Listener from VisionThread? What do I put in this?

Technical Java
1

This is our first year of vision processing. I am trying to figure out what goes in for the “listener” portion for the VisionThread.


visionThread = new VisionThread(server, new GripPipeline(),?){
            if (!gripPipeline.filterContoursOutput().isEmpty()) {
                Rect r = Imgproc.boundingRect(gripPipeline.filterContoursOutput().get(0));
                synchronized (imgLock){
                    centerX = r.x + (r.width / 2);
                }
            }
        }

Please help!

2

The listener in the example is a lambda expression, or an “anonymous function”. Basically, a method that’s defined where it’s used. It’s similar to an anonymous class, but is more succinct.


visionThread = new VisionThread(camera, new GripPipeline(), pipeline -> {
  if (!gripPipeline.filterContoursOutput().isEmpty()) {
    Rect r = Imgproc.boundingRect(gripPipeline.filterContoursOutput().get(0));
    synchronized (imgLock){
      centerX = r.x + (r.width / 2);
    }
  }
});

can also be written as


visionThread = new VisionThread(camera, new GripPipeline(), new VisionRunner.Listener<GripPipeline>() {
  @Override
  public void copyPipelineOutputs(GripPipeline pipeline) {
    // same as the contents of the lambda above
  }
});
3

Thank you for your reply the only thing that doesn’t work is my camera is a camera server of type CameraServer. What do I do? Here is my complete Robot.java class code.


// RobotBuilder Version: 2.0
//
// This file was generated by RobotBuilder. It contains sections of
// code that are automatically generated and assigned by robotbuilder.
// These sections will be updated in the future when you export to
// Java from RobotBuilder. Do not put any code or make any change in
// the blocks indicating autogenerated code or it will be lost on an
// update. Deleting the comments indicating the section will prevent
// it from being updated in the future.


package org.usfirst.frc3534.DriveTest;

import org.opencv.core.Mat;
import org.opencv.core.Rect;
import org.opencv.imgproc.Imgproc;

import edu.wpi.cscore.CvSink;
import edu.wpi.cscore.CvSource;
import edu.wpi.cscore.UsbCamera;
import edu.wpi.cscore.UsbCameraInfo;
import edu.wpi.first.wpilibj.CameraServer;
import edu.wpi.first.wpilibj.IterativeRobot;
import edu.wpi.first.wpilibj.RobotDrive;
import edu.wpi.first.wpilibj.command.Command;
import edu.wpi.first.wpilibj.command.Scheduler;
import edu.wpi.first.wpilibj.livewindow.LiveWindow;
import edu.wpi.first.wpilibj.smartdashboard.SmartDashboard;
import edu.wpi.first.wpilibj.vision.VisionPipeline;
import edu.wpi.first.wpilibj.vision.VisionRunner;
import edu.wpi.first.wpilibj.vision.VisionThread;

import org.usfirst.frc3534.DriveTest.commands.AutonomousCommand;
import org.usfirst.frc3534.DriveTest.commands.GripPipeline;
import org.usfirst.frc3534.DriveTest.subsystems.*;

/**
 * The VM is configured to automatically run this class, and to call the
 * functions corresponding to each mode, as described in the IterativeRobot
 * documentation. If you change the name of this class or the package after
 * creating this project, you must also update the manifest file in the resource
 * directory.
 */
public class Robot extends IterativeRobot {
	private VisionThread visionThread;
	private GripPipeline gripPipeline;
	private double centerX = 0.0;
	private RobotDrive drive;
	
	private final Object imgLock = new Object();
	
    Command autonomousCommand;

    public static OI oi;
    public int counter;
    public CameraServer server;
    
    // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=DECLARATIONS
    public static DriveTrain driveTrain;

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=DECLARATIONS

    /**
     * This function is run when the robot is first started up and should be
     * used for any initialization code.
     */
    public void robotInit() {
    	
    	
    	
    	visionThread = new VisionThread(camera, new GripPipeline(), pipeline -> {
    		  if (!gripPipeline.filterContoursOutput().isEmpty()) {
    		    Rect r = Imgproc.boundingRect(gripPipeline.filterContoursOutput().get(0));
    		    synchronized (imgLock){
    		      centerX = r.x + (r.width / 2);
    		    }
    		  }
    		});
    	
    
    	visionThread.start();
        
        drive = new RobotDrive(1, 2);
        
    	RobotMap.init();
        // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=CONSTRUCTORS
        driveTrain = new DriveTrain();
        
    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=CONSTRUCTORS
        // OI must be constructed after subsystems. If the OI creates Commands
        //(which it very likely will), subsystems are not guaranteed to be
        // constructed yet. Thus, their requires() statements may grab null
        // pointers. Bad news. Don't move it.
        oi = new OI();
        
        server = CameraServer.getInstance();
        server.setSize(50);
        //the camera name (ex "cam0") can be found through the roborio web interface
        server.startAutomaticCapture();
        
        // instantiate the command used for the autonomous period
        // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=AUTONOMOUS

        autonomousCommand = new AutonomousCommand();
        

        
        
        
        	
    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=AUTONOMOUS
    }

    /**
     * This function is called when the disabled button is hit.
     * You can use it to reset subsystems before shutting down.
     */
    public void disabledInit(){

    }

    public void disabledPeriodic() {
        Scheduler.getInstance().run();
    }

    public void autonomousInit() {
        // schedule the autonomous command (example)
        if (autonomousCommand != null)autonomousCommand.start();
    }

    /**
     * This function is called periodically during autonomous
     */
    public void autonomousPeriodic() {
        Scheduler.getInstance().run();
        log();
    }

    public void teleopInit() {
        // This makes sure that the autonomous stops running when
        // teleop starts running. If you want the autonomous to
        // continue until interrupted by another command, remove
        // this line or comment it out.
        if (autonomousCommand != null) autonomousCommand.cancel();
    }

    /**
     * This function is called periodically during operator control
     */
    public void teleopPeriodic() {
        Scheduler.getInstance().run();
        log();
    }

    /**
     * This function is called periodically during test mode
     */
    public void testPeriodic() {
        LiveWindow.run();
        log();
    }
    private void log(){
    	counter++;
    	
    	if(counter >= 5){
    		SmartDashboard.putNumber("Left Encoder Count", driveTrain.getLtEncoderPosition());
        	SmartDashboard.putNumber("Right Encoder Count", driveTrain.getRtEncoderPosition());
        	SmartDashboard.putNumber("Encoder Difference", driveTrain.getEncoderDifference());
        	SmartDashboard.putNumber("Rt Value", driveTrain.getRtValue());
        	SmartDashboard.putNumber("Correction Value", driveTrain.getCorrection());
    		
    		counter = 0;
    }
    }
}
4

Where did you initiate camera? I don’t see an object with that name in the variable declaring section?

5

Don’t copy-paste code that someone gives as an example and expect it to work.

And definitely don’t copy and paste it into a program and then ask someone if it works before you even try to run it. It’s lazy and very few people will be willing to help you.

6

I know. I am asking what to do to change the code from CameraServer to UsbCamera so it works.

7

Have you read the screensteps page?

8

I have seen this and read this multiple times today but, I just looked and found what I was looking for


UsbCamera camera = CameraServer.getInstance().startAutomaticCapture();

duh!
thank you guys!

9