Class TMFString

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This item has no description. Showing description inherited from TX3DField.CreateUndefined.

Virtual constructor, that you can use to construct field instance when field class is known only at runtime.

The idea is that in some cases, you need to create fields using variable like FieldClass: TX3DFieldClass. See e.g. TX3DInterfaceDeclaration, VRML 2.0 feature that simply requires this ability, also implementation of TX3DSimpleMultField.Parse and TX3DSimpleMultField.CreateItemBeforeParse.

Later you can initialize such instance from string using it's Parse method.

Note that some exceptional fields simply cannot work when initialized by this constructor: these are SFEnum and SFBitMask fields. They simply need to know their TSFEnum.EnumNames, or TSFBitMask.FlagNames + TSFBitMask.NoneString + TSFBitMask.AllString before they can be parsed. I guess that's one of the reasons why these field types were entirely removed from VRML 2.0.

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This item has no description. Showing description inherited from TX3DField.FastEqualsValue.

Compare value of this field, with other field, fast.

This compares only the values of the fields, not other properties (it doesn't care about names of the fields or such, or default values; only current values). In other words, it compares only the things copied by AssignValue.

This tries to compare very fast, which means that for large (multi-valued) fields it may give up and answer False even when they are in fact equal. So this is usable only for optimization purposes: when it answers True, it is True. When it answers False, it actually doesn't know.

Default implementation in this class (TX3DField) just returns False.

Parse MF field. This class handles parsing fully, usually no need to override this more in descendants. It uses TSingleField.Parse method.

This item has no description. Showing description inherited from TX3DField.X3DType.

Field type in X3D, like 'SFString' or 'MFInt32'. As for VRML/X3D interface declaration statements. In base TX3DField class, this returns XFAny (name indicating any type, used by instantreality and us).

This item has no description. Showing description inherited from TX3DField.CreateEvent.

Create TX3DEvent descendant suitable as exposed event for this field.

This item has no description. Showing description inherited from TX3DField.ParseXMLAttribute.

Parse field value from X3D XML encoded attribute.

Implementation in this class creates a Lexer to parse the string, and calls ParseXMLAttributeLexer.

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Copy another field value, default value and other properties.

This item has no description. Showing description inherited from TX3DField.AssignValue.

Copies the current field value. Contrary to TPersistent.Assign, this doesn't copy the rest of properties.

After setting, our ValueFromIsClause is always changed to False. You can manually change it to True, if this copy indeed was done following "IS" clause.

Descendants implementors notes:

In this class, implementation takes care of setting our ValueFromIsClause to False. In descendants, you should do like

if Source is <appropriate class> then
begin
  inherited;
  Value := Source.value;
end else
  AssignValueRaiseInvalidClass(Source);

This item has no description. Showing description inherited from TX3DField.AssignDefaultValueFromValue.

Set field's default value from the current value.

Note that for now this doesn't guarantee that every possible field's value can be stored as default value. In case of trouble, it will silently record "no default is known" information, so e.g. EqualsDefaultValue will always return False. Our default value mechanisms are sometimes limited, not every value can be a default value. For example, for multiple-valued nodes, we usually cannot save arrays longer than one as default value. This is not a problem, since X3D specification doesn't specify too long default values. But it may be a problem for prototypes, since then user can assign any value as default value. May be corrected in the future.

This item has no description. Showing description inherited from TX3DField.UnassignDefaultValue.

Remove default value, recording that "no default is known". In effect EqualsDefaultValue will always return False.

Checks equality between this and SecondValue field. In addition to inherited(Equals), this checks the actual contents of the items. Note that floating-point values are compared with some tolerance for errors by this method.

This item has no description. Showing description inherited from TX3DField.EqualsDefaultValue.

Whether the value is equal to default. Returns always False in TX3DField, descendants should override it. It is used when writing the field value to X3D file (values that are default do not have to be written, ever).

Set the field's value in a correct way (by sending X3D event, or at least notifying the parent scene).

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