rem: scale_line_1_1 (guchar * source, guchar * dest, gint width, gint step)
add: scale_line_1_1 (guchar * source, guchar * dest, int width, int step)
context: scale_line_1_1 (guchar * source, guchar * dest, gint width, gint step){    memcpy (dest, source, width);}