(Lexer: TVRMLLexer; IsClauseAllowed: 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;