1 /*
2 * Copyright 1997-2007 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 package javax.swing.text;
26
27 import java.util.Enumeration;
28
29 /**
30 * A collection of unique attributes. This is a read-only,
31 * immutable interface. An attribute is basically a key and
32 * a value assigned to the key. The collection may represent
33 * something like a style run, a logical style, etc. These
34 * are generally used to describe features that will contribute
35 * to some graphical representation such as a font. The
36 * set of possible keys is unbounded and can be anything.
37 * Typically View implementations will respond to attribute
38 * definitions and render something to represent the attributes.
39 * <p>
40 * Attributes can potentially resolve in a hierarchy. If a
41 * key doesn't resolve locally, and a resolving parent
42 * exists, the key will be resolved through the parent.
43 *
44 * @author Timothy Prinzing
45 * @see MutableAttributeSet
46 */
47 public interface AttributeSet {
48
49 /**
50 * This interface is the type signature that is expected
51 * to be present on any attribute key that contributes to
52 * the determination of what font to use to render some
53 * text. This is not considered to be a closed set, the
54 * definition can change across version of the platform and can
55 * be amended by additional user added entries that
56 * correspond to logical settings that are specific to
57 * some type of content.
58 */
59 public interface FontAttribute {
60 }
61
62 /**
63 * This interface is the type signature that is expected
64 * to be present on any attribute key that contributes to
65 * presentation of color.
66 */
67 public interface ColorAttribute {
68 }
69
70 /**
71 * This interface is the type signature that is expected
72 * to be present on any attribute key that contributes to
73 * character level presentation. This would be any attribute
74 * that applies to a so-called <term>run</term> of
75 * style.
76 */
77 public interface CharacterAttribute {
78 }
79
80 /**
81 * This interface is the type signature that is expected
82 * to be present on any attribute key that contributes to
83 * the paragraph level presentation.
84 */
85 public interface ParagraphAttribute {
86 }
87
88 /**
89 * Returns the number of attributes that are defined locally in this set.
90 * Attributes that are defined in the parent set are not included.
91 *
92 * @return the number of attributes >= 0
93 */
94 public int getAttributeCount();
95
96 /**
97 * Checks whether the named attribute has a value specified in
98 * the set without resolving through another attribute
99 * set.
100 *
101 * @param attrName the attribute name
102 * @return true if the attribute has a value specified
103 */
104 public boolean isDefined(Object attrName);
105
106 /**
107 * Determines if the two attribute sets are equivalent.
108 *
109 * @param attr an attribute set
110 * @return true if the sets are equivalent
111 */
112 public boolean isEqual(AttributeSet attr);
113
114 /**
115 * Returns an attribute set that is guaranteed not
116 * to change over time.
117 *
118 * @return a copy of the attribute set
119 */
120 public AttributeSet copyAttributes();
121
122 /**
123 * Fetches the value of the given attribute. If the value is not found
124 * locally, the search is continued upward through the resolving
125 * parent (if one exists) until the value is either
126 * found or there are no more parents. If the value is not found,
127 * null is returned.
128 *
129 * @param key the non-null key of the attribute binding
130 * @return the value of the attribute, or {@code null} if not found
131 */
132 public Object getAttribute(Object key);
133
134 /**
135 * Returns an enumeration over the names of the attributes that are
136 * defined locally in the set. Names of attributes defined in the
137 * resolving parent, if any, are not included. The values of the
138 * <code>Enumeration</code> may be anything and are not constrained to
139 * a particular <code>Object</code> type.
140 * <p>
141 * This method never returns {@code null}. For a set with no attributes, it
142 * returns an empty {@code Enumeration}.
143 *
144 * @return the names
145 */
146 public Enumeration<?> getAttributeNames();
147
148 /**
149 * Returns {@code true} if this set defines an attribute with the same
150 * name and an equal value. If such an attribute is not found locally,
151 * it is searched through in the resolving parent hierarchy.
152 *
153 * @param name the non-null attribute name
154 * @param value the value
155 * @return {@code true} if the set defines the attribute with an
156 * equal value, either locally or through its resolving parent
157 * @throws NullPointerException if either {@code name} or
158 * {@code value} is {@code null}
159 */
160 public boolean containsAttribute(Object name, Object value);
161
162 /**
163 * Returns {@code true} if this set defines all the attributes from the
164 * given set with equal values. If an attribute is not found locally,
165 * it is searched through in the resolving parent hierarchy.
166 *
167 * @param attributes the set of attributes to check against
168 * @return {@code true} if this set defines all the attributes with equal
169 * values, either locally or through its resolving parent
170 * @throws NullPointerException if {@code attributes} is {@code null}
171 */
172 public boolean containsAttributes(AttributeSet attributes);
173
174 /**
175 * Gets the resolving parent.
176 *
177 * @return the parent
178 */
179 public AttributeSet getResolveParent();
180
181 /**
182 * Attribute name used to name the collection of
183 * attributes.
184 */
185 public static final Object NameAttribute = StyleConstants.NameAttribute;
186
187 /**
188 * Attribute name used to identify the resolving parent
189 * set of attributes, if one is defined.
190 */
191 public static final Object ResolveAttribute = StyleConstants.ResolveAttribute;
192
193 }
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