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javax.imageio.metadata
public interface: IIOMetadataFormat [javadoc | source]

All Known Implementing Classes:
    IIOStandardMetadataFormat, IIOMetadataFormatImpl

An object describing the structure of metadata documents returned from IIOMetadata.getAsTree and passed to IIOMetadata.setFromTree and mergeTree. Document structures are described by a set of constraints on the type and number of child elements that may belong to a given parent element type, the names, types, and values of attributes that may belong to an element, and the type and values of Object reference that may be stored at a node.

N.B: classes that implement this interface should contain a method declared as public static getInstance() which returns an instance of the class. Commonly, an implentation will construct only a single instance and cache it for future invocations of getInstance.

The structures that may be described by this class are a subset of those expressible using XML document type definitions (DTDs), with the addition of some basic information on the datatypes of attributes and the ability to store an Object reference within a node. In the future, XML Schemas could be used to represent these structures, and many others.

The differences between IIOMetadataFormat-described structures and DTDs are as follows:

Field Summary
 int CHILD_POLICY_EMPTY    A constant returned by getChildPolicy to indicate that an element may not have any children. In other words, it is required to be a leaf node. 
 int CHILD_POLICY_ALL    A constant returned by getChildPolicy to indicate that an element must have a single instance of each of its legal child elements, in order. In DTD terms, the contents of the element are defined by a sequence a,b,c,d,.... 
 int CHILD_POLICY_SOME    A constant returned by getChildPolicy to indicate that an element must have zero or one instance of each of its legal child elements, in order. In DTD terms, the contents of the element are defined by a sequence a?,b?,c?,d?,.... 
 int CHILD_POLICY_CHOICE    A constant returned by getChildPolicy to indicate that an element must have zero or one children, selected from among its legal child elements. In DTD terms, the contents of the element are defined by a selection a|b|c|d|.... 
 int CHILD_POLICY_SEQUENCE    A constant returned by getChildPolicy to indicate that an element must have a sequence of instances of any of its legal child elements. In DTD terms, the contents of the element are defined by a sequence (a|b|c|d|...)*. 
 int CHILD_POLICY_REPEAT    A constant returned by getChildPolicy to indicate that an element must have zero or more instances of its unique legal child element. In DTD terms, the contents of the element are defined by a starred expression a*. 
 int CHILD_POLICY_MAX    The largest valid CHILD_POLICY_* constant, to be used for range checks. 
 int VALUE_NONE    A constant returned by getObjectValueType to indicate the absence of a user object. 
 int VALUE_ARBITRARY    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set a single, arbitrary value. 
 int VALUE_RANGE    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set a range of values. Both the minimum and maximum values of the range are exclusive. It is recommended that ranges of integers be inclusive on both ends, and that exclusive ranges be used only for floating-point data. 
 int VALUE_RANGE_MIN_INCLUSIVE_MASK    A value that may be or'ed with VALUE_RANGE to obtain VALUE_RANGE_MIN_INCLUSIVE, and with VALUE_RANGE_MAX_INCLUSIVE to obtain VALUE_RANGE_MIN_MAX_INCLUSIVE.

Similarly, the value may be and'ed with the value of getAttributeValueTypeor getObjectValueType to determine if the minimum value of the range is inclusive. 

 int VALUE_RANGE_MAX_INCLUSIVE_MASK    A value that may be or'ed with VALUE_RANGE to obtain VALUE_RANGE_MAX_INCLUSIVE, and with VALUE_RANGE_MIN_INCLUSIVE to obtain VALUE_RANGE_MIN_MAX_INCLUSIVE.

Similarly, the value may be and'ed with the value of getAttributeValueTypeor getObjectValueType to determine if the maximum value of the range is inclusive. 

 int VALUE_RANGE_MIN_INCLUSIVE    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set to a range of values. The minimum (but not the maximum) value of the range is inclusive. 
 int VALUE_RANGE_MAX_INCLUSIVE    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set to a range of values. The maximum (but not the minimum) value of the range is inclusive. 
 int VALUE_RANGE_MIN_MAX_INCLUSIVE    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set a range of values. Both the minimum and maximum values of the range are inclusive. It is recommended that ranges of integers be inclusive on both ends, and that exclusive ranges be used only for floating-point data. 
 int VALUE_ENUMERATION    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set one of a number of enumerated values. In the case of attributes, these values are Strings; for objects, they are Objects implementing a given class or interface.

Attribute values of type DATATYPE_BOOLEAN should be marked as enumerations. 

 int VALUE_LIST    A constant returned by getAttributeValueType and getObjectValueType to indicate that the attribute or user object may be set to a list or array of values. In the case of attributes, the list will consist of whitespace-separated values within a String; for objects, an array will be used. 
 int DATATYPE_STRING    A constant returned by getAttributeDataType indicating that the value of an attribute is a general Unicode string. 
 int DATATYPE_BOOLEAN    A constant returned by getAttributeDataType indicating that the value of an attribute is one of the boolean values 'true' or 'false'. Attribute values of type DATATYPE_BOOLEAN should be marked as enumerations, and the permitted values should be the string literal values "TRUE" or "FALSE", although a plugin may also recognise lower or mixed case equivalents. 
 int DATATYPE_INTEGER    A constant returned by getAttributeDataType indicating that the value of an attribute is a string representation of an integer. 
 int DATATYPE_FLOAT    A constant returned by getAttributeDataType indicating that the value of an attribute is a string representation of a decimal floating-point number. 
 int DATATYPE_DOUBLE    A constant returned by getAttributeDataType indicating that the value of an attribute is a string representation of a double-precision decimal floating-point number. 
Method from javax.imageio.metadata.IIOMetadataFormat Summary:
canNodeAppear,   getAttributeDataType,   getAttributeDefaultValue,   getAttributeDescription,   getAttributeEnumerations,   getAttributeListMaxLength,   getAttributeListMinLength,   getAttributeMaxValue,   getAttributeMinValue,   getAttributeNames,   getAttributeValueType,   getChildNames,   getChildPolicy,   getElementDescription,   getElementMaxChildren,   getElementMinChildren,   getObjectArrayMaxLength,   getObjectArrayMinLength,   getObjectClass,   getObjectDefaultValue,   getObjectEnumerations,   getObjectMaxValue,   getObjectMinValue,   getObjectValueType,   getRootName,   isAttributeRequired
Method from javax.imageio.metadata.IIOMetadataFormat Detail:
 public boolean canNodeAppear(String elementName,
    ImageTypeSpecifier imageType)
    Returns true if the element (and the subtree below
it) is allowed to appear in a metadata document for an image of
the given type, defined by an ImageTypeSpecifier.
For example, a metadata document format might contain an
element that describes the primary colors of the image, which
would not be allowed when writing a grayscale image.
 public int getAttributeDataType(String elementName,
    String attrName)
    Returns one of the constants starting with
DATATYPE_, indicating the format and
interpretation of the value of the given attribute within th
enamed element.  If getAttributeValueType returns
VALUE_LIST, then the legal value is a
whitespace-spearated list of values of the returned datatype.
 public String getAttributeDefaultValue(String elementName,
    String attrName)
    Returns the default value of the named attribute, if it is not
explictly present within the named element, as a
String, or null if no default value
is available.
 public String getAttributeDescription(String elementName,
    String attrName,
    Locale locale)
    Returns a String containing a description of the
named attribute, or null.  The desciption will be
localized for the supplied Locale if possible.


     If locale is null, the current
default Locale returned by Locale.getLocale
will be used.
 public String[] getAttributeEnumerations(String elementName,
    String attrName)
    Returns an array of Strings containing the legal
enumerated values for the given attribute within the named
element.  This method should only be called if
getAttributeValueType returns
VALUE_ENUMERATION.
 public int getAttributeListMaxLength(String elementName,
    String attrName)
    Returns the maximum number of list items that may be used to
define this attribute.  A value of
Integer.MAX_VALUE may be used to specify that
there is no upper bound.  The attribute itself is defined as a
String containing multiple whitespace-separated
items.  This method should only be called if
getAttributeValueType returns
VALUE_LIST.
 public int getAttributeListMinLength(String elementName,
    String attrName)
    Returns the minimum number of list items that may be used to
define this attribute.  The attribute itself is defined as a
String containing multiple whitespace-separated
items.  This method should only be called if
getAttributeValueType returns
VALUE_LIST.
 public String getAttributeMaxValue(String elementName,
    String attrName)
    Returns the maximum legal value for the attribute.  Whether
this value is inclusive or exclusive may be determined by the
value of getAttributeValueType.  The value is
returned as a String; its interpretation is
dependent on the value of getAttributeDataType.
This method should only be called if
getAttributeValueType returns
VALUE_RANGE_*.
 public String getAttributeMinValue(String elementName,
    String attrName)
    Returns the minimum legal value for the attribute.  Whether
this value is inclusive or exclusive may be determined by the
value of getAttributeValueType.  The value is
returned as a String; its interpretation is
dependent on the value of getAttributeDataType.
This method should only be called if
getAttributeValueType returns
VALUE_RANGE_*.
 public String[] getAttributeNames(String elementName)
    Returns an array of Strings listing the names of
the attributes that may be associated with the named element.
 public int getAttributeValueType(String elementName,
    String attrName)
    Returns one of the constants starting with VALUE_,
indicating whether the values of the given attribute within the
named element are arbitrary, constrained to lie within a
specified range, constrained to be one of a set of enumerated
values, or are a whitespace-separated list of arbitrary values.
 public String[] getChildNames(String elementName)
    Returns an array of Strings indicating the names
of the element which are allowed to be children of the named
element, in the order in which they should appear.  If the
element cannot have children, null is returned.
 public int getChildPolicy(String elementName)
    Returns one of the constants starting with
CHILD_POLICY_, indicating the legal pattern of
children for the named element.
 public String getElementDescription(String elementName,
    Locale locale)
    Returns a String containing a description of the
named element, or null.  The desciption will be
localized for the supplied Locale if possible.


     If locale is null, the current
default Locale returned by Locale.getLocale
will be used.
 public int getElementMaxChildren(String elementName)
    Returns the maximum number of children of the named element
with child policy CHILD_POLICY_REPEAT.  For
example, an element representing an entry in an 8-bit color
palette might be allowed to repeat up to 256 times.  A value of
Integer.MAX_VALUE may be used to specify that
there is no upper bound.
 public int getElementMinChildren(String elementName)
    Returns the minimum number of children of the named element
with child policy CHILD_POLICY_REPEAT.  For
example, an element representing color primary information
might be required to have at least 3 children, one for each
primay.
 public int getObjectArrayMaxLength(String elementName)
    Returns the maximum number of array elements that may be used
to define the Object reference within the named
element.  A value of Integer.MAX_VALUE may be used
to specify that there is no upper bound.  This method should
only be called if getObjectValueType returns
VALUE_LIST.
 public int getObjectArrayMinLength(String elementName)
    Returns the minimum number of array elements that may be used
to define the Object reference within the named
element.  This method should only be called if
getObjectValueType returns
VALUE_LIST.
 public Class<?> getObjectClass(String elementName)
    Returns the Class type of the Object
reference stored within the element.  If this element may not
contain an Object reference, an
IllegalArgumentException will be thrown.  If the
class type is an array, this field indicates the underlying
class type (e.g, for an array of ints, this
method would return int.class).


     Object references whose legal values are
defined as a range must implement the Comparable
interface.
 public Object getObjectDefaultValue(String elementName)
    Returns an Objects containing the default
value for the Object reference within
the named element.
 public Object[] getObjectEnumerations(String elementName)
    Returns an array of Objects containing the legal
enumerated values for the Object reference within
the named element.  This method should only be called if
getObjectValueType returns
VALUE_ENUMERATION.


     The Object associated with a node that accepts
emuerated values must be equal to one of the values returned by
this method, as defined by the == operator (as
opposed to the Object.equals method).
 public Comparable<?> getObjectMaxValue(String elementName)
    Returns the maximum legal value for the Object
reference within the named element.  Whether this value is
inclusive or exclusive may be determined by the value of
getObjectValueType.  This method should only be
called if getObjectValueType returns one of the
constants starting with VALUE_RANGE.
 public Comparable<?> getObjectMinValue(String elementName)
    Returns the minimum legal value for the Object
reference within the named element.  Whether this value is
inclusive or exclusive may be determined by the value of
getObjectValueType.  This method should only be
called if getObjectValueType returns one of the
constants starting with VALUE_RANGE.
 public int getObjectValueType(String elementName)
    Returns one of the enumerated values starting with
VALUE_, indicating the type of values
(enumeration, range, or array) that are allowed for the
Object reference.  If no object value can be
stored within the given element, the result of this method will
be VALUE_NONE.


     Object references whose legal values are
defined as a range must implement the Comparable
interface.
 public String getRootName()
    Returns the name of the root element of the format.
 public boolean isAttributeRequired(String elementName,
    String attrName)
    Returns true if the named attribute must be
present within the named element.