/*
 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */
package javax.swing.plaf.basic;

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.datatransfer.*;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.awt.im.InputContext;
import java.beans.*;
import java.io.*;
import javax.swing.*;
import javax.swing.plaf.*;
import javax.swing.text.*;
import javax.swing.event.*;
import javax.swing.border.Border;
import javax.swing.plaf.UIResource;
import javax.swing.plaf.synth.SynthUI;
import sun.swing.DefaultLookup;
import sun.awt.AppContext;
import sun.swing.SwingUtilities2;

import javax.swing.plaf.basic.DragRecognitionSupport.BeforeDrag;


Basis of a text components look-and-feel.  This provides the
basic editor view and controller services that may be useful
when creating a look-and-feel for an extension of
JTextComponent.

Most state is held in the associated JTextComponent
as bound properties, and the UI installs default values for the
various properties.  This default will install something for
all of the properties.  Typically, a LAF implementation will
do more however.  At a minimum, a LAF would generally install
key bindings.

This class also provides some concurrency support if the
Document associated with the JTextComponent is a subclass of
AbstractDocument.  Access to the View (or View hierarchy) is
serialized between any thread mutating the model and the Swing
event thread (which is expected to render, do model/view coordinate
translation, etc).  Any access to the root view should first
acquire a read-lock on the AbstractDocument and release that lock
in a finally block.
 An important method to define is the getPropertyPrefix method which is used as the basis of the keys used to fetch defaults from the UIManager. The string should reflect the type of TextUI (eg. TextField, TextArea, etc) without the particular LAF part of the name (eg Metal, Motif, etc). 

To build a view of the model, one of the following strategies
can be employed.

 One strategy is to simply redefine the ViewFactory interface in the UI. By default, this UI itself acts as the factory for View implementations. This is useful for simple factories. To do this reimplement the create method. 

A common strategy for creating more complex types of documents
is to have the EditorKit implementation return a factory.  Since
the EditorKit ties all of the pieces necessary to maintain a type
of document, the factory is typically an important part of that
and should be produced by the EditorKit implementation.


Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeans
has been added to the java.beans package. Please see XMLEncoder. 
Author:
Timothy Prinzing, Shannon Hickey (drag and drop)/**
 * <p>
 * Basis of a text components look-and-feel.  This provides the
 * basic editor view and controller services that may be useful
 * when creating a look-and-feel for an extension of
 * <code>JTextComponent</code>.
 * <p>
 * Most state is held in the associated <code>JTextComponent</code>
 * as bound properties, and the UI installs default values for the
 * various properties.  This default will install something for
 * all of the properties.  Typically, a LAF implementation will
 * do more however.  At a minimum, a LAF would generally install
 * key bindings.
 * <p>
 * This class also provides some concurrency support if the
 * <code>Document</code> associated with the JTextComponent is a subclass of
 * <code>AbstractDocument</code>.  Access to the View (or View hierarchy) is
 * serialized between any thread mutating the model and the Swing
 * event thread (which is expected to render, do model/view coordinate
 * translation, etc).  <em>Any access to the root view should first
 * acquire a read-lock on the AbstractDocument and release that lock
 * in a finally block.</em>
 * <p>
 * An important method to define is the {@link #getPropertyPrefix} method
 * which is used as the basis of the keys used to fetch defaults
 * from the UIManager.  The string should reflect the type of
 * TextUI (eg. TextField, TextArea, etc) without the particular
 * LAF part of the name (eg Metal, Motif, etc).
 * <p>
 * To build a view of the model, one of the following strategies
 * can be employed.
 * <ol>
 * <li>
 * One strategy is to simply redefine the
 * ViewFactory interface in the UI.  By default, this UI itself acts
 * as the factory for View implementations.  This is useful
 * for simple factories.  To do this reimplement the
 * {@link #create} method.
 * <li>
 * A common strategy for creating more complex types of documents
 * is to have the EditorKit implementation return a factory.  Since
 * the EditorKit ties all of the pieces necessary to maintain a type
 * of document, the factory is typically an important part of that
 * and should be produced by the EditorKit implementation.
 * </ol>
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Timothy Prinzing
 * @author Shannon Hickey (drag and drop)
 */
@SuppressWarnings("serial") // Same-version serialization only
public abstract class BasicTextUI extends TextUI implements ViewFactory {
    private static final int DEFAULT_CARET_MARGIN = 1;

    
Creates a new UI.
/**
     * Creates a new UI.
     */
    public BasicTextUI() {
        painted = false;
    }

    
Creates the object to use for a caret.  By default an
instance of BasicCaret is created.  This method
can be redefined to provide something else that implements
the InputPosition interface or a subclass of JCaret.
Returns:
the caret object/**
     * Creates the object to use for a caret.  By default an
     * instance of BasicCaret is created.  This method
     * can be redefined to provide something else that implements
     * the InputPosition interface or a subclass of JCaret.
     *
     * @return the caret object
     */
    protected Caret createCaret() {
        return new BasicCaret();
    }

    
Creates the object to use for adding highlights.  By default
an instance of BasicHighlighter is created.  This method
can be redefined to provide something else that implements
the Highlighter interface or a subclass of DefaultHighlighter.
Returns:
the highlighter/**
     * Creates the object to use for adding highlights.  By default
     * an instance of BasicHighlighter is created.  This method
     * can be redefined to provide something else that implements
     * the Highlighter interface or a subclass of DefaultHighlighter.
     *
     * @return the highlighter
     */
    protected Highlighter createHighlighter() {
        return new BasicHighlighter();
    }

    
Fetches the name of the keymap that will be installed/used
by default for this UI. This is implemented to create a
name based upon the classname.  The name is the name
of the class with the package prefix removed.
Returns:
the name/**
     * Fetches the name of the keymap that will be installed/used
     * by default for this UI. This is implemented to create a
     * name based upon the classname.  The name is the name
     * of the class with the package prefix removed.
     *
     * @return the name
     */
    protected String getKeymapName() {
        String nm = getClass().getName();
        int index = nm.lastIndexOf('.');
        if (index >= 0) {
            nm = nm.substring(index+1, nm.length());
        }
        return nm;
    }

    
Creates the keymap to use for the text component, and installs
any necessary bindings into it.  By default, the keymap is
shared between all instances of this type of TextUI. The
keymap has the name defined by the getKeymapName method.  If the
keymap is not found, then DEFAULT_KEYMAP from JTextComponent is used.
 The set of bindings used to create the keymap is fetched from the UIManager using a key formed by combining the getPropertyPrefix method and the string .keyBindings.  The type is expected
to be JTextComponent.KeyBinding[].
See Also:
getKeymapName
JTextComponent
Returns:
the keymap/**
     * Creates the keymap to use for the text component, and installs
     * any necessary bindings into it.  By default, the keymap is
     * shared between all instances of this type of TextUI. The
     * keymap has the name defined by the getKeymapName method.  If the
     * keymap is not found, then DEFAULT_KEYMAP from JTextComponent is used.
     * <p>
     * The set of bindings used to create the keymap is fetched
     * from the UIManager using a key formed by combining the
     * {@link #getPropertyPrefix} method
     * and the string <code>.keyBindings</code>.  The type is expected
     * to be <code>JTextComponent.KeyBinding[]</code>.
     *
     * @return the keymap
     * @see #getKeymapName
     * @see javax.swing.text.JTextComponent
     */
    protected Keymap createKeymap() {
        String nm = getKeymapName();
        Keymap map = JTextComponent.getKeymap(nm);
        if (map == null) {
            Keymap parent = JTextComponent.getKeymap(JTextComponent.DEFAULT_KEYMAP);
            map = JTextComponent.addKeymap(nm, parent);
            String prefix = getPropertyPrefix();
            Object o = DefaultLookup.get(editor, this,
                prefix + ".keyBindings");
            if ((o != null) && (o instanceof JTextComponent.KeyBinding[])) {
                JTextComponent.KeyBinding[] bindings = (JTextComponent.KeyBinding[]) o;
                JTextComponent.loadKeymap(map, bindings, getComponent().getActions());
            }
        }
        return map;
    }

    
This method gets called when a bound property is changed
on the associated JTextComponent.  This is a hook
which UI implementations may change to reflect how the
UI displays bound properties of JTextComponent subclasses.
This is implemented to do nothing (i.e. the response to
properties in JTextComponent itself are handled prior
to calling this method).
This implementation updates the background of the text
component if the editable and/or enabled state changes.
Params:
evt – the property change event/**
     * This method gets called when a bound property is changed
     * on the associated JTextComponent.  This is a hook
     * which UI implementations may change to reflect how the
     * UI displays bound properties of JTextComponent subclasses.
     * This is implemented to do nothing (i.e. the response to
     * properties in JTextComponent itself are handled prior
     * to calling this method).
     *
     * This implementation updates the background of the text
     * component if the editable and/or enabled state changes.
     *
     * @param evt the property change event
     */
    protected void propertyChange(PropertyChangeEvent evt) {
        if (evt.getPropertyName().equals("editable") ||
                evt.getPropertyName().equals("enabled")) {

            updateBackground((JTextComponent)evt.getSource());
        } else if (evt.getPropertyName().equals("caretWidth")) {
            Object value = evt.getNewValue();
            if (value instanceof Number) {
                int width = ((Number) value).intValue();
                if (width >= 0) caretMargin = width;
            }
        }
    }

    
Updates the background of the text component based on whether the
text component is editable and/or enabled.
Params:
c – the JTextComponent that needs its background color updated/**
     * Updates the background of the text component based on whether the
     * text component is editable and/or enabled.
     *
     * @param c the JTextComponent that needs its background color updated
     */
    private void updateBackground(JTextComponent c) {
        // This is a temporary workaround.
        // This code does not correctly deal with Synth (Synth doesn't use
        // properties like this), nor does it deal with the situation where
        // the developer grabs the color from a JLabel and sets it as
        // the background for a JTextArea in all look and feels. The problem
        // scenario results if the Color obtained for the Label and TextArea
        // is ==, which is the case for the windows look and feel.
        // Until an appropriate solution is found, the code is being
        // reverted to what it was before the original fix.
        if (this instanceof SynthUI || (c instanceof JTextArea)) {
            return;
        }
        Color background = c.getBackground();
        if (background instanceof UIResource) {
            String prefix = getPropertyPrefix();

            Color disabledBG =
                DefaultLookup.getColor(c, this, prefix + ".disabledBackground", null);
            Color inactiveBG =
                DefaultLookup.getColor(c, this, prefix + ".inactiveBackground", null);
            Color bg =
                DefaultLookup.getColor(c, this, prefix + ".background", null);

            /* In an ideal situation, the following check would not be necessary
             * and we would replace the color any time the previous color was a
             * UIResouce. However, it turns out that there is existing code that
             * uses the following inadvisable pattern to turn a text area into
             * what appears to be a multi-line label:
             *
             * JLabel label = new JLabel();
             * JTextArea area = new JTextArea();
             * area.setBackground(label.getBackground());
             * area.setEditable(false);
             *
             * JLabel's default background is a UIResource. As such, just
             * checking for UIResource would have us always changing the
             * background away from what the developer wanted.
             *
             * Therefore, for JTextArea/JEditorPane, we'll additionally check
             * that the color we're about to replace matches one that was
             * installed by us from the UIDefaults.
             */
            if ((c instanceof JTextArea || c instanceof JEditorPane)
                    && background != disabledBG
                    && background != inactiveBG
                    && background != bg) {

                return;
            }

            Color newColor = null;
            if (!c.isEnabled()) {
                newColor = disabledBG;
            }
            if (newColor == null && !c.isEditable()) {
                newColor = inactiveBG;
            }
            if (newColor == null) {
                newColor = bg;
            }
            if (newColor != null && newColor != background) {
                c.setBackground(newColor);
            }
        }
    }

    
Gets the name used as a key to look up properties through the
UIManager.  This is used as a prefix to all the standard
text properties.
Returns:
the name/**
     * Gets the name used as a key to look up properties through the
     * UIManager.  This is used as a prefix to all the standard
     * text properties.
     *
     * @return the name
     */
    protected abstract String getPropertyPrefix();

    
Initializes component properties, such as font, foreground,
background, caret color, selection color, selected text color,
disabled text color, and border color.  The font, foreground, and
background properties are only set if their current value is either null
or a UIResource, other properties are set if the current
value is null.
See Also:
uninstallDefaults
installUI/**
     * Initializes component properties, such as font, foreground,
     * background, caret color, selection color, selected text color,
     * disabled text color, and border color.  The font, foreground, and
     * background properties are only set if their current value is either null
     * or a UIResource, other properties are set if the current
     * value is null.
     *
     * @see #uninstallDefaults
     * @see #installUI
     */
    protected void installDefaults()
    {
        String prefix = getPropertyPrefix();
        Font f = editor.getFont();
        if ((f == null) || (f instanceof UIResource)) {
            editor.setFont(UIManager.getFont(prefix + ".font"));
        }

        Color bg = editor.getBackground();
        if ((bg == null) || (bg instanceof UIResource)) {
            editor.setBackground(UIManager.getColor(prefix + ".background"));
        }

        Color fg = editor.getForeground();
        if ((fg == null) || (fg instanceof UIResource)) {
            editor.setForeground(UIManager.getColor(prefix + ".foreground"));
        }

        Color color = editor.getCaretColor();
        if ((color == null) || (color instanceof UIResource)) {
            editor.setCaretColor(UIManager.getColor(prefix + ".caretForeground"));
        }

        Color s = editor.getSelectionColor();
        if ((s == null) || (s instanceof UIResource)) {
            editor.setSelectionColor(UIManager.getColor(prefix + ".selectionBackground"));
        }

        Color sfg = editor.getSelectedTextColor();
        if ((sfg == null) || (sfg instanceof UIResource)) {
            editor.setSelectedTextColor(UIManager.getColor(prefix + ".selectionForeground"));
        }

        Color dfg = editor.getDisabledTextColor();
        if ((dfg == null) || (dfg instanceof UIResource)) {
            editor.setDisabledTextColor(UIManager.getColor(prefix + ".inactiveForeground"));
        }

        Border b = editor.getBorder();
        if ((b == null) || (b instanceof UIResource)) {
            editor.setBorder(UIManager.getBorder(prefix + ".border"));
        }

        Insets margin = editor.getMargin();
        if (margin == null || margin instanceof UIResource) {
            editor.setMargin(UIManager.getInsets(prefix + ".margin"));
        }

        updateCursor();
    }

    private void installDefaults2() {
        editor.addMouseListener(dragListener);
        editor.addMouseMotionListener(dragListener);

        String prefix = getPropertyPrefix();

        Caret caret = editor.getCaret();
        if (caret == null || caret instanceof UIResource) {
            caret = createCaret();
            editor.setCaret(caret);

            int rate = DefaultLookup.getInt(getComponent(), this, prefix + ".caretBlinkRate", 500);
            caret.setBlinkRate(rate);
        }

        Highlighter highlighter = editor.getHighlighter();
        if (highlighter == null || highlighter instanceof UIResource) {
            editor.setHighlighter(createHighlighter());
        }

        TransferHandler th = editor.getTransferHandler();
        if (th == null || th instanceof UIResource) {
            editor.setTransferHandler(getTransferHandler());
        }
    }

    
Sets the component properties that have not been explicitly overridden to null. A property is considered overridden if its current value is not a UIResource. 
See Also:
installDefaults
uninstallUI/**
     * Sets the component properties that have not been explicitly overridden
     * to {@code null}.  A property is considered overridden if its current
     * value is not a {@code UIResource}.
     *
     * @see #installDefaults
     * @see #uninstallUI
     */
    protected void uninstallDefaults()
    {
        editor.removeMouseListener(dragListener);
        editor.removeMouseMotionListener(dragListener);

        if (editor.getCaretColor() instanceof UIResource) {
            editor.setCaretColor(null);
        }

        if (editor.getSelectionColor() instanceof UIResource) {
            editor.setSelectionColor(null);
        }

        if (editor.getDisabledTextColor() instanceof UIResource) {
            editor.setDisabledTextColor(null);
        }

        if (editor.getSelectedTextColor() instanceof UIResource) {
            editor.setSelectedTextColor(null);
        }

        if (editor.getBorder() instanceof UIResource) {
            editor.setBorder(null);
        }

        if (editor.getMargin() instanceof UIResource) {
            editor.setMargin(null);
        }

        if (editor.getCaret() instanceof UIResource) {
            editor.setCaret(null);
        }

        if (editor.getHighlighter() instanceof UIResource) {
            editor.setHighlighter(null);
        }

        if (editor.getTransferHandler() instanceof UIResource) {
            editor.setTransferHandler(null);
        }

        if (editor.getCursor() instanceof UIResource) {
            editor.setCursor(null);
        }
    }

    
Installs listeners for the UI.
/**
     * Installs listeners for the UI.
     */
    protected void installListeners() {
    }

    
Uninstalls listeners for the UI.
/**
     * Uninstalls listeners for the UI.
     */
    protected void uninstallListeners() {
    }

    
Registers keyboard actions.
/**
     * Registers keyboard actions.
     */
    protected void installKeyboardActions() {
        // backward compatibility support... keymaps for the UI
        // are now installed in the more friendly input map.
        editor.setKeymap(createKeymap());

        InputMap km = getInputMap();
        if (km != null) {
            SwingUtilities.replaceUIInputMap(editor, JComponent.WHEN_FOCUSED,
                                             km);
        }

        ActionMap map = getActionMap();
        if (map != null) {
            SwingUtilities.replaceUIActionMap(editor, map);
        }

        updateFocusAcceleratorBinding(false);
    }

    
Get the InputMap to use for the UI.
/**
     * Get the InputMap to use for the UI.
     */
    InputMap getInputMap() {
        InputMap map = new InputMapUIResource();

        InputMap shared =
            (InputMap)DefaultLookup.get(editor, this,
            getPropertyPrefix() + ".focusInputMap");
        if (shared != null) {
            map.setParent(shared);
        }
        return map;
    }

    
Invoked when the focus accelerator changes, this will update the
key bindings as necessary.
/**
     * Invoked when the focus accelerator changes, this will update the
     * key bindings as necessary.
     */
    void updateFocusAcceleratorBinding(boolean changed) {
        char accelerator = editor.getFocusAccelerator();

        if (changed || accelerator != '\0') {
            InputMap km = SwingUtilities.getUIInputMap
                        (editor, JComponent.WHEN_IN_FOCUSED_WINDOW);

            if (km == null && accelerator != '\0') {
                km = new ComponentInputMapUIResource(editor);
                SwingUtilities.replaceUIInputMap(editor, JComponent.
                                                 WHEN_IN_FOCUSED_WINDOW, km);
                ActionMap am = getActionMap();
                SwingUtilities.replaceUIActionMap(editor, am);
            }
            if (km != null) {
                km.clear();
                if (accelerator != '\0') {
                    km.put(KeyStroke.getKeyStroke(accelerator, BasicLookAndFeel.getFocusAcceleratorKeyMask()), "requestFocus");
                    km.put(KeyStroke.getKeyStroke(accelerator,
                            SwingUtilities2.setAltGraphMask(
                            BasicLookAndFeel.getFocusAcceleratorKeyMask())),
                            "requestFocus");
                }
            }
        }
    }


    
Invoked when editable property is changed.
removing 'TAB' and 'SHIFT-TAB' from traversalKeysSet in case
editor is editable
adding 'TAB' and 'SHIFT-TAB' to traversalKeysSet in case
editor is non editable
/**
     * Invoked when editable property is changed.
     *
     * removing 'TAB' and 'SHIFT-TAB' from traversalKeysSet in case
     * editor is editable
     * adding 'TAB' and 'SHIFT-TAB' to traversalKeysSet in case
     * editor is non editable
     */
    @SuppressWarnings("deprecation")
    void updateFocusTraversalKeys() {
        /*
         * Fix for 4514331 Non-editable JTextArea and similar
         * should allow Tab to keyboard - accessibility
         */
        EditorKit editorKit = getEditorKit(editor);
        if ( editorKit != null
             && editorKit instanceof DefaultEditorKit) {
            Set<AWTKeyStroke> storedForwardTraversalKeys = editor.
                getFocusTraversalKeys(KeyboardFocusManager.
                                      FORWARD_TRAVERSAL_KEYS);
            Set<AWTKeyStroke> storedBackwardTraversalKeys = editor.
                getFocusTraversalKeys(KeyboardFocusManager.
                                      BACKWARD_TRAVERSAL_KEYS);
            Set<AWTKeyStroke> forwardTraversalKeys =
                new HashSet<AWTKeyStroke>(storedForwardTraversalKeys);
            Set<AWTKeyStroke> backwardTraversalKeys =
                new HashSet<AWTKeyStroke>(storedBackwardTraversalKeys);
            if (editor.isEditable()) {
                forwardTraversalKeys.
                    remove(KeyStroke.getKeyStroke(KeyEvent.VK_TAB, 0));
                backwardTraversalKeys.
                    remove(KeyStroke.getKeyStroke(KeyEvent.VK_TAB,
                                                  InputEvent.SHIFT_MASK));
            } else {
                forwardTraversalKeys.add(KeyStroke.
                                         getKeyStroke(KeyEvent.VK_TAB, 0));
                backwardTraversalKeys.
                    add(KeyStroke.
                        getKeyStroke(KeyEvent.VK_TAB, InputEvent.SHIFT_MASK));
            }
            LookAndFeel.installProperty(editor,
                                        "focusTraversalKeysForward",
                                         forwardTraversalKeys);
            LookAndFeel.installProperty(editor,
                                        "focusTraversalKeysBackward",
                                         backwardTraversalKeys);
        }

    }

    
As needed updates cursor for the target editor.
/**
     * As needed updates cursor for the target editor.
     */
    private void updateCursor() {
        if ((! editor.isCursorSet())
               || editor.getCursor() instanceof UIResource) {
            Cursor cursor = (editor.isEditable()) ? textCursor : null;
            editor.setCursor(cursor);
        }
    }

    
Returns the TransferHandler that will be installed if
their isn't one installed on the JTextComponent.
/**
     * Returns the <code>TransferHandler</code> that will be installed if
     * their isn't one installed on the <code>JTextComponent</code>.
     */
    TransferHandler getTransferHandler() {
        return defaultTransferHandler;
    }

    
Fetch an action map to use.
/**
     * Fetch an action map to use.
     */
    ActionMap getActionMap() {
        String mapName = getPropertyPrefix() + ".actionMap";
        ActionMap map = (ActionMap)UIManager.get(mapName);

        if (map == null) {
            map = createActionMap();
            if (map != null) {
                UIManager.getLookAndFeelDefaults().put(mapName, map);
            }
        }
        ActionMap componentMap = new ActionMapUIResource();
        componentMap.put("requestFocus", new FocusAction());
        /*
         * fix for bug 4515750
         * JTextField & non-editable JTextArea bind return key - default btn not accessible
         *
         * Wrap the return action so that it is only enabled when the
         * component is editable. This allows the default button to be
         * processed when the text component has focus and isn't editable.
         *
         */
        if (getEditorKit(editor) instanceof DefaultEditorKit) {
            if (map != null) {
                Object obj = map.get(DefaultEditorKit.insertBreakAction);
                if (obj != null
                    && obj instanceof DefaultEditorKit.InsertBreakAction) {
                    Action action =  new TextActionWrapper((TextAction)obj);
                    componentMap.put(action.getValue(Action.NAME),action);
                }
            }
        }
        if (map != null) {
            componentMap.setParent(map);
        }
        return componentMap;
    }

    
Create a default action map.  This is basically the
set of actions found exported by the component.
/**
     * Create a default action map.  This is basically the
     * set of actions found exported by the component.
     */
    ActionMap createActionMap() {
        ActionMap map = new ActionMapUIResource();
        Action[] actions = editor.getActions();
        //System.out.println("building map for UI: " + getPropertyPrefix());
        int n = actions.length;
        for (int i = 0; i < n; i++) {
            Action a = actions[i];
            map.put(a.getValue(Action.NAME), a);
            //System.out.println("  " + a.getValue(Action.NAME));
        }
        map.put(TransferHandler.getCutAction().getValue(Action.NAME),
                TransferHandler.getCutAction());
        map.put(TransferHandler.getCopyAction().getValue(Action.NAME),
                TransferHandler.getCopyAction());
        map.put(TransferHandler.getPasteAction().getValue(Action.NAME),
                TransferHandler.getPasteAction());
        return map;
    }

    
Unregisters keyboard actions.
/**
     * Unregisters keyboard actions.
     */
    protected void uninstallKeyboardActions() {
        editor.setKeymap(null);
        SwingUtilities.replaceUIInputMap(editor, JComponent.
                                         WHEN_IN_FOCUSED_WINDOW, null);
        SwingUtilities.replaceUIActionMap(editor, null);
    }

    
Paints a background for the view.  This will only be
called if isOpaque() on the associated component is
true.  The default is to paint the background color
of the component.
Params:
g – the graphics context/**
     * Paints a background for the view.  This will only be
     * called if isOpaque() on the associated component is
     * true.  The default is to paint the background color
     * of the component.
     *
     * @param g the graphics context
     */
    protected void paintBackground(Graphics g) {
        g.setColor(editor.getBackground());
        g.fillRect(0, 0, editor.getWidth(), editor.getHeight());
    }

    
Fetches the text component associated with this
UI implementation.  This will be null until
the ui has been installed.
Returns:
the editor component/**
     * Fetches the text component associated with this
     * UI implementation.  This will be null until
     * the ui has been installed.
     *
     * @return the editor component
     */
    protected final JTextComponent getComponent() {
        return editor;
    }

    
Flags model changes.
This is called whenever the model has changed.
It is implemented to rebuild the view hierarchy
to represent the default root element of the
associated model.
/**
     * Flags model changes.
     * This is called whenever the model has changed.
     * It is implemented to rebuild the view hierarchy
     * to represent the default root element of the
     * associated model.
     */
    protected void modelChanged() {
        // create a view hierarchy
        ViewFactory f = rootView.getViewFactory();
        Document doc = editor.getDocument();
        Element elem = doc.getDefaultRootElement();
        setView(f.create(elem));
    }

    
Sets the current root of the view hierarchy and calls invalidate().
If there were any child components, they will be removed (i.e.
there are assumed to have come from components embedded in views).
Params:
v – the root view/**
     * Sets the current root of the view hierarchy and calls invalidate().
     * If there were any child components, they will be removed (i.e.
     * there are assumed to have come from components embedded in views).
     *
     * @param v the root view
     */
    protected final void setView(View v) {
        rootView.setView(v);
        painted = false;
        editor.revalidate();
        editor.repaint();
    }

    
Paints the interface safely with a guarantee that
the model won't change from the view of this thread.
This does the following things, rendering from
back to front.


If the component is marked as opaque, the background
is painted in the current background color of the
component.

The highlights (if any) are painted.

The view hierarchy is painted.

The caret is painted.

Params:
g – the graphics context/**
     * Paints the interface safely with a guarantee that
     * the model won't change from the view of this thread.
     * This does the following things, rendering from
     * back to front.
     * <ol>
     * <li>
     * If the component is marked as opaque, the background
     * is painted in the current background color of the
     * component.
     * <li>
     * The highlights (if any) are painted.
     * <li>
     * The view hierarchy is painted.
     * <li>
     * The caret is painted.
     * </ol>
     *
     * @param g the graphics context
     */
    protected void paintSafely(Graphics g) {
        painted = true;
        Highlighter highlighter = editor.getHighlighter();
        Caret caret = editor.getCaret();

        // paint the background
        if (editor.isOpaque()) {
            paintBackground(g);
        }

        // paint the highlights
        if (highlighter != null) {
            highlighter.paint(g);
        }

        // paint the view hierarchy
        Rectangle alloc = getVisibleEditorRect();
        if (alloc != null) {
            rootView.paint(g, alloc);
        }

        // paint the caret
        if (caret != null) {
            caret.paint(g);
        }

        if (dropCaret != null) {
            dropCaret.paint(g);
        }
    }

    // --- ComponentUI methods --------------------------------------------

    
Installs the UI for a component.  This does the following
things.


Sets the associated component to opaque if the opaque property
has not already been set by the client program. This will cause the
component's background color to be painted.
 Installs the default caret and highlighter into the associated component. These properties are only set if their current value is either null or an instance of UIResource. 

Attaches to the editor and model.  If there is no
model, a default one is created.

Creates the view factory and the view hierarchy used
to represent the model.

Params:
c – the editor component
See Also:
ComponentUI.installUI/**
     * Installs the UI for a component.  This does the following
     * things.
     * <ol>
     * <li>
     * Sets the associated component to opaque if the opaque property
     * has not already been set by the client program. This will cause the
     * component's background color to be painted.
     * <li>
     * Installs the default caret and highlighter into the
     * associated component. These properties are only set if their
     * current value is either {@code null} or an instance of
     * {@link UIResource}.
     * <li>
     * Attaches to the editor and model.  If there is no
     * model, a default one is created.
     * <li>
     * Creates the view factory and the view hierarchy used
     * to represent the model.
     * </ol>
     *
     * @param c the editor component
     * @see ComponentUI#installUI
     */
    public void installUI(JComponent c) {
        if (c instanceof JTextComponent) {
            editor = (JTextComponent) c;

            // common case is background painted... this can
            // easily be changed by subclasses or from outside
            // of the component.
            LookAndFeel.installProperty(editor, "opaque", Boolean.TRUE);
            LookAndFeel.installProperty(editor, "autoscrolls", Boolean.TRUE);

            // install defaults
            installDefaults();
            installDefaults2();

            // margin required to show caret in the rightmost position
            caretMargin = -1;
            Object property = UIManager.get("Caret.width");
            if (property instanceof Number) {
                caretMargin = ((Number) property).intValue();
            }
            property = c.getClientProperty("caretWidth");
            if (property instanceof Number) {
                caretMargin = ((Number) property).intValue();
            }
            if (caretMargin < 0) {
                caretMargin = DEFAULT_CARET_MARGIN;
            }

            // attach to the model and editor
            editor.addPropertyChangeListener(updateHandler);
            Document doc = editor.getDocument();
            if (doc == null) {
                // no model, create a default one.  This will
                // fire a notification to the updateHandler
                // which takes care of the rest.
                editor.setDocument(getEditorKit(editor).createDefaultDocument());
            } else {
                doc.addDocumentListener(updateHandler);
                modelChanged();
            }

            // install keymap
            installListeners();
            installKeyboardActions();

            LayoutManager oldLayout = editor.getLayout();
            if ((oldLayout == null) || (oldLayout instanceof UIResource)) {
                // by default, use default LayoutManger implementation that
                // will position the components associated with a View object.
                editor.setLayout(updateHandler);
            }

            updateBackground(editor);
        } else {
            throw new Error("TextUI needs JTextComponent");
        }
    }

    
Deinstalls the UI for a component.  This removes the listeners,
uninstalls the highlighter, removes views, and nulls out the keymap.
Params:
c – the editor component
See Also:
ComponentUI.uninstallUI/**
     * Deinstalls the UI for a component.  This removes the listeners,
     * uninstalls the highlighter, removes views, and nulls out the keymap.
     *
     * @param c the editor component
     * @see ComponentUI#uninstallUI
     */
    public void uninstallUI(JComponent c) {
        // detach from the model
        editor.removePropertyChangeListener(updateHandler);
        editor.getDocument().removeDocumentListener(updateHandler);

        // view part
        painted = false;
        uninstallDefaults();
        rootView.setView(null);
        c.removeAll();
        LayoutManager lm = c.getLayout();
        if (lm instanceof UIResource) {
            c.setLayout(null);
        }

        // controller part
        uninstallKeyboardActions();
        uninstallListeners();

        editor = null;
    }

    
Superclass paints background in an uncontrollable way
(i.e. one might want an image tiled into the background).
To prevent this from happening twice, this method is
reimplemented to simply paint.

NOTE: Superclass is also not thread-safe in its
rendering of the background, although that is not an issue with the
default rendering.
/**
     * Superclass paints background in an uncontrollable way
     * (i.e. one might want an image tiled into the background).
     * To prevent this from happening twice, this method is
     * reimplemented to simply paint.
     * <p>
     * <em>NOTE:</em> Superclass is also not thread-safe in its
     * rendering of the background, although that is not an issue with the
     * default rendering.
     */
    public void update(Graphics g, JComponent c) {
        paint(g, c);
    }

    
Paints the interface.  This is routed to the
paintSafely method under the guarantee that
the model won't change from the view of this thread
while it's rendering (if the associated model is
derived from AbstractDocument).  This enables the
model to potentially be updated asynchronously.
Params:
g – the graphics context
c – the editor component/**
     * Paints the interface.  This is routed to the
     * paintSafely method under the guarantee that
     * the model won't change from the view of this thread
     * while it's rendering (if the associated model is
     * derived from AbstractDocument).  This enables the
     * model to potentially be updated asynchronously.
     *
     * @param g the graphics context
     * @param c the editor component
     */
    public final void paint(Graphics g, JComponent c) {
        if ((rootView.getViewCount() > 0) && (rootView.getView(0) != null)) {
            Document doc = editor.getDocument();
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readLock();
            }
            try {
                paintSafely(g);
            } finally {
                if (doc instanceof AbstractDocument) {
                    ((AbstractDocument)doc).readUnlock();
                }
            }
        }
    }

    
Gets the preferred size for the editor component.  If the component
has been given a size prior to receiving this request, it will
set the size of the view hierarchy to reflect the size of the component
before requesting the preferred size of the view hierarchy.  This
allows formatted views to format to the current component size before
answering the request.  Other views don't care about currently formatted
size and give the same answer either way.
Params:
c – the editor component
Returns:
the size/**
     * Gets the preferred size for the editor component.  If the component
     * has been given a size prior to receiving this request, it will
     * set the size of the view hierarchy to reflect the size of the component
     * before requesting the preferred size of the view hierarchy.  This
     * allows formatted views to format to the current component size before
     * answering the request.  Other views don't care about currently formatted
     * size and give the same answer either way.
     *
     * @param c the editor component
     * @return the size
     */
    public Dimension getPreferredSize(JComponent c) {
        Document doc = editor.getDocument();
        Insets i = c.getInsets();
        Dimension d = c.getSize();

        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).readLock();
        }
        try {
            if ((d.width > (i.left + i.right + caretMargin)) && (d.height > (i.top + i.bottom))) {
                rootView.setSize(d.width - i.left - i.right -
                        caretMargin, d.height - i.top - i.bottom);
            } else if (d.width == 0 && d.height == 0) {
                // Probably haven't been layed out yet, force some sort of
                // initial sizing.
                rootView.setSize(Integer.MAX_VALUE, Integer.MAX_VALUE);
            }
            d.width = (int) Math.min((long) rootView.getPreferredSpan(View.X_AXIS) +
                         (long) i.left + (long) i.right + caretMargin, Integer.MAX_VALUE);
            d.height = (int) Math.min((long) rootView.getPreferredSpan(View.Y_AXIS) +
                                      (long) i.top + (long) i.bottom, Integer.MAX_VALUE);
        } finally {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readUnlock();
            }
        }
        return d;
    }

    
Gets the minimum size for the editor component.
Params:
c – the editor component
Returns:
the size/**
     * Gets the minimum size for the editor component.
     *
     * @param c the editor component
     * @return the size
     */
    public Dimension getMinimumSize(JComponent c) {
        Document doc = editor.getDocument();
        Insets i = c.getInsets();
        Dimension d = new Dimension();
        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).readLock();
        }
        try {
            d.width = (int) rootView.getMinimumSpan(View.X_AXIS) + i.left + i.right + caretMargin;
            d.height = (int)  rootView.getMinimumSpan(View.Y_AXIS) + i.top + i.bottom;
        } finally {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readUnlock();
            }
        }
        return d;
    }

    
Gets the maximum size for the editor component.
Params:
c – the editor component
Returns:
the size/**
     * Gets the maximum size for the editor component.
     *
     * @param c the editor component
     * @return the size
     */
    public Dimension getMaximumSize(JComponent c) {
        Document doc = editor.getDocument();
        Insets i = c.getInsets();
        Dimension d = new Dimension();
        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).readLock();
        }
        try {
            d.width = (int) Math.min((long) rootView.getMaximumSpan(View.X_AXIS) +
                                     (long) i.left + (long) i.right + caretMargin, Integer.MAX_VALUE);
            d.height = (int) Math.min((long) rootView.getMaximumSpan(View.Y_AXIS) +
                                      (long) i.top + (long) i.bottom, Integer.MAX_VALUE);
        } finally {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readUnlock();
            }
        }
        return d;
    }

    // ---- TextUI methods -------------------------------------------


    
Gets the allocation to give the root View.  Due
to an unfortunate set of historical events this
method is inappropriately named.  The Rectangle
returned has nothing to do with visibility.
The component must have a non-zero positive size for
this translation to be computed.
Returns:
the bounding box for the root view/**
     * Gets the allocation to give the root View.  Due
     * to an unfortunate set of historical events this
     * method is inappropriately named.  The Rectangle
     * returned has nothing to do with visibility.
     * The component must have a non-zero positive size for
     * this translation to be computed.
     *
     * @return the bounding box for the root view
     */
    protected Rectangle getVisibleEditorRect() {
        Rectangle alloc = editor.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 + caretMargin;
            alloc.height -= insets.top + insets.bottom;
            return alloc;
        }
        return null;
    }

    
Converts the given location in the model to a place in
the view coordinate system.
The component must have a non-zero positive size for
this translation to be computed.
Params:
tc – the text component for which this UI is installed
pos – the local location in the model to translate >= 0
Throws:
BadLocationException –  if the given position does not
  represent a valid location in the associated document
See Also:
TextUI.modelToView
Returns:
the coordinates as a rectangle, null if the model is not painted
Deprecated:
replaced by modelToView2D(JTextComponent, int, Bias)/**
     * Converts the given location in the model to a place in
     * the view coordinate system.
     * The component must have a non-zero positive size for
     * this translation to be computed.
     *
     * @param tc the text component for which this UI is installed
     * @param pos the local location in the model to translate &gt;= 0
     * @return the coordinates as a rectangle, null if the model is not painted
     * @exception BadLocationException  if the given position does not
     *   represent a valid location in the associated document
     * @see TextUI#modelToView
     *
     * @deprecated replaced by
     *     {@link #modelToView2D(JTextComponent, int, Position.Bias)}
     */
    @Deprecated(since = "9")
    @Override
    public Rectangle modelToView(JTextComponent tc, int pos) throws BadLocationException {
        return modelToView(tc, pos, Position.Bias.Forward);
    }

    
Converts the given location in the model to a place in
the view coordinate system.
The component must have a non-zero positive size for
this translation to be computed.
Params:
tc – the text component for which this UI is installed
pos – the local location in the model to translate >= 0
Throws:
BadLocationException –  if the given position does not
  represent a valid location in the associated document
See Also:
TextUI.modelToView
Returns:
the coordinates as a rectangle, null if the model is not painted
Deprecated:
replaced by modelToView2D(JTextComponent, int, Bias)/**
     * Converts the given location in the model to a place in
     * the view coordinate system.
     * The component must have a non-zero positive size for
     * this translation to be computed.
     *
     * @param tc the text component for which this UI is installed
     * @param pos the local location in the model to translate &gt;= 0
     * @return the coordinates as a rectangle, null if the model is not painted
     * @exception BadLocationException  if the given position does not
     *   represent a valid location in the associated document
     * @see TextUI#modelToView
     *
     * @deprecated replaced by
     *     {@link #modelToView2D(JTextComponent, int, Position.Bias)}
     */
    @Deprecated(since = "9")
    @Override
    public Rectangle modelToView(JTextComponent tc, int pos, Position.Bias bias)
            throws BadLocationException
    {
        return (Rectangle) modelToView(tc, pos, bias, false);
    }

    @Override
    public Rectangle2D modelToView2D(JTextComponent tc, int pos,
                                     Position.Bias bias)
            throws BadLocationException
    {
        return modelToView(tc, pos, bias, true);
    }

    private Rectangle2D modelToView(JTextComponent tc, int pos,
                                    Position.Bias bias, boolean useFPAPI)
            throws BadLocationException
    {
        Document doc = editor.getDocument();
        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).readLock();
        }
        try {
            Rectangle alloc = getVisibleEditorRect();
            if (alloc != null) {
                rootView.setSize(alloc.width, alloc.height);
                Shape s = rootView.modelToView(pos, alloc, bias);
                if (s != null) {
                    return useFPAPI ? s.getBounds2D() : s.getBounds();
                }
            }
        } finally {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readUnlock();
            }
        }
        return null;
    }

    
Converts the given place in the view coordinate system
to the nearest representative location in the model.
The component must have a non-zero positive size for
this translation to be computed.
Params:
tc – the text component for which this UI is installed
pt – the location in the view to translate.  This
 should be in the same coordinate system as the mouse events.
See Also:
TextUI.viewToModel
Returns:
the offset from the start of the document >= 0,
  -1 if not painted
Deprecated:
replaced by viewToModel2D(JTextComponent, Point2D, Bias[])/**
     * Converts the given place in the view coordinate system
     * to the nearest representative location in the model.
     * The component must have a non-zero positive size for
     * this translation to be computed.
     *
     * @param tc the text component for which this UI is installed
     * @param pt the location in the view to translate.  This
     *  should be in the same coordinate system as the mouse events.
     * @return the offset from the start of the document &gt;= 0,
     *   -1 if not painted
     * @see TextUI#viewToModel
     *
     * @deprecated replaced by
     *     {@link #viewToModel2D(JTextComponent, Point2D, Position.Bias[])}
     */
    @Deprecated(since = "9")
    @Override
    public int viewToModel(JTextComponent tc, Point pt) {
        return viewToModel(tc, pt, discardBias);
    }

    
Converts the given place in the view coordinate system
to the nearest representative location in the model.
The component must have a non-zero positive size for
this translation to be computed.
Params:
tc – the text component for which this UI is installed
pt – the location in the view to translate.  This
 should be in the same coordinate system as the mouse events.
See Also:
TextUI.viewToModel
Returns:
the offset from the start of the document >= 0,
  -1 if the component doesn't yet have a positive size.
Deprecated:
replaced by viewToModel2D(JTextComponent, Point2D, Bias[])/**
     * Converts the given place in the view coordinate system
     * to the nearest representative location in the model.
     * The component must have a non-zero positive size for
     * this translation to be computed.
     *
     * @param tc the text component for which this UI is installed
     * @param pt the location in the view to translate.  This
     *  should be in the same coordinate system as the mouse events.
     * @return the offset from the start of the document &gt;= 0,
     *   -1 if the component doesn't yet have a positive size.
     * @see TextUI#viewToModel
     *
     * @deprecated replaced by
     *     {@link #viewToModel2D(JTextComponent, Point2D, Position.Bias[])}
     */
    @Deprecated(since = "9")
    @Override
    public int viewToModel(JTextComponent tc, Point pt,
                           Position.Bias[] biasReturn) {
        return viewToModel(tc, pt.x, pt.y, biasReturn);
    }

    @Override
    public int viewToModel2D(JTextComponent tc, Point2D pt,
                             Position.Bias[] biasReturn) {
        return viewToModel(tc, (float) pt.getX(), (float) pt.getY(), biasReturn);
    }

    private int viewToModel(JTextComponent tc, float x, float y,
                            Position.Bias[] biasReturn) {
        int offs = -1;
        Document doc = editor.getDocument();
        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).readLock();
        }
        try {
            Rectangle alloc = getVisibleEditorRect();
            if (alloc != null) {
                rootView.setSize(alloc.width, alloc.height);
                offs = rootView.viewToModel(x, y, alloc, biasReturn);
            }
        } finally {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readUnlock();
            }
        }
        return offs;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public int getNextVisualPositionFrom(JTextComponent t, int pos,
                    Position.Bias b, int direction, Position.Bias[] biasRet)
                    throws BadLocationException{
        Document doc = editor.getDocument();

        if (pos < -1 || pos > doc.getLength()) {
            throw new BadLocationException("Invalid position", pos);
        }

        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).readLock();
        }
        try {
            if (painted) {
                Rectangle alloc = getVisibleEditorRect();
                if (alloc != null) {
                    rootView.setSize(alloc.width, alloc.height);
                }
                return rootView.getNextVisualPositionFrom(pos, b, alloc, direction,
                                                          biasRet);
            }
        } finally {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readUnlock();
            }
        }
        return -1;
    }

    
Causes the portion of the view responsible for the
given part of the model to be repainted.  Does nothing if
the view is not currently painted.
Params:
tc – the text component for which this UI is installed
p0 – the beginning of the range >= 0
p1 – the end of the range >= p0
See Also:
TextUI.damageRange/**
     * Causes the portion of the view responsible for the
     * given part of the model to be repainted.  Does nothing if
     * the view is not currently painted.
     *
     * @param tc the text component for which this UI is installed
     * @param p0 the beginning of the range &gt;= 0
     * @param p1 the end of the range &gt;= p0
     * @see TextUI#damageRange
     */
    public void damageRange(JTextComponent tc, int p0, int p1) {
        damageRange(tc, p0, p1, Position.Bias.Forward, Position.Bias.Backward);
    }

    
Causes the portion of the view responsible for the
given part of the model to be repainted.
Params:
p0 – the beginning of the range >= 0
p1 – the end of the range >= p0/**
     * Causes the portion of the view responsible for the
     * given part of the model to be repainted.
     *
     * @param p0 the beginning of the range &gt;= 0
     * @param p1 the end of the range &gt;= p0
     */
    public void damageRange(JTextComponent t, int p0, int p1,
                            Position.Bias p0Bias, Position.Bias p1Bias) {
        if (painted) {
            Rectangle alloc = getVisibleEditorRect();
            if (alloc != null) {
                Document doc = t.getDocument();
                if (doc instanceof AbstractDocument) {
                    ((AbstractDocument)doc).readLock();
                }
                try {
                    rootView.setSize(alloc.width, alloc.height);
                    Shape toDamage = rootView.modelToView(p0, p0Bias,
                            p1, p1Bias, alloc);
                    Rectangle rect = (toDamage instanceof Rectangle) ?
                            (Rectangle)toDamage : toDamage.getBounds();
                    editor.repaint(rect.x, rect.y, rect.width, rect.height);
                } catch (BadLocationException e) {
                } finally {
                    if (doc instanceof AbstractDocument) {
                        ((AbstractDocument)doc).readUnlock();
                    }
                }
            }
        }
    }

    
Fetches the EditorKit for the UI.
Params:
tc – the text component for which this UI is installed
See Also:
TextUI.getEditorKit
Returns:
the editor capabilities/**
     * Fetches the EditorKit for the UI.
     *
     * @param tc the text component for which this UI is installed
     * @return the editor capabilities
     * @see TextUI#getEditorKit
     */
    public EditorKit getEditorKit(JTextComponent tc) {
        return defaultKit;
    }

    
Fetches a View with the allocation of the associated
text component (i.e. the root of the hierarchy) that
can be traversed to determine how the model is being
represented spatially.

Warning: The View hierarchy can
be traversed from the root view, and other things
can be done as well.  Things done in this way cannot
be protected like simple method calls through the TextUI.
Therefore, proper operation in the presence of concurrency
must be arranged by any logic that calls this method!
Params:
tc – the text component for which this UI is installed
See Also:
TextUI.getRootView
Returns:
the view/**
     * Fetches a View with the allocation of the associated
     * text component (i.e. the root of the hierarchy) that
     * can be traversed to determine how the model is being
     * represented spatially.
     * <p>
     * <strong>Warning:</strong> The View hierarchy can
     * be traversed from the root view, and other things
     * can be done as well.  Things done in this way cannot
     * be protected like simple method calls through the TextUI.
     * Therefore, proper operation in the presence of concurrency
     * must be arranged by any logic that calls this method!
     *
     * @param tc the text component for which this UI is installed
     * @return the view
     * @see TextUI#getRootView
     */
    public View getRootView(JTextComponent tc) {
        return rootView;
    }


    
Returns the string to be used as the tooltip at the passed in location.
This forwards the method onto the root View.
See Also:
getToolTipText.getToolTipText
View.getToolTipText
Since:
1.4/**
     * Returns the string to be used as the tooltip at the passed in location.
     * This forwards the method onto the root View.
     *
     * @see javax.swing.text.JTextComponent#getToolTipText
     * @see javax.swing.text.View#getToolTipText
     * @since 1.4
     */
    @SuppressWarnings("deprecation")
    public String getToolTipText(JTextComponent t, Point pt) {
        if (!painted) {
            return null;
        }
        Document doc = editor.getDocument();
        String tt = null;
        Rectangle alloc = getVisibleEditorRect();

        if (alloc != null) {
            if (doc instanceof AbstractDocument) {
                ((AbstractDocument)doc).readLock();
            }
            try {
                tt = rootView.getToolTipText(pt.x, pt.y, alloc);
            } finally {
                if (doc instanceof AbstractDocument) {
                    ((AbstractDocument)doc).readUnlock();
                }
            }
        }
        return tt;
    }

    // --- ViewFactory methods ------------------------------

    
Creates a view for an element.
If a subclass wishes to directly implement the factory
producing the view(s), it should reimplement this
method.  By default it simply returns null indicating
it is unable to represent the element.
Params:
elem – the element
Returns:
the view/**
     * Creates a view for an element.
     * If a subclass wishes to directly implement the factory
     * producing the view(s), it should reimplement this
     * method.  By default it simply returns null indicating
     * it is unable to represent the element.
     *
     * @param elem the element
     * @return the view
     */
    public View create(Element elem) {
        return null;
    }

    
Creates a view for an element.
If a subclass wishes to directly implement the factory
producing the view(s), it should reimplement this
method.  By default it simply returns null indicating
it is unable to represent the part of the element.
Params:
elem – the element
p0 – the starting offset >= 0
p1 – the ending offset >= p0
Returns:
the view/**
     * Creates a view for an element.
     * If a subclass wishes to directly implement the factory
     * producing the view(s), it should reimplement this
     * method.  By default it simply returns null indicating
     * it is unable to represent the part of the element.
     *
     * @param elem the element
     * @param p0 the starting offset &gt;= 0
     * @param p1 the ending offset &gt;= p0
     * @return the view
     */
    public View create(Element elem, int p0, int p1) {
        return null;
    }

    
Default implementation of the interface Caret. /**
     * Default implementation of the interface {@code Caret}.
     */
    public static class BasicCaret extends DefaultCaret implements UIResource {}

    
Default implementation of the interface Highlighter. /**
     * Default implementation of the interface {@code Highlighter}.
     */
    public static class BasicHighlighter extends DefaultHighlighter implements UIResource {}

    static class BasicCursor extends Cursor implements UIResource {
        BasicCursor(int type) {
            super(type);
        }

        BasicCursor(String name) {
            super(name);
        }
    }

    private static BasicCursor textCursor = new BasicCursor(Cursor.TEXT_CURSOR);
    // ----- member variables ---------------------------------------

    private static final EditorKit defaultKit = new DefaultEditorKit();
    transient JTextComponent editor;
    transient boolean painted;
    transient RootView rootView = new RootView();
    transient UpdateHandler updateHandler = new UpdateHandler();
    private static final TransferHandler defaultTransferHandler = new TextTransferHandler();
    private final DragListener dragListener = getDragListener();
    private static final Position.Bias[] discardBias = new Position.Bias[1];
    private DefaultCaret dropCaret;
    private int caretMargin;

    
Root view that acts as a gateway between the component
and the View hierarchy.
/**
     * Root view that acts as a gateway between the component
     * and the View hierarchy.
     */
    class RootView extends View {

        RootView() {
            super(null);
        }

        void setView(View v) {
            View oldView = view;
            view = null;
            if (oldView != null) {
                // get rid of back reference so that the old
                // hierarchy can be garbage collected.
                oldView.setParent(null);
            }
            if (v != null) {
                v.setParent(this);
            }
            view = v;
        }

        
Fetches the attributes to use when rendering.  At the root
level there are no attributes.  If an attribute is resolved
up the view hierarchy this is the end of the line.
/**
         * Fetches the attributes to use when rendering.  At the root
         * level there are no attributes.  If an attribute is resolved
         * up the view hierarchy this is the end of the line.
         */
        public AttributeSet getAttributes() {
            return null;
        }

        
Determines the preferred span for this view along an axis.
Params:
axis – may be either X_AXIS or Y_AXIS
Returns:
the span the view would like to be rendered into.
        Typically the view is told to render into the span
        that is returned, although there is no guarantee.
        The parent may choose to resize or break the view./**
         * Determines the preferred span for this view along an axis.
         *
         * @param axis may be either X_AXIS or Y_AXIS
         * @return the span the view would like to be rendered into.
         *         Typically the view is told to render into the span
         *         that is returned, although there is no guarantee.
         *         The parent may choose to resize or break the view.
         */
        public float getPreferredSpan(int axis) {
            if (view != null) {
                return view.getPreferredSpan(axis);
            }
            return 10;
        }

        
Determines the minimum span for this view along an axis.
Params:
axis – may be either X_AXIS or Y_AXIS
Returns:
the span the view would like to be rendered into.
        Typically the view is told to render into the span
        that is returned, although there is no guarantee.
        The parent may choose to resize or break the view./**
         * Determines the minimum span for this view along an axis.
         *
         * @param axis may be either X_AXIS or Y_AXIS
         * @return the span the view would like to be rendered into.
         *         Typically the view is told to render into the span
         *         that is returned, although there is no guarantee.
         *         The parent may choose to resize or break the view.
         */
        public float getMinimumSpan(int axis) {
            if (view != null) {
                return view.getMinimumSpan(axis);
            }
            return 10;
        }

        
Determines the maximum span for this view along an axis.
Params:
axis – may be either X_AXIS or Y_AXIS
Returns:
the span the view would like to be rendered into.
        Typically the view is told to render into the span
        that is returned, although there is no guarantee.
        The parent may choose to resize or break the view./**
         * Determines the maximum span for this view along an axis.
         *
         * @param axis may be either X_AXIS or Y_AXIS
         * @return the span the view would like to be rendered into.
         *         Typically the view is told to render into the span
         *         that is returned, although there is no guarantee.
         *         The parent may choose to resize or break the view.
         */
        public float getMaximumSpan(int axis) {
            return Integer.MAX_VALUE;
        }

        
Specifies that a preference has changed.
Child views can call this on the parent to indicate that
the preference has changed.  The root view routes this to
invalidate on the hosting component.

This can be called on a different thread from the
event dispatching thread and is basically unsafe to
propagate into the component.  To make this safe,
the operation is transferred over to the event dispatching
thread for completion.  It is a design goal that all view
methods be safe to call without concern for concurrency,
and this behavior helps make that true.
Params:
child – the child view
width – true if the width preference has changed
height – true if the height preference has changed/**
         * Specifies that a preference has changed.
         * Child views can call this on the parent to indicate that
         * the preference has changed.  The root view routes this to
         * invalidate on the hosting component.
         * <p>
         * This can be called on a different thread from the
         * event dispatching thread and is basically unsafe to
         * propagate into the component.  To make this safe,
         * the operation is transferred over to the event dispatching
         * thread for completion.  It is a design goal that all view
         * methods be safe to call without concern for concurrency,
         * and this behavior helps make that true.
         *
         * @param child the child view
         * @param width true if the width preference has changed
         * @param height true if the height preference has changed
         */
        public void preferenceChanged(View child, boolean width, boolean height) {
            editor.revalidate();
        }

        
Determines the desired alignment for this view along an axis.
Params:
axis – may be either X_AXIS or Y_AXIS
Returns:
the desired alignment, where 0.0 indicates the origin
    and 1.0 the full span away from the origin/**
         * Determines the desired alignment for this view along an axis.
         *
         * @param axis may be either X_AXIS or Y_AXIS
         * @return the desired alignment, where 0.0 indicates the origin
         *     and 1.0 the full span away from the origin
         */
        public float getAlignment(int axis) {
            if (view != null) {
                return view.getAlignment(axis);
            }
            return 0;
        }

        
Renders the view.
Params:
g – the graphics context
allocation – the region to render into/**
         * Renders the view.
         *
         * @param g the graphics context
         * @param allocation the region to render into
         */
        public void paint(Graphics g, Shape allocation) {
            if (view != null) {
                Rectangle alloc = (allocation instanceof Rectangle) ?
                          (Rectangle)allocation : allocation.getBounds();
                setSize(alloc.width, alloc.height);
                view.paint(g, allocation);
            }
        }

        
Sets the view parent.
Params:
parent – the parent view/**
         * Sets the view parent.
         *
         * @param parent the parent view
         */
        public void setParent(View parent) {
            throw new Error("Can't set parent on root view");
        }

        
Returns the number of views in this view.  Since
this view simply wraps the root of the view hierarchy
it has exactly one child.
See Also:
getView
Returns:
the number of views/**
         * Returns the number of views in this view.  Since
         * this view simply wraps the root of the view hierarchy
         * it has exactly one child.
         *
         * @return the number of views
         * @see #getView
         */
        public int getViewCount() {
            return 1;
        }

        
Gets the n-th view in this container.
Params:
n – the number of the view to get
Returns:
the view/**
         * Gets the n-th view in this container.
         *
         * @param n the number of the view to get
         * @return the view
         */
        public View getView(int n) {
            return view;
        }

        
Returns the child view index representing the given position in
the model.  This is implemented to return the index of the only
child.
Params:
pos – the position >= 0
Returns:
 index of the view representing the given position, or
  -1 if no view represents that position
Since:
1.3/**
         * Returns the child view index representing the given position in
         * the model.  This is implemented to return the index of the only
         * child.
         *
         * @param pos the position &gt;= 0
         * @return  index of the view representing the given position, or
         *   -1 if no view represents that position
         * @since 1.3
         */
        public int getViewIndex(int pos, Position.Bias b) {
            return 0;
        }

        
Fetches the allocation for the given child view.
This enables finding out where various views
are located, without assuming the views store
their location.  This returns the given allocation
since this view simply acts as a gateway between
the view hierarchy and the associated component.
Params:
index – the index of the child
a –  the allocation to this view.
Returns:
the allocation to the child/**
         * Fetches the allocation for the given child view.
         * This enables finding out where various views
         * are located, without assuming the views store
         * their location.  This returns the given allocation
         * since this view simply acts as a gateway between
         * the view hierarchy and the associated component.
         *
         * @param index the index of the child
         * @param a  the allocation to this view.
         * @return the allocation to the child
         */
        public Shape getChildAllocation(int index, Shape a) {
            return a;
        }

        
Provides a mapping from the document model coordinate space
to the coordinate space of the view mapped to it.
Params:
pos – the position to convert
a – the allocated region to render into
Returns:
the bounding box of the given position/**
         * Provides a mapping from the document model coordinate space
         * to the coordinate space of the view mapped to it.
         *
         * @param pos the position to convert
         * @param a the allocated region to render into
         * @return the bounding box of the given position
         */
        public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
            if (view != null) {
                return view.modelToView(pos, a, b);
            }
            return null;
        }

        
Provides a mapping from the document model coordinate space
to the coordinate space of the view mapped to it.
Params:
p0 – the position to convert >= 0
b0 – the bias toward the previous character or the
 next character represented by p0, in case the
 position is a boundary of two views.
p1 – the position to convert >= 0
b1 – the bias toward the previous character or the
 next character represented by p1, in case the
 position is a boundary of two views.
a – the allocated region to render into
Throws:
BadLocationException –  if the given position does
  not represent a valid location in the associated document
IllegalArgumentException – for an invalid bias argument
See Also:
View.viewToModel
Returns:
the bounding box of the given position is returned/**
         * Provides a mapping from the document model coordinate space
         * to the coordinate space of the view mapped to it.
         *
         * @param p0 the position to convert &gt;= 0
         * @param b0 the bias toward the previous character or the
         *  next character represented by p0, in case the
         *  position is a boundary of two views.
         * @param p1 the position to convert &gt;= 0
         * @param b1 the bias toward the previous character or the
         *  next character represented by p1, in case the
         *  position is a boundary of two views.
         * @param a the allocated region to render into
         * @return the bounding box of the given position is returned
         * @exception BadLocationException  if the given position does
         *   not represent a valid location in the associated document
         * @exception IllegalArgumentException for an invalid bias argument
         * @see View#viewToModel
         */
        public Shape modelToView(int p0, Position.Bias b0, int p1, Position.Bias b1, Shape a) throws BadLocationException {
            if (view != null) {
                return view.modelToView(p0, b0, p1, b1, a);
            }
            return null;
        }

        
Provides a mapping from the view coordinate space to the logical
coordinate space of the model.
Params:
x – x coordinate of the view location to convert
y – y coordinate of the view location to convert
a – the allocated region to render into
Returns:
the location within the model that best represents the
   given point in the view/**
         * Provides a mapping from the view coordinate space to the logical
         * coordinate space of the model.
         *
         * @param x x coordinate of the view location to convert
         * @param y y coordinate of the view location to convert
         * @param a the allocated region to render into
         * @return the location within the model that best represents the
         *    given point in the view
         */
        public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {
            if (view != null) {
                int retValue = view.viewToModel(x, y, a, bias);
                return retValue;
            }
            return -1;
        }

        
Provides a way to determine the next visually represented model location that one might place a caret. Some views may not be visible, they might not be in the same order found in the model, or they just might not allow access to some of the locations in the model. This method enables specifying a position to convert within the range of >=0. If the value is -1, a position will be calculated automatically. If the value < -1, the BadLocationException will be thrown. 
Params:
pos – the position to convert >= 0
a – the allocated region to render into
direction – the direction from the current position that can
 be thought of as the arrow keys typically found on a keyboard.
 This may be SwingConstants.WEST, SwingConstants.EAST,
 SwingConstants.NORTH, or SwingConstants.SOUTH.
Throws:
BadLocationException – the given position is not a valid
                                position within the document
IllegalArgumentException – for an invalid direction
Returns:
the location within the model that best represents the next
 location visual position./**
         * Provides a way to determine the next visually represented model
         * location that one might place a caret.  Some views may not be visible,
         * they might not be in the same order found in the model, or they just
         * might not allow access to some of the locations in the model.
         * This method enables specifying a position to convert
         * within the range of &gt;=0.  If the value is -1, a position
         * will be calculated automatically.  If the value &lt; -1,
         * the {@code BadLocationException} will be thrown.
         *
         * @param pos the position to convert &gt;= 0
         * @param a the allocated region to render into
         * @param direction the direction from the current position that can
         *  be thought of as the arrow keys typically found on a keyboard.
         *  This may be SwingConstants.WEST, SwingConstants.EAST,
         *  SwingConstants.NORTH, or SwingConstants.SOUTH.
         * @return the location within the model that best represents the next
         *  location visual position.
         * @exception BadLocationException the given position is not a valid
         *                                 position within the document
         * @exception IllegalArgumentException for an invalid direction
         */
        public int getNextVisualPositionFrom(int pos, Position.Bias b, Shape a,
                                             int direction,
                                             Position.Bias[] biasRet)
            throws BadLocationException {
            if (pos < -1 || pos > getDocument().getLength()) {
                throw new BadLocationException("invalid position", pos);
            }
            if( view != null ) {
                int nextPos = view.getNextVisualPositionFrom(pos, b, a,
                                                     direction, biasRet);
                if(nextPos != -1) {
                    pos = nextPos;
                }
                else {
                    biasRet[0] = b;
                }
            }
            return pos;
        }

        
Gives notification that something was inserted into the document
in a location that this view is responsible for.
Params:
e – the change information from the associated document
a – the current allocation of the view
f – the factory to use to rebuild if the view has children/**
         * Gives notification that something was inserted into the document
         * in a location that this view is responsible for.
         *
         * @param e the change information from the associated document
         * @param a the current allocation of the view
         * @param f the factory to use to rebuild if the view has children
         */
        public void insertUpdate(DocumentEvent e, Shape a, ViewFactory f) {
            if (view != null) {
                view.insertUpdate(e, a, f);
            }
        }

        
Gives notification that something was removed from the document
in a location that this view is responsible for.
Params:
e – the change information from the associated document
a – the current allocation of the view
f – the factory to use to rebuild if the view has children/**
         * Gives notification that something was removed from the document
         * in a location that this view is responsible for.
         *
         * @param e the change information from the associated document
         * @param a the current allocation of the view
         * @param f the factory to use to rebuild if the view has children
         */
        public void removeUpdate(DocumentEvent e, Shape a, ViewFactory f) {
            if (view != null) {
                view.removeUpdate(e, a, f);
            }
        }

        
Gives notification from the document that attributes were changed
in a location that this view is responsible for.
Params:
e – the change information from the associated document
a – the current allocation of the view
f – the factory to use to rebuild if the view has children/**
         * Gives notification from the document that attributes were changed
         * in a location that this view is responsible for.
         *
         * @param e the change information from the associated document
         * @param a the current allocation of the view
         * @param f the factory to use to rebuild if the view has children
         */
        public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {
            if (view != null) {
                view.changedUpdate(e, a, f);
            }
        }

        
Returns the document model underlying the view.
Returns:
the model/**
         * Returns the document model underlying the view.
         *
         * @return the model
         */
        public Document getDocument() {
            return editor.getDocument();
        }

        
Returns the starting offset into the model for this view.
Returns:
the starting offset/**
         * Returns the starting offset into the model for this view.
         *
         * @return the starting offset
         */
        public int getStartOffset() {
            if (view != null) {
                return view.getStartOffset();
            }
            return getElement().getStartOffset();
        }

        
Returns the ending offset into the model for this view.
Returns:
the ending offset/**
         * Returns the ending offset into the model for this view.
         *
         * @return the ending offset
         */
        public int getEndOffset() {
            if (view != null) {
                return view.getEndOffset();
            }
            return getElement().getEndOffset();
        }

        
Gets the element that this view is mapped to.
Returns:
the view/**
         * Gets the element that this view is mapped to.
         *
         * @return the view
         */
        public Element getElement() {
            if (view != null) {
                return view.getElement();
            }
            return editor.getDocument().getDefaultRootElement();
        }

        
Breaks this view on the given axis at the given length.
Params:
axis – may be either X_AXIS or Y_AXIS
len – specifies where a break is desired in the span
a – the current allocation of the view
Returns:
the fragment of the view that represents the given span
  if the view can be broken, otherwise null/**
         * Breaks this view on the given axis at the given length.
         *
         * @param axis may be either X_AXIS or Y_AXIS
         * @param len specifies where a break is desired in the span
         * @param a the current allocation of the view
         * @return the fragment of the view that represents the given span
         *   if the view can be broken, otherwise null
         */
        public View breakView(int axis, float len, Shape a) {
            throw new Error("Can't break root view");
        }

        
Determines the resizability of the view along the
given axis.  A value of 0 or less is not resizable.
Params:
axis – may be either X_AXIS or Y_AXIS
Returns:
the weight/**
         * Determines the resizability of the view along the
         * given axis.  A value of 0 or less is not resizable.
         *
         * @param axis may be either X_AXIS or Y_AXIS
         * @return the weight
         */
        public int getResizeWeight(int axis) {
            if (view != null) {
                return view.getResizeWeight(axis);
            }
            return 0;
        }

        
Sets the view size.
Params:
width – the width
height – the height/**
         * Sets the view size.
         *
         * @param width the width
         * @param height the height
         */
        public void setSize(float width, float height) {
            if (view != null) {
                view.setSize(width, height);
            }
        }

        
Fetches the container hosting the view.  This is useful for
things like scheduling a repaint, finding out the host
components font, etc.  The default implementation
of this is to forward the query to the parent view.
Returns:
the container/**
         * Fetches the container hosting the view.  This is useful for
         * things like scheduling a repaint, finding out the host
         * components font, etc.  The default implementation
         * of this is to forward the query to the parent view.
         *
         * @return the container
         */
        public Container getContainer() {
            return editor;
        }

        
Fetches the factory to be used for building the
various view fragments that make up the view that
represents the model.  This is what determines
how the model will be represented.  This is implemented
to fetch the factory provided by the associated
EditorKit unless that is null, in which case this
simply returns the BasicTextUI itself which allows
subclasses to implement a simple factory directly without
creating extra objects.
Returns:
the factory/**
         * Fetches the factory to be used for building the
         * various view fragments that make up the view that
         * represents the model.  This is what determines
         * how the model will be represented.  This is implemented
         * to fetch the factory provided by the associated
         * EditorKit unless that is null, in which case this
         * simply returns the BasicTextUI itself which allows
         * subclasses to implement a simple factory directly without
         * creating extra objects.
         *
         * @return the factory
         */
        public ViewFactory getViewFactory() {
            EditorKit kit = getEditorKit(editor);
            ViewFactory f = kit.getViewFactory();
            if (f != null) {
                return f;
            }
            return BasicTextUI.this;
        }

        private View view;

    }

    
Handles updates from various places.  If the model is changed,
this class unregisters as a listener to the old model and
registers with the new model.  If the document model changes,
the change is forwarded to the root view.  If the focus
accelerator changes, a new keystroke is registered to request
focus.
/**
     * Handles updates from various places.  If the model is changed,
     * this class unregisters as a listener to the old model and
     * registers with the new model.  If the document model changes,
     * the change is forwarded to the root view.  If the focus
     * accelerator changes, a new keystroke is registered to request
     * focus.
     */
    class UpdateHandler implements PropertyChangeListener, DocumentListener, LayoutManager2, UIResource {

        // --- PropertyChangeListener methods -----------------------

        
This method gets called when a bound property is changed.
We are looking for document changes on the editor.
/**
         * This method gets called when a bound property is changed.
         * We are looking for document changes on the editor.
         */
        public final void propertyChange(PropertyChangeEvent evt) {
            Object oldValue = evt.getOldValue();
            Object newValue = evt.getNewValue();
            String propertyName = evt.getPropertyName();
            if ((oldValue instanceof Document) || (newValue instanceof Document)) {
                if (oldValue != null) {
                    ((Document)oldValue).removeDocumentListener(this);
                    i18nView = false;
                }
                if (newValue != null) {
                    ((Document)newValue).addDocumentListener(this);
                    if ("document" == propertyName) {
                        setView(null);
                        BasicTextUI.this.propertyChange(evt);
                        modelChanged();
                        return;
                    }
                }
                modelChanged();
            }
            if ("focusAccelerator" == propertyName) {
                updateFocusAcceleratorBinding(true);
            } else if ("componentOrientation" == propertyName) {
                // Changes in ComponentOrientation require the views to be
                // rebuilt.
                modelChanged();
            } else if ("font" == propertyName) {
                modelChanged();
            } else if ("dropLocation" == propertyName) {
                dropIndexChanged();
            } else if ("editable" == propertyName) {
                updateCursor();
                modelChanged();
            }
            BasicTextUI.this.propertyChange(evt);
        }

        private void dropIndexChanged() {
            if (editor.getDropMode() == DropMode.USE_SELECTION) {
                return;
            }

            JTextComponent.DropLocation dropLocation = editor.getDropLocation();

            if (dropLocation == null) {
                if (dropCaret != null) {
                    dropCaret.deinstall(editor);
                    editor.repaint(dropCaret);
                    dropCaret = null;
                }
            } else {
                if (dropCaret == null) {
                    dropCaret = new BasicCaret();
                    dropCaret.install(editor);
                    dropCaret.setVisible(true);
                }

                dropCaret.setDot(dropLocation.getIndex(),
                                 dropLocation.getBias());
            }
        }

        // --- DocumentListener methods -----------------------

        
The insert notification.  Gets sent to the root of the view structure
that represents the portion of the model being represented by the
editor.  The factory is added as an argument to the update so that
the views can update themselves in a dynamic (not hardcoded) way.
Params:
e –  The change notification from the currently associated
 document.
See Also:
DocumentListener.insertUpdate/**
         * The insert notification.  Gets sent to the root of the view structure
         * that represents the portion of the model being represented by the
         * editor.  The factory is added as an argument to the update so that
         * the views can update themselves in a dynamic (not hardcoded) way.
         *
         * @param e  The change notification from the currently associated
         *  document.
         * @see DocumentListener#insertUpdate
         */
        public final void insertUpdate(DocumentEvent e) {
            Document doc = e.getDocument();
            Object o = doc.getProperty("i18n");
            if (o instanceof Boolean) {
                Boolean i18nFlag = (Boolean) o;
                if (i18nFlag.booleanValue() != i18nView) {
                    // i18n flag changed, rebuild the view
                    i18nView = i18nFlag.booleanValue();
                    modelChanged();
                    return;
                }
            }

            // normal insert update
            Rectangle alloc = (painted) ? getVisibleEditorRect() : null;
            rootView.insertUpdate(e, alloc, rootView.getViewFactory());
        }

        
The remove notification.  Gets sent to the root of the view structure
that represents the portion of the model being represented by the
editor.  The factory is added as an argument to the update so that
the views can update themselves in a dynamic (not hardcoded) way.
Params:
e –  The change notification from the currently associated
 document.
See Also:
DocumentListener.removeUpdate/**
         * The remove notification.  Gets sent to the root of the view structure
         * that represents the portion of the model being represented by the
         * editor.  The factory is added as an argument to the update so that
         * the views can update themselves in a dynamic (not hardcoded) way.
         *
         * @param e  The change notification from the currently associated
         *  document.
         * @see DocumentListener#removeUpdate
         */
        public final void removeUpdate(DocumentEvent e) {
            Rectangle alloc = (painted) ? getVisibleEditorRect() : null;
            rootView.removeUpdate(e, alloc, rootView.getViewFactory());
        }

        
The change notification.  Gets sent to the root of the view structure
that represents the portion of the model being represented by the
editor.  The factory is added as an argument to the update so that
the views can update themselves in a dynamic (not hardcoded) way.
Params:
e –  The change notification from the currently associated
 document.
See Also:
DocumentListener.changedUpdate(DocumentEvent)/**
         * The change notification.  Gets sent to the root of the view structure
         * that represents the portion of the model being represented by the
         * editor.  The factory is added as an argument to the update so that
         * the views can update themselves in a dynamic (not hardcoded) way.
         *
         * @param e  The change notification from the currently associated
         *  document.
         * @see DocumentListener#changedUpdate(DocumentEvent)
         */
        public final void changedUpdate(DocumentEvent e) {
            Rectangle alloc = (painted) ? getVisibleEditorRect() : null;
            rootView.changedUpdate(e, alloc, rootView.getViewFactory());
        }

        // --- LayoutManager2 methods --------------------------------

        
Adds the specified component with the specified name to
the layout.
Params:
name – the component name
comp – the component to be added/**
         * Adds the specified component with the specified name to
         * the layout.
         * @param name the component name
         * @param comp the component to be added
         */
        public void addLayoutComponent(String name, Component comp) {
            // not supported
        }

        
Removes the specified component from the layout.
Params:
comp – the component to be removed/**
         * Removes the specified component from the layout.
         * @param comp the component to be removed
         */
        public void removeLayoutComponent(Component comp) {
            if (constraints != null) {
                // remove the constraint record
                constraints.remove(comp);
            }
        }

        
Calculates the preferred size dimensions for the specified
panel given the components in the specified parent container.
Params:
parent – the component to be laid out
See Also:
minimumLayoutSize/**
         * Calculates the preferred size dimensions for the specified
         * panel given the components in the specified parent container.
         * @param parent the component to be laid out
         *
         * @see #minimumLayoutSize
         */
        public Dimension preferredLayoutSize(Container parent) {
            // should not be called (JComponent uses UI instead)
            return null;
        }

        
Calculates the minimum size dimensions for the specified
panel given the components in the specified parent container.
Params:
parent – the component to be laid out
See Also:
preferredLayoutSize/**
         * Calculates the minimum size dimensions for the specified
         * panel given the components in the specified parent container.
         * @param parent the component to be laid out
         * @see #preferredLayoutSize
         */
        public Dimension minimumLayoutSize(Container parent) {
            // should not be called (JComponent uses UI instead)
            return null;
        }

        
Lays out the container in the specified panel.  This is
implemented to position all components that were added
with a View object as a constraint.  The current allocation
of the associated View is used as the location of the
component.

A read-lock is acquired on the document to prevent the
view tree from being modified while the layout process
is active.
Params:
parent – the component which needs to be laid out/**
         * Lays out the container in the specified panel.  This is
         * implemented to position all components that were added
         * with a View object as a constraint.  The current allocation
         * of the associated View is used as the location of the
         * component.
         * <p>
         * A read-lock is acquired on the document to prevent the
         * view tree from being modified while the layout process
         * is active.
         *
         * @param parent the component which needs to be laid out
         */
        public void layoutContainer(Container parent) {
            if ((constraints != null) && (! constraints.isEmpty())) {
                Rectangle alloc = getVisibleEditorRect();
                if (alloc != null) {
                    Document doc = editor.getDocument();
                    if (doc instanceof AbstractDocument) {
                        ((AbstractDocument)doc).readLock();
                    }
                    try {
                        rootView.setSize(alloc.width, alloc.height);
                        Enumeration<Component> components = constraints.keys();
                        while (components.hasMoreElements()) {
                            Component comp = components.nextElement();
                            View v = (View) constraints.get(comp);
                            Shape ca = calculateViewPosition(alloc, v);
                            if (ca != null) {
                                Rectangle compAlloc = (ca instanceof Rectangle) ?
                                    (Rectangle) ca : ca.getBounds();
                                comp.setBounds(compAlloc);
                            }
                        }
                    } finally {
                        if (doc instanceof AbstractDocument) {
                            ((AbstractDocument)doc).readUnlock();
                        }
                    }
                }
            }
        }

        
Find the Shape representing the given view.
/**
         * Find the Shape representing the given view.
         */
        Shape calculateViewPosition(Shape alloc, View v) {
            int pos = v.getStartOffset();
            View child = null;
            for (View parent = rootView; (parent != null) && (parent != v); parent = child) {
                int index = parent.getViewIndex(pos, Position.Bias.Forward);
                alloc = parent.getChildAllocation(index, alloc);
                child = parent.getView(index);
            }
            return (child != null) ? alloc : null;
        }

        
Adds the specified component to the layout, using the specified
constraint object.  We only store those components that were added
with a constraint that is of type View.
Params:
comp – the component to be added
constraint –  where/how the component is added to the layout./**
         * Adds the specified component to the layout, using the specified
         * constraint object.  We only store those components that were added
         * with a constraint that is of type View.
         *
         * @param comp the component to be added
         * @param constraint  where/how the component is added to the layout.
         */
        public void addLayoutComponent(Component comp, Object constraint) {
            if (constraint instanceof View) {
                if (constraints == null) {
                    constraints = new Hashtable<Component, Object>(7);
                }
                constraints.put(comp, constraint);
            }
        }

        
Returns the maximum size of this component.
See Also:
getMinimumSize.getMinimumSize()
Component.getPreferredSize()
LayoutManager/**
         * Returns the maximum size of this component.
         * @see java.awt.Component#getMinimumSize()
         * @see java.awt.Component#getPreferredSize()
         * @see LayoutManager
         */
        public Dimension maximumLayoutSize(Container target) {
            // should not be called (JComponent uses UI instead)
            return null;
        }

        
Returns the alignment along the x axis.  This specifies how
the component would like to be aligned relative to other
components.  The value should be a number between 0 and 1
where 0 represents alignment along the origin, 1 is aligned
the furthest away from the origin, 0.5 is centered, etc.
/**
         * Returns the alignment along the x axis.  This specifies how
         * the component would like to be aligned relative to other
         * components.  The value should be a number between 0 and 1
         * where 0 represents alignment along the origin, 1 is aligned
         * the furthest away from the origin, 0.5 is centered, etc.
         */
        public float getLayoutAlignmentX(Container target) {
            return 0.5f;
        }

        
Returns the alignment along the y axis.  This specifies how
the component would like to be aligned relative to other
components.  The value should be a number between 0 and 1
where 0 represents alignment along the origin, 1 is aligned
the furthest away from the origin, 0.5 is centered, etc.
/**
         * Returns the alignment along the y axis.  This specifies how
         * the component would like to be aligned relative to other
         * components.  The value should be a number between 0 and 1
         * where 0 represents alignment along the origin, 1 is aligned
         * the furthest away from the origin, 0.5 is centered, etc.
         */
        public float getLayoutAlignmentY(Container target) {
            return 0.5f;
        }

        
Invalidates the layout, indicating that if the layout manager
has cached information it should be discarded.
/**
         * Invalidates the layout, indicating that if the layout manager
         * has cached information it should be discarded.
         */
        public void invalidateLayout(Container target) {
        }

        
The "layout constraints" for the LayoutManager2 implementation.
These are View objects for those components that are represented
by a View in the View tree.
/**
         * The "layout constraints" for the LayoutManager2 implementation.
         * These are View objects for those components that are represented
         * by a View in the View tree.
         */
        private Hashtable<Component, Object> constraints;

        private boolean i18nView = false;
    }

    
Wrapper for text actions to return isEnabled false in case editor is non editable
/**
     * Wrapper for text actions to return isEnabled false in case editor is non editable
     */
    class TextActionWrapper extends TextAction {
        public TextActionWrapper(TextAction action) {
            super((String)action.getValue(Action.NAME));
            this.action = action;
        }
        
The operation to perform when this action is triggered.
Params:
e – the action event/**
         * The operation to perform when this action is triggered.
         *
         * @param e the action event
         */
        public void actionPerformed(ActionEvent e) {
            action.actionPerformed(e);
        }
        public boolean isEnabled() {
            return (editor == null || editor.isEditable()) ? action.isEnabled() : false;
        }
        TextAction action = null;
    }


    
Registered in the ActionMap.
/**
     * Registered in the ActionMap.
     */
    class FocusAction extends AbstractAction {

        public void actionPerformed(ActionEvent e) {
            editor.requestFocus();
        }

        public boolean isEnabled() {
            return editor.isEditable();
        }
    }

    private static DragListener getDragListener() {
        synchronized(DragListener.class) {
            DragListener listener =
                (DragListener)AppContext.getAppContext().
                    get(DragListener.class);

            if (listener == null) {
                listener = new DragListener();
                AppContext.getAppContext().put(DragListener.class, listener);
            }

            return listener;
        }
    }

    
Listens for mouse events for the purposes of detecting drag gestures.
BasicTextUI will maintain one of these per AppContext.
/**
     * Listens for mouse events for the purposes of detecting drag gestures.
     * BasicTextUI will maintain one of these per AppContext.
     */
    static class DragListener extends MouseInputAdapter
                              implements BeforeDrag {

        private boolean dragStarted;

        public void dragStarting(MouseEvent me) {
            dragStarted = true;
        }

        public void mousePressed(MouseEvent e) {
            JTextComponent c = (JTextComponent)e.getSource();
            if (c.getDragEnabled()) {
                dragStarted = false;
                if (isDragPossible(e) && DragRecognitionSupport.mousePressed(e)) {
                    e.consume();
                }
            }
        }

        public void mouseReleased(MouseEvent e) {
            JTextComponent c = (JTextComponent)e.getSource();
            if (c.getDragEnabled()) {
                if (dragStarted) {
                    e.consume();
                }

                DragRecognitionSupport.mouseReleased(e);
            }
        }

        public void mouseDragged(MouseEvent e) {
            JTextComponent c = (JTextComponent)e.getSource();
            if (c.getDragEnabled()) {
                if (dragStarted || DragRecognitionSupport.mouseDragged(e, this)) {
                    e.consume();
                }
            }
        }

        
Determines if the following are true:

the component is enabled
the press event is located over a selection

/**
         * Determines if the following are true:
         * <ul>
         * <li>the component is enabled
         * <li>the press event is located over a selection
         * </ul>
         */
        @SuppressWarnings("deprecation")
        protected boolean isDragPossible(MouseEvent e) {
            JTextComponent c = (JTextComponent)e.getSource();
            if (c.isEnabled()) {
                Caret caret = c.getCaret();
                int dot = caret.getDot();
                int mark = caret.getMark();
                if (dot != mark) {
                    Point p = new Point(e.getX(), e.getY());
                    int pos = c.viewToModel(p);

                    int p0 = Math.min(dot, mark);
                    int p1 = Math.max(dot, mark);
                    if ((pos >= p0) && (pos < p1)) {
                        return true;
                    }
                }
            }
            return false;
        }
    }

    static class TextTransferHandler extends TransferHandler implements UIResource {

        private JTextComponent exportComp;
        private boolean shouldRemove;
        private int p0;
        private int p1;

        
Whether or not this is a drop using
DropMode.INSERT.
/**
         * Whether or not this is a drop using
         * <code>DropMode.INSERT</code>.
         */
        private boolean modeBetween = false;

        
Whether or not this is a drop.
/**
         * Whether or not this is a drop.
         */
        private boolean isDrop = false;

        
The drop action.
/**
         * The drop action.
         */
        private int dropAction = MOVE;

        
The drop bias.
/**
         * The drop bias.
         */
        private Position.Bias dropBias;

        
Try to find a flavor that can be used to import a Transferable.
The set of usable flavors are tried in the following order:

    
First, an attempt is made to find a flavor matching the content type
        of the EditorKit for the component.
    
Second, an attempt to find a text/plain flavor is made.
    
Third, an attempt to find a flavor representing a String reference
        in the same VM is made.
    
Lastly, DataFlavor.stringFlavor is searched for.

/**
         * Try to find a flavor that can be used to import a Transferable.
         * The set of usable flavors are tried in the following order:
         * <ol>
         *     <li>First, an attempt is made to find a flavor matching the content type
         *         of the EditorKit for the component.
         *     <li>Second, an attempt to find a text/plain flavor is made.
         *     <li>Third, an attempt to find a flavor representing a String reference
         *         in the same VM is made.
         *     <li>Lastly, DataFlavor.stringFlavor is searched for.
         * </ol>
         */
        protected DataFlavor getImportFlavor(DataFlavor[] flavors, JTextComponent c) {
            DataFlavor plainFlavor = null;
            DataFlavor refFlavor = null;
            DataFlavor stringFlavor = null;

            if (c instanceof JEditorPane) {
                for (int i = 0; i < flavors.length; i++) {
                    String mime = flavors[i].getMimeType();
                    if (mime.startsWith(((JEditorPane)c).getEditorKit().getContentType())) {
                        return flavors[i];
                    } else if (plainFlavor == null && mime.startsWith("text/plain")) {
                        plainFlavor = flavors[i];
                    } else if (refFlavor == null && mime.startsWith("application/x-java-jvm-local-objectref")
                                                 && flavors[i].getRepresentationClass() == java.lang.String.class) {
                        refFlavor = flavors[i];
                    } else if (stringFlavor == null && flavors[i].equals(DataFlavor.stringFlavor)) {
                        stringFlavor = flavors[i];
                    }
                }
                if (plainFlavor != null) {
                    return plainFlavor;
                } else if (refFlavor != null) {
                    return refFlavor;
                } else if (stringFlavor != null) {
                    return stringFlavor;
                }
                return null;
            }


            for (int i = 0; i < flavors.length; i++) {
                String mime = flavors[i].getMimeType();
                if (mime.startsWith("text/plain")) {
                    return flavors[i];
                } else if (refFlavor == null && mime.startsWith("application/x-java-jvm-local-objectref")
                                             && flavors[i].getRepresentationClass() == java.lang.String.class) {
                    refFlavor = flavors[i];
                } else if (stringFlavor == null && flavors[i].equals(DataFlavor.stringFlavor)) {
                    stringFlavor = flavors[i];
                }
            }
            if (refFlavor != null) {
                return refFlavor;
            } else if (stringFlavor != null) {
                return stringFlavor;
            }
            return null;
        }

        
Import the given stream data into the text component.
/**
         * Import the given stream data into the text component.
         */
        protected void handleReaderImport(Reader in, JTextComponent c, boolean useRead)
                                               throws BadLocationException, IOException {
            if (useRead) {
                int startPosition = c.getSelectionStart();
                int endPosition = c.getSelectionEnd();
                int length = endPosition - startPosition;
                EditorKit kit = c.getUI().getEditorKit(c);
                Document doc = c.getDocument();
                if (length > 0) {
                    doc.remove(startPosition, length);
                }
                kit.read(in, doc, startPosition);
            } else {
                char[] buff = new char[1024];
                int nch;
                boolean lastWasCR = false;
                int last;
                StringBuffer sbuff = null;

                // Read in a block at a time, mapping \r\n to \n, as well as single
                // \r to \n.
                while ((nch = in.read(buff, 0, buff.length)) != -1) {
                    if (sbuff == null) {
                        sbuff = new StringBuffer(nch);
                    }
                    last = 0;
                    for(int counter = 0; counter < nch; counter++) {
                        switch(buff[counter]) {
                        case '\r':
                            if (lastWasCR) {
                                if (counter == 0) {
                                    sbuff.append('\n');
                                } else {
                                    buff[counter - 1] = '\n';
                                }
                            } else {
                                lastWasCR = true;
                            }
                            break;
                        case '\n':
                            if (lastWasCR) {
                                if (counter > (last + 1)) {
                                    sbuff.append(buff, last, counter - last - 1);
                                }
                                // else nothing to do, can skip \r, next write will
                                // write \n
                                lastWasCR = false;
                                last = counter;
                            }
                            break;
                        default:
                            if (lastWasCR) {
                                if (counter == 0) {
                                    sbuff.append('\n');
                                } else {
                                    buff[counter - 1] = '\n';
                                }
                                lastWasCR = false;
                            }
                            break;
                        }
                    }
                    if (last < nch) {
                        if (lastWasCR) {
                            if (last < (nch - 1)) {
                                sbuff.append(buff, last, nch - last - 1);
                            }
                        } else {
                            sbuff.append(buff, last, nch - last);
                        }
                    }
                }
                if (lastWasCR) {
                    sbuff.append('\n');
                }
                c.replaceSelection(sbuff != null ? sbuff.toString() : "");
            }
        }

        // --- TransferHandler methods ------------------------------------

        
This is the type of transfer actions supported by the source.  Some models are
not mutable, so a transfer operation of COPY only should
be advertised in that case.
Params:
c –  The component holding the data to be transfered.  This
 argument is provided to enable sharing of TransferHandlers by
 multiple components.
Returns:
 This is implemented to return NONE if the component is a JPasswordField
 since exporting data via user gestures is not allowed.  If the text component is
 editable, COPY_OR_MOVE is returned, otherwise just COPY is allowed./**
         * This is the type of transfer actions supported by the source.  Some models are
         * not mutable, so a transfer operation of COPY only should
         * be advertised in that case.
         *
         * @param c  The component holding the data to be transfered.  This
         *  argument is provided to enable sharing of TransferHandlers by
         *  multiple components.
         * @return  This is implemented to return NONE if the component is a JPasswordField
         *  since exporting data via user gestures is not allowed.  If the text component is
         *  editable, COPY_OR_MOVE is returned, otherwise just COPY is allowed.
         */
        public int getSourceActions(JComponent c) {
            if (c instanceof JPasswordField &&
                c.getClientProperty("JPasswordField.cutCopyAllowed") !=
                Boolean.TRUE) {
                return NONE;
            }

            return ((JTextComponent)c).isEditable() ? COPY_OR_MOVE : COPY;
        }

        
Create a Transferable to use as the source for a data transfer.
Params:
comp –  The component holding the data to be transfered.  This
 argument is provided to enable sharing of TransferHandlers by
 multiple components.
Returns:
 The representation of the data to be transfered./**
         * Create a Transferable to use as the source for a data transfer.
         *
         * @param comp  The component holding the data to be transfered.  This
         *  argument is provided to enable sharing of TransferHandlers by
         *  multiple components.
         * @return  The representation of the data to be transfered.
         *
         */
        protected Transferable createTransferable(JComponent comp) {
            exportComp = (JTextComponent)comp;
            shouldRemove = true;
            p0 = exportComp.getSelectionStart();
            p1 = exportComp.getSelectionEnd();
            return (p0 != p1) ? (new TextTransferable(exportComp, p0, p1)) : null;
        }

        
This method is called after data has been exported.  This method should remove
the data that was transfered if the action was MOVE.
Params:
source – The component that was the source of the data.
data –   The data that was transferred or possibly null
              if the action is NONE.
action – The actual action that was performed./**
         * This method is called after data has been exported.  This method should remove
         * the data that was transfered if the action was MOVE.
         *
         * @param source The component that was the source of the data.
         * @param data   The data that was transferred or possibly null
         *               if the action is <code>NONE</code>.
         * @param action The actual action that was performed.
         */
        protected void exportDone(JComponent source, Transferable data, int action) {
            // only remove the text if shouldRemove has not been set to
            // false by importData and only if the action is a move
            if (shouldRemove && action == MOVE) {
                TextTransferable t = (TextTransferable)data;
                t.removeText();
            }

            exportComp = null;
        }

        public boolean importData(TransferSupport support) {
            isDrop = support.isDrop();

            if (isDrop) {
                modeBetween =
                    ((JTextComponent)support.getComponent()).getDropMode() == DropMode.INSERT;

                dropBias = ((JTextComponent.DropLocation)support.getDropLocation()).getBias();

                dropAction = support.getDropAction();
            }

            try {
                return super.importData(support);
            } finally {
                isDrop = false;
                modeBetween = false;
                dropBias = null;
                dropAction = MOVE;
            }
        }

        
This method causes a transfer to a component from a clipboard or a
DND drop operation.  The Transferable represents the data to be
imported into the component.
Params:
comp –  The component to receive the transfer.  This
 argument is provided to enable sharing of TransferHandlers by
 multiple components.
t –     The data to import
Returns:
 true if the data was inserted into the component, false otherwise./**
         * This method causes a transfer to a component from a clipboard or a
         * DND drop operation.  The Transferable represents the data to be
         * imported into the component.
         *
         * @param comp  The component to receive the transfer.  This
         *  argument is provided to enable sharing of TransferHandlers by
         *  multiple components.
         * @param t     The data to import
         * @return  true if the data was inserted into the component, false otherwise.
         */
        public boolean importData(JComponent comp, Transferable t) {
            JTextComponent c = (JTextComponent)comp;

            int pos = modeBetween
                      ? c.getDropLocation().getIndex() : c.getCaretPosition();

            // if we are importing to the same component that we exported from
            // then don't actually do anything if the drop location is inside
            // the drag location and set shouldRemove to false so that exportDone
            // knows not to remove any data
            if (dropAction == MOVE && c == exportComp && pos >= p0 && pos <= p1) {
                shouldRemove = false;
                return true;
            }

            boolean imported = false;
            DataFlavor importFlavor = getImportFlavor(t.getTransferDataFlavors(), c);
            if (importFlavor != null) {
                try {
                    boolean useRead = false;
                    if (comp instanceof JEditorPane) {
                        JEditorPane ep = (JEditorPane)comp;
                        if (!ep.getContentType().startsWith("text/plain") &&
                                importFlavor.getMimeType().startsWith(ep.getContentType())) {
                            useRead = true;
                        }
                    }
                    InputContext ic = c.getInputContext();
                    if (ic != null) {
                        ic.endComposition();
                    }
                    Reader r = importFlavor.getReaderForText(t);

                    if (modeBetween) {
                        Caret caret = c.getCaret();
                        if (caret instanceof DefaultCaret) {
                            ((DefaultCaret)caret).setDot(pos, dropBias);
                        } else {
                            c.setCaretPosition(pos);
                        }
                    }

                    handleReaderImport(r, c, useRead);

                    if (isDrop) {
                        c.requestFocus();
                        Caret caret = c.getCaret();
                        if (caret instanceof DefaultCaret) {
                            int newPos = caret.getDot();
                            Position.Bias newBias = ((DefaultCaret)caret).getDotBias();

                            ((DefaultCaret)caret).setDot(pos, dropBias);
                            ((DefaultCaret)caret).moveDot(newPos, newBias);
                        } else {
                            c.select(pos, c.getCaretPosition());
                        }
                    }

                    imported = true;
                } catch (UnsupportedFlavorException ufe) {
                } catch (BadLocationException ble) {
                } catch (IOException ioe) {
                }
            }
            return imported;
        }

        
This method indicates if a component would accept an import of the given
set of data flavors prior to actually attempting to import it.
Params:
comp –  The component to receive the transfer.  This
 argument is provided to enable sharing of TransferHandlers by
 multiple components.
flavors –  The data formats available
Returns:
 true if the data can be inserted into the component, false otherwise./**
         * This method indicates if a component would accept an import of the given
         * set of data flavors prior to actually attempting to import it.
         *
         * @param comp  The component to receive the transfer.  This
         *  argument is provided to enable sharing of TransferHandlers by
         *  multiple components.
         * @param flavors  The data formats available
         * @return  true if the data can be inserted into the component, false otherwise.
         */
        public boolean canImport(JComponent comp, DataFlavor[] flavors) {
            JTextComponent c = (JTextComponent)comp;
            if (!(c.isEditable() && c.isEnabled())) {
                return false;
            }
            return (getImportFlavor(flavors, c) != null);
        }

        
A possible implementation of the Transferable interface
for text components.  For a JEditorPane with a rich set
of EditorKit implementations, conversions could be made
giving a wider set of formats.  This is implemented to
offer up only the active content type and text/plain
(if that is not the active format) since that can be
extracted from other formats.
/**
         * A possible implementation of the Transferable interface
         * for text components.  For a JEditorPane with a rich set
         * of EditorKit implementations, conversions could be made
         * giving a wider set of formats.  This is implemented to
         * offer up only the active content type and text/plain
         * (if that is not the active format) since that can be
         * extracted from other formats.
         */
        static class TextTransferable extends BasicTransferable {

            TextTransferable(JTextComponent c, int start, int end) {
                super(null, null);

                this.c = c;

                Document doc = c.getDocument();

                try {
                    p0 = doc.createPosition(start);
                    p1 = doc.createPosition(end);

                    plainData = c.getSelectedText();

                    if (c instanceof JEditorPane) {
                        JEditorPane ep = (JEditorPane)c;

                        mimeType = ep.getContentType();

                        if (mimeType.startsWith("text/plain")) {
                            return;
                        }

                        StringWriter sw = new StringWriter(p1.getOffset() - p0.getOffset());
                        ep.getEditorKit().write(sw, doc, p0.getOffset(), p1.getOffset() - p0.getOffset());

                        if (mimeType.startsWith("text/html")) {
                            htmlData = sw.toString();
                        } else {
                            richText = sw.toString();
                        }
                    }
                } catch (BadLocationException ble) {
                } catch (IOException ioe) {
                }
            }

            void removeText() {
                if ((p0 != null) && (p1 != null) && (p0.getOffset() != p1.getOffset())) {
                    try {
                        Document doc = c.getDocument();
                        doc.remove(p0.getOffset(), p1.getOffset() - p0.getOffset());
                    } catch (BadLocationException e) {
                    }
                }
            }

            // ---- EditorKit other than plain or HTML text -----------------------

            
If the EditorKit is not for text/plain or text/html, that format
is supported through the "richer flavors" part of BasicTransferable.
/**
             * If the EditorKit is not for text/plain or text/html, that format
             * is supported through the "richer flavors" part of BasicTransferable.
             */
            protected DataFlavor[] getRicherFlavors() {
                if (richText == null) {
                    return null;
                }

                try {
                    DataFlavor[] flavors = new DataFlavor[3];
                    flavors[0] = new DataFlavor(mimeType + ";class=java.lang.String");
                    flavors[1] = new DataFlavor(mimeType + ";class=java.io.Reader");
                    flavors[2] = new DataFlavor(mimeType + ";class=java.io.InputStream;charset=unicode");
                    return flavors;
                } catch (ClassNotFoundException cle) {
                    // fall through to unsupported (should not happen)
                }

                return null;
            }

            
The only richer format supported is the file list flavor
/**
             * The only richer format supported is the file list flavor
             */
            @SuppressWarnings("deprecation")
            protected Object getRicherData(DataFlavor flavor) throws UnsupportedFlavorException {
                if (richText == null) {
                    return null;
                }

                if (String.class.equals(flavor.getRepresentationClass())) {
                    return richText;
                } else if (Reader.class.equals(flavor.getRepresentationClass())) {
                    return new StringReader(richText);
                } else if (InputStream.class.equals(flavor.getRepresentationClass())) {
                    return new StringBufferInputStream(richText);
                }
                throw new UnsupportedFlavorException(flavor);
            }

            Position p0;
            Position p1;
            String mimeType;
            String richText;
            JTextComponent c;
        }

    }

}