如何将图像缩略图添加到网格中的布局？
这个问题着眼于 SpringLayout 网格，以在 JScrollPane 中保存一系列图像缩略图。具体来说，当照片列表的大小可能很大时如何处理布局。
所以基本上，您需要某种位于滚动窗格中的容器（通常称为视图）。您应该为此添加图像。
在以下 Java 代码示例中，照片位于 JPanel 上，并且位于 JScrollPane 中：
import java.awt.BorderLayout;
导入 java.awt.Component;
导入 java.awt.Container;
导入java.awt.Dimension;
导入 java.awt.EventQueue;
导入 java.awt.FlowLayout;
导入 java.awt.Graphics;
导入 java.awt.Graphics2D;
导入java.awt.Image;
导入 java.awt.Insets;
导入java.awt.event.ActionEvent;
导入 java.awt.event.ActionListener;
导入 java.awt.geom.AffineTransform;
导入 java.awt.image.BufferedImage;
导入 java. io.File;
导入 java.io.FileFilter;
导入 java.io.IOException;
导入javax.imageio.ImageIO;
导入 javax.swing.JButton;
导入 javax.swing.JFrame;
导入 javax.swing.JPanel;
导入 javax.swing.JScrollPane;
导入javax.swing.SwingUtilities;
导入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();
// 浮点数 = 1f;
// AffineTransform at = new AffineTransform();
// at.translate(
// (getWidth() / 2) - ((img.getWidth() * scale) / 2) ,
// (getHeight() / 2) - ((img.getHeight() * 比例) / 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().以上是如何在 JScrollPane 内的 Java 网格布局中高效显示大量图像缩略图？的详细内容。更多信息请关注PHP中文网其他相关文章！
