javax.swing.text.html
Class StyleSheet

java.lang.Object
  |
  +--javax.swing.text.StyleContext
        |
        +--javax.swing.text.html.StyleSheet

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);
       }
   }
   
 

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:

Serialized Form

Inner 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.

Inner classes inherited from class javax.swing.text.StyleContext

StyleContext.NamedStyle, StyleContext.SmallAttributeSet

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	addRule(String rule) Add a set of rules to the sheet.
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 a) Takes a set of attributes and turn it into a background color specification.
StyleSheet.BoxPainter	getBoxPainter(AttributeSet a) Fetch the box formatter to use for the given set of css attributes.
AttributeSet	getDeclaration(String decl) Translate a CSS declaration to an AttributeSet that represents the CSS declaration.
Font	getFont(AttributeSet a) Fetch 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) Fetch the list formatter to use for the given set of css attributes.
float	getPointSize(int index) Return the point size, given a size index.
float	getPointSize(String size) Given a string "+2", "-2", "2".
Style	getRule(HTML.Tag t, Element e) Fetch the style to use to render the given type of html tag.
Style	getRule(String selector) Fetch the rule that best matches the selector given in string form.
AttributeSet	getViewAttributes(View v) Fetch a set of attributes to use in the view for displaying.
void	loadRules(Reader in, URL ref) Load 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	setBaseFontSize(int sz)
void	setBaseFontSize(String size)
Color	stringToColor(String string) Convert a color string "RED" or "#NNNNNN" to a Color.
AttributeSet	translateHTMLToCSS(AttributeSet htmlAttrSet) Convert a set of html attributes to an equivalent set of css attributes.

Methods inherited from class javax.swing.text.StyleContext

addChangeListener, addStyle, getCompressionThreshold, getDefaultStyleContext, getEmptySet, getFont, getFontMetrics, getStaticAttribute, getStaticAttributeKey, getStyle, getStyleNames, readAttributes, readAttributeSet, reclaim, registerStaticAttributeKey, removeChangeListener, toString, writeAttributes, writeAttributeSet

Methods inherited from class java.lang.Object

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

Constructor Detail

StyleSheet

public StyleSheet()

Construct a StyleSheet

Method Detail

getRule

public Style getRule(HTML.Tag t,
                     Element e)

Fetch the style to use to render the given type of html tag. The element given is representing the tag and can be used to determine the nesting for situations where the attributes will differ if nesting inside of elements.

Parameters:

t - the type to translate to visual attributes.

e - the element representing the tag. The element can be used to determine the nesting for situations where the attributes will differ if nested inside of other elements.

getRule

public Style getRule(String selector)

Fetch 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".

addRule

public void addRule(String rule)

Add a set of rules to the sheet. The rules are expected to be in valid CSS format. Typically this would be called as a result of parsing a <style> tag.

getDeclaration

public AttributeSet getDeclaration(String decl)

Translate a CSS declaration to an AttributeSet that represents the CSS declaration. Typically this would be called as a result of encountering an HTML style attribute.

loadRules

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

Load a set of rules that have been specified in terms of CSS1 grammar. If there are collisions with existing rules, the newly specified rule will win.

Parameters:

in - the stream to read the css grammar from.

ref - the reference url. This value represents the location of the stream and may be null. All relative urls specified in the stream will be based upon this parameter.

getViewAttributes

public AttributeSet getViewAttributes(View v)

Fetch a set of attributes to use in the view for displaying. This is basically a set of attributes that can be used for View.getAttributes.

removeStyle

public void removeStyle(String nm)

Removes a named style previously added to the document.

Overrides:

removeStyle in class StyleContext

Parameters:

nm - the name of the style to remove

translateHTMLToCSS

public AttributeSet translateHTMLToCSS(AttributeSet htmlAttrSet)

Convert a set of html attributes to an equivalent set of css attributes.

Parameters:

AttributeSet - containing the HTML attributes.

AttributeSet - containing the corresponding CSS attributes. The AttributeSet will be empty if there are no mapping CSS attributes.

addAttribute

public AttributeSet addAttribute(AttributeSet old,
                                 Object key,
                                 Object value)

Adds an attribute to the given set, and returns the new representative set. This is reimplemented to convert StyleConstant attributes to CSS prior to forwarding to the superclass behavior. The the StyleConstants attribute has no corresponding CSS entry, the StyleConstants attribute is stored (but will likely be unused).

Overrides:

addAttribute in class StyleContext

Parameters:

old - the old attribute set

key - the non-null attribute key

value - the attribute value

Returns:

the updated attribute set

See Also:

MutableAttributeSet.addAttribute(java.lang.Object, java.lang.Object)

addAttributes

public AttributeSet addAttributes(AttributeSet old,
                                  AttributeSet attr)

Adds a set of attributes to the element. If any of these attributes are StyleConstants attributes, they will be converted to CSS prior to forwarding to the superclass behavior.

Overrides:

addAttributes in class StyleContext

Parameters:

old - the old attribute set

attr - the attributes to add

Returns:

the updated attribute set

See Also:

MutableAttributeSet.addAttribute(java.lang.Object, java.lang.Object)

removeAttribute

public AttributeSet removeAttribute(AttributeSet old,
                                    Object key)

Removes an attribute from the set. If the attribute is a StyleConstants attribute, the request will be converted to a CSS attribute prior to forwarding to the superclass behavior.

Overrides:

removeAttribute in class StyleContext

Parameters:

old - the old set of attributes

key - the non-null attribute name

Returns:

the updated attribute set

See Also:

MutableAttributeSet.removeAttribute(java.lang.Object)

removeAttributes

public AttributeSet removeAttributes(AttributeSet old,
                                     Enumeration names)

Removes a set of attributes for the element. If any of the attributes is a StyleConstants attribute, the request will be converted to a CSS attribute prior to forwarding to the superclass behavior.

Overrides:

removeAttributes in class StyleContext

Parameters:

old - the old attribute set

names - the attribute names

Returns:

the updated attribute set

See Also:

MutableAttributeSet.removeAttributes(java.util.Enumeration)

removeAttributes

public AttributeSet removeAttributes(AttributeSet old,
                                     AttributeSet attrs)

Removes a set of attributes. If any of the attributes is a StyleConstants attribute, the request will be converted to a CSS attribute prior to forwarding to the superclass behavior.

Overrides:

removeAttributes in class StyleContext

Parameters:

old - the old attribute set

attrs - the attributes

Returns:

the updated attribute set

See Also:

MutableAttributeSet.removeAttributes(java.util.Enumeration)

createSmallAttributeSet

protected StyleContext.SmallAttributeSet createSmallAttributeSet(AttributeSet a)

Create a compact set of attributes that might be shared. This is a hook for subclasses that want to alter the behavior of SmallAttributeSet. This can be reimplemented to return an AttributeSet that provides some sort of attribute conversion.

Overrides:

createSmallAttributeSet in class StyleContext

Parameters:

a - The set of attributes to be represented in the the compact form.

createLargeAttributeSet

protected MutableAttributeSet createLargeAttributeSet(AttributeSet a)

Create a large set of attributes that should trade off space for time. This set will not be shared. This is a hook for subclasses that want to alter the behavior of the larger attribute storage format (which is SimpleAttributeSet by default). This can be reimplemented to return a MutableAttributeSet that provides some sort of attribute conversion.

Overrides:

createLargeAttributeSet in class StyleContext

Parameters:

a - The set of attributes to be represented in the the larger form.

getFont

public Font getFont(AttributeSet a)

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

Overrides:

getFont in class StyleContext

Tags copied from class: StyleContext

Parameters:

attr - the attribute set

Returns:

the font

getForeground

public Color getForeground(AttributeSet a)

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.

Overrides:

getForeground in class StyleContext

Parameters:

a - the set of attributes

Returns:

the color

getBackground

public Color getBackground(AttributeSet a)

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.

Overrides:

getBackground in class StyleContext

Parameters:

attr - the set of attributes

Returns:

the color

getBoxPainter

public StyleSheet.BoxPainter getBoxPainter(AttributeSet a)

Fetch the box formatter to use for the given set of css attributes.

getListPainter

public StyleSheet.ListPainter getListPainter(AttributeSet a)

Fetch the list formatter to use for the given set of css attributes.

setBaseFontSize

public void setBaseFontSize(int sz)

setBaseFontSize

public void setBaseFontSize(String size)

getIndexOfSize

public static int getIndexOfSize(float pt)

getPointSize

public float getPointSize(int index)

Return the point size, given a size index.

getPointSize

public float getPointSize(String size)

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

stringToColor

public Color stringToColor(String string)

Convert a color string "RED" or "#NNNNNN" to a Color. Note: This will only convert the HTML3.2 colors strings or string of length 7 otherwise, it will return null.