A clear portion of the graphics with the main image

Question

I am making a “game” in which the player must click on the image bouncing around the screen. The trick is that the screen is in the dark, and the mouse cursor is a "flashlight" that "lights up" around it in a small circle.

I have JFramein one class consisting of:

public class GameFrame {

public static void main(String[] args) throws IOException {

    Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
    JFrame jf = new JFrame("Flashlight Game");
    jf.setVisible(true);
    jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jf.setSize(d);
    jf.setLocationRelativeTo(null);
    GamePanel gp = new GamePanel();
    jf.add(gp);
}

}

I have another class that extends JPanel. Here are its fields related to my problems:

private Point mouse; //location set by a MouseMotionListener
private BufferedImage myImage;
private int imageX;
private int imageY;
private int imageSpeedX;
private int imageSpeedY;

My first problem is flashlight. In my method, paintI set the background color of the graphic to the background color of the panel and use the method clearRectto clear the area around the mouse cursor.

public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    super.paint(g2);
    checkBounce();
    move();
    g2.drawImage(myImage, imageX, imageY, null);
    g2.setColor(Color.BLACK);
    g2.fillRect(0, 0, this.getWidth(), this.getHeight());
    g2.setBackground(Color.WHITE);
    g2.clearRect((int) mouse.getX() - 25, (int) mouse.getY() - 25, 50, 50);
    try {
        Thread.sleep(10);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    repaint();
}

. 1.) clearOval, , 2.) , ? , g2.setBackground(Color.WHITE) "" , , JFrame JPanel.

, , int, , - .

Answer 1

, Rectangle , , Ellipse2D, "" " " Ellipse2D Rectangle, , .

• paint, , paintComponent, paint , .
• paintXxx. , . , . - javax.swing.Timer repaint
• Thread.sleep, Threasd.wait - . Swing - . . -, EDT, , ...
• repaint , paintXxx. , , ...

....

• Concurrency Swing

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Spotlight {

    public static void main(String[] args) {
        new Spotlight();
    }

    public Spotlight() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public static final int RADIUS = 80;

        private BufferedImage img;
        private Point mousePoint;

        public TestPane() {
            try {
                img = ImageIO.read(new File("C:\\hold\\thumbnails\\Rampage_Small.png"));
            } catch (IOException ex) {
                Logger.getLogger(Spotlight.class.getName()).log(Level.SEVERE, null, ex);
            }

            addMouseMotionListener(new MouseAdapter() {
                @Override
                public void mouseMoved(MouseEvent e) {
                    mousePoint = e.getPoint();
                    repaint();
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (img != null) {
                Graphics2D g2d = (Graphics2D) g.create();
                g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
                g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
                g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
                g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
                g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
                g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);

                int x = (getWidth() - img.getWidth()) / 2;
                int y = (getHeight() - img.getHeight()) / 2;

                g2d.drawImage(img, x, y, this);

                x = mousePoint == null ? getWidth() / 2 : mousePoint.x;
                y = mousePoint == null ? getHeight() / 2 : mousePoint.y;

                Rectangle rect = new Rectangle(0, 0, getWidth(), getHeight());
                Ellipse2D spot = new Ellipse2D.Float(
                        (float) x - (RADIUS / 2f),
                        (float) y - (RADIUS / 2f),
                        (float) RADIUS,
                        (float) RADIUS);

                Area area = new Area(rect);
                area.subtract(new Area(spot));

                g2d.setColor(Color.BLACK);
                g2d.fill(area);

                g2d.dispose();
            }
        }
    }

}