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 * 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.plaf;

import javax.swing.JComponent;

import javax.swing.SwingUtilities;

import javax.accessibility.Accessible;

import java.awt.Component;

import java.awt.Container;

import java.awt.Dimension;

import java.awt.Graphics;

import java.awt.Insets;

/**

 * The base class for all UI delegate objects in the Swing pluggable

 * look and feel architecture.  The UI delegate object for a Swing

 * component is responsible for implementing the aspects of the

 * component that depend on the look and feel.

 * The <code>JComponent</code> class

 * invokes methods from this class in order to delegate operations

 * (painting, layout calculations, etc.) that may vary depending on the

 * look and feel installed.  <b>Client programs should not invoke methods

 * on this class directly.</b>

 *

 * @see javax.swing.JComponent

 * @see javax.swing.UIManager

 *

 */

public abstract class ComponentUI {

    /**

     * Sole constructor. (For invocation by subclass constructors,

     * typically implicit.)

     */

    public ComponentUI() {

    }

    /**

     * Configures the specified component appropriately for the look and feel.

     * This method is invoked when the <code>ComponentUI</code> instance is being installed

     * as the UI delegate on the specified component.  This method should

     * completely configure the component for the look and feel,

     * including the following:

     * <ol>

     * <li>Install default property values for color, fonts, borders,

     *     icons, opacity, etc. on the component.  Whenever possible,

     *     property values initialized by the client program should <i>not</i>

     *     be overridden.

     * <li>Install a <code>LayoutManager</code> on the component if necessary.

     * <li>Create/add any required sub-components to the component.

     * <li>Create/install event listeners on the component.

     * <li>Create/install a <code>PropertyChangeListener</code> on the component in order

     *     to detect and respond to component property changes appropriately.

     * <li>Install keyboard UI (mnemonics, traversal, etc.) on the component.

     * <li>Initialize any appropriate instance data.

     * </ol>

     * @param c the component where this UI delegate is being installed

     *

     * @see #uninstallUI

     * @see javax.swing.JComponent#setUI

     * @see javax.swing.JComponent#updateUI

     */

    public void installUI(JComponent c) {

    }

    /**

     * Reverses configuration which was done on the specified component during

     * <code>installUI</code>.  This method is invoked when this

     * <code>UIComponent</code> instance is being removed as the UI delegate

     * for the specified component.  This method should undo the

     * configuration performed in <code>installUI</code>, being careful to

     * leave the <code>JComponent</code> instance in a clean state (no

     * extraneous listeners, look-and-feel-specific property objects, etc.).

     * This should include the following:

     * <ol>

     * <li>Remove any UI-set borders from the component.

     * <li>Remove any UI-set layout managers on the component.

     * <li>Remove any UI-added sub-components from the component.

     * <li>Remove any UI-added event/property listeners from the component.

     * <li>Remove any UI-installed keyboard UI from the component.

     * <li>Nullify any allocated instance data objects to allow for GC.

     * </ol>

     * @param c the component from which this UI delegate is being removed;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     *

     * @see #installUI

     * @see javax.swing.JComponent#updateUI

     */

    public void uninstallUI(JComponent c) {

    }

    /**

     * Paints the specified component appropriately for the look and feel.

     * This method is invoked from the <code>ComponentUI.update</code> method when

     * the specified component is being painted.  Subclasses should override

     * this method and use the specified <code>Graphics</code> object to

     * render the content of the component.

     *

     * @param g the <code>Graphics</code> context in which to paint

     * @param c the component being painted;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     *

     * @see #update

     */

    public void paint(Graphics g, JComponent c) {

    }

    /**

     * Notifies this UI delegate that it is time to paint the specified

     * component.  This method is invoked by <code>JComponent</code>

     * when the specified component is being painted.

     *

     * <p>By default this method fills the specified component with

     * its background color if its {@code opaque} property is {@code true},

     * and then immediately calls {@code paint}. In general this method need

     * not be overridden by subclasses; all look-and-feel rendering code should

     * reside in the {@code paint} method.

     *

     * @param g the <code>Graphics</code> context in which to paint

     * @param c the component being painted;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     *

     * @see #paint

     * @see javax.swing.JComponent#paintComponent

     */

    public void update(Graphics g, JComponent c) {

        if (c.isOpaque()) {

            g.setColor(c.getBackground());

            g.fillRect(0, 0, c.getWidth(),c.getHeight());

        }

        paint(g, c);

    }

    /**

     * Returns the specified component's preferred size appropriate for

     * the look and feel.  If <code>null</code> is returned, the preferred

     * size will be calculated by the component's layout manager instead

     * (this is the preferred approach for any component with a specific

     * layout manager installed).  The default implementation of this

     * method returns <code>null</code>.

     *

     * @param c the component whose preferred size is being queried;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     *

     * @see javax.swing.JComponent#getPreferredSize

     * @see java.awt.LayoutManager#preferredLayoutSize

     */

    public Dimension getPreferredSize(JComponent c) {

        return null;

    }

    /**

     * Returns the specified component's minimum size appropriate for

     * the look and feel.  If <code>null</code> is returned, the minimum

     * size will be calculated by the component's layout manager instead

     * (this is the preferred approach for any component with a specific

     * layout manager installed).  The default implementation of this

     * method invokes <code>getPreferredSize</code> and returns that value.

     *

     * @param c the component whose minimum size is being queried;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     *

     * @return a <code>Dimension</code> object or <code>null</code>

     *

     * @see javax.swing.JComponent#getMinimumSize

     * @see java.awt.LayoutManager#minimumLayoutSize

     * @see #getPreferredSize

     */

    public Dimension getMinimumSize(JComponent c) {

        return getPreferredSize(c);

    }

    /**

     * Returns the specified component's maximum size appropriate for

     * the look and feel.  If <code>null</code> is returned, the maximum

     * size will be calculated by the component's layout manager instead

     * (this is the preferred approach for any component with a specific

     * layout manager installed).  The default implementation of this

     * method invokes <code>getPreferredSize</code> and returns that value.

     *

     * @param c the component whose maximum size is being queried;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     * @return a <code>Dimension</code> object or <code>null</code>

     *

     * @see javax.swing.JComponent#getMaximumSize

     * @see java.awt.LayoutManager2#maximumLayoutSize

     */

    public Dimension getMaximumSize(JComponent c) {

        return getPreferredSize(c);

    }

    /**

     * Returns <code>true</code> if the specified <i>x,y</i> location is

     * contained within the look and feel's defined shape of the specified

     * component. <code>x</code> and <code>y</code> are defined to be relative

     * to the coordinate system of the specified component.  Although

     * a component's <code>bounds</code> is constrained to a rectangle,

     * this method provides the means for defining a non-rectangular

     * shape within those bounds for the purpose of hit detection.

     *

     * @param c the component where the <i>x,y</i> location is being queried;

     *          this argument is often ignored,

     *          but might be used if the UI object is stateless

     *          and shared by multiple components

     * @param x the <i>x</i> coordinate of the point

     * @param y the <i>y</i> coordinate of the point

     *

     * @see javax.swing.JComponent#contains

     * @see java.awt.Component#contains

     */

    @SuppressWarnings("deprecation")

    public boolean contains(JComponent c, int x, int y) {

        return c.inside(x, y);

    }

    /**

     * Returns an instance of the UI delegate for the specified component.

     * Each subclass must provide its own static <code>createUI</code>

     * method that returns an instance of that UI delegate subclass.

     * If the UI delegate subclass is stateless, it may return an instance

     * that is shared by multiple components.  If the UI delegate is

     * stateful, then it should return a new instance per component.

     * The default implementation of this method throws an error, as it

     * should never be invoked.

     */

    public static ComponentUI createUI(JComponent c) {

        throw new Error("ComponentUI.createUI not implemented.");

    }

    /**

     * Returns the baseline.  The baseline is measured from the top of

     * the component.  This method is primarily meant for

     * <code>LayoutManager</code>s to align components along their

     * baseline.  A return value less than 0 indicates this component

     * does not have a reasonable baseline and that

     * <code>LayoutManager</code>s should not align this component on

     * its baseline.

     * <p>

     * This method returns -1.  Subclasses that have a meaningful baseline

     * should override appropriately.

     *

     * @param c <code>JComponent</code> baseline is being requested for

     * @param width the width to get the baseline for

     * @param height the height to get the baseline for

     * @throws NullPointerException if <code>c</code> is <code>null</code>

     * @throws IllegalArgumentException if width or height is < 0

     * @return baseline or a value < 0 indicating there is no reasonable

     *                  baseline

     * @see javax.swing.JComponent#getBaseline(int,int)

     * @since 1.6

     */

    public int getBaseline(JComponent c, int width, int height) {

        if (c == null) {

            throw new NullPointerException("Component must be non-null");

        }

        if (width < 0 || height < 0) {

            throw new IllegalArgumentException(

                    "Width and height must be >= 0");

        }

        return -1;

    }

    /**

     * Returns an enum indicating how the baseline of the component

     * changes as the size changes.  This method is primarily meant for

     * layout managers and GUI builders.

     * <p>

     * This method returns <code>BaselineResizeBehavior.OTHER</code>.

     * Subclasses that support a baseline should override appropriately.

     *

     * @param c <code>JComponent</code> to return baseline resize behavior for

     * @return an enum indicating how the baseline changes as the component

     *         size changes

     * @throws NullPointerException if <code>c</code> is <code>null</code>

     * @see javax.swing.JComponent#getBaseline(int, int)

     * @since 1.6

     */

    public Component.BaselineResizeBehavior getBaselineResizeBehavior(

            JComponent c) {

        if (c == null) {

            throw new NullPointerException("Component must be non-null");

        }

        return Component.BaselineResizeBehavior.OTHER;

    }

    /**

     * Returns the number of accessible children in the object.  If all

     * of the children of this object implement <code>Accessible</code>,

     * this

     * method should return the number of children of this object.

     * UIs might wish to override this if they present areas on the

     * screen that can be viewed as components, but actual components

     * are not used for presenting those areas.

     *

     * Note: As of v1.3, it is recommended that developers call

     * <code>Component.AccessibleAWTComponent.getAccessibleChildrenCount()</code> instead

     * of this method.

     *

     * @see #getAccessibleChild

     * @return the number of accessible children in the object

     */

    public int getAccessibleChildrenCount(JComponent c) {

        return SwingUtilities.getAccessibleChildrenCount(c);

    }

    /**

     * Returns the <code>i</code>th <code>Accessible</code> child of the object.

     * UIs might need to override this if they present areas on the

     * screen that can be viewed as components, but actual components

     * are not used for presenting those areas.

     *

     * <p>

     *

     * Note: As of v1.3, it is recommended that developers call

     * <code>Component.AccessibleAWTComponent.getAccessibleChild()</code> instead of

     * this method.

     *

     * @see #getAccessibleChildrenCount

     * @param i zero-based index of child

     * @return the <code>i</code>th <code>Accessible</code> child of the object

     */

    public Accessible getAccessibleChild(JComponent c, int i) {

        return SwingUtilities.getAccessibleChild(c, i);

    }

}