1 /*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26
27 package java.awt;
28
29 import java.awt.image.BufferedImage;
30 import java.security.AccessController;
31 import java.util.Locale;
32
33 import sun.font.FontManager;
34 import sun.font.FontManagerFactory;
35 import sun.java2d.HeadlessGraphicsEnvironment;
36 import sun.java2d.SunGraphicsEnvironment;
37 import sun.security.action.GetPropertyAction;
38
39 /**
40 *
41 * The <code>GraphicsEnvironment</code> class describes the collection
42 * of {@link GraphicsDevice} objects and {@link java.awt.Font} objects
43 * available to a Java(tm) application on a particular platform.
44 * The resources in this <code>GraphicsEnvironment</code> might be local
45 * or on a remote machine. <code>GraphicsDevice</code> objects can be
46 * screens, printers or image buffers and are the destination of
47 * {@link Graphics2D} drawing methods. Each <code>GraphicsDevice</code>
48 * has a number of {@link GraphicsConfiguration} objects associated with
49 * it. These objects specify the different configurations in which the
50 * <code>GraphicsDevice</code> can be used.
51 * @see GraphicsDevice
52 * @see GraphicsConfiguration
53 */
54
55 public abstract class GraphicsEnvironment {
56 private static GraphicsEnvironment localEnv;
57
58 /**
59 * The headless state of the Toolkit and GraphicsEnvironment
60 */
61 private static Boolean headless;
62
63 /**
64 * The headless state assumed by default
65 */
66 private static Boolean defaultHeadless;
67
68 /**
69 * This is an abstract class and cannot be instantiated directly.
70 * Instances must be obtained from a suitable factory or query method.
71 */
72 protected GraphicsEnvironment() {
73 }
74
75 /**
76 * Returns the local <code>GraphicsEnvironment</code>.
77 * @return the local <code>GraphicsEnvironment</code>
78 */
79 public static synchronized GraphicsEnvironment getLocalGraphicsEnvironment() {
80 if (localEnv == null) {
81 localEnv = createGE();
82 }
83
84 return localEnv;
85 }
86
87 /**
88 * Creates and returns the GraphicsEnvironment, according to the
89 * system property 'java.awt.graphicsenv'.
90 *
91 * @return the graphics environment
92 */
93 private static GraphicsEnvironment createGE() {
94 GraphicsEnvironment ge;
95 String nm = AccessController.doPrivileged(new GetPropertyAction("java.awt.graphicsenv", null));
96 try {
97 // long t0 = System.currentTimeMillis();
98 Class geCls;
99 try {
100 // First we try if the bootclassloader finds the requested
101 // class. This way we can avoid to run in a privileged block.
102 geCls = Class.forName(nm);
103 } catch (ClassNotFoundException ex) {
104 // If the bootclassloader fails, we try again with the
105 // application classloader.
106 ClassLoader cl = ClassLoader.getSystemClassLoader();
107 geCls = Class.forName(nm, true, cl);
108 }
109 ge = (GraphicsEnvironment) geCls.newInstance();
110 // long t1 = System.currentTimeMillis();
111 // System.out.println("GE creation took " + (t1-t0)+ "ms.");
112 if (isHeadless()) {
113 ge = new HeadlessGraphicsEnvironment(ge);
114 }
115 } catch (ClassNotFoundException e) {
116 throw new Error("Could not find class: "+nm);
117 } catch (InstantiationException e) {
118 throw new Error("Could not instantiate Graphics Environment: "
119 + nm);
120 } catch (IllegalAccessException e) {
121 throw new Error ("Could not access Graphics Environment: "
122 + nm);
123 }
124 return ge;
125 }
126
127 /**
128 * Tests whether or not a display, keyboard, and mouse can be
129 * supported in this environment. If this method returns true,
130 * a HeadlessException is thrown from areas of the Toolkit
131 * and GraphicsEnvironment that are dependent on a display,
132 * keyboard, or mouse.
133 * @return <code>true</code> if this environment cannot support
134 * a display, keyboard, and mouse; <code>false</code>
135 * otherwise
136 * @see java.awt.HeadlessException
137 * @since 1.4
138 */
139 public static boolean isHeadless() {
140 return getHeadlessProperty();
141 }
142
143 /**
144 * @return warning message if headless state is assumed by default;
145 * null otherwise
146 * @since 1.5
147 */
148 static String getHeadlessMessage() {
149 if (headless == null) {
150 getHeadlessProperty(); // initialize the values
151 }
152 return defaultHeadless != Boolean.TRUE ? null :
153 "\nNo X11 DISPLAY variable was set, " +
154 "but this program performed an operation which requires it.";
155 }
156
157 /**
158 * @return the value of the property "java.awt.headless"
159 * @since 1.4
160 */
161 private static boolean getHeadlessProperty() {
162 if (headless == null) {
163 java.security.AccessController.doPrivileged(
164 new java.security.PrivilegedAction() {
165 public Object run() {
166 String nm = System.getProperty("java.awt.headless");
167
168 if (nm == null) {
169 /* No need to ask for DISPLAY when run in a browser */
170 if (System.getProperty("javaplugin.version") != null) {
171 headless = defaultHeadless = Boolean.FALSE;
172 } else {
173 String osName = System.getProperty("os.name");
174 headless = defaultHeadless =
175 Boolean.valueOf(("Linux".equals(osName) || "SunOS".equals(osName)) &&
176 (System.getenv("DISPLAY") == null));
177 }
178 } else if (nm.equals("true")) {
179 headless = Boolean.TRUE;
180 } else {
181 headless = Boolean.FALSE;
182 }
183 return null;
184 }
185 }
186 );
187 }
188 return headless.booleanValue();
189 }
190
191 /**
192 * Check for headless state and throw HeadlessException if headless
193 * @since 1.4
194 */
195 static void checkHeadless() throws HeadlessException {
196 if (isHeadless()) {
197 throw new HeadlessException();
198 }
199 }
200
201 /**
202 * Returns whether or not a display, keyboard, and mouse can be
203 * supported in this graphics environment. If this returns true,
204 * <code>HeadlessException</code> will be thrown from areas of the
205 * graphics environment that are dependent on a display, keyboard, or
206 * mouse.
207 * @return <code>true</code> if a display, keyboard, and mouse
208 * can be supported in this environment; <code>false</code>
209 * otherwise
210 * @see java.awt.HeadlessException
211 * @see #isHeadless
212 * @since 1.4
213 */
214 public boolean isHeadlessInstance() {
215 // By default (local graphics environment), simply check the
216 // headless property.
217 return getHeadlessProperty();
218 }
219
220 /**
221 * Returns an array of all of the screen <code>GraphicsDevice</code>
222 * objects.
223 * @return an array containing all the <code>GraphicsDevice</code>
224 * objects that represent screen devices
225 * @exception HeadlessException if isHeadless() returns true
226 * @see #isHeadless()
227 */
228 public abstract GraphicsDevice[] getScreenDevices()
229 throws HeadlessException;
230
231 /**
232 * Returns the default screen <code>GraphicsDevice</code>.
233 * @return the <code>GraphicsDevice</code> that represents the
234 * default screen device
235 * @exception HeadlessException if isHeadless() returns true
236 * @see #isHeadless()
237 */
238 public abstract GraphicsDevice getDefaultScreenDevice()
239 throws HeadlessException;
240
241 /**
242 * Returns a <code>Graphics2D</code> object for rendering into the
243 * specified {@link BufferedImage}.
244 * @param img the specified <code>BufferedImage</code>
245 * @return a <code>Graphics2D</code> to be used for rendering into
246 * the specified <code>BufferedImage</code>
247 * @throws NullPointerException if <code>img</code> is null
248 */
249 public abstract Graphics2D createGraphics(BufferedImage img);
250
251 /**
252 * Returns an array containing a one-point size instance of all fonts
253 * available in this <code>GraphicsEnvironment</code>. Typical usage
254 * would be to allow a user to select a particular font. Then, the
255 * application can size the font and set various font attributes by
256 * calling the <code>deriveFont</code> method on the choosen instance.
257 * <p>
258 * This method provides for the application the most precise control
259 * over which <code>Font</code> instance is used to render text.
260 * If a font in this <code>GraphicsEnvironment</code> has multiple
261 * programmable variations, only one
262 * instance of that <code>Font</code> is returned in the array, and
263 * other variations must be derived by the application.
264 * <p>
265 * If a font in this environment has multiple programmable variations,
266 * such as Multiple-Master fonts, only one instance of that font is
267 * returned in the <code>Font</code> array. The other variations
268 * must be derived by the application.
269 *
270 * @return an array of <code>Font</code> objects
271 * @see #getAvailableFontFamilyNames
272 * @see java.awt.Font
273 * @see java.awt.Font#deriveFont
274 * @see java.awt.Font#getFontName
275 * @since 1.2
276 */
277 public abstract Font[] getAllFonts();
278
279 /**
280 * Returns an array containing the names of all font families in this
281 * <code>GraphicsEnvironment</code> localized for the default locale,
282 * as returned by <code>Locale.getDefault()</code>.
283 * <p>
284 * Typical usage would be for presentation to a user for selection of
285 * a particular family name. An application can then specify this name
286 * when creating a font, in conjunction with a style, such as bold or
287 * italic, giving the font system flexibility in choosing its own best
288 * match among multiple fonts in the same font family.
289 *
290 * @return an array of <code>String</code> containing font family names
291 * localized for the default locale, or a suitable alternative
292 * name if no name exists for this locale.
293 * @see #getAllFonts
294 * @see java.awt.Font
295 * @see java.awt.Font#getFamily
296 * @since 1.2
297 */
298 public abstract String[] getAvailableFontFamilyNames();
299
300 /**
301 * Returns an array containing the names of all font families in this
302 * <code>GraphicsEnvironment</code> localized for the specified locale.
303 * <p>
304 * Typical usage would be for presentation to a user for selection of
305 * a particular family name. An application can then specify this name
306 * when creating a font, in conjunction with a style, such as bold or
307 * italic, giving the font system flexibility in choosing its own best
308 * match among multiple fonts in the same font family.
309 *
310 * @param l a {@link Locale} object that represents a
311 * particular geographical, political, or cultural region.
312 * Specifying <code>null</code> is equivalent to
313 * specifying <code>Locale.getDefault()</code>.
314 * @return an array of <code>String</code> containing font family names
315 * localized for the specified <code>Locale</code>, or a
316 * suitable alternative name if no name exists for the specified locale.
317 * @see #getAllFonts
318 * @see java.awt.Font
319 * @see java.awt.Font#getFamily
320 * @since 1.2
321 */
322 public abstract String[] getAvailableFontFamilyNames(Locale l);
323
324 /**
325 * Registers a <i>created</i> <code>Font</code>in this
326 * <code>GraphicsEnvironment</code>.
327 * A created font is one that was returned from calling
328 * {@link Font#createFont}, or derived from a created font by
329 * calling {@link Font#deriveFont}.
330 * After calling this method for such a font, it is available to
331 * be used in constructing new <code>Font</code>s by name or family name,
332 * and is enumerated by {@link #getAvailableFontFamilyNames} and
333 * {@link #getAllFonts} within the execution context of this
334 * application or applet. This means applets cannot register fonts in
335 * a way that they are visible to other applets.
336 * <p>
337 * Reasons that this method might not register the font and therefore
338 * return <code>false</code> are:
339 * <ul>
340 * <li>The font is not a <i>created</i> <code>Font</code>.
341 * <li>The font conflicts with a non-created <code>Font</code> already
342 * in this <code>GraphicsEnvironment</code>. For example if the name
343 * is that of a system font, or a logical font as described in the
344 * documentation of the {@link Font} class. It is implementation dependent
345 * whether a font may also conflict if it has the same family name
346 * as a system font.
347 * <p>Notice that an application can supersede the registration
348 * of an earlier created font with a new one.
349 * </ul>
350 * @return true if the <code>font</code> is successfully
351 * registered in this <code>GraphicsEnvironment</code>.
352 * @throws NullPointerException if <code>font</code> is null
353 * @since 1.6
354 */
355 public boolean registerFont(Font font) {
356 if (font == null) {
357 throw new NullPointerException("font cannot be null.");
358 }
359 FontManager fm = FontManagerFactory.getInstance();
360 return fm.registerFont(font);
361 }
362
363 /**
364 * Indicates a preference for locale-specific fonts in the mapping of
365 * logical fonts to physical fonts. Calling this method indicates that font
366 * rendering should primarily use fonts specific to the primary writing
367 * system (the one indicated by the default encoding and the initial
368 * default locale). For example, if the primary writing system is
369 * Japanese, then characters should be rendered using a Japanese font
370 * if possible, and other fonts should only be used for characters for
371 * which the Japanese font doesn't have glyphs.
372 * <p>
373 * The actual change in font rendering behavior resulting from a call
374 * to this method is implementation dependent; it may have no effect at
375 * all, or the requested behavior may already match the default behavior.
376 * The behavior may differ between font rendering in lightweight
377 * and peered components. Since calling this method requests a
378 * different font, clients should expect different metrics, and may need
379 * to recalculate window sizes and layout. Therefore this method should
380 * be called before user interface initialisation.
381 * @since 1.5
382 */
383 public void preferLocaleFonts() {
384 FontManager fm = FontManagerFactory.getInstance();
385 fm.preferLocaleFonts();
386 }
387
388 /**
389 * Indicates a preference for proportional over non-proportional (e.g.
390 * dual-spaced CJK fonts) fonts in the mapping of logical fonts to
391 * physical fonts. If the default mapping contains fonts for which
392 * proportional and non-proportional variants exist, then calling
393 * this method indicates the mapping should use a proportional variant.
394 * <p>
395 * The actual change in font rendering behavior resulting from a call to
396 * this method is implementation dependent; it may have no effect at all.
397 * The behavior may differ between font rendering in lightweight and
398 * peered components. Since calling this method requests a
399 * different font, clients should expect different metrics, and may need
400 * to recalculate window sizes and layout. Therefore this method should
401 * be called before user interface initialisation.
402 * @since 1.5
403 */
404 public void preferProportionalFonts() {
405 FontManager fm = FontManagerFactory.getInstance();
406 fm.preferProportionalFonts();
407 }
408
409 /**
410 * Returns the Point where Windows should be centered.
411 * It is recommended that centered Windows be checked to ensure they fit
412 * within the available display area using getMaximumWindowBounds().
413 * @return the point where Windows should be centered
414 *
415 * @exception HeadlessException if isHeadless() returns true
416 * @see #getMaximumWindowBounds
417 * @since 1.4
418 */
419 public Point getCenterPoint() throws HeadlessException {
420 // Default implementation: return the center of the usable bounds of the
421 // default screen device.
422 Rectangle usableBounds =
423 SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());
424 return new Point((usableBounds.width / 2) + usableBounds.x,
425 (usableBounds.height / 2) + usableBounds.y);
426 }
427
428 /**
429 * Returns the maximum bounds for centered Windows.
430 * These bounds account for objects in the native windowing system such as
431 * task bars and menu bars. The returned bounds will reside on a single
432 * display with one exception: on multi-screen systems where Windows should
433 * be centered across all displays, this method returns the bounds of the
434 * entire display area.
435 * <p>
436 * To get the usable bounds of a single display, use
437 * <code>GraphicsConfiguration.getBounds()</code> and
438 * <code>Toolkit.getScreenInsets()</code>.
439 * @return the maximum bounds for centered Windows
440 *
441 * @exception HeadlessException if isHeadless() returns true
442 * @see #getCenterPoint
443 * @see GraphicsConfiguration#getBounds
444 * @see Toolkit#getScreenInsets
445 * @since 1.4
446 */
447 public Rectangle getMaximumWindowBounds() throws HeadlessException {
448 // Default implementation: return the usable bounds of the default screen
449 // device. This is correct for Microsoft Windows and non-Xinerama X11.
450 return SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());
451 }
452 }