StyleSheet JDK 1.6)

Description

public class StyleSheet

Support for defining the visual characteristics of HTML views being rendered.

Support for defining the visual characteristics of HTML views being rendered. The StyleSheet is used to translate the HTML model into visual characteristics. This enables views to be customized by a look-and-feel, multiple views over the same model can be rendered differently, etc. This can be thought of as a CSS rule repository. The key for CSS attributes is an object of type CSS.Attribute. The type of the value is up to the StyleSheet implementation, but the toString method is required to return a string representation of CSS value.

The primary entry point for HTML View implementations to get their attributes is the getViewAttributes method. This should be implemented to establish the desired policy used to associate attributes with the view. Each HTMLEditorKit (i.e. and therefore each associated JEditorPane) can have its own StyleSheet, but by default one sheet will be shared by all of the HTMLEditorKit instances. HTMLDocument instance can also have a StyleSheet, which holds the document-specific CSS specifications.

In order for Views to store less state and therefore be more lightweight, the StyleSheet can act as a factory for painters that handle some of the rendering tasks. This allows implementations to determine what they want to cache and have the sharing potentially at the level that a selector is common to multiple views. Since the StyleSheet may be used by views over multiple documents and typically the HTML attributes don't effect the selector being used, the potential for sharing is significant.

The rules are stored as named styles, and other information is stored to translate the context of an element to a rule quickly. The following code fragment will display the named styles, and therefore the CSS rules contained.

   
   import java.util.*;
   import javax.swing.text.*;
   import javax.swing.text.html.*;
   
   public class ShowStyles {
   
       public static void main(String[] args) {
           HTMLEditorKit kit = new HTMLEditorKit();
           HTMLDocument doc = (HTMLDocument) kit.createDefaultDocument();
           StyleSheet styles = doc.getStyleSheet();
           
           Enumeration rules = styles.getStyleNames();
           while (rules.hasMoreElements()) {
               String name = (String) rules.nextElement();
               Style rule = styles.getStyle(name);
               System.out.println(rule.toString());
           }
           System.exit(0);
       }
   }

The semantics for when a CSS style should overide visual attributes defined by an element are not well defined. For example, the html <body bgcolor=red> makes the body have a red background. But if the html file also contains the CSS rule body { background: blue } it becomes less clear as to what color the background of the body should be. The current implemention gives visual attributes defined in the element the highest precedence, that is they are always checked before any styles. Therefore, in the previous example the background would have a red color as the body element defines the background color to be red.

As already mentioned this supports CSS. We don't support the full CSS spec. Refer to the javadoc of the CSS class to see what properties we support. The two major CSS parsing related concepts we do not currently support are pseudo selectors, such as A:link { color: red }, and the important modifier.

Note: This implementation is currently incomplete. It can be replaced with alternative implementations that are complete. Future versions of this class will provide better CSS support.

See also:

Methods

Hide/Show inherited methods

public AttributeSet addAttribute (AttributeSet old, Object key, Object value) [Overrides StyleContext]

Adds an attribute to the given set, and returns the new representative set.

public AttributeSet addAttributes (AttributeSet old, AttributeSet attr) [Overrides StyleContext]

Adds a set of attributes to the element.

public void addChangeListener (ChangeListener l) [Inherited From StyleContext]

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

public void addCSSAttribute (MutableAttributeSet attr, Attribute key, String value)

Adds a CSS attribute to the given set.

public boolean addCSSAttributeFromHTML (MutableAttributeSet attr, Attribute key, String value)

Adds a CSS attribute to the given set.

public void addRule (String rule)

Adds a set of rules to the sheet.

pack-private void addRule (String selector, AttributeSet declaration, boolean isLinked)

Adds a rule into the StyleSheet.

public Style addStyle (String nm, Style parent) [Inherited From StyleContext]

Adds a new style into the style hierarchy.

public void addStyleSheet (StyleSheet ss)

Adds the rules from the StyleSheet ss to those of the receiver.

Adds the rules from the StyleSheet ss to those of
the receiver. ss's rules will override the rules of
any previously added style sheets. An added StyleSheet will never
override the rules of the receiving style sheet.
Since: 1.3

pack-private String cleanSelectorString (String selector)

Returns a string that only has one space between simple selectors, which may be the passed in String.

pack-private AttributeSet convertAttributeSet (AttributeSet a)

Converts a set of attributes (if necessary) so that any attributes that were specified as StyleConstants attributes and have a CSS mapping, will be converted to CSS attributes.

protected MutableAttributeSet createLargeAttributeSet (AttributeSet a) [Overrides StyleContext]

Creates a large set of attributes that should trade off space for time.

protected SmallAttributeSet createSmallAttributeSet (AttributeSet a) [Overrides StyleContext]

Creates a compact set of attributes that might be shared.

public Color getBackground (AttributeSet a) [Overrides StyleContext]

Takes a set of attributes and turn it into a background color specification.

pack-private ImageIcon getBackgroundImage (AttributeSet attr)

Returns the ImageIcon to draw in the background for attr.

public URL getBase ()

Returns the base.

public BoxPainter getBoxPainter (AttributeSet a)

Fetches the box formatter to use for the given set of CSS attributes.

public ChangeListener getChangeListeners () [Inherited From StyleContext]

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

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

protected int getCompressionThreshold () [Inherited From StyleContext]

Returns the maximum number of key/value pairs to try and compress into unique/immutable sets.

public AttributeSet getDeclaration (String decl)

Translates a CSS declaration to an AttributeSet that represents the CSS declaration.

publicfinalstatic StyleContext getDefaultStyleContext () [Inherited From StyleContext]

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

public AttributeSet getEmptySet () [Inherited From StyleContext]

Fetches an empty AttributeSet.

public Font getFont (AttributeSet a) [Overrides StyleContext]

Fetches the font to use for the given set of attributes.

public Font getFont (String family, int style, int size) [Inherited From StyleContext]

Gets a new font.

public FontMetrics getFontMetrics (Font f) [Inherited From StyleContext]

Returns font metrics for a font.

public Color getForeground (AttributeSet a) [Overrides StyleContext]

Takes a set of attributes and turn it into a foreground color specification.

publicstatic int getIndexOfSize (float pt)

public ListPainter getListPainter (AttributeSet a)

Fetches the list formatter to use for the given set of CSS attributes.

public float getPointSize (int index)

Returns the point size, given a size index.

public float getPointSize (String size)

Given a string such as "+2", "-2", or "2", returns a point size value.

public Style getRule (Tag t, Element e)

Fetches the style to use to render the given type of HTML tag.

public Style getRule (String selector)

Fetches the rule that best matches the selector given in string form.

Fetches the rule that best matches the selector given in string form. Where selector is a space separated String of the element names. For example, selector might be 'html body tr td''

The attributes of the returned Style will change as rules are added and removed. That is if you to ask for a rule with a selector "table p" and a new rule was added with a selector of "p" the returned Style would include the new attributes from the rule "p".

pack-private String getSimpleSelectors (String selector)

Returns the simple selectors that comprise selector.

pack-private int getSizeMap ()

pack-privatestatic int getSpecificity (String selector)

Returns the specificity of the passed in String.

publicstatic Object getStaticAttribute (Object key) [Inherited From StyleContext]

Returns the object previously registered with registerStaticAttributeKey.

publicstatic Object getStaticAttributeKey (Object key) [Inherited From StyleContext]

Returns the String that key will be registered with

Returns the String that key will be registered with
See Also: StyleContext.getStaticAttribute(java.lang.Object), StyleContext.registerStaticAttributeKey(java.lang.Object),

public Style getStyle (String nm) [Inherited From StyleContext]

Fetches a named style previously added to the document

public Enumeration<Object> getStyleNames () [Inherited From StyleContext]

Fetches the names of the styles defined.

public StyleSheet getStyleSheets ()

Returns an array of the linked StyleSheets.

public AttributeSet getViewAttributes (View v)

Fetches a set of attributes to use in the view for displaying.

public void importStyleSheet (URL url)

Imports a style sheet from url.

Imports a style sheet from url. The resulting rules
are directly added to the receiver. If you do not want the rules
to become part of the receiver, create a new StyleSheet and use
addStyleSheet to link it in.
Since: 1.3

pack-private boolean isW3CLengthUnits ()

public void loadRules (Reader in, URL ref) throws IOException

Loads a set of rules that have been specified in terms of CSS1 grammar.

public void readAttributes (ObjectInputStream in, MutableAttributeSet a) throws ClassNotFoundException IOException [Inherited From StyleContext]

Context-specific handling of reading in attributes

publicstatic void readAttributeSet (ObjectInputStream in, MutableAttributeSet a) throws ClassNotFoundException IOException [Inherited From StyleContext]

Reads a set of attributes from the given object input stream that have been previously written out with writeAttributeSet.

Reads a set of attributes from the given object input
stream that have been previously written out with
writeAttributeSet. This will try to restore
keys that were static objects to the static objects in
the current virtual machine considering only those keys
that have been registered with the
registerStaticAttributeKey method.
The attributes retrieved from the stream will be placed
into the given mutable set.
Parameters:
- in - the object stream to read the attribute data from.
- a - the attribute set to place the attribute definitions in.
Throws:
- ClassNotFoundException - passed upward if encountered when reading the object stream.
- IOException - passed upward if encountered when reading the object stream.

pack-private void rebaseSizeMap (int base)

public void reclaim (AttributeSet a) [Inherited From StyleContext]

Returns a set no longer needed by the MutableAttributeSet implmentation.

publicstatic void registerStaticAttributeKey (Object key) [Inherited From StyleContext]

Registers an object as a static object that is being used as a key in attribute sets.

public AttributeSet removeAttribute (AttributeSet old, Object key) [Overrides StyleContext]

Removes an attribute from the set.

public AttributeSet removeAttributes (AttributeSet old, AttributeSet attrs) [Overrides StyleContext]

Removes a set of attributes.

public AttributeSet removeAttributes (AttributeSet old, Enumeration<Object> names) [Overrides StyleContext]

Removes a set of attributes for the element.

public void removeChangeListener (ChangeListener l) [Inherited From StyleContext]

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

public void removeStyle (String nm) [Overrides StyleContext]

Removes a named style previously added to the document.

public void removeStyleSheet (StyleSheet ss)

Removes the StyleSheet ss from those of the receiver.

Removes the StyleSheet ss from those of the receiver.
Since: 1.3

public void setBase (URL base)

Sets the base.

Sets the base. All import statements that are relative, will be
relative to base.
Since: 1.3

public void setBaseFontSize (int sz)

Sets the base font size, with valid values between 1 and 7.

public void setBaseFontSize (String size)

Sets the base font size from the passed in String.

public Color stringToColor (String string)

Converts a color string such as "RED" or "#NNNNNN" to a Color.

public String toString () [Inherited From StyleContext]

Converts a StyleContext to a String.

public AttributeSet translateHTMLToCSS (AttributeSet htmlAttrSet)

Converts a set of HTML attributes to an equivalent set of CSS attributes.

public void writeAttributes (ObjectOutputStream out, AttributeSet a) throws IOException [Inherited From StyleContext]

Context-specific handling of writing out attributes

publicstatic void writeAttributeSet (ObjectOutputStream out, AttributeSet a) throws IOException [Inherited From StyleContext]

Writes a set of attributes to the given object stream for the purpose of serialization.

Writes a set of attributes to the given object stream
for the purpose of serialization. This will take
special care to deal with static attribute keys that
have been registered wit the
registerStaticAttributeKey method.
Any attribute key not regsitered as a static key
will be serialized directly. All values are expected
to be serializable.
Parameters:
- out - the output stream
- a - the attribute set
Throws:
- IOException - on any I/O error