java - 转到最后滚动的位置 java swing JScrollPane

Question

我有一个 JScrollPane，我在其中显示图像。相关的代码行是

ImageIcon ii = new ImageIcon(in);
scrollPane.setViewportView(new JLabel(ii)); 

此代码在单击按钮时被调用，它基本上加载相同的图像并稍作修改。

假设加载了一张图片并且用户滚动(水平和垂直)以转到某个位置。下次单击按钮并加载新图像时，滚动 Pane 会忘记先前滚动的位置并重新开始一切。

我想查看上次滚动位置的图像，直到发生另一次滚动。这可能吗？

编辑

代码如下:

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
import javax.swing.SwingConstants;
import javax.swing.border.EmptyBorder;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class TestScrollPane extends JFrame {
    /**
     * 
     */
    static BufferedImage in = null;
    private JPanel contentPane;
    static String imageLoc=null;
    static Point p= new Point(2,2);
    /**
     * Launch the application.
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        EventQueue.invokeLater(new Runnable() {

            public void run() {
                try {
                    TestScrollPane frame = new TestScrollPane();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */

    private String getAnewImage() throws IOException {
        return "/home/abc/test.jpg"; //change this
    }
    public TestScrollPane() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(0, 0, 1300, 1000);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        //all declarations go here
        final JScrollPane scrollPane = new JScrollPane();
        final JButton btnInput = new JButton("Test");
        btnInput.setVerticalAlignment(SwingConstants.TOP);
        btnInput.setFont(new Font("Dialog", Font.BOLD, 12));
        btnInput.setHorizontalAlignment(SwingConstants.LEFT);
        final JButton btnStart = new JButton("start");
        final JViewport jv= scrollPane.getViewport();

        // all dimensions go here
        scrollPane.setBounds(2, 2, 1150, 950);
        btnInput.setBounds(1160, 100, 90, 50);
        btnStart.setBounds(1160, 300, 90, 25);

        contentPane.add(scrollPane);


        jv.addChangeListener(new ChangeListener() {
            @Override
            public void stateChanged(ChangeEvent e) {
                p=jv.getViewPosition();
            }
        });



        btnInput.addActionListener(new ActionListener()  {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    in = ImageIO.read(new File(imageLoc));
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                ImageIcon ii = new ImageIcon(in);
                System.out.println("setting viewport to "+p);
                scrollPane.setViewportView(new JLabel(ii));
                scrollPane.getViewport().setViewPosition(p);
            }
        });

        contentPane.add(btnInput);


        btnStart.addActionListener(new ActionListener()  {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    imageLoc=getAnewImage();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                if (imageLoc==null)
                    return;
                else {

                    try {
                        in = ImageIO.read(new File(imageLoc));
                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }
                    ImageIcon ii = new ImageIcon(in);
                    scrollPane.setViewportView(new JLabel(ii));
                }

            }


        });


        contentPane.add(btnStart);


        }
    }

这是我用于测试的图像:: . Start 按钮加载新图像。在我滚动并单击“输入”按钮后，加载了另一个图像，但滚动 Pane 返回到左上角(原始位置)。

Answer 1

保存视口(viewport)的位置然后恢复它的位置:

Point p = scrollPane.getViewport().getViewPostion();
scrollPane.setViewportView(new JLabel(ii));
scrollPane.getViewport.setViewPosition( p );

编辑:

我将您的 SSCCE 更改为使用 ContainerListener 来重置视口(viewport) View 位置:

jv.addContainerListener( new ContainerAdapter()
{
    @Override
    public void componentAdded(ContainerEvent e)
    {
        scrollPane.getViewport().setViewPosition(p);
    }
});