/*

 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.

 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

 */

package javax.swing.plaf;

import javax.accessibility.Accessible;

import javax.swing.*;

import javax.swing.plaf.ComponentUI;

import java.awt.*;

import java.awt.event.*;

import java.beans.PropertyChangeEvent;

import java.beans.PropertyChangeSupport;

import java.beans.PropertyChangeListener;

import java.io.Serializable;

/**

 * The base class for all {@link javax.swing.JLayer}'s UI delegates.

 * <p/>

 * {@link #paint(java.awt.Graphics, javax.swing.JComponent)} method performes the

 * painting of the {@code JLayer}

 * and {@link #eventDispatched(AWTEvent, JLayer)} method is notified

 * about any {@code AWTEvent}s which have been generated by a {@code JLayer}

 * or any of its subcomponents.

 * <p/>

 * The {@code LayerUI} differs from the UI delegates of the other components,

 * because it is LookAndFeel independent and is not updated by default when

 * the system LookAndFeel is changed.

 * <p/>

 * The subclasses of {@code LayerUI} can either be stateless and shareable

 * by multiple {@code JLayer}s or not shareable.

 *

 * @param <V> one of the super types of {@code JLayer}'s view component

 *

 * @see JLayer#setUI(LayerUI)

 * @see JLayer#setView(Component)

 * @see JLayer#getView()

 * @since 1.7

 *

 * @author Alexander Potochkin

 */

public class LayerUI<V extends Component>

        extends ComponentUI implements Serializable {

    private final PropertyChangeSupport propertyChangeSupport =

            new PropertyChangeSupport(this);

    /**

     * Paints the specified component.

     * Subclasses should override this method and use

     * the specified {@code Graphics} object to

     * render the content of the component.

     *

     * @param g the {@code Graphics} context in which to paint;

     * @param c the component being painted;

     * it can be safely cast to the {@code JLayer<V>}

     */

    @Override

    public void paint(Graphics g, JComponent c) {

        c.paint(g);

    }

    /**

     * Dispatches {@code AWTEvent}s for {@code JLayer}

     * and <b>all it subcomponents</b> to this {@code LayerUI} instance.

     * <p>

     * To enable the {@code AWTEvent} of the particular type,

     * you call {@link javax.swing.JLayer#setLayerEventMask}

     * in {@link #installUI(javax.swing.JComponent)}

     * and set the layer event mask to {@code 0}

     * in {@link #uninstallUI(javax.swing.JComponent)} after that

     *

     * @param e the event to be dispatched

     * @param l the layer this LayerUI is set to

     *

     * @see JLayer#setLayerEventMask(long)

     * @see javax.swing.JLayer#getLayerEventMask()

     */

    public void eventDispatched(AWTEvent e, JLayer<? extends V> l){

    }

    /**

     * Invoked when {@link javax.swing.JLayer#updateUI()} is called

     * by the {@code JLayer} this {@code LayerUI} is set to.

     *

     * @param l the {@code JLayer} which UI is updated

     */

    public void updateUI(JLayer<? extends V> l){

    }

    /**

     * Configures the {@code JLayer} this {@code LayerUI} is set to.

     * The default implementation registers the {@code LayerUI}

     * as a property change listener for the passed {@code JLayer} component.

     *

     * @param c the {@code JLayer} component where this UI delegate is being installed

     */

    public void installUI(JComponent c) {

        addPropertyChangeListener((JLayer) c);

    }

    /**

     * Reverses the configuration which was previously set

     * in the {@link #installUI(JComponent)} method.

     * The default implementation unregisters the property change listener

     * for the passed JLayer component.

     *

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

     */

    public void uninstallUI(JComponent c) {

        removePropertyChangeListener((JLayer) c);

    }

    /**

     * Adds a PropertyChangeListener to the listener list. The listener is

     * registered for all bound properties of this class.

     * <p/>

     * If {@code listener} is {@code null},

     * no exception is thrown and no action is performed.

     *

     * @param listener the property change listener to be added

     * @see #removePropertyChangeListener

     * @see #getPropertyChangeListeners

     * @see #addPropertyChangeListener(String, java.beans.PropertyChangeListener)

     */

    public void addPropertyChangeListener(PropertyChangeListener listener) {

        propertyChangeSupport.addPropertyChangeListener(listener);

    }

    /**

     * Removes a PropertyChangeListener from the listener list. This method

     * should be used to remove PropertyChangeListeners that were registered

     * for all bound properties of this class.

     * <p/>

     * If {@code listener} is {@code null},

     * no exception is thrown and no action is performed.

     *

     * @param listener the PropertyChangeListener to be removed

     * @see #addPropertyChangeListener

     * @see #getPropertyChangeListeners

     * @see #removePropertyChangeListener(String, PropertyChangeListener)

     */

    public void removePropertyChangeListener(PropertyChangeListener listener) {

        propertyChangeSupport.removePropertyChangeListener(listener);

    }

    /**

     * Returns an array of all the property change listeners

     * registered on this component.

     *

     * @return all of this ui's {@code PropertyChangeListener}s

     *         or an empty array if no property change

     *         listeners are currently registered

     * @see #addPropertyChangeListener

     * @see #removePropertyChangeListener

     * @see #getPropertyChangeListeners(String)

     */

    public PropertyChangeListener[] getPropertyChangeListeners() {

        return propertyChangeSupport.getPropertyChangeListeners();

    }

    /**

     * Adds a PropertyChangeListener to the listener list for a specific

     * property.

     * <p/>

     * If {@code propertyName} or {@code listener} is {@code null},

     * no exception is thrown and no action is taken.

     *

     * @param propertyName one of the property names listed above

     * @param listener     the property change listener to be added

     * @see #removePropertyChangeListener(String, PropertyChangeListener)

     * @see #getPropertyChangeListeners(String)

     * @see #addPropertyChangeListener(String, PropertyChangeListener)

     */

    public void addPropertyChangeListener(String propertyName,

                                          PropertyChangeListener listener) {

        propertyChangeSupport.addPropertyChangeListener(propertyName, listener);

    }

    /**

     * Removes a {@code PropertyChangeListener} from the listener

     * list for a specific property. This method should be used to remove

     * {@code PropertyChangeListener}s

     * that were registered for a specific bound property.

     * <p/>

     * If {@code propertyName} or {@code listener} is {@code null},

     * no exception is thrown and no action is taken.

     *

     * @param propertyName a valid property name

     * @param listener     the PropertyChangeListener to be removed

     * @see #addPropertyChangeListener(String, PropertyChangeListener)

     * @see #getPropertyChangeListeners(String)

     * @see #removePropertyChangeListener(PropertyChangeListener)

     */

    public void removePropertyChangeListener(String propertyName,

                                             PropertyChangeListener listener) {

        propertyChangeSupport.removePropertyChangeListener(propertyName, listener);

    }

    /**

     * Returns an array of all the listeners which have been associated

     * with the named property.

     *

     * @return all of the {@code PropertyChangeListener}s associated with

     *         the named property; if no such listeners have been added or

     *         if {@code propertyName} is {@code null}, an empty

     *         array is returned

     * @see #addPropertyChangeListener(String, PropertyChangeListener)

     * @see #removePropertyChangeListener(String, PropertyChangeListener)

     * @see #getPropertyChangeListeners

     */

    public PropertyChangeListener[] getPropertyChangeListeners(String propertyName) {

        return propertyChangeSupport.getPropertyChangeListeners(propertyName);

    }

    /**

     * Support for reporting bound property changes for Object properties.

     * This method can be called when a bound property has changed and it will

     * send the appropriate PropertyChangeEvent to any registered

     * PropertyChangeListeners.

     *

     * @param propertyName the property whose value has changed

     * @param oldValue     the property's previous value

     * @param newValue     the property's new value

     */

    protected void firePropertyChange(String propertyName,

                                      Object oldValue, Object newValue) {

        propertyChangeSupport.firePropertyChange(propertyName, oldValue, newValue);

    }

    /**

     * Notifies the {@code LayerUI} when any of its property are changed

     * and enables updating every {@code JLayer} this {@code LayerUI} instance is set to.

     *

     * @param evt the PropertyChangeEvent generated by this {@code LayerUI}

     * @param l the {@code JLayer} this LayerUI is set to

     */

    public void applyPropertyChange(PropertyChangeEvent evt, JLayer<? extends V> l) {

    }

    /**

     * Returns the preferred size of the viewport for a view component.

     *

     * @return the preferred size of the viewport for a view component

     * @see Scrollable#getPreferredScrollableViewportSize()

     */

    public Dimension getPreferredScrollableViewportSize(JLayer<? extends V> l) {

        if (l.getView() instanceof Scrollable) {

            return ((Scrollable)l.getView()).getPreferredScrollableViewportSize();

        }

        return l.getPreferredSize();

    }

    /**

     * Returns a scroll increment, which is required for components

     * that display logical rows or columns in order to completely expose

     * one block of rows or columns, depending on the value of orientation.

     *

     * @return the "block" increment for scrolling in the specified direction

     * @see Scrollable#getScrollableBlockIncrement(Rectangle, int, int)

     */

     public int getScrollableBlockIncrement(JLayer<? extends V> l,

                                           Rectangle visibleRect,

                                           int orientation, int direction) {

        if (l.getView() instanceof Scrollable) {

            return ((Scrollable)l.getView()).getScrollableBlockIncrement(

                    visibleRect,orientation, direction);

        }

        return (orientation == SwingConstants.VERTICAL) ? visibleRect.height :

            visibleRect.width;

    }

    /**

     * Returns {@code false} to indicate that the height of the viewport does not

     * determine the height of the layer, unless the preferred height

     * of the layer is smaller than the height of the viewport.

     *

     * @return whether the layer should track the height of the viewport

     * @see Scrollable#getScrollableTracksViewportHeight()

     */

    public boolean getScrollableTracksViewportHeight(JLayer<? extends V> l) {

        if (l.getView() instanceof Scrollable) {

            return ((Scrollable)l.getView()).getScrollableTracksViewportHeight();

        }

        if (l.getParent() instanceof JViewport) {

            return (((JViewport)l.getParent()).getHeight() > l.getPreferredSize().height);

        }

        return false;

    }

    /**

     * Returns {@code false} to indicate that the width of the viewport does not

     * determine the width of the layer, unless the preferred width

     * of the layer is smaller than the width of the viewport.

     *

     * @return whether the layer should track the width of the viewport

     * @see Scrollable

     * @see LayerUI#getScrollableTracksViewportWidth(JLayer)

     */

    public boolean getScrollableTracksViewportWidth(JLayer<? extends V> l) {

        if (l.getView() instanceof Scrollable) {

            return ((Scrollable)l.getView()).getScrollableTracksViewportWidth();

        }

        if (l.getParent() instanceof JViewport) {

            return (((JViewport)l.getParent()).getWidth() > l.getPreferredSize().width);

        }

        return false;

    }

    /**

     * Returns a scroll increment, which is required for components

     * that display logical rows or columns in order to completely expose

     * one new row or column, depending on the value of orientation.

     * Ideally, components should handle a partially exposed row or column

     * by returning the distance required to completely expose the item.

     * <p>

     * Scrolling containers, like JScrollPane, will use this method

     * each time the user requests a unit scroll.

     *

     * @return The "unit" increment for scrolling in the specified direction.

     *         This value should always be positive.

     * @see Scrollable#getScrollableUnitIncrement(Rectangle, int, int)

     */

    public int getScrollableUnitIncrement(JLayer<? extends V> l,

                                          Rectangle visibleRect,

                                          int orientation, int direction) {

        if (l.getView() instanceof Scrollable) {

            return ((Scrollable)l.getView()).getScrollableUnitIncrement(

                    visibleRect, orientation, direction);

        }

        return 1;

    }

    /**

     * If the {@code JLayer}'s view component is not {@code null},

     * this calls the view's {@code getBaseline()} method.

     * Otherwise, the default implementation is called.

     *

     * @param c {@code JLayer} to return baseline resize behavior for

     * @param width the width to get the baseline for

     * @param height the height to get the baseline for

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

     *                  baseline

     */

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

        JLayer l = (JLayer) c;

        if (l.getView() != null) {

            return l.getView().getBaseline(width, height);

        }

        return super.getBaseline(c, width, height);

     }

    /**

     * If the {@code JLayer}'s view component is not {@code null},

     * this calls the view's {@code getBaselineResizeBehavior()} method.

     * Otherwise, the default implementation is called.

     *

     * @param c {@code JLayer} to return baseline resize behavior for

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

     *         size changes

     */

    public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c) {

        JLayer l = (JLayer) c;

        if (l.getView() != null) {

            return l.getView().getBaselineResizeBehavior();

        }

        return super.getBaselineResizeBehavior(c);

    }

}