java - Javadrone - Unable to get image from Parrot AR.Drone 2.0 -

i working on app control parrot ar.drone 2.0 using javadrone api , library.

i able connect drone , make take off/land successfully. there 2 java files : dronetestvideo.java, videopanel.java.

the dronetestvideo.java file responsible connecting drone , data, while videopanel.java file serves set images.

javadrone api can download here.

however, have no idea why i'failing live images drone. show me black screen words:

"no video connection"

here code:

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 drone");             drone.connect();             drone.waitforready(connect_timeout);             drone.clearemergencysignal();             system.err.println("connected 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);         }     } } 

you not updating screen, no new calls drawdroneimage called videopanel.

you should set loop refresh jpanel (call repaint()).

and more, need implement doublebuffering strategies smoother image transaction.