GridBagLayout中的JPanel位置不正确 [英] Incorrect JPanel position in GridBagLayout

问题描述

im使用GridBag在JScrollPane中显示带有图像的一些JPanel. 当有3张或3张以上图像时，GridBagConstraints可以正常工作，但当我有1张或2张图像时，它们会与JScrollPane的中心对齐，而不是位于顶部(例如在画廊中) 这是我的代码:

im using GridBag to display some JPanels with images inside a JScrollPane. When there are 3 or more images the GridBagConstraints work ok but when i have 1 or 2, they get aligned to the center of the JScrollPane instead of being in their position in the top (like in a gallery) Here is my code:

JPanel jPanel1 = new JPanel();
GridBagLayout layout = new GridBagLayout();
jPanel1.setLayout(layout);
GridBagConstraints gbc = new GridBagConstraints();

JPanel photo = new JPanel();
Dimension d = new Dimension(100,100);
photo.setPreferredSize(d);
gbc.insets = new Insets(0,3,3,3);

gbc.gridx = i;
gbc.gridy = j;
jPanel1.add(photo, gbc);


jScrollPane1.setViewportView(jPanel1);

我已经省略了将图像分配给Jpanel图片的部分. 我希望JPanels在它们的位置保持静态，并且如果有可用空间，则不要对齐. 如果即时通讯不清楚，我可以上传一些快照. 谢谢！

I have omitted the part where i assign an image to the photo Jpanel. I want the JPanels to stay static in their places and do not align if there is free space. If im not being clear i can upload a few snaps. Thanks!

推荐答案

GridBagLayout将其组件围绕容器的中心布局，这是它的(有时是令人讨厌的)默认功能.

GridBagLayout layouts its components out around the center of the container, this is it's (and sometimes annoying) default functionality.

您可以尝试添加一个空的填充"组件(例如JLabel)，其中weightx=1和weighty=1的GridBagConstraints在容器中其他组件的右侧和下方.这将迫使它们到达容器的左上角...

You could try adding an empty "filler" component (say a JLabel) with the GridBagConstraints of weightx=1 and weighty=1 at a position right of and below the other components in the container. This will force them to the top/left corner of the container...

已更新...

居中/默认...

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class GridBagLayoutTest {

    public static void main(String[] args) {
        new GridBagLayoutTest();
    }

    public GridBagLayoutTest() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.setSize(600, 600);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;

            JLabel picture = new JLabel();
            try {
                picture.setIcon(new ImageIcon(ImageIO.read(new File("/path/to/your/picture"))));
            } catch (IOException ex) {
                ex.printStackTrace();
                picture.setText("Bad picture");
            }
            add(picture, gbc);
        }
    }        
}

已对齐...

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class GridBagLayoutTest {

    public static void main(String[] args) {
        new GridBagLayoutTest();
    }

    public GridBagLayoutTest() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.setSize(600, 600);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;

            JLabel picture = new JLabel();
            try {
                picture.setIcon(new ImageIcon(ImageIO.read(new File("/path/to/your/picture"))));
            } catch (IOException ex) {
                ex.printStackTrace();
                picture.setText("Bad picture");
            }
            add(picture, gbc);

            JLabel filler = new JLabel();
            gbc.gridx = 1;
            gbc.gridy = 1;
            gbc.weightx = 1;
            gbc.weighty = 1;
            add(filler, gbc);
        }
    }        
}

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