以编程方式创建简单图像并显示它

class ImageCreationExample {
  
    static Image createSampleImage() {
        // instantiate a new BufferedImage (subclass of Image) instance 
        BufferedImage img = new BufferedImage(640, 480, BufferedImage.TYPE_INT_ARGB);
        
        //draw something on the image
        paintOnImage(img);
        
        return img;
    }

    static void paintOnImage(BufferedImage img) {
        // get a drawable Graphics2D (subclass of Graphics) object 
        Graphics2D g2d = (Graphics2D) img.getGraphics();
        
        // some sample drawing
        g2d.setColor(Color.BLACK);
        g2d.fillRect(0, 0, 640, 480);
        g2d.setColor(Color.WHITE);
        g2d.drawLine(0, 0, 640, 480);
        g2d.drawLine(0, 480, 640, 0);
        g2d.setColor(Color.YELLOW);
        g2d.drawOval(200, 100, 240, 280);
        g2d.setColor(Color.RED);
        g2d.drawRect(150, 70, 340, 340);
        
        // drawing on images can be very memory-consuming
        // so it's better to free resources early
        // it's not necessary, though
        g2d.dispose();
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Image img = createSampleImage();
        ImageIcon icon = new ImageIcon(img);
        frame.add(new JLabel(icon));
        frame.pack();
        frame.setVisible(true);
    }
}