javax.swing.text.html
Class StyleSheet

java.lang.Object
  |
  +--javax.swing.text.StyleContext
        |
        +--javax.swing.text.html.StyleSheet
All Implemented Interfaces:
AbstractDocument.AttributeContext, Serializable
public class StyleSheet
extends StyleContext

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.

 

Nested Class Summary

static class StyleSheet.BoxPainter
    Class to carry out some of the duties of CSS formatting.
static class StyleSheet.ListPainter
    Class to carry out some of the duties of CSS list formatting.
 
Nested classes inherited from class javax.swing.text.StyleContext
StyleContext.NamedStyle, StyleContext.SmallAttributeSet
 

 

Field Summary

 
Fields inherited from class javax.swing.text.StyleContext
DEFAULT_STYLE
 

 

Constructor Summary

StyleSheet()
    Construct a StyleSheet
 

 

Method Summary

 AttributeSet addAttribute(AttributeSet old, Object key, 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 addCSSAttribute(MutableAttributeSet attr, CSS.Attribute key, String value)
    Adds a CSS attribute to the given set.
 boolean addCSSAttributeFromHTML(MutableAttributeSet attr, CSS.Attribute key, String value)
    Adds a CSS attribute to the given set.
 void addRule(String rule)
    Adds a set of rules to the sheet.
 void addStyleSheet(StyleSheet ss)
    Adds the rules from the StyleSheet ss to those of the receiver.
protected  MutableAttributeSet createLargeAttributeSet(AttributeSet a)
    Creates a large set of attributes that should trade off space for time.
protected  StyleContext.SmallAttributeSet createSmallAttributeSet(AttributeSet a)
    Creates a compact set of attributes that might be shared.
 Color getBackground(AttributeSet a)
    Takes a set of attributes and turn it into a background color specification.
 URL getBase()
    Returns the base.
 StyleSheet.BoxPainter getBoxPainter(AttributeSet a)
    Fetches the box formatter to use for the given set of CSS attributes.
 AttributeSet getDeclaration(String decl)
    Translates a CSS declaration to an AttributeSet that represents the CSS declaration.
 Font getFont(AttributeSet a)
    Fetches the font to use for the given set of attributes.
 Color getForeground(AttributeSet a)
    Takes a set of attributes and turn it into a foreground color specification.
static int getIndexOfSize(float pt)
    
 StyleSheet.ListPainter getListPainter(AttributeSet a)
    Fetches the list formatter to use for the given set of CSS attributes.
 float getPointSize(int index)
    Returns the point size, given a size index.
 float getPointSize(String size)
    Given a string such as "+2", "-2", or "2", returns a point size value.
 Style getRule(HTML.Tag t, Element e)
    Fetches the style to use to render the given type of HTML tag.
 Style getRule(String selector)
    Fetches the rule that best matches the selector given in string form.
 StyleSheet[] getStyleSheets()
    Returns an array of the linked StyleSheets.
 AttributeSet getViewAttributes(View v)
    Fetches a set of attributes to use in the view for displaying.
 void importStyleSheet(URL url)
    Imports a style sheet from url.
 void loadRules(Reader in, URL ref)
    Loads a set of rules that have been specified in terms of CSS1 grammar.
 AttributeSet removeAttribute(AttributeSet old, Object key)
    Removes an attribute from the set.
 AttributeSet removeAttributes(AttributeSet old, AttributeSet attrs)
    Removes a set of attributes.
 AttributeSet removeAttributes(AttributeSet old, Enumeration names)
    Removes a set of attributes for the element.
 void removeStyle(String nm)
    Removes a named style previously added to the document.
 void removeStyleSheet(StyleSheet ss)
    Removes the StyleSheet ss from those of the receiver.
 void setBase(URL base)
    Sets the base.
 void setBaseFontSize(int sz)
    Sets the base font size, with valid values between 1 and 7.
 void setBaseFontSize(String size)
    Sets the base font size from the passed in String.
 Color stringToColor(String string)
    Converts a color string such as "RED" or "#NNNNNN" to a Color.
 AttributeSet translateHTMLToCSS(AttributeSet htmlAttrSet)
    Converts a set of HTML attributes to an equivalent set of CSS attributes.
 
Methods inherited from class javax.swing.text.StyleContext
addChangeListener, addStyle, getChangeListeners, getCompressionThreshold, getDefaultStyleContext, getEmptySet, getFont, getFontMetrics, getStaticAttribute, getStaticAttributeKey, getStyle, getStyleNames, readAttributes, readAttributeSet, reclaim, registerStaticAttributeKey,