https://openjdk.java.net/ 
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 *
 * 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).
 *
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 *
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package sun.awt;

import java.awt.Font;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.HeadlessException;
import java.awt.Toolkit;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;

import sun.java2d.MacosxSurfaceManagerFactory;
import sun.java2d.SunGraphicsEnvironment;
import sun.java2d.SurfaceManagerFactory;


This is an implementation of a GraphicsEnvironment object for the default
local GraphicsEnvironment used by the Java Runtime Environment for Mac OS X
GUI environments.

See Also:
/**
 * This is an implementation of a GraphicsEnvironment object for the default
 * local GraphicsEnvironment used by the Java Runtime Environment for Mac OS X
 * GUI environments.
 *
 * @see GraphicsDevice
 * @see GraphicsConfiguration
 */
public final class CGraphicsEnvironment extends SunGraphicsEnvironment {

    
Fetch an array of all valid CoreGraphics display identifiers.

/**
     * Fetch an array of all valid CoreGraphics display identifiers.
     */
    private static native int[] getDisplayIDs();

    
Fetch the CoreGraphics display ID for the 'main' display.

/**
     * Fetch the CoreGraphics display ID for the 'main' display.
     */
    private static native int getMainDisplayID();

    
Noop function that just acts as an entry point for someone to force a
static initialization of this class.

/**
     * Noop function that just acts as an entry point for someone to force a
     * static initialization of this class.
     */
    public static void init() { }

    static {
        // Load libraries and initialize the Toolkit.
        Toolkit.getDefaultToolkit();
        // Install the correct surface manager factory.
        SurfaceManagerFactory.setInstance(new MacosxSurfaceManagerFactory());
    }

    
Register the instance with CGDisplayRegisterReconfigurationCallback().
The registration uses a weak global reference -- if our instance is
garbage collected, the reference will be dropped.

Returns:Return the registration context (a pointer).
/**
     * Register the instance with CGDisplayRegisterReconfigurationCallback().
     * The registration uses a weak global reference -- if our instance is
     * garbage collected, the reference will be dropped.
     *
     * @return Return the registration context (a pointer).
     */
    private native long registerDisplayReconfiguration();

    
Remove the instance's registration with CGDisplayRemoveReconfigurationCallback()

/**
     * Remove the instance's registration with CGDisplayRemoveReconfigurationCallback()
     */
    private native void deregisterDisplayReconfiguration(long context);

    
Available CoreGraphics displays. 
/** Available CoreGraphics displays. */
    private final Map<Integer, CGraphicsDevice> devices = new HashMap<>(5);
    
The key in the devices for the main display. 
/**
     * The key in the {@link #devices} for the main display.
     */
    private int mainDisplayID;

    
Reference to the display reconfiguration callback context. 
/** Reference to the display reconfiguration callback context. */
    private final long displayReconfigContext;

    // list of invalidated graphics devices (those which were removed)
    private List<WeakReference<CGraphicsDevice>> oldDevices = new ArrayList<>();

    
Construct a new instance.

/**
     * Construct a new instance.
     */
    public CGraphicsEnvironment() {
        if (isHeadless()) {
            displayReconfigContext = 0L;
            return;
        }

        /* Populate the device table */
        rebuildDevices();

        /* Register our display reconfiguration listener */
        displayReconfigContext = registerDisplayReconfiguration();
        if (displayReconfigContext == 0L) {
            throw new RuntimeException("Could not register CoreGraphics display reconfiguration callback");
        }
    }

    
Updates the list of devices and notify listeners.

/**
     * Updates the list of devices and notify listeners.
     */
    private void rebuildDevices() {
        initDevices();
        displayChanged();
    }

    
Called by the CoreGraphics Display Reconfiguration Callback.

Params:
  • displayId – CoreGraphics displayId
  • removed –   true if displayId was removed, false otherwise.
/**
     * Called by the CoreGraphics Display Reconfiguration Callback.
     *
     * @param displayId CoreGraphics displayId
     * @param removed   true if displayId was removed, false otherwise.
     */
    void _displayReconfiguration(int displayId, boolean removed) {
        // we ignore the passed parameters and check removed devices ourself
        // Note that it is possible that this callback is called when the
        // monitors are not added nor removed, but when the video card is
        // switched to/from the discrete video card, so we should try to map the
        // old to the new devices.
        rebuildDevices();
    }

    @Override
    @SuppressWarnings("deprecation")
    protected void finalize() throws Throwable {
        try {
            super.finalize();
        } finally {
            deregisterDisplayReconfiguration(displayReconfigContext);
        }
    }

    
(Re)create all CGraphicsDevices, reuses a devices if it is possible.

/**
     * (Re)create all CGraphicsDevices, reuses a devices if it is possible.
     */
    private synchronized void initDevices() {
        Map<Integer, CGraphicsDevice> old = new HashMap<>(devices);
        devices.clear();
        mainDisplayID = getMainDisplayID();

        // initialization of the graphics device may change list of displays on
        // hybrid systems via an activation of discrete video.
        // So, we initialize the main display first, then retrieve actual list
        // of displays, and then recheck the main display again.
        if (!old.containsKey(mainDisplayID)) {
            old.put(mainDisplayID, new CGraphicsDevice(mainDisplayID));
        }

        int[] displayIDs = getDisplayIDs();
        if (displayIDs.length == 0) {
            // we could throw AWTError in this case.
            displayIDs = new int[]{mainDisplayID};
        }
        for (int id : displayIDs) {
            devices.put(id, old.containsKey(id) ? old.remove(id)
                                                : new CGraphicsDevice(id));
        }
        // fetch the main display again, the old value might be outdated
        mainDisplayID = getMainDisplayID();

        // unlikely but make sure the main screen is in the list of screens,
        // most probably one more "displayReconfiguration" is on the road if not
        if (!devices.containsKey(mainDisplayID)) {
            mainDisplayID = displayIDs[0]; // best we can do
        }
        // if a device was not reused it should be invalidated
        for (CGraphicsDevice gd : old.values()) {
            oldDevices.add(new WeakReference<>(gd));
        }
        // Need to notify old devices, in case the user hold the reference to it
        for (ListIterator<WeakReference<CGraphicsDevice>> it =
             oldDevices.listIterator(); it.hasNext(); ) {
            CGraphicsDevice gd = it.next().get();
            if (gd != null) {
                // If the old device has the same bounds as some new device
                // then map that old device to the new, or to the main screen.
                CGraphicsDevice similarDevice = getSimilarDevice(gd);
                if (similarDevice == null) {
                    gd.invalidate(devices.get(mainDisplayID));
                } else {
                    gd.invalidate(similarDevice);
                }
                gd.displayChanged();
            } else {
                // no more references to this device, remove it
                it.remove();
            }
        }
    }

    private CGraphicsDevice getSimilarDevice(CGraphicsDevice old) {
        for (CGraphicsDevice device : devices.values()) {
            if (device.getBounds().equals(old.getBounds())) {
                // for now we will use the bounds only
                return device;
            }
        }
        return null;
    }

    @Override
    public synchronized GraphicsDevice getDefaultScreenDevice() throws HeadlessException {
        return devices.get(mainDisplayID);
    }

    @Override
    public synchronized GraphicsDevice[] getScreenDevices() throws HeadlessException {
        return devices.values().toArray(new CGraphicsDevice[devices.values().size()]);
    }

    public synchronized GraphicsDevice getScreenDevice(int displayID) {
        return devices.get(displayID);
    }

    @Override
    protected synchronized int getNumScreens() {
        return devices.size();
    }

    @Override
    protected GraphicsDevice makeScreenDevice(int screennum) {
        throw new UnsupportedOperationException("This method is unused and should not be called in this implementation");
    }

    @Override
    public boolean isDisplayLocal() {
       return true;
    }

    static String[] sLogicalFonts = { "Serif", "SansSerif", "Monospaced", "Dialog", "DialogInput" };

    @Override
    public Font[] getAllFonts() {

        Font[] newFonts;
        Font[] superFonts = super.getAllFonts();

        int numLogical = sLogicalFonts.length;
        int numOtherFonts = superFonts.length;

        newFonts = new Font[numOtherFonts + numLogical];
        System.arraycopy(superFonts,0,newFonts,numLogical,numOtherFonts);

        for (int i = 0; i < numLogical; i++)
        {
            newFonts[i] = new Font(sLogicalFonts[i], Font.PLAIN, 1);
        }
        return newFonts;
    }

}