java - 在另一个 JFrame 上显示 JPanel

Question

当前状态: 我有一个包含复杂组件(我自己编写的 3D Canvas )的 JPanel 对象。

问题: 现在有两个屏幕设备。我想用一个来控制，另一个只用来显示，就像 PowerPoint 一样。如何在另一个屏幕上有效地显示此 JPanel(静态 View 就足够了，但我希望它反射(reflect)控制屏幕上的变化？

我尝试过的: 我尝试每 200 毫秒将静态图片绘制到另一个 JPanel。

            Graphics2D g2 = (Graphics2D) contentPanel.getGraphics();
            g2.translate(x, y);
            g2.scale(scale, scale); 
            displayPanel.paintAll(g2);

注意:contentPanel在显示屏的一个JFrame中，displayerPanel是我要复制的面板

但是我遇到一个问题，显示屏幕闪烁严重到让我无法接受...是我CPU的问题还是显卡的问题？或者这些是我可以使用的任何有效方法吗？请帮忙，非常感谢!

这是 MCVE(抱歉，这是我第一次在 stackoverflow 中提问，但你的帮助让我很感动!再次感谢!)

import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.util.Timer;

public class DisplayWindow {

private static JFrame frame = new JFrame();
private static JPanel contentPanel = new JPanel();
private static JPanel displayPanel = null;
private static Timer timerDisplay = null;


static {
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(50, 50, 1366, 768);
    frame.getContentPane().add(contentPanel);
    frame.setVisible(true);
    if (timerDisplay == null) {
        timerDisplay = new java.util.Timer();
        timerDisplay.schedule(new DisplayAtFixedRate(), 1000, 250);
    }
}

public static void display(JPanel panel) {
    displayPanel = panel;
}

private static class DisplayAtFixedRate extends TimerTask {
    @Override
    public void run() {
        if (displayPanel != null && displayPanel.getWidth() != 0) {
            double windowWidth = frame.getWidth();
            double windowHeight = frame.getHeight();
            double panelWidth = displayPanel.getWidth();
            double panelHeight = displayPanel.getHeight();
            double scale = Math.min(windowWidth / panelWidth, windowHeight / panelHeight);
            int x = (int) (windowWidth - panelWidth * scale) / 2;
            int y = (int) (windowHeight - panelHeight * scale) / 2;

            Graphics2D g2 = (Graphics2D) contentPanel.getGraphics();
            g2.translate(x, y);
            g2.scale(scale, scale);
            displayPanel.paintAll(g2);
        }
    }
}

public static void main(String[] args) {
    JFrame controlFrame = new JFrame();
    controlFrame.setBounds(50, 50, 1366, 768);
    JPanel controlPanel = new JPanel();
    controlFrame.getContentPane().add(controlPanel, BorderLayout.CENTER);
    controlPanel.add(new JLabel("Hello Stackoverflow!"));
    controlFrame.setVisible(true);
    DisplayWindow.display(controlPanel);
}
}

Answer 1

给你举个例子:

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.WindowConstants;

public class PaintImage {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                startUI();
            }
        });
    }

    private static void startUI() {
        final JFrame mainFrm = new JFrame("Main");
        final JFrame paintFrame = new JFrame("Copy");
        mainFrm.add(new JScrollPane(new JTree()), BorderLayout.WEST);
        mainFrm.add(new JScrollPane(new JTextArea("Write your text here...")), BorderLayout.CENTER);
        mainFrm.pack();
        mainFrm.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        mainFrm.setLocationRelativeTo(null);

        final JLabel label = new JLabel("");
        paintFrame.add(label);
        paintFrame.setSize(mainFrm.getSize());
        paintFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        mainFrm.setVisible(true);
        paintFrame.setVisible(true);

        final Timer t = new Timer(200, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                final Image img = getScreenShot(mainFrm.getContentPane());
                label.setIcon(new ImageIcon(img));
            }
        });
        t.start();
    }

    public static BufferedImage getScreenShot(Component component) {

        final BufferedImage image = new BufferedImage(
                component.getWidth(),
                component.getHeight(),
                BufferedImage.TYPE_INT_RGB
                );
        // call the Component's paint method, using
        // the Graphics object of the image.
        component.paint( image.getGraphics() ); // alternately use .printAll(..)
        return image;
    }
}

getScreenShot 方法的来源是 here