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	/*
	* Copyright (c) 1997, 2013, 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package javax.swing;

	import java.util.List;
	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Iterator;
	import javax.swing.plaf.*;
	import javax.accessibility.*;

	import java.awt.Component;
	import java.awt.Container;
	import java.awt.DefaultFocusTraversalPolicy;
	import java.awt.FocusTraversalPolicy;
	import java.awt.Window;
	import java.io.ObjectOutputStream;
	import java.io.ObjectInputStream;
	import java.io.IOException;
	import java.beans.PropertyVetoException;
	import java.util.Set;
	import java.util.TreeSet;
	import java.util.LinkedHashSet;
	/**
	* A container used to create a multiple-document interface or a virtual desktop.
	* You create <code>JInternalFrame</code> objects and add them to the
	* <code>JDesktopPane</code>. <code>JDesktopPane</code> extends
	* <code>JLayeredPane</code> to manage the potentially overlapping internal
	* frames. It also maintains a reference to an instance of
	* <code>DesktopManager</code> that is set by the UI
	* class for the current look and feel (L&F). Note that <code>JDesktopPane</code>
	* does not support borders.
	* <p>
	* This class is normally used as the parent of <code>JInternalFrames</code>
	* to provide a pluggable <code>DesktopManager</code> object to the
	* <code>JInternalFrames</code>. The <code>installUI</code> of the
	* L&F specific implementation is responsible for setting the
	* <code>desktopManager</code> variable appropriately.
	* When the parent of a <code>JInternalFrame</code> is a <code>JDesktopPane</code>,
	* it should delegate most of its behavior to the <code>desktopManager</code>
	* (closing, resizing, etc).
	* <p>
	* For further documentation and examples see
	* <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/internalframe.html">How to Use Internal Frames</a>,
	* a section in <em>The Java Tutorial</em>.
	* <p>
	* <strong>Warning:</strong> Swing is not thread safe. For more
	* information see <a
	* href="package-summary.html#threading">Swing's Threading
	* Policy</a>.
	* <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}.
	*
	* @see JInternalFrame
	* @see JInternalFrame.JDesktopIcon
	* @see DesktopManager
	*
	* @author David Kloba
	*/
	public class JDesktopPane extends JLayeredPane implements Accessible
	{
	/**
	* @see #getUIClassID
	* @see #readObject
	*/
	private static final String uiClassID = "DesktopPaneUI";

	transient DesktopManager desktopManager;

	private transient JInternalFrame selectedFrame = null;

	/**
	* Indicates that the entire contents of the item being dragged
	* should appear inside the desktop pane.
	*
	* @see #OUTLINE_DRAG_MODE
	* @see #setDragMode
	*/
	public static final int LIVE_DRAG_MODE = 0;

	/**
	* Indicates that an outline only of the item being dragged
	* should appear inside the desktop pane.
	*
	* @see #LIVE_DRAG_MODE
	* @see #setDragMode
	*/
	public static final int OUTLINE_DRAG_MODE = 1;

	private int dragMode = LIVE_DRAG_MODE;
	private boolean dragModeSet = false;
	private transient List<JInternalFrame> framesCache;
	private boolean componentOrderCheckingEnabled = true;
	private boolean componentOrderChanged = false;

	/**
	* Creates a new <code>JDesktopPane</code>.
	*/
	public JDesktopPane() {
	setUIProperty("opaque", Boolean.TRUE);
	setFocusCycleRoot(true);

	setFocusTraversalPolicy(new LayoutFocusTraversalPolicy() {
	public Component getDefaultComponent(Container c) {
	JInternalFrame jifArray[] = getAllFrames();
	Component comp = null;
	for (JInternalFrame jif : jifArray) {
	comp = jif.getFocusTraversalPolicy().getDefaultComponent(jif);
	if (comp != null) {
	break;
	}
	}
	return comp;
	}
	});
	updateUI();
	}

	/**
	* Returns the L&F object that renders this component.
	*
	* @return the <code>DesktopPaneUI</code> object that
	* renders this component
	*/
	public DesktopPaneUI getUI() {
	return (DesktopPaneUI)ui;
	}

	/**
	* Sets the L&F object that renders this component.
	*
	* @param ui the DesktopPaneUI L&F object
	* @see UIDefaults#getUI
	* @beaninfo
	* bound: true
	* hidden: true
	* attribute: visualUpdate true
	* description: The UI object that implements the Component's LookAndFeel.
	*/
	public void setUI(DesktopPaneUI ui) {
	super.setUI(ui);
	}

	/**
	* Sets the "dragging style" used by the desktop pane.
	* You may want to change to one mode or another for
	* performance or aesthetic reasons.
	*
	* @param dragMode the style of drag to use for items in the Desktop
	*
	* @see #LIVE_DRAG_MODE
	* @see #OUTLINE_DRAG_MODE
	*
	* @beaninfo
	* bound: true
	* description: Dragging style for internal frame children.
	* enum: LIVE_DRAG_MODE JDesktopPane.LIVE_DRAG_MODE
	* OUTLINE_DRAG_MODE JDesktopPane.OUTLINE_DRAG_MODE
	* @since 1.3
	*/
	public void setDragMode(int dragMode) {
	int oldDragMode = this.dragMode;
	this.dragMode = dragMode;
	firePropertyChange("dragMode", oldDragMode, this.dragMode);
	dragModeSet = true;
	}

	/**
	* Gets the current "dragging style" used by the desktop pane.
	* @return either <code>Live_DRAG_MODE</code> or
	* <code>OUTLINE_DRAG_MODE</code>
	* @see #setDragMode
	* @since 1.3
	*/
	public int getDragMode() {
	return dragMode;
	}

	/**
	* Returns the <code>DesktopManger</code> that handles
	* desktop-specific UI actions.
	*/
	public DesktopManager getDesktopManager() {
	return desktopManager;
	}

	/**
	* Sets the <code>DesktopManger</code> that will handle
	* desktop-specific UI actions. This may be overridden by
	* {@code LookAndFeel}.
	*
	* @param d the <code>DesktopManager</code> to use
	*
	* @beaninfo
	* bound: true
	* description: Desktop manager to handle the internal frames in the
	* desktop pane.
	*/
	public void setDesktopManager(DesktopManager d) {
	DesktopManager oldValue = desktopManager;
	desktopManager = d;
	firePropertyChange("desktopManager", oldValue, desktopManager);
	}

	/**
	* Notification from the <code>UIManager</code> that the L&F has changed.
	* Replaces the current UI object with the latest version from the
	* <code>UIManager</code>.
	*
	* @see JComponent#updateUI
	*/
	public void updateUI() {
	setUI((DesktopPaneUI)UIManager.getUI(this));
	}


	/**
	* Returns the name of the L&F class that renders this component.
	*
	* @return the string "DesktopPaneUI"
	* @see JComponent#getUIClassID
	* @see UIDefaults#getUI
	*/
	public String getUIClassID() {
	return uiClassID;
	}

	/**
	* Returns all <code>JInternalFrames</code> currently displayed in the
	* desktop. Returns iconified frames as well as expanded frames.
	*
	* @return an array of <code>JInternalFrame</code> objects
	*/
	public JInternalFrame[] getAllFrames() {
	return getAllFrames(this).toArray(new JInternalFrame[0]);
	}

	private static Collection<JInternalFrame> getAllFrames(Container parent) {
	int i, count;
	Collection<JInternalFrame> results = new LinkedHashSet<>();
	count = parent.getComponentCount();
	for (i = 0; i < count; i++) {
	Component next = parent.getComponent(i);
	if (next instanceof JInternalFrame) {
	results.add((JInternalFrame) next);
	} else if (next instanceof JInternalFrame.JDesktopIcon) {
	JInternalFrame tmp = ((JInternalFrame.JDesktopIcon) next).getInternalFrame();
	if (tmp != null) {
	results.add(tmp);
	}
	} else if (next instanceof Container) {
	results.addAll(getAllFrames((Container) next));
	}
	}
	return results;
	}

	/** Returns the currently active <code>JInternalFrame</code>
	* in this <code>JDesktopPane</code>, or <code>null</code>
	* if no <code>JInternalFrame</code> is currently active.
	*
	* @return the currently active <code>JInternalFrame</code> or
	* <code>null</code>
	* @since 1.3
	*/

	public JInternalFrame getSelectedFrame() {
	return selectedFrame;
	}

	/** Sets the currently active <code>JInternalFrame</code>
	* in this <code>JDesktopPane</code>. This method is used to bridge
	* the package gap between JDesktopPane and the platform implementation
	* code and should not be called directly. To visually select the frame
	* the client must call JInternalFrame.setSelected(true) to activate
	* the frame.
	* @see JInternalFrame#setSelected(boolean)
	*
	* @param f the internal frame that's currently selected
	* @since 1.3
	*/

	public void setSelectedFrame(JInternalFrame f) {
	selectedFrame = f;
	}

	/**
	* Returns all <code>JInternalFrames</code> currently displayed in the
	* specified layer of the desktop. Returns iconified frames as well
	* expanded frames.
	*
	* @param layer an int specifying the desktop layer
	* @return an array of <code>JInternalFrame</code> objects
	* @see JLayeredPane
	*/
	public JInternalFrame[] getAllFramesInLayer(int layer) {
	Collection<JInternalFrame> allFrames = getAllFrames(this);
	Iterator<JInternalFrame> iterator = allFrames.iterator();
	while (iterator.hasNext()) {
	if (iterator.next().getLayer() != layer) {
	iterator.remove();
	}
	}
	return allFrames.toArray(new JInternalFrame[0]);
	}

	private List<JInternalFrame> getFrames() {
	Component c;
	Set<ComponentPosition> set = new TreeSet<ComponentPosition>();
	for (int i = 0; i < getComponentCount(); i++) {
	c = getComponent(i);
	if (c instanceof JInternalFrame) {
	set.add(new ComponentPosition((JInternalFrame)c, getLayer(c),
	i));
	}
	else if (c instanceof JInternalFrame.JDesktopIcon) {
	c = ((JInternalFrame.JDesktopIcon)c).getInternalFrame();
	set.add(new ComponentPosition((JInternalFrame)c, getLayer(c),
	i));
	}
	}
	List<JInternalFrame> frames = new ArrayList<JInternalFrame>(
	set.size());
	for (ComponentPosition position : set) {
	frames.add(position.component);
	}
	return frames;
	}

	private static class ComponentPosition implements
	Comparable<ComponentPosition> {
	private final JInternalFrame component;
	private final int layer;
	private final int zOrder;

	ComponentPosition(JInternalFrame component, int layer, int zOrder) {
	this.component = component;
	this.layer = layer;
	this.zOrder = zOrder;
	}

	public int compareTo(ComponentPosition o) {
	int delta = o.layer - layer;
	if (delta == 0) {
	return zOrder - o.zOrder;
	}
	return delta;
	}
	}

	private JInternalFrame getNextFrame(JInternalFrame f, boolean forward) {
	verifyFramesCache();
	if (f == null) {
	return getTopInternalFrame();
	}
	int i = framesCache.indexOf(f);
	if (i == -1 \|\| framesCache.size() == 1) {
	/* error */
	return null;
	}
	if (forward) {
	// navigate to the next frame
	if (++i == framesCache.size()) {
	/* wrap */
	i = 0;
	}
	}
	else {
	// navigate to the previous frame
	if (--i == -1) {
	/* wrap */
	i = framesCache.size() - 1;
	}
	}
	return framesCache.get(i);
	}

	JInternalFrame getNextFrame(JInternalFrame f) {
	return getNextFrame(f, true);
	}

	private JInternalFrame getTopInternalFrame() {
	if (framesCache.size() == 0) {
	return null;
	}
	return framesCache.get(0);
	}

	private void updateFramesCache() {
	framesCache = getFrames();
	}

	private void verifyFramesCache() {
	// If framesCache is dirty, then recreate it.
	if (componentOrderChanged) {
	componentOrderChanged = false;
	updateFramesCache();
	}
	}

	/**
	* {@inheritDoc}
	*/
	@Override
	public void remove(Component comp) {
	super.remove(comp);
	updateFramesCache();
	}

	/**
	* Selects the next <code>JInternalFrame</code> in this desktop pane.
	*
	* @param forward a boolean indicating which direction to select in;
	* <code>true</code> for forward, <code>false</code> for
	* backward
	* @return the JInternalFrame that was selected or <code>null</code>
	* if nothing was selected
	* @since 1.6
	*/
	public JInternalFrame selectFrame(boolean forward) {
	JInternalFrame selectedFrame = getSelectedFrame();
	JInternalFrame frameToSelect = getNextFrame(selectedFrame, forward);
	if (frameToSelect == null) {
	return null;
	}
	// Maintain navigation traversal order until an
	// external stack change, such as a click on a frame.
	setComponentOrderCheckingEnabled(false);
	if (forward && selectedFrame != null) {
	selectedFrame.moveToBack(); // For Windows MDI fidelity.
	}
	try { frameToSelect.setSelected(true);
	} catch (PropertyVetoException pve) {}
	setComponentOrderCheckingEnabled(true);
	return frameToSelect;
	}

	/*
	* Sets whether component order checking is enabled.
	* @param enable a boolean value, where <code>true</code> means
	* a change in component order will cause a change in the keyboard
	* navigation order.
	* @since 1.6
	*/
	void setComponentOrderCheckingEnabled(boolean enable) {
	componentOrderCheckingEnabled = enable;
	}

	/**
	* {@inheritDoc}
	* @since 1.6
	*/
	protected void addImpl(Component comp, Object constraints, int index) {
	super.addImpl(comp, constraints, index);
	if (componentOrderCheckingEnabled) {
	if (comp instanceof JInternalFrame \|\|
	comp instanceof JInternalFrame.JDesktopIcon) {
	componentOrderChanged = true;
	}
	}
	}

	/**
	* {@inheritDoc}
	* @since 1.6
	*/
	public void remove(int index) {
	if (componentOrderCheckingEnabled) {
	Component comp = getComponent(index);
	if (comp instanceof JInternalFrame \|\|
	comp instanceof JInternalFrame.JDesktopIcon) {
	componentOrderChanged = true;
	}
	}
	super.remove(index);
	}

	/**
	* {@inheritDoc}
	* @since 1.6
	*/
	public void removeAll() {
	if (componentOrderCheckingEnabled) {
	int count = getComponentCount();
	for (int i = 0; i < count; i++) {
	Component comp = getComponent(i);
	if (comp instanceof JInternalFrame \|\|
	comp instanceof JInternalFrame.JDesktopIcon) {
	componentOrderChanged = true;
	break;
	}
	}
	}
	super.removeAll();
	}

	/**
	* {@inheritDoc}
	* @since 1.6
	*/
	public void setComponentZOrder(Component comp, int index) {
	super.setComponentZOrder(comp, index);
	if (componentOrderCheckingEnabled) {
	if (comp instanceof JInternalFrame \|\|
	comp instanceof JInternalFrame.JDesktopIcon) {
	componentOrderChanged = true;
	}
	}
	}

	/**
	* See readObject() and writeObject() in JComponent for more
	* information about serialization in Swing.
	*/
	private void writeObject(ObjectOutputStream s) throws IOException {
	s.defaultWriteObject();
	if (getUIClassID().equals(uiClassID)) {
	byte count = JComponent.getWriteObjCounter(this);
	JComponent.setWriteObjCounter(this, --count);
	if (count == 0 && ui != null) {
	ui.installUI(this);
	}
	}
	}

	void setUIProperty(String propertyName, Object value) {
	if (propertyName == "dragMode") {
	if (!dragModeSet) {
	setDragMode(((Integer)value).intValue());
	dragModeSet = false;
	}
	} else {
	super.setUIProperty(propertyName, value);
	}
	}

	/**
	* Returns a string representation of this <code>JDesktopPane</code>.
	* This method is intended to be used only for debugging purposes, and the
	* content and format of the returned string may vary between
	* implementations. The returned string may be empty but may not
	* be <code>null</code>.
	*
	* @return a string representation of this <code>JDesktopPane</code>
	*/
	protected String paramString() {
	String desktopManagerString = (desktopManager != null ?
	desktopManager.toString() : "");

	return super.paramString() +
	",desktopManager=" + desktopManagerString;
	}

	/////////////////
	// Accessibility support
	////////////////

	/**
	* Gets the <code>AccessibleContext</code> associated with this
	* <code>JDesktopPane</code>. For desktop panes, the
	* <code>AccessibleContext</code> takes the form of an
	* <code>AccessibleJDesktopPane</code>.
	* A new <code>AccessibleJDesktopPane</code> instance is created if necessary.
	*
	* @return an <code>AccessibleJDesktopPane</code> that serves as the
	* <code>AccessibleContext</code> of this <code>JDesktopPane</code>
	*/
	public AccessibleContext getAccessibleContext() {
	if (accessibleContext == null) {
	accessibleContext = new AccessibleJDesktopPane();
	}
	return accessibleContext;
	}

	/**
	* This class implements accessibility support for the
	* <code>JDesktopPane</code> class. It provides an implementation of the
	* Java Accessibility API appropriate to desktop pane user-interface
	* elements.
	* <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}.
	*/
	protected class AccessibleJDesktopPane extends AccessibleJComponent {

	/**
	* Get the role of this object.
	*
	* @return an instance of AccessibleRole describing the role of the
	* object
	* @see AccessibleRole
	*/
	public AccessibleRole getAccessibleRole() {
	return AccessibleRole.DESKTOP_PANE;
	}
	}
	}

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