Copy JTextArea as "text/html" DataFlavor

Question

I have a JTextArea and I am using a Highlighter to apply some syntax highlighting to some of my text as per my SSCCE below:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;

public class SSCCE extends JFrame {
  public SSCCE() {
    final JTextArea aMain = new JTextArea();
    aMain.setFont(new Font("Consolas", Font.PLAIN, 11));
    aMain.setMargin(new Insets(5, 5, 5, 5));
    aMain.setEditable(false);
    add(aMain);

    aMain.setText("The quick brown fox jumped over the lazy dog.");
    Highlighter h = aMain.getHighlighter();
    try {
      h.addHighlight(10, 15, new DefaultHighlighter.DefaultHighlightPainter(new Color(0xFFC800)));
    }
    catch (BadLocationException e) { 
      e.printStackTrace(); 
    }

    aMain.getActionMap().put("Copy", new AbstractAction() {
      public void actionPerformed(ActionEvent e) {
        aMain.copy();
      }
    });
    aMain.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_C, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()), "Copy");

    setTitle("SSCCE");
    setSize(350, 150);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
    setVisible(true);
  }

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

When the user selects a portion of text and presses CTRL+C then I am calling the copy() method of the JTextArea class. This copies the text onto the system clipboard as Plain Text and I lose any highlighting I have applied to my text. I am looking for the ability to copy the style information which includes the highlights as either "text/html" or "text/rtf". I believe I need to use the Transferable and DataFlavor classes, but I am struggling putting something together - I don't know how to get the data from the JTextArea in the correct format to place onto the clipboard.

I am basically trying to copy the highlighting and then paste it into Microsoft Word or similar application with the highlighting intact. Is the style data available in the correct format or do I manually have to construct a HTML markup by enumerating all the highlights?

Answer 1

Okay, so basically, because the highlighter is just "painted" over the JTextArea and doesn't actually adjust the style of the text, you kind of need to do it all yourself

Basically you need to:

• Get a list of all the current highlights
• Extract the text from the document
• Wrap it html
• Create a suitable HTML based transferable
• Copy the html markup to the clipboard

Easy...

import java.awt.Color;
import java.awt.Font;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringBufferInputStream;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import static javax.swing.JFrame.EXIT_ON_CLOSE;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Highlighter;

public class SSCCE extends JFrame {

    public SSCCE() {
        final JTextArea aMain = new JTextArea();
        aMain.setFont(new Font("Consolas", Font.PLAIN, 11));
        aMain.setMargin(new Insets(5, 5, 5, 5));
        aMain.setEditable(false);
        add(aMain);

        aMain.setText("The quick brown fox jumped over the lazy dog.");
        Highlighter h = aMain.getHighlighter();
        try {
            h.addHighlight(10, 15, new DefaultHighlighter.DefaultHighlightPainter(new Color(0xFFC800)));
        } catch (BadLocationException e) {
            e.printStackTrace();
        }

        aMain.getActionMap().put("Copy", new AbstractAction() {
            public void actionPerformed(ActionEvent e) {
                Highlighter h = aMain.getHighlighter();
                Highlighter.Highlight[] highlights = h.getHighlights();
                StringBuilder sb = new StringBuilder(64);
                sb.append("<html><body>");
                boolean markedUp = false;
                for (Highlighter.Highlight highlight : highlights) {
                    int start = highlight.getStartOffset();
                    int end = highlight.getEndOffset();

                    try {
                        String text = aMain.getDocument().getText(start, end - start);

                        sb.append("<span style = 'background-color: #FFC800'>");
                        sb.append(text);
                        sb.append("</span>");
                        markedUp = true;
                    } catch (BadLocationException ex) {
                        ex.printStackTrace();
                    }
                }
                sb.append("</body></html>");
                if (markedUp) {
                    Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
                    clipboard.setContents(new HtmlSelection(sb.toString()), null);
                }
            }
        });
        aMain.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_C, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()), "Copy");

        setTitle("SSCCE");
        setSize(350, 150);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    }

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

    private static class HtmlSelection implements Transferable {

        private static List<DataFlavor> htmlFlavors = new ArrayList<>(3);

        static {

            try {
                htmlFlavors.add(new DataFlavor("text/html;class=java.lang.String"));
                htmlFlavors.add(new DataFlavor("text/html;class=java.io.Reader"));
                htmlFlavors.add(new DataFlavor("text/html;charset=unicode;class=java.io.InputStream"));
            } catch (ClassNotFoundException ex) {
                ex.printStackTrace();
            }

        }

        private String html;

        public HtmlSelection(String html) {
            this.html = html;
        }

        public DataFlavor[] getTransferDataFlavors() {
            return (DataFlavor[]) htmlFlavors.toArray(new DataFlavor[htmlFlavors.size()]);
        }

        public boolean isDataFlavorSupported(DataFlavor flavor) {
            return htmlFlavors.contains(flavor);
        }

        public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException {
            if (String.class.equals(flavor.getRepresentationClass())) {
                return html;
            } else if (Reader.class.equals(flavor.getRepresentationClass())) {
                return new StringReader(html);
            } else if (InputStream.class.equals(flavor.getRepresentationClass())) {
                return new StringBufferInputStream(html);
            }
            throw new UnsupportedFlavorException(flavor);
        }
    }
}

I've pasted this to a text editor and opened in a browser and pasted into to Word

The above is based on Copy jTable row with its grid lines into excel/word documents