https://openjdk.java.net/ 
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package javax.swing.text;

import java.awt.Graphics;
import java.awt.Point;
import javax.swing.Action;
import javax.swing.event.ChangeListener;


A place within a document view that represents where
things can be inserted into the document model.  A caret
has a position in the document referred to as a dot.
The dot is where the caret is currently located in the
model.  There is
a second position maintained by the caret that represents
the other end of a selection called mark.  If there is
no selection the dot and mark will be equal.  If a selection
exists, the two values will be different.


The dot can be placed by either calling
setDot or moveDot.  Setting
the dot has the effect of removing any selection that may
have previously existed.  The dot and mark will be equal.
Moving the dot has the effect of creating a selection as
the mark is left at whatever position it previously had.

Author: Timothy Prinzing
/**
 * A place within a document view that represents where
 * things can be inserted into the document model.  A caret
 * has a position in the document referred to as a dot.
 * The dot is where the caret is currently located in the
 * model.  There is
 * a second position maintained by the caret that represents
 * the other end of a selection called mark.  If there is
 * no selection the dot and mark will be equal.  If a selection
 * exists, the two values will be different.
 * <p>
 * The dot can be placed by either calling
 * <code>setDot</code> or <code>moveDot</code>.  Setting
 * the dot has the effect of removing any selection that may
 * have previously existed.  The dot and mark will be equal.
 * Moving the dot has the effect of creating a selection as
 * the mark is left at whatever position it previously had.
 *
 * @author  Timothy Prinzing
 */
public interface Caret {

    
Called when the UI is being installed into the
interface of a JTextComponent.  This can be used
to gain access to the model that is being navigated
by the implementation of this interface.

Params:
  • c – the JTextComponent
/**
     * Called when the UI is being installed into the
     * interface of a JTextComponent.  This can be used
     * to gain access to the model that is being navigated
     * by the implementation of this interface.
     *
     * @param c the JTextComponent
     */
    public void install(JTextComponent c);

    
Called when the UI is being removed from the
interface of a JTextComponent.  This is used to
unregister any listeners that were attached.

Params:
  • c – the JTextComponent
/**
     * Called when the UI is being removed from the
     * interface of a JTextComponent.  This is used to
     * unregister any listeners that were attached.
     *
     * @param c the JTextComponent
     */
    public void deinstall(JTextComponent c);

    
Renders the caret. This method is called by UI classes.

Params:
  • g – the graphics context
/**
     * Renders the caret. This method is called by UI classes.
     *
     * @param g the graphics context
     */
    public void paint(Graphics g);

    
Adds a listener to track whenever the caret position
has been changed.

Params:
  • l – the change listener
/**
     * Adds a listener to track whenever the caret position
     * has been changed.
     *
     * @param l the change listener
     */
    public void addChangeListener(ChangeListener l);

    
Removes a listener that was tracking caret position changes.

Params:
  • l – the change listener
/**
     * Removes a listener that was tracking caret position changes.
     *
     * @param l the change listener
     */
    public void removeChangeListener(ChangeListener l);

    
Determines if the caret is currently visible.

Returns:true if the caret is visible else false
/**
     * Determines if the caret is currently visible.
     *
     * @return true if the caret is visible else false
     */
    public boolean isVisible();

    
Sets the visibility of the caret.

Params:
  • v –  true if the caret should be shown,
 and false if the caret should be hidden
/**
     * Sets the visibility of the caret.
     *
     * @param v  true if the caret should be shown,
     *  and false if the caret should be hidden
     */
    public void setVisible(boolean v);

    
Determines if the selection is currently visible.

Returns:true if the caret is visible else false
/**
     * Determines if the selection is currently visible.
     *
     * @return true if the caret is visible else false
     */
    public boolean isSelectionVisible();

    
Sets the visibility of the selection

Params:
  • v –  true if the caret should be shown,
 and false if the caret should be hidden
/**
     * Sets the visibility of the selection
     *
     * @param v  true if the caret should be shown,
     *  and false if the caret should be hidden
     */
    public void setSelectionVisible(boolean v);

    
Set the current caret visual location.  This can be used when
moving between lines that have uneven end positions (such as
when caret up or down actions occur).  If text flows
left-to-right or right-to-left the x-coordinate will indicate
the desired navigation location for vertical movement.  If
the text flow is top-to-bottom, the y-coordinate will indicate
the desired navigation location for horizontal movement.

Params:
  • p –  the Point to use for the saved position.  This
  can be null to indicate there is no visual location.
/**
     * Set the current caret visual location.  This can be used when
     * moving between lines that have uneven end positions (such as
     * when caret up or down actions occur).  If text flows
     * left-to-right or right-to-left the x-coordinate will indicate
     * the desired navigation location for vertical movement.  If
     * the text flow is top-to-bottom, the y-coordinate will indicate
     * the desired navigation location for horizontal movement.
     *
     * @param p  the Point to use for the saved position.  This
     *   can be null to indicate there is no visual location.
     */
    public void setMagicCaretPosition(Point p);

    
Gets the current caret visual location.

See Also:
Returns:the visual position.
/**
     * Gets the current caret visual location.
     *
     * @return the visual position.
     * @see #setMagicCaretPosition
     */
    public Point getMagicCaretPosition();

    
Sets the blink rate of the caret.  This determines if
and how fast the caret blinks, commonly used as one
way to attract attention to the caret.

Params:
  • rate –  the delay in milliseconds >= 0.  If this is
 zero the caret will not blink.
/**
     * Sets the blink rate of the caret.  This determines if
     * and how fast the caret blinks, commonly used as one
     * way to attract attention to the caret.
     *
     * @param rate  the delay in milliseconds >= 0.  If this is
     *  zero the caret will not blink.
     */
    public void setBlinkRate(int rate);

    
Gets the blink rate of the caret.  This determines if
and how fast the caret blinks, commonly used as one
way to attract attention to the caret.

Returns:the delay in milliseconds >= 0.  If this is
 zero the caret will not blink.
/**
     * Gets the blink rate of the caret.  This determines if
     * and how fast the caret blinks, commonly used as one
     * way to attract attention to the caret.
     *
     * @return the delay in milliseconds >= 0.  If this is
     *  zero the caret will not blink.
     */
    public int getBlinkRate();

    
Fetches the current position of the caret.

Returns:the position >= 0
/**
     * Fetches the current position of the caret.
     *
     * @return the position >= 0
     */
    public int getDot();

    
Fetches the current position of the mark.  If there
is a selection, the mark will not be the same as
the dot.

Returns:the position >= 0
/**
     * Fetches the current position of the mark.  If there
     * is a selection, the mark will not be the same as
     * the dot.
     *
     * @return the position >= 0
     */
    public int getMark();

    
Sets the caret position to some position.  This
causes the mark to become the same as the dot,
effectively setting the selection range to zero.


If the parameter is negative or beyond the length of the document,
the caret is placed at the beginning or at the end, respectively.

Params:
  • dot –  the new position to set the caret to
/**
     * Sets the caret position to some position.  This
     * causes the mark to become the same as the dot,
     * effectively setting the selection range to zero.
     * <p>
     * If the parameter is negative or beyond the length of the document,
     * the caret is placed at the beginning or at the end, respectively.
     *
     * @param dot  the new position to set the caret to
     */
    public void setDot(int dot);

    
Moves the caret position (dot) to some other position,
leaving behind the mark.  This is useful for
making selections.

Params:
  • dot –  the new position to move the caret to >= 0
/**
     * Moves the caret position (dot) to some other position,
     * leaving behind the mark.  This is useful for
     * making selections.
     *
     * @param dot  the new position to move the caret to >= 0
     */
    public void moveDot(int dot);

};