Get height of multi line text with fixed width to make dialog resize properly

问题

I want to create a dialog that contains some kind of text element (JLabel/JTextArea etc) that is multi lined and wrap the words. I want the dialog to be of a fixed width but adapt the height depending on how big the text is. I have this code:

import static javax.swing.GroupLayout.DEFAULT_SIZE;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class TextSizeProblem extends JFrame {
  public TextSizeProblem() {

    String dummyString = "";
    for (int i = 0; i < 100; i++) {
      dummyString += " word" + i;  //Create a long text
    }
    JLabel text = new JLabel();
    text.setText("<html>" + dummyString + "</html>");

    JButton packMeButton = new JButton("pack");
    packMeButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        pack();
      }
    });

    GroupLayout layout = new GroupLayout(this.getContentPane());
    getContentPane().setLayout(layout);
    layout.setVerticalGroup(layout.createParallelGroup()
        .addComponent(packMeButton)
        .addComponent(text)
    );
    layout.setHorizontalGroup(layout.createSequentialGroup()
        .addComponent(packMeButton)
        .addComponent(text, DEFAULT_SIZE, 400, 400) //Lock the width to 400
    );

    pack();
  }

  public static void main(String args[]) {
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        JFrame frame = new TextSizeProblem();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
      }
    });
  }
}

When running the program it looks like this:
_{(source: lesc.se)}

But I would like the dialog to look like this (as when you press the pack-button):
_{(source: lesc.se)}

I'm guessing that the problem is that the layout manager had not been able to determine the proper height of the text before displaying it to the screen. I have tried various validate(), invalidate(), validateTree() etc but have not succeed.

回答1:

Here is an adaptation of your code, doing what you want. But it needs a little trick to calculate the size of the label and set its preferred Size.

I found the solution here

import static javax.swing.GroupLayout.DEFAULT_SIZE;

import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;
import javax.swing.text.View;

public class TextSizeProblem extends JFrame {
    public TextSizeProblem() {

        String dummyString = "";
        for (int i = 0; i < 100; i++) {
            dummyString += " word" + i; // Create a long text
        }
        JLabel text = new JLabel();
        text.setText("<html>" + dummyString + "</html>");

        Dimension prefSize = getPreferredSize(text.getText(), true, 400);

        JButton packMeButton = new JButton("pack");
        packMeButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                pack();
            }
        });



        GroupLayout layout = new GroupLayout(this.getContentPane());
        getContentPane().setLayout(layout);
        layout.setVerticalGroup(layout.createParallelGroup().addComponent(packMeButton)
                .addComponent(text,DEFAULT_SIZE, prefSize.height, prefSize.height));
        layout.setHorizontalGroup(layout.createSequentialGroup().addComponent(packMeButton)
                .addComponent(text, DEFAULT_SIZE, prefSize.width, prefSize.width) // Lock the width to 400
                );

        pack();
    }

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new TextSizeProblem();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }

    private static final JLabel resizer = new JLabel();

    /**
     * Returns the preferred size to set a component at in order to render an html string. You can
     * specify the size of one dimension.
     */
    public static java.awt.Dimension getPreferredSize(String html, boolean width, int prefSize) {

        resizer.setText(html);

        View view = (View) resizer.getClientProperty(javax.swing.plaf.basic.BasicHTML.propertyKey);

        view.setSize(width ? prefSize : 0, width ? 0 : prefSize);

        float w = view.getPreferredSpan(View.X_AXIS);
        float h = view.getPreferredSpan(View.Y_AXIS);

        return new java.awt.Dimension((int) Math.ceil(w), (int) Math.ceil(h));
    }
}

回答2:

I think this is what you want:

JLabel label = new JLabel("<html><div style=\"width:200px;\">Lots of text here...</div></html>");
// add the label to some Container.

This will restrict the JLabel to being 200 pixels wide and automatically adjust the height to fit the text.

回答3:

I found a solution to my problem. By replacing the JLabel with a JTextArea:

JTextArea text = new JTextArea();
text.setText(dummyString);
text.setLineWrap(true);
text.setWrapStyleWord(true);

And calling pack() followed by an invocation to the layout manager to layout the components again followed by another pack:

pack();
layout.invalidateLayout(this.getContentPane());
pack();

This will cause the layout manager to adapt to the width.

The complete code:

import static javax.swing.GroupLayout.DEFAULT_SIZE;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class TextSizeProblem3 extends JFrame {
  public TextSizeProblem3() {

    String dummyString = "";
    for (int i = 0; i < 100; i++) {
      dummyString += " word" + i;  //Create a long text
    }
    JTextArea text = new JTextArea();
    text.setText(dummyString);
    text.setLineWrap(true);
    text.setWrapStyleWord(true);

    JButton packMeButton = new JButton("pack");
    packMeButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        pack();
      }
    });

    GroupLayout layout = new GroupLayout(this.getContentPane());
    getContentPane().setLayout(layout);
    layout.setVerticalGroup(layout.createParallelGroup()
        .addComponent(packMeButton)
        .addComponent(text)
    );
    layout.setHorizontalGroup(layout.createSequentialGroup()
        .addComponent(packMeButton)
        .addComponent(text, DEFAULT_SIZE, 400, 400) //Lock the width to 400
    );

    pack();
    layout.invalidateLayout(this.getContentPane());
    pack();
  }

  public static void main(String args[]) {
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        JFrame frame = new TextSizeProblem3();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
      }
    });
  }
}

(you can add some customization (border, color etc) so it looks just like the JLabel but I have omitted that)

来源：https://stackoverflow.com/questions/1048224/get-height-of-multi-line-text-with-fixed-width-to-make-dialog-resize-properly

标签

java

swing

layout-manager