import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.File;
import java.io.IOException;

/** Let's make a French flag:  blue, white, red.
 *  Creating an image in Java is pretty simple.  But don't memorize the
 *    syntax.  There are 3 steps:  create an image object, write pixel
 *    values, and finally put the image object into a file.
 *  The interesting part is writing the pixel values.  We use the RGB
 *    (Red, Green, Blue) color system.  We need to tell each pixel how much
 *    of each primary color we want, in the range from 0-255.
 *    When we call the setRBG() function, we need to pass it this number:
 *        65536*R + 256*G + B.    
 */
public class Flag
{
  public static void main(String [] args)
  {
    // First, create an image object.
    // The parameters to the constructor are: 
    //   width, height, and image type (we use 1)
    BufferedImage image = new BufferedImage (300,200,1);

    // Second, write pixel values into the image.
    // The French flag has 3 equal portions of blue, white, red.
    //   In all 3 cases, we want the height(y) to range 0-199.
    //   The blue portion is where x is 0-99, etc.
    // Note:  in Cartesian coordinates, x is horizontal, y is vertical.

    int blueNumber  =   0*65536 +   0*256 + 255;
    int whiteNumber = 255*65536 + 255*256 + 255;
    int redNumber   = 255*65536 +   0*256 +   0;

    for (int x = 0; x < 300; ++x)
      for (int y = 0; y < 200; ++y)
      {
        if (x < 100)
          image.setRGB(x, y, blueNumber);
        else if (x < 200)
          image.setRGB(x, y, whiteNumber);
        else
          image.setRGB(x, y, redNumber);
      }

    // Third, write the image to a file.  
    // May automatically throw "IOException"
    try
    {
      ImageIO.write(image, "png", new File ("france.png"));
    }
    catch (IOException e)
    {
      System.out.printf("Encountered problem trying to write to file\n");
    }
  }
}