Nearest neighbor 3-component image resizing function

nearest.c

static uint8_t* resize_nearest(
  uint8_t* source_data,
  uint32_t source_width,
  uint32_t source_height,
  uint32_t resized_width,
  uint32_t resized_height
)
{
  uint32_t x, y, di, si;
  double px, py;
  const double x_ratio = source_width  / (double)resized_width;
  const double y_ratio = source_height / (double)resized_height;
  uint8_t* destination = malloc(resized_width * resized_height * 3);

  for (y = 0; y < resized_height; ++y) {
    for (x = 0; x < resized_width; ++x) {
      px = floor(x * x_ratio);
      py = floor(y * y_ratio);
      di = (y * resized_width) + x;
      si = (uint32_t)((py * source_width) + px);
      memcpy(destination + (3 * di), source_data + (3 * si), 3);
    }
  }

  return destination;
}