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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 JComponent 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.  Client programs should not invoke methods
on this class directly.
See Also:
JComponent
UIManager/**
 * 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.)
/**
     * 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 ComponentUI 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:

Install default property values for color, fonts, borders,
    icons, opacity, etc. on the component.  Whenever possible,
    property values initialized by the client program should not
    be overridden.
Install a LayoutManager on the component if necessary.
Create/add any required sub-components to the component.
Create/install event listeners on the component.
Create/install a PropertyChangeListener on the component in order
    to detect and respond to component property changes appropriately.
Install keyboard UI (mnemonics, traversal, etc.) on the component.
Initialize any appropriate instance data.

Params:
c – the component where this UI delegate is being installed
See Also:
uninstallUI
JComponent.setUI
JComponent.updateUI/**
     * 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
installUI.  This method is invoked when this
UIComponent instance is being removed as the UI delegate
for the specified component.  This method should undo the
configuration performed in installUI, being careful to
leave the JComponent instance in a clean state (no
extraneous listeners, look-and-feel-specific property objects, etc.).
This should include the following:

Remove any UI-set borders from the component.
Remove any UI-set layout managers on the component.
Remove any UI-added sub-components from the component.
Remove any UI-added event/property listeners from the component.
Remove any UI-installed keyboard UI from the component.
Nullify any allocated instance data objects to allow for GC.

Params:
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 Also:
installUI
JComponent.updateUI/**
     * 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 ComponentUI.update method when
the specified component is being painted.  Subclasses should override
this method and use the specified Graphics object to
render the content of the component.
Params:
g – the Graphics context in which to paint
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 Also:
update/**
     * 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 JComponent
when the specified component is being painted.
By default this method fills the specified component with its background color if its opaque property is true, and then immediately calls paint. In general this method need not be overridden by subclasses; all look-and-feel rendering code should reside in the paint method. 
Params:
g – the Graphics context in which to paint
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 Also:
paint
JComponent.paintComponent/**
     * 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 null 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 null.
Params:
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 Also:
JComponent.getPreferredSize
LayoutManager.preferredLayoutSize
Returns:
a Dimension object containing given component's preferred size appropriate for the look and feel/**
     * 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
     * @return a {@code Dimension} object containing given component's preferred
     *         size appropriate for the look and feel
     * @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 null 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 getPreferredSize and returns that value.
Params:
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
See Also:
JComponent.getMinimumSize
LayoutManager.minimumLayoutSize
getPreferredSize
Returns:
a Dimension object or 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 null 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 getPreferredSize and returns that value.
Params:
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
See Also:
JComponent.getMaximumSize
LayoutManager2.maximumLayoutSize
Returns:
a Dimension object or null/**
     * 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 true if the specified x,y location is
contained within the look and feel's defined shape of the specified
component. x and y are defined to be relative
to the coordinate system of the specified component.  Although
a component's bounds 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.
Params:
c – the component where the x,y location is being queried;
         this argument is often ignored,
         but might be used if the UI object is stateless
         and shared by multiple components
x – the x coordinate of the point
y – the y coordinate of the point
See Also:
Component.contains
Component.contains
Returns:
true if the specified x,y location is contained within the look and feel's defined shape for the given component/**
     * 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
     * @return {@code true} if the specified {@code x,y} location is contained
     *         within the look and feel's defined shape for the given component
     * @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 createUI
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.
Params:
c – a JComponent for which to create a UI delegate
Returns:
a ComponentUI object for c/**
     * 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.
     *
     * @param c a {@code JComponent} for which to create a UI delegate
     * @return a {@code ComponentUI} object for {@code c}
     */
    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
LayoutManagers to align components along their
baseline.  A return value less than 0 indicates this component
does not have a reasonable baseline and that
LayoutManagers should not align this component on
its baseline.

This method returns -1.  Subclasses that have a meaningful baseline
should override appropriately.
Params:
c – JComponent baseline is being requested for
width – the width to get the baseline for
height – the height to get the baseline for
Throws:
NullPointerException – if c is null
IllegalArgumentException – if width or height is < 0
See Also:
JComponent.getBaseline(int, int)
Returns:
baseline or a value < 0 indicating there is no reasonable
                 baseline
Since:
1.6/**
     * 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 &lt; 0
     * @return baseline or a value &lt; 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.

This method returns BaselineResizeBehavior.OTHER.
Subclasses that support a baseline should override appropriately.
Params:
c – JComponent to return baseline resize behavior for
Throws:
NullPointerException – if c is null
See Also:
JComponent.getBaseline(int, int)
Returns:
an enum indicating how the baseline changes as the component
        size changes
Since:
1.6/**
     * 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 Accessible,
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
Component.AccessibleAWTComponent.getAccessibleChildrenCount() instead
of this method.
Params:
c – JComponent for which to get count of accessible children
See Also:
getAccessibleChild
Returns:
the number of accessible children in the object/**
     * 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.
     *
     * @param c {@code JComponent} for which to get count of accessible children
     * @return the number of accessible children in the object
     * @see #getAccessibleChild
     */
    public int getAccessibleChildrenCount(JComponent c) {
        return SwingUtilities.getAccessibleChildrenCount(c);
    }

    
Returns the ith Accessible 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.

Note: As of v1.3, it is recommended that developers call
Component.AccessibleAWTComponent.getAccessibleChild() instead of
this method.
Params:
c – a JComponent for which to get a child object
i – zero-based index of child
See Also:
getAccessibleChildrenCount
Returns:
the ith Accessible child of the object/**
     * 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.
     *
     * @param c a {@code JComponent} for which to get a child object
     * @param i zero-based index of child
     * @return the <code>i</code>th <code>Accessible</code> child of the object
     * @see #getAccessibleChildrenCount
     */
    public Accessible getAccessibleChild(JComponent c, int i) {
        return SwingUtilities.getAccessibleChild(c, i);
    }
}