View source for Implementing the flood fill algorithm

===Java=== 
This is next algorithm adapted by Claudio Santana and Damian Johnson for Java:

<pre class="java">
  /**
   * Fills the selected pixel and all surrounding pixels of the same color with the fill color.
   * @param img image on which operation is applied
   * @param fillColor color to be filled in
   * @param loc location at which to start fill
   * @throws IllegalArgumentException if loc is out of bounds of the image
   */
  public static void floodFill(BufferedImage img, Color fillColor, Point loc) {
    if (loc.x < 0 || loc.x >= img.getWidth() || loc.y < 0 || loc.y >= img.getHeight()) throw new IllegalArgumentException();
    
    WritableRaster raster = img.getRaster();
    int[] fill =
        new int[] {fillColor.getRed(), fillColor.getGreen(), fillColor.getBlue(),
            fillColor.getAlpha()};
    int[] old = raster.getPixel(loc.x, loc.y, new int[4]);
    
    // Checks trivial case where loc is of the fill color
    if (isEqualRgba(fill, old)) return;
    
    floodLoop(raster, loc.x, loc.y, fill, old);
  }
  
  // Recursively fills surrounding pixels of the old color
  private static void floodLoop(WritableRaster raster, int x, int y, int[] fill, int[] old) {
    Rectangle bounds = raster.getBounds();
    int[] aux = {255, 255, 255, 255};
    
    // finds the left side, filling along the way
    int fillL = x;
    do {
      raster.setPixel(fillL, y, fill);
      fillL--;
    } while (fillL >= 0 && isEqualRgba(raster.getPixel(fillL, y, aux), old));
    fillL++;
    
    // find the right right side, filling along the way
    int fillR = x;
    do {
      raster.setPixel(fillR, y, fill);
      fillR++;
    } while (fillR < bounds.width - 1 && isEqualRgba(raster.getPixel(fillR, y, aux), old));
    fillR--;
    
    // checks if applicable up or down
    for (int i = fillL; i <= fillR; i++) {
      if (y > 0 && isEqualRgba(raster.getPixel(i, y - 1, aux), old)) floodLoop(raster, i, y - 1,
          fill, old);
      if (y < bounds.height - 1 && isEqualRgba(raster.getPixel(i, y + 1, aux), old)) floodLoop(
          raster, i, y + 1, fill, old);
    }
  }
  
  // Returns true if RGBA arrays are equivalent, false otherwise
  // Could use Arrays.equals(int[], int[]), but this is probably a little faster...
  private static boolean isEqualRgba(int[] pix1, int[] pix2) {
    return pix1[0] == pix2[0] && pix1[1] == pix2[1] && pix1[2] == pix2[2] && pix1[3] == pix2[3];
  }
</pre>