将图像缩略图添加到网格中的布局？ [英] Add image thumbnails to a layout in a grid?
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问题描述
我有一个图像列表。我需要在框架中添加小缩略图。我目前拥有 SpringLayout 的框架。如何使用滚动窗格在某些网格中添加缩略图。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;真正的问题如何在 SpringLayout 中显示缩略图网格。
I have a list of images. I need to add as small thumbnails to a frame. I currently have frame with SpringLayout. How can add thumbnails in some grid like fashion with a scroll pane. The list of photos could be large, so I need a scroll pane. I don;t know how to handle this with SpringLayout. I know how to add thumbnails; the real question how can I show the grid of thumbnails in SpringLayout.
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();
}
}
推荐答案
所以基本上，你需要某种容器，它位于滚动窗格中（通常称为视图）。
So basically, you need some kind of container that lives in the scroll pane (commonly known as the view).
要添加图片，你需要添加图片。
To this you should add your images.
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;
}
}
}
此示例包含 WrapLayout 。缩放是为了提高速度和简单性，但使用的方法是不可行的，请查看这个用于更好的方法。
This example includes WrapLayout. The scaling is done for speed and simplicity, but the method used is unavisable, take a look at this for a better method.
我通常会在后台线程中加载和缩放图像，比如 SwingWorker ，但这是一个例子。
I would normally load and scale the images in a background thread, like a SwingWorker, but this is an example of the idea.
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