public void updatePixels(int x, int y, int c, int d) {
    //if ((x == 0) && (y == 0) && (c == width) && (d == height)) {
    if ((x != 0) || (y != 0) || (c != width) || (d != height)) {
      // Show a warning message, but continue anyway.
      showVariationWarning("updatePixels(x, y, w, h)");
    }