001 /*
002 * Copyright 1996-2003 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.beans;
027
028 /**
029 * A PropertyEditor class provides support for GUIs that want to
030 * allow users to edit a property value of a given type.
031 * <p>
032 * PropertyEditor supports a variety of different kinds of ways of
033 * displaying and updating property values. Most PropertyEditors will
034 * only need to support a subset of the different options available in
035 * this API.
036 * <P>
037 * Simple PropertyEditors may only support the getAsText and setAsText
038 * methods and need not support (say) paintValue or getCustomEditor. More
039 * complex types may be unable to support getAsText and setAsText but will
040 * instead support paintValue and getCustomEditor.
041 * <p>
042 * Every propertyEditor must support one or more of the three simple
043 * display styles. Thus it can either (1) support isPaintable or (2)
044 * both return a non-null String[] from getTags() and return a non-null
045 * value from getAsText or (3) simply return a non-null String from
046 * getAsText().
047 * <p>
048 * Every property editor must support a call on setValue when the argument
049 * object is of the type for which this is the corresponding propertyEditor.
050 * In addition, each property editor must either support a custom editor,
051 * or support setAsText.
052 * <p>
053 * Each PropertyEditor should have a null constructor.
054 */
055
056 public interface PropertyEditor {
057
058 /**
059 * Set (or change) the object that is to be edited. Primitive types such
060 * as "int" must be wrapped as the corresponding object type such as
061 * "java.lang.Integer".
062 *
063 * @param value The new target object to be edited. Note that this
064 * object should not be modified by the PropertyEditor, rather
065 * the PropertyEditor should create a new object to hold any
066 * modified value.
067 */
068 void setValue(Object value);
069
070 /**
071 * Gets the property value.
072 *
073 * @return The value of the property. Primitive types such as "int" will
074 * be wrapped as the corresponding object type such as "java.lang.Integer".
075 */
076
077 Object getValue();
078
079 //----------------------------------------------------------------------
080
081 /**
082 * Determines whether this property editor is paintable.
083 *
084 * @return True if the class will honor the paintValue method.
085 */
086
087 boolean isPaintable();
088
089 /**
090 * Paint a representation of the value into a given area of screen
091 * real estate. Note that the propertyEditor is responsible for doing
092 * its own clipping so that it fits into the given rectangle.
093 * <p>
094 * If the PropertyEditor doesn't honor paint requests (see isPaintable)
095 * this method should be a silent noop.
096 * <p>
097 * The given Graphics object will have the default font, color, etc of
098 * the parent container. The PropertyEditor may change graphics attributes
099 * such as font and color and doesn't need to restore the old values.
100 *
101 * @param gfx Graphics object to paint into.
102 * @param box Rectangle within graphics object into which we should paint.
103 */
104 void paintValue(java.awt.Graphics gfx, java.awt.Rectangle box);
105
106 //----------------------------------------------------------------------
107
108 /**
109 * Returns a fragment of Java code that can be used to set a property
110 * to match the editors current state. This method is intended
111 * for use when generating Java code to reflect changes made through the
112 * property editor.
113 * <p>
114 * The code fragment should be context free and must be a legal Java
115 * expression as specified by the JLS.
116 * <p>
117 * Specifically, if the expression represents a computation then all
118 * classes and static members should be fully qualified. This rule
119 * applies to constructors, static methods and non primitive arguments.
120 * <p>
121 * Caution should be used when evaluating the expression as it may throw
122 * exceptions. In particular, code generators must ensure that generated
123 * code will compile in the presence of an expression that can throw
124 * checked exceptions.
125 * <p>
126 * Example results are:
127 * <ul>
128 * <li>Primitive expresssion: <code>2</code>
129 * <li>Class constructor: <code>new java.awt.Color(127,127,34)</code>
130 * <li>Static field: <code>java.awt.Color.orange</code>
131 * <li>Static method: <code>javax.swing.Box.createRigidArea(new
132 * java.awt.Dimension(0, 5))</code>
133 * </ul>
134 *
135 * @return a fragment of Java code representing an initializer for the
136 * current value. It should not contain a semi-colon
137 * ('<code>;</code>') to end the expression.
138 */
139 String getJavaInitializationString();
140
141 //----------------------------------------------------------------------
142
143 /**
144 * Gets the property value as text.
145 *
146 * @return The property value as a human editable string.
147 * <p> Returns null if the value can't be expressed as an editable string.
148 * <p> If a non-null value is returned, then the PropertyEditor should
149 * be prepared to parse that string back in setAsText().
150 */
151 String getAsText();
152
153 /**
154 * Set the property value by parsing a given String. May raise
155 * java.lang.IllegalArgumentException if either the String is
156 * badly formatted or if this kind of property can't be expressed
157 * as text.
158 * @param text The string to be parsed.
159 */
160 void setAsText(String text)
161 throws java.lang.IllegalArgumentException;
162
163 //----------------------------------------------------------------------
164
165 /**
166 * If the property value must be one of a set of known tagged values,
167 * then this method should return an array of the tags. This can
168 * be used to represent (for example) enum values. If a PropertyEditor
169 * supports tags, then it should support the use of setAsText with
170 * a tag value as a way of setting the value and the use of getAsText
171 * to identify the current value.
172 *
173 * @return The tag values for this property. May be null if this
174 * property cannot be represented as a tagged value.
175 *
176 */
177 String[] getTags();
178
179 //----------------------------------------------------------------------
180
181 /**
182 * A PropertyEditor may choose to make available a full custom Component
183 * that edits its property value. It is the responsibility of the
184 * PropertyEditor to hook itself up to its editor Component itself and
185 * to report property value changes by firing a PropertyChange event.
186 * <P>
187 * The higher-level code that calls getCustomEditor may either embed
188 * the Component in some larger property sheet, or it may put it in
189 * its own individual dialog, or ...
190 *
191 * @return A java.awt.Component that will allow a human to directly
192 * edit the current property value. May be null if this is
193 * not supported.
194 */
195
196 java.awt.Component getCustomEditor();
197
198 /**
199 * Determines whether this property editor supports a custom editor.
200 *
201 * @return True if the propertyEditor can provide a custom editor.
202 */
203 boolean supportsCustomEditor();
204
205 //----------------------------------------------------------------------
206
207 /**
208 * Register a listener for the PropertyChange event. When a
209 * PropertyEditor changes its value it should fire a PropertyChange
210 * event on all registered PropertyChangeListeners, specifying the
211 * null value for the property name and itself as the source.
212 *
213 * @param listener An object to be invoked when a PropertyChange
214 * event is fired.
215 */
216 void addPropertyChangeListener(PropertyChangeListener listener);
217
218 /**
219 * Remove a listener for the PropertyChange event.
220 *
221 * @param listener The PropertyChange listener to be removed.
222 */
223 void removePropertyChangeListener(PropertyChangeListener listener);
224
225 }
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