stylesheet.java

JAVA 所有包

/*
 * @(#)StyleSheet.java	1.91 05/11/30
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing.text.html;

import sun.swing.SwingUtilities2;
import java.util.*;
import java.awt.*;
import java.io.*;
import java.net.*;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.border.*;
import javax.swing.event.ChangeListener;
import javax.swing.text.*;

/**
 * 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
 * <code>toString</code> method is required
 * to return a string representation of CSS value.
 * <p>
 * The primary entry point for HTML View implementations
 * to get their attributes is the 
 * <a href="#getViewAttributes">getViewAttributes</a>
 * 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.
 * <p>
 * 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.
 * <p>
 * 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.
 * <code><pre>
 * &nbsp; 
 * &nbsp; import java.util.*;
 * &nbsp; import javax.swing.text.*;
 * &nbsp; import javax.swing.text.html.*;
 * &nbsp; 
 * &nbsp; public class ShowStyles {
 * &nbsp; 
 * &nbsp;     public static void main(String[] args) {
 * &nbsp; 	HTMLEditorKit kit = new HTMLEditorKit();
 * &nbsp; 	HTMLDocument doc = (HTMLDocument) kit.createDefaultDocument();
 * &nbsp; 	StyleSheet styles = doc.getStyleSheet();
 * &nbsp; 	
 * &nbsp; 	Enumeration rules = styles.getStyleNames();
 * &nbsp; 	while (rules.hasMoreElements()) {
 * &nbsp; 	    String name = (String) rules.nextElement();
 * &nbsp; 	    Style rule = styles.getStyle(name);
 * &nbsp; 	    System.out.println(rule.toString());
 * &nbsp; 	}
 * &nbsp; 	System.exit(0);
 * &nbsp;     }
 * &nbsp; }
 * &nbsp; 
 * </pre></code>
 * <p>
 * The semantics for when a CSS style should overide visual attributes
 * defined by an element are not well defined. For example, the html
 * <code>&lt;body bgcolor=red&gt;</code> makes the body have a red
 * background. But if the html file also contains the CSS rule
 * <code>body { background: blue }</code> 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.
 * <p>
 * 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 <code>A:link { color: red }</code>,
 * and the <code>important</code> modifier.
 * <p>
 * <font color="red">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.</font>
 *
 * @author  Timothy Prinzing
 * @author  Sunita Mani
 * @author  Sara Swanson
 * @author  Jill Nakata
 * @version 1.91 11/30/05
 */
public class StyleSheet extends StyleContext {
    // As the javadoc states, this class maintains a mapping between
    // a CSS selector (such as p.bar) and a Style.
    // This consists of a number of parts:
    // . Each selector is broken down into its constituent simple selectors,
    //   and stored in an inverted graph, for example:
    //     p { color: red } ol p { font-size: 10pt } ul p { font-size: 12pt }
    //   results in the graph:
    //          root
    //           |
    //           p
    //          / \
    //         ol ul
    //   each node (an instance of SelectorMapping) has an associated
    //   specificity and potentially a Style.
    // . Every rule that is asked for (either by way of getRule(String) or
    //   getRule(HTML.Tag, Element)) results in a unique instance of
    //   ResolvedStyle. ResolvedStyles contain the AttributeSets from the
    //   SelectorMapping.
    // . When a new rule is created it is inserted into the graph, and
    //   the AttributeSets of each ResolvedStyles are updated appropriately.
    // . This class creates special AttributeSets, LargeConversionSet and
    //   SmallConversionSet, that maintain a mapping between StyleConstants
    //   and CSS so that developers that wish to use the StyleConstants
    //   methods can do so.
    // . When one of the AttributeSets is mutated by way of a
    //   StyleConstants key, all the associated CSS keys are removed. This is
    //   done so that the two representations don't get out of sync. For
    //   example, if the developer adds StyleConsants.BOLD, FALSE to an
    //   AttributeSet that contains HTML.Tag.B, the HTML.Tag.B entry will
    //   be removed.

    /**
     * Construct a StyleSheet
     */
    public StyleSheet() {
	super();
	selectorMapping = new SelectorMapping(0);
	resolvedStyles = new Hashtable();
	if (css == null) {
	    css = new CSS();
	}
    }

    /**
     * Fetches 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.
     *
     * @param t the type to translate to visual attributes
     * @param 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
     * @return the set of CSS attributes to use to render
     *  the tag
     */
    public Style getRule(HTML.Tag t, Element e) {
        SearchBuffer sb = SearchBuffer.obtainSearchBuffer();

        try {
            // Build an array of all the parent elements.
            Vector searchContext = sb.getVector();

            for (Element p = e; p != null; p = p.getParentElement()) {
                searchContext.addElement(p);
            }

            // Build a fully qualified selector.
            int              n = searchContext.size();
            StringBuffer     cacheLookup = sb.getStringBuffer();
            AttributeSet     attr;
            String           eName;
            Object           name;

            // >= 1 as the HTML.Tag for the 0th element is passed in.
            for (int counter = n - 1; counter >= 1; counter--) {
                e = (Element)searchContext.elementAt(counter);
                attr = e.getAttributes();
                name = attr.getAttribute(StyleConstants.NameAttribute);
		eName = name.toString();
                cacheLookup.append(eName);
                if (attr != null) {
                    if (attr.isDefined(HTML.Attribute.ID)) {
                        cacheLookup.append('#');
                        cacheLookup.append(attr.getAttribute
					   (HTML.Attribute.ID));
                    }
                    else if (attr.isDefined(HTML.Attribute.CLASS)) {
                        cacheLookup.append('.');
                        cacheLookup.append(attr.getAttribute
					   (HTML.Attribute.CLASS));
                    }
                }
                cacheLookup.append(' ');
            }
            cacheLookup.append(t.toString());
	    e = (Element)searchContext.elementAt(0);
	    attr = e.getAttributes();
	    if (e.isLeaf()) {
		// For leafs, we use the second tier attributes.
		Object testAttr = attr.getAttribute(t);
		if (testAttr instanceof AttributeSet) {
		    attr = (AttributeSet)testAttr;
		}
		else {
		    attr = null;
		}
	    }
            if (attr != null) {
                if (attr.isDefined(HTML.Attribute.ID)) {
                    cacheLookup.append('#');
                    cacheLookup.append(attr.getAttribute(HTML.Attribute.ID));
                }
                else if (attr.isDefined(HTML.Attribute.CLASS)) {
                    cacheLookup.append('.');
                    cacheLookup.append(attr.getAttribute
				       (HTML.Attribute.CLASS));
                }
            }

            Style style = getResolvedStyle(cacheLookup.toString(),
					   searchContext, t);
	    return style;
        }
        finally {
            SearchBuffer.releaseSearchBuffer(sb);
        }
    }

    /**
     * Fetches the rule that best matches the selector given
     * in string form. Where <code>selector</code> is a space separated
     * String of the element names. For example, <code>selector</code>
     * might be 'html body tr td''<p>
     * 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".
     */
    public Style getRule(String selector) {
	selector = cleanSelectorString(selector);
	if (selector != null) {
	    Style style = getResolvedStyle(selector);
	    return style;
	}
	return null;
    }

    /**
     * Adds 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 &lt;style&gt; tag.
     */
    public void addRule(String rule) {
	if (rule != null) {
            //tweaks to control display properties
            //see BasicEditorPaneUI
            final String baseUnitsDisable = "BASE_SIZE_DISABLE";
            final String baseUnits = "BASE_SIZE ";
            final String w3cLengthUnitsEnable = "W3C_LENGTH_UNITS_ENABLE";
            final String w3cLengthUnitsDisable = "W3C_LENGTH_UNITS_DISABLE";
            if (rule == baseUnitsDisable) {
                sizeMap = sizeMapDefault;
            } else if (rule.startsWith(baseUnits)) {
                rebaseSizeMap(Integer.
                              parseInt(rule.substring(baseUnits.length())));
            } else if (rule == w3cLengthUnitsEnable) {
                w3cLengthUnits = true;
            } else if (rule == w3cLengthUnitsDisable) {
                w3cLengthUnits = false;
            } else {
                CssParser parser = new CssParser();
                try {
                    parser.parse(getBase(), new StringReader(rule), false, false);
                } catch (IOException ioe) { }
            }
	}
    }

    /**
     * Translates 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.
     */
    public AttributeSet getDeclaration(String decl) {
	if (decl == null) {
	    return SimpleAttributeSet.EMPTY;
	}
	CssParser parser = new CssParser();
	return parser.parseDeclaration(decl);
    }

    /**
     * Loads 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.
     *
     * @param in the stream to read the CSS grammar from
     * @param 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.
     */
    public void loadRules(Reader in, URL ref) throws IOException {
	CssParser parser = new CssParser();
	parser.parse(ref, in, false, false);
    }

    /**
     * Fetches 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.
     */
    public AttributeSet getViewAttributes(View v) {
	return new ViewAttributeSet(v);
    }

    /**
     * Removes a named style previously added to the document.
     *
     * @param nm  the name of the style to remove
     */
    public void removeStyle(String nm) {
	Style       aStyle = getStyle(nm);

	if (aStyle != null) {
	    String selector = cleanSelectorString(nm);
	    String[] selectors = getSimpleSelectors(selector);
	    synchronized(this) {
		SelectorMapping mapping = getRootSelectorMapping();
		for (int i = selectors.length - 1; i >= 0; i--) {
		    mapping = mapping.getChildSelectorMapping(selectors[i],
                                                              true);
		}
		Style rule = mapping.getStyle();
		if (rule != null) {
		    mapping.setStyle(null);
		    if (resolvedStyles.size() > 0) {
			Enumeration values = resolvedStyles.elements();
			while (values.hasMoreElements()) {
			    ResolvedStyle style = (ResolvedStyle)values.
				                    nextElement();
			    style.removeStyle(rule);
			}
		    }
		}
	    }
	}
	super.removeStyle(nm);
    }

    /**
     * Adds the rules from the StyleSheet <code>ss</code> to those of
     * the receiver. <code>ss's</code> 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
     */
    public void addStyleSheet(StyleSheet ss) {
	synchronized(this) {
	    if (linkedStyleSheets == null) {
		linkedStyleSheets = new Vector();
	    }
	    if (!linkedStyleSheets.contains(ss)) {
                int index = 0;
                if (ss instanceof javax.swing.plaf.UIResource
                    && linkedStyleSheets.size() > 1) {
                    index = linkedStyleSheets.size() - 1;
                }
		linkedStyleSheets.insertElementAt(ss, index);
		linkStyleSheetAt(ss, index);
	    }
	}
    }

    /**
     * Removes the StyleSheet <code>ss</code> from those of the receiver.
     *
     * @since 1.3