Java tutorial
/* * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ 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. * <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. * * @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. * * @param c the JTextComponent */ public void deinstall(JTextComponent c); /** * 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. * * @param l the change listener */ public void addChangeListener(ChangeListener l); /** * 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. * * @return true if the caret is visible else false */ public boolean isVisible(); /** * 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. * * @return true if the caret is visible else false */ public boolean isSelectionVisible(); /** * 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. * * @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. * * @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. * * @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. * * @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. * * @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. * * @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. * <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. * * @param dot the new position to move the caret to >=0 */ public void moveDot(int dot); };