JPanel 位置和大小根据屏幕大小变化 [英] JPanel positions and sizes changes according to screensize

问题描述

程序根据屏幕分辨率或计算机大小运行.当我在具有特定显示器尺寸的计算机上运行它时，它会相应地改变.我的问题是 JPanel 或框架内任何对象的定位和大小，以适应屏幕尺寸的变化.

因此，每当我在任何不同尺寸的显示器上展示我的程序时，组件仍会按照我最初设计的方式进行组织和放置.但在这里我用一个名为 displayMenu 的 JPanel 来测试它.它显示了一个绿色的面板.

package saves.project;导入 com.sun.awt.AWTUtilities;导入 java.awt.*;导入 java.awt.image.BufferedImage;导入 java.io.*;导入 javax.swing.*;导入 javax.swing.border.*;导入 javax.swing.BorderFactory;导入 javax.imageio.ImageIO;公共类主页扩展 JFrame{尺寸屏幕尺寸 = Toolkit.getDefaultToolkit().getScreenSize();边框灰线 = BorderFactory.createLineBorder(Color.GRAY);;int width = screenSize.width, height = screenSize.height;公共主页()抛出 IOException{super("主页");显示菜单()；显示背景()；}public static BufferedImage resize(BufferedImage image, int width, int height) {BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);Graphics2D g2d = (Graphics2D) bi.createGraphics();g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));g2d.drawImage(image, 0, 0, width, height, null);g2d.dispose();返回bi;}public void displayBackground() 抛出 IOException{JPanel pBackground = new JPanel();pBackground.setSize(screenSize);pBackground.setLayout(new FlowLayout());添加(p背景)；BufferedImage header = ImageIO.read(new File("res\bg.jpg"));BufferedImage resizedImage = resize(header,width,height);ImageIcon image = new ImageIcon(resizedImage);JLabel lblheader = new JLabel(image, JLabel.CENTER);pBackground.add(lblheader);}公共无效显示菜单(){JPanel pTitle = new JPanel();pTitle.setLayout(null);pTitle.setBounds(width/3, (height/2)+20, width/2, height/2);pTitle.setBackground(Color.GREEN);添加(pTitle)；}公共无效 CreateAndShowGUI() {setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setExtendedState(JFrame.MAXIMIZED_BOTH);设置未装饰(真)；设置可见(真)；}}

另外，看起来我的背景没有完全分布在整个画面中.顶部有一条白线，其余部分是背景.我该怎么办?感谢帮助！

解决方案

跟进@MadProgrammer 评论:

你真的需要学习如何使用布局管理器.设置大小不是可行的方法，因为它们在不同的机器上会有不同的表现.

关于布局管理器的一件重要事情是哪些布局尊重其内部组件的首选大小.不遵守尺寸的那些将拉伸组件.某些布局可能不会拉伸其组件，但会在主容器拉伸时将它们放置在开放空间内的默认位置.

为了获得理想的结果，有时还需要嵌套具有不同布局的容器，这可以利用两个或多个布局.

我知道这并不是您问题的真正答案，但我认为您仍然可以对您的问题以及如何通过使用布局管理器实现您的目标有所了解.

下面我只是简单地举例说明了一些主要布局管理器的不同性质.你可以玩弄它.注意主要的 JFrame 使用默认的 BorderLayout.我只将布局显式设置为 BorderLayout 以便您可以查看导致效果的布局.

另请参阅

import java.awt.BorderLayout;导入 java.awt.FlowLayout;导入 java.awt.GridBagLayout;导入 java.awt.GridLayout;导入 javax.swing.*;公共类 TestingLayoutManagers {私人 JPanel 北流布局面板；私人 JPanel southBorderLayoutPanel;私人 JPanel centerGridBagLayoutPanel；私人 JPanel westBoxLayoutPanel；私人 JPanel 东格布局面板；private final JButton northButton = new JButton("North Button");private final JButton southButton = new JButton("South Button");private final JButton centerButton = new JButton("Center Button");private final JButtoneastButton = new JButton("East Button");private final JButton menuButton1 = new JButton("Menu Item 1");private final JButton menuButton2 = new JButton("Menu Item 2");private final JButton menuButton3 = new JButton("Menu Item 3");private final JButton menuButton4 = new JButton("Menu Item 4");private final JButton menuButton5 = new JButton("Menu Item 5");公共测试布局管理器(){NorthernFlowLayoutPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));SouthBorderLayoutPanel = new JPanel(new BorderLayout());centerGridBagLayoutPanel = new JPanel(new GridBagLayout());EastGridLayoutPanel = new JPanel(new GridLayout(1, 1));Box box = Box.createVerticalBox();westBoxLayoutPanel = new JPanel();NorthernFlowLayoutPanel.add(northButton);NorthernFlowLayoutPanel.setBorder(BorderFactory.createTitledBorder("Flow Layout"));SouthBorderLayoutPanel.add(southButton);SouthBorderLayoutPanel.setBorder(BorderFactory.createTitledBorder("Border Layout"));centerGridBagLayoutPanel.add(centerButton);centerGridBagLayoutPanel.setBorder(BorderFactory.createTitledBorder("GridBag Layout"));eastGridLayoutPanel.add(eastButton);EastGridLayoutPanel.setBorder(BorderFactory.createTitledBorder("网格布局"));box.add(menuButton1);box.add(menuButton2);box.add(menuButton3);box.add(menuButton4);box.add(menuButton5);westBoxLayoutPanel.add(box);westBoxLayoutPanel.setBorder(BorderFactory.createTitledBorder("Box Layout"));JFrame frame = new JFrame("测试布局管理器");frame.setLayout(new BorderLayout());//这是默认布局frame.add(northFlowLayoutPanel, BorderLayout.PAGE_START);frame.add(southBorderLayoutPanel, BorderLayout.PAGE_END);frame.add(centerGridBagLayoutPanel, BorderLayout.CENTER);frame.add(eastGridLayoutPanel, BorderLayout.LINE_END);frame.add(westBoxLayoutPanel, BorderLayout.LINE_START);frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);框架.pack();frame.setLocationRelativeTo(null);frame.setVisible(true);frame.setExtendedState(JFrame.MAXIMIZED_BOTH);}公共静态无效主(字符串 [] args){SwingUtilities.invokeLater(() -> {尝试 {UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());} catch (ClassNotFoundException)|实例化异常|非法访问异常|UnsupportedLookAndFeelException e) {e.printStackTrace();}新的 TestingLayoutManagers();});}}

The program runs with its size according to screen resolution or size of the computer. When I run it in a computer with specific size of its monitor it will change accordingly. My problem is the positioning and size of a JPanel, or any object inside the frame, to adopt on the change of screen size.

So whenever I will present my program on any monitor with different sizes the components will still be organized and placed as what I've originally designed it. But here I'm testing it with one JPanel named displayMenu. In which it displays a panel colored in green.

package saves.project;

import com.sun.awt.AWTUtilities;
import java.awt.*;
import java.awt.image.BufferedImage;

import java.io.*;

import javax.swing.*;
import javax.swing.border.*;
import javax.swing.BorderFactory;

import javax.imageio.ImageIO;

public class Homepage extends JFrame{

Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();

Border grayline = BorderFactory.createLineBorder(Color.GRAY);;

int width = screenSize.width, height = screenSize.height;

public Homepage() throws IOException{

    super("Homepage");
    displayMenu();
    displayBackground();

}

public static BufferedImage resize(BufferedImage image, int width, int height) {

    BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
    Graphics2D g2d = (Graphics2D) bi.createGraphics();
    g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
    g2d.drawImage(image, 0, 0, width, height, null);
    g2d.dispose();
    return bi;

}

public void displayBackground() throws IOException{

    JPanel pBackground = new JPanel();
    pBackground.setSize(screenSize);
    pBackground.setLayout(new FlowLayout());
    add(pBackground);

    BufferedImage header = ImageIO.read(new File("res\bg.jpg"));
    BufferedImage resizedImage = resize(header,width,height);
    ImageIcon image = new ImageIcon(resizedImage);
    JLabel lblheader = new JLabel(image, JLabel.CENTER);
    pBackground.add(lblheader);

}

public void displayMenu() {

    JPanel pTitle = new JPanel();
    pTitle.setLayout(null);
    pTitle.setBounds(width/3, (height/2)+20, width/2, height/2);
    pTitle.setBackground(Color.GREEN);
    add(pTitle);

}

public void CreateAndShowGUI() {

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setExtendedState(JFrame.MAXIMIZED_BOTH);
    setUndecorated(true);
    setVisible(true);  

}

}

Also, it looks like my background was not totally spread throughout the frame. There is a white line on the top but the rest is the background. What should I gonna do? Thanks for help!

解决方案

Following up with @MadProgrammer comment:

You really need to learn how to use Layout Mangers. Setting sizes is not the way to go, as they will perform different on different machines.

One important thing to know about Layout Managers are which layouts respect the preferred sizes of its internal components. The ones that do not respect the sizes, will stretch the components. Some layouts may not stretch their components, but will position them in a default location within the open space, when the main container is stretched.

To get desired results, it is also sometimes necessary to nest containers with different layouts, this taking advantage of two or more layouts.

I know this isn't really much of an answer to your question, but I thought you may still gain some insight to your problem, and how you can achieve what you are trying to, with the use of Layout Managers.

Below I just made up a quick example of the different natures of some of the main Layout Managers. You can play around with it. Note the main JFrame is using the default BorderLayout. I only explicitly set the layout as BorderLayout so you can see which layout causes the effect.

Also have a look at Laying out Components Withing a Container to learn more about how to use different Layout Managers. Avoid using the null layouts and trying to position everything yourself. Let the layouts do it for you, as Swing was built to used with Layout Managers.

---

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridBagLayout;
import java.awt.GridLayout;

import javax.swing.*;

public class TestingLayoutManagers {

    private JPanel northFlowLayoutPanel;
    private JPanel southBorderLayoutPanel;
    private JPanel centerGridBagLayoutPanel;
    private JPanel westBoxLayoutPanel;
    private JPanel eastGridLayoutPanel;

    private final JButton northButton = new JButton("North Button");
    private final JButton southButton = new JButton("South Button");
    private final JButton centerButton = new JButton("Center Button");
    private final JButton eastButton = new JButton("East Button");

    private final JButton menuButton1 = new JButton("Menu Item 1");
    private final JButton menuButton2 = new JButton("Menu Item 2");
    private final JButton menuButton3 = new JButton("Menu Item 3");
    private final JButton menuButton4 = new JButton("Menu Item 4");
    private final JButton menuButton5 = new JButton("Menu Item 5");

    public TestingLayoutManagers() {
        northFlowLayoutPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
        southBorderLayoutPanel = new JPanel(new BorderLayout());
        centerGridBagLayoutPanel = new JPanel(new GridBagLayout());
        eastGridLayoutPanel = new JPanel(new GridLayout(1, 1));
        Box box = Box.createVerticalBox();
        westBoxLayoutPanel = new JPanel();

        northFlowLayoutPanel.add(northButton);
        northFlowLayoutPanel.setBorder(BorderFactory.createTitledBorder("Flow Layout"));

        southBorderLayoutPanel.add(southButton);
        southBorderLayoutPanel.setBorder(BorderFactory.createTitledBorder("Border Layout"));

        centerGridBagLayoutPanel.add(centerButton);
        centerGridBagLayoutPanel.setBorder(BorderFactory.createTitledBorder("GridBag Layout"));

        eastGridLayoutPanel.add(eastButton);
        eastGridLayoutPanel.setBorder(BorderFactory.createTitledBorder("Grid Layout"));

        box.add(menuButton1);
        box.add(menuButton2);
        box.add(menuButton3);
        box.add(menuButton4);
        box.add(menuButton5);
        westBoxLayoutPanel.add(box);
        westBoxLayoutPanel.setBorder(BorderFactory.createTitledBorder("Box Layout"));

        JFrame frame = new JFrame("Test Layout Managers");
        frame.setLayout(new BorderLayout());      // This is the deafault layout
        frame.add(northFlowLayoutPanel, BorderLayout.PAGE_START);
        frame.add(southBorderLayoutPanel, BorderLayout.PAGE_END);
        frame.add(centerGridBagLayoutPanel, BorderLayout.CENTER);
        frame.add(eastGridLayoutPanel, BorderLayout.LINE_END);
        frame.add(westBoxLayoutPanel, BorderLayout.LINE_START);

        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH);

    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            try {
                UIManager.setLookAndFeel(
                        UIManager.getSystemLookAndFeelClassName());
            } catch (ClassNotFoundException
                    | InstantiationException
                    | IllegalAccessException
                    | UnsupportedLookAndFeelException e) {
                e.printStackTrace();
            }

            new TestingLayoutManagers();
        });
    }
}

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