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可能重复：
第 2 部分 - 缩放 JTextPane 时如何获得一致的渲染？

我想允许用户放大或缩小不可编辑的 JTextPane。

运行下面的示例程序，我发现缩放 Graphics 对象会导致粗体文本和非粗体文本之间的间距不一致。如果粗体和非粗体之间有一个空格，有时它会被渲染得太宽，而在其他缩放级别上，空格会消失并且相邻的字符会重叠。

如果没有渲染提示，间距在 100% 时正确，但在其他缩放级别不正确。使用 KEY_FRACTIONALMETRICS 渲染提示，结果在所有缩放级别都是一致的，但粗体和非粗体之间的间距即使在 100% 时也是错误的。

我用 Java 1.6.0_13 和 1.6.0_23 都试过了。结果是一样的。有什么建议可以在所有缩放级别上实现有吸引力的缩放渲染吗？

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextPane;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.Style;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyleContext;
import javax.swing.text.StyledDocument;

public class ScaledJTextPane extends JTextPane
{
    double scale_;

    public ScaledJTextPane()
    {
        scale_ = 1.0;
    }

    protected void paintComponent(Graphics g)
    {
        Graphics2D g2 = (Graphics2D) g;

        // Try with and without the rendering hint
        g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS,
                RenderingHints.VALUE_FRACTIONALMETRICS_ON);
        g2.scale(scale_, scale_);

        super.paintComponent(g2);
    }

    public void setScale(double scale)
    {
        scale_ = scale;
    }

    private static void createAndShowGUI() 
    {
        // Create and set up the window.
        JFrame frame = new JFrame("ScaledJTextPane");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        final ScaledJTextPane scaledTextPane = new ScaledJTextPane();
        StyledDocument doc = scaledTextPane.getStyledDocument();
        Style defaultStyle = StyleContext.getDefaultStyleContext().getStyle(StyleContext.DEFAULT_STYLE);
        Style boldStyle = doc.addStyle("bold", defaultStyle);
        StyleConstants.setBold(boldStyle, true);

        scaledTextPane.setFont(new Font("Dialog", Font.PLAIN, 14));
        String boldText = "Four score and seven years ago ";
        String plainText = "our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.";
        try 
        {
            doc.insertString(doc.getLength(), boldText, boldStyle);
            doc.insertString(doc.getLength(), plainText, defaultStyle);
        } 
        catch (BadLocationException ble) 
        {
            System.err.println("Couldn't insert text into text pane.");
        }

        final JComboBox zoomCombo=new JComboBox(new String[] {"75%",
                "100%", "150%", "175%", "200%"});
        final JPanel panel = new JPanel()
        {
            protected void paintComponent(Graphics g)
            {
                super.paintChildren(g);
                scaledTextPane.paint(g);
            }
        };
       zoomCombo.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
              String s = (String) zoomCombo.getSelectedItem();
              s = s.substring(0, s.length() - 1);
              double scale = new Double(s).doubleValue() / 100;
              scaledTextPane.setScale(scale);
              panel.invalidate();
              panel.repaint();
            }
          });
        zoomCombo.setSelectedItem("100%");

        // Add content to the window.
        scaledTextPane.setBounds(0, 0, 450, 300);
        panel.setOpaque(true);
        panel.setBackground(Color.WHITE);
        frame.getContentPane().add(panel, BorderLayout.CENTER);
        frame.getContentPane().add(zoomCombo, BorderLayout.NORTH);
        frame.setSize(900, 300);

        //Display the window.
        frame.setVisible(true);
    }

    public static void main(String[] args) 
    {
        SwingUtilities.invokeLater(new Runnable() 
        {
            public void run() 
            {
                createAndShowGUI();
            }
        });
    }
}
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