/**
 * Filter that flips the image horizontally.
 * @author Parag
 * @version February 25, 2003
 * 
 * DO NOT MODIFY THIS CLASS
 */
public class FlipHorizontalFilter implements Filter {
  // no instance variables -- no state of objects
  
  /** this filter takes a pixel image and flips it horizontally */
  public void filter(PixelImage pi) {
    Pixel[][] data = pi.getData();
    
    for (int row = 0; row < pi.getHeight(); row++) {
      for (int col = 0; col < pi.getWidth() / 2; col++) {
        Pixel temp = data[row][col];
        data[row][col] = data[row][pi.getWidth() - col - 1];
        data[row][pi.getWidth() - col - 1] = temp;
      }
    }  
    pi.setData(data);
  }
}