这是一个使用 WrapLayout 的示例，它似乎可以正常工作：
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import org.mcavallo.opencloud.Cloud;
import org.mcavallo.opencloud.Tag;
public class TestOpenCloud {
private static final String[] WORDS = { "art", "australia", "baby", "beach", "birthday", "blue", "bw", "california", "canada", "canon",
"cat", "chicago", "china", "christmas", "city", "dog", "england", "europe", "family", "festival", "flower", "flowers", "food",
"france", "friends", "fun", "germany", "holiday", "india", "italy", "japan", "london", "me", "mexico", "music", "nature",
"new", "newyork", "night", "nikon", "nyc", "paris", "park", "party", "people", "portrait", "sanfrancisco", "sky", "snow",
"spain", "summer", "sunset", "taiwan", "tokyo", "travel", "trip", "uk", "usa", "vacation", "water", "wedding" };
protected void initUI() {
JFrame frame = new JFrame(TestOpenCloud.class.getSimpleName());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel panel = new JPanel(new WrapLayout());
Cloud cloud = new Cloud();
final Random random = new Random();
for (String s : WORDS) {
for (int i = random.nextInt(50); i > 0; i--) {
cloud.addTag(s);
}
}
for (Tag tag : cloud.tags()) {
final JLabel label = new JLabel(tag.getName());
label.setOpaque(false);
label.setFont(label.getFont().deriveFont((float) tag.getWeight() * 10));
panel.add(label);
}
JScrollPane scrollPane = new JScrollPane(panel);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
frame.add(scrollPane);
frame.setSize(500, 550);
frame.setVisible(true);
Timer t = new Timer(1000, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
final JLabel label = new JLabel(WORDS[random.nextInt(WORDS.length)]);
label.setOpaque(false);
int fontSize = random.nextInt(20) + 8;
label.setFont(label.getFont().deriveFont((float) fontSize));
panel.add(label);
panel.revalidate();
panel.repaint();
}
});
t.start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new TestOpenCloud().initUI();
}
});
}
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 container 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) {
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;
}
}
}
