linebreaksample.java

来自「JAVA 工作指南 可以说是程序员必备的东西哦」· Java 代码 · 共 169 行

/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
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 */


import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Hashtable;

import java.awt.font.FontRenderContext;
import java.awt.font.LineBreakMeasurer;
import java.awt.font.TextAttribute;
import java.awt.font.TextLayout;
import java.text.AttributedCharacterIterator;
import java.text.AttributedString;

/**
 * This class demonstrates how to line-break and draw a paragraph 
 * of text using LineBreakMeasurer and TextLayout.
 *
 * This class constructs a LineBreakMeasurer from an
 * AttributedCharacterIterator.  It uses the LineBreakMeasurer
 * to create and draw TextLayouts (lines of text) which fit within 
 * the Component's width.
 */

class LineBreakPanel extends JPanel {

    // The LineBreakMeasurer used to line-break the paragraph.
    private LineBreakMeasurer lineMeasurer;

    // index of the first character in the paragraph.
    private int paragraphStart;

    // index of the first character after the end of the paragraph.
    private int paragraphEnd;

    private static final 
        Hashtable<TextAttribute, Object> map =
           new Hashtable<TextAttribute, Object>();

    static {
        map.put(TextAttribute.FAMILY, "Serif");
        map.put(TextAttribute.SIZE, new Float(18.0));
    }  

    private static AttributedString vanGogh = new AttributedString(
        "Many people believe that Vincent van Gogh painted his best works " +
        "during the two-year period he spent in Provence. Here is where he " +
        "painted The Starry Night--which some consider to be his greatest " +
        "work of all. However, as his artistic brilliance reached new " +
        "heights in Provence, his physical and mental health plummeted. ",
        map);

    public void paintComponent(Graphics g) {

	super.paintComponent(g);
        setBackground(Color.white);

        Graphics2D g2d = (Graphics2D)g;

        // Create a new LineBreakMeasurer from the paragraph.
        // It will be cached and re-used.
        if (lineMeasurer == null) {
            AttributedCharacterIterator paragraph = vanGogh.getIterator();
            paragraphStart = paragraph.getBeginIndex();
            paragraphEnd = paragraph.getEndIndex();
            FontRenderContext frc = g2d.getFontRenderContext();
            lineMeasurer = new LineBreakMeasurer(paragraph, frc);
        }

        // Set break width to width of Component.
        float breakWidth = (float)getSize().width;
        float drawPosY = 0;
        // Set position to the index of the first character in the paragraph.
        lineMeasurer.setPosition(paragraphStart);

        // Get lines until the entire paragraph has been displayed.
        while (lineMeasurer.getPosition() < paragraphEnd) {

            // Retrieve next layout. A cleverer program would also cache
            // these layouts until the component is re-sized.
            TextLayout layout = lineMeasurer.nextLayout(breakWidth);

            // Compute pen x position. If the paragraph is right-to-left we
            // will align the TextLayouts to the right edge of the panel.
            // Note: this won't occur for the English text in this sample.
            // Note: drawPosX is always where the LEFT of the text is placed.
            float drawPosX = layout.isLeftToRight()
                ? 0 : breakWidth - layout.getAdvance();

            // Move y-coordinate by the ascent of the layout.
            drawPosY += layout.getAscent();

            // Draw the TextLayout at (drawPosX, drawPosY).
            layout.draw(g2d, drawPosX, drawPosY);

            // Move y-coordinate in preparation for next layout.
            drawPosY += layout.getDescent() + layout.getLeading();
        }
    }

}

public class LineBreakSample extends JApplet {
          
    public void init() {
	buildUI(getContentPane());
    }

    public void buildUI(Container container) {
        try {
            String cn = UIManager.getSystemLookAndFeelClassName();
            UIManager.setLookAndFeel(cn);
        } catch (Exception cnf) {
        }
        LineBreakPanel lineBreakPanel = new LineBreakPanel();
	container.add(lineBreakPanel, BorderLayout.CENTER);
    }

    public static void main(String[] args) {

        JFrame f = new JFrame("Line Break Sample");
            
        f.addWindowListener(new WindowAdapter(){
                public void windowClosing(WindowEvent e) {
                    System.exit(0);
                }
            });

        LineBreakSample lineBreakSample = new LineBreakSample();
	lineBreakSample.buildUI(f.getContentPane());        
        f.setSize(new Dimension(400, 250));
        f.setVisible(true);
    }
}