libjava/java/awt/GraphicsEnvironment.java

   1 /* GraphicsEnvironment.java -- information about the graphics environment
   2    Copyright (C) 2002 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.awt;
  40
  41 import java.awt.image.BufferedImage;
  42 import java.util.Locale;
  43
  44 /**
  45  * This descibes the collection of GraphicsDevice and Font objects available
  46  * on a given platform. The resources might be local or remote, and specify
  47  * the valid configurations for displaying graphics.
  48  *
  49  * @author Eric Blake <ebb9@email.byu.edu>
  50  * @see GraphicsDevice
  51  * @see GraphicsConfiguration
  52  * @since 1.4
  53  * @status updated to 1.4
  54  */
  55 public abstract class GraphicsEnvironment
  56 {
  57   /**
  58    * The environment must be obtained from a factory or query method, hence
  59    * this constructor is protected.
  60    */
  61   protected GraphicsEnvironment()
  62   {
  63   }
  64
  65   /**
  66    * Returns the local graphics environment.
  67    *
  68    * XXX Not implemented in Classpath yet.
  69    * @return the local environment
  70    */
  71   public static GraphicsEnvironment getLocalGraphicsEnvironment()
  72   {
  73     throw new Error("not implemented");
  74   }
  75
  76   /**
  77    * Check if the local environment is headless, meaning that it does not
  78    * support a display, keyboard, or mouse. Many methods in the Abstract
  79    * Windows Toolkit (java.awt) throw a {@link HeadlessException} if this
  80    * returns true.
  81    *
  82    * XXX For now, Classpath assumes that it is never headless.
  83    *
  84    * @return true if the environment is headless, meaning that graphics are
  85    *         unsupported
  86    * @since 1.4
  87    */
  88   public static boolean isHeadless()
  89   {
  90     // XXX Should be: getLocalGraphicsEnvironment().isHeadlessInstance();
  91     return false;
  92   }
  93
  94   /**
  95    * Check if the given environment is headless, meaning that it does not
  96    * support a display, keyboard, or mouse. Many methods in the Abstract
  97    * Windows Toolkit (java.awt) throw a {@link HeadlessException} if this
  98    * returns true. This default implementation returns false, so subclasses
  99    * need only override it if they are headless.
 100    *
 101    * @return true if the environment is headless, meaning that graphics are
 102    *         unsupported
 103    * @since 1.4
 104    */
 105   public boolean isHeadlessInstance()
 106   {
 107     return false;
 108   }
 109
 110   /**
 111    * Get an array of all the GraphicsDevice objects.
 112    *
 113    * @return the available graphics devices, may be 0 length
 114    * @throws HeadlessException if the environment is headless
 115    */
 116   public abstract GraphicsDevice[] getScreenDevices();
 117
 118   /**
 119    * Get the default screen GraphicsDevice object.
 120    *
 121    * @return the default screen device
 122    * @throws HeadlessException if the environment is headless
 123    */
 124   public abstract GraphicsDevice getDefaultScreenDevice();
 125
 126   /**
 127    * Return a Graphics2D object which will render into the specified image.
 128    *
 129    * @param image the image to render into
 130    * @return the object that renders into the image
 131    */
 132   public abstract Graphics2D createGraphics(BufferedImage image);
 133
 134   /**
 135    * Returns an array of the one-point size fonts available in this
 136    * environment. From there, the user can select the font and derive the
 137    * correct one of proper size and attributes, using <code>deriveFont</code>.
 138    * Only one master version of each font appears in this array; if a font
 139    * can be derived from another, it must be created in that way.
 140    *
 141    * @return the array of available fonts
 142    * @see #getAvailableFontFamilyNames()
 143    * @see Font#deriveFont(int, float)
 144    * @since 1.2
 145    */
 146   public abstract Font[] getAllFonts();
 147
 148   /**
 149    * Returns an array of the font family names available in this environment.
 150    * This allows flexibility in choosing the style of font, while still letting
 151    * the Font class decide its best match.
 152    *
 153    * @return the array of available font families
 154    * @see #getAllFonts()
 155    * @see Font#getFamily()
 156    * @since 1.2
 157    */
 158   public abstract String[] getAvailableFontFamilyNames();
 159
 160   /**
 161    * Returns an array of the font family names available in this environment,
 162    * localized to the current Locale if l is non-null. This allows
 163    * flexibility in choosing the style of font, while still letting the Font
 164    * class decide its best match.
 165    *
 166    * @param l the locale to use
 167    * @return the array of available font families, localized
 168    * @see #getAllFonts()
 169    * @see Font#getFamily()
 170    * @since 1.2
 171    */
 172   public abstract String[] getAvailableFontFamilyNames(Locale l);
 173
 174   /**
 175    * Returns the point where a window should be centered. You should probably
 176    * also check that the window fits within the screen bounds. The default
 177    * simply returns the center of the maximum window bounds; subclasses should
 178    * override this if native objects (like scrollbars) make that off-centered.
 179    *
 180    * @return the centering point
 181    * @throws HeadlessException if the environment is headless
 182    * @see #getMaximumWindowBounds()
 183    * @since 1.4
 184    */
 185   public Point getCenterPoint()
 186   {
 187     Rectangle r = getMaximumWindowBounds();
 188     return new Point(r.x + r.width / 2, r.y + r.height / 2);
 189   }
 190
 191   /**
 192    * Returns the maximum bounds for a centered window object. The default
 193    * implementation simply returns the bounds of the default configuration
 194    * of the default screen; subclasses should override this to if native
 195    * objects (like scrollbars) reduce what is truly available. Also,
 196    * subclasses should override this if the window should be centered across
 197    * a multi-screen display.
 198    *
 199    * @return the maximum window bounds
 200    * @throws HeadlessException if the environment is headless
 201    * @see #getCenterPoint()
 202    * @see GraphicsConfiguration#getBounds()
 203    * @see Toolkit#getScreenInsets(GraphicsConfiguration)
 204    * @since 1.4
 205    */
 206   public Rectangle getMaximumWindowBounds()
 207   {
 208     return getDefaultScreenDevice().getDefaultConfiguration().getBounds();
 209   }
 210 } // class GraphicsEnvironment