accessiblehtml.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

/*
 * @(#)AccessibleHTML.java	1.15 06/04/07
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.swing.text.html;

import java.awt.*;
import java.awt.event.*;
import java.beans.*; 
import java.util.*; 
import javax.swing.*;
import javax.swing.event.*;  
import javax.swing.text.*; 
import javax.accessibility.*;
import java.text.BreakIterator;

/*
 * The AccessibleHTML class provide information about the contents 
 * of a HTML document to assistive technologies.
 * 
 * @version 1.15 04/07/06
 * @author  Lynn Monsanto
 */
class AccessibleHTML implements Accessible {

    /**
     * The editor.
     */
    private JEditorPane editor;
    /**
     * Current model.
     */
    private Document model;
    /**
     * DocumentListener installed on the current model.
     */
    private DocumentListener docListener;
    /**
     * PropertyChangeListener installed on the editor
     */
    private PropertyChangeListener propChangeListener;
    /**
     * The root ElementInfo for the document
     */
    private ElementInfo rootElementInfo;
    /*
     * The root accessible context for the document
     */
    private RootHTMLAccessibleContext rootHTMLAccessibleContext;

    public AccessibleHTML(JEditorPane pane) {
	editor = pane;
	propChangeListener = new PropertyChangeHandler();
        setDocument(editor.getDocument());

        docListener = new DocumentHandler();
    }

    /**
     * Sets the document.
     */
    private void setDocument(Document document) {
        if (model != null) {
            model.removeDocumentListener(docListener);
        }
	if (editor != null) {
	    editor.removePropertyChangeListener(propChangeListener);
	}
        this.model = document;
        if (model != null) {
            if (rootElementInfo != null) {
                rootElementInfo.invalidate(false);
            }
            buildInfo();
            model.addDocumentListener(docListener);
        }
        else {
            rootElementInfo = null;
        }
	if (editor != null) {
	    editor.addPropertyChangeListener(propChangeListener);
	}
    }

    /**
     * Returns the Document currently presenting information for.
     */
    private Document getDocument() {
        return model;
    }

    /**
     * Returns the JEditorPane providing information for.
     */
    private JEditorPane getTextComponent() {
        return editor;
    }

    /**
     * Returns the ElementInfo representing the root Element.
     */
    private ElementInfo getRootInfo() {
        return rootElementInfo;
    }

    /**
     * Returns the root <code>View</code> associated with the current text
     * component.
     */
    private View getRootView() {
        return getTextComponent().getUI().getRootView(getTextComponent());
    }

    /**
     * Returns the bounds the root View will be rendered in.
     */
    private Rectangle getRootEditorRect() {
        Rectangle alloc = getTextComponent().getBounds();
        if ((alloc.width > 0) && (alloc.height > 0)) {
            alloc.x = alloc.y = 0;
            Insets insets = editor.getInsets();
            alloc.x += insets.left;
            alloc.y += insets.top;
            alloc.width -= insets.left + insets.right;
            alloc.height -= insets.top + insets.bottom;
            return alloc;
        }
        return null;
    }

    /**
     * If possible acquires a lock on the Document.  If a lock has been
     * obtained a key will be retured that should be passed to
     * <code>unlock</code>.
     */
    private Object lock() {
        Document document = getDocument();

        if (document instanceof AbstractDocument) {
            ((AbstractDocument)document).readLock();
            return document;
        }
        return null;
    }

    /**
     * Releases a lock previously obtained via <code>lock</code>.
     */
    private void unlock(Object key) {
        if (key != null) {
            ((AbstractDocument)key).readUnlock();
        }
    }

    /**
     * Rebuilds the information from the current info.
     */
    private void buildInfo() {
        Object lock = lock();

        try {
            Document doc = getDocument();
            Element root = doc.getDefaultRootElement();

            rootElementInfo = new ElementInfo(root);
            rootElementInfo.validate();
        } finally {
            unlock(lock);
        }
    }

    /*
     * Create an ElementInfo subclass based on the passed in Element.
     */
    ElementInfo createElementInfo(Element e, ElementInfo parent) {
        AttributeSet attrs = e.getAttributes();

        if (attrs != null) {
            Object name = attrs.getAttribute(StyleConstants.NameAttribute);

            if (name == HTML.Tag.IMG) {
                return new IconElementInfo(e, parent);
            }
            else if (name == HTML.Tag.CONTENT || name == HTML.Tag.CAPTION) {
                return new TextElementInfo(e, parent);
            }
            else if (name == HTML.Tag.TABLE) {
                return new TableElementInfo(e, parent);
            }
        }
        return null;
    }
    
    /**
     * Returns the root AccessibleContext for the document
     */
    public AccessibleContext getAccessibleContext() {
	if (rootHTMLAccessibleContext == null) {
	    rootHTMLAccessibleContext = 
		new RootHTMLAccessibleContext(rootElementInfo);
	}
	return rootHTMLAccessibleContext;
    }
    
    /*
     * The roow AccessibleContext for the document
     */
    private class RootHTMLAccessibleContext extends HTMLAccessibleContext {

	public RootHTMLAccessibleContext(ElementInfo elementInfo) {
	    super(elementInfo);
	}

	/**
	 * Gets the accessibleName property of this object.  The accessibleName
	 * property of an object is a localized String that designates the purpose
	 * of the object.  For example, the accessibleName property of a label
	 * or button might be the text of the label or button itself.  In the
	 * case of an object that doesn't display its name, the accessibleName
	 * should still be set.  For example, in the case of a text field used
	 * to enter the name of a city, the accessibleName for the en_US locale
	 * could be 'city.'
	 *
	 * @return the localized name of the object; null if this 
	 * object does not have a name
	 *
	 * @see #setAccessibleName
	 */
	public String getAccessibleName() {
	    if (model != null) {
		return (String)model.getProperty(Document.TitleProperty);
	    } else {
		return null;
	    }
	}
	
	/**
	 * Gets the accessibleDescription property of this object.  If this
	 * property isn't set, returns the content type of this
	 * <code>JEditorPane</code> instead (e.g. "plain/text", "html/text").
	 *
	 * @return the localized description of the object; <code>null</code>
	 * 	if this object does not have a description
	 *
	 * @see #setAccessibleName
	 */
	public String getAccessibleDescription() {
	    return editor.getContentType();
	}
	
	/**
	 * Gets the role of this object.  The role of the object is the generic
	 * purpose or use of the class of this object.  For example, the role
	 * of a push button is AccessibleRole.PUSH_BUTTON.  The roles in 
	 * AccessibleRole are provided so component developers can pick from
	 * a set of predefined roles.  This enables assistive technologies to
	 * provide a consistent interface to various tweaked subclasses of 
	 * components (e.g., use AccessibleRole.PUSH_BUTTON for all components
	 * that act like a push button) as well as distinguish between sublasses
	 * that behave differently (e.g., AccessibleRole.CHECK_BOX for check boxes
	 * and AccessibleRole.RADIO_BUTTON for radio buttons).
	 * <p>Note that the AccessibleRole class is also extensible, so 
	 * custom component developers can define their own AccessibleRole's
	 * if the set of predefined roles is inadequate.
	 *
	 * @return an instance of AccessibleRole describing the role of the object
	 * @see AccessibleRole
	 */
	public AccessibleRole getAccessibleRole() {
	    return AccessibleRole.TEXT;
	}
    }

    /*
     * Base AccessibleContext class for HTML elements
     */
    protected abstract class HTMLAccessibleContext extends AccessibleContext
        implements Accessible, AccessibleComponent {

	protected ElementInfo elementInfo;

	public HTMLAccessibleContext(ElementInfo elementInfo) {
	    this.elementInfo = elementInfo;
	}

	// begin AccessibleContext implementation ...
	public AccessibleContext getAccessibleContext() {
	    return this;
	}

	/**
	 * Gets the state set of this object.
	 *
	 * @return an instance of AccessibleStateSet describing the states
	 * of the object
	 * @see AccessibleStateSet
	 */
	public AccessibleStateSet getAccessibleStateSet() {
	    AccessibleStateSet states = new AccessibleStateSet();
	    Component comp = getTextComponent();

	    if (comp.isEnabled()) {
		states.add(AccessibleState.ENABLED);
	    }
	    if (comp instanceof JTextComponent &&
		((JTextComponent)comp).isEditable()) {
		
		states.add(AccessibleState.EDITABLE);
		states.add(AccessibleState.FOCUSABLE);
	    }
	    if (comp.isVisible()) {
		states.add(AccessibleState.VISIBLE);
	    }
	    if (comp.isShowing()) {
		states.add(AccessibleState.SHOWING);
	    }
	    return states;
	}
	
	/**
	 * Gets the 0-based index of this object in its accessible parent.
	 *
	 * @return the 0-based index of this object in its parent; -1 if this 
	 * object does not have an accessible parent.
	 *
	 * @see #getAccessibleParent 
	 * @see #getAccessibleChildrenCount
	 * @see #getAccessibleChild
	 */
	public int getAccessibleIndexInParent() {
	    return elementInfo.getIndexInParent();
	}
	
	/**
	 * Returns the number of accessible children of the object.
	 *
	 * @return the number of accessible children of the object.
	 */
	public int getAccessibleChildrenCount() {
	    return elementInfo.getChildCount();
	}
	
	/**
	 * Returns the specified Accessible child of the object.  The Accessible
	 * children of an Accessible object are zero-based, so the first child 
	 * of an Accessible child is at index 0, the second child is at index 1,
	 * and so on.
	 *
	 * @param i zero-based index of child
	 * @return the Accessible child of the object
	 * @see #getAccessibleChildrenCount
	 */
	public Accessible getAccessibleChild(int i) {
	    ElementInfo childInfo = elementInfo.getChild(i);
	    if (childInfo != null && childInfo instanceof Accessible) {
		return (Accessible)childInfo;
	    } else {
		return null;
	    }
	}
	
	/** 
	 * Gets the locale of the component. If the component does not have a 
	 * locale, then the locale of its parent is returned.  
	 *
	 * @return this component's locale.  If this component does not have 
	 * a locale, the locale of its parent is returned.
	 *
	 * @exception IllegalComponentStateException 
	 * If the Component does not have its own locale and has not yet been 
	 * added to a containment hierarchy such that the locale can be
	 * determined from the containing parent. 
	 */
	public Locale getLocale() throws IllegalComponentStateException {
	    return editor.getLocale();
	}
	// ... end AccessibleContext implementation

	// begin AccessibleComponent implementation ...
	public AccessibleComponent getAccessibleComponent() {
	    return this;
	}
	
	/**
	 * Gets the background color of this object.
	 *
	 * @return the background color, if supported, of the object; 
	 * otherwise, null
	 * @see #setBackground
	 */
	public Color getBackground() {
	    return getTextComponent().getBackground();
	}
	
	/**
	 * Sets the background color of this object.
	 *
	 * @param c the new Color for the background
	 * @see #setBackground
	 */
	public void setBackground(Color c) {
	    getTextComponent().setBackground(c);
	}
	
	/**
	 * Gets the foreground color of this object.
	 *
	 * @return the foreground color, if supported, of the object; 
	 * otherwise, null
	 * @see #setForeground
	 */
	public Color getForeground() {
	    return getTextComponent().getForeground();
	}
	
	/**
	 * Sets the foreground color of this object.
	 *
	 * @param c the new Color for the foreground
	 * @see #getForeground
	 */
	public void setForeground(Color c) {
	    getTextComponent().setForeground(c);
	}
	
	/**
	 * Gets the Cursor of this object.
	 *
	 * @return the Cursor, if supported, of the object; otherwise, null
	 * @see #setCursor
	 */
	public Cursor getCursor() {
	    return getTextComponent().getCursor();
	}
	
	/**
	 * Sets the Cursor of this object.
	 *
	 * @param c the new Cursor for the object
	 * @see #getCursor
	 */
	public void setCursor(Cursor cursor) {