Layout paragraph text by Breaking text to next line with LineBreakMeasurer and TextLayout

Description

Demo Code



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;

/**//from  w ww  . j  a v  a 2 s .co  m
 * 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);
    }
}

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions 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 Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
Layout paragraph text by Breaking text to next line with LineBreakMeasurer and TextLayout - Java 2D Graphics

Description

Demo Code

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