View Javadoc
1   /*
2    * Copyright (c) 1997, 2013, 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  package javax.swing.text;
26  
27  import java.awt.Graphics;
28  import java.awt.Point;
29  import javax.swing.Action;
30  import javax.swing.event.ChangeListener;
31  
32  /**
33   * A place within a document view that represents where
34   * things can be inserted into the document model.  A caret
35   * has a position in the document referred to as a dot.
36   * The dot is where the caret is currently located in the
37   * model.  There is
38   * a second position maintained by the caret that represents
39   * the other end of a selection called mark.  If there is
40   * no selection the dot and mark will be equal.  If a selection
41   * exists, the two values will be different.
42   * <p>
43   * The dot can be placed by either calling
44   * <code>setDot</code> or <code>moveDot</code>.  Setting
45   * the dot has the effect of removing any selection that may
46   * have previously existed.  The dot and mark will be equal.
47   * Moving the dot has the effect of creating a selection as
48   * the mark is left at whatever position it previously had.
49   *
50   * @author  Timothy Prinzing
51   */
52  public interface Caret {
53  
54      /**
55       * Called when the UI is being installed into the
56       * interface of a JTextComponent.  This can be used
57       * to gain access to the model that is being navigated
58       * by the implementation of this interface.
59       *
60       * @param c the JTextComponent
61       */
62      public void install(JTextComponent c);
63  
64      /**
65       * Called when the UI is being removed from the
66       * interface of a JTextComponent.  This is used to
67       * unregister any listeners that were attached.
68       *
69       * @param c the JTextComponent
70       */
71      public void deinstall(JTextComponent c);
72  
73      /**
74       * Renders the caret. This method is called by UI classes.
75       *
76       * @param g the graphics context
77       */
78      public void paint(Graphics g);
79  
80      /**
81       * Adds a listener to track whenever the caret position
82       * has been changed.
83       *
84       * @param l the change listener
85       */
86      public void addChangeListener(ChangeListener l);
87  
88      /**
89       * Removes a listener that was tracking caret position changes.
90       *
91       * @param l the change listener
92       */
93      public void removeChangeListener(ChangeListener l);
94  
95      /**
96       * Determines if the caret is currently visible.
97       *
98       * @return true if the caret is visible else false
99       */
100     public boolean isVisible();
101 
102     /**
103      * Sets the visibility of the caret.
104      *
105      * @param v  true if the caret should be shown,
106      *  and false if the caret should be hidden
107      */
108     public void setVisible(boolean v);
109 
110     /**
111      * Determines if the selection is currently visible.
112      *
113      * @return true if the caret is visible else false
114      */
115     public boolean isSelectionVisible();
116 
117     /**
118      * Sets the visibility of the selection
119      *
120      * @param v  true if the caret should be shown,
121      *  and false if the caret should be hidden
122      */
123     public void setSelectionVisible(boolean v);
124 
125     /**
126      * Set the current caret visual location.  This can be used when
127      * moving between lines that have uneven end positions (such as
128      * when caret up or down actions occur).  If text flows
129      * left-to-right or right-to-left the x-coordinate will indicate
130      * the desired navigation location for vertical movement.  If
131      * the text flow is top-to-bottom, the y-coordinate will indicate
132      * the desired navigation location for horizontal movement.
133      *
134      * @param p  the Point to use for the saved position.  This
135      *   can be null to indicate there is no visual location.
136      */
137     public void setMagicCaretPosition(Point p);
138 
139     /**
140      * Gets the current caret visual location.
141      *
142      * @return the visual position.
143      * @see #setMagicCaretPosition
144      */
145     public Point getMagicCaretPosition();
146 
147     /**
148      * Sets the blink rate of the caret.  This determines if
149      * and how fast the caret blinks, commonly used as one
150      * way to attract attention to the caret.
151      *
152      * @param rate  the delay in milliseconds &gt;=0.  If this is
153      *  zero the caret will not blink.
154      */
155     public void setBlinkRate(int rate);
156 
157     /**
158      * Gets the blink rate of the caret.  This determines if
159      * and how fast the caret blinks, commonly used as one
160      * way to attract attention to the caret.
161      *
162      * @return the delay in milliseconds &gt;=0.  If this is
163      *  zero the caret will not blink.
164      */
165     public int getBlinkRate();
166 
167     /**
168      * Fetches the current position of the caret.
169      *
170      * @return the position &gt;=0
171      */
172     public int getDot();
173 
174     /**
175      * Fetches the current position of the mark.  If there
176      * is a selection, the mark will not be the same as
177      * the dot.
178      *
179      * @return the position &gt;=0
180      */
181     public int getMark();
182 
183     /**
184      * Sets the caret position to some position.  This
185      * causes the mark to become the same as the dot,
186      * effectively setting the selection range to zero.
187      * <p>
188      * If the parameter is negative or beyond the length of the document,
189      * the caret is placed at the beginning or at the end, respectively.
190      *
191      * @param dot  the new position to set the caret to
192      */
193     public void setDot(int dot);
194 
195     /**
196      * Moves the caret position (dot) to some other position,
197      * leaving behind the mark.  This is useful for
198      * making selections.
199      *
200      * @param dot  the new position to move the caret to &gt;=0
201      */
202     public void moveDot(int dot);
203 
204 };