Function render_trade_delta 

pub fn render_trade_delta(
    painter: &Painter,
    mapping: &ChartMapping,
    values: &[TradeDeltaValue],
    style: TradeDeltaStyle,
    buy: Color32,
    sell: Color32,
)

Draws exact delta values using the supplied pane’s mapping and colours. values has the same global bar indices as the price chart. The host fits the pane’s scale, including zero, to delta (histogram), delta_low to delta_high (bar candles) or low to high (cumulative candles). A bar whose delta is zero or more is drawn in buy, otherwise in sell.