如何设置JFrame大小以适应显示的JPanel CardLayout

Question

我有一个JFrame在CardLayout中包含一组JPanels。每个JPanel都有不同的大小，我希望JFrame适应当前显示的JPanel的大小(而不是JPanel适应JFrame的大小)。

我怎样才能做到这一点?

Answer 1

一般是:如果你有布局问题，总是用适当的LayoutManager解决它。永远不要调整组件的大小提示来达到你的目标。

在这种情况下，调整CardLayout特别容易。默认情况下，它计算它的presize到所有卡的presize的最大值。简单地子类化并实现返回当前可见卡片的presize(加上insets):

public static class MyCardLayout extends CardLayout {
    @Override
    public Dimension preferredLayoutSize(Container parent) {
        Component current = findCurrentComponent(parent);
        if (current != null) {
            Insets insets = parent.getInsets();
            Dimension pref = current.getPreferredSize();
            pref.width += insets.left + insets.right;
            pref.height += insets.top + insets.bottom;
            return pref;
        }
        return super.preferredLayoutSize(parent);
    }
    public Component findCurrentComponent(Container parent) {
        for (Component comp : parent.getComponents()) {
            if (comp.isVisible()) {
                return comp;
            }
        }
        return null;
    }
}

使用这个(借用@mKorbel的例子)，main方法清晰地缩小了:

private static void createAndShowUI() {
    final CardLayout cardLayout = new MyCardLayout();
    final JPanel cardHolder = new JPanel(cardLayout);
    final JFrame frame = new JFrame("MultiSizedPanels");
    JLabel[] labels = {
        new JLabel("Small Label", SwingConstants.CENTER),
        new JLabel("Medium Label", SwingConstants.CENTER),
        new JLabel("Large Label", SwingConstants.CENTER)};
    for (int i = 0; i < labels.length; i++) {
        int padding = 50 * (i + 1);
        Border lineBorder = BorderFactory.createCompoundBorder(
            BorderFactory.createLineBorder(Color.blue),
            BorderFactory.createEmptyBorder(padding, padding, padding, padding));
        labels[i].setBorder(lineBorder);
        JPanel containerPanel = new JPanel();
        containerPanel.add(labels[i]);
        cardHolder.add(containerPanel, String.valueOf(i));
    }
    JButton nextButton = new JButton("Next");
    nextButton.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            cardLayout.next(cardHolder);
            frame.pack();
        }
    });
    JPanel btnHolder = new JPanel();
    btnHolder.add(nextButton);
    frame.add(cardHolder, BorderLayout.CENTER);
    frame.add(btnHolder, BorderLayout.SOUTH);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setLocation(150, 150);
    frame.setVisible(true);
}

Answer 2

这是SSCCE。

1)对于连续的大小增加/减少，你应该寻找一些动画API。

或

2)如果没有任何后台任务输出到GUI，您可以在调整JFrame时暂停。在这种情况下，您可以通过将Thread#sleep(int)包装到Runnable线程中来延迟增加/减少。

3)注意(非OP)在EDT期间直接使用Thread#sleep(int)将冻结GUI，直到延迟结束。

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.Border;
//based on HFOE http://stackoverflow.com/questions/5414177/change-size-of-jpanel-using-cardlayout/5414770#5414770
public class MultiSizedPanels {
    private static void createAndShowUI() {
        final CardLayout cardLayout = new CardLayout();
        final JPanel cardHolder = new JPanel(cardLayout);
        final JFrame frame = new JFrame("MultiSizedPanels");
        JLabel[] labels = {
            new JLabel("Small Label", SwingConstants.CENTER),
            new JLabel("Medium Label", SwingConstants.CENTER),
            new JLabel("Large Label", SwingConstants.CENTER)};
        for (int i = 0; i < labels.length; i++) {
            int padding = 50;
            Dimension size = labels[i].getPreferredSize();
            size = new Dimension(size.width + 2 * (i + 1) * padding, size.height + 2 * (i + 1) * padding);
            labels[i].setPreferredSize(size);
            Border lineBorder = BorderFactory.createLineBorder(Color.blue);
            labels[i].setBorder(lineBorder);
            JPanel containerPanel = new JPanel();
            if (i == 1) {
                containerPanel.setPreferredSize(new Dimension(300, 200));
                containerPanel.add(labels[i], BorderLayout.CENTER);
                cardHolder.add(containerPanel, String.valueOf(i));
            } else if (i == 2) {
                containerPanel.setPreferredSize(new Dimension(600, 400));
                containerPanel.add(labels[i], BorderLayout.CENTER);
                cardHolder.add(containerPanel, String.valueOf(i));
            } else {
                containerPanel.setPreferredSize(new Dimension(800, 600));
                containerPanel.add(labels[i], BorderLayout.CENTER);
                cardHolder.add(containerPanel, String.valueOf(i));
            }
        }
        JButton nextButton = new JButton("Next");
        nextButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                cardLayout.next(cardHolder);
                Dimension dim = new Dimension();
                for (Component comp : cardHolder.getComponents()) {
                    if (comp.isVisible() == true) {
                        dim = comp.getPreferredSize();
                    }
                }
                frame.setPreferredSize(dim);
                java.awt.EventQueue.invokeLater(new Runnable() {
                    public void run() {
                        frame.pack();
                    }
                });
            }
        });
        JPanel btnHolder = new JPanel();
        btnHolder.add(nextButton);
        frame.add(cardHolder, BorderLayout.CENTER);
        frame.add(btnHolder, BorderLayout.SOUTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocation(150, 150);
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                createAndShowUI();
            }
        });
    }
}

Answer 3

我认为你可能有错误的布局管理器为你想做什么(撇开不谈，目前，我不确定你想做什么你说你想做的)。

我还没有找到关于我怀疑的文档，这是CardLayout将其所有子元素的大小调整为其容器的大小。我确实为它的"layoutContainer"方法找到了以下注释:

         * Each component in the <code>parent</code> container is reshaped
         * to be the size of the container, minus space for surrounding
         * insets, horizontal gaps, and vertical gaps.

我认为这是合理的行为，因为当用户遍历面板时，面板大小会跳跃，这对用户来说是非常烦人的。

如果这真的是你想要的行为，那么我认为你需要一个不同的布局管理器。由于这是一个不寻常的行为，一般来说，你可能找不到一个标准的一个来做这个特殊的"功能"，所以你可能不得不自己写。

Answer 4

Try this code this may help you.


protected void paintComponent(Graphics g) {
if (getModel().isArmed()) {
      g.setColor(Color.lightGray);
} else {
     g.setColor(getBackground());
}
g.fillOval(0, 0, getSize().width-1, getSize().height-1);
System.out.println("width is "+getSize().width+"height is "+getSize().height);
super.paintComponent(g);
}
protected void paintBorder(Graphics g) {
g.setColor(getForeground());
g.drawOval(0, 0, getSize().width-1, getSize().height-1);
}
Shape shape;
public boolean contains(int x, int y) {
if (shape == null || !shape.getBounds().equals(getBounds())) {
     shape = new Ellipse2D.Float(0, 0, getWidth(), getHeight());
}
return shape.contains(x, y);
}}