package graphtest;
import javax.swing.*;
import java.awt.*;
import java.awt.image.MemoryImageSource;
import static java.lang.Math.max;
public class Panel extends JPanel
{ private Image img;
  @Override // переозначення методу малювання
  public void paintComponent (Graphics g) 
  { super.paintComponent(g); 
    g.setColor(Color.yellow);
    Graphics2D g2 = (Graphics2D) g;
    int w = getSize().width,
        h = getSize().height;
    int [] pix = new int [w*h];
    for (int x = 0; x < w; x++)
    { for (int y = 0; y < h; y++)
      { int red   = max(0,255 -(x + y)/2);
        int blue  = max(0,255 -(x + (h-y-1))/2);
        int green = max(0,255 -((w-x-1) + y)/2);
        pix [w*y+x] = (255 << 24) | (red << 16) | (green << 8) | (blue << 0);
      }
    }
    if (img == null) 
    img = createImage (new MemoryImageSource (w, h, pix, 0, w));
    g2.drawImage (img, 0, 0, this);
  }
}