JScrollPane 内の Java グリッド レイアウトで多数の画像サムネイルを効率的に表示するにはどうすればよいですか?

グリッド内のレイアウトに画像サムネイルを追加する方法

この質問では、JScrollPane 内に一連の画像サムネイルを保持する SpringLayout グリッドを調べます。具体的には、写真のリストのサイズが大きくなる可能性がある場合に、レイアウトをどのように処理するかです。

したがって、基本的には、スクロール ペイン (一般にビューとして知られる) 内に存在する何らかのコンテナが必要です。これに画像を追加する必要があります。

次の Java コード例では、写真は JPanel 上に存在し、JScrollPane にあります。

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
インポートjava.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt. image.BufferedImage;
インポートjava.io.File;
import java.io.FileFilter;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
インポートjavax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

パブリッククラス ImageGrid {

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

public ImageGrid() {
    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.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        }
    });
}

public class TestPane extends JPanel {

    private JPanel imagesPane;

    public TestPane() {
        setLayout(new BorderLayout());
        imagesPane = new JPanel(new WrapLayout());
        add(new JScrollPane(imagesPane));
        JButton scan = new JButton("Scan");
        scan.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String path = "C:\Users\shane\Dropbox\Ponies";
                File[] files = new File(path).listFiles(new FileFilter() {
                    @Override
                    public boolean accept(File pathname) {
                        String name = pathname.getName().toLowerCase();
                        return pathname.isFile() && (name.endsWith(".png")
                                || name.endsWith(".jpg")
                                || name.endsWith(".gif"));
                    }
                });
                imagesPane.removeAll();
                for (File file : files) {
                    try {
                        ImagePane pane = new ImagePane(file);
                        imagesPane.add(pane);
                    } catch (Exception exp) {
                        exp.printStackTrace();
                    }
                }
                imagesPane.revalidate();
                imagesPane.repaint();
            }
        });
        add(scan, BorderLayout.SOUTH);
    }
}

public class ImagePane extends JPanel {

    private Image img;

    public ImagePane(File source) throws IOException {
        img = ImageIO.read(source);
        if (img.getWidth(this) > 200 || img.getHeight(this) > 200) {
            int width = img.getWidth(this);
            int height = img.getWidth(this);
            float scaleWidth = 200f / width;
            float scaleHeight = 200f / height;
            if (scaleWidth > scaleHeight) {
                width = -1;
                height = (int)(height * scaleHeight);
            } else {
                width = (int)(width * scaleWidth);
                height = -1;
            }
            img = img.getScaledInstance(width, height, Image.SCALE_SMOOTH);
        }
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(200, 200);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g.create();
        if (img != null) {

// int width = img.getWidth();
// int height = img.getHeight();
// floatscale = 1f;
// AffineTransform at = new AffineTransform();
// at.translate(
// (getWidth() / 2) - ((img.getWidth() * スケール) / 2),
// (getHeight() / 2) - ((img.getHeight() * スケール) / 2));
// at.scale(scale,scale);
// g2d.setTransform(at);

            g2d.drawImage(img, 0, 0, this);
        }
        g2d.dispose();
    }
}

/**
 * FlowLayout subclass that fully supports wrapping of components.
 */
public class WrapLayout extends FlowLayout {

    private Dimension preferredLayoutSize;

    /**
     * Constructs a new
     * <code>WrapLayout</code> with a left alignment and a default 5-unit
     * horizontal and vertical gap.
     */
    public WrapLayout() {
        super();
    }

    /**
     * Constructs a new
     * <code>FlowLayout</code> with the specified alignment and a default 5-unit
     * horizontal and vertical gap. The value of the alignment argument must be
     * one of
     * <code>WrapLayout</code>,
     * <code>WrapLayout</code>, or
     * <code>WrapLayout</code>.
     *
     * @param align the alignment value
     */
    public WrapLayout(int align) {
        super(align);
    }

    /**
     * Creates a new flow layout manager with the indicated alignment and the
     * indicated horizontal and vertical gaps.
     * <p>
     * The value of the alignment argument must be one of
     * <code>WrapLayout</code>,
     * <code>WrapLayout</code>, or
     * <code>WrapLayout</code>.
     *
     * @param align the alignment value
     * @param hgap the horizontal gap between components
     * @param vgap the vertical gap between components
     */
    public WrapLayout(int align, int hgap, int vgap) {
        super(align, hgap, vgap);
    }

    /**
     * Returns the preferred dimensions for this layout given the
     * <i>visible</i> components in the specified target container.
     *
     * @param target the component which needs to be laid out
     * @return the preferred dimensions to lay out the subcomponents of the
     * specified container
     */
    @Override
    public Dimension preferredLayoutSize(Container target) {
        return layoutSize(target, true);
    }

    /**
     * Returns the minimum dimensions needed to layout the <i>visible</i>
     * components contained in the specified target container.
     *
     * @param target the component which needs to be laid out
     * @return the minimum dimensions to lay out the subcomponents of the
     * specified container
     */
    @Override
    public Dimension minimumLayoutSize(Container target) {
        Dimension minimum = layoutSize(target, false);
        minimum.width -= (getHgap() + 1);
        return minimum;
    }

    /**
     * Returns the minimum or preferred dimension needed to layout the target
     * container.
     *
     * @param target target to get layout size for
     * @param preferred should preferred size be calculated
     * @return the dimension to layout the target container
     */
    private Dimension layoutSize(Container target, boolean preferred) {
        synchronized (target.getTreeLock()) {
            //  Each row must fit with the width allocated to the containter.
            //  When the container width = 0, the preferred width of the container
            //  has not yet been calculated so lets ask for the maximum.

            int targetWidth = target.getSize().

以上がJScrollPane 内の Java グリッド レイアウトで多数の画像サムネイルを効率的に表示するにはどうすればよいですか?の詳細内容です。詳細については、PHP 中国語 Web サイトの他の関連記事を参照してください。