/*
 * Copyright (c) 2005, 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
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package javax.swing;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.lang.reflect.*;
import java.lang.ref.WeakReference;
import java.util.*;

import com.sun.java.swing.SwingUtilities3;

import sun.awt.SubRegionShowable;
import sun.java2d.SunGraphics2D;
import sun.java2d.pipe.hw.ExtendedBufferCapabilities;
import sun.awt.SunToolkit;
import sun.util.logging.PlatformLogger;

A PaintManager implementation that uses a BufferStrategy for
rendering.
Author:
Scott Violet/**
 * A PaintManager implementation that uses a BufferStrategy for
 * rendering.
 *
 * @author Scott Violet
 */
class BufferStrategyPaintManager extends RepaintManager.PaintManager {
    //
    // All drawing is done to a BufferStrategy.  At the end of painting
    // (endPaint) the region that was painted is flushed to the screen
    // (using BufferStrategy.show).
    //
    // PaintManager.show is overriden to show directly from the
    // BufferStrategy (when using blit), if successful true is
    // returned and a paint event will not be generated.  To avoid
    // showing from the buffer while painting a locking scheme is
    // implemented.  When beginPaint is invoked the field painting is
    // set to true.  If painting is true and show is invoked we
    // immediately return false.  This is done to avoid blocking the
    // toolkit thread while painting happens.  In a similar way when
    // show is invoked the field showing is set to true, beginPaint
    // will then block until showing is true.  This scheme ensures we
    // only ever have one thread using the BufferStrategy and it also
    // ensures the toolkit thread remains as responsive as possible.
    //
    // If we're using a flip strategy the contents of the backbuffer may
    // have changed and so show only attempts to show from the backbuffer
    // if we get a blit strategy.
    //

    //
    // Methods used to create BufferStrategy for Applets.
    //
    private static Method COMPONENT_CREATE_BUFFER_STRATEGY_METHOD;
    private static Method COMPONENT_GET_BUFFER_STRATEGY_METHOD;

    private static final PlatformLogger LOGGER = PlatformLogger.getLogger(
                           "javax.swing.BufferStrategyPaintManager");

    
List of BufferInfos.  We don't use a Map primarily because
there are typically only a handful of top level components making
a Map overkill.
/**
     * List of BufferInfos.  We don't use a Map primarily because
     * there are typically only a handful of top level components making
     * a Map overkill.
     */
    private ArrayList<BufferInfo> bufferInfos;

    
Indicates beginPaint has been invoked.  This is
set to true for the life of beginPaint/endPaint pair.
/**
     * Indicates <code>beginPaint</code> has been invoked.  This is
     * set to true for the life of beginPaint/endPaint pair.
     */
    private boolean painting;
    
Indicates we're in the process of showing.  All painting, on the EDT,
is blocked while this is true.
/**
     * Indicates we're in the process of showing.  All painting, on the EDT,
     * is blocked while this is true.
     */
    private boolean showing;

    //
    // Region that we need to flush.  When beginPaint is called these are
    // reset and any subsequent calls to paint/copyArea then update these
    // fields accordingly.  When endPaint is called we then try and show
    // the accumulated region.
    // These fields are in the coordinate system of the root.
    //
    private int accumulatedX;
    private int accumulatedY;
    private int accumulatedMaxX;
    private int accumulatedMaxY;

    //
    // The following fields are set by prepare
    //

    
Farthest JComponent ancestor for the current paint/copyArea.
/**
     * Farthest JComponent ancestor for the current paint/copyArea.
     */
    private JComponent rootJ;
    
Location of component being painted relative to root.
/**
     * Location of component being painted relative to root.
     */
    private int xOffset;
    
Location of component being painted relative to root.
/**
     * Location of component being painted relative to root.
     */
    private int yOffset;
    
Graphics from the BufferStrategy.
/**
     * Graphics from the BufferStrategy.
     */
    private Graphics bsg;
    
BufferStrategy currently being used.
/**
     * BufferStrategy currently being used.
     */
    private BufferStrategy bufferStrategy;
    
BufferInfo corresponding to root.
/**
     * BufferInfo corresponding to root.
     */
    private BufferInfo bufferInfo;

    
Set to true if the bufferInfo needs to be disposed when current
paint loop is done.
/**
     * Set to true if the bufferInfo needs to be disposed when current
     * paint loop is done.
     */
    private boolean disposeBufferOnEnd;

    private static Method getGetBufferStrategyMethod() {
        if (COMPONENT_GET_BUFFER_STRATEGY_METHOD == null) {
            getMethods();
        }
        return COMPONENT_GET_BUFFER_STRATEGY_METHOD;
    }

    private static Method getCreateBufferStrategyMethod() {
        if (COMPONENT_CREATE_BUFFER_STRATEGY_METHOD == null) {
            getMethods();
        }
        return COMPONENT_CREATE_BUFFER_STRATEGY_METHOD;
    }

    private static void getMethods() {
        java.security.AccessController.doPrivileged(
                            new java.security.PrivilegedAction<Object>() {
            public Object run() {
                try {
                    COMPONENT_CREATE_BUFFER_STRATEGY_METHOD = Component.class.
                              getDeclaredMethod("createBufferStrategy",
                                                new Class[] { int.class,
                                                BufferCapabilities.class });
                    COMPONENT_CREATE_BUFFER_STRATEGY_METHOD.
                                            setAccessible(true);
                    COMPONENT_GET_BUFFER_STRATEGY_METHOD = Component.class.
                              getDeclaredMethod("getBufferStrategy");
                    COMPONENT_GET_BUFFER_STRATEGY_METHOD.setAccessible(true);
                } catch (SecurityException e) {
                    assert false;
                } catch (NoSuchMethodException nsme) {
                    assert false;
                }
                return null;
            }
        });
    }

    BufferStrategyPaintManager() {
        bufferInfos = new ArrayList<BufferInfo>(1);
    }

    //
    // PaintManager methods
    //

    
Cleans up any created BufferStrategies.
/**
     * Cleans up any created BufferStrategies.
     */
    protected void dispose() {
        // dipose can be invoked at any random time. To avoid
        // threading dependancies we do the actual diposing via an
        // invokeLater.
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                java.util.List<BufferInfo> bufferInfos;
                synchronized(BufferStrategyPaintManager.this) {
                    while (showing) {
                        try {
                            BufferStrategyPaintManager.this.wait();
                        } catch (InterruptedException ie) {
                        }
                    }
                    bufferInfos = BufferStrategyPaintManager.this.bufferInfos;
                    BufferStrategyPaintManager.this.bufferInfos = null;
                }
                dispose(bufferInfos);
            }
        });
    }

    private void dispose(java.util.List<BufferInfo> bufferInfos) {
        if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
            LOGGER.finer("BufferStrategyPaintManager disposed",
                         new RuntimeException());
        }
        if (bufferInfos != null) {
            for (BufferInfo bufferInfo : bufferInfos) {
                bufferInfo.dispose();
            }
        }
    }

    
Shows the specified region of the back buffer.  This will return
true if successful, false otherwise.  This is invoked on the
toolkit thread in response to an expose event.
/**
     * Shows the specified region of the back buffer.  This will return
     * true if successful, false otherwise.  This is invoked on the
     * toolkit thread in response to an expose event.
     */
    public boolean show(Container c, int x, int y, int w, int h) {
        synchronized(this) {
            if (painting) {
                // Don't show from backbuffer while in the process of
                // painting.
                return false;
            }
            showing = true;
        }
        try {
            BufferInfo info = getBufferInfo(c);
            BufferStrategy bufferStrategy;
            if (info != null && info.isInSync() &&
                (bufferStrategy = info.getBufferStrategy(false)) != null) {
                SubRegionShowable bsSubRegion =
                        (SubRegionShowable)bufferStrategy;
                boolean paintAllOnExpose = info.getPaintAllOnExpose();
                info.setPaintAllOnExpose(false);
                if (bsSubRegion.showIfNotLost(x, y, (x + w), (y + h))) {
                    return !paintAllOnExpose;
                }
                // Mark the buffer as needing to be repainted.  We don't
                // immediately do a repaint as this method will return false
                // indicating a PaintEvent should be generated which will
                // trigger a complete repaint.
                bufferInfo.setContentsLostDuringExpose(true);
            }
        }
        finally {
            synchronized(this) {
                showing = false;
                notifyAll();
            }
        }
        return false;
    }

    public boolean paint(JComponent paintingComponent,
                         JComponent bufferComponent, Graphics g,
                         int x, int y, int w, int h) {
        Container root = fetchRoot(paintingComponent);

        if (prepare(paintingComponent, root, true, x, y, w, h)) {
            if ((g instanceof SunGraphics2D) &&
                    ((SunGraphics2D)g).getDestination() == root) {
                // BufferStrategy may have already constrained the Graphics. To
                // account for that we revert the constrain, then apply a
                // constrain for Swing on top of that.
                int cx = ((SunGraphics2D)bsg).constrainX;
                int cy = ((SunGraphics2D)bsg).constrainY;
                if (cx != 0 || cy != 0) {
                    bsg.translate(-cx, -cy);
                }
                ((SunGraphics2D)bsg).constrain(xOffset + cx, yOffset + cy,
                                               x + w, y + h);
                bsg.setClip(x, y, w, h);
                paintingComponent.paintToOffscreen(bsg, x, y, w, h,
                                                   x + w, y + h);
                accumulate(xOffset + x, yOffset + y, w, h);
                return true;
            } else {
                // Assume they are going to eventually render to the screen.
                // This disables showing from backbuffer until a complete
                // repaint occurs.
                bufferInfo.setInSync(false);
                // Fall through to old rendering.
            }
        }
        // Invalid root, do what Swing has always done.
        if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
            LOGGER.finer("prepare failed");
        }
        return super.paint(paintingComponent, bufferComponent, g, x, y, w, h);
    }

    public void copyArea(JComponent c, Graphics g, int x, int y, int w, int h,
                         int deltaX, int deltaY, boolean clip) {
        // Note: this method is only called internally and we know that
        // g is from a heavyweight Component, so no check is necessary as
        // it is in paint() above.
        //
        // If the buffer isn't in sync there is no point in doing a copyArea,
        // it has garbage.
        Container root = fetchRoot(c);

        if (prepare(c, root, false, 0, 0, 0, 0) && bufferInfo.isInSync()) {
            if (clip) {
                Rectangle cBounds = c.getVisibleRect();
                int relX = xOffset + x;
                int relY = yOffset + y;
                bsg.clipRect(xOffset + cBounds.x,
                             yOffset + cBounds.y,
                             cBounds.width, cBounds.height);
                bsg.copyArea(relX, relY, w, h, deltaX, deltaY);
            }
            else {
                bsg.copyArea(xOffset + x, yOffset + y, w, h, deltaX,
                             deltaY);
            }
            accumulate(x + xOffset + deltaX, y + yOffset + deltaY, w, h);
        } else {
            if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                LOGGER.finer("copyArea: prepare failed or not in sync");
            }
            // Prepare failed, or not in sync. By calling super.copyArea
            // we'll copy on screen. We need to flush any pending paint to
            // the screen otherwise we'll do a copyArea on the wrong thing.
            if (!flushAccumulatedRegion()) {
                // Flush failed, copyArea will be copying garbage,
                // force repaint of all.
                rootJ.repaint();
            } else {
                super.copyArea(c, g, x, y, w, h, deltaX, deltaY, clip);
            }
        }
    }

    public void beginPaint() {
        synchronized(this) {
            painting = true;
            // Make sure another thread isn't attempting to show from
            // the back buffer.
            while(showing) {
                try {
                    wait();
                } catch (InterruptedException ie) {
                }
            }
        }
        if (LOGGER.isLoggable(PlatformLogger.Level.FINEST)) {
            LOGGER.finest("beginPaint");
        }
        // Reset the area that needs to be painted.
        resetAccumulated();
    }

    public void endPaint() {
        if (LOGGER.isLoggable(PlatformLogger.Level.FINEST)) {
            LOGGER.finest("endPaint: region " + accumulatedX + " " +
                       accumulatedY + " " +  accumulatedMaxX + " " +
                       accumulatedMaxY);
        }
        if (painting) {
            if (!flushAccumulatedRegion()) {
                if (!isRepaintingRoot()) {
                    repaintRoot(rootJ);
                }
                else {
                    // Contents lost twice in a row, punt.
                    resetDoubleBufferPerWindow();
                    // In case we've left junk on the screen, force a repaint.
                    rootJ.repaint();
                }
            }
        }

        BufferInfo toDispose = null;
        synchronized(this) {
            painting = false;
            if (disposeBufferOnEnd) {
                disposeBufferOnEnd = false;
                toDispose = bufferInfo;
                bufferInfos.remove(toDispose);
            }
        }
        if (toDispose != null) {
            toDispose.dispose();
        }
    }

    
Renders the BufferStrategy to the screen.
Returns:
true if successful, false otherwise./**
     * Renders the BufferStrategy to the screen.
     *
     * @return true if successful, false otherwise.
     */
    private boolean flushAccumulatedRegion() {
        boolean success = true;
        if (accumulatedX != Integer.MAX_VALUE) {
            SubRegionShowable bsSubRegion = (SubRegionShowable)bufferStrategy;
            boolean contentsLost = bufferStrategy.contentsLost();
            if (!contentsLost) {
                bsSubRegion.show(accumulatedX, accumulatedY,
                                 accumulatedMaxX, accumulatedMaxY);
                contentsLost = bufferStrategy.contentsLost();
            }
            if (contentsLost) {
                if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                    LOGGER.finer("endPaint: contents lost");
                }
                // Shown region was bogus, mark buffer as out of sync.
                bufferInfo.setInSync(false);
                success = false;
            }
        }
        resetAccumulated();
        return success;
    }

    private void resetAccumulated() {
        accumulatedX = Integer.MAX_VALUE;
        accumulatedY = Integer.MAX_VALUE;
        accumulatedMaxX = 0;
        accumulatedMaxY = 0;
    }

    
Invoked when the double buffering or useTrueDoubleBuffering
changes for a JRootPane.  If the rootpane is not double
buffered, or true double buffering changes we throw out any
cache we may have.
/**
     * Invoked when the double buffering or useTrueDoubleBuffering
     * changes for a JRootPane.  If the rootpane is not double
     * buffered, or true double buffering changes we throw out any
     * cache we may have.
     */
    public void doubleBufferingChanged(final JRootPane rootPane) {
        if ((!rootPane.isDoubleBuffered() ||
                !rootPane.getUseTrueDoubleBuffering()) &&
                rootPane.getParent() != null) {
            if (!SwingUtilities.isEventDispatchThread()) {
                Runnable updater = new Runnable() {
                    public void run() {
                        doubleBufferingChanged0(rootPane);
                    }
                };
                SwingUtilities.invokeLater(updater);
            }
            else {
                doubleBufferingChanged0(rootPane);
            }
        }
    }

    
Does the work for doubleBufferingChanged.
/**
     * Does the work for doubleBufferingChanged.
     */
    private void doubleBufferingChanged0(JRootPane rootPane) {
        // This will only happen on the EDT.
        BufferInfo info;
        synchronized(this) {
            // Make sure another thread isn't attempting to show from
            // the back buffer.
            while(showing) {
                try {
                    wait();
                } catch (InterruptedException ie) {
                }
            }
            info = getBufferInfo(rootPane.getParent());
            if (painting && bufferInfo == info) {
                // We're in the process of painting and the user grabbed
                // the Graphics. If we dispose now, endPaint will attempt
                // to show a bogus BufferStrategy. Set a flag so that
                // endPaint knows it needs to dispose this buffer.
                disposeBufferOnEnd = true;
                info = null;
            } else if (info != null) {
                bufferInfos.remove(info);
            }
        }
        if (info != null) {
            info.dispose();
        }
    }

    
Calculates information common to paint/copyArea.
Returns:
true if should use buffering per window in painting./**
     * Calculates information common to paint/copyArea.
     *
     * @return true if should use buffering per window in painting.
     */
    private boolean prepare(JComponent c, Container root, boolean isPaint, int x, int y,
                            int w, int h) {
        if (bsg != null) {
            bsg.dispose();
            bsg = null;
        }
        bufferStrategy = null;
        if (root != null) {
            boolean contentsLost = false;
            BufferInfo bufferInfo = getBufferInfo(root);
            if (bufferInfo == null) {
                contentsLost = true;
                bufferInfo = new BufferInfo(root);
                bufferInfos.add(bufferInfo);
                if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                    LOGGER.finer("prepare: new BufferInfo: " + root);
                }
            }
            this.bufferInfo = bufferInfo;
            if (!bufferInfo.hasBufferStrategyChanged()) {
                bufferStrategy = bufferInfo.getBufferStrategy(true);
                if (bufferStrategy != null) {
                    bsg = bufferStrategy.getDrawGraphics();
                    if (bufferStrategy.contentsRestored()) {
                        contentsLost = true;
                        if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                            LOGGER.finer("prepare: contents restored in prepare");
                        }
                    }
                }
                else {
                    // Couldn't create BufferStrategy, fallback to normal
                    // painting.
                    return false;
                }
                if (bufferInfo.getContentsLostDuringExpose()) {
                    contentsLost = true;
                    bufferInfo.setContentsLostDuringExpose(false);
                    if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                        LOGGER.finer("prepare: contents lost on expose");
                    }
                }
                if (isPaint && c == rootJ && x == 0 && y == 0 &&
                      c.getWidth() == w && c.getHeight() == h) {
                    bufferInfo.setInSync(true);
                }
                else if (contentsLost) {
                    // We either recreated the BufferStrategy, or the contents
                    // of the buffer strategy were restored.  We need to
                    // repaint the root pane so that the back buffer is in sync
                    // again.
                    bufferInfo.setInSync(false);
                    if (!isRepaintingRoot()) {
                        repaintRoot(rootJ);
                    }
                    else {
                        // Contents lost twice in a row, punt
                        resetDoubleBufferPerWindow();
                    }
                }
                return (bufferInfos != null);
            }
        }
        return false;
    }

    private Container fetchRoot(JComponent c) {
        boolean encounteredHW = false;
        rootJ = c;
        Container root = c;
        xOffset = yOffset = 0;
        while (root != null &&
               (!(root instanceof Window) &&
                !SunToolkit.isInstanceOf(root, "java.applet.Applet"))) {
            xOffset += root.getX();
            yOffset += root.getY();
            root = root.getParent();
            if (root != null) {
                if (root instanceof JComponent) {
                    rootJ = (JComponent)root;
                }
                else if (!root.isLightweight()) {
                    if (!encounteredHW) {
                        encounteredHW = true;
                    }
                    else {
                        // We've encountered two hws now and may have
                        // a containment hierarchy with lightweights containing
                        // heavyweights containing other lightweights.
                        // Heavyweights poke holes in lightweight
                        // rendering so that if we call show on the BS
                        // (which is associated with the Window) you will
                        // not see the contents over any child
                        // heavyweights.  If we didn't do this when we
                        // went to show the descendants of the nested hw
                        // you would see nothing, so, we bail out here.
                        return null;
                    }
                }
            }
        }
        if ((root instanceof RootPaneContainer) &&
            (rootJ instanceof JRootPane)) {
            // We're in a Swing heavyeight (JFrame/JWindow...), use double
            // buffering if double buffering enabled on the JRootPane and
            // the JRootPane wants true double buffering.
            if (rootJ.isDoubleBuffered() &&
                    ((JRootPane)rootJ).getUseTrueDoubleBuffering()) {
                // Whether or not a component is double buffered is a
                // bit tricky with Swing. This gives a good approximation
                // of the various ways to turn on double buffering for
                // components.
                return root;
            }
        }
        // Don't do true double buffering.
        return null;
    }

    
Turns off double buffering per window.
/**
     * Turns off double buffering per window.
     */
    private void resetDoubleBufferPerWindow() {
        if (bufferInfos != null) {
            dispose(bufferInfos);
            bufferInfos = null;
            repaintManager.setPaintManager(null);
        }
    }

    
Returns the BufferInfo for the specified root or null if one
hasn't been created yet.
/**
     * Returns the BufferInfo for the specified root or null if one
     * hasn't been created yet.
     */
    private BufferInfo getBufferInfo(Container root) {
        for (int counter = bufferInfos.size() - 1; counter >= 0; counter--) {
            BufferInfo bufferInfo = bufferInfos.get(counter);
            Container biRoot = bufferInfo.getRoot();
            if (biRoot == null) {
                // Window gc'ed
                bufferInfos.remove(counter);
                if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                    LOGGER.finer("BufferInfo pruned, root null");
                }
            }
            else if (biRoot == root) {
                return bufferInfo;
            }
        }
        return null;
    }

    private void accumulate(int x, int y, int w, int h) {
        accumulatedX = Math.min(x, accumulatedX);
        accumulatedY = Math.min(y, accumulatedY);
        accumulatedMaxX = Math.max(accumulatedMaxX, x + w);
        accumulatedMaxY = Math.max(accumulatedMaxY, y + h);
    }



    
BufferInfo is used to track the BufferStrategy being used for
a particular Component.  In addition to tracking the BufferStrategy
it will install a WindowListener and ComponentListener.  When the
component is hidden/iconified the buffer is marked as needing to be
completely repainted.
/**
     * BufferInfo is used to track the BufferStrategy being used for
     * a particular Component.  In addition to tracking the BufferStrategy
     * it will install a WindowListener and ComponentListener.  When the
     * component is hidden/iconified the buffer is marked as needing to be
     * completely repainted.
     */
    private class BufferInfo extends ComponentAdapter implements
                               WindowListener {
        // NOTE: This class does NOT hold a direct reference to the root, if it
        // did there would be a cycle between the BufferPerWindowPaintManager
        // and the Window so that it could never be GC'ed
        //
        // Reference to BufferStrategy is referenced via WeakReference for
        // same reason.
        private WeakReference<BufferStrategy> weakBS;
        private WeakReference<Container> root;
        // Indicates whether or not the backbuffer and display are in sync.
        // This is set to true when a full repaint on the rootpane is done.
        private boolean inSync;
        // Indicates the contents were lost during and expose event.
        private boolean contentsLostDuringExpose;
        // Indicates we need to generate a paint event on expose.
        private boolean paintAllOnExpose;


        public BufferInfo(Container root) {
            this.root = new WeakReference<Container>(root);
            root.addComponentListener(this);
            if (root instanceof Window) {
                ((Window)root).addWindowListener(this);
            }
        }

        public void setPaintAllOnExpose(boolean paintAllOnExpose) {
            this.paintAllOnExpose = paintAllOnExpose;
        }

        public boolean getPaintAllOnExpose() {
            return paintAllOnExpose;
        }

        public void setContentsLostDuringExpose(boolean value) {
            contentsLostDuringExpose = value;
        }

        public boolean getContentsLostDuringExpose() {
            return contentsLostDuringExpose;
        }

        public void setInSync(boolean inSync) {
            this.inSync = inSync;
        }

        
Whether or not the contents of the buffer strategy
is in sync with the window.  This is set to true when the root
pane paints all, and false when contents are lost/restored.
/**
         * Whether or not the contents of the buffer strategy
         * is in sync with the window.  This is set to true when the root
         * pane paints all, and false when contents are lost/restored.
         */
        public boolean isInSync() {
            return inSync;
        }

        
Returns the Root (Window or Applet) that this BufferInfo references.
/**
         * Returns the Root (Window or Applet) that this BufferInfo references.
         */
        public Container getRoot() {
            return (root == null) ? null : root.get();
        }

        
Returns the BufferStartegy.  This will return null if
the BufferStartegy hasn't been created and create is
false, or if there is a problem in creating the
BufferStartegy.
Params:
create – If true, and the BufferStartegy is currently null,
              one will be created./**
         * Returns the BufferStartegy.  This will return null if
         * the BufferStartegy hasn't been created and <code>create</code> is
         * false, or if there is a problem in creating the
         * <code>BufferStartegy</code>.
         *
         * @param create If true, and the BufferStartegy is currently null,
         *               one will be created.
         */
        public BufferStrategy getBufferStrategy(boolean create) {
            BufferStrategy bs = (weakBS == null) ? null : weakBS.get();
            if (bs == null && create) {
                bs = createBufferStrategy();
                if (bs != null) {
                    weakBS = new WeakReference<BufferStrategy>(bs);
                }
                if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                    LOGGER.finer("getBufferStrategy: created bs: " + bs);
                }
            }
            return bs;
        }

        
Returns true if the buffer strategy of the component differs
from current buffer strategy.
/**
         * Returns true if the buffer strategy of the component differs
         * from current buffer strategy.
         */
        public boolean hasBufferStrategyChanged() {
            Container root = getRoot();
            if (root != null) {
                BufferStrategy ourBS = null;
                BufferStrategy componentBS = null;

                ourBS = getBufferStrategy(false);
                if (root instanceof Window) {
                    componentBS = ((Window)root).getBufferStrategy();
                }
                else {
                    try {
                        componentBS = (BufferStrategy)
                                 getGetBufferStrategyMethod().invoke(root);
                    } catch (InvocationTargetException ite) {
                        assert false;
                    } catch (IllegalArgumentException iae) {
                        assert false;
                    } catch (IllegalAccessException iae2) {
                        assert false;
                    }
                }
                if (componentBS != ourBS) {
                    // Component has a different BS, dispose ours.
                    if (ourBS != null) {
                        ourBS.dispose();
                    }
                    weakBS = null;
                    return true;
                }
            }
            return false;
        }

        
Creates the BufferStrategy.  If the appropriate system property
has been set we'll try for flip first and then we'll try for
blit.
/**
         * Creates the BufferStrategy.  If the appropriate system property
         * has been set we'll try for flip first and then we'll try for
         * blit.
         */
        private BufferStrategy createBufferStrategy() {
            Container root = getRoot();
            if (root == null) {
                return null;
            }
            BufferStrategy bs = null;
            if (SwingUtilities3.isVsyncRequested(root)) {
                bs = createBufferStrategy(root, true);
                if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                    LOGGER.finer("createBufferStrategy: using vsynced strategy");
                }
            }
            if (bs == null) {
                bs = createBufferStrategy(root, false);
            }
            if (!(bs instanceof SubRegionShowable)) {
                // We do this for two reasons:
                // 1. So that we know we can cast to SubRegionShowable and
                //    invoke show with the minimal region to update
                // 2. To avoid the possibility of invoking client code
                //    on the toolkit thread.
                bs = null;
            }
            return bs;
        }

        // Creates and returns a buffer strategy.  If
        // there is a problem creating the buffer strategy this will
        // eat the exception and return null.
        private BufferStrategy createBufferStrategy(Container root,
                boolean isVsynced) {
            BufferCapabilities caps;
            if (isVsynced) {
                caps = new ExtendedBufferCapabilities(
                    new ImageCapabilities(true), new ImageCapabilities(true),
                    BufferCapabilities.FlipContents.COPIED,
                    ExtendedBufferCapabilities.VSyncType.VSYNC_ON);
            } else {
                caps = new BufferCapabilities(
                    new ImageCapabilities(true), new ImageCapabilities(true),
                    null);
            }
            BufferStrategy bs = null;
            if (SunToolkit.isInstanceOf(root, "java.applet.Applet")) {
                try {
                    getCreateBufferStrategyMethod().invoke(root, 2, caps);
                    bs = (BufferStrategy)getGetBufferStrategyMethod().
                                            invoke(root);
                } catch (InvocationTargetException ite) {
                    // Type is not supported
                    if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                        LOGGER.finer("createBufferStratety failed",
                                     ite);
                    }
                } catch (IllegalArgumentException iae) {
                    assert false;
                } catch (IllegalAccessException iae2) {
                    assert false;
                }
            }
            else {
                try {
                    ((Window)root).createBufferStrategy(2, caps);
                    bs = ((Window)root).getBufferStrategy();
                } catch (AWTException e) {
                    // Type not supported
                    if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                        LOGGER.finer("createBufferStratety failed",
                                     e);
                    }
                }
            }
            return bs;
        }

        
Cleans up and removes any references.
/**
         * Cleans up and removes any references.
         */
        public void dispose() {
            Container root = getRoot();
            if (LOGGER.isLoggable(PlatformLogger.Level.FINER)) {
                LOGGER.finer("disposed BufferInfo for: " + root);
            }
            if (root != null) {
                root.removeComponentListener(this);
                if (root instanceof Window) {
                    ((Window)root).removeWindowListener(this);
                }
                BufferStrategy bs = getBufferStrategy(false);
                if (bs != null) {
                    bs.dispose();
                }
            }
            this.root = null;
            weakBS = null;
        }

        // We mark the buffer as needing to be painted on a hide/iconify
        // because the developer may have conditionalized painting based on
        // visibility.
        // Ideally we would also move to having the BufferStrategy being
        // a SoftReference in Component here, but that requires changes to
        // Component and the like.
        public void componentHidden(ComponentEvent e) {
            Container root = getRoot();
            if (root != null && root.isVisible()) {
                // This case will only happen if a developer calls
                // hide immediately followed by show.  In this case
                // the event is delivered after show and the window
                // will still be visible.  If a developer altered the
                // contents of the window between the hide/show
                // invocations we won't recognize we need to paint and
                // the contents would be bogus.  Calling repaint here
                // fixs everything up.
                root.repaint();
            }
            else {
                setPaintAllOnExpose(true);
            }
        }

        public void windowIconified(WindowEvent e) {
            setPaintAllOnExpose(true);
        }

        // On a dispose we chuck everything.
        public void windowClosed(WindowEvent e) {
            // Make sure we're not showing.
            synchronized(BufferStrategyPaintManager.this) {
                while (showing) {
                    try {
                        BufferStrategyPaintManager.this.wait();
                    } catch (InterruptedException ie) {
                    }
                }
                bufferInfos.remove(this);
            }
            dispose();
        }

        public void windowOpened(WindowEvent e) {
        }

        public void windowClosing(WindowEvent e) {
        }

        public void windowDeiconified(WindowEvent e) {
        }

        public void windowActivated(WindowEvent e) {
        }

        public void windowDeactivated(WindowEvent e) {
        }
    }
}