将图像缩略图添加到网格中的布局？
我有一个图像列表。 我需要添加到一个框架的小缩略图。 我目前有SpringLayout框架。 如何在滚动窗格中像时尚一样添加缩略图。 照片列表可能很大，所以我需要一个滚动窗格。 我不知道如何用SpringLayout来处理这个问题。 我知道如何添加缩略图; 真正的问题是如何在SpringLayout显示缩略图的网格。
import java.awt.Color; import java.awt.Container; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.SpringLayout; public class grid { /** * @param args */ public grid() { JFrame frame = new JFrame("Hello"); Container pane = frame.getContentPane(); pane.setBackground(Color.WHITE); SpringLayout layout = new SpringLayout(); pane.setLayout(layout); JPanel photoPanel = new JPanel(); JScrollPane photoScroll = new JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS); photoPanel.add(photoScroll); pane.add(photoPanel); layout.putConstraint(SpringLayout.WEST, photoPanel, 260, SpringLayout.WEST, pane); layout.putConstraint(SpringLayout.NORTH, photoPanel, 40, SpringLayout.SOUTH, pane); frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); frame.pack(); //frame.setSize(frame.getMaximumSize()); frame.setExtendedState(JFrame.MAXIMIZED_BOTH); frame.setLocationRelativeTo(null); frame.setResizable(true); frame.setVisible(true); } public static void main(String[] args) { // TODO Auto-generated method stub new grid(); } }
所以基本上，你需要一些生活在滚动窗格（通常称为视图）的容器。
为此，你应该添加你的图片。
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; import java.awt.Insets; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.io.File; import java.io.FileFilter; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.SwingUtilities; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class 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(); // float scale = 1f; // AffineTransform at = new AffineTransform(); // at.translate( // (getWidth() / 2) - ((img.getWidth() * scale) / 2), // (getHeight() / 2) - ((img.getHeight() * scale) / 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().width; if (targetWidth == 0) { targetWidth = Integer.MAX_VALUE; } int hgap = getHgap(); int vgap = getVgap(); Insets insets = target.getInsets(); int horizontalInsetsAndGap = insets.left + insets.right + (hgap * 2); int maxWidth = targetWidth - horizontalInsetsAndGap; // Fit components into the allowed width Dimension dim = new Dimension(0, 0); int rowWidth = 0; int rowHeight = 0; int nmembers = target.getComponentCount(); for (int i = 0; i < nmembers; i++) { Component m = target.getComponent(i); if (m.isVisible()) { Dimension d = preferred ? m.getPreferredSize() : m.getMinimumSize(); // Can't add the component to current row. Start a new row. if (rowWidth + d.width > maxWidth) { addRow(dim, rowWidth, rowHeight); rowWidth = 0; rowHeight = 0; } // Add a horizontal gap for all components after the first if (rowWidth != 0) { rowWidth += hgap; } rowWidth += d.width; rowHeight = Math.max(rowHeight, d.height); } } addRow(dim, rowWidth, rowHeight); dim.width += horizontalInsetsAndGap; dim.height += insets.top + insets.bottom + vgap * 2; // When using a scroll pane or the DecoratedLookAndFeel we need to // make sure the preferred size is less than the size of the // target containter so shrinking the container size works // correctly. Removing the horizontal gap is an easy way to do this. Container scrollPane = SwingUtilities.getAncestorOfClass(JScrollPane.class, target); if (scrollPane != null && target.isValid()) { dim.width -= (hgap + 1); } return dim; } } /* * A new row has been completed. Use the dimensions of this row * to update the preferred size for the container. * * @param dim update the width and height when appropriate * @param rowWidth the width of the row to add * @param rowHeight the height of the row to add */ private void addRow(Dimension dim, int rowWidth, int rowHeight) { dim.width = Math.max(dim.width, rowWidth); if (dim.height > 0) { dim.height += getVgap(); } dim.height += rowHeight; } } }
这个例子包括WrapLayout 。 缩放是为了速度和简单性而完成的，但所使用的方法是不可见的，请参阅此处以获得更好的方法。
我通常会在后台线程中像SwingWorker一样加载和缩放图像，但这只是一个例子。
这个最近被删除的关于同一主题的问题提示这个例子，它使用随机大小的合成图像来说明缩放到最大尺寸的特定SIZE的效果。
import java.awt.*; import java.awt.image.BufferedImage; import java.util.Random; import javax.swing.*; /** @see https://stackoverflow.com/a/15982915/230513 */ public class Thumbnails { private static final int SIZE = 128; private static final Random r = new Random(); // Get a randomly sized image static private Image getImage() { int w = r.nextInt(SIZE) + SIZE / 2; int h = r.nextInt(SIZE) + SIZE / 2; BufferedImage bi = new BufferedImage( w, h, BufferedImage.TYPE_INT_ARGB); Graphics2D g2d = bi.createGraphics(); g2d.setPaint(Color.lightGray); g2d.fillRect(0, 0, w, h); g2d.setColor(Color.black); String s = w + "\u00D7" + h; int x = (w - g2d.getFontMetrics().stringWidth(s)) / 2; g2d.drawString(s, x, 24); g2d.dispose(); return bi; } // Get a panel with an image scaled to SIZE in the largest dimension // https://stackoverflow.com/a/15961424/230513 private static JPanel getPanel() { Image original = getImage(); int w = original.getWidth(null); int h = original.getHeight(null); float scaleW = (float) SIZE / w; float scaleH = (float) SIZE / h; if (scaleW > scaleH) { w = -1; h = (int) (h * scaleH); } else { w = (int) (w * scaleW); h = -1; } Image scaled = original.getScaledInstance(w, h, Image.SCALE_SMOOTH); JPanel p = new JPanel(new GridLayout()){ @Override public Dimension getPreferredSize() { return new Dimension(SIZE, SIZE); } }; p.add(new JLabel(new ImageIcon(scaled))); p.setBorder(BorderFactory.createLineBorder(Color.red)); return p; } private static void createAndShowGUI() { JFrame f = new JFrame("PhotoAlbum55"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel panel = new JPanel(new GridLayout(6, 6)); for (int i = 0; i < 6 * 6; i++) { panel.add(getPanel()); } f.add(new JScrollPane(panel)); f.pack(); f.setSize(4 * SIZE, 4 * SIZE); f.setLocationRelativeTo(null); f.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { createAndShowGUI(); } }); } }
