Я пытаюсь сделать рендер Render Mandelbrot Set с графическим интерфейсом, где вы можете нажать и перетащить, чтобы увеличить в определенной области. При запуске он выполняет начальные вычисления и отрисовку нормально, но когда вы пытаетесь щелкнуть и перетащить, чтобы увеличить масштаб, консоль говорит, что выполняет вычисления, но содержимое JFrame не обновляется.

Тем не менее, я даже не уверен, что он пересчитывает, потому что первоначальный расчет занимает около 8 секунд, но при нажатии / перетаскивании для увеличения это занимает около 6 мс.

Я разместил свой код ниже.

Класс комплексных чисел

public class Complex {
    private double real, imag;

    // Constructors
    public Complex(){
        real=0.0;
        imag=0.0;
    }

    public Complex(double real, double imag) {
        this.real=real;
        this.imag=imag;
    }

    // add given complex number to this one, returning the Complex result
    public Complex add(Complex other) {
        return new Complex(this.real+other.real, this.imag+other.imag);
    }

    // multiply given complex number by this one, returning the Complex result
    public Complex multiply(Complex other) {
        return new Complex((this.real*other.real)-(this.imag*other.imag), (this.imag*other.real)+(this.real*other.imag));
    }

    // get the magnitude of this complex number
    public double getMagnitude() {
        return Math.sqrt((real*real)+(imag*imag));
    }
}

Runnable MandelbrotTask Class

public class MandelbrotTask implements Runnable {
    private double x1, y1, x2, y2;
    private int startCol, endCol, startRow, endRow, maxIters;
    private int[][] iterCounts;

       public MandelbrotTask(int maxIters, double x1, double y1, double x2, double y2, int startCol, int endCol, int startRow, int endRow, int[][] iterCounts) {
            this.x1 = x1;
            this.y1 = y1;
            this.x2 = x2;
            this.y2 = y2;
            this.startCol = startCol;
            this.endCol = endCol;
            this.startRow = startRow;
            this.endRow = endRow;
            this.iterCounts = iterCounts;
            this.maxIters=maxIters;         
}

    @Override
    public void run() {
        for (int i = startRow; i < endRow; i++) {
            for (int j = startCol; j < endCol; j++) {
                Complex c = getComplex(i, j);
                int iterCount = countIters(c);
                iterCounts[i][j] = iterCount;
            }
        }
    }

    public Complex getComplex(int i, int j){
        //output image is 600 X 600 pixels
        double incrementX;
        double incrementY;
        if(x2!=x1){
            incrementX=(Math.abs(x2-x1)/600);
        }
        else{
            throw new ArithmeticException("Error: area=0");
        }
        if(y2!=y1){
            incrementY=(Math.abs(y2-y1)/600);
        }
        else{
            throw new ArithmeticException("Error: area=0");
        }

        return new Complex(x1+((double)i*incrementX), y1+((double)j*incrementY));
    }

    public int countIters(Complex c){
        Complex z=new Complex(0, 0);
        int iters=0;
        while(z.getMagnitude()<2 && iters<=maxIters){
            z=z.multiply(z).add(c);
            iters++;
        }
        return iters;
    }
}

Главный класс Мандельброта

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Scanner;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;

public class Mandelbrot {
    private static final int HEIGHT = 600;
    private static final int WIDTH = 600;
    private static final int maxIters=50000;

    private static Rectangle zoomBox;
    private static Point initialClick;
    private static JLabel content; //bufferedImage will be put into this JLabel
    private static int[][] iterCounts;
    private static BufferedImage bufferedImage; //rendering will be written to this bufferedImage
    private static JFrame frame;

    public static void main(String[] args) throws IOException {
        zoomBox=null;
        Scanner keyboard = new Scanner(System.in);

        double x1 = -2;
        double y1 = -2;
        double x2 = 2;
        double y2 = 2;
        /*System.out.print("Max iterations (16,581,375 supported): ");
        int maxIters=50000;
        if(maxIters>16581375){
            throw new UnsupportedOperationException("Error: Max Iterations: Overflow.");
        }
        System.out.print("Output filename: ");
        String fileName = keyboard.next();
        if(!fileName.endsWith(".png") && !fileName.endsWith(".PNG")){
            fileName=fileName + ".png";
        }*/

        // TODO: create the rendering, save it to a file
        iterCounts=new int[WIDTH][HEIGHT];
        recalculate(x1, y1, x2, y2, iterCounts);

        bufferedImage = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_ARGB);
        MouseAdapter listener = new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                handleMousePressed(e);
            }

            @Override
            public void mouseDragged(MouseEvent e) {
                handleMouseDragged(e);
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                handleMouseReleased(e);
            }
        };
        content=new JLabel(new ImageIcon(render(iterCounts, bufferedImage, zoomBox, true)));
        content.addMouseListener(listener);
        content.addMouseMotionListener(listener);

        /*OutputStream os = new BufferedOutputStream(new FileOutputStream(fileName));
        try {
            ImageIO.write(bufferedImage, "PNG", os);
        } finally {
            os.close();
        }*/


        frame = new JFrame("Mandelbrot Viewer");
        frame.getContentPane().add(content);
        frame.pack();
        frame.setSize(new Dimension(WIDTH, HEIGHT));
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    public static BufferedImage render(int[][] iterCounts, BufferedImage bufferedImage, Rectangle zoomBox, boolean updated){
        bufferedImage = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_ARGB);
        Graphics g = bufferedImage.getGraphics();
        Graphics2D g2=(Graphics2D) g;
        if(updated){
            for(int i=0; i<WIDTH; i++){
                for(int j=0; j<HEIGHT; j++){
                    if(iterCounts[i][j]<maxIters){
                        String hexCode= String.format("#%06x", (0xFFFFFF & (32*iterCounts[i][j])));
                        g.setColor(Color.decode(hexCode));
                    }
                    else{
                        g.setColor(Color.CYAN);
                    }
                    g.drawLine(i, j, i, j);
                }
            }
        }
        else{
            if(zoomBox!=null){
                g2.setStroke(new BasicStroke(7));
                g2.draw(zoomBox);
            }
        }

        return bufferedImage;
    }

    public static int[][] recalculate(double x1, double y1, double x2, double y2, int[][] iterCounts){
        MandelbrotTask[] tasks=new MandelbrotTask[4];
        tasks[0]=new MandelbrotTask(maxIters, x1, y1, x2, y2, 0, WIDTH, 0, HEIGHT/4, iterCounts);
        tasks[1]=new MandelbrotTask(maxIters, x1, y1, x2, y2, 0, WIDTH, HEIGHT/4, 2*(HEIGHT/4), iterCounts);
        tasks[2]=new MandelbrotTask(maxIters, x1, y1, x2, y2, 0, WIDTH, 2*(HEIGHT/4), 3*(HEIGHT/4), iterCounts);
        tasks[3]=new MandelbrotTask(maxIters, x1, y1, x2, y2, 0, WIDTH, 3*(HEIGHT/4), 4*(HEIGHT/4), iterCounts);
        //parallelize computation
        Thread[] threads=new Thread[4];
        for(int i=0; i<4; i++){
            threads[i]=new Thread(tasks[i]);
        }

        System.out.println("Working...");
        //start timer, start computation
        long start=System.currentTimeMillis();
        for(int i=0; i<4; i++){
            threads[i].start();
        }

        for(int i=0; i<4; i++){
            try {
                threads[i].join();
            } catch (InterruptedException e) {
                System.err.println("A thread was interrupted.");
            }
        }
        //end timer
        long end=System.currentTimeMillis();
        long elapsed=end-start;
        System.out.println("Done.");
        System.out.println("Took " + elapsed + " ms.");

        return iterCounts;
    }

    protected static void handleMousePressed(MouseEvent e) {
        initialClick=e.getPoint();
    }

    protected static void handleMouseDragged(MouseEvent e) {
        if(e.getX()>e.getY()){
            zoomBox=new Rectangle((int)initialClick.getX(), (int)initialClick.getY(), (int)(e.getX()-initialClick.getX()), (int)(e.getY()-initialClick.getX()));
        }
        else if(e.getY()>e.getX()){
            zoomBox=new Rectangle((int)initialClick.getX(), (int)initialClick.getY(), (int)(e.getX()-initialClick.getY()), (int)(e.getY()-initialClick.getY()));
        }
        else{
            zoomBox=new Rectangle((int)initialClick.getX(), (int)initialClick.getY(), (int)(e.getX()-initialClick.getX()), (int)(e.getY()-initialClick.getY()));
        }
        content=new JLabel(new ImageIcon(render(iterCounts, bufferedImage, zoomBox, false)));
        content.repaint();
    }

    protected static void handleMouseReleased(MouseEvent e) {
        recalculate(initialClick.getX(), initialClick.getY(), e.getX(), e.getY(), iterCounts);
        SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run() {
                zoomBox=null;
                content=new JLabel(new ImageIcon(render(iterCounts, bufferedImage, zoomBox, false)));
                content.repaint();
            }
        });
    }
}