Question

我正在尝试将JComponent函数作为库。它必须能够在其上显示保存的图像，这些图像将在生活在JScrollPane中的组件中显示。我还将添加删除图像的功能。我设法在组件上显示图像。我该怎么做呢？

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;

public class GalleryPanel extends JPanel 
{

private static final long serialVersionUID = 1L;
private int currentImage;
private JLabel[] images;
private final int MAX_IMAGES = 12;
private JScrollPane scrollPane;
private JPanel imageGallery;

public void init()
{   
    setLayout(new BorderLayout());
    images = new JLabel[MAX_IMAGES];
    imageGallery = new JPanel();
    imageGallery.setLayout(new GridLayout(12,1,10,10));

    scrollPane = new JScrollPane();
    scrollPane.setBackground(Color.RED);
    scrollPane.add(imageGallery);

    add(scrollPane, BorderLayout.CENTER);
    setBackground(Color.GRAY);
}


public void addImageToGallery(File file)
{
    if ( currentImage <= images.length - 1)
    {   
        BufferedImage bufImage = null;

        try
        {
            bufImage = ImageIO.read(file);  //tries to load the image
        }
        catch (Exception e)
        {
            System.out.println("Unable to load file " + file.toString());
        }

        Image resizedImage = bufImage.getScaledInstance(bufImage.getWidth()/6, bufImage.getHeight()/6, Image.SCALE_SMOOTH);
        ImageIcon icon = new ImageIcon(resizedImage);

        images[currentImage] = new JLabel(icon, JLabel.CENTER);

        scrollPane.add(images[currentImage]);
        images[currentImage].setSize(120, 100);
        scrollPane.add(images[currentImage]);

        currentImage++;

        //scrollPane.revalidate();
        //scrollPane.repaint();
    }
    else
    {
        throw new ArrayIndexOutOfBoundsException("The gallery is full");
    }
}


public final int getMaxImages()
{
    return MAX_IMAGES;
}


public Dimension getPreferredSize() 
{
      return new Dimension(300, 700);
}

}

Answer 1

scrollPane.add(images[currentImage]);
images[currentImage].setSize(120, 100);
scrollPane.add(images[currentImage]);

不要将组件直接添加到滚动窗格。

JScrollPane使用JViewport来保存要显示的组件。

因此，如果您想使用JList，请使用：

JList<Icon> list = new JList<Icon>();
JScrollPane scrollPane = new JScrollPane( list );
frame.add( scrollPane );

然后将Icon（不是JLabel）添加到JList。 JList已有自定义渲染器显示Icon。

阅读How to Use Lists上Swing教程中的部分，了解更多信息和工作示例。

本教程还有一个关于How to Use Scroll Panes的部分，你应该阅读。

Answer 2

我使用JImagePanel，JPanel，JList和JLabel

为我的CBIR java应用程序创建了ListCellRenderer

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package javax.swing;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.image.BufferedImage;
import java.util.Vector;
import javax.swing.border.LineBorder;

/**
 *
 * @author NiRRaNjAN RauT
 */
/**
* JImagePanel is used to display JList of BufferedImage
 * This class is extended to JPanel
*/
public class JImagePanel extends JPanel {

    /**
    * JList is used to display display BufferedImage
    */
    private JList imageList = null;
    /**
    * JScrollPane is used to add scroll bar to JList
    */
    JScrollPane scroll_pane = null;
    /**
    * Vector<BufferedImage> is used to store the BufferedImages
    */
    Vector<BufferedImage> listData = new Vector<BufferedImage>();

    /**
    * default constructor used to initialize JPanel
    */
    public JImagePanel() {
        this(null);
    }

     /**
     * @param data 
     * This parameterized constructor is used to
     * add the vector of BufferedImages to JList
     */
    public JImagePanel(Vector<BufferedImage> data) {
        setLayout(new BorderLayout());
        if(data != null) {
            listData = data;
        }
        imageList = new JList();
        imageList.setFixedCellHeight(160);
        imageList.setFixedCellWidth(160);
        if(!listData.isEmpty()) {
            imageList.setListData(listData);
        }
        imageList.setCellRenderer(new JCellRenderer());
        imageList.setAutoscrolls(true);
        imageList.setLayoutOrientation(JList.HORIZONTAL_WRAP);
        imageList.setVisibleRowCount(-1);
        scroll_pane = new JScrollPane(imageList);
        this.add(scroll_pane, BorderLayout.CENTER);
        this.setBorder(new LineBorder(Color.BLUE));
    }

    /**
     * @param selection 
     * The parameter selection is used to set multi selection on or off
     * When true, it allows to select multiple images in JList using
     * Ctrl key.
     */
    public void setMultiSelection(boolean selection) {
        if(selection) {
            imageList.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
        } else {
            imageList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        }
    }

    public int[] getSelectedIndices() {
        return imageList.getSelectedIndices();
    }

    public int getImageSize() {
        return imageList.getModel().getSize();
    }

    /**
     * @param image
     * This is used to add BufferedImage to JList
     * User can add new images to JList at runtime.
     */
    public void addImageToList(BufferedImage image) {
        listData.add(image);
        imageList.setListData(listData);
    }

    /**
     * The method is used to clear the old list data.
     * It sets the list data to empty list.
     */
    public void clear() {
        listData.clear();
        imageList.setListData(listData);
    }

    /**
     * @param data
     * This method is used to set list data to JList
     * The data should be Vector of BufferedImage
     */
    public void setListData(Vector<BufferedImage> data) {
        if(data == null || data.isEmpty()) {
            System.err.println("Empty Data");
            return;
        }
        listData = data;
        imageList.setListData(listData);
    }

}

对于此Panel ListCellRenderer组件，需要在下面给出。

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package javax.swing;

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.border.EmptyBorder;

/**
 *
 * @author NiRRaNjAN RauT
 */
/**
* JCellRenderer is extended to JLabel
* It is used to display the image on JList by implementing ListCellRenderer
*/
public class JCellRenderer extends JLabel implements ListCellRenderer  {

    /**
     * The width and height is used to set size of a JLabel.
     * It is default set to 200 * 200
     */
    private static final int width = 140, height = 140;

    /**
     * default constructor used to set size of JLabel and set Border to JLabel.
     */
    public JCellRenderer() {
        setSize(width, height);
        setOpaque(true);
        setBorder(new EmptyBorder(10, 10, 10, 10));
    }

    /**
     * @return Component
     * it returns JLabel for a cell.
     * The image from JList is set as icon on JLabel so that it displays the image as a JList item.
     */

    @Override
    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
        try {
            if(value instanceof BufferedImage) {
                BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
                Graphics2D g = image.createGraphics();
                g.drawImage((BufferedImage) value, 0, 0, width, height, null);
                g.dispose();
                setIcon(new ImageIcon(image));
            }
            if(isSelected) {
                setBackground(Color.DARK_GRAY);
            } else {
                setBackground(Color.LIGHT_GRAY);
            }
        } catch(Exception ex) {
            System.err.println("" + ex.getMessage());
        }
        return this;
    }
}

并且这是如何使用它。

JFrame frame = new JFrame("Image Panel Demo");
frame.setResizable(true);
frame.setSize(500, 500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JImagePanel panel = new JImagePanel();
panel.setMultiSelection(true);
frame.setLayout(new BorderLayout());
frame.add(panel, BorderLayout.CENTER);
frame.setVisible(true);
try {
    File files[] = new File("/SOFTWARES/NETBEANS_PROJECTS/BE/S_CBIR/dataset").listFiles();
    for(File file : files) {
        BufferedImage image = ImageIO.read(file);
        panel.addImageToList(image);
    }
} catch (Exception e) {
    e.printStackTrace(System.err);
}

希望它能提供帮助。

Swing JScrollPane库实现

2 个答案: