1 /*
2 * Copyright (c) 1997, 2014, 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.security.PrivilegedAction;
32 import java.util.Locale;
33
34 import sun.font.FontManager;
35 import sun.font.FontManagerFactory;
36 import sun.java2d.HeadlessGraphicsEnvironment;
37 import sun.java2d.SunGraphicsEnvironment;
38 import sun.security.action.GetPropertyAction;
39
40 /**
41 *
42 * The {@code GraphicsEnvironment} class describes the collection
43 * of {@link GraphicsDevice} objects and {@link java.awt.Font} objects
44 * available to a Java(tm) application on a particular platform.
45 * The resources in this {@code GraphicsEnvironment} might be local
46 * or on a remote machine. {@code GraphicsDevice} objects can be
47 * screens, printers or image buffers and are the destination of
48 * {@link Graphics2D} drawing methods. Each {@code GraphicsDevice}
49 * has a number of {@link GraphicsConfiguration} objects associated with
50 * it. These objects specify the different configurations in which the
51 * {@code GraphicsDevice} can be used.
52 * @see GraphicsDevice
53 * @see GraphicsConfiguration
54 */
55
56 public abstract class GraphicsEnvironment {
57 private static GraphicsEnvironment localEnv;
58
59 /**
60 * The headless state of the Toolkit and GraphicsEnvironment
61 */
62 private static Boolean headless;
63
64 /**
65 * The headless state assumed by default
66 */
67 private static Boolean defaultHeadless;
68
69 /**
70 * This is an abstract class and cannot be instantiated directly.
71 * Instances must be obtained from a suitable factory or query method.
72 */
73 protected GraphicsEnvironment() {
74 }
75
76 /**
77 * Returns the local {@code GraphicsEnvironment}.
78 * @return the local {@code GraphicsEnvironment}
79 */
80 public static synchronized GraphicsEnvironment getLocalGraphicsEnvironment() {
81 if (localEnv == null) {
82 localEnv = createGE();
83 }
84
85 return localEnv;
86 }
87
88 /**
89 * Creates and returns the GraphicsEnvironment, according to the
90 * system property 'java.awt.graphicsenv'.
91 *
92 * @return the graphics environment
93 */
94 private static GraphicsEnvironment createGE() {
95 GraphicsEnvironment ge;
96 String nm = AccessController.doPrivileged(new GetPropertyAction("java.awt.graphicsenv", null));
97 try {
98 // long t0 = System.currentTimeMillis();
99 Class<?> geCls;
100 try {
101 // First we try if the bootstrap class loader finds the
102 // requested class. This way we can avoid to run in a privileged
103 // block.
104 geCls = Class.forName(nm);
105 } catch (ClassNotFoundException ex) {
106 // If the bootstrap class loader fails, we try again with the
107 // application class loader.
108 ClassLoader cl = ClassLoader.getSystemClassLoader();
109 geCls = Class.forName(nm, true, cl);
110 }
111 ge = (GraphicsEnvironment)geCls.newInstance();
112 // long t1 = System.currentTimeMillis();
113 // System.out.println("GE creation took " + (t1-t0)+ "ms.");
114 if (isHeadless()) {
115 ge = new HeadlessGraphicsEnvironment(ge);
116 }
117 } catch (ClassNotFoundException e) {
118 throw new Error("Could not find class: "+nm);
119 } catch (InstantiationException e) {
120 throw new Error("Could not instantiate Graphics Environment: "
121 + nm);
122 } catch (IllegalAccessException e) {
123 throw new Error ("Could not access Graphics Environment: "
124 + nm);
125 }
126 return ge;
127 }
128
129 /**
130 * Tests whether or not a display, keyboard, and mouse can be
131 * supported in this environment. If this method returns true,
132 * a HeadlessException is thrown from areas of the Toolkit
133 * and GraphicsEnvironment that are dependent on a display,
134 * keyboard, or mouse.
135 * @return {@code true} if this environment cannot support
136 * a display, keyboard, and mouse; {@code false}
137 * otherwise
138 * @see java.awt.HeadlessException
139 * @since 1.4
140 */
141 public static boolean isHeadless() {
142 return getHeadlessProperty();
143 }
144
145 /**
146 * @return warning message if headless state is assumed by default;
147 * null otherwise
148 * @since 1.5
149 */
150 static String getHeadlessMessage() {
151 if (headless == null) {
152 getHeadlessProperty(); // initialize the values
153 }
154 return defaultHeadless != Boolean.TRUE ? null :
155 "\nNo X11 DISPLAY variable was set, " +
156 "but this program performed an operation which requires it.";
157 }
158
159 /**
160 * @return the value of the property "java.awt.headless"
161 * @since 1.4
162 */
163 private static boolean getHeadlessProperty() {
164 if (headless == null) {
165 AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
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 if (osName.contains("OS X") && "sun.awt.HToolkit".equals(
175 System.getProperty("awt.toolkit")))
176 {
177 headless = defaultHeadless = Boolean.TRUE;
178 } else {
179 final String display = System.getenv("DISPLAY");
180 headless = defaultHeadless =
181 ("Linux".equals(osName) ||
182 "SunOS".equals(osName) ||
183 "FreeBSD".equals(osName) ||
184 "NetBSD".equals(osName) ||
185 "OpenBSD".equals(osName) ||
186 "AIX".equals(osName)) &&
187 (display == null || display.trim().isEmpty());
188 }
189 }
190 } else {
191 headless = Boolean.valueOf(nm);
192 }
193 return null;
194 });
195 }
196 return headless;
197 }
198
199 /**
200 * Check for headless state and throw HeadlessException if headless
201 * @since 1.4
202 */
203 static void checkHeadless() throws HeadlessException {
204 if (isHeadless()) {
205 throw new HeadlessException();
206 }
207 }
208
209 /**
210 * Returns whether or not a display, keyboard, and mouse can be
211 * supported in this graphics environment. If this returns true,
212 * {@code HeadlessException} will be thrown from areas of the
213 * graphics environment that are dependent on a display, keyboard, or
214 * mouse.
215 * @return {@code true} if a display, keyboard, and mouse
216 * can be supported in this environment; {@code false}
217 * otherwise
218 * @see java.awt.HeadlessException
219 * @see #isHeadless
220 * @since 1.4
221 */
222 public boolean isHeadlessInstance() {
223 // By default (local graphics environment), simply check the
224 // headless property.
225 return getHeadlessProperty();
226 }
227
228 /**
229 * Returns an array of all of the screen {@code GraphicsDevice}
230 * objects.
231 * @return an array containing all the {@code GraphicsDevice}
232 * objects that represent screen devices
233 * @exception HeadlessException if isHeadless() returns true
234 * @see #isHeadless()
235 */
236 public abstract GraphicsDevice[] getScreenDevices()
237 throws HeadlessException;
238
239 /**
240 * Returns the default screen {@code GraphicsDevice}.
241 * @return the {@code GraphicsDevice} that represents the
242 * default screen device
243 * @exception HeadlessException if isHeadless() returns true
244 * @see #isHeadless()
245 */
246 public abstract GraphicsDevice getDefaultScreenDevice()
247 throws HeadlessException;
248
249 /**
250 * Returns a {@code Graphics2D} object for rendering into the
251 * specified {@link BufferedImage}.
252 * @param img the specified {@code BufferedImage}
253 * @return a {@code Graphics2D} to be used for rendering into
254 * the specified {@code BufferedImage}
255 * @throws NullPointerException if {@code img} is null
256 */
257 public abstract Graphics2D createGraphics(BufferedImage img);
258
259 /**
260 * Returns an array containing a one-point size instance of all fonts
261 * available in this {@code GraphicsEnvironment}. Typical usage
262 * would be to allow a user to select a particular font. Then, the
263 * application can size the font and set various font attributes by
264 * calling the {@code deriveFont} method on the chosen instance.
265 * <p>
266 * This method provides for the application the most precise control
267 * over which {@code Font} instance is used to render text.
268 * If a font in this {@code GraphicsEnvironment} has multiple
269 * programmable variations, only one
270 * instance of that {@code Font} is returned in the array, and
271 * other variations must be derived by the application.
272 * <p>
273 * If a font in this environment has multiple programmable variations,
274 * such as Multiple-Master fonts, only one instance of that font is
275 * returned in the {@code Font} array. The other variations
276 * must be derived by the application.
277 *
278 * @return an array of {@code Font} objects
279 * @see #getAvailableFontFamilyNames
280 * @see java.awt.Font
281 * @see java.awt.Font#deriveFont
282 * @see java.awt.Font#getFontName
283 * @since 1.2
284 */
285 public abstract Font[] getAllFonts();
286
287 /**
288 * Returns an array containing the names of all font families in this
289 * {@code GraphicsEnvironment} localized for the default locale,
290 * as returned by {@code Locale.getDefault()}.
291 * <p>
292 * Typical usage would be for presentation to a user for selection of
293 * a particular family name. An application can then specify this name
294 * when creating a font, in conjunction with a style, such as bold or
295 * italic, giving the font system flexibility in choosing its own best
296 * match among multiple fonts in the same font family.
297 *
298 * @return an array of {@code String} containing font family names
299 * localized for the default locale, or a suitable alternative
300 * name if no name exists for this locale.
301 * @see #getAllFonts
302 * @see java.awt.Font
303 * @see java.awt.Font#getFamily
304 * @since 1.2
305 */
306 public abstract String[] getAvailableFontFamilyNames();
307
308 /**
309 * Returns an array containing the names of all font families in this
310 * {@code GraphicsEnvironment} localized for the specified locale.
311 * <p>
312 * Typical usage would be for presentation to a user for selection of
313 * a particular family name. An application can then specify this name
314 * when creating a font, in conjunction with a style, such as bold or
315 * italic, giving the font system flexibility in choosing its own best
316 * match among multiple fonts in the same font family.
317 *
318 * @param l a {@link Locale} object that represents a
319 * particular geographical, political, or cultural region.
320 * Specifying {@code null} is equivalent to
321 * specifying {@code Locale.getDefault()}.
322 * @return an array of {@code String} containing font family names
323 * localized for the specified {@code Locale}, or a
324 * suitable alternative name if no name exists for the specified locale.
325 * @see #getAllFonts
326 * @see java.awt.Font
327 * @see java.awt.Font#getFamily
328 * @since 1.2
329 */
330 public abstract String[] getAvailableFontFamilyNames(Locale l);
331
332 /**
333 * Registers a <i>created</i> {@code Font} in this
334 * {@code GraphicsEnvironment}.
335 * A created font is one that was returned from calling
336 * {@link Font#createFont}, or derived from a created font by
337 * calling {@link Font#deriveFont}.
338 * After calling this method for such a font, it is available to
339 * be used in constructing new {@code Font}s by name or family name,
340 * and is enumerated by {@link #getAvailableFontFamilyNames} and
341 * {@link #getAllFonts} within the execution context of this
342 * application or applet. This means applets cannot register fonts in
343 * a way that they are visible to other applets.
344 * <p>
345 * Reasons that this method might not register the font and therefore
346 * return {@code false} are:
347 * <ul>
348 * <li>The font is not a <i>created</i> {@code Font}.
349 * <li>The font conflicts with a non-created {@code Font} already
350 * in this {@code GraphicsEnvironment}. For example if the name
351 * is that of a system font, or a logical font as described in the
352 * documentation of the {@link Font} class. It is implementation dependent
353 * whether a font may also conflict if it has the same family name
354 * as a system font.
355 * <p>Notice that an application can supersede the registration
356 * of an earlier created font with a new one.
357 * </ul>
358 *
359 * @param font the font to be registered
360 * @return true if the {@code font} is successfully
361 * registered in this {@code GraphicsEnvironment}.
362 * @throws NullPointerException if {@code font} is null
363 * @since 1.6
364 */
365 public boolean registerFont(Font font) {
366 if (font == null) {
367 throw new NullPointerException("font cannot be null.");
368 }
369 FontManager fm = FontManagerFactory.getInstance();
370 return fm.registerFont(font);
371 }
372
373 /**
374 * Indicates a preference for locale-specific fonts in the mapping of
375 * logical fonts to physical fonts. Calling this method indicates that font
376 * rendering should primarily use fonts specific to the primary writing
377 * system (the one indicated by the default encoding and the initial
378 * default locale). For example, if the primary writing system is
379 * Japanese, then characters should be rendered using a Japanese font
380 * if possible, and other fonts should only be used for characters for
381 * which the Japanese font doesn't have glyphs.
382 * <p>
383 * The actual change in font rendering behavior resulting from a call
384 * to this method is implementation dependent; it may have no effect at
385 * all, or the requested behavior may already match the default behavior.
386 * The behavior may differ between font rendering in lightweight
387 * and peered components. Since calling this method requests a
388 * different font, clients should expect different metrics, and may need
389 * to recalculate window sizes and layout. Therefore this method should
390 * be called before user interface initialisation.
391 * @since 1.5
392 */
393 public void preferLocaleFonts() {
394 FontManager fm = FontManagerFactory.getInstance();
395 fm.preferLocaleFonts();
396 }
397
398 /**
399 * Indicates a preference for proportional over non-proportional (e.g.
400 * dual-spaced CJK fonts) fonts in the mapping of logical fonts to
401 * physical fonts. If the default mapping contains fonts for which
402 * proportional and non-proportional variants exist, then calling
403 * this method indicates the mapping should use a proportional variant.
404 * <p>
405 * The actual change in font rendering behavior resulting from a call to
406 * this method is implementation dependent; it may have no effect at all.
407 * The behavior may differ between font rendering in lightweight and
408 * peered components. Since calling this method requests a
409 * different font, clients should expect different metrics, and may need
410 * to recalculate window sizes and layout. Therefore this method should
411 * be called before user interface initialisation.
412 * @since 1.5
413 */
414 public void preferProportionalFonts() {
415 FontManager fm = FontManagerFactory.getInstance();
416 fm.preferProportionalFonts();
417 }
418
419 /**
420 * Returns the Point where Windows should be centered.
421 * It is recommended that centered Windows be checked to ensure they fit
422 * within the available display area using getMaximumWindowBounds().
423 * @return the point where Windows should be centered
424 *
425 * @exception HeadlessException if isHeadless() returns true
426 * @see #getMaximumWindowBounds
427 * @since 1.4
428 */
429 public Point getCenterPoint() throws HeadlessException {
430 // Default implementation: return the center of the usable bounds of the
431 // default screen device.
432 Rectangle usableBounds =
433 SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());
434 return new Point((usableBounds.width / 2) + usableBounds.x,
435 (usableBounds.height / 2) + usableBounds.y);
436 }
437
438 /**
439 * Returns the maximum bounds for centered Windows.
440 * These bounds account for objects in the native windowing system such as
441 * task bars and menu bars. The returned bounds will reside on a single
442 * display with one exception: on multi-screen systems where Windows should
443 * be centered across all displays, this method returns the bounds of the
444 * entire display area.
445 * <p>
446 * To get the usable bounds of a single display, use
447 * {@code GraphicsConfiguration.getBounds()} and
448 * {@code Toolkit.getScreenInsets()}.
449 * @return the maximum bounds for centered Windows
450 *
451 * @exception HeadlessException if isHeadless() returns true
452 * @see #getCenterPoint
453 * @see GraphicsConfiguration#getBounds
454 * @see Toolkit#getScreenInsets
455 * @since 1.4
456 */
457 public Rectangle getMaximumWindowBounds() throws HeadlessException {
458 // Default implementation: return the usable bounds of the default screen
459 // device. This is correct for Microsoft Windows and non-Xinerama X11.
460 return SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());
461 }
462 }