构建了一个包含三个面板的小型测试 SWING 应用程序。一个主 JPanel,其中包含两个较小的 JPanel。一个在左边(板面板),另一个在右边(侧面板)。通过调用 min、preferred 和 max size 方法,将两个内部面板设置为请求的特定大小。右侧面板中的按钮将父 JFrame 设置为不可调整大小。在将父框架设置为不可调整大小之前,一切看起来都很棒,这会导致(?!)调整框架和主面板的大小,使其变大。
寻找调整大小的原因,以及如何保持主面板和框架的大小以仅包含两个内部面板,一旦框架被卡住,就不再包含其他面板。
已突出显示面板边框并添加了绘制事件日志记录以调试大小问题。
感谢您的帮助和见解!
编辑: 这个问题出现在 JRE 8 中。在 JRE 9 中它消失了,但引入了缩放问题。整个应用程序在我的 4k 显示器上放大,运行 Windows 10。
package org.fubar;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class PanelTest {
private static final String appTitle = "JPanel Test by Fubar.org(c)";
public static JFrame myFrame = null;
public static JPanel mainPanel = null;
public static JPanel boardPanel = null;
public static JPanel sidePanel = null;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
System.out.println("Create and show GUI");
JFrame myFrame = new JFrame(appTitle);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainPanel = new MainPanel();
myFrame.add(mainPanel);
myFrame.pack();
centreWindow(myFrame);
myFrame.setVisible(true);
}
public static void centreWindow(Window frame) {
Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
int x = (int) ((dimension.getWidth() - frame.getWidth()) / 2);
int y = (int) ((dimension.getHeight() - frame.getHeight()) / 2);
frame.setLocation(x, y);
}
public static void barfSize(JPanel panel, String panelName) {
Dimension panelSize = panel.getSize();
System.out.println(String.format("%s size:(%d,%d);",panelName,panelSize.width,panelSize.height));
}
}
class MainPanel extends JPanel {
static final long serialVersionUID = 1;
public MainPanel() {
setBorder(BorderFactory.createLineBorder(Color.green));
setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
PanelTest.boardPanel = new BoardPanel();
PanelTest.boardPanel.setAlignmentY(TOP_ALIGNMENT);
add(PanelTest.boardPanel);
PanelTest.sidePanel = new SidePanel();
PanelTest.sidePanel.setAlignmentY(TOP_ALIGNMENT);
add(PanelTest.sidePanel);
}
public void paintComponent(Graphics gooey) {
super.paintComponent(gooey);
PanelTest.barfSize(this, "Main Panel");
}
}
class BoardPanel extends JPanel {
static final long serialVersionUID = 1;
public BoardPanel() {
setBorder(BorderFactory.createLineBorder(Color.red));
Dimension mySize = new Dimension(400,200);
setMinimumSize(mySize);
setPreferredSize(mySize);
setMaximumSize(mySize);
JLabel lblText = new JLabel("Board Panel");
add(lblText);
}
public void paintComponent(Graphics gooey) {
super.paintComponent(gooey);
PanelTest.barfSize(this, "Board Panel");
}
}
class SidePanel extends JPanel implements ActionListener {
static final long serialVersionUID = 1;
public SidePanel() {
setBorder(BorderFactory.createLineBorder(Color.blue));
Dimension mySize = new Dimension(200,200);
setMinimumSize(mySize);
setPreferredSize(mySize);
setMaximumSize(mySize);
JLabel lblText = new JLabel("Side Panel");
add(lblText);
JButton btnFreeze = new JButton("Freeze");
btnFreeze.setActionCommand("Freeze");
btnFreeze.setToolTipText("Click me to freeze frame");
btnFreeze.setBorderPainted(true);
btnFreeze.setEnabled(true);
btnFreeze.addActionListener(this);
add(btnFreeze);
}
public void actionPerformed(ActionEvent action) {
String command = action.getActionCommand();
if ( command == "Freeze") {
freezeFrame();
System.out.println("Froze frame.");
}
Dimension panelSize = getSize();
System.out.println(String.format("Side Panel size:(%d,%d);",panelSize.width,panelSize.height));
}
public void paintComponent(Graphics gooey) {
super.paintComponent(gooey);
PanelTest.barfSize(this, "Side Panel");
}
public void freezeFrame() {
JFrame topFrame = (JFrame) SwingUtilities.getWindowAncestor(this);
Dimension parentSize = this.getParent().getSize();
topFrame.setMaximumSize(parentSize);
topFrame.setResizable(false);
}
}
屏幕截图 1:
App before frame resize disabled
屏幕截图 2:
App after frame resize disabled
运行日志
Create and show GUI
Main Panel size:(602,202);
Side Panel size:(200,200);
Board Panel size:(400,200);
Main Panel size:(602,202);
Side Panel size:(200,200);
Board Panel size:(400,200);
Froze frame.
Side Panel size:(200,200);
Main Panel size:(618,218);
Side Panel size:(200,200);
Board Panel size:(400,200);
Main Panel size:(618,218);
Side Panel size:(200,200);
Board Panel size:(400,200);
最佳答案
如果您在首次创建 JFrame 时将其设置为 setResizable(false),则不会出现该问题。
JFrame myFrame = new JFrame(appTitle);
myFrame.setResizable(false);
关于java - 当父框架设置为不可调整大小时,JPanel 会调整大小,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47298042/