javax.swing.text
Class StyleContext

java.lang.Object   
  javax.swing.text.StyleContext

All Implemented Interfaces:

Serializable , AbstractDocument.AttributeContext

Direct Known Subclasses:

StyleSheet

public class StyleContext
extends Object   
implements Serializable   , AbstractDocument.AttributeContext   

A pool of styles and their associated resources. This class determines the lifetime of a group of resources by being a container that holds caches for various resources such as font and color that get reused by the various style definitions. This can be shared by multiple documents if desired to maximize the sharing of related resources.

This class also provides efficient support for small sets of attributes and compresses them by sharing across uses and taking advantage of their immutable nature. Since many styles are replicated, the potential for sharing is significant, and copies can be extremely cheap. Larger sets reduce the possibility of sharing, and therefore revert automatically to a less space-efficient implementation.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans^TM has been added to the java.beans package. Please see XMLEncoder .

See Also:

Serialized Form

Nested Class Summary

class	StyleContext.NamedStyle A collection of attributes, typically used to represent character and paragraph styles.
class	StyleContext.SmallAttributeSet This class holds a small number of attributes in an array.

Field Summary

static String

DEFAULT_STYLE The name given to the default logical style attached to paragraphs.

Constructor Summary

StyleContext ()
Creates a new StyleContext object.

Method Summary

AttributeSet	addAttribute (AttributeSet old, Object name, Object value) Adds an attribute to the given set, and returns the new representative set.
AttributeSet	addAttributes (AttributeSet old, AttributeSet attr) Adds a set of attributes to the element.
void	addChangeListener (ChangeListener l) Adds a listener to track when styles are added or removed.
Style	addStyle (String nm, Style parent) Adds a new style into the style hierarchy.
protected MutableAttributeSet	createLargeAttributeSet (AttributeSet a) Create a large set of attributes that should trade off space for time.
protected StyleContext.SmallAttributeSet	createSmallAttributeSet (AttributeSet a) Create a compact set of attributes that might be shared.
Color	getBackground (AttributeSet attr) Takes a set of attributes and turn it into a background color specification.
ChangeListener []	getChangeListeners () Returns an array of all the ChangeListeners added to this StyleContext with addChangeListener().
protected int	getCompressionThreshold () Returns the maximum number of key/value pairs to try and compress into unique/immutable sets.
static StyleContext	getDefaultStyleContext () Returns default AttributeContext shared by all documents that don't bother to define/supply their own context.
AttributeSet	getEmptySet () Fetches an empty AttributeSet.
Font	getFont (AttributeSet attr) Gets the font from an attribute set.
Font	getFont (String family, int style, int size) Gets a new font.
FontMetrics	getFontMetrics (Font f) Returns font metrics for a font.
Color	getForeground (AttributeSet attr) Takes a set of attributes and turn it into a foreground color specification.
static Object	getStaticAttribute (Object key) Returns the object previously registered with registerStaticAttributeKey.
static Object	getStaticAttributeKey (Object key) Returns the String that key will be registered with
Style	getStyle (String nm) Fetches a named style previously added to the document
Enumeration <?>	getStyleNames () Fetches the names of the styles defined.
void	readAttributes (ObjectInputStream in, MutableAttributeSet a) Context-specific handling of reading in attributes
static void	readAttributeSet (ObjectInputStream in, MutableAttributeSet a) Reads a set of attributes from the given object input stream that have been previously written out with writeAttributeSet.
void	reclaim (AttributeSet a) Returns a set no longer needed by the MutableAttributeSet implmentation.
static void	registerStaticAttributeKey (Object key) Registers an object as a static object that is being used as a key in attribute sets.
AttributeSet	removeAttribute (AttributeSet old, Object name) Removes an attribute from the set.
AttributeSet	removeAttributes (AttributeSet old, AttributeSet attrs) Removes a set of attributes for the element.
AttributeSet	removeAttributes (AttributeSet old, Enumeration <?> names) Removes a set of attributes for the element.
void	removeChangeListener (ChangeListener l) Removes a listener that was tracking styles being added or removed.
void	removeStyle (String nm) Removes a named style previously added to the document.
String	toString () Converts a StyleContext to a String.
void	writeAttributes (ObjectOutputStream out, AttributeSet a) Context-specific handling of writing out attributes
static void	writeAttributeSet (ObjectOutputStream out, AttributeSet a) Writes a set of attributes to the given object stream for the purpose of serialization.

Methods inherited from class java.lang.Object

clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait

Field Detail

DEFAULT_STYLE

public static final String    DEFAULT_STYLE

The name given to the default logical style attached to paragraphs.

See Also:

Constant Field Values

Constructor Detail

StyleContext

public StyleContext()

Creates a new StyleContext object.

Method Detail

getDefaultStyleContext

public static final StyleContext    getDefaultStyleContext()

Returns default AttributeContext shared by all documents that don't bother to define/supply their own context.

Returns:

the context

addStyle

public Style    addStyle(String    nm,
                      Style    parent)

Adds a new style into the style hierarchy. Style attributes resolve from bottom up so an attribute specified in a child will override an attribute specified in the parent.

Parameters:

nm - the name of the style (must be unique within the collection of named styles in the document). The name may be null if the style is unnamed, but the caller is responsible for managing the reference returned as an unnamed style can't be fetched by name. An unnamed style may be useful for things like character attribute overrides such as found in a style run.

parent - the parent style. This may be null if unspecified attributes need not be resolved in some other style.

Returns:

the created style

removeStyle

public void removeStyle(String    nm)

Removes a named style previously added to the document.

Parameters:

nm - the name of the style to remove

getStyle

public Style    getStyle(String    nm)

Fetches a named style previously added to the document

Parameters:

nm - the name of the style

Returns:

the style

getStyleNames

public Enumeration   <?> getStyleNames()

Fetches the names of the styles defined.

Returns:

the list of names as an enumeration

addChangeListener

public void addChangeListener(ChangeListener    l)

Adds a listener to track when styles are added or removed.

Parameters:

l - the change listener

removeChangeListener

public void removeChangeListener(ChangeListener    l)

Removes a listener that was tracking styles being added or removed.

Parameters:

l - the change listener

getChangeListeners

public ChangeListener   [] getChangeListeners()

Returns an array of all the ChangeListeners added to this StyleContext with addChangeListener().

Returns:

all of the ChangeListeners added or an empty array if no listeners have been added

Since:

1.4

getFont

public Font    getFont(AttributeSet    attr)

Gets the font from an attribute set. This is implemented to try and fetch a cached font for the given AttributeSet, and if that fails the font features are resolved and the font is fetched from the low-level font cache.

Parameters:

attr - the attribute set

Returns:

the font

getForeground

public Color    getForeground(AttributeSet    attr)

Takes a set of attributes and turn it into a foreground color specification. This might be used to specify things like brighter, more hue, etc. By default it simply returns the value specified by the StyleConstants.Foreground attribute.

Parameters:

attr - the set of attributes

Returns:

the color

getBackground

public Color    getBackground(AttributeSet    attr)

Takes a set of attributes and turn it into a background color specification. This might be used to specify things like brighter, more hue, etc. By default it simply returns the value specified by the StyleConstants.Background attribute.

Parameters:

attr - the set of attributes

Returns:

the color

getFont

public Font    getFont(String    family,
                    int style,
                    int size)

Gets a new font. This returns a Font from a cache if a cached font exists. If not, a Font is added to the cache. This is basically a low-level cache for 1.1 font features.

Parameters:

family - the font family (such as "Monospaced")

style - the style of the font (such as Font.PLAIN)

size - the point size >= 1

Returns:

the new font

getFontMetrics

public FontMetrics    getFontMetrics(Font    f)

Returns font metrics for a font.

Parameters:

f - the font

Returns:

the metrics

addAttribute

public AttributeSet    addAttribute(AttributeSet    old,
                                 Object