In Java doc for IChart is not add() method.

I’d like to create (from strategy) in chart indicator window, but without indicator. I’d like to draw in this window from strategy. Draw some objects (small squares) creating points matrix(as a compressed information). Could you advise me?

Thanks

Consider creating an indicator which has an invisible output i.e. OutputParameterInfo.setShowValueOnChart(false) and which implements the IMinMax interface, to allow you to have some constant Y-axis i.e. price-axis value range, say 0 to 100:

    @Override
    public double[] getMinMax(int outputIdx, Object values2, int firstVisibleValueIndex, int lastVisibleValueIndex) {
            return new double[] {0, 100}; 
    }

Then plot the indicator on the chart from the strategy and afterwards plot the chart objects on the panel. Of course alternatively you can also draw chart objects right away from the indicator, see:
https://www.dukascopy.com/wiki/#Indicator_draws_chart_objects
or for more advanced case see HeikinAshiIndicator.java in platform sources:
https://www.dukascopy.com/wiki/#Platform_indicator_source_files

Thanks very much for fast answer. Have a nice weekend.