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.getConstructor().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 (ReflectiveOperationException | IllegalArgumentException e) {
120 throw new Error("Could not instantiate Graphics Environment: "
121 + nm);
122 }
123 return ge;
124 }
125
126 /**
127 * Tests whether or not a display, keyboard, and mouse can be
128 * supported in this environment. If this method returns true,
129 * a HeadlessException is thrown from areas of the Toolkit
130 * and GraphicsEnvironment that are dependent on a display,
131 * keyboard, or mouse.
132 * @return {@code true} if this environment cannot support
133 * a display, keyboard, and mouse; {@code false}
134 * otherwise
135 * @see java.awt.HeadlessException
136 * @since 1.4
137 */
138 public static boolean isHeadless() {
139 return getHeadlessProperty();
140 }
141
142 /**
143 * @return warning message if headless state is assumed by default;
144 * null otherwise
145 * @since 1.5
146 */
147 static String getHeadlessMessage() {
148 if (headless == null) {
149 getHeadlessProperty(); // initialize the values
150 }
151 return defaultHeadless != Boolean.TRUE ? null :
152 "\nNo X11 DISPLAY variable was set, " +
153 "but this program performed an operation which requires it.";
154 }
155
156 /**
157 * @return the value of the property "java.awt.headless"
158 * @since 1.4
159 */
160 private static boolean getHeadlessProperty() {
161 if (headless == null) {
162 AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
163 String nm = System.getProperty("java.awt.headless");
164
165 if (nm == null) {
166 /* No need to ask for DISPLAY when run in a browser */
167 if (System.getProperty("javaplugin.version") != null) {
168 headless = defaultHeadless = Boolean.FALSE;
169 } else {
170 String osName = System.getProperty("os.name");
171 if (osName.contains("OS X") && "sun.awt.HToolkit".equals(
172 System.getProperty("awt.toolkit")))
173 {
174 headless = defaultHeadless = Boolean.TRUE;
175 } else {
176 final String display = System.getenv("DISPLAY");
177 headless = defaultHeadless =
178 ("Linux".equals(osName) ||
179 "SunOS".equals(osName) ||
180 "FreeBSD".equals(osName) ||
181 "NetBSD".equals(osName) ||
182 "OpenBSD".equals(osName) ||
183 "AIX".equals(osName)) &&
184 (display == null || display.trim().isEmpty());
185 }
186 }
187 } else {
188 headless = Boolean.valueOf(nm);
189 }
190 return null;
191 });
192 }
193 return headless;
194 }
195
196 /**
197 * Check for headless state and throw HeadlessException if headless
198 * @since 1.4
199 */
200 static void checkHeadless() throws HeadlessException {
201 if (isHeadless()) {
202 throw new HeadlessException();
203 }
204 }
205
206 /**
207 * Returns whether or not a display, keyboard, and mouse can be
208 * supported in this graphics environment. If this returns true,
209 * {@code HeadlessException} will be thrown from areas of the
210 * graphics environment that are dependent on a display, keyboard, or
211 * mouse.
212 * @return {@code true} if a display, keyboard, and mouse
213 * can be supported in this environment; {@code false}
214 * otherwise
215 * @see java.awt.HeadlessException
216 * @see #isHeadless
217 * @since 1.4
218 */
219 public boolean isHeadlessInstance() {
220 // By default (local graphics environment), simply check the
221 // headless property.
222 return getHeadlessProperty();
223 }
224
225 /**
226 * Returns an array of all of the screen {@code GraphicsDevice}
227 * objects.
228 * @return an array containing all the {@code GraphicsDevice}
229 * objects that represent screen devices
230 * @exception HeadlessException if isHeadless() returns true
231 * @see #isHeadless()
232 */
233 public abstract GraphicsDevice[] getScreenDevices()
234 throws HeadlessException;
235
236 /**
237 * Returns the default screen {@code GraphicsDevice}.
238 * @return the {@code GraphicsDevice} that represents the
239 * default screen device
240 * @exception HeadlessException if isHeadless() returns true
241 * @see #isHeadless()
242 */
243 public abstract GraphicsDevice getDefaultScreenDevice()
244 throws HeadlessException;
245
246 /**
247 * Returns a {@code Graphics2D} object for rendering into the
248 * specified {@link BufferedImage}.
249 * @param img the specified {@code BufferedImage}
250 * @return a {@code Graphics2D} to be used for rendering into
251 * the specified {@code BufferedImage}
252 * @throws NullPointerException if {@code img} is null
253 */
254 public abstract Graphics2D createGraphics(BufferedImage img);
255
256 /**
257 * Returns an array containing a one-point size instance of all fonts
258 * available in this {@code GraphicsEnvironment}. Typical usage
259 * would be to allow a user to select a particular font. Then, the
260 * application can size the font and set various font attributes by
261 * calling the {@code deriveFont} method on the chosen instance.
262 * <p>
263 * This method provides for the application the most precise control
264 * over which {@code Font} instance is used to render text.
265 * If a font in this {@code GraphicsEnvironment} has multiple
266 * programmable variations, only one
267 * instance of that {@code Font} is returned in the array, and
268 * other variations must be derived by the application.
269 * <p>
270 * If a font in this environment has multiple programmable variations,
271 * such as Multiple-Master fonts, only one instance of that font is
272 * returned in the {@code Font} array. The other variations
273 * must be derived by the application.
274 *
275 * @return an array of {@code Font} objects
276 * @see #getAvailableFontFamilyNames
277 * @see java.awt.Font
278 * @see java.awt.Font#deriveFont
279 * @see java.awt.Font#getFontName
280 * @since 1.2
281 */
282 public abstract Font[] getAllFonts();
283
284 /**
285 * Returns an array containing the names of all font families in this
286 * {@code GraphicsEnvironment} localized for the default locale,
287 * as returned by {@code Locale.getDefault()}.
288 * <p>
289 * Typical usage would be for presentation to a user for selection of
290 * a particular family name. An application can then specify this name
291 * when creating a font, in conjunction with a style, such as bold or
292 * italic, giving the font system flexibility in choosing its own best
293 * match among multiple fonts in the same font family.
294 *
295 * @return an array of {@code String} containing font family names
296 * localized for the default locale, or a suitable alternative
297 * name if no name exists for this locale.
298 * @see #getAllFonts
299 * @see java.awt.Font
300 * @see java.awt.Font#getFamily
301 * @since 1.2
302 */
303 public abstract String[] getAvailableFontFamilyNames();
304
305 /**
306 * Returns an array containing the names of all font families in this
307 * {@code GraphicsEnvironment} localized for the specified locale.
308 * <p>
309 * Typical usage would be for presentation to a user for selection of
310 * a particular family name. An application can then specify this name
311 * when creating a font, in conjunction with a style, such as bold or
312 * italic, giving the font system flexibility in choosing its own best
313 * match among multiple fonts in the same font family.
314 *
315 * @param l a {@link Locale} object that represents a
316 * particular geographical, political, or cultural region.
317 * Specifying {@code null} is equivalent to
318 * specifying {@code Locale.getDefault()}.
319 * @return an array of {@code String} containing font family names
320 * localized for the specified {@code Locale}, or a
321 * suitable alternative name if no name exists for the specified locale.
322 * @see #getAllFonts
323 * @see java.awt.Font
324 * @see java.awt.Font#getFamily
325 * @since 1.2
326 */
327 public abstract String[] getAvailableFontFamilyNames(Locale l);
328
329 /**
330 * Registers a <i>created</i> {@code Font} in this
331 * {@code GraphicsEnvironment}.
332 * A created font is one that was returned from calling
333 * {@link Font#createFont}, or derived from a created font by
334 * calling {@link Font#deriveFont}.
335 * After calling this method for such a font, it is available to
336 * be used in constructing new {@code Font}s by name or family name,
337 * and is enumerated by {@link #getAvailableFontFamilyNames} and
338 * {@link #getAllFonts} within the execution context of this
339 * application or applet. This means applets cannot register fonts in
340 * a way that they are visible to other applets.
341 * <p>
342 * Reasons that this method might not register the font and therefore
343 * return {@code false} are:
344 * <ul>
345 * <li>The font is not a <i>created</i> {@code Font}.
346 * <li>The font conflicts with a non-created {@code Font} already
347 * in this {@code GraphicsEnvironment}. For example if the name
348 * is that of a system font, or a logical font as described in the
349 * documentation of the {@link Font} class. It is implementation dependent
350 * whether a font may also conflict if it has the same family name
351 * as a system font.
352 * <p>Notice that an application can supersede the registration
353 * of an earlier created font with a new one.
354 * </ul>
355 *
356 * @param font the font to be registered
357 * @return true if the {@code font} is successfully
358 * registered in this {@code GraphicsEnvironment}.
359 * @throws NullPointerException if {@code font} is null
360 * @since 1.6
361 */
362 public boolean registerFont(Font font) {
363 if (font == null) {
364 throw new NullPointerException("font cannot be null.");
365 }
366 FontManager fm = FontManagerFactory.getInstance();
367 return fm.registerFont(font);
368 }
369
370 /**
371 * Indicates a preference for locale-specific fonts in the mapping of
372 * logical fonts to physical fonts. Calling this method indicates that font
373 * rendering should primarily use fonts specific to the primary writing
374 * system (the one indicated by the default encoding and the initial
375 * default locale). For example, if the primary writing system is
376 * Japanese, then characters should be rendered using a Japanese font
377 * if possible, and other fonts should only be used for characters for
378 * which the Japanese font doesn't have glyphs.
379 * <p>
380 * The actual change in font rendering behavior resulting from a call
381 * to this method is implementation dependent; it may have no effect at
382 * all, or the requested behavior may already match the default behavior.
383 * The behavior may differ between font rendering in lightweight
384 * and peered components. Since calling this method requests a
385 * different font, clients should expect different metrics, and may need
386 * to recalculate window sizes and layout. Therefore this method should
387 * be called before user interface initialisation.
388 * @since 1.5
389 */
390 public void preferLocaleFonts() {
391 FontManager fm = FontManagerFactory.getInstance();
392 fm.preferLocaleFonts();
393 }
394
395 /**
396 * Indicates a preference for proportional over non-proportional (e.g.
397 * dual-spaced CJK fonts) fonts in the mapping of logical fonts to
398 * physical fonts. If the default mapping contains fonts for which
399 * proportional and non-proportional variants exist, then calling
400 * this method indicates the mapping should use a proportional variant.
401 * <p>
402 * The actual change in font rendering behavior resulting from a call to
403 * this method is implementation dependent; it may have no effect at all.
404 * The behavior may differ between font rendering in lightweight and
405 * peered components. Since calling this method requests a
406 * different font, clients should expect different metrics, and may need
407 * to recalculate window sizes and layout. Therefore this method should
408 * be called before user interface initialisation.
409 * @since 1.5
410 */
411 public void preferProportionalFonts() {
412 FontManager fm = FontManagerFactory.getInstance();
413 fm.preferProportionalFonts();
414 }
415
416 /**
417 * Returns the Point where Windows should be centered.
418 * It is recommended that centered Windows be checked to ensure they fit
419 * within the available display area using getMaximumWindowBounds().
420 * @return the point where Windows should be centered
421 *
422 * @exception HeadlessException if isHeadless() returns true
423 * @see #getMaximumWindowBounds
424 * @since 1.4
425 */
426 public Point getCenterPoint() throws HeadlessException {
427 // Default implementation: return the center of the usable bounds of the
428 // default screen device.
429 Rectangle usableBounds =
430 SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());
431 return new Point((usableBounds.width / 2) + usableBounds.x,
432 (usableBounds.height / 2) + usableBounds.y);
433 }
434
435 /**
436 * Returns the maximum bounds for centered Windows.
437 * These bounds account for objects in the native windowing system such as
438 * task bars and menu bars. The returned bounds will reside on a single
439 * display with one exception: on multi-screen systems where Windows should
440 * be centered across all displays, this method returns the bounds of the
441 * entire display area.
442 * <p>
443 * To get the usable bounds of a single display, use
444 * {@code GraphicsConfiguration.getBounds()} and
445 * {@code Toolkit.getScreenInsets()}.
446 * @return the maximum bounds for centered Windows
447 *
448 * @exception HeadlessException if isHeadless() returns true
449 * @see #getCenterPoint
450 * @see GraphicsConfiguration#getBounds
451 * @see Toolkit#getScreenInsets
452 * @since 1.4
453 */
454 public Rectangle getMaximumWindowBounds() throws HeadlessException {
455 // Default implementation: return the usable bounds of the default screen
456 // device. This is correct for Microsoft Windows and non-Xinerama X11.
457 return SunGraphicsEnvironment.getUsableBounds(getDefaultScreenDevice());
458 }
459 }