Multi-line tooltip, dynamically

Imagine a component has a dynamic tooltip.

It may be quite long. In that case, the user wants it to be split into multiple lines. The end goal is to never cut a tooltip with a screen edge. For example, on screens with low resolution long tooltips may exceed the total screen width.

How can I achieve it?

Remember, the text is dynamic, I can't wrap it in <html></html> and scatter <br> tags here and there.

package demos.text.field;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.WindowConstants;
import java.awt.Container;

public class TextFieldDemo {
    public static void main(String[] args) {
        Container mainPanel = createMainPanel();
        JFrame frame = new JFrame("Text field demo");
        frame.setContentPane(mainPanel);
        frame.setLocationRelativeTo(null);
        frame.pack();
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    private static JPanel createMainPanel() {
        JPanel panel = new JPanel();
        panel.add(createTextField());
        return panel;
    }

    private static JTextField createTextField() {
        JTextField textField = new JTextField("Text field with a tooltip");
        textField.setToolTipText("A " + "very ".repeat(10) + "long tooltip that must be split");
        return textField;
    }
}

Java 8.

Solution

How about adding a JTextArea with JTextArea#setLineWrap(true) to the JToolTip? This JTextArea will automatically wrap the text if it exceeds the width set by JTextArea.html#setColumns(...).

import java.awt.*;
import java.awt.event.MouseEvent;
import java.util.Collections;
import java.util.Objects;
import java.util.Optional;
import javax.swing.*;

public class LineWrapToolTipTest {
  private Component makeUI() {
    String very = String.join(" ", Collections.nCopies(10, "very"));
    String txt = "A " + very + " long tooltip that must be line wrap";
    JButton b1 = new JButton("JToolTip(Default)");
    b1.setToolTipText(txt + ": 1");
    JButton b2 = makeButton("LineWrapToolTip short");
    b2.setToolTipText("short: 2");
    JButton b3 = makeButton("LineWrapToolTip long");
    b3.setToolTipText(txt + ": 3");
    JPanel p = new JPanel();
    p.add(b1);
    p.add(b2);
    p.add(b3);
    return p;
  }

  private static JButton makeButton(String title) {
    return new JButton(title) {
      private transient JToolTip tip;

      @Override public JToolTip createToolTip() {
        if (tip == null) {
          tip = new LineWrapToolTip();
          tip.setComponent(this);
        }
        return tip;
      }

      @Override public String getToolTipText(MouseEvent e) {
        String txt = super.getToolTipText(e);
        EventQueue.invokeLater(() ->
            Optional.ofNullable(SwingUtilities.getWindowAncestor(tip))
                .filter(w -> w.getType() == Window.Type.POPUP)
                .ifPresent(Window::pack));
        return txt;
      }
    };
  }

  public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      frame.getContentPane().add(new LineWrapToolTipTest().makeUI());
      frame.setSize(320, 240);
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
    });
  }
}

class LineWrapToolTip extends JToolTip {
  private final JTextArea textArea = new JTextArea(0, 20);
  private final JLabel label = new JLabel(" ");

  protected LineWrapToolTip() {
    super();
    textArea.setLineWrap(true);
    textArea.setWrapStyleWord(true);
    // textArea.setColumns(20);
    textArea.setOpaque(true);
    LookAndFeel.installColorsAndFont(
        textArea, "ToolTip.background", "ToolTip.foreground", "ToolTip.font");
    setLayout(new BorderLayout());
    add(textArea);
  }

  @Override public final void setLayout(LayoutManager mgr) {
    super.setLayout(mgr);
  }

  @Override public final Component add(Component comp) {
    return super.add(comp);
  }

  @Override public Dimension getPreferredSize() {
    // return getLayout().preferredLayoutSize(this);
    Dimension d = getLayout().preferredLayoutSize(this);
    label.setText(textArea.getText());
    Insets i = getInsets();
    Insets ti = textArea.getInsets();
    Insets tm = textArea.getMargin();
    int pad = i.left + i.right + ti.left + ti.right + tm.left + tm.right;
    d.width = Math.min(d.width, label.getPreferredSize().width + pad);
    return d;
  }

  @Override public void setTipText(String tipText) {
    String oldValue = textArea.getText();
    if (!Objects.equals(oldValue, tipText)) {
      textArea.setText(tipText);
      firePropertyChange("tiptext", oldValue, tipText);
      revalidate();
      repaint();
    }
  }

  @Override public String getTipText() {
    return Optional.ofNullable(textArea).map(JTextArea::getText).orElse(null);
  }
}