JTextComponent ：如何更新现有的 StyledDocument 元素

Question

我使用两个 DefaultStyledDocument 编写了两个窗格差异 class。

现在我想让用户就地更改用于显示删除和插入的颜色（以及粗体），无需重新比较或保留中间差异结果。

我面临的问题是 insertString 复制了属性，所以我不能事后只更新 Style 实例。

我尝试了 DefaultStyledDocument.setLogicalStyle(int, Style) 但视觉上没有任何变化。

您是否看到一种 (simple/cheap) 无需重新创建整个文档即可进行样式更新的方法？

Answer 1

逻辑样式适用于整个段落。据我所知，无法将样式应用于段落中的字符并让 Swing 自动侦听样式中的更改。

您可以做的是将 Style 用作常规 AttributeSet，然后使用 ElementIterator 扫描样式元素，因为 Style 的名称存储在 AttributeSet.NameAttribute 属性键下：

void updateHighlight(StyledDocument doc,
                     AttributeSet newStyle) {

    Object styleName = newStyle.getAttribute(AttributeSet.NameAttribute);

    ElementIterator i = new ElementIterator(doc);
    for (Element e = i.first(); e != null; e = i.next()) {
        AttributeSet attr = e.getAttributes();
        Object name = attr.getAttribute(AttributeSet.NameAttribute);
        if (styleName.equals(name)) {
            int start = e.getStartOffset();
            int end = e.getEndOffset();
            doc.setCharacterAttributes(start, end - start,
                newStyle, false);
        }
    }
}

是否符合“simple/cheap”由您决定。

这是一个演示：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;

import javax.swing.Action;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;

import javax.swing.text.AttributeSet;
import javax.swing.text.Element;
import javax.swing.text.ElementIterator;
import javax.swing.text.Style;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyleContext;
import javax.swing.text.StyledDocument;

public class StyleChanger {
    public static void main(String[] args) {
        EventQueue.invokeLater(() -> show());
    }

    private static final String HIGHLIGHT =
        StyleChanger.class.getName() + ".highlight";

    static void show() {
        JTextPane textPane = new JTextPane();

        Style normal = textPane.getStyle(StyleContext.DEFAULT_STYLE);
        Style highlight = textPane.addStyle(HIGHLIGHT, normal);
        StyleConstants.setBackground(highlight, Color.YELLOW);

        class Fragment {
            final AttributeSet style;
            final String text;

            Fragment(AttributeSet style,
                     String text) {
                this.style = style;
                this.text = text;
            }
        }

        Fragment[] fragments = {
            new Fragment(highlight, "Space"),
            new Fragment(normal, ": the final frontier.  These are the "),
            new Fragment(highlight, "voyages"),
            new Fragment(normal, " of the starship "),
            new Fragment(highlight, "Enterprise"),
            new Fragment(normal, ".  Its five-year "),
            new Fragment(highlight, "mission"),
            new Fragment(normal, ": to explore strange "),
            new Fragment(highlight, "new worlds"),
            new Fragment(normal, "; to seek out "),
            new Fragment(highlight, "new life"),
            new Fragment(normal, " and new civilizations; to "),
            new Fragment(highlight, "boldly go"),
            new Fragment(normal, " where no man has gone before!"),
        };

        for (Fragment fragment : fragments) {
            textPane.setCharacterAttributes(fragment.style, true);
            textPane.replaceSelection(fragment.text);
        }

        Action change = new AbstractAction("Change Highlight\u2026") {
            private static final long serialVersionUID = 1;

            @Override
            public void actionPerformed(ActionEvent event) {
                Color color = JColorChooser.showDialog(
                    textPane.getTopLevelAncestor(),
                    "Highlight Color",
                    textPane.getBackground());

                if (color != null) {
                    StyleConstants.setBackground(highlight, color);
                    updateHighlight(textPane.getStyledDocument(), highlight);
                }
            }
        };

        JButton changeButton = new JButton(change);

        JPanel buttonPane = new JPanel();
        buttonPane.add(changeButton);

        JFrame frame = new JFrame("Style Changer");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.getContentPane().add(new JScrollPane(textPane));
        frame.getContentPane().add(buttonPane, BorderLayout.PAGE_END);

        frame.setSize(450, 300);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private static void updateHighlight(StyledDocument doc,
                                        AttributeSet newStyle) {

        Object styleName = newStyle.getAttribute(AttributeSet.NameAttribute);

        ElementIterator i = new ElementIterator(doc);
        for (Element e = i.first(); e != null; e = i.next()) {
            AttributeSet attr = e.getAttributes();
            Object name = attr.getAttribute(AttributeSet.NameAttribute);
            if (styleName.equals(name)) {
                int start = e.getStartOffset();
                int end = e.getEndOffset();
                doc.setCharacterAttributes(start, end - start,
                    newStyle, false);
            }
        }
    }
}

JTextComponent ：如何更新现有的 StyledDocument 元素

JTextComponent : how to update an existing StyledDocument elements

java

swing

jtextcomponent