Javadrone - 无法从 Parrot AR.Drone 2.0 获取图像

Posted 2023-02-22

【中文标题】Javadrone - 无法从 Parrot AR.Drone 2.0 获取图像

【英文标题】：Javadrone - Unable to get image from Parrot AR.Drone 2.0

【发布时间】：2015-07-23 16:18:42

【问题描述】：

我正在开发一个应用程序来控制 Parrot Ar.Drone 2.0 使用 Javadrone API 和库。

我能够连接到无人机并使其成功起飞/降落。有 2 个 java 文件：DroneTestVideo.java、VideoPanel.java。

DroneTestVideo.java文件负责连接无人机并获取数据，VideoPanel.java文件作为设置图像。

Javadrone API可以下载here。

但是，我不知道为什么我无法从无人机获取实时图像。它只是给我一个黑屏，上面写着：

“没有视频连接”

这是我的代码：

DroneTestVideo.java

package dronetest;

import com.codeminders.ardrone.ARDrone;
import com.codeminders.ardrone.ARDrone.VideoChannel;
import com.codeminders.ardrone.DroneStatusChangeListener;
import com.codeminders.ardrone.NavData;
import com.codeminders.ardrone.NavDataListener;
import java.io.IOException;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class DroneTestVideo extends javax.swing.JFrame implements DroneStatusChangeListener, NavDataListener

    private static final long CONNECT_TIMEOUT = 10000L;
    private ARDrone drone;
    private final VideoPanel video = new VideoPanel();

    public DroneTestVideo() 
        initComponents();
        initDrone();
        videoPanel.add(video);
        takeoff();
    

    private void initDrone() 
        try
            drone = new ARDrone();
            drone.addStatusChangeListener(this);
            drone.addStatusChangeListener(new DroneStatusChangeListener() 
                public void ready() 
                    org.apache.log4j.Logger.getLogger(getClass().getName()).debug("updateLoop::ready()");
                
            );
            System.err.println("Configure");
            drone.selectVideoChannel(ARDrone.VideoChannel.HORIZONTAL_ONLY);
            drone.setCombinedYawMode(true);
            drone.enableAutomaticVideoBitrate();
            System.err.println("Connecting to the drone");
            drone.connect();
            drone.waitForReady(CONNECT_TIMEOUT);
            drone.clearEmergencySignal();
            System.err.println("Connected to the drone");

         catch (IOException ex) 
            Logger.getLogger(DroneTestVideo.class.getName()).log(Level.SEVERE, null,ex);
        
        drone.addNavDataListener(this);
        video.setDrone(drone);
    

    private void takeoff()
    
        try 
            System.err.println("**********\nTRIM\n**********");
            drone.trim();
            Thread.sleep(2000);

            System.err.println("**********\nTAKEOFF\n**********");
            drone.takeOff();
            Thread.sleep(7000);

            drone.land();
         catch (IOException ex) 
            Logger.getLogger(DroneTestVideo.class.getName()).log(Level.SEVERE, null, ex);
         catch (InterruptedException ex) 
            Logger.getLogger(DroneTestVideo.class.getName()).log(Level.SEVERE, null, ex);
        
    

    public static void main(String args[]) 
        java.awt.EventQueue.invokeLater(new Runnable() 
            public void run() 
                new DroneTestVideo().setVisible(true);
            
        );
    

VideoPanel.java

package dronetest;

import com.codeminders.ardrone.ARDrone;
import com.codeminders.ardrone.DroneVideoListener;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;

public class VideoPanel extends javax.swing.JPanel implements DroneVideoListener

    private AtomicReference<BufferedImage> image = new AtomicReference<BufferedImage>();
    private AtomicBoolean preserveAspect = new AtomicBoolean(true);
    private BufferedImage noConnection = new BufferedImage(320, 240, BufferedImage.TYPE_INT_RGB);

    public VideoPanel() 
        initComponents();
        Graphics2D g2d = (Graphics2D) noConnection.getGraphics();
        Font f = g2d.getFont().deriveFont(24.0f);
        g2d.setFont(f);
        g2d.drawString("No video connection", 40, 110);
        image.set(noConnection);
    

    public void setDrone(ARDrone drone) 
        drone.addImageListener(this);
        System.err.println("setDrone function here!");
    

    public void setPreserveAspect(boolean preserve) 
        preserveAspect.set(preserve);
    

    public void frameReceived(BufferedImage im) 
        image.set(im);
        repaint();
    

    public void paintComponent(Graphics g) 
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        int width = getWidth();
        int height = getHeight();
        drawDroneImage(g2d, width, height);
    

    private void drawDroneImage(Graphics2D g2d, int width, int height) 
        BufferedImage im = image.get();
        if (im == null) 
            return;
        
        int xPos = 0;
        int yPos = 0;
        if (preserveAspect.get()) 
            g2d.setColor(Color.BLACK);
            g2d.fill3DRect(0, 0, width, height, false);
            float widthUnit = ((float) width / 4.0f);
            float heightAspect = (float) height / widthUnit;
            float heightUnit = ((float) height / 3.0f);
            float widthAspect = (float) width / heightUnit;

            if (widthAspect > 4) 
                xPos = (int) (width - (heightUnit * 4)) / 2;
                width = (int) (heightUnit * 4);
             else if (heightAspect > 3) 
                yPos = (int) (height - (widthUnit * 3)) / 2;
                height = (int) (widthUnit * 3);
            
        
        if (im != null) 
            g2d.drawImage(im, xPos, yPos, width, height, null);
        
    

【参考方案1】：

您没有更新屏幕，因此不会在 VideoPanel 中调用对 drawDroneImage 的新调用。

您应该设置一个循环来刷新 JPanel（称为 repaint()）。

此外，您还需要实施 DoubleBuffering Strategies 以获得更顺畅的图像事务。

【讨论】：

我想我确实更新了我的屏幕，正如你在 public void frameReceived(BufferedImage im) 函数中看到的那样，我调用了“repaint()”函数。这就是假设的工作方式吗？