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 * Copyright (c) 1997, 2011, 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,

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 *

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package javax.swing;

import java.awt.Font;

import java.awt.event.InputEvent;

import java.awt.event.KeyEvent;

import java.awt.Color;

import java.awt.Component;

import java.awt.SystemColor;

import java.awt.Toolkit;

import sun.awt.SunToolkit;

import javax.swing.text.*;

import javax.swing.border.*;

import javax.swing.plaf.*;

import java.net.URL;

import sun.swing.SwingUtilities2;

import sun.swing.DefaultLayoutStyle;

import sun.swing.ImageIconUIResource;

import java.util.StringTokenizer;

/**

 * {@code LookAndFeel}, as the name implies, encapsulates a look and

 * feel. Beyond installing a look and feel most developers never need to

 * interact directly with {@code LookAndFeel}. In general only developers

 * creating a custom look and feel need to concern themselves with this class.

 * <p>

 * Swing is built upon the foundation that each {@code JComponent}

 * subclass has an implementation of a specific {@code ComponentUI}

 * subclass. The {@code ComponentUI} is often referred to as "the ui",

 * "component ui", or "look and feel delegate". The {@code ComponentUI}

 * subclass is responsible for providing the look and feel specific

 * functionality of the component. For example, {@code JTree} requires

 * an implementation of the {@code ComponentUI} subclass {@code

 * TreeUI}. The implementation of the specific {@code

 * ComponentUI} subclass is provided by the {@code LookAndFeel}. Each

 * {@code JComponent} subclass identifies the {@code ComponentUI}

 * subclass it requires by way of the {@code JComponent} method {@code

 * getUIClassID}.

 * <p>

 * Each {@code LookAndFeel} implementation must provide

 * an implementation of the appropriate {@code ComponentUI} subclass by

 * specifying a value for each of Swing's ui class ids in the {@code

 * UIDefaults} object returned from {@code getDefaults}. For example,

 * {@code BasicLookAndFeel} uses {@code BasicTreeUI} as the concrete

 * implementation for {@code TreeUI}. This is accomplished by {@code

 * BasicLookAndFeel} providing the key-value pair {@code

 * "TreeUI"-"javax.swing.plaf.basic.BasicTreeUI"}, in the

 * {@code UIDefaults} returned from {@code getDefaults}. Refer to

 * {@link UIDefaults#getUI(JComponent)} for defails on how the implementation

 * of the {@code ComponentUI} subclass is obtained.

 * <p>

 * When a {@code LookAndFeel} is installed the {@code UIManager} does

 * not check that an entry exists for all ui class ids. As such,

 * random exceptions will occur if the current look and feel has not

 * provided a value for a particular ui class id and an instance of

 * the {@code JComponent} subclass is created.

 *

 * <h2>Recommendations for Look and Feels</h2>

 *

 * As noted in {@code UIManager} each {@code LookAndFeel} has the opportunity

 * to provide a set of defaults that are layered in with developer and

 * system defaults. Some of Swing's components require the look and feel

 * to provide a specific set of defaults. These are documented in the

 * classes that require the specific default.

 *

 * <h3><a name="#defaultRecommendation">ComponentUIs and defaults</a></h2>

 *

 * All {@code ComponentUIs} typically need to set various properties

 * on the {@code JComponent} the {@code ComponentUI} is providing the

 * look and feel for. This is typically done when the {@code

 * ComponentUI} is installed on the {@code JComponent}. Setting a

 * property should only be done if the developer has not set the

 * property. For non-primitive values it is recommended that the

 * {@code ComponentUI} only change the property on the {@code

 * JComponent} if the current value is {@code null} or implements

 * {@code UIResource}. If the current value is {@code null} or

 * implements {@code UIResource} it indicates the property has not

 * been set by the developer, and the ui is free to change it.  For

 * example, {@code BasicButtonUI.installDefaults} only changes the

 * font on the {@code JButton} if the return value from {@code

 * button.getFont()} is {@code null} or implements {@code

 * UIResource}. On the other hand if {@code button.getFont()} returned

 * a {@code non-null} value that did not implement {@code UIResource}

 * then {@code BasicButtonUI.installDefaults} would not change the

 * {@code JButton}'s font.

 * <p>

 * For primitive values, such as {@code opaque}, the method {@code

 * installProperty} should be invoked.  {@code installProperty} only changes

 * the correspoding property if the value has not been changed by the

 * developer.

 * <p>

 * {@code ComponentUI} implementations should use the various install methods

 * provided by this class as they handle the necessary checking and install

 * the property using the recommended guidelines.

 * <p>

 * <h3><a name="exceptions"></a>Exceptions</h3>

 *

 * All of the install methods provided by {@code LookAndFeel} need to

 * access the defaults if the value of the property being changed is

 * {@code null} or a {@code UIResource}. For example, installing the

 * font does the following:

 * <pre>

 *   JComponent c;

 *   Font font = c.getFont();

 *   if (font == null || (font instanceof UIResource)) {

 *       c.setFont(UIManager.getFont("fontKey"));

 *   }

 * </pre>

 * If the font is {@code null} or a {@code UIResource}, the

 * defaults table is queried with the key {@code fontKey}. All of

 * {@code UIDefault's} get methods throw a {@code

 * NullPointerException} if passed in {@code null}. As such, unless

 * otherwise noted each of the various install methods of {@code

 * LookAndFeel} throw a {@code NullPointerException} if the current

 * value is {@code null} or a {@code UIResource} and the supplied

 * defaults key is {@code null}. In addition, unless otherwise specified

 * all of the {@code install} methods throw a {@code NullPointerException} if

 * a {@code null} component is passed in.

 *

 * @author Tom Ball

 * @author Hans Muller

 */

public abstract class LookAndFeel

{

    /**

     * Convenience method for setting a component's foreground

     * and background color properties with values from the

     * defaults.  The properties are only set if the current

     * value is either {@code null} or a {@code UIResource}.

     *

     * @param c component to set the colors on

     * @param defaultBgName key for the background

     * @param defaultFgName key for the foreground

     *

     * @see #installColorsAndFont

     * @see UIManager#getColor

     * @throws NullPointerException as described in

     *         <a href="#exceptions">exceptions</a>

     */

    public static void installColors(JComponent c,

                                     String defaultBgName,

                                     String defaultFgName)

    {

        Color bg = c.getBackground();

        if (bg == null || bg instanceof UIResource) {

            c.setBackground(UIManager.getColor(defaultBgName));

        }

        Color fg = c.getForeground();

        if (fg == null || fg instanceof UIResource) {

            c.setForeground(UIManager.getColor(defaultFgName));

        }

    }

    /**

     * Convenience method for setting a component's foreground,

     * background and font properties with values from the

     * defaults.  The properties are only set if the current

     * value is either {@code null} or a {@code UIResource}.

     *

     * @param c component set to the colors and font on

     * @param defaultBgName key for the background

     * @param defaultFgName key for the foreground

     * @param defaultFontName key for the font

     * @throws NullPointerException as described in

     *         <a href="#exceptions">exceptions</a>

     *

     * @see #installColors

     * @see UIManager#getColor

     * @see UIManager#getFont

     */

    public static void installColorsAndFont(JComponent c,

                                         String defaultBgName,

                                         String defaultFgName,

                                         String defaultFontName) {

        Font f = c.getFont();

        if (f == null || f instanceof UIResource) {

            c.setFont(UIManager.getFont(defaultFontName));

        }

        installColors(c, defaultBgName, defaultFgName);

    }

    /**

     * Convenience method for setting a component's border property with

     * a value from the defaults. The border is only set if the border is

     * {@code null} or an instance of {@code UIResource}.

     *

     * @param c component to set the border on

     * @param defaultBorderName key specifying the border

     * @throws NullPointerException as described in

     *         <a href="#exceptions">exceptions</a>

     */

    public static void installBorder(JComponent c, String defaultBorderName) {

        Border b = c.getBorder();

        if (b == null || b instanceof UIResource) {

            c.setBorder(UIManager.getBorder(defaultBorderName));

        }

    }

    /**

     * Convenience method for uninstalling a border. If the border of

     * the component is a {@code UIResource}, it is set to {@code

     * null}.

     *

     * @param c component to uninstall the border on

     * @throws NullPointerException if {@code c} is {@code null}

     */

    public static void uninstallBorder(JComponent c) {

        if (c.getBorder() instanceof UIResource) {

            c.setBorder(null);

        }

    }

    /**

     * Convenience method for installing a property with the specified name

     * and value on a component if that property has not already been set

     * by the developer.  This method is intended to be used by

     * ui delegate instances that need to specify a default value for a

     * property of primitive type (boolean, int, ..), but do not wish

     * to override a value set by the client.  Since primitive property

     * values cannot be wrapped with the {@code UIResource} marker, this method

     * uses private state to determine whether the property has been set

     * by the client.

     *

     * @throws IllegalArgumentException if the specified property is not

     *         one which can be set using this method

     * @throws ClassCastException if the property value has not been set

     *         by the developer and the type does not match the property's type

     * @throws NullPointerException if {@code c} is {@code null}, or the

     *         named property has not been set by the developer and

     *         {@code propertyValue} is {@code null}

     * @param c target component to set the property on

     * @param propertyName name of the property to set

     * @param propertyValue value of the property

     * @since 1.5

     */

    public static void installProperty(JComponent c,

                                       String propertyName, Object propertyValue) {

        // this is a special case because the JPasswordField's ancestor heirarchy

        // includes a class outside of javax.swing, thus we cannot call setUIProperty

        // directly.

        if (SunToolkit.isInstanceOf(c, "javax.swing.JPasswordField")) {

            if (!((JPasswordField)c).customSetUIProperty(propertyName, propertyValue)) {

                c.setUIProperty(propertyName, propertyValue);

            }

        } else {

            c.setUIProperty(propertyName, propertyValue);

        }

    }

    /**

     * Convenience method for building an array of {@code

     * KeyBindings}. While this method is not deprecated, developers

     * should instead use {@code ActionMap} and {@code InputMap} for

     * supplying key bindings.

     * <p>

     * This method returns an array of {@code KeyBindings}, one for each

     * alternating {@code key-action} pair in {@code keyBindingList}.

     * A {@code key} can either be a {@code String} in the format

     * specified by the <code>KeyStroke.getKeyStroke</code> method, or

     * a {@code KeyStroke}. The {@code action} part of the pair is a

     * {@code String} that corresponds to the name of the {@code

     * Action}.

     * <p>

     * The following example illustrates creating a {@code KeyBinding} array

     * from six alternating {@code key-action} pairs:

     * <pre>

     *  JTextComponent.KeyBinding[] multilineBindings = makeKeyBindings( new Object[] {

     *          "UP", DefaultEditorKit.upAction,

     *        "DOWN", DefaultEditorKit.downAction,

     *     "PAGE_UP", DefaultEditorKit.pageUpAction,

     *   "PAGE_DOWN", DefaultEditorKit.pageDownAction,

     *       "ENTER", DefaultEditorKit.insertBreakAction,

     *         "TAB", DefaultEditorKit.insertTabAction

     *  });

     * </pre>

     * If {@code keyBindingList's} length is odd, the last element is

     * ignored.

     * <p>

     * Supplying a {@code null} value for either the {@code key} or

     * {@code action} part of the {@code key-action} pair results in

     * creating a {@code KeyBinding} with the corresponding value

     * {@code null}. As other parts of Swing's expect {@code non-null} values

     * in a {@code KeyBinding}, you should avoid supplying {@code null} as

     * either the {@code key} or {@code action} part of the {@code key-action}

     * pair.

     *

     * @param keyBindingList an array of {@code key-action} pairs

     * @return an array of {@code KeyBindings}

     * @throws NullPointerException if {@code keyBindingList} is {@code null}

     * @throws ClassCastException if the {@code key} part of the pair is

     *         not a {@code KeyStroke} or {@code String}, or the

     *         {@code action} part of the pair is not a {@code String}

     * @see ActionMap

     * @see InputMap

     * @see KeyStroke#getKeyStroke

     */

    public static JTextComponent.KeyBinding[] makeKeyBindings(Object[] keyBindingList)

    {

        JTextComponent.KeyBinding[] rv = new JTextComponent.KeyBinding[keyBindingList.length / 2];

        for(int i = 0; i < rv.length; i ++) {

            Object o = keyBindingList[2 * i];

            KeyStroke keystroke = (o instanceof KeyStroke)

                ? (KeyStroke) o

                : KeyStroke.getKeyStroke((String) o);

            String action = (String) keyBindingList[2 * i + 1];

            rv[i] = new JTextComponent.KeyBinding(keystroke, action);

        }

        return rv;

    }

    /**

     * Creates a {@code InputMapUIResource} from <code>keys</code>. This is

     * a convenience method for creating a new {@code InputMapUIResource},

     * invoking {@code loadKeyBindings(map, keys)}, and returning the

     * {@code InputMapUIResource}.

     *

     * @param keys alternating pairs of {@code keystroke-action key}

     *        pairs as described in {@link #loadKeyBindings}

     * @return newly created and populated {@code InputMapUIResource}

     * @see #loadKeyBindings

     *

     * @since 1.3

     */

    public static InputMap makeInputMap(Object[] keys) {

        InputMap retMap = new InputMapUIResource();

        loadKeyBindings(retMap, keys);

        return retMap;

    }

    /**

     * Creates a {@code ComponentInputMapUIResource} from

     * <code>keys</code>. This is a convenience method for creating a

     * new {@code ComponentInputMapUIResource}, invoking {@code

     * loadKeyBindings(map, keys)}, and returning the {@code

     * ComponentInputMapUIResource}.

     *

     * @param c component to create the {@code ComponentInputMapUIResource}

     *          with

     * @param keys alternating pairs of {@code keystroke-action key}

     *        pairs as described in {@link #loadKeyBindings}

     * @return newly created and populated {@code InputMapUIResource}

     * @throws IllegalArgumentException if {@code c} is {@code null}

     *

     * @see #loadKeyBindings

     * @see ComponentInputMapUIResource

     *

     * @since 1.3

     */

    public static ComponentInputMap makeComponentInputMap(JComponent c,

                                                          Object[] keys) {

        ComponentInputMap retMap = new ComponentInputMapUIResource(c);

        loadKeyBindings(retMap, keys);

        return retMap;

    }

    /**

     * Populates an {@code InputMap} with the specified bindings.

     * The bindings are supplied as a list of alternating

     * {@code keystroke-action key} pairs. The {@code keystroke} is either

     * an instance of {@code KeyStroke}, or a {@code String}

     * that identifies the {@code KeyStroke} for the binding. Refer

     * to {@code KeyStroke.getKeyStroke(String)} for the specific

     * format. The {@code action key} part of the pair is the key

     * registered in the {@code InputMap} for the {@code KeyStroke}.

     * <p>

     * The following illustrates loading an {@code InputMap} with two

     * {@code key-action} pairs:

     * <pre>

     *   LookAndFeel.loadKeyBindings(inputMap, new Object[] {

     *     "control X", "cut",

     *     "control V", "paste"

     *   });

     * </pre>

     * <p>

     * Supplying a {@code null} list of bindings ({@code keys}) does not

     * change {@code retMap} in any way.

     * <p>

     * Specifying a {@code null} {@code action key} results in

     * removing the {@code keystroke's} entry from the {@code InputMap}.

     * A {@code null} {@code keystroke} is ignored.

     *

     * @param retMap {@code InputMap} to add the {@code key-action}

     *               pairs to

     * @param keys bindings to add to {@code retMap}

     * @throws NullPointerException if {@code keys} is

     *         {@code non-null}, not empty, and {@code retMap} is

     *         {@code null}

     *

     * @see KeyStroke#getKeyStroke(String)

     * @see InputMap

     *

     * @since 1.3

     */

    public static void loadKeyBindings(InputMap retMap, Object[] keys) {

        if (keys != null) {

            for (int counter = 0, maxCounter = keys.length;

                 counter < maxCounter; counter++) {

                Object keyStrokeO = keys[counter++];

                KeyStroke ks = (keyStrokeO instanceof KeyStroke) ?

                                (KeyStroke)keyStrokeO :

                                KeyStroke.getKeyStroke((String)keyStrokeO);

                retMap.put(ks, keys[counter]);

            }

        }

    }

    /**

     * Creates and returns a {@code UIDefault.LazyValue} that loads an

     * image. The returned value is an implementation of {@code

     * UIDefaults.LazyValue}. When {@code createValue} is invoked on

     * the returned object, the image is loaded. If the image is {@code

     * non-null}, it is then wrapped in an {@code Icon} that implements {@code

     * UIResource}. The image is loaded using {@code

     * Class.getResourceAsStream(gifFile)}.

     * <p>

     * This method does not check the arguments in any way. It is

     * strongly recommended that {@code non-null} values are supplied else

     * exceptions may occur when {@code createValue} is invoked on the

     * returned object.

     *

     * @param baseClass {@code Class} used to load the resource

     * @param gifFile path to the image to load

     * @return a {@code UIDefaults.LazyValue}; when resolved the

     *         {@code LazyValue} loads the specified image

     * @see UIDefaults.LazyValue

     * @see Icon

     * @see Class#getResourceAsStream(String)

     */

    public static Object makeIcon(final Class<?> baseClass, final String gifFile) {

        return SwingUtilities2.makeIcon(baseClass, baseClass, gifFile);

    }

    /**

     * Returns the <code>LayoutStyle</code> for this look

     * and feel.  This never returns {@code null}.

     * <p>

     * You generally don't use the <code>LayoutStyle</code> from

     * the look and feel, instead use the <code>LayoutStyle</code>

     * method <code>getInstance</code>.

     *

     * @see LayoutStyle#getInstance

     * @return the <code>LayoutStyle</code> for this look and feel

     * @since 1.6

     */

    public LayoutStyle getLayoutStyle() {

        return DefaultLayoutStyle.getInstance();

    }

    /**

     * Invoked when the user attempts an invalid operation,

     * such as pasting into an uneditable <code>JTextField</code>

     * that has focus. The default implementation beeps. Subclasses

     * that wish different behavior should override this and provide

     * the additional feedback.

     *

     * @param component the <code>Component</code> the error occurred in,

     *                  may be <code>null</code>

     *                  indicating the error condition is not directly

     *                  associated with a <code>Component</code>

     * @since 1.4

     */

    public void provideErrorFeedback(Component component) {

        Toolkit toolkit = null;

        if (component != null) {

            toolkit = component.getToolkit();

        } else {

            toolkit = Toolkit.getDefaultToolkit();

        }

        toolkit.beep();

    } // provideErrorFeedback()

    /**

     * Returns the value of the specified system desktop property by

     * invoking <code>Toolkit.getDefaultToolkit().getDesktopProperty()</code>.

     * If the value of the specified property is {@code null},

     * {@code fallbackValue} is returned.

     *

     * @param systemPropertyName the name of the system desktop property being queried

     * @param fallbackValue the object to be returned as the value if the system value is null

     * @return the current value of the desktop property

     *

     * @see java.awt.Toolkit#getDesktopProperty

     *

     * @since 1.4

     */

    public static Object getDesktopPropertyValue(String systemPropertyName, Object fallbackValue) {

        Object value = Toolkit.getDefaultToolkit().getDesktopProperty(systemPropertyName);

        if (value == null) {

            return fallbackValue;

        } else if (value instanceof Color) {