グリッド內(nèi)のレイアウトに畫(huà)像サムネイルを追加する方法

この質(zhì)問(wèn)では、JScrollPane 內(nèi)に一連の畫(huà)像サムネイルを保持する SpringLayout グリッドを調(diào)べます。具體的には、寫(xiě)真のリストのサイズが大きくなる可能性がある場(chǎng)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) 內(nèi)に存在する何らかのコンテナが必要です。これに畫(huà)像を追加する必要があります。

次の Java コード例では、寫(xiě)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 內(nèi)の Java グリッド レイアウトで多數(shù)の畫(huà)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(xì)內(nèi)容です。詳細(xì)については、PHP 中國(guó)語(yǔ) Web サイトの他の関連記事を參照してください。