/*

 * Copyright 1997-2007 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.awt;

import java.awt.image.BufferedImage;

import java.util.Locale;

import sun.java2d.HeadlessGraphicsEnvironment;

import sun.java2d.SunGraphicsEnvironment;

/**

 *

 * The <code>GraphicsEnvironment</code> class describes the collection

 * of {@link GraphicsDevice} objects and {@link java.awt.Font} objects

 * available to a Java(tm) application on a particular platform.

 * The resources in this <code>GraphicsEnvironment</code> might be local

 * or on a remote machine.  <code>GraphicsDevice</code> objects can be

 * screens, printers or image buffers and are the destination of

 * {@link Graphics2D} drawing methods.  Each <code>GraphicsDevice</code>

 * has a number of {@link GraphicsConfiguration} objects associated with

 * it.  These objects specify the different configurations in which the

 * <code>GraphicsDevice</code> can be used.

 * @see GraphicsDevice

 * @see GraphicsConfiguration

 */

public abstract class GraphicsEnvironment {

    private static GraphicsEnvironment localEnv;

    /**

     * The headless state of the Toolkit and GraphicsEnvironment

     */

    private static Boolean headless;

    /**

     * The headless state assumed by default

     */

    private static Boolean defaultHeadless;

    /**

     * This is an abstract class and cannot be instantiated directly.

     * Instances must be obtained from a suitable factory or query method.

     */

    protected GraphicsEnvironment() {

    }

    /**

     * Returns the local <code>GraphicsEnvironment</code>.

     * @return the local <code>GraphicsEnvironment</code>

     */

    public static synchronized GraphicsEnvironment getLocalGraphicsEnvironment() {

        if (localEnv == null) {

        }

        return localEnv;

    }

    /**

     * Tests whether or not a display, keyboard, and mouse can be

     * supported in this environment.  If this method returns true,

     * a HeadlessException is thrown from areas of the Toolkit

     * and GraphicsEnvironment that are dependent on a display,

     * keyboard, or mouse.

     * @return <code>true</code> if this environment cannot support

     * a display, keyboard, and mouse; <code>false</code>

     * otherwise

     * @see java.awt.HeadlessException

     * @since 1.4

     */

    public static boolean isHeadless() {

        return getHeadlessProperty();

    }

    /**

     * @return warning message if headless state is assumed by default;

     * null otherwise

     * @since 1.5

     */

    static String getHeadlessMessage() {

        if (headless == null) {

            getHeadlessProperty(); // initialize the values

        }

        return defaultHeadless != Boolean.TRUE ? null :

            "\nNo X11 DISPLAY variable was set, " +

            "but this program performed an operation which requires it.";

    }

    /**

     * @return the value of the property "java.awt.headless"

     * @since 1.4

     */

    private static boolean getHeadlessProperty() {

        if (headless == null) {

            java.security.AccessController.doPrivileged(

            new java.security.PrivilegedAction() {

                public Object run() {

                    String nm = System.getProperty("java.awt.headless");

                    if (nm == null) {

                        /* No need to ask for DISPLAY when run in a browser */

                        if (System.getProperty("javaplugin.version") != null) {

                            headless = defaultHeadless = Boolean.FALSE;

                        } else {

                            String osName = System.getProperty("os.name");

                            headless = defaultHeadless =

                                Boolean.valueOf(("Linux".equals(osName) || "SunOS".equals(osName)) &&

                                                (System.getenv("DISPLAY") == null));

                        }

                    } else if (nm.equals("true")) {

                        headless = Boolean.TRUE;

                    } else {

                        headless = Boolean.FALSE;

                    }

                    return null;

                }

                }

            );

        }

        return headless.booleanValue();

    }

    /**

     * Check for headless state and throw HeadlessException if headless

     * @since 1.4

     */

    static void checkHeadless() throws HeadlessException {

        if (isHeadless()) {

            throw new HeadlessException();

        }

    }

    /**

     * Returns whether or not a display, keyboard, and mouse can be

     * supported in this graphics environment.  If this returns true,

     * <code>HeadlessException</code> will be thrown from areas of the

     * graphics environment that are dependent on a display, keyboard, or

     * mouse.

     * @return <code>true</code> if a display, keyboard, and mouse

     * can be supported in this environment; <code>false</code>

     * otherwise

     * @see java.awt.HeadlessException

     * @see #isHeadless

     * @since 1.4

     */

    public boolean isHeadlessInstance() {

        // By default (local graphics environment), simply check the

        // headless property.

        return getHeadlessProperty();

    }

    /**

     * Returns an array of all of the screen <code>GraphicsDevice</code>

     * objects.

     * @return an array containing all the <code>GraphicsDevice</code>

     * objects that represent screen devices

     * @exception HeadlessException if isHeadless() returns true

     * @see #isHeadless()

     */

    public abstract GraphicsDevice[] getScreenDevices()

        throws HeadlessException;

    /**

     * Returns the default screen <code>GraphicsDevice</code>.

     * @return the <code>GraphicsDevice</code> that represents the

     * default screen device

     * @exception HeadlessException if isHeadless() returns true

     * @see #isHeadless()

     */

    public abstract GraphicsDevice getDefaultScreenDevice()

        throws HeadlessException;

    /**

     * Returns a <code>Graphics2D</code> object for rendering into the

     * specified {@link BufferedImage}.

     * @param img the specified <code>BufferedImage</code>

     * @return a <code>Graphics2D</code> to be used for rendering into

     * the specified <code>BufferedImage</code>

     * @throws NullPointerException if <code>img</code> is null

     */

    public abstract Graphics2D createGraphics(BufferedImage img);

    /**

     * Returns an array containing a one-point size instance of all fonts

     * available in this <code>GraphicsEnvironment</code>.  Typical usage

     * would be to allow a user to select a particular font.  Then, the

     * application can size the font and set various font attributes by

     * calling the <code>deriveFont</code> method on the choosen instance.

     * <p>

     * This method provides for the application the most precise control

     * over which <code>Font</code> instance is used to render text.

     * If a font in this <code>GraphicsEnvironment</code> has multiple

     * programmable variations, only one

     * instance of that <code>Font</code> is returned in the array, and

     * other variations must be derived by the application.

     * <p>

     * If a font in this environment has multiple programmable variations,

     * such as Multiple-Master fonts, only one instance of that font is

     * returned in the <code>Font</code> array.  The other variations

     * must be derived by the application.

     *

     * @return an array of <code>Font</code> objects

     * @see #getAvailableFontFamilyNames

     * @see java.awt.Font

     * @see java.awt.Font#deriveFont

     * @see java.awt.Font#getFontName

     * @since 1.2

     */

    public abstract Font[] getAllFonts();

    /**

     * Returns an array containing the names of all font families in this

     * <code>GraphicsEnvironment</code> localized for the default locale,

     * as returned by <code>Locale.getDefault()</code>.

     * <p>

     * Typical usage would be for presentation to a user for selection of

     * a particular family name. An application can then specify this name

     * when creating a font, in conjunction with a style, such as bold or

     * italic, giving the font system flexibility in choosing its own best

     * match among multiple fonts in the same font family.

     *

     * @return an array of <code>String</code> containing font family names

     * localized for the default locale, or a suitable alternative

     * name if no name exists for this locale.

     * @see #getAllFonts

     * @see java.awt.Font

     * @see java.awt.Font#getFamily

     * @since 1.2

     */

    public abstract String[] getAvailableFontFamilyNames();

    /**

     * Returns an array containing the names of all font families in this

     * <code>GraphicsEnvironment</code> localized for the specified locale.

     * <p>

     * Typical usage would be for presentation to a user for selection of

     * a particular family name. An application can then specify this name

     * when creating a font, in conjunction with a style, such as bold or

     * italic, giving the font system flexibility in choosing its own best

     * match among multiple fonts in the same font family.

     *

     * @param l a {@link Locale} object that represents a

     * particular geographical, political, or cultural region.

     * Specifying <code>null</code> is equivalent to

     * specifying <code>Locale.getDefault()</code>.

     * @return an array of <code>String</code> containing font family names

     * localized for the specified <code>Locale</code>, or a

     * suitable alternative name if no name exists for the specified locale.

     * @see #getAllFonts

     * @see java.awt.Font

     * @see java.awt.Font#getFamily

     * @since 1.2

     */

    public abstract String[] getAvailableFontFamilyNames(Locale l);

    /**

     * Registers a <i>created</i> <code>Font</code>in this

     * <code>GraphicsEnvironment</code>.

     * A created font is one that was returned from calling

     * {@link Font#createFont}, or derived from a created font by

     * calling {@link Font#deriveFont}.

     * After calling this method for such a font, it is available to

     * be used in constructing new <code>Font</code>s by name or family name,

     * and is enumerated by {@link #getAvailableFontFamilyNames} and

     * {@link #getAllFonts} within the execution context of this

     * application or applet. This means applets cannot register fonts in

     * a way that they are visible to other applets.

     * <p>

     * Reasons that this method might not register the font and therefore

     * return <code>false</code> are:

     * <ul>

     * <li>The font is not a <i>created</i> <code>Font</code>.

     * <li>The font conflicts with a non-created <code>Font</code> already

     * in this <code>GraphicsEnvironment</code>. For example if the name

     * is that of a system font, or a logical font as described in the

     * documentation of the {@link Font} class. It is implementation dependent

     * whether a font may also conflict if it has the same family name

     * as a system font.

     * <p>Notice that an application can supersede the registration

     * of an earlier created font with a new one.

     * </ul>

     * @return true if the <code>font</code> is successfully

     * registered in this <code>GraphicsEnvironment</code>.

     * @throws NullPointerException if <code>font</code> is null

     * @since 1.6

     */

    public boolean registerFont(Font font) {

        if (font == null) {

            throw new NullPointerException("font cannot be null.");

        }

        return sun.font.FontManager.registerFont(font);

    }

    /**

     * Indicates a preference for locale-specific fonts in the mapping of

     * logical fonts to physical fonts. Calling this method indicates that font

     * rendering should primarily use fonts specific to the primary writing

     * system (the one indicated by the default encoding and the initial

     * default locale). For example, if the primary writing system is

     * Japanese, then characters should be rendered using a Japanese font

     * if possible, and other fonts should only be used for characters for

     * which the Japanese font doesn't have glyphs.

     * <p>

     * The actual change in font rendering behavior resulting from a call

     * to this method is implementation dependent; it may have no effect at

     * all, or the requested behavior may already match the default behavior.

     * The behavior may differ between font rendering in lightweight

     * and peered components.  Since calling this method requests a

     * different font, clients should expect different metrics, and may need

     * to recalculate window sizes and layout. Therefore this method should

     * be called before user interface initialisation.

     * @since 1.5

     */

    public void preferLocaleFonts() {

        if (!(this instanceof SunGraphicsEnvironment)) {

            return;

        }

        sun.font.FontManager.preferLocaleFonts();

    }

    /**

     * Indicates a preference for proportional over non-proportional (e.g.

     * dual-spaced CJK fonts) fonts in the mapping of logical fonts to

     * physical fonts. If the default mapping contains fonts for which

     * proportional and non-proportional variants exist, then calling

     * this method indicates the mapping should use a proportional variant.

     * <p>

     * The actual change in font rendering behavior resulting from a call to

     * this method is implementation dependent; it may have no effect at all.

     * The behavior may differ between font rendering in lightweight and

     * peered components. Since calling this method requests a

     * different font, clients should expect different metrics, and may need

     * to recalculate window sizes and layout. Therefore this method should

     * be called before user interface initialisation.

     * @since 1.5

     */

    public void preferProportionalFonts() {

        if (!(this instanceof SunGraphicsEnvironment)) {

            return;

        }

        sun.font.FontManager.preferProportionalFonts();

    }

    /**

     * Returns the Point where Windows should be centered.

     * It is recommended that centered Windows be checked to ensure they fit

     * within the available display area using getMaximumWindowBounds().

     * @return the point where Windows should be centered

     *

     * @exception HeadlessException if isHeadless() returns true

     * @see #getMaximumWindowBounds

     * @since 1.4

     */

    public Point getCenterPoint() throws HeadlessException {

    // Default implementation: return the center of the usable bounds of the

    // default screen device.

        Rectangle usableBounds =

         SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());

        return new Point((usableBounds.width / 2) + usableBounds.x,

                         (usableBounds.height / 2) + usableBounds.y);

    }

    /**

     * Returns the maximum bounds for centered Windows.

     * These bounds account for objects in the native windowing system such as

     * task bars and menu bars.  The returned bounds will reside on a single

     * display with one exception: on multi-screen systems where Windows should

     * be centered across all displays, this method returns the bounds of the

     * entire display area.

     * <p>

     * To get the usable bounds of a single display, use

     * <code>GraphicsConfiguration.getBounds()</code> and

     * <code>Toolkit.getScreenInsets()</code>.

     * @return  the maximum bounds for centered Windows

     *

     * @exception HeadlessException if isHeadless() returns true

     * @see #getCenterPoint

     * @see GraphicsConfiguration#getBounds

     * @see Toolkit#getScreenInsets

     * @since 1.4

     */

    public Rectangle getMaximumWindowBounds() throws HeadlessException {

    // Default implementation: return the usable bounds of the default screen

    // device.  This is correct for Microsoft Windows and non-Xinerama X11.

        return SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());

    }

}