使用 LineBreakMeasurer 计算线条并更改字体大小

Question

我已经使用其他出色的答案来设计一种方法，该方法使用LineBreakMeasurer 返回JTextPane 的正确尺寸，给定它的内容和宽度。

问题在于，当我尝试不同的字体大小时，它会有点问题，我不知道为什么。它非常适用于 Arial 12，但不适用于 Arial 8 或 Arial 16，因为 nextLayout 计算长度错误。谁能告诉我为什么？

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.font.FontRenderContext;
import java.awt.font.LineBreakMeasurer;
import java.awt.font.TextLayout;
import java.text.AttributedCharacterIterator;
import java.text.AttributedString;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextPane;
import javax.swing.border.LineBorder;


public class Example1 {

static JFrame frame = new JFrame();
static JPanel bigPanel = new JPanel();
static JTextPane textPane[] = new JTextPane[10];



public static void main(String[] args) {

    frame.setLayout(new FlowLayout());
    frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

    for(int i=0 ; i<10 ; i++) {
        textPane[i] = new JTextPane();
        textPane[i].setFont(new Font("Arial", 0, 12+i ));
        textPane[i].setText("This is 10 characters of " + ((Integer)(10+i)).toString() + " points : a b c d e f g h i j");
        textPane[i].setPreferredSize(getTextDimension(textPane[i], 100));
        textPane[i].setBorder(new LineBorder(Color.BLACK));
        frame.add(textPane[i]);
    }

    frame.setSize(500, 500);
    frame.setVisible(true);

}

static private Dimension getTextDimension(JTextPane textPane, float width) {

    FontMetrics fm = textPane.getFontMetrics(textPane.getFont());
    int fontHeight = fm.getHeight()+ fm.getDescent();
    //int fontHeight = fm.getHeight();

    AttributedString text = new AttributedString(textPane.getText());
    FontRenderContext frc = textPane.getFontMetrics(textPane.getFont()).getFontRenderContext();
    AttributedCharacterIterator styledText = text.getIterator();
    LineBreakMeasurer measurer = new LineBreakMeasurer(styledText, frc);

    float wrappingWidth = width - textPane.getInsets().left - textPane.getInsets().right;

    int lines = 0;
     while (measurer.getPosition() < styledText.getEndIndex()) {
        TextLayout layout = measurer.nextLayout(wrappingWidth);
        lines++;
     }

     return new Dimension((int)Math.round(width), lines * fontHeight);
}

}

Answer 1

我通过在 AttributedString 实例化后添加以下行来修复字体大小问题：

AttributedString text = new AttributedString(textPane.getText());
text.addAttribute(TextAttribute.FONT, textPane.getFont());

我猜 Attributed String 需要定义字体，虽然我认为它是由 FontRenderContext 处理的，但至少对我来说不是。

Answer 2

我不确定您的getTextDimension() 有什么问题，但更可靠的方法是让文本组件进行计算。 How can I measure/calculate the size a Document needs to render itself?提供了几种观点

附录：这是@camickr 的TextPanePerfectSize 的变体。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.border.LineBorder;
import javax.swing.text.BadLocationException;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyledDocument;

/**
 * @see https://stackoverflow.com/a/15983197/230513
 * @see https://stackoverflow.com/a/3318949/230513
 */
public class Test {

    private static final int SIZE = 16;
    private static int size = SIZE;
    private static JTextPane textPane[] = new JTextPane[SIZE];

    public static void main(String[] args) {
        final JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel buttonPanel = new JPanel();
        buttonPanel.add(new JButton(new AbstractAction("Update") {
            @Override
            public void actionPerformed(ActionEvent e) {
                for (JTextPane jtp : textPane) {
                    StyledDocument doc = (StyledDocument) jtp.getDocument();
                    SimpleAttributeSet style = new SimpleAttributeSet();
                    StyleConstants.setFontFamily(style, "Serif");
                    StyleConstants.setFontSize(style, size++);
                    try {
                        doc.insertString(doc.getLength(), " one two three", style);
                        Dimension d = jtp.getPreferredSize();
                        Rectangle r = jtp.modelToView(jtp.getDocument().getLength());
                        d.height = r.y + r.height;
                        jtp.setPreferredSize(d);
                    } catch (BadLocationException ex) {
                        ex.printStackTrace(System.err);
                    }
                    frame.pack();
                }
            }
        }));
        frame.add(buttonPanel, BorderLayout.NORTH);
        JPanel textPanel = new JPanel(new GridLayout(0, 4));
        for (int i = 0; i < textPane.length; i++) {
            textPane[i] = new JTextPane();
            textPane[i].setText("Text pane number " + String.valueOf(i + 1));
            textPane[i].setBorder(new LineBorder(Color.BLACK));
            textPanel.add(textPane[i]);
        }
        frame.add(new JScrollPane(textPanel));
        frame.pack();
        frame.setVisible(true);
    }
}