mt4 scale question

 

By default mt4 is not to scale . I'm trying to make a simple code . After a candlestick that is 10cm long I would like the expert advisor to place a trade for me  . The problem is depending on the scale at the time a 10cm long candle could either be 10 pips or 5 pips or 3 pips etc , it varies . 

So how could I code a 10cm long candle ?