blockcaret.java

来自「具有不同语法高亮的编辑器实例」· Java 代码 · 共 139 行

/*
 * 11/14/2003
 *
 * BlockCaret.java - A block caret; useful for "overwrite" modes in
 *                   JTextComponents.
 * Copyright (C) 2003 Robert Futrell
 * [e-mail]
 * www.website.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package org.fife.ui;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.io.Serializable;
import javax.swing.plaf.TextUI;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultCaret;
import javax.swing.text.JTextComponent;
import javax.swing.text.Segment;


/**
 * A caret that draws a rectangular box around the current dot location in
 * the document.  The color used is the caret color specified by the
 * <code>JTextComponent</code>.  This caret is useful to visually signify
 * being in "overwrite mode."
 *
 * @author Robert Futrell
 * @version 1.0
 */
public class BlockCaret extends DefaultCaret implements Serializable {
		
	/**
	 * 
	 */
	private static final long serialVersionUID = 8765113138327312426L;

	/**
	 * Used for fastest-possible retrieval of the character at the
	 * caret's position in the document.
	 */
	private Segment segment;


/*****************************************************************************/


	/**
	 * Constructs a new <code>BlockCaret</code>.
	 */
	public BlockCaret() {
			super();
			segment = new Segment();
	}


/*****************************************************************************/


	/**
	 * Damages the area surrounding the caret to cause it to be repainted in a
	 * new location. If paint() is reimplemented, this method should also be
	 * reimplemented. This method should update the caret bounds
	 * (x, y, width, and height).
	 *
	 * @param r The current location of the caret.
	 */
	protected synchronized void damage(Rectangle r) {
		if (r != null) {
			JTextComponent component = getComponent();
			x = r.x;
			y = r.y;
			width = component.getFontMetrics(component.getFont()).
									charWidth( 'w' ); // Widest char.
			height = r.height;
			repaint();
		}
	}


/*****************************************************************************/


	/**
	 * Paints the block cursor.
	 *
	 * @param g The graphics context in which to paint.
	 */
	public void paint(Graphics g) {

		// If the cursor is currently visible...
		if (isVisible()) {

			// Draw a big rectangle, and xor the text (foreground) color.
			try {
				JTextComponent component = getComponent();
				TextUI mapper = component.getUI();
				int dot = getDot();
				Rectangle rect = mapper.modelToView(component, dot);
				try {
					component.getDocument().getText(dot,1, segment);
					width = g.getFontMetrics().charWidth(segment.array[segment.offset]);
					// For when we're at the end of a line, as the '\n'
					// char has width 0 (like all unprintable chars?).
					if (width==0)
						width = g.getFontMetrics().charWidth(' ');
				} catch (BadLocationException ble) {
					// Shouldn't ever happen.
					width = g.getFontMetrics().charWidth(' ');
				}
				g.setXORMode(Color.WHITE);
				g.setColor(component.getCaretColor());
				g.fillRect(rect.x,rect.y, width,rect.height-2);
			}
			catch (BadLocationException ble) { }

		}

	}


/*****************************************************************************/

}