001 /* InputMethodRequests.java -- handles text insertion via input methods
002 Copyright (C) 2002, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
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009 any later version.
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020
021 Linking this library statically or dynamically with other modules is
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036 exception statement from your version. */
037
038 package java.awt.im;
039
040 import java.awt.Component;
041 import java.awt.Rectangle;
042 import java.awt.font.TextHitInfo;
043 import java.awt.event.InputMethodListener;
044 import java.text.AttributedCharacterIterator;
045 import java.text.AttributedCharacterIterator.Attribute;
046
047 /**
048 * This interface handles requests made by input methods on text editing
049 * components. A component must specify a handler for input methods that
050 * implements this interface, and which supports one of two user interfaces:
051 * <ul><li><em>on-the-spot</em>: composed text is shown in place</li>
052 * <li><em>below-the-spot</em>: composed text is in a separate window,
053 * usually below the main text window, until it is committed into place at
054 * the insertion point, overwriting any selected text</li></ul>
055 *
056 * @author Eric Blake (ebb9@email.byu.edu)
057 * @see Component#getInputMethodRequests()
058 * @see InputMethodListener
059 * @since 1.2
060 * @status updated to 1.4
061 */
062 public interface InputMethodRequests
063 {
064 /**
065 * Gets the location of a given offset of the text. This can be used to
066 * position a composition window near the location of where the composed
067 * text will be inserted.
068 *
069 * <p>If the component has composed text (from the most recent
070 * InputMethodEvent), then offset 0 indicates the location of the first
071 * character of this composed text. Otherwise, the offset is ignored, and
072 * the location should be the beginning of the final line of selected
073 * text (in horizontal left-to-right text, like English, this would be the
074 * lower left corner of the selction; in vertical top-to-bottom text, like
075 * Chinese, this would be the top right corner of the selection).
076 *
077 * <p>The location returned is a 0-thickness caret (either horizontal or
078 * vertical, depending on text flow), mapped to absolute screen coordinates.
079 *
080 * @param offset offset within composed text, or null
081 * @return the screen location of the caret at the offset
082 */
083 Rectangle getTextLocation(TextHitInfo offset);
084
085 /**
086 * Get the text offset for the given screen coordinate. The offset is
087 * relative to the composed text, and the return is null if it is outside
088 * the range of composed text. For example, this can be used to find
089 * where a mouse click should pop up a text composition window.
090 *
091 * @param x the x screen coordinate
092 * @param y the y screen coordinate
093 * @return a text hit info describing the composed text offset
094 */
095 TextHitInfo getLocationOffset(int x, int y);
096
097 /**
098 * Gets the offset where the committed text exists in the text editing
099 * component. This can be used to examine the text surrounding the insert
100 * position.
101 *
102 * @return the offset of the insert position
103 */
104 int getInsertPositionOffset();
105
106 /**
107 * Gets an interator which provides access to the text and its attributes,
108 * except for the uncommitted text. The input method may provide a list of
109 * attributes it is interested in; and the iterator need not provide
110 * information on the remaining attributes. If the attribute list is null,
111 * the iterator must list all attributes.
112 *
113 * @param beginIndex the index of the first character in the iteration
114 * @param endIndex the index of the last character in the iteration
115 * @param attributes a list of attributes interested in, or null
116 * @return an iterator over the region of text with its attributes
117 */
118 AttributedCharacterIterator getCommittedText(int beginIndex, int endIndex,
119 Attribute[] attributes);
120
121 /**
122 * Gets the length of committed text.
123 *
124 * @return the number of committed characters
125 */
126 int getCommittedTextLength();
127
128 /**
129 * Gets the latest committed text, and removes it from the component's text
130 * body. This allows an input method to provide an "Undo" command. In
131 * general, this should only be supported immediately after a commit, and
132 * not when other actions intervene; if not supported, simply return null.
133 * The input method may provide a list of attributes it is interested in;
134 * and the iterator need not provide information on the remaining attributes.
135 * If the attribute list is null, the iterator must list all attributes.
136 *
137 * @param attributes a list of attributes interested in, or null
138 * @return the latest committed text, or null
139 */
140 AttributedCharacterIterator cancelLatestCommittedText
141 (Attribute[] attributes);
142
143 /**
144 * Gets the currently selected text. One use of this is to implement a
145 * "Reconvert" feature in an input method, which modifies the selection
146 * based on the text in the composition window. The input method may
147 * provide a list of attributes it is interested in; and the iterator need
148 * not provide information on the remaining attributes. If the attribute
149 * list is null, the iterator must list all attributes.
150 *
151 * @param attributes a list of attributes interested in, or null
152 * @return the current selection
153 */
154 AttributedCharacterIterator getSelectedText(Attribute[] attributes);
155 } // interface InputMethodRequests