1 /*
2 * Copyright 1998-2006 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 /*
27 * @author Charlton Innovations, Inc.
28 */
29
30 package java.awt.font;
31
32 import java.awt.RenderingHints;
33 import static java.awt.RenderingHints.*;
34 import java.awt.geom.AffineTransform;
35
36 /**
37 * The <code>FontRenderContext</code> class is a container for the
38 * information needed to correctly measure text. The measurement of text
39 * can vary because of rules that map outlines to pixels, and rendering
40 * hints provided by an application.
41 * <p>
42 * One such piece of information is a transform that scales
43 * typographical points to pixels. (A point is defined to be exactly 1/72
44 * of an inch, which is slightly different than
45 * the traditional mechanical measurement of a point.) A character that
46 * is rendered at 12pt on a 600dpi device might have a different size
47 * than the same character rendered at 12pt on a 72dpi device because of
48 * such factors as rounding to pixel boundaries and hints that the font
49 * designer may have specified.
50 * <p>
51 * Anti-aliasing and Fractional-metrics specified by an application can also
52 * affect the size of a character because of rounding to pixel
53 * boundaries.
54 * <p>
55 * Typically, instances of <code>FontRenderContext</code> are
56 * obtained from a {@link java.awt.Graphics2D Graphics2D} object. A
57 * <code>FontRenderContext</code> which is directly constructed will
58 * most likely not represent any actual graphics device, and may lead
59 * to unexpected or incorrect results.
60 * <p>
61 * @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING
62 * @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS
63 * @see java.awt.Graphics2D#getFontRenderContext()
64 * @see java.awt.font.LineMetrics
65 */
66
67 public class FontRenderContext {
68 private transient AffineTransform tx;
69 private transient Object aaHintValue;
70 private transient Object fmHintValue;
71 private transient boolean defaulting;
72
73 /**
74 * Constructs a new <code>FontRenderContext</code>
75 * object.
76 *
77 */
78 protected FontRenderContext() {
79 aaHintValue = VALUE_TEXT_ANTIALIAS_DEFAULT;
80 fmHintValue = VALUE_FRACTIONALMETRICS_DEFAULT;
81 defaulting = true;
82 }
83
84 /**
85 * Constructs a <code>FontRenderContext</code> object from an
86 * optional {@link AffineTransform} and two <code>boolean</code>
87 * values that determine if the newly constructed object has
88 * anti-aliasing or fractional metrics.
89 * In each case the boolean values <CODE>true</CODE> and <CODE>false</CODE>
90 * correspond to the rendering hint values <CODE>ON</CODE> and
91 * <CODE>OFF</CODE> respectively.
92 * <p>
93 * To specify other hint values, use the constructor which
94 * specifies the rendering hint values as parameters :
95 * {@link #FontRenderContext(AffineTransform, Object, Object)}.
96 * @param tx the transform which is used to scale typographical points
97 * to pixels in this <code>FontRenderContext</code>. If null, an
98 * identity transform is used.
99 * @param isAntiAliased determines if the newly constructed object
100 * has anti-aliasing.
101 * @param usesFractionalMetrics determines if the newly constructed
102 * object has fractional metrics.
103 */
104 public FontRenderContext(AffineTransform tx,
105 boolean isAntiAliased,
106 boolean usesFractionalMetrics) {
107 if (tx != null && !tx.isIdentity()) {
108 this.tx = new AffineTransform(tx);
109 }
110 if (isAntiAliased) {
111 aaHintValue = VALUE_TEXT_ANTIALIAS_ON;
112 } else {
113 aaHintValue = VALUE_TEXT_ANTIALIAS_OFF;
114 }
115 if (usesFractionalMetrics) {
116 fmHintValue = VALUE_FRACTIONALMETRICS_ON;
117 } else {
118 fmHintValue = VALUE_FRACTIONALMETRICS_OFF;
119 }
120 }
121
122 /**
123 * Constructs a <code>FontRenderContext</code> object from an
124 * optional {@link AffineTransform} and two <code>Object</code>
125 * values that determine if the newly constructed object has
126 * anti-aliasing or fractional metrics.
127 * @param tx the transform which is used to scale typographical points
128 * to pixels in this <code>FontRenderContext</code>. If null, an
129 * identity tranform is used.
130 * @param aaHint - one of the text antialiasing rendering hint values
131 * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
132 * Any other value will throw <code>IllegalArgumentException</code>.
133 * {@link java.awt.RenderingHints#VALUE_TEXT_ANTIALIAS_DEFAULT VALUE_TEXT_ANTIALIAS_DEFAULT}
134 * may be specified, in which case the mode used is implementation
135 * dependent.
136 * @param fmHint - one of the text fractional rendering hint values defined
137 * in {@link java.awt.RenderingHints java.awt.RenderingHints}.
138 * {@link java.awt.RenderingHints#VALUE_FRACTIONALMETRICS_DEFAULT VALUE_FRACTIONALMETRICS_DEFAULT}
139 * may be specified, in which case the mode used is implementation
140 * dependent.
141 * Any other value will throw <code>IllegalArgumentException</code>
142 * @throws IllegalArgumentException if the hints are not one of the
143 * legal values.
144 * @since 1.6
145 */
146 public FontRenderContext(AffineTransform tx, Object aaHint, Object fmHint){
147 if (tx != null && !tx.isIdentity()) {
148 this.tx = new AffineTransform(tx);
149 }
150 try {
151 if (KEY_TEXT_ANTIALIASING.isCompatibleValue(aaHint)) {
152 aaHintValue = aaHint;
153 } else {
154 throw new IllegalArgumentException("AA hint:" + aaHint);
155 }
156 } catch (Exception e) {
157 throw new IllegalArgumentException("AA hint:" +aaHint);
158 }
159 try {
160 if (KEY_FRACTIONALMETRICS.isCompatibleValue(fmHint)) {
161 fmHintValue = fmHint;
162 } else {
163 throw new IllegalArgumentException("FM hint:" + fmHint);
164 }
165 } catch (Exception e) {
166 throw new IllegalArgumentException("FM hint:" +fmHint);
167 }
168 }
169
170 /**
171 * Indicates whether or not this <code>FontRenderContext</code> object
172 * measures text in a transformed render context.
173 * @return <code>true</code> if this <code>FontRenderContext</code>
174 * object has a non-identity AffineTransform attribute.
175 * <code>false</code> otherwise.
176 * @see java.awt.font.FontRenderContext#getTransform
177 * @since 1.6
178 */
179 public boolean isTransformed() {
180 if (!defaulting) {
181 return tx != null;
182 } else {
183 return !getTransform().isIdentity();
184 }
185 }
186
187 /**
188 * Returns the integer type of the affine transform for this
189 * <code>FontRenderContext</code> as specified by
190 * {@link java.awt.geom.AffineTransform#getType()}
191 * @return the type of the transform.
192 * @see AffineTransform
193 * @since 1.6
194 */
195 public int getTransformType() {
196 if (!defaulting) {
197 if (tx == null) {
198 return AffineTransform.TYPE_IDENTITY;
199 } else {
200 return tx.getType();
201 }
202 } else {
203 return getTransform().getType();
204 }
205 }
206
207 /**
208 * Gets the transform that is used to scale typographical points
209 * to pixels in this <code>FontRenderContext</code>.
210 * @return the <code>AffineTransform</code> of this
211 * <code>FontRenderContext</code>.
212 * @see AffineTransform
213 */
214 public AffineTransform getTransform() {
215 return (tx == null) ? new AffineTransform() : new AffineTransform(tx);
216 }
217
218 /**
219 * Returns a boolean which indicates whether or not some form of
220 * antialiasing is specified by this <code>FontRenderContext</code>.
221 * Call {@link #getAntiAliasingHint() getAntiAliasingHint()}
222 * for the specific rendering hint value.
223 * @return <code>true</code>, if text is anti-aliased in this
224 * <code>FontRenderContext</code>; <code>false</code> otherwise.
225 * @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING
226 * @see #FontRenderContext(AffineTransform,boolean,boolean)
227 * @see #FontRenderContext(AffineTransform,Object,Object)
228 */
229 public boolean isAntiAliased() {
230 return !(aaHintValue == VALUE_TEXT_ANTIALIAS_OFF ||
231 aaHintValue == VALUE_TEXT_ANTIALIAS_DEFAULT);
232 }
233
234 /**
235 * Returns a boolean which whether text fractional metrics mode
236 * is used in this <code>FontRenderContext</code>.
237 * Call {@link #getFractionalMetricsHint() getFractionalMetricsHint()}
238 * to obtain the corresponding rendering hint value.
239 * @return <code>true</code>, if layout should be performed with
240 * fractional metrics; <code>false</code> otherwise.
241 * in this <code>FontRenderContext</code>.
242 * @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS
243 * @see #FontRenderContext(AffineTransform,boolean,boolean)
244 * @see #FontRenderContext(AffineTransform,Object,Object)
245 */
246 public boolean usesFractionalMetrics() {
247 return !(fmHintValue == VALUE_FRACTIONALMETRICS_OFF ||
248 fmHintValue == VALUE_FRACTIONALMETRICS_DEFAULT);
249 }
250
251 /**
252 * Return the text anti-aliasing rendering mode hint used in this
253 * <code>FontRenderContext</code>.
254 * This will be one of the text antialiasing rendering hint values
255 * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
256 * @return text anti-aliasing rendering mode hint used in this
257 * <code>FontRenderContext</code>.
258 * @since 1.6
259 */
260 public Object getAntiAliasingHint() {
261 if (defaulting) {
262 if (isAntiAliased()) {
263 return VALUE_TEXT_ANTIALIAS_ON;
264 } else {
265 return VALUE_TEXT_ANTIALIAS_OFF;
266 }
267 }
268 return aaHintValue;
269 }
270
271 /**
272 * Return the text fractional metrics rendering mode hint used in this
273 * <code>FontRenderContext</code>.
274 * This will be one of the text fractional metrics rendering hint values
275 * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
276 * @return the text fractional metrics rendering mode hint used in this
277 * <code>FontRenderContext</code>.
278 * @since 1.6
279 */
280 public Object getFractionalMetricsHint() {
281 if (defaulting) {
282 if (usesFractionalMetrics()) {
283 return VALUE_FRACTIONALMETRICS_ON;
284 } else {
285 return VALUE_FRACTIONALMETRICS_OFF;
286 }
287 }
288 return fmHintValue;
289 }
290
291 /**
292 * Return true if obj is an instance of FontRenderContext and has the same
293 * transform, antialiasing, and fractional metrics values as this.
294 * @param obj the object to test for equality
295 * @return <code>true</code> if the specified object is equal to
296 * this <code>FontRenderContext</code>; <code>false</code>
297 * otherwise.
298 */
299 public boolean equals(Object obj) {
300 try {
301 return equals((FontRenderContext)obj);
302 }
303 catch (ClassCastException e) {
304 return false;
305 }
306 }
307
308 /**
309 * Return true if rhs has the same transform, antialiasing,
310 * and fractional metrics values as this.
311 * @param rhs the <code>FontRenderContext</code> to test for equality
312 * @return <code>true</code> if <code>rhs</code> is equal to
313 * this <code>FontRenderContext</code>; <code>false</code>
314 * otherwise.
315 * @since 1.4
316 */
317 public boolean equals(FontRenderContext rhs) {
318 if (this == rhs) {
319 return true;
320 }
321 if (rhs == null) {
322 return false;
323 }
324
325 /* if neither instance is a subclass, reference values directly. */
326 if (!rhs.defaulting && !defaulting) {
327 if (rhs.aaHintValue == aaHintValue &&
328 rhs.fmHintValue == fmHintValue) {
329
330 return tx == null ? rhs.tx == null : tx.equals(rhs.tx);
331 }
332 return false;
333 } else {
334 return
335 rhs.getAntiAliasingHint() == getAntiAliasingHint() &&
336 rhs.getFractionalMetricsHint() == getFractionalMetricsHint() &&
337 rhs.getTransform().equals(getTransform());
338 }
339 }
340
341 /**
342 * Return a hashcode for this FontRenderContext.
343 */
344 public int hashCode() {
345 int hash = tx == null ? 0 : tx.hashCode();
346 /* SunHints value objects have identity hashcode, so we can rely on
347 * this to ensure that two equal FRC's have the same hashcode.
348 */
349 if (defaulting) {
350 hash += getAntiAliasingHint().hashCode();
351 hash += getFractionalMetricsHint().hashCode();
352 } else {
353 hash += aaHintValue.hashCode();
354 hash += fmHintValue.hashCode();
355 }
356 return hash;
357 }
358 }
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