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    1   /*
    2    * Copyright (c) 1997, 2006, 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 >= 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 >= 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 >= 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 >= 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 >= 0
  201        */
  202       public void moveDot(int dot);
  203   
  204   };

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